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Faculty of Engineering
Drilling Parameters In Relation To
Penetration Rates, As a Tool to Predict
the Type of Rock
MSc. Thesis
Submitted by
Eng. Wael Rashad Elrawy Abdellah
Department of Mining and Metallurgy
Engineering
Faculty of Engineering – Assiut University
2007
كليـة الهندســة
‘ بمعدالت التوغل معامالت الحفر وعالقتها
نوع الصخر لتوقع كوسيلة
تيررسالة ماجس
مقدمة من
عبدالاله وائل رشاد الراوى المهندس/
التعدين والفلزاتهندسة قسم
جامعة أسيوط –كلية الهندسة
م 7002
Drilling Parameters In Relation To Penetration
Rates, As a Tool to Predict the Type of Rock
By
Wael Rashad Elrawy Abdellah
B.Sc., Mining and Metallurgy Engineering
Assiut University, 2003
A THESIS
Submitted in partial fulfillment of the
requirement for the degree
MASTER OF SCIENCE
Department of Mining and Metallurgy
ASSIUT UNIVERSITY
Assiut, Egypt
2007
Supervision Committee: Arbitration Board:
Prof. Dr. Mostafa M. El Biblawi Prof. Dr. Mahmoud F.El-Karamani
Prof. Dr. Mohamed A. Sayed Prof. Dr. Adel S.Abdel-Khalek
Dr. Mostafa T. Mohamed
Assiut University
Faculty of Engineering
Drilling Parameters in Relation to Penetration Rates, as a
Tool to Predict the Type of Rock
By
Wael Rashad Elrawy Abdellah
A thesis submitted to the Graduate Studies in partial fulfillment of the requirements for the
degree of
Master of Science
Department of Mining and Metallurgical Engineering
Assiut University
Assiut, Egypt
July 2007
Wael Abdellah 2007
All rights reserved.
i
ARABIC ABSTRACT
وعالقتها بمعدالت التوغل, كوسيلة لتوقع نوع الصخرمعامالت الحفر
فى هذا البحث تم استخدام ماكينة حفر دوار ذات بنطة مطعمة بالماس لعمل عينات أسطوانية فى ثالثة أنواع من
:فةالصخور والتى تمثل الصخور الرسوبية والمتحولة والنارية. وكانت على الترتيب الحجر الجيرى من خمسة مواقع مختل
المنيا , والرخام -ثالثة مواقع فى أسيوط هي الزرابى , منقباد , أسمنت أسيوط , العيسوية بسوهاج , وبنى خالد بسمالوط
األبيض واألسود من وادى المياه بالصحراء الشرقية , والجرانيت األحمر من أسوان, والجرانيت األسود من على طريق
مرسى علم.–إدفو
من البحث تمت دراسة تأثير كل من الحمل الواقع على البنطة وسرعة الدوران على معدل الحفر فى الجزء األول
والطاقة المستهلكة وعزم اللي أو التدوير وتم اختيار عدة أحمال وكذلك سرعات مختلفة باستخدام نوعين من البنط المطعمة
الذى يعطى أكبر معدل للحفر وأقل قيمة للطاقة بالماس إحداهما مستعملة واألخرى جديدة. واتضح أن الحمل المثالى
كجم لكل من حجر جيرى الزرابى 06كجم لحجر جيرى المنيا , 561كجم للحجر الجيرى "منقباد" , 06المستهلكة كان
056كجم. وكان فى الجرانيت األحمر 06والعيسوية وأسمنت أسيوط. وكان الحمل المثالى فى الرخام األبيض واألسود
5666كجم عند السرعة العالية ) 006لفة/دقيقة(, 066كجم عند السرعة البطيئة ) 086, وفى الجرانيت األسود كجم
لفة/دقيقة(.
وبعد حساب معدالت الحفر والطاقة المستهلكة عند األحمال والسرعات المختلفة تم توقيع العالقات بين الحمل على
لمستلهكة , وعزم اللي أو التدوير وكذلك معدل الحفر مع الطاقة المستهلكة. وتم البنطة وكل من معدل الحفر , الطاقة ا
استنتاج المعادالت الرياضية والتى تمثل هذه العالقات.
وفى الجزء الثانى من البحث أمكن التعرف على أنواع الصخور التى تم حفرها باستخدام معامل جديد هو عبارة عن
على الطاقة المستهلكة عند السرعات واألحمال المختلفة. ثم تم توقيع العالقات بين هذا قسمة مقاومة الصخر للضغط
لفة/دقيقة مع البنطة 5666لفة/دقيقة , 066المعامل الجديد ومعدالت الحفر لكل الصخور موضع الدراسة عند سرعتين هما
األحمال والسرعات العالية والمنخفضة لم يكن الجديدة وأحمال مختلفة. من هذه العالقات اتضح أنه عند استخدام مختلف
هناك فاصل واضح لألنوع المختلفة من الصخور وإنما كان هناك تداخل بينها ،وتم استبعاد األحمال الصغيرة و استخدام
لفة/دقيقة(أمكن التمييز بوضوح بين منطقتين فقط على الرسم واحدة تمثل 066األحمال الكبيرة مع السرعة المنخفضة )
الصخور الرسوبية واألخرى تمثل الصخور المتحولة والنارية معا.و عند استخدام نفس األحمال الكبيرة ولكن مع السرعات
لفة/دقيقة( أمكن التمييز بوضوح بين ثالثة مناطق على الرسم كل منها يختص بنوع بذاته من الصخور 5666العالية )
ة باإلضافة إلى بعض المعلومات عن الصخور من الفتات الناتج أثناء الحفر الثالثة. وعليه فإنه يمكن استخدام هذه الطريق
. للتعرف على أنواع الصخور التى يتم الحفر فيها
ii
English ABSTRACT
Three categories of rocks represent sedimentary, metamorphic and igneous rocks were
cored by a diamond core bit. Five types of limestone, three of them are from Assiut, namely:
Zaraby, Mankabad, and Assiut cement company quarry, and the fourth type of limestone is
from Issawyia, east Sohag, and fifth type is from Beni-Khalid, Samalout- Minia. Two types
of marble namely are: White and Black marble from Wadi-El-Miah, Idfu- Marsa Alam road,
Eastern Desert. Two types of granite namely, pink and Black granite from Aswan. Then the
most important physical and mechanical properties of the tested rocks were determined, such
as density, porosity, compressive strength, tensile strength, Shear strength and coefficient of
internal friction ().
A fixed laboratory-core drilling machine is used at two rotational speeds, 300 and
1000 rpm, at different ranges of weights on bit (WOB). Drilling parameters such as weight on
bit (WOB), rate of penetration (ROP), torque and drilling specific energy (SE) were
continuously monitored during the drilling operations. Two core bits were used in drilling
operations; one of them is new and the other is used. The effects of the drilling parameters on
the performance of the two bits were examined. Relationships between WOB and both ROP
and SE were also plotted.
Specific energy (SE) for drilling in all types of rocks under investigation at different
applied loads and rotary speeds have been determined and plotted against rate of penetration
(ROP) to show the variation in specific energy with the different rocks. A new dimensionless
index Uniaxial Compressive Strength divided by specific energy (UCS/SE) was calculated.
The rates of penetration (ROP) against (UCS/SE) for all tested rocks were plotted. The
interpretation of these relationships indicates that at lower thrust loads and higher rotary
speeds the three groups of rocks are lying into distinct zones. Whereas, at higher thrust loads
and higher rotary speeds; it is possible to obtain only two distinct areas for the three groups of
rocks, one for sedimentary only and the other for metamorphic and igneous together. From
these results together with other information obtained from analysis of drill cuttings it can be
possible to identify the rock category being drilled.
iii
DEDICATION
This work is dedicated to my parents: Rashad Elrawy and Irdina Hamdallah,
With all the warmth of a thankful son;
My wife: Lobna Sayed Mohamed;
My daughters: Mennatallah and Hebatallah;
And my siblings: Hazem, Manal, Mervat, Nashwa and Hala,
With all the joy of a lucky brother
iv
ACKNOWLEDGMENTS
First of all, my gratitude and thanks are for Allah, our creator and the most merciful. It
is the pleasure of the author to record his sincere thanks to Prof. Dr. Mostafa El-Beblawi,
Prof. Dr. Mohamed Sayed, and Dr. Mostafa Tantawy, Mining and Metallurgical
Engineering Department, Faculty of Engineering, University of Assiut, Egypt. I am truly
grateful for their support, generous portion of time, technical expertise, encouragement and
constructive criticism to transform what has been done. I wish to express my thanks to all
technicians and workers of the Department of Mining and Metallurgical Engineering at Assiut
University for their extensive help and cooperation. Finally, the author would like to thank
everyone who helped in one way or another in making this work come into light.
Eng. Wael Rashad Elrawy Abdellah
July, 2007
v
CONTRIBUTIONS OF AUTHORS
This thesis is prepared in accordance with the guidelines of the Graduate Studies office of
Assiut University. The following two manuscripts are published from this thesis:
1. Abdellah, W., Mohamed, M. T., Sayed M. ., and EL-Beblwi, M. M., Effect of Rotary
speed and Weight on bit on drilling rate and Specific Energy Using Different rocks,
The 10th
International Mining, Petroleum, and Metallurgical Engineering Conference
(MPM), Assiut University, Fac. of Eng. Min. and Metal. Eng. Dept., March 6-8, 2007.
2. Abdellah, W., Mohamed, M. T., Sayed M. ., and EL-Beblwi, M. M., Some drilling
parameters as a tool to differentiate between sedimentary, metamorphic, and igneous
rock, Journal of Engineering Science (JES), , Fac. of Eng. Assiut, Egypt, Vol.34, June,
2007.
vi
Contents ARABIC ABSTRACT ................................................................................................................ i
English ABSTRACT .................................................................................................................. ii
DEDICATION .......................................................................................................................... iii
ACKNOWLEDGMENTS ......................................................................................................... iv
CONTRIBUTIONS OF AUTHORS .......................................................................................... v
LIST OF TABLES .................................................................................................................... xi
CHAPTER 1 ............................................................................................................................. 1
1 Background ......................................................................................................................... 1
1.1 INTRODUCTION ....................................................................................................... 1
1.2 The specific objectives of this study............................................................................ 4
2 LITERATURE REVIEW ................................................................................................. 5
2.1 General ......................................................................................................................... 5
2.2 Historical Developments ............................................................................................. 6
2.3 Drilling methods ........................................................................................................ 10
2.3.1 Percussion drilling .............................................................................................. 10
2.3.2 Rotary drilling .................................................................................................... 16
2.3.3 Auger drilling ..................................................................................................... 19
2.3.4 Diamond drilling ................................................................................................ 20
2.3.5 Heavy rotary blast hole drilling .......................................................................... 21
2.3.6 Rotary- Percussive drilling ................................................................................. 22
2.4 Major factors influencing penetration rate ................................................................ 24
2.4.1 Weight on bit (WOB) and Rotary speed (RPM) ................................................ 25
2.4.2 Bit type and Condition ....................................................................................... 25
2.4.3 Rock properties .................................................................................................. 26
2.4.4 Fluid properties (Circulation) ............................................................................. 27
2.5 Automatic optimization of drilling techniques .......................................................... 28
vii
2.5.1 Drill productivity evaluation by monitoring ...................................................... 28
2.5.2 Rock characterization by monitoring ................................................................. 28
2.5.3 Measurement While Drilling (MWD) ................................................................ 29
2.5.4 Rotary and Percussive drilling rate prediction models ....................................... 30
2.6 Future perspective of drilling techniques .................................................................. 31
2.6.1 Safety and health ................................................................................................ 31
2.6.2 Productivity ........................................................................................................ 32
CHAPTER 3 ............................................................................................................................. 33
3 STEPS OF THE EXPERIMENTAL WORK AND PROCEDURES ............................... 33
3.1 Rock properties .......................................................................................................... 34
3.2 Drilling operations ..................................................................................................... 35
3.3 Experimental data of drilling tests ............................................................................. 39
CHAPTER 4 ............................................................................................................................. 47
4 RESULTS AND DISCUSSIONS ..................................................................................... 47
4.1 Effect of both weight on bit, rotary speed, and bit condition on rate of penetration . 47
4.2 Effect of both weight on bit, rotary speed and bit conditions on torque ................... 56
4.3 Effect of weight on bit, rotary speed, and bit condition on specific energy .............. 58
4.4 Relationships between rate of penetration (ROP) and specific energy (SE) for all
tested rocks ........................................................................................................................... 68
4.5 Identifying the rock type to be drilled using drilling parameters .............................. 74
4.5.1 I -Variation of specific energy with the rock types ............................................ 75
4.5.2 II- Relation between UCS/SE and ROP ............................................................. 78
CHAPTER 5 ............................................................................................................................. 82
5 CONCLUSIONS AND RECOMMENDATIONS ........................................................... 82
REFERENCES ......................................................................................................................... 85
viii
List of Figures
Figure 1.1: Location of map of the studied rocks ...................................................................... 3
Figure 2.1: different drilling methods [19] ............................................................................... 11
Figure 2.2: Cable tool drilling [30] ......................................................................................... 12
Figure 2.3: Down-the-Hole hammer schematic [31] ............................................................... 15
Figure 2.4: Diagram of Reverse circulation drilling system [42]. ........................................... 19
Figure 2.5: different types of drilling bits [19] ......................................................................... 26
Figure 2.6: schematic representation of the MWD system [59] .............................................. 29
Figure 3.1: Program of the experimental work ........................................................................ 33
Figure 3.2: Diamond core drilling machine ............................................................................. 37
Figure 3.3: Schematic representation of the drilling machine [11]. ......................................... 38
Figure 4.1: Relation between weight on bit (WOB) and rate of penetration (ROP) at 300 and
1000 rpm in Mankabad limestone, Assiut ................................................................................ 47
Figure 4.2: Relation between weight on bit and rate of penetration at 300 and 1000 rpm in
Beni Khalid- Samalout limestone, Minia ................................................................................. 48
Figure 4.3: Relation between weight on bit and rate of penetration at 300 and 1000 rpm in
Assiut limestone ....................................................................................................................... 48
Figure 4.4: Relation between weight on bit and rate of penetration at 300 and 1000 rpm in
Issawyia limestone, East Sohag ............................................................................................... 49
Figure 4.5: Relation between weight on bit and rate of penetration at 300 and 1000 rpm in
Zaraby limestone, Assiut .......................................................................................................... 49
Figure 4.6: Relation between weight on bit and rate of penetration at 300 and 1000 rpm in
Black marble, Wadi El-Miah ................................................................................................... 50
Figure 4.7: Relation between weight on bit and rate of penetration at 300 and 1000 rpm in
white marble, Wadi El-Miah .................................................................................................... 50
Figure 4.8: Relation between weight on bit and rate of penetration at 300 and 1000 rpm in
pink granite, Aswan .................................................................................................................. 51
Figure 4.9: Relation between weight on bit and rate of penetration at 300 and 1000 rpm in
Black granite, Aswan ............................................................................................................... 51
ix
Figure 4.10: Relation between weight on bit and torque at 300 rpm using new bit, For Zaraby
limestone (Assiut), white (Wadi El-Miah Eastern Desert), and pink granite (Aswan) ............ 57
Figure 4.11: Relation between weight on bit and torque at 300 rpm using used bit, For Zaraby
limestone (Assiut), white marble (Wadi El-Miah Eastern Desert), and pink granite (Aswan) 58
Figure 4.12: Relation between weight on bit and specific energy at 300 and 1000 rpm in
Mankabad limestone ................................................................................................................ 60
Figure 4.13: Relation between weight on bit and Specific energy at 300 and 1000 rpm in
Beni-Khalid, Samalout Limestone, Minia ................................................................................ 60
Figure 4.14: Relation between weight on bit and Specific energy at 300 and 1000 rpm in
Assiut cement company quarry Limestone, Assiut .................................................................. 61
Figure 4.15: Relation between weight on bit and Specific energy at 300 and 1000 rpm in
Issawyia Limestone, East Sohag .............................................................................................. 61
Figure 4.16: Relation between weight on bit and Specific energy at 300 and 1000 rpm in
Zaraby Limestone, Assiut ........................................................................................................ 62
Figure 4.17: Relation between weight on bit and Specific energy at 300 and 1000 rpm in
Black Marble, Wadi El-Miah, Eastern Desert .......................................................................... 63
Figure 4.18: Relation between weight on bit and Specific energy at 300 and 1000 rpm in
White Marble, Wadi El-Miah, Eastern Desert ......................................................................... 63
Figure 4.19: Relation between weight on bit and Specific energy at 300 and 1000 rpm in pink
granite, Aswan .......................................................................................................................... 64
Figure 4.20: Relation between weight on bit and Specific energy at 300 and 1000 rpm in
black granite, Aswan ................................................................................................................ 65
Figure 4.21: Relation between rate of penetration and Specific energy at 300 and 1000 rpm in
Mankabad Limestone, Assiut ................................................................................................... 69
Figure 4.22: Relation between rate of penetration and Specific energy at 300 and 1000 rpm in
Beni-Khalid, Samalout Limestone, Minia ................................................................................ 69
Figure 4.23: Relation between rate of penetration and Specific energy at 300 and 1000 rpm in
Assiut cement company quarry Limestone, Assiut .................................................................. 70
Figure 4.24: Relation between rate of penetration and Specific energy at 300 and 1000 rpm in
Issawyia Limestone, East Sohag .............................................................................................. 70
Figure 4.25: Relation between rate of penetration and Specific energy at 300 and 1000 rpm in
Zaraby Limestone, Assiut ........................................................................................................ 71
x
Figure 4.26: Relation between rate of penetration and Specific energy at 300 and 1000 rpm in
Black Marble, Wadi-El-Miah, Eastern Desert ......................................................................... 71
Figure 4.27: Relation between rate of penetration and Specific energy at 300 and 1000 rpm in
White Marble, Wadi-El-Miah, Eastern Desert ......................................................................... 72
Figure 4.28: Relation between rate of penetration and Specific energy at 300 and 1000 rpm in
Pink Granite, Aswan ................................................................................................................ 72
Figure 4.29: Relation between rate of penetration and Specific energy at 300 and 1000 rpm in
Black Granite, Aswan .............................................................................................................. 73
Figure 4.30: Relationship between average rate of penetration and specific energy for all
rocks at different loads and drilling speed of 1000 rpm ........................................................... 77
Figure 4.31: Relationship between average rate of penetration and specific energy for all
rocks at different loads and drilling speed of 300 rpm ............................................................. 77
Figure 4.32: Relationship between UCS/SE and Rate of penetration for all rocks at different
loads and rotary speed of 1000 rpm, new bit ........................................................................... 78
Figure 4.33: Relationship between UCS/SE and Rate of penetration for all rocks at different
loads and rotary speed of 300 rpm, new bit ............................................................................. 79
Figure 4.34: Relationship between UCS/SE and rate of penetration for all rocks at rotary
drilling of 300 rpm and loads of 45, 60, 75, 90, 120, 150, 180, 210, 300, 390 and 480 kg, new
bit .............................................................................................................................................. 81
Figure 4.35: Relationship between UCS/SE and rate of penetration for all rocks at rotary
drilling of 1000 rpm and loads of 45, 60, 75, 90, 120, 150, 180, 210, 300, 390 and 480 kg,
new bit ...................................................................................................................................... 81
xi
LIST OF TABLES
Table 2.1: Drilling methods for the various ground conditions [48]. ..................................... 23
Table 3.1: Physical and mechanical properties of the tested rocks .......................................... 35
Table 3.2: Data of the drilling parameters in Mankabad limestone, Assiut ............................. 39
Table 3.3: Data of the drilling parameters in Beni-Khalid- Samalout limestone, Minia ......... 39
Table 3.4: Data of the drilling parameters in Assiut cement company quarry limestone, Assiut
.................................................................................................................................................. 40
Table 3.5: Data of the drilling parameters in Issawyia limestone, east Sohag ......................... 40
Table 3.6: Data of the drilling parameters in Zaraby limestone, Assiut .................................. 41
Table 3.7: Data of the drilling parameters in Black marble, Wadi El-Miah, Eastern Desert ... 41
Table 3.8: Data of the drilling parameters in White marble, Wadi El-Miah, Eastern Desert .. 42
Table 3.9: Data of the drilling parameters in Pink granite, Aswan .......................................... 42
Table 3.10: Data of the drilling parameters in Black granite, Aswan ...................................... 43
Table 3.11: Specific energy and UCS/SE for limestone at 300, and 1000 rpm and different
loads, new bit ............................................................................................................................ 44
Table 3.12: Specific energy and UCS/SE for Marbles at 300, and 1000 rpm and different
loads, new bit ............................................................................................................................ 45
Table 3.13: Specific energy and UCS/SE for Granites at 300, and 1000 rpm and different
loads, new bit ............................................................................................................................ 45
Table 3.14: Average values of rate of penetration and specific energy at rotary speed 1000
rpm at different loads (WOB) ................................................................................................. 46
Table 3.15: Average values of rate of penetration and specific energy at rotary speed 300 .... 46
Table 4.1: Correlation equations of the relationship between rate of penetration and
the weight on bit for all tested rocks at 300 rpm ...................................................................... 52
Table 4.2: Correlation equations of the relationship between rate of penetration and the weight
on bit for all tested rocks at 1000 rpm ...................................................................................... 53
Table 4.3: Correlation equations of the relationship between Torque (T) and weight on bit
(WOB) at 300 rpm .................................................................................................................... 58
Table 4.4: Correlation equations of the relationships between (SE) and (WOB) for all tested
rocks at 300 rpm ....................................................................................................................... 66
xii
Table 4.5: Correlation equations of the relationships between (SE) and (WOB) for all tested
rocks at 1000 rpm ..................................................................................................................... 66
Table 4.6: Best drilling conditions for all tested rocks ............................................................ 67
Table 4.7: Predicted values of drilling rate (ROP, cm/min.) at the best weight on bit (WOB) as
an example for tested rocks ...................................................................................................... 67
Table 4.8: Predicted values of Specific energy (SE, Mpa) at the best weight on bit (WOB) as
an example for tested rocks ...................................................................................................... 68
Table 4.9: Correlation equations of the relationship between (SE) and (ROP) for tested rocks
at 300 rpm ................................................................................................................................. 73
Table 4.10: Correlation equations of the relationship between (SE) and (ROP) for tested
rocks at 1000 rpm ..................................................................................................................... 74
Table 5.1: The range of drilling parameters values related to the three types of rocks ........... 84
1
CHAPTER 1
1 Background
1.1 INTRODUCTION
Drilling is the essential operating step in open pit mines and quarries. It goes
hand-in-hand with the blasting operations to ensure adequately broken material for the
excavation equipment employed. In mining, all the unit operations are interrelated.
However, drilling and blasting are of utmost importance. Optimization of the other
procedures, such as, loading, hauling and crushing operations, depends upon the
desired fragmentation. The economics of these interrelated procedures are strongly
dependent on the drilling and blasting operations, which in turn are directly
responsible for providing the desired rock fragmentation. Therefore, it is critical to
analyze the economics of the drilling and blasting design. The drilling effectiveness is
highly dependent on the quality of drill evaluation [1, 2].
Drilling a hole in the ground with a machine is one of the most common, necessary
and important operations in geotechnical engineering and in the construction and
mining industries. It has long been accepted that, besides its primary purpose, drilling
itself can also be considered as a measurement and in situ technique for ground
characterization [3].
The importance of drilling in mining Engineering as it is an essential and
integral process of mineral exploration to present a clear picture of extent of any ore
body, its mineral content, and the stratigraphy or to confirm any geological or indirect
geological interpretations of what is laying below the earth’s surface. The type of
strata and structure to be drilled has a significant influence on the drilling performance
of a bit. Resistance to penetration, resistance to the shearing action of the bit in
2
rotation and the degree of abrasiveness are the properties that would be expected to
have the greatest influence. The prediction of the penetration rate for the cost estimate
becomes a common problem in mining engineering. However, it is important to note
that the prediction of physical and mechanical properties of the rock formations from
drilling rates may help the mining engineer to control the changing characteristics of
the formations. After a hole is drilled, geophysical measuring instruments are
lowered on steel lines into the mud-and water-filled hole. Characteristics of the rock
such as its conductivity of electricity, other electrical properties, its radioactivity
(using gamma ray log), and porosity (holes in the rock) can all be measured. [4-6].
Cost of drilling is directly related to the performance of drill bits, the drilling
cost is controlled to a large extent by the drilling rate which is heavily influenced by
the wear condition of the bit. Wear may be defined as the removal of material from
solid surfaces as a result of relative sliding motion at the contact surface. Life of drill
bits and bit replacement cost as well as bit maintenance cost often cannot be perfectly
predicted because the factors influencing them are not easy to determine [7, 8].
Geology and rock drilling are more important to the civil Engineer at all stages
in a project; at the planning stage it controls the choice of site and determines the form
of structural work; for example, suitable drills to be chosen and tactical problems to be
solved. The most important in the context of rock drilling and estimating are
concerned with rock structures, map reading and water flow. Bore holes are drilled in
civil Engineering for industrial construction, making surveys of high-way layouts, for
investigation of the soil at the site of construction of dams, bridges, industrial plants
and houses. In addition to this, a good many bore holes and wells are put down to
provide for water supply of industrial and civil installations [[9, 10].
In this present work diamond core bit was used to study some drilling parameters
and their effect on drilling rate as a tool to predict the rock type to be drilled,
experimental work was carried out in the Department of Mining and Metallurgical
Engineering, Faculty of Engineering, Assiut University. Three categories of rocks
were used in this study (sedimentary, metamorphic, and igneous): Sedimentary rocks
3
were represented by five types of limestone namely: from the quarry of Assiut Cement
Company, northwest of Assiut, Samalout Formations from the quarry of Beni khalid,
east of Samalout in Minia, Issawyia limestone, east of Sohag, Mankabad limestone,
north of Assiut and Zaraby limestone, southwest of Assiut. Metamorphic rocks were
represented by two types of marbles namely: black and white marble, collected from
Wadi Al-Miah, Idfu - Marsa Alam road, from Gabal El- Rokham and El- Sowikat
respectively. Igneous rocks were represented by two types of granites namely: black
granite from Aswan and pink granite from Wadi Allaqi, Aswan quarry respectively.
The locations of these collected rock samples are shown in the map Figure 1.1.
Figure 1.1: Location of map of the studied rocks
4
1.2 The specific objectives of this study
1. To study the effect of the drilling parameters such as weight on bit (WOB), bit
type and its condition (new and used), and rotary speed on both rate of
penetration (ROP) and specific energy (SE) consumption of the diamond core
drill.
2. To obtain the optimum weight on bit (WOB) and rotary speed that give high
values of rate of penetration (ROP) and low values of specific energy (SE) in
three categories of studied rocks under test conditions.
3. Using some drilling parameters as a tool to predict the different Categories of
rocks.
5
CHAPTER 2
2 LITERATURE REVIEW
2.1 General
Geologists drill holes into the rock massif for several reasons. Probably the
greatest number of wells are drilled for water and these are the ones most people are
familiar with. But, usually very little rock information can be derived from them
because they are either too shallow or barely drilled into bedrock. They are less than
100 feet (30 meters) deep. Many shallower holes are also drilled to look for coal.
Additionally, state and federal geological surveys drill holes to study the rock and to
evaluate the occurrence of coal, gypsum, limestone and metallic minerals. It is
important to determine what kind of rocks are there and how they were formed. The
deepest well in the world is in Russia and is about 35,000 feet (7 miles, 10 kilometers)
deep [6].
The cycle of production in surface or underground mining includes the
following main operations: drilling, blasting, loading and transportation. Because
drilling and blasting are the primary operations in mining, they have a great effect on
the efficiency of carrying out the next operations. Moreover, they contribute about 20
to 40 % of the total cost of all mining operations [11].
Drilling is the culmination of the mineral exploration process where the third
dimension of a prospect, the subsurface geometry, is defined. Drilling provides most
of the information for the final evaluation of a prospect and will ultimately determine
if the prospect is mineable. Geochemical analyses of the drill samples provide the
basis for determining the average grade of the ore deposit. Careful logging of the drill
samples helps delineate the geometry and calculate the volume of ore, and provides
important structural details. The two principle types of drilling are diamond core
6
drilling and reverse circulation drilling (or RVC drilling). One of the most critical
decisions that must be made prior drilling a well is the selection of casing and bit
programs. This has an important bearing upon drilling economics because it dictates
the size of rig the contractor will use and also influences the number of days that will
be required to drill the well [12, 13].
Roy et al. [14, 15] found that, the success in making the cheapest hole must be
followed by evaluating drilling performance, and said that the minimum cost of
drilling any formation depends upon the ability to achieve the optimum advantageous
application between the following factors:
Average bit penetration rate and bit type and size.
Rig cost per day and drilling equipment.
Drilling fluid and rotary speed.
Bit purchase or rental cost.
Average Cost per foot = [(
⁄ ) ( ) ( )
] (2.1)
The drillability of rock decreases with increasing depth of the hole. Deep rock
will be more compacted and, therefore, harder to be drilled than the shallow rock of
the same type [16].
2.2 Historical Developments
No one knows exactly where the first well was dug; it may have been a shallow
depression in the earth, carried out by the primitive man with bare hands. The ancient
Egyptians have been said that they used corundum dust or pebbles in order to bore
holes in porphyry [17].
The Chinese in the year 1700 BC learned how to drill several hundred feet
through very abrasive and strong limestone to reach fresh water supplies. Also
Chinese are often quoted as drilling deep holes in loess, by the repetitive lifting,
7
dropping and rotating of coupled bamboo rods. Beside the Chinese practiced,
percussion drilling as deep as 1200 meters to obtain salt and water [9, 18].
Trevithick (1810-1820) in Britain built a steam–driven rotary rock drilling
machine. In 1818, the development of agriculture of French Government appropriated
many of drilling wells to the beds of artesian water, which were believed to be deeply
beneath the city of Paris. Isaac Singer (1830-1840) in U.S.A., has developed steam
churn drill. From (1850-1860) drills with a power stroke were invented. Burleigh
(1860-1870) in America designed a commercial piston drill. So that compressed air
was used as operating medium for rock drills [9, 18].
Churn drill or Cable –Tool – Drills were first used for drilling oil wells in
1860’s,butwere later replaced by rotary drills, which more efficient at drilling than
the deeper holes that were required in petroleum exploration. In 1862, the use of
diamond tools started when George Leschot, a Swiss engineer developed the first
drilling machine and diamond-tipped bits in France. Toothed roller cutter bit were
used in America. Ingersoll (1870-1880) in America improved diamond rock drill and
invented the tripod, to drill holes over 2200 ft. (670m); Rand (U.S.A.) developed
mining drills; Hall (U.S.A.) produced the Sullivan diamond drill [9, 19].
In (1880-1890) a diamond – drill hole reached 5734 ft. (1750 m); Holman
(G.B.) produced a rock drill. In (1890- 1900) Commercial pneumatic rock drills were
being produced by Cleveland, Chicago pneumatic, Gardner- Denver, Hardy- Pick,
Holman Bros., Ingersoll-Rand and Others. In 1900, Leyner invented the hammer
drill, the hollow drill steel and the shank, which still bears his name. In (1900-1910)
Huges (U.S.A.) perfected the Tricone bit "Roller cone bit" [9, 19].
An interesting well was dug in ancient time in Cairo, Egypt and is still
producing water as 1900. It is well known as “Joseph’s well”. Ingersoll – Rand
introduced two new 600 series crawler drills at MINExpo 2000. Its ECM-660 drill
sinks holes from 3 – 4 ⁄ in. diameter and is equipped with a Montabert HC120
8
hydraulic drifter drill. Hole cleaning has been enhanced with a GHH-Rand air
compressor that delivers 310 cfm at 140 psi and a high vacuum dust collector [17, 20].
A diamond core drill was made by the Sullivan Machinery Company (1900-
1925), which was driven by 20 steam engine. The depth capacity of drill was
between 360 to 763 meters of 72 mm hole diameter, recovering a 51 mm core, the drill
weighted 3580 kg. It was realized that steam engine powered drills were much too
large and heavy. It gives some indications how rapidly the design of the drill was
developed in those days [17, 18].
In 1930, Rotary machines of conventional table type, prior to the early 1930,
had always been related at speed varying, generally, from 30 to 60 r.p.m. With the
introduction of diamond drill type machines for oil well drilling, the increased
efficiency of higher rotating speed was realized speed varying from 200 to 400 r.p.m.
In mid-1930’s rotary machines were redesigned to accommodate the higher speed
rotation being introduced. Bits and drill pipes were improved; drill collar strings were
increased in length, weight and balance. Presently rotary drills in different
combinations are being used for drilling oil/water wells and blast holes [17].
Tungsten carbide was first used in drill bits (Germany) in (1920-1940). In
(1940-1966) Tungsten – Carbide bits perfected; invention and general acceptance of
down – the- hole drills; introduction of turbine drills. Rock drilling techniques have
undergone rapid development. One of the reasons for this, and not the least important,
is the introduction of new drilling tools equipped with tungsten carbide cutting edges.
The high productivity of the modern mining industry and the building of large civil
engineering projects in this period would have been virtually impossible without the
aid of tungsten carbide tipped drilling tools [9, 17, 19].
Diamond hand – held cutters developed by Chinese hundreds of years ago. It
was the ability to pound a single diamond stone into a suitable brass alloy, which
composed a tool holder. With this invention, they had a method to hold the diamond
and manually impact the rock without shattering the brittle diamond. Many workers
9
would excavate man-sized holes several hundred feet down to gain access to fresh
water. Rotary drilling has been used in surface mining for many years. Its principal use
is for primary blast holes drilling. In this use, holes in the range from 4 to 15 in. in
diameter are drilled in over burden and massive ore bodies for large initial blasting
operation, rotary drilling with diamond bits is used for exploration. Tricone bit 50
years ago, up to 98 percent of the drilling was performed with a more robust roller
cone bit. The introduction of the natural diamond bit 40 years ago resulted in up to 2
percent of the petroleum footage being drilled with relatively small diamond cutters
[21, 22].
Since, the introduction of polycrystalline diamond compact (PDC) bits in the
mid-1970’s their application in the mining and oil industries has represented a
significant advancement in drilling technology. Until 1986 core drilling was carried
out using natural diamond surface set core bits operating at a much higher speed of
300 rpm. Early in 1987, Foraky approached Diamond Boart SA, SYNDAX-3 instead
of natural diamond, in the core bit. SYNDAX-3 increased penetration rates and tool
lives by 100% [19, 23]
Polycrystalline diamond compact (PDC) diamond is no longer thermally stable
at 700 C0. Therefore, one limiting factor for the use of PDC drill bits is petroleum
drilling applications with higher cutter temperatures associated with drilling abrasive
and hard formations. Today, 65 percent of the petroleum footage is drilled with a roller
cone bit and 35 percent with a PDC diamond cutter. About 20 percent of the drilling is
carried out by using carbide insert roller cone bits. Roller cone bits are used to do the
bulk of the drilling in geothermal wells, even though their lives are severely shortened
when the formation temperature exceeds 3500 C0 [21, 24].
The drilling industry, in common with other industries is becoming
increasingly competitive. Machine manufactures and operators are continually
exploring ways of reducing costs and enhancing productivity through the application
of automatic control. Formalized procedures for performance optimizing appeared in
10
the early 1950’s and since then many technical advances have contributed to
development of improved techniques, and introducing automated rigs so that, drilling
costs improved. One of the earliest large- scale systems for the automatic optimization
of rotary refining company. Many companies now offer computer- controlled drilling
systems as well as a wide range of rig sizes and drilling techniques [19, 25].
2.3 Drilling methods
The two drilling methods rotary and percussion are still the basis of all
conventional drilling techniques. There are cable tool percussion, rotary percussive,
down the hole hammer, continuous flight type auger, turbo drill, standard rotary
drilling air, mud or reverse circulation and high speed diamond core drilling, etc. The
various methods of drilling are discussed in the following parts [19].
The type of equipment used depends upon the site, geology, hydrology,
equipment available, and monitoring design. Control of cuttings and other potentially
contaminated materials at the drill site may influence drilling method selection.
Depending upon equipment availability and site geology, more than one method may
be combined to complete a particular monitoring well installation [26]. Some of
conventional drilling methods are introduced in the following Fig. 2.1.
2.3.1 Percussion drilling
There are several methods for drilling rocks, but the most universal, and when it
comes to drilling very hard rock the only efficient one, is percussive method, this
drilling technique is based on generating periodic impact forces in order to enhance
dynamic crack creation and propagation in the brittle type of drilled materials. The
percussion drills consist basically of a hammer unit is driven by compressed air. This
hammer unit imparts a series of short, rapid blows to the drill steel or rods and at the
same time rotates them. The drills vary in size from small hand- held rock drills for
drilling charge holes to large truck- mounted rigs capable of drilling large diameter
11
holes to depths of hundreds of meters. Percussion drilling is a rapid and cheap method
but suffers from the great disadvantage of not providing the precise location of the
samples, as in the case of diamond core drilling. However the price of percussion
drilling is about one third to one half of that for diamond drilling. Percussion drilling
is the technique that is most often used in evaluating deposits and for the drilling of
“blastholes”inminingbusiness[19,27,28, 29].
Figure 2.1: different drilling methods [19]
Percussive Rotary
Churn
DTH
Top
Hammer
With bottom
engine
Non-Core
Diamond Rotary
Percussive
Auger
Reverse
Core
Wire
Line
Conventional
Or
Standard
Double – tube
core barrel
Triple- tube core
barrel
Single – tube core
barrel
Drilling Methods
Conventional
Or
Standard
12
2.3.1.1 Churn or Cable- Tool- Drilling Method
Cable-tool (cable percussion) drilling is the oldest, simplest, and most reliable
technology available of water well drilling. This drilling technique is a portable
equipment, usually mounted on four wheels and driven by steam, diesel, electric, or
gasoline -powered engines or motors and involves chipping and cutting earth materials
by lifting and dropping a heavy, solid chisel- shaped bit, suspended on a wire rope
(steel cable), that is lifted and dropped to break up and remove cuttings from the
bottom of the hole. Steel casing is often used to keep the hole open during drilling in
unstable materials. Casing also is used to isolate potentially contaminated strata.
Figure (2.2) shows the cable tool drilling machine [26, 30, 31].
Figure 2.2: Cable tool drilling [30]
It utilizes the principle of free falling weight to deliver blows against the
bottom of the hole by the movement of the spudding beam. This process of lifting and
dropping (as many as 60 times a minute) of percussion drill develops the mechanical
energy that breaks up the underground formation and bores the holes.
A tight line accompanies drilling in this system so that the bit strikes the bottom
of the hole when stretched. Because of the elasticity of the cable, stretching causes it to
13
unwind and recover when tension is released. The hole cleaning is performed by
retracting the drilling tools and running a bailer to the bottom of the hole. Tools for
drilling and bailing are carried on separate lines or cables spooled on independent
hoisting drums. Cable tools plants are limited to vertical holes only as penetration
depends upon gravity only. Today churn drills are mainly used for water well drilling
and they may be useful in mineral exploration. Churn drills can be useful in
exploration work for sampling soft formations up to depths of 100 – 150 ms. Costs are
comparable to and may be less than percussion drilling. The main disadvantage is that
it is very slow, but if time is not important and if only vertical holes are required,
churn drilling is worth considering [19]. The efficiency of churn drilling was studied
with consideration of wave energy radiation into the rock. In this process, a hammer
with cutters on its front subjects the rock to direct impact [28].
Cable tool has many advantages such as [26, 29, 32]:
Allows for easy and accurate water and soil sampling; easy detection of water
levels during drilling; can detect very thin permeable zones.
Driven casing seals off formation, minimizes threat of cross contamination in
pollution investigation.
Usually successful in drilling through boulders.
Unrestricted as to hole depth, diameter, and geologic and hydrologic conditions.
Produces minimal volumes of cuttings which are easily contained; minimal or
no well development necessary.
Little or no outside drilling fluids necessary.
It is possible to drill in formations where lost circulation is a problem.
Cable tool has little disadvantages such as [26]:
Extremely slow rate of drilling.
Normally necessary to install one or more strings of steel-drilling casing.
14
2.3.1.2 Down -The- Hole hammer (DTH)
Down the hole drilling (DTH) is a rotary percussive drilling technique that is
used in medium to hard formations [31]. In this drilling technique, the motor is inside
"down" the hole, and this advantage makes waves not have to be transferred over
increasing distance as the hole depth increases [33]. The down -the-hole (DTH)
hammer drill has been used widely in mineral deposit exploration, the mining industry,
hydrological drilling and engineering construction, because it has the characteristics of
high efficiency, good drilling quality and low cost. At present, cemented tungsten
carbide is adopted as the cutter of button bits used in the down -the-hole (DTH)
hammer drill, but lower abrasion resistance and short service life of cemented tungsten
carbide seriously affected the drilling efficiency of down -the-hole (DTH) hammer
drilling in an extra hard formations [34]. The hammer unit is lowered into the hole
attached to the lower end of drill rods to operate a non-coring, tungsten carbide tipped,
drill bit sometimes known as a “button bit”. Holes with a diameter of up to 20
centimeters are possible, with penetration depths of up to about 200 meters, but depths
of around 100 - 150 meters are more common [27].
The rods generally vary in diameter from 85 to 115 mm, and bits from 100 to
200 mm. The rigs vary in weight from 1.5 to 3.0 tones and entire truck mounted units
complete with compressor and ancillary equipment may weigh 5 tons or more. Depth
capabilities of up to 250 m are possible with some types, though most rigs are only
capable of reaching depth in the range 100 - 125 m [10, 19]. Figure (2.3) shows down
– hole hammer schematic [31].
Flushing of the drill cuttings from the hole to the surface is carried out using
stream of compressed air; therefore a constant and reliable source is required during
operation. This is usually supplied by a high output air compressing system, which
varies in size depending on the scale and portability of the drilling. Sometimes special
foaming agents are available and used to assist in flushing out holes in wet ground.
Down-the- hole hammer drills are mainly used for shot hole and water well drilling
and are not commonly used in mineral exploration [19, 27].
15
Drilling with water driven down-the- hole (DTH) hammers is a recently
developed method for competitive production of boreholes [35].
Figure 2.3: Down-the-Hole hammer schematic [31]
2.3.1.3 Top hammer drill
In this type of drill, both the percussive and rod rotation are provided by a
hammer unit powered by compressed air at the top of drill system, and the energy to
the non-coring drill bit is transferred through the drill rods. This type of system is
usually smaller than down –the- hole drills and they are used for holes up to 10
centimeter (cm) in diameter and drill up to depths of 100 meters (m). Usually this type
of drill rig is only employed to depths of no more than 20 meters. Most units only use
light portable air [28].
16
The hammer unit is track mounted on the rig and is moved up or down by a
chain feed, and the holes that are drilled by top hammer drills are smaller in
diameters than those drilled by down-the hole drills, with rods varying in diameter
from 38 to 45 mm and bits from 64 to 102 mm. For using in mineral exploration the
drills are usually mounted on trailers, truck or large tractors, and for using in quarries
open pits drills are sometimes mounted on truck- laying vehicles and are then referred
to as crawler drills. The latest machines are all hydraulically controlled and are easily
operated by one man and a helper. Most percussion drills only use air for flushing the
hole, but some machines use equipment designed for water circulation and flushing.
For mineral exploration drills with water flushing facilities are far superior. The
samples produced by percussion drills vary from fine dust to small chips depending
upon the nature of rock being drilled. Coarse, friable grit, for example, may result in
samples with high proportion of coarse fragments, whereas samples from massive
limestone may be largely dust. Whatever rock being drilled, however, it is usually
possible to recognize rock types from the sample fragments as there are always fair
proportions ranging in size from 1.0 to 2.0 mm. Although, this system is generally
limited to drilling small diameter wells through rapid clay and sand formations, but it
gives accurate samples. For any percussive drilling process, a hammer with cutters on
its front subjects the rock to direct impact [10, 19, 28, 36].
2.3.2 Rotary drilling
In the rotary drilling method, action is accomplished by rotating a drill pipe by
means of a power driven rotary table or hydraulic powered top head drive, with a bit
attached to the bottom of the pipe. The bit cuts and breaks up the materials as it
penetrates the formation. Drilling fluid for mud is pumped through the rotating drill
pipe and through holes in the bit. This fluid swirls in the bottom of the hole picking up
material broken by the bit, then flows upward in the space outside the drill pipe,
carrying the cuttings to the ground surface and clearing the hole. Rotary drilling with
mud is the most widely used method for water well construction. A rotary drill rig has
three functions: rotating the drill string, hoisting the drill string and circulating the
17
drilling fluid. A bit is rotated against the formation while mud is pumped down the
drill pipe, through ports in the bit, and back to the ground surface through the annulus
between the drill pipe and the borehole wall [37, 38]. Rotary drilling can be subdivided
into rotary cutting and rotary crushing, rotary cutting creates the hole by shear forces,
breaking the rock’s tensile strength, while, rotary crushing breaks the rock by high
point load, accomplished by a toothed drill bit, which is pushed downwards with high
force [39].
Rotary systems work well in soft formations, the drilling rate decreasing as
rock hardness increases. Rotary drilling system relies upon high rotational speeds and
thrust without percussion to achieve the desired effect and outputs. Heavy drill collars
are sometimes needed to add extra thrust to the bit. Rotary machines are usually large
self-contained hydraulically powered units with sufficient weight to provide the thrust
on the drill bit to drill the hole. The harder the rock the greater the thrust required, the
heavier the machine, the greater initial capital outlay, the higher the operating costs.
The same factors apply when hole diameters are increased. Excessive thrusts can lead
to deviation of borehole particularly when drilling at angles in bedded formations [10].
The rotary drilling method has the following advantages [26]:
1. Quite fast efficient means of drilling; several hundred feet of bore-hole
advancement per day is possible.
2. Capable of drilling to full range of depths and diameters necessary for
monitoring- well installation.
3. Direct-mud rotary effective in all hydrologic conditions.
4. Rotary drilling easily supports the telescoping of casing to isolate drilled
intervals and prevent cross contamination of strata encountered during
drilling.
5. Geophysical logs such as self-potential and resistivity (which must be run
in an uncased bore hole) may be run before well installation, and
6. Efficient rigs offer several hundred feet of hole per day.
18
The rotary disadvantages are:
1. Potential cross contamination of strata exposed to the fluid circulation
during drilling, so that drill fluids may invade permeable zones.
2. It has some inherent defects for monitoring- well installation.
2.3.2.1 Reverse circulation drilling
The reverse circulation rotary drilling operates by the same general principles
as direct mud- rotary except that drilling fluid is pumped down the drill rods and
returns with the drill cuttings up through the annulus. The reverse circulating rotary
method is best suited to drilling in relatively stable to consolidated formations.
Reverse circulation rotary technique is very fast and efficient means of drilling. Rigs
are equipped and staffed so that they can drill several hundred feet of hole per day.
This drilling method can reach several thousand feet in depth and create hole
diameters up to approximately 17 inches [26]. This reverse type of drilling is a suction
dredging method in which cuttings are removed by a suction pipe. The rig includes a
large – capacity centrifugal pump, a drill pipe, and a bit, which resembles a dredge
[40].
There are two types of reverse circulating drilling available today. Both of
these methods use the exact same dual drill pipe. The only difference is the hammer
that attaches to the pipe. The two types of reverse circulating drilling are: Center
sample and the conventional reverse circulating drilling. The center sample reverse
circulating drilling is the newer of the two methods, and uses special center sample
hammer. The advantage of this method is the sample goes immediately into the drill
pipe without having to travel up the side of the conventional hammer. Figure (2.4)
shows the reverse circulating drilling system [41, 42].
19
Figure 2.4: Diagram of Reverse circulation drilling system [42].
2.3.3 Auger drilling
It is another drilling method employed in loose formations. Auger drills are
widely used for making vertical and inclined (angling) drill holes mainly in collieries
(coal, clay, stone, soft limestone), and when working non- strong kind of rock (marl,
soft limestone) used in construction. The auger drilling practices are characterized by
the feed force, rotation speed of the drilling tool and efficiency with which the cuttings
are moved from the drill hole. Large holes in soil and soft rock can be drilled rapidly
and inexpensively by mechanized auger drilling. The major advantages of this method
are as follows: (I) a very high rate of penetration can be achieved; (II) a large spoil is
obtained in short time; (III) no flushing medium is required; (IV) noise level is very
low. The common applications include, prospecting foundations tests, soil
reinforcements, fence posts, and some type of well drilling and blast holes [19].
Augers are usually hand-held or truckmounted drills,which have rodswith “spiral
shapedflights”used tobringsoftmaterial to thesurface. Augersvary insize, from
those to dig fence post sized holes, up to large ones over a meter in diameter. Augers
are light drills and are incapable of penetrating either hard ground or boulders [28].
20
2.3.4 Diamond drilling
Diamond core drills are exploratory machine primarily, but also fill a gap in
blast hole drilling not converted by other classes. Also core drilling can be utilized
for: Sampling in situ, drainage of mine workings, ventilation, sand filling, rock
mechanics instrumentation, gas and oil drilling, proving the quality of structural
concrete of dam sites, rock bolting and drill holes for ground stabilization. Diamond
drills are used for holes varying from few centimeters to many thousands of meters in
oil well drilling [5].
To produce a core sample, diamond drilling is chosen because they are used as
surface rigs and underground, by the oil, civil engineering, quarrying and mining
industries and for holes varying in depth from a few inches (cm.) to many thousands of
feet (meters) in oil well drilling [10, 19]. This drilling system is most versatile of all
the methods, and it is designed specifically for the resource exploration industry and to
collect a sample in the state that is found. Successful diamond drilling is both art and
science, that requiring the proper understanding of how to use drilling speed and
pressure, coolants, and drilling accessories to maximize production efficiency, drill life
and product quality [28, 42, 43, 44].
Diamond drilling techniques are used when precise, circular cuts are needed.
Holes of almost any diameter from 6mm for items such as anchor bolts up to 1.5 m for
pipe work are easily drilled. It is also commonly used for drilling holes to route cables
or place anchoring bolts, to install load carrying devices or dowel bars, or for analysis
of structures, rock or strata. Diamond core drills have super sharp bit teeth and long
bit life [45, 46].
Today there are two main types of diamond drilling [10]:
Standard or conventional diamond drilling.
Wire- line diamond drilling.
In the Conventional diamond drilling type the sample is cut by a diamond
armored drill bit, stored in the inner barrel of drill pipe and then the pipe is brought to
the surface and then the core is removed. But, in wire line diamond drilling, the most
widely used and time effect method, the inner tube is hoisted to the surface through the
21
drill rods without the need to remove or withdrawing the rods from the hole. Using a
device known as an overshot, this is lowered down the inside of the rods on a cable
and locks onto the top of the core tube. The action of the overshot locking onto the
core tube causes latches that hold the core tube in the core-barrel to be withdrawn thus
freeing the core tube so that it can be hoisted to the surface [10]
Polycrystalline diamond compact (PDC) bits have proved successful in drilling
soft to medium strength rock formations because they achieve high rates of penetration
(ROP), while also maintaining long bit life. The development process has progressed
so that today a large amount of footage is drilled with PDC bits [47].
Non-core drilling methods generally have the advantages of lower costs than the
core drilling methods. When the core is not required, a non-core drilling method is
preferable. Non –coring methods are mainly used for the following [48]:
Geophysical logging.
Obtaining samples for assay and metallurgical testing.
Defining ore contacts in extensive sedimentary deposits.
Drilling through thick section overburden, and
Hydrological testing.
2.3.5 Heavy rotary blast hole drilling
Rotary blast hole drills are widely used for overburden removal all over the
world. A typical example may be cited as that, more than 100 million m3
of over
burden blasted annually in five Turkish open pit mines with a total annual drilling
length of around 1.65 x106
m. The common blast hole diameters range from 38 to 48
mm.[49, 50].
In surface/quarry mining, large diameter drilling equipment gives a high
productivity rate. Heavy rotary blast hole drilling is far superior to down-the-hole or
percussive methods in broken ground and in ground consisting of alternating bands of
22
hard and soft rock or rock with substantial clay bonds. The advantages of this drilling
type are as the follows [48]:
It is preferable in many sedimentary rocks.
It is an alternative in hard rock; provided that the drills of adequate
large holes are acceptable.
It gives a wider range of hole size and may be used to greater depths
In“bad”grounditmaybethesoleeconomicalmethod[48].
The factors to be considered in selecting a rotary blast hole drill rigs are:
mounting, power source, rotation pull down system, air volume requirement, most
inclined drilling capability, dust system, water, foam injection and noise suppression
[47, 49].
2.3.6 Rotary- Percussive drilling
In this method the penetration of the drill bit occurs due to resultant action of
both percussive and rotary movements. The rotational movement applies free on the
bit end to break the bond, holding the rock particles, while percussive action produces
longitudinal impact on the rods resulting in penetration of bit driven into rock. Rotary
Percussive drilling hammers are applied with an impact power of about 15 to 20 KW.
The main shortcomings of this type are short bit life, low output, and dust formation
[48, 50]. The optimum productivity for this method is possible by combining
advantages of both rotary and percussion drilling. The percussive – rotary drill was
developed first by the Salzgitter Company and then by Hauser and Nusse &Grafer.
This type of drilling machine had been mainly used in underground works [51].
A rotary – percussive rock drill was tested for wear under dry conditions when
drilling granite. Granite caused more rapid wear of drill bits than other rocks.
Rotary- Percussion drilling method is applied in very hard rocks, such as granite, the
only way to drill a hole is to pulverize the rock, using a rapid - action pneumatic
hammer,oftenknownasa“down-the-holehammer”(DTH).Compressedairisneeded
to drive this tool. The air also flushes the cuttings and dust from the borehole.
23
Rotation of 10-30 rpm ensures that the borehole is straight, and circular in cross-
section. The advantages of rotary-percussion drilling are: drill hard rocks, possible to
penetrate gravel, fast, and operation is possible above and below the water-table. But
the disadvantages of this method are: higher tool cost than other tools of drilling
methods, air compressor required, and requires experience to operate and maintain.
[52, 53]. The prediction of the penetration rate (PR) of rotary – percussive drill is very
important in mine planning. Total drilling costs could be estimated by using
prediction equations to select the drilling rig type, which is best suited for given
conditions. The drillability of rocks depends on many factors. Bit type and diameter,
rotational speed, thrust, blow frequency and flushing are controllable parameters [54].
Table (2.1) shows drilling methods for the various ground conditions [48].
Table 2.1: Drilling methods for the various ground conditions [48].
Rock type Drilling method Remarks
Soil,
sand/gravel
Auger
Rotary
Sometimes temporary casing required
Temporary casing or mud additives required.
Soil, silty/clay Auger
Rotary
Mostly best choice
Temporary casing or mud additives required.
Rock, medium
hard
Rotary
DTH
Roller bit, sometimes needs mud additives
Large compressor required.
Rock, hard to
very hard
Rotary
DTH
Top hammer
With rock bit or hard- metal insert button bit, very slow.
Large compressor required.
Special equipment, depth range to 70ms.
Rock, core
sampling
Diamond Mostly best choice for sampling in site, quarry and
geological investigation, proving the quality of structural
concrete.
Rock under
over burden
ODEX
Or similar
In combination with DTH.
The following general guidelines are used to determine which drilling method is
necessary for the drilling operation [48]:
For small diameter shallow blast holes, jackhammer or truck mounted drills
are usually used.
For blast holes up to 6 inches and about 50 feet deep, track mounted,
percussion drills are used.
24
For drilling holes from 6 to 12 inches, from 50 to 300 feet deep, rotary blast
hole drills are usually the best choice, but this is affected by the type of rock.
If cores from 3 inches up to 8 inches are desired, diamond drilling is the best
choice. The diamond drill can drill faster and is not limited by the direction.
2.4 Major factors influencing penetration rate
Penetration rate is the factor that has a major influence on the productivity and
consequently, on the overall cost per unit, and is influenced by geological parameters,
machine parameters and operating parameters [55].
Drilling rate is one of the main factors affecting drilling cost. The overall
performance of any drill bit is complex and is affected by numerous factors which
include operating parameters of the bit, formation properties, bit design and type, wear
characteristics, drilling fluid properties and flow mechanics, hole characteristics,
capacity of the drilling machine, time, climate and operator or crew efficiency.
However, the principal factors that require consideration in predicting drilling rates are
the operating parameters of the drill bits and the penetrated rock characteristics [47].
The most important factors that affect the rate of penetration are [19]:
Weight on bit (thrust) and rotary speed,
Bit type and condition,
Rock properties (Formation characteristics), and
Fluid properties (circulation).
One can conclude that each rock type has different drillability values depending on
the drilling system and the bit used. Therefore, the only acceptable way to determine
the drillability of a rock is to drill it. Drillability values have, therefore, been obtained
using rotary drilling system for a wide range of rock types from different areas [11].
25
2.4.1 Weight on bit (WOB) and Rotary speed (RPM)
Weight on bit, WOB, is amount of the axial force applied to the bottom-hole.
Since bit weight and rotational speed considerations are interrelated i.e., an increase in
one usually necessitates a reduction in the other for minimum cost drilling. In soft
formation doubling of either bit weight or rotational speed will double the drilling rate.
In hard formation when bit weight and rotational speed are increased the rate of
penetration is increased too [19].
The required thrust depends upon the drilling method, the size of bit, the
sharpness of cutting edges, the resistance of rock and pressure of flushing medium that
tends to lift the bit off the rock. In rotary drilling, penetration speed is directly
proportional to the applied thrust. In spite of this there are limitations to the degree of
thrust that can be applied because over thrusting tends to cause rods to bend and hole
to deviate. On the other hand, under thrusting produces excessive bit wear in all forms
of rotary drilling, diamond, drag and roller bits [11].
2.4.2 Bit type and Condition
The bit type selected and the design characteristics of the bit have a significant
influence on ROP. Tooth length; number of cutters; cutter exposure or blade standoff;
size, shape, surface, and angle of the cutter are some of the many bit characteristics
which affect ROP and bit performance. Bit condition, specifically the bit wear state,
has an influence on the effectiveness of drilling; and increased wear reduces ROP and
bit performance [19, 48].
Selection of bit type has a large effect on the penetration rate. It plays an
important role to determine the performance of a drill with respect to efficiency.
Continuous research and experimentation have resulted in bit designs that provide a
specific bit types for a wide range of drilling conditions. These bits are classified into:
diamond bits, carbide bits saw tooth and rotary drill bits. Diamond bits can be
classified according to the type of rock to be drilled as: surface-set diamond bits,
26
impregnated diamond bits, polycrystalline diamond (PDC) and strata-pax drill blank.
According to the profile and design of the crown: coring and non-coring bits.
According to the drilling technique used: conventional drilling diamond bits and wire
line- drilling bits. The carbide rotary drill bits are classified into coring and non-coring
bits and they include: standard carbide bits, pyramid carbide bits and saw tooth bits.
Non- coring includes: roller and drag bits. The following Fig. 2.5 illustrates the
different types of drilling bits [19].
Figure 2.5: different types of drilling bits [19]
2.4.3 Rock properties
Rock properties are the unalterable factors that affect the rate of penetration.
Fundamental studies in rock mechanics led to better define rock properties. Formation
Bit Types
Rotary bits Percussive bits Diamond bits
Roller Drag Blade Button type Core Non-core
Blade Replaceable
Three cones Two
Cross bits Flat with a
number of
TC inserts
X-bits
Chisel bits
Impregnated
Surface-set
Polycrystalline
Concave Taper Pilot
27
properties that have been investigated are: compressive strength, hardness and
abrasiveness, overburden pressure, porosity, pore pressure, permeability, elasticity and
rock temperature. As a general rule, rock strength and over burden pressure increase
with depth. At greater depths, the rocks are more compact and therefore, more difficult
to be drilled. The hardness and abrasiveness characteristics of a rock have an influence
on bit life. In general, penetration rate varies inversely with Compressive strength and
is directly proportional to porous or permeable rock formations [19, 47, 48].
The elastic limit and ultimate strength of the formation are the most important
formation properties affecting ROP; however, the mineral composition of the rock can
change the ROP. For example, Rocks containing hard and abrasive minerals can cause
rapid dulling of the bit teeth, and gummy clay minerals can cause the bit to ball up.
The rock would be drilled very slowly in either case [11].
2.4.4 Fluid properties (Circulation)
The properties of the drilling fluid highly affect ROP. Density, flow properties,
solids content and size distribution, and chemical compositions are some of the
properties, which have a high influence on bit performance. If a dense fluid such as
mud or water is used for circulation, the formation drilled is influenced by a
hydrostatic pressure that depends on hole depth and drilling fluid density [48, 56].
Water is the most commonly used drilling fluid, but when drilling in soft rocks,
it is found to be too erosive. In such cases mud, which consists of a bentonite-water
mixture is used. In blast hole drilling direct air flushing is used with three-cone rolling
bits because of greater penetration rate and longer life. To reduce airborne dust a
small amount of water is injecting into air stream. This air mist mixture agglomerates
the fine dust into large pellets, which can be collected more easily. The principle
functions of a drilling fluid are: carry cuttings from the hole, cool and clean the bit,
reduce friction and maintain stability of uncased holes [19].
28
2.5 Automatic optimization of drilling techniques
Optimization means obtaining optimal results by lowest drilling costs; many
experiments on drilling in different rock types were carried out in the laboratories and
in situ. These experiments have shown that the weight on bit (thrust), physical and
mechanical properties of the drilled rocks and rotation speed of the tool are the most
important factors affecting the optimization of the drilling system. The optimization
can be judged by considering some factors, including penetration rate, total time for
hole completion, percentage of core recovery, bit life, etc. It has been shown from the
previous experience and works on the drill rig that the thrust plays a major role in
affecting penetration rates and may be treated as the governing control parameter [48].
2.5.1 Drill productivity evaluation by monitoring
During the last decades, the use of microprocessor-based drill monitoring
equipment to permit scanning, measurement, processing and storage of drill
performance parameters has become an accepted technique. The equipment used for
monitoring was an integrated part of the drill rig. The drilling information was
collected for a period of time. During this time data were sampled, hours, minutes,
and seconds (h: m: s), drill-hole depth (m), penetration rate (m/min), rotation speed
(rev/min), thrust (KN), air percussive pressure (bar), and torque pressure (bar), were
recorded for every 10 mm of hole length. Improvement in the drilling cycle, resulting
in improved overall production. The monitored drill parameters were stored on an
ordinary 3.5 inch diskette in the monitoring instrument, which was mounted in the
operator’scabinofthedrillingrigandthediskettesweretransferredtotheofficefor
analysis [19, 48, 57].
2.5.2 Rock characterization by monitoring
Researches have shown that measurements of specific energy, in conjunction with
accurately known drill depths, can be used to indicate the location of strata boundaries
and voids. Percussive drill monitoring can provide detailed information on hardness,
fracturing and weathering of the rock mass. The major advantage is the speed at
29
which the result can be presented. Since, the data are monitored in digital form and
analysis on an ordinary computer only takes a few minutes, the method can be made as
an integrated part in a decision process. The recorded parameters are: time when data
are recorded, drill hole length, penetration rate, rotation speed, thrust, air pressure and
torque pressure. This technique has been used successfully in several mining and
underground applications, providing rock properties with high agreement with the
observed conditions [19, 58].
2.5.3 Measurement While Drilling (MWD)
Today all interpretation is done by software, allowing information to be
delivered to different centers in the mine. Measurement while drilling (MWD)
techniques can provide a useful tool to aid drill and blast engineers in open cut mining
[19]. Fig. 2.6 shows the measuring while drilling system (MWD) [59].
Driller
Driller software
Data reduction, analysis& display
Figure 2.6: schematic representation of the MWD system [59]
A high – speed data link provides faster communication from downhole
instruments to the surface and back again. Many aspects of the drilling process will
High Speed Data Link
MWD
30
improve if downhole and surface data were acquired and processed in real – time at
the surface, and used to guide the drilling operation. The main focus of this program is
to demonstrate the value of real- time data for improving drilling. While high - rate
transfer of down- hole data to the surface has been accomplished before.
Demonstration of the benefits of measuring while drilling (MWD) based on a high-
speed data link will convince the drilling industry and simulate the flow of private
resources into the development of an economical high – speed data link for geothermal
drilling applications to control and improve drilling performance. Real – time data
achieves many benefits, such as, improving rock penetration rates, bit life, improved
drilling pressure, reducing drilling costs and gives us a better understanding of the
drilling process [59].
2.5.4 Rotary and Percussive drilling rate prediction models
Programming system facilitate rapid driving models and prediction equations,
for rotary – percussive drilling penetration rate. Prediction of the penetration rate is
very important in mine planning. Total drilling costs could be estimated by using
prediction equations. Also, one could use prediction equation to select the drilling rig
type, which is best suited for given conditions. The drillability of rocks depends on
many factors. Bit type and diameter, rotational speed, thrust, blow frequency and
flushing are the controllable parameters. On the other hand, the parameters such as
rock properties and geological conditions are uncontrollable parameters. Drillers try to
develop a model for drilling and blasting in open pits and quarries [60, 61, 62].
Prediction models seem to be promising and as per expectance. The recorded
test values show that the model equations are well suited to describe and distinguish
the all operating properties [62]. Today's, computer drilling simulator has been
modified and spreads all over the world. The starting point is to obtain field data that
is needed for simulation, these data were used as input for simulator in order to have
predictions of the rate of penetration as an output [63, 64, 65]. Environmental,
archeological and biological factors may place restriction or conditions on a site of
drilling. Disposal cleared material should be arranged and the use of drilling requires
31
planning and implementation prior to drilling. Developing an exploration program
requires a thorough knowledge of the design requirements, site conditions, drilling
equipment requirements and capabilities and rock properties. Drilling procedures
needed are based on the drilling sampling requirements [66].
The Ultrasonic / Sonic drilling / Coring (USDC) device opens new possibilities
for future sample return mission. Unlike conventional drilling rigs, USDC can core
even the hardest rocks. The device can be duty cycled without significant loss of
efficiency, this facilitating operation under low power. Unlike conventional drills, the
drilling head of the USDC does not have any gears or motors, it has only two moving
parts, and, thus, can be easily adapted to operations in a very wide temperature ranges.
The drilling tool does not require sharpening, its drilling speed does not decline with
time, and it does not rotate. USDC can core arbitrary cross- sections (square, round,
hexagonal), since conventional rotary drills and cores cannot meet these capabilities of
USDC [67].
2.6 Future perspective of drilling techniques
In 2001 a number of leaders from drilling industries met in Washington D.C to
discuss and develop a vision for future of drilling. The vision for 2020 includes [19]:
2.6.1 Safety and health
Use of autonomous drilling systems tools that will reduce the number of
workers needed in hazardous environments. These systems may include
robotics, remotely controlled technologies and computers.
Improved worker training to ensure safer drilling operations.
Reduce or eliminate noise, dust and vibration thereby benefiting both workers
and surrounding area.
In- situ management of toxic and waste materials thereby eliminating associated
environmental and health issues.
Drilling without the use of mud to avoid cleanup and disposal costs.
32
Unconventional drilling methods such as lasers, percussion drilling, microwave
drilling and deep sea drilling.
2.6.2 Productivity
Improvements in productivity will require an integrated systems approach to
drilling operations. The drilling industry in 2020 will be characterized by [19]:
Increased production efficiency with faster penetration rates allow for a greater
number of exploration and production drill holes.
Increased safety and efficiency with line-advancing or zero casing systems for
drill holes.
Lower costs and environmental impacts with In-situ extraction and processing
equipment.
Increased efficiency and production with sensing and imaging technologies
create smart drilling systems.
Smaller equipment and rigs, alternative to lubricants, or equipment that does
not need lubricants.
33
CHAPTER 3
3 STEPS OF THE EXPERIMENTAL WORK AND PROCEDURES
This chapter gives a brief description of the experimental procedures and
drilling data, according to the following general program of experimental work as
shown in Figure 3.1.
Cutter Type Rock Type Rotary Speed, WOB, Rock Drilling
(RPM) Kg properties result
Figure 3.1: Program of the experimental work
New
Diamond Bit
Mankabad
Limestone
Used
Diamond Bit
Minia
Limestone
Assiut
Limestone
Issawyia
Limestone
Zaraby
Limestone
Black Marble
White Marble
Pink Granite
Black
Granite
300
RPM
1000
RPM
15
Kg
30
Kg
45
Kg
60
Kg
390
Kg
480
Kg
570
Kg
ρ
gm/cm3
Р
%
бc
MPa
бt
MPa
бsh
MPa
μ
ROP
Cm/min.
SE
MPa
T
N.m
UCS/SE
MPa
34
Where:
The experimental work of the present investigation consists of two parts:
1. The first part is the determination of rock properties and the relation between
these properties and the penetration rate of the rock.
2. The second part is the drilling operations of the rock and how they are affected
by drilling conditions such as thrust acting on the rock, rotational speed of the
drill and bit conditions. ROP, SE, T and UCS/SE are the most important
parameters affecting the drilling operation. They are taken into consideration in
this thesis as a tool to predict the type of drilled rock.
3.1 Rock properties
Samples of rocks were collected from different localities as shown in location
map, Figure 1.1. Sedimentary, metamorphic, and igneous rocks are chosen for this
study. Sedimentary rocks are represented by five samples of limestone from three
different localities: the first type of limestone formation is from Assiut cement
company quarry, the second type is from Beni-Khaled, Minia, the third type is from
Mankabad quarry, north Assiut, the fourth type is from Zaraby quarry, the last type is
from Issawyia, east Sohag. Metamorphic rocks are represented by two types, White
and Black marbles are from Wadi-El-Miah, Eastern Desert. Igneous rocks are
WOB Specific weight on bit, Kg
ρ Density, gm/cm3
% P Porosity
Compressive strength, Mpa
Tensile strength, MPa
Shear strength, Mpa
μ Coefficient of internal friction
ROP Rate of penetration, cm/min.
SE Specific energy, MPa
T Torque, N.m.
⁄ Uniaxial compressive strength / Specific energy
35
represented by two types, Pink and Black granites are from Wadi- Allaqi, Aswan.
Selection of rock types was planned to meet the conditions upon which the results can
be discussed. Blocks about 20x15x10cm sizes formed by diamond saw from each type
of rock for the drilling tests. The most important physical and mechanical properties
of the tested rocks such as density, porosity, compressive strength, tensile strength, and
coefficient of internal friction (μ)were determined. Table 3.1 contains the average
value for each respective test together with its standard deviation.
Table 3.1: Physical and mechanical properties of the tested rocks
3.2 Drilling operations
In this study, blocks measuring 20x15x10 cm are formed by diamond saw from
each type of rock for the drilling tests. Diamond core drilling is applied for the tests.
The coring bits used have thin walled impregnated diamond type, the used bit has
inner diameter 40 mm and outer diameter 45 mm, the produced cores measure about
38 mm.
The load on the bit is applied by using hanging weights fixed on a movable
wheel by wire rope. The wheel is fixed on to the machine gear axis. Hence, the load
is transferred onto the bit. This transfer load is checked up and calibrated using
proving ring. Because of the important effect of load on the drilling operations,
drilling tests have been conducted using different loads.
Rock
Type
Density
(
⁄ )
Porosity
%
Compressive
strength,
MPa
Tensile
Strength,
MPa
Shear
Strength,
MPa
Coefficient
of Friction,
(µ)
Mankabad Limestone 1.72±0.0096 24.31±0.44 6.34±0.193 1.79±0.049 0.64±0.02 0.675
Minia Limestone 1.85±0.006 24.04±0.44 9.19±0.283 3.88±0.119 2.56±0.20 0.435
Assiut Limestone 2.18±0.0115 19.89±0.524 12.23±0.707 5.004±0.25 8.62±0.59 0.499
Issawyia Limestone 2.19±0.0137 15±3.26 16.02±0.905 6.77±0.383 5.02±0.21 0.488
Zaraby Limestone 2.39±0.0132 14.44±0.452 27.05±1.23 7.48±0.56 9.52±0.56 0.649
Black Marble 2.70±0.025 3.17±0.088 40.55±0.424 8.47±0.15 13.86±0.92 0.869
White Marble 2.74±0.0038 1.41±0.178 51.33±0.174 9.05±0.70 10.5±0.87 0.9004
Pink Granite 2.82±0.0161 1.29±0.25 74.88±3.78 9.75±0.513 11.02±0.66 0.93
Black Granite 2.90±0.0127 1.16±0.043 95.35±6.68 12.38±0.482 13.25±1.23 0.97
36
Data and conditions of drilling experiments and rocks under test were recorded.
Applied load, actual speeds, length of borehole, and time of drilling are recorded as
results of drilling. These results are used to calculate the drilling rate and the average
drilling rate at specific load of the rock, which are influenced by geological
parameters, machine parameters, and operating parameters.
Three trials were carried out for a particular weight on bit (WOB). Selection of
the WOB ranges for the bit was made by applying minimum WOB where the bit was
just capable of drilling the rock and maximum WOB just below the point where the
drill commenced to stall or showed “distressed” drilling. Five to Seven WOB
increments for each rock were selected between these limits. All drilling trials were
carried out at 300 rpm and 1000 rpm motor speed. The drilling speed value was the
unloaded speed; however, the speed is reduced over a small range with increasing
torque.
The drilling machine was a drill press modified to permit different applied
thrust or axial load, as shown in Figure (3-2). The drill speed can be adjusted to be
300 and 1000 rpm, by changing the variable speed drive. To apply the required axial
thrust on the bit, the feeding handle was replaced by a wheel used as a lever arm
(400mm) for dead weights. The drilling tool used in this work was diamond bits 45
mm (4.5 cm) diameter. The bit was attached to the main spindle of the drill. For
cooling the bit and removing the cuttings, water was used as a flushing media. Water
passes through a ring at a rate at a rate of 8 ⁄ (Q = 2.4 S), where "S" is the gap
cross- sectional area in . This arrangement resulted in the application of an axial
force to the drill while permitting the weights to remain stationary, thus ensuring
constant force acting downwards on the drill. Figure 3.3 represents a schematic
representation of the drilling machine. With the help of a proving ring, it becomes
possible to determine the actual load acting on the bit. Because the speeds taken from
the drill counter are misleading, the actual rotational speed at any test condition was
determined by a speedometer to calibrate the speed of tests. Water is used as cooling
37
and flushing media. The flow rate of water into coring bit equals about 8 liters/minute
calculated simply as follows:
Q = 2.4 S, where S is the gap cross- sectional area in .
Figure 3.2: Diamond core drilling machine
38
Figure 3.3: Schematic representation of the drilling machine [11].
1
2
3
4
56
7
8
9
10
11
12
13
14
1- Drilling press motor.
2- Gears,.........etc.
3- Depth measuring vernier.
4- Spindle.
5- Micro-bit.
6- Cooling water.
7- Fixed angle support.
8- Table.
9- Base.
10- Load.
11- Specimen.
12- Lever arm for load.
13- Flexible rope.
14- Free wheel to rotate
with hand.
39
3.3 Experimental data of drilling tests
The experimental data of operating parameters are presented in the following
Tables 3.2 to 3.15.
Table 3.2: Data of the drilling parameters in Mankabad limestone, Assiut
Weight
On bit,
Kg.
V1 = 300 rpm V2 = 1000 rpm
New bit Used bit New bit Used bit
Torque,
N.m
ROP,
cm/min.
Es,
MPa
Torque
N.m
ROP,
cm/min
Es,
MPa
Torque
N.m
ROP,
cm/min.
Es,
MPa
Torque
N.m
ROP,
cm/min
Es,
MPa
15 2.20 2.10 124.20 2.11 1.35 185.3 2.20 4.02 216.4 2.11 2.30 360.7
30 4.30 4.36 116.90 4.21 2.79 178.8 4.30 8.36 203.2 4.21 4.72 351.5
45 6.50 7.05 109.30 6.32 4.24 176.8 6.50 13.18 194.9 6.32 7.39 336.8
60 8.60 9.83 103.70 8.42 5.85 170.5 8.60 19.53 174 8.42 10.18 326.0
75 10.80 2.7 0 474.10 10.53 2.63 473.2 10.80 7.21 519.8 10.53 6.53 635.2
Table 3.3: Data of the drilling parameters in Beni-Khalid- Samalout limestone, Minia
Weight
On bit,
Kg.
V1 = 300 rpm V2 = 1000 rpm
New bit Used bit New bit Used bit
Torque,
N.m
ROP,
cm/min.
Es,
MPa
Torque
N.m
ROP,
cm/min
Es,
MPa
Torque
N.m
ROP,
cm/min.
Es,
MPa
Torque
N.m
ROP,
cm/min
Es,
MPa
15 1.4 0.76 218.32 1.4 0.63 263.4 1.4 1.65 335.2 1.4 1.23 677.7
30 2.8 2.14 155.07 2.7 1.36 235.3 2.8 4.42 250.3 2.7 2.75 387.9
45 4.2 3.92 126.98 4.1 2.19 221.9 4.2 6.85 242.2 4.1 4.52 358.4
60 5.6 6.11 108.63 5.4 2.93 218.4 5.6 9.53 232.1 5.4 6.13 348.0
75 6.9 7.92 103.25 6.8 4.13 195.2 6.9 13.16 207.1 6.8 8.2 327.6
90 8.3 10.21 96.35 8.1 5.37 178.7 8.3 16.32 200.9 8.1 10.92 293.0
105 9.7 12.16 94.54 9.5 7.3 154.3 9.7 13.67 280.33 9.5 8.65 433.9
120 11.1 6.47 203.33 10.9 4.17 309.8 11.1 - - 10.9 - -
40
Table 3.4: Data of the drilling parameters in Assiut cement company quarry limestone, Assiut
Weight
On bit,
Kg.
V1 = 300 rpm V2 = 1000 rpm
New bit Used bit New bit Used bit
Torque,
N.m
ROP,
cm/min.
Es,
MPa
Torque
N.m
ROP,
cm/min
Es,
MPa
Torque
N.m
ROP,
cm/min.
Es,
MPa
Torque
N.m
ROP,
cm/min
Es,
MPa
15 1.60 0.64 296.30 1.60 0.52 364.7 1.60 1.08 585.3 1.60 0.7 902.7
30 3.20 1.92 197.50 3.10 1.08 340.2 3.20 2.53 499.7 3.10 2.11 580.4
45 4.80 3.24 175.60 4.70 1.73 322.0 4.80 4.27 444.1 4.70 3.68 504.6
60 6.40 5.33 142.30 6.20 2.75 267.2 6.40 6.12 413.1 6.20 5.56 440.5
75 8.00 7.00 135.40 7.80 3.86 239.5 8.00 8.80 359.1 7.80 7.61 404.9
90 9.50 9.53 118.10 9.30 5.21 211.6 9.50 11.25 333.6 9.30 10.14 362.3
105 11.10 2.71 485.40 10.90 2.42 533.8 11.10 6.78 646.8 10.90 5.29 814.0
Table 3.5: Data of the drilling parameters in Issawyia limestone, east Sohag
Weight
On bit,
Kg.
V1 = 300 rpm V2 = 1000 rpm
New bit Used bit New bit Used bit
Torque,
N.m
ROP,
cm/min.
Es,
MPa
Torque
N.m
ROP,
cm/min
Es,
MPa
Torque
N.m
ROP,
cm/min.
Es,
MPa
Torque
N.m
ROP,
cm/min
Es,
MPa
15 1.60 0.58 327.0 1.50 0.46 386.5 1.60 0.98 645.0 1.50 0.62 955.8
30 3.10 1.42 258.7 3.00 1.00 355.6 3.10 2.37 516.7 3.00 1.97 601.6
45 4.70 2.52 221.0 4.60 1.62 336.5 4.70 4.98 372.8 4.60 3.13 580.6
60 6.20 3.63 202.4 6.10 2.62 275.5 6.20 8.19 299.1 6.10 5.21 462.5
75 7.80 4.73 195.4 7.60 3.77 238.7 7.80 10.83 284.5 7.60 7.18 418.2
90 9.30 6.60 167.0 9.10 4.87 221.5 9.30 13.32 275.8 9.10 9.68 371.4
105 10.90 3.50 369.1 10.70 2.42 524.0 10.90 5.50 782.9 10.70 4.62 915.0
41
Table 3.6: Data of the drilling parameters in Zaraby limestone, Assiut
Weight
On bit,
Kg.
V1 = 300 rpm V2 = 1000 rpm
New bit Used bit New bit Used bit
Torque,
N.m
ROP,
cm/min.
Es,
Mpa
Torque
N.m
ROP,
cm/min
Es,
Mpa
Torque
N.m
ROP,
cm/min.
Es,
Mpa
Torque
N.m
ROP,
cm/min
Es,
Mpa
15 2.10 0.47 529.5 2.02 0.40 598.5 2.10 0.93 892.0 2.02 0.60 1330
30 4.10 0.98 495.8 4.05 0.87 551.7 4.10 2.30 704.2 4.05 1.76 909.1
45 6.20 1.67 440.0 6.07 1.44 494.6 6.20 3.58 684.2 6.07 2.83 847.4
60 8.30 2.52 390.3 8.10 2.12 452.8 8.30 5.16 635.4 8.10 4.71 679.4
75 10.40 3.37 365.7 10.12 2.85 420.8 10.40 7.54 544.9 10.12 6.92 577.7
90 12.40 4.22 348.2 12.15 3.67 392.4 12.40 11.26 435.0 12.15 9.13 525.7
120 14.50 2.96 664.6 16.20 2.15 893.0 14.50 4.97 1153 16.20 4.11 1154
Table 3.7: Data of the drilling parameters in Black marble, Wadi El-Miah, Eastern Desert
Weight
On bit,
Kg.
V1 = 300 rpm V2 = 1000 rpm
New bit Used bit New bit Used bit
Torque,
N.m
ROP,
cm/min.
Es,
MPa
Torque
N.m
ROP,
cm/min
Es,
MPa
Torque
N.m
ROP,
cm/min.
Es,
MPa
Torque
N.m
ROP,
cm/min
Es,
MPa
30 5.50 0.79 825.13 5.40 0.62 1033 5.50 2.02 1077 5.40 0.92 2319
45 8.30 1.55 634.65 8.10 1.25 768.0 8.30 3.50 936.9 8.10 1.86 1720
60 11.10 2.37 555.09 10.80 2.00 640.0 11.10 4.95 885.9 10.80 2.61 1635
75 13.90 3.25 506.89 13.60 2.77 581.9 13.90 7.33 749.2 13.60 5.10 1054
90 16.60 4.11 478.69 16.30 3.56 542.7 16.60 10.33 634.9 16.30 6.86 937.3
105 19.40 2.38 966.08 19.00 1.97 1143 19.40 5.40 1419 19.00 3.39 2214
42
Table 3.8: Data of the drilling parameters in White marble, Wadi El-Miah, Eastern Desert
Weight
On bit,
Kg.
V1 = 300 rpm V2 = 1000 rpm
New bit Used bit New bit Used bit
Torque,
N.m
ROP,
cm/min.
Es,
MPa
Torque
N.m
ROP,
cm/min
Es,
MPa
Torque
N.m
ROP,
cm/min.
Es,
MPa
Torque
N.m
ROP,
cm/min
Es,
MPa
30 5.70 0.68 993.5 5.60 0.57 1164 5.70 1.43 1575 5.60 0.81 2731
45 8.60 1.15 886.31 8.40 1.05 948.2 8.60 2.68 1267 8.40 1.70 1952
60 11.50 2.24 608.47 11.20 1.54 862 11.50 4.28 1062 11.20 2.53 1749
75 14.40 3.12 547.01 14.00 2.09 793.9 14.40 6.18 920.5 14.00 4.42 1251
90 17.20 4.00 509.63 16.90 2.76 725.7 17.20 7.66 887.1 16.90 5.78 1155
105 20.11 1.86 1281.4 19.70 1.83 1276 20.11 5.32 1493 19.70 3.20 2432
Table 3.9: Data of the drilling parameters in Pink granite, Aswan
Weight
On bit,
Kg.
V1 = 300 rpm V2 = 1000 rpm
New bit Used bit New bit Used bit
Torque,
N.m
ROP,
cm/min.
Es,
MPa
Torque
N.m
ROP,
cm/min
Es,
MPa
Torque
N.m
ROP,
cm/min.
Es,
MPa
Torque
N.m
ROP,
cm/min
Es,
MPa
90 22 0.4 5277.0 21.5 0.3 6874.2 22 0.9 7817.8 21.5 0.45 15275.7
120 29.4 0.71 3962.9 28.7 0.43 6394.6 29.4 1.35 6947.2 28.7 0.75 12220.5
150 36.7 1.06 3318.6 35.9 0.56 6137.6 36.7 1.78 6587.3 35.9 1.2 9547.3
180 44.1 1.51 2795.0 43.1 0.79 5220.9 44.1 2.35 5986.4 43.1 2.11 6515.7
210 51.4 2.09 2914.7 50.2 1.002 4802.3 51.4 3.14 5227.6 50.2 2.48 6467.5
240 58.7 1.65 3410.5 57.4 0.57 9647.9 58.7 1.88 9977.4 57.4 1.77 10356.4
43
Table 3.10: Data of the drilling parameters in Black granite, Aswan
Weight
On bit,
Kg.
V1 = 300 rpm V2 = 1000 rpm
New bit Used bit New bit Used bit
Torque,
N.m
ROP,
cm/min.
Es,
MPa
Torque
N.m
ROP,
cm/min
Es,
MPa
Torque
N.m
ROP,
cm/min.
Es,
MPa
Torque
N.m
ROP,
cm/min
Es,
MPa
90 - - - - - - 22.80 0.70 12867 22.30 0.30 29366
120 30.40 0.44 8188.3 29.70 0.34 10304 30.40 1.02 11774 29.70 0.63 18624
150 - - - - - - 38.00 1.42 10572 37.20 0.94 15699
180 - - - - - - 45.60 1.84 9790 44.60 1.43 12304
210 53.20 1.33 4740.6 52.10 0.78 7959 53.20 2.39 8794 52.10 1.77 11603
240 - - - - - - 60.80 2.89 8311 59.50 2.40 9794
270 - - - - - - 68.50 1.30 20816 66.90 1.12 23598
300 76.10 2.48 3636.7 74.40 1.20 7348 - - - - - -
390 98.90 3.43 3417.2 96.70 1.82 6297 - - - - - -
480 121.7 4.80 3004.8 119.0 2.63 5363 - - - - - -
570 144.5 2.60 6586.7 141.3 1.67 10028 - - - - - -
44
Table 3.11: Specific energy and UCS/SE for limestone at 300, and 1000 rpm and different
loads, new bit
WOB,
Kg
UCS,
MPa
SE, MPa (UCS/SE) ROP, ⁄
300 rpm 1000 rpm 300 rpm 1000 rpm 300 rpm 1000 rpm
15
6.34 124.2 216.4 51.05 29.3 21 40.2
9.19 218.32 335.2 42.09 27.42 7.6 16.5
12.23 296.3 585.28 41.28 20.90 6.4 10.8
16.02 326.95 645 49 24.84 5.8 9.8
27.05 529.5 892 51.09 30.33 4.7 9.3
30
6.34 116.9 203.2 54.23 31.2 43.6 86.3
9.19 155.07 250.3 59.26 36.7 21.4 44.2
12.23 197.5 499.7 61.92 24.47 19.2 25.3
16.02 258.7 516.7 61.93 31 14.2 23.7
27.05 495.8 704.2 54.56 38.41 9.8 23
45
6.34 109.3 194.9 58.01 32.52 70.5 131.8
9.19 126.98 242.2 72.37 37.94 39.2 68.5
12.23 175.6 444.1 69.65 27.54 32.4 42.7
16.02 221 372.8 72.49 42.97 25.2 49.8
27.05 440 684.2 61.48 39.54 16.7 35.8
60
6.34 103.7 174 61.14 36.44 98.3 195.3
9.19 108.63 232.1 84.6 39.6 61.1 95.3
12.23 175.6 413.1 69.65 29.61 32.4 61.2
16.02 202.4 299.1 72.49 53.56 36.3 81.9
27.05 390.3 635.4 61.48 42.57 25.2 51.6
75
9.19 103.25 207.1 89.01 44.37 79.2 131.6
12.23 135.4 359.1 90.32 34.06 70 88
16.02 95.4 284.5 81.99 56.31 47.3 108.3
27.05 365.7 544.9 73.97 49.64 33.7 75.4
90
9.19 96.35 200.9 95.38 45.74 102.1 163.2
12.23 118.1 333.6 103.56 36.66 95.3 112.5
16.02 167 275.8 95.93 58.09 66 133.2
27.05 348.2 435 77.69 62.18 42.2 112.6
45
Table 3.12: Specific energy and UCS/SE for Marbles at 300, and 1000 rpm and different
loads, new bit
WOB,
Kg
UCS,
MPa
SE,
MPa (UCS/SE)
ROP,
mm/min.
300
rpm
1000
rpm
300
rpm
1000
rpm
300
rpm
1000
rpm
30 40.55 825.13 1077.4 49.14 37.6 7.9 20.2
51.33 993.46 1574.72 51.67 32.6 6.8 14.3
45 40.55 634.65 936.86 63.89 43.3 15.5 35
51.33 886.31 1266.76 57.91 40.5 11.5 26.8
60 40.55 555.09 885.9 73.05 45.8 23.7 49.5
51.33 608.47 1061.49 84.36 48.4 22.4 42.8
75 40.55 506.89 749.16 80 54.1 32.5 73.3
51.33 547.01 920.53 93.84 55.8 31.2 61.8
90 40.55 478.69 634.85 84.71 63.9 41.1 103
51.33 509.63 887.08 100.7 57.9 40 76.6
Table 3.13: Specific energy and UCS/SE for Granites at 300, and 1000 rpm and different
loads, new bit
WOB,
Kg
UCS,
MPa
SE,
MPa (UCS/SE)
ROP,
mm/min.
300
rpm
1000
rpm
300
rpm
1000
rpm
300
rpm
1000
rpm
90 74.88 6518.3 9656.8 11.5 7.75 4 9
95.35 - 12867.3 - 7.41 - 7
120 74.88 4907.5 8603.3 15.3 8.7 7.1 13.5
95.35 8188.3 1174 11.6 8.1 4.4 10.2
150 74.88 4103.3 8145.1 18.3 9.19 10.6 17.8
95.35 - 10571.8 - 9.02 - 14.2
180 74.88 3461.3 7402.9 21.6 10.11 15.1 23.5
95.35 - 9790.4 - 9.74 - 18.4
210 74.88 2914.7 6466.8 25.7 11.58 20.9 31.9
95.35 4740.6 8793.6 20.1 10.84 13.3 23.9
300 74.88 - - - - - -
95.35 3636.7 - 26.2 - 24.8 -
390 74.88 - - - - - -
95.35 3417.2 - 27.9 - 34.3 -
480 74.88 - - - - - -
95.35 3004.8 - 31.7 - 48 -
46
Table 3.14: Average values of rate of penetration and specific energy at rotary speed 1000
rpm at different loads (WOB)
Weight
On bit,
Kg.
Limestone Marbles Granites
ROP,
mm/min.
SE,
Mpa
ROP,
mm/min.
SE,
MPa
ROP,
mm/min.
SE,
MPa
15 17.32 534.78 - - - -
30 40.50 434.82 17.25 1326.06 - -
45 65.72 387.64 30.9 1101.81 - -
60 97.06 350.74 46.15 973.7 - -
75 100.83 348.9 67.55 834.85 - -
90 130.38 311.33 89.95 760.97 8 11262.05
120 - - - - 11.85 10188.65
150 - - - - 16 9358.45
180 - - - - 20.95 8596.65
210 - - - - 27.65 7630.20
Table 3.15: Average values of rate of penetration and specific energy at rotary speed 300
rpm at different loads (WOB)
Weight
On bit,
Kg.
limestone Marbles Granites
ROP,
mm/min.
SE,
Mpa
ROP,
mm/min.
SE,
MPa
ROP,
mm/min.
SE,
MPa
15 9.1 299.05 - - - -
30 21.64 244.79 7.35 909.3 - -
45 36.8 214.58 13.5 760.48 - -
60 50.66 196.13 23.05 581.78 - -
75 65.5 144.68 31.85 526.95 - -
90 87.80 127.15 40.55 494.16 4 6518.3
120 - - - - 5.75 6547.9
150 - - - - 10.6 4103.3
180 - - - - 15.1 3461.3
210 - - - - 17.1 3827.65
300 - - - - 24.8 3636.7
390 - - - - 34.3 3417.2
480 - - - - 48 3004.8
47
CHAPTER 4
4 RESULTS AND DISCUSSIONS
In this chapter the effects of both weight on bit (WOB), rotary speed (RPM), bit
conditions on rate of penetration (ROP), and new drilling index (UCS/SE) were
discussed:
4.1 Effect of both weight on bit, rotary speed, and bit condition on rate of penetration
The effect of weight on bit (WOB) on the rate of penetration (ROP) is given in
Tables 3.2 to 3.10 and Figures 4.1 to 4.9. From these results it is clear that, the
increasing of the weight on bit (WOB) produces an increase in the rate of penetration
(ROP) up to a maximum point. However, a further increase in weight on bit (WOB)
causes little increase, or even a decrease in the rate of penetration (ROP) in all types of
tested rocks.
Figure 4.1: Relation between weight on bit (WOB) and rate of penetration (ROP) at
300 and 1000 rpm in Mankabad limestone, Assiut
0
5
10
15
20
25
10 20 30 40 50 60 70 80
Rat
e o
f p
enet
rati
on (
RO
P),
cm
/min
.
Weight on bit (WOB), kg
V1 =300 rpm (New bit)
V1=300 rpm (Used bit)
V2= 1000 rpm (New bit)
V2=1000 rpm (Used bit)
48
Figure 4.2: Relation between weight on bit and rate of penetration at 300 and 1000
rpm in Beni Khalid- Samalout limestone, Minia
Figure 4.3: Relation between weight on bit and rate of penetration at 300 and 1000
rpm in Assiut limestone
0
2
4
6
8
10
12
14
16
18
0 20 40 60 80 100 120 140
Rat
e o
f p
enet
rati
on (
RO
P),
cm
/min
.
Weight on bit (WOB), Kg
V1 =300 rpm (New bit)
V1=300 rpm (Used bit)
V2= 1000 rpm (New bit)
V2=1000 rpm (Used bit)
0
2
4
6
8
10
12
0 20 40 60 80 100 120
Rat
e o
f p
enet
rati
on (
RO
P),
cm
/min
.
Weight on bit (WOB), Kg
V1 =300 rpm (New bit)
V1=300 rpm (Used bit)
V2= 1000 rpm (New bit)
V2=1000 rpm (Used bit)
49
Figure 4.4: Relation between weight on bit and rate of penetration at 300 and 1000
rpm in Issawyia limestone, East Sohag
Figure 4.5: Relation between weight on bit and rate of penetration at 300 and 1000
rpm in Zaraby limestone, Assiut
0
2
4
6
8
10
12
14
0 20 40 60 80 100 120
Rat
e o
f p
enet
rati
on (
RO
P),
cm
/min
.
Weight on bit (WOB), Kg
V1 =300 rpm (New bit)
V1=300 rpm (Used bit)
0
2
4
6
8
10
12
0 20 40 60 80 100 120
Rat
e of
pen
etra
tion (
RO
P),
cm
/min
.
Weight on bit (WOB), Kg
V1 =300 rpm (New bit)
V1=300 rpm (Used bit)
V2= 1000 rpm (New bit)
V2=1000 rpm (Used bit)
50
Figure 4.6: Relation between weight on bit and rate of penetration at 300 and 1000
rpm in Black marble, Wadi El-Miah
Figure 4.7: Relation between weight on bit and rate of penetration at 300 and 1000
rpm in white marble, Wadi El-Miah
0
1
2
3
4
5
6
7
8
9
20 40 60 80 100 120
Rat
e o
f p
enet
rati
on (
RO
P),
cm
/min
.
Weight on bit (WOB), kg
V1 =300 rpm (New bit)
V1=300 rpm (Used bit)
V2= 1000 rpm (New bit)
V2=1000 rpm (Used bit)
0
2
4
6
8
10
12
20 40 60 80 100 120
Rat
e o
f p
enet
rati
on (
RO
P),
cm
/min
.
Weight on bit (WOB), Kg
V1 =300 rpm (New bit)
V1=300 rpm (Used bit)
V2= 1000 rpm (New bit)
V2=1000 rpm (Used bit)
51
Figure 4.8: Relation between weight on bit and rate of penetration at 300 and 1000
rpm in pink granite, Aswan
Figure 4.9: Relation between weight on bit and rate of penetration at 300 and 1000
rpm in Black granite, Aswan
0
0.5
1
1.5
2
2.5
3
3.5
70 90 110 130 150 170 190 210 230 250
Rat
e o
f p
enet
rati
on (
RO
P),
cm
/min
.
Weight on bit (WOB), Kg
V1 =300 rpm (New bit)
V1=300 rpm (Used bit)
V2= 1000 rpm (New bit)
V2=1000 rpm (Used bit)
0
1
2
3
4
5
6
0 100 200 300 400 500 600
Rat
e o
f p
enet
rati
on (
RO
P),
cm
/min
.
Weight on bit (WOB), Kg
V1 =300 rpm (New bit)
V1=300 rpm (Used bit)
V2= 1000 rpm (New bit)
V2=1000 rpm (Used bit)
52
Tables 4.1 & 4.2 give correlation equations of the relationship between rate of
penetration (ROP) and weight on bit (WOB) for all tested rocks at 300 rpm and
1000 rpm respectively.
Table 4.1: Correlation equations of the relationship between rate of penetration and
the weight on bit for all tested rocks at 300 rpm
Rock
type
New bit
*R
Used bit
*R
Mankabad
limestone
ROP= -0.0059 WOB2
+0.5785
WOB – 6.138
0.84
ROP= -0.0029 WOB2
+ 0.2992
WOB -2.894
0.88
Minia
limestone
ROP= -0.0013 WOB2
+0.258
WOB – 3.9745
0.90
ROP= -0.0004WOB2
+0.1079
WOB – 1.3875
0.89
Assiut
limestone
ROP= -0.0019WOB2
+0.284
WOB – 4.3014
0.80
ROP= -0.0007 WOB2
+0.1213
WOB – 1.6557
0.84
Issawyia
limestone
ROP= -0.0008WOB2
+0.1515
WOB – 2.0314
0.88
ROP= -0.0006WOB2
+0.1153
WOB – 1.6086
0.91
Zaraby
limestone
ROP= -0.0004WOB2
+ 0.0906
WOB – 1.0729
0.94
ROP= -0.0005WOB2
+ 0.095
WOB – 1.0514
0.90
White
marble
ROP= 0.0013 WOB2
+
0.208WOB – 4.0953
0.86
ROP= -0.0005WOB2
+
0.0928WOB – 1.8596
0.91
Black
marble
ROP= -0.001 WOB2
+0.1631
WOB – 3.5184
0.90
ROP= -0.0009WOB2
+ 0.1447
WOB – 5.9544
0.83
Pink
granite
ROP= -6 -5 (WOB2 )
+ 0.0289
WOB – 3.849
0.94
ROP= -5 -5 (WOB2)
+ 0.0194 WOB
– 3.124
0.84
Black
granite
ROP= -3 -5 (WOB)2
+ 0.0292
WOB – 2.978
0.90
ROP= -1-5 (WOB)2
+ 0.0123 WOB
-1.1416
0.90
53
Table 4.2: Correlation equations of the relationship between rate of penetration and the weight on
bit for all tested rocks at 1000 rpm
Rock
type
New bit
*R
Used bit
*R
Mankabad
limestone
ROP= -0.0101 WOB2
+ 1.0253
WOB – 10.7
0.84
ROP= -0.0038 WOB2
+ 0.4362
WOB – 3.962
0.92
Minia
limestone
ROP=-0.0011 WOB2 + 0.2944
WOB - 3.16
0.97
ROP=-0.0007 WOB2 + 0.185
WOB – 1.88
0.96
Assiut
limestone
ROP=-0.0013 WOB2 + 0.2479
WOB - 3.2329
0.91
ROP=-.0014 WOB2 + 0.2465
WOB – 3.5471
0.88
Issawyia
limestone
ROP=-0.0025 WOB2 + 0.4018
WOB –6.1329
0.86
ROP=-0.0014WOB2 +
0.2373WOB-3.5186
0.86
Zaraby
limestone
ROP=-0.0013 WOB2 + 0.2365
WOB – 0.625
0.82
ROP=-0.0013 WOB2 + 0.2257
WOB –1.403
0.85
White
Marble
ROP= -0.0015 WOB2
+ 0.2765
WOB -5.7787
0.93
ROP= -0.0012WOB2
+ 0.2129
WOB –3.991
0.87
Black
Marble
ROP=-0.0021 WOB2 + 0.3527
WOB –7.5261
0.84
ROP=-0.0014WOB2 + 0.2498
WOB -5.9544
0.83
Pink
Granite
ROP=-0.0001 WOB2 + 0.0509
WOB –3.2738
0.86
ROP=-.0001 WOB2 + 0.0486
WOB – 3.496
0.92
Black
Granite
ROP = 1.39 ln (WOB) – 5.50
0.70
ROP = 1.43 ln (WOB) – 6.09
0.79
*R: Correlation coefficient
As shown in Figures 4.1 to 4.9, limestone, marble, and granite need 15, 30,
and 90 kg as a minimum load to begin drilling respectively. The best load (WOB) is
the weight which gives maximum value of the penetration rate (ROP) and minimum
value of specific energy for rock drilling. From Figure 4.1 for Mankabad limestone,
the best weight on bit is 60 kg, that gives maximum value of rate of penetration
(ROP=4.6 cm/min.) at 300 rpm when using used bit, and (ROP=7.3 cm/min.) when
54
using new bit at the same rotary speed 300 rpm. And the rate of penetration at 1000
rpm for used bit is (ROP= 8.50 cm/min.) and is (ROP=14.50 cm/min.) with new bit at
1000 rpm.
Figure 4.2 shows that the best weight on bit required for drilling in Minia
limestone is (WOB= 105 kg) at 300 rpm which gives the highest rate of penetration
value (ROP= 5.6 cm/min.) for used bit and is (ROP= 9.2 cm/min.) for new bit at the
same rotational speed 300 rpm. When the drilling speed increases to 1000 rpm, and at
best weight (90 kg WOB) the rate of penetration is (ROP= 9.4 cm/min.) with used bit
and is (ROP = 13.6 cm/min.) with new bit .
Figure 4.3, gives the best weight on bit during drilling in Assiut limestone is 90
kg WOB, which gives (ROP = 3.6 cm/min.) for used bit and (ROP= 6.4 cm/min.) for
new bit both are at 300 rpm., but when the drilling speed is 1000 rpm the rate of
penetration for used and new bit respectively is 7.6 cm/min. & 8.6 cm/min.
Figure 4.4, shows the best load on bit wanted in drilling in Issawyia limestone
is 90 kg WOB, that gives maximum value of the penetration rate (ROP= 3.6 cm/min.)
for used bit and is (ROP= 4.87 cm/min.) for new bit both are at 300 rpm. When the
drilling speed becomes 1000 rpm the drilling rate is (ROP= 6.8 cm/min.) for used bit
and (ROP=9.68 cm/min.) for new bit.
Figure 4.5 shows the best load on bit for Zaraby limestone is 90 kg WOB,
which produces maximum value of penetration rate (ROP= 2.8 cm/min.) for used bit
and (ROP= 3.47 cm/min.) for new bit both are at 300 rpm, and when the drilling speed
is 1000 rpm the rate of penetration is (ROP= 6.4 cm/min.) for used bit and (ROP= 7.6
cm/min.) for new bit.
From these results and figures of all limestone rocks, we found that the
maximum value of rate of penetration at 60 kg WOB is in Mankabad limestone and
the minimum value is in Zaraby limestone at the same conditions (bit conditions,
drilling speed and WOB).
55
Rate of penetration at 60 kg WOB in Mankabad limestone is (1.61-2.05) times
than that in Minia limestone, and is (1.83-3.19) times than that of Assiut limestone,
and is (1.95-2.71) times than that of Issawyia limestone, and is (2.16-3.90) times than
that of Zaraby limestone, at both new and used bit for two different rotary speeds 300
&1000 rpm. This related to Zaraby limestone is most hard than all these tested
limestone.
Figure 4.6 & 4.7 show that the minimum load of 90 kg is required to begin
drilling in Black and White marble respectively. In Black marble at 90 kg WOB the
rate of penetration is (ROP= 1.03-1.35) times than that of White marble at 300 and
1000 rpm and for both used and new bit.
Figures 4.8 & 4.9 illustrate that the minimum load of 90 kg is required to begin
drilling in pink and black granite respectively. For pink granite, the best load on bit is
210 kg WOB (Fig.4.8) that gives rate of penetration (ROP= 0.75 cm/min.) for new bit
and (ROP= 1.8 cm/min.) for used bit both at 300 rpm, but at 1000 rpm the rate of
penetration is (ROP= 2.09 cm/min.) for new bit and is (ROP=2.48 cm/min.) for used
bit.
For black granite as shown in Figure 4.9, the best load of 480 kg is required to
give maximum value of penetration rate (ROP=4.8 cm/min.) for new bit and
(ROP=2.63 cm/min.) for used bit at 300 rpm. And the best load of 240 kg is required
to give maximum value of penetration rate (ROP=2.40 cm/min.) for used bit and (ROP
=2.8 cm/min.) for new bit at 1000 rpm. By comparing three categories of rocks, we
found that all figures illustrate that the highest value of penetration rate was obtained
during drilling in limestone by using small loads on bit than marbles and granites,
because the granites are most hard than marbles and limestone.
To show the effect of bit conditions on the rate of penetration (ROP), drilling
machine was set at nominal speeds at 300 and 1000 rpm for all the tests. For
Mankabad limestone, as shown in Fig. 4.1, the rate of penetration at 60 kg using new
bit is (1.68 -1.92) times at 300 and 1000 rpm than that using used bit respectively.
56
For Minia limestone, Fig. 4.2, gives the rate of penetration at 105 kg, using
new bit is (1.67) times than that at using bit at 300 rpm, and the rate of penetration at
90 kg at 1000 rpm when using new bit is (1.50) times than with used bit . For Assiut
limestone Fig. 4.3, gives the rate of penetration at 90 kg is (1.11-1.83) times at 300 and
1000 rpm than with used bit respectively.
For Issawyia limestone, Fig. 4.4 gives the rate of penetration at 90 kg, at 300
and 1000 rpm is (1.36-1.38) times than with using bit. For Zaraby limestone, Fig. 4.5,
gives the rate of penetration at 90 kg at 300 and 1000 rpm is (1.15-1.23) times that
when using used bit respectively.
For black marble, Fig. 4.6, the rate of penetration at 90 kg at 300 and 1000 rpm
is (1.15-1.51) times than with used bit respectively. For white marble, Fig. 4.7, the
rate of penetration at 90 kg at 300 and 1000 rpm is (1.33-1.45) times than with used bit
respectively.
For pink granite, Fig. 4.8, the rate of penetration at 210 kg at 300 and 1000 rpm
is (2.09-1.27) times than when using used bit respectively. For black granite, Fig. 4.9,
the rate of penetration at 480 kg at 300 rpm is (1.82) times than with used bit, and the
rate of penetration at 210 kg at 1000 rpm is (1.20) times than that with used bit.
4.2 Effect of both weight on bit, rotary speed and bit conditions on torque
The torque is a measure of resistive forces opposing rotation and is a function
of friction, cutting or shearing forces and abrasion at the bit/rock interface. Hence
with increasing WOB the friction resistance is increased and required greater torque,
being dependent upon the strength of the rock. For diamond drilling coring bit, the
normal pressure (WOB) can be assumed to be uniform over drilled annulus. Thus the
resisting torque over the total area of the annulus determined by [39, 47].
⁄
(4.1)
57
Where,
T = resisting torque, kgfm
Fv = applied thrust, kgf.
ro = outside radius, m
ri = inside radius, m
= Coefficient of friction
There is a linear relation between the two parameters (WOB & T) up to the
critical value or stalling conditions, the rate of penetration rises with increasing weight
on bit WOB at both two drilling speeds 300 and 1000 rpm for both two bit conditions.
Figures 4.10 & 4.11 show the relations between weight on bit (WOB) and torque (T),
one type from the three rock categories is given as an example representing constant
drilling speed and different bit conditions.
Figure 4.10: Relation between weight on bit and torque at 300 rpm using new bit, For
Zaraby limestone (Assiut), white (Wadi El-Miah Eastern Desert), and pink
granite (Aswan)
0
10
20
30
40
50
60
70
0 50 100 150 200 250 300
Torq
ue
(T),
N.m
Weight on bit (WOB), Kg
Zaraby Limestone
White Marble
Pink Granite
58
Figure 4.11: Relation between weight on bit and torque at 300 rpm using used bit, For
Zaraby limestone (Assiut), white marble (Wadi El-Miah Eastern Desert),
and pink granite (Aswan)
Table 4.3: Correlation equations of the relationship between Torque (T) and weight on bit
(WOB) at 300 rpm
*R: Correlation coefficient
4.3 Effect of weight on bit, rotary speed, and bit condition on specific energy
The drilling specific energy is very significant measure of drilling performance.
It is directly compatible with cost/meter, because it relates to the amount of energy
required to penetrate rock. Specific energy (SE) can also be used to quantify the
efficiency of rock working processes and to indicate bit conditions, rock strength and
rock hardness during drilling [56]. It is considered a good indication to judge the bit
performance and how it behaves in a particular rock. Specific energy can be defined,
0
10
20
30
40
50
60
70
0 50 100 150 200 250 300
To
rqu
e (T
), N
.m
Weight on bit (WOB), Kg
Zaraby Limestone
White Marble
Pink Granite
Rock type New bit *R
Used bit *R
Zaraby limestone T = 0.1228 WOB + 0.6537 0.99 T = 0.135 WOB – 0.0042 0.99
White Marble T= 0.1919 WOB -0.0352 0.99 T = 0.1882WOB - 0.0695 0.99
Pink Granite T = 0.2447 WOB +0.0133 0.99 T = 0.2392 WOB -0.0076 0.99
59
as the energy required for removing a unit volume of rock, or as the quantity of the
energy from a source expended through the bit to drill a volume of rock. It is a
variable of drilling process that is dependent on all the main drilling parameters:
weight on bit, rotational speed, penetration rate and the strength of rock. For example,
the specific energy serves to give an indication of the efficiency of the drilling process.
It is easily calculated for rotary drilling by means of the equation [4, 57, 58, 59, 68].
(4.2)
Where:
SE = Specific energy, Mpa
N = rotary speed, rpm
T = resistance torque, N.m
A = area of the bit, mm2
ROP= rate of penetration, m/hr
Figure 4.12 shows the relation between weight on bit (WOB) and specific
energy (SE) for Mankabad limestone at two different drilling speeds 300 and 1000
rpm. It obvious from this figure that the, specific energy decreases as weight on bit
increases until 60 kg WOB. So, this value is the best weight on bit (WOB) for drilling
this type of rock Figure 4.12. Figure 4.13 shows also, the relation between weight on
bit (WOB) and specific energy (SE) in Minia limestone. At WOB of 105 kg and 300
rpm the minimum value of specific energy was obtained. However, at 1000 rpm the
minimum value of specific energy was obtained at 90 kg WOB. Figure 4.14 introduces
the relation between weight on bit (WOB) and specific energy (SE) in Assiut
limestone at 300 and 1000 rpm. The minimum value of the specific energy is obtained
at 90 kg WOB.
60
Figure 4.12: Relation between weight on bit and specific energy at 300 and 1000 rpm
in Mankabad limestone
Figure 4.13: Relation between weight on bit and Specific energy at 300 and 1000 rpm
in Beni-Khalid, Samalout Limestone, Minia
0
100
200
300
400
500
600
700
0 20 40 60 80 100 120 140
Spec
ific
ener
gy (
SE
), M
pa
Weight on bit (WOB), kg
V1 =300 rpm (New bit)
V1=300 rpm (Used bit)
V2= 1000 rpm (New bit)
V2=1000 rpm (Used bit)
0
100
200
300
400
500
600
700
10 20 30 40 50 60 70 80
Sp
ecif
ic e
ner
gy (
SE
), M
pa
Weight on bit (WOB), kg
V1 =300 rpm (New bit)
V1=300 rpm (Used bit)
V2= 1000 rpm (New bit)
V2=1000 rpm (Used bit)
61
Figure 4.14: Relation between weight on bit and Specific energy at 300 and 1000 rpm
in Assiut cement company quarry Limestone, Assiut
Figure 4.15: Relation between weight on bit and Specific energy at 300 and 1000 rpm
in Issawyia Limestone, East Sohag
0
100
200
300
400
500
600
700
800
900
1000
0 20 40 60 80 100 120
Spec
ific
ener
gy (
SE
), M
pa
Weight on bit (WOB), Kg
V1 =300 rpm (New bit)
V1=300 rpm (Used bit)
V2= 1000 rpm (New bit)
V2=1000 rpm (Used bit)
0
200
400
600
800
1000
1200
0 20 40 60 80 100 120
Sp
ecif
ic e
ner
gy (
SE
), M
pa
Weight on bit (WOB), Kg
V1 =300 rpm (New bit)
V1=300 rpm (Used bit)
V2= 1000 rpm (New bit)
V2=1000 rpm (Used bit)
62
Figure 4.16: Relation between weight on bit and Specific energy at 300 and 1000 rpm
in Zaraby Limestone, Assiut
Figures 4.15 & 4.16 show that, at 90 kg WOB, 300, and 1000 rpm in Issawyia
and Zaraby Limestone, the minimum value of specific energy was obtained with both
new and used bits. So, this value is the best weight on bit (WOB) for drilling these two
types of rocks Figures 4.15 & 4.16.
By comparing all limestone rocks, results revealed that the minimum amount of
energy needed for drilling was for Mankabad limestone, and the maximum value of
consumed energy required during drilling was for Zaraby limestone, because Zaraby is
hardest one of all tested limestone. While, the minimum value of consumed energy
required during drilling was for Mankabad limestone, because Mankabad is the
weakest one of all tested limestone.
Zaraby limestone consumed (1.42, 2.08) and (1.45, 2.95) times of specific
energy for being drilled than Issawyia, and Assiut limestone at 90 kg WOB, 300 and
1000 rpm, respectively for both new and used bit. While, the specific energy needed in
Zaraby limestone is a (1.79-3.61) time that wanted for drilling Minia limestone at 300
and 1000 rpm for new and used bit at 105 kg WOB.
0
200
400
600
800
1000
1200
1400
1600
0 20 40 60 80 100 120
Sp
ecif
ic e
ner
gy (
SE
), M
pa
Weight on bit (WOB), Kg
V1 =300 rpm (New bit)
V1=300 rpm (Used bit)
V2= 1000 rpm (New bit)
V2=1000 rpm (Used bit)
63
Also the specific energy consumed for drilling Zaraby limestone is (2.08-3.76)
times that consumed during drilling Mankabad limestone at 60 kg. Figures 4.17& 4-18
show that the specific energy consumed for drilling black and white marble is higher
than that consumed in all limestone rocks at 300 and 1000 rpm and 90 kg weight on bit
(WOB).
Figure 4.17: Relation between weight on bit and Specific energy at 300 and 1000 rpm
in Black Marble, Wadi El-Miah, Eastern Desert
Figure 4.18: Relation between weight on bit and Specific energy at 300 and 1000 rpm
in White Marble, Wadi El-Miah, Eastern Desert
0
500
1000
1500
2000
2500
3000
0 20 40 60 80 100 120
Sp
ecif
ic e
ner
gy (
SE
), M
pa
Weight on bit (WOB), Kg
V1 =300 rpm (New bit)
V1=300 rpm (Used bit)
V2= 1000 rpm (New bit)
V2=1000 rpm (Used bit)
0
500
1000
1500
2000
2500
3000
20 40 60 80 100 120
Sp
ecif
ic e
ner
gy (
SE
), M
pa
Weight on bit (WOB), Kg
V1 =300 rpm (New bit)
V1=300 rpm (Used bit)
V2= 1000 rpm (New bit)
V2=1000 rpm (Used bit)
64
The specific energy consumed for black marble, at 90 kg, 300 and 1000 rpm is
(1.07-1.4) times that needed for drilling in white marble at the same values of WOB
and RPM. Also, the comparison between specific energy required for marbles and
limestone has shown that the specific energy for white marble was (1.5-2.2) times that
for Zaraby limestone which is the hardest limestone rock in our research.
Figures 4.19 & 4.20 for pink and black granites, illustrate that the specific
energy consumed in black granite at 210 kg and 300 and 1000 rpm for used and new
bit is (1.34-1.63) times that consumed in drilling pink granite.
Figure 4.19: Relation between weight on bit and Specific energy at 300 and 1000 rpm
in pink granite, Aswan
Bit condition has a great influence on the amount of specific energy consumed.
Using new bit at constant weight on bit of 90 kg WOB and rotary speed of 1000 rpm,
the specific energy consumed for drilling the black granites was 14.5, 29.6 times that
consumed in white marble and Zaraby limestone respectively. The amount of specific
energy was highly increased and became 25.42, 55.9 times that in white marble and
Zaraby limestone respectively.
0
5000
10000
15000
20000
25000
70 120 170 220 270
Spec
ific
ener
gy (
SE
), M
pa
Weight on bit (WOB), Kg
V1 =300 rpm (New bit)
V1=300 rpm (Used bit)
V2= 1000 rpm (New bit)
V2=1000 rpm (Used bit)
65
The effect of rotary drilling speed on specific energy consumption, increasing
drilling speed causes an increase in specific energy, especially with used bit. As
shown in figures (4-16, 4-18) for Zaraby limestone and white marble, as examples
when using new at 90 kg WOB and 1000 rpm, the required specific energy is 1.25,1.6
times that at 300 rpm respectively. At the same conditions, using used bit the required
specific energy is 1.34, 1.74 times that at 300 rpm respectively. At 210 kg WOB and
1000 rpm for black granite figure (4-20), the value of energy consumption is 1.67-1.9
times that at 300 rpm.
Figure 4.20: Relation between weight on bit and Specific energy at 300 and 1000 rpm
in black granite, Aswan
Tables 4.4 & 4.5 introduce the correlation equations of the relationships
between Specific energy (SE, Mpa) and weight on bit (WOB, Kg) for all tested rocks
at 300 rpm and 1000 rpm respectively.
0
50000
100000
150000
200000
250000
300000
0 100 200 300 400 500 600
Spec
ific
ener
gy (
SE
), M
pa
Weight on bit (WOB), Kg
V1 =300 rpm (New bit)
V1=300 rpm (Used bit)
V2= 1000 rpm (New bit)
V2=1000 rpm (Used bit)
66
Table 4.4: Correlation equations of the relationships between (SE) and (WOB) for all tested
rocks at 300 rpm
Rock
type
New bit
*R
Used bit *R
Mankabad
limestone
SE= 0.2404 WOB2 -17.063 WOB+358.36 0.92 SE= 0.195WOB
2 -13.762 WOB+373.72 0.92
Minia
limestone
SE= 0.0389 WOB2 -5.657 WOB +296.76 0.93 SE= 0.03 WOB
2 – 4.2285 WOB +335.7 0.69
Assiut
limestone
SE= 0.1273 WOB2 -14.401WOB +512.66 0.85 SE= 0.092 WOB
2 - 10.644 WOB +550.9 0.73
Issawyia
limestone
SE= 0.0752 WOB2 -9.2216WOB +463.51 0.86 SE= 0.0913 WOB
2 -10.841 WOB +573.82 0.74
Zaraby
limestone
SE= 0.1054 WOB2 -13.98 WOB +741.5 0.80 SE= 0.1534WOB
2 -17.244 WOB +687.66 0.79
white
marble
SE= 0.4514 WOB2 -61.07 WOB +2309 0.86 SE= 0.0999 WOB
2 – 3.1057 WOB
+219.29
0.88
black
marble
SE= 0.2853 WOB2 -38.156WOB +1749.5 0.90 SE= 0.3713 WOB
2 – 50.469 WOB
+2255.9
0.92
pink
granite
SE= 0.3094 WOB2 -119.36WOB+14190.06 0.98 SE= 0.6357WOB
2 – 200.12 WOB +20100 0.78
black
granite
SE= 0.0836 WOB2 -61.938WOB +14374 0.97 SE= 0.0744 WOB
2 -54.597 WOB +16103 0.88
Table 4.5: Correlation equations of the relationships between (SE) and (WOB) for all tested
rocks at 1000 rpm
Rock type New bit
*R
Used bit *R
Mankabad
limestone
SE= 0.2697 WOB2 -19.458 WOB +484.28 0.91 SE= 0.2034WOB
2 -14.816 WOB +565.34 0.91
Minia
limestone
SE= 0.0424 WOB2 – 5.7987 WOB +406.8 0.92 SE= 0.1115WOB
2 – 15.651 WOB
+840.91
0.93
Assiut
limestone
SE= 0.111 WOB2 – 13.877 WOB +801.82 0.82 SE= 0.2166 WOB
2 – 27.897 WOB
+1272.1
0.92
Issawyia
limestone
SE= 0.2101 WOB2 – 25.586 WOB +1043.5 0.88 SE= 0.2385 WOB
2 – 30.394 WOB
+1365.4
0.89
Zaraby
limestone
SE= 0.05224 WOB2 – 1.40 WOB +127.69 0.75 SE= 0.287 WOB
2 – 41.5 WOB +1859.1 0.91
White
Marble
SE= 0.6453 WOB2 -61.78 WOB + 1198.74 0.93 SE= 0.8499WOB
2 -123.09 WOB + 5256.8 0.91
Black
marble
SE= 0.3469WOB2 – 45.568 WOB +2218 0.78 SE= 0.7345WOB
2 – 105.73WOB +4955.1 0.85
Pink
Granite
SE= 0.6453 WOB2 – 207.17 WOB +21183 0.79 SE= 1.6414WOB
2 – 620.14 WOB - 65673 0.96
Black
granite
SE= 0.9413 WOB2 – 320.83WOB +35710 0.79 SE= 1.7685 WOB
2 – 683.18WOB +76589 0.94
*R: Correlation coefficient
67
The best drilling conditions for all tested rocks are given in Table 4.6. Also,
some of the predicted values of both rate of penetration (ROP) and Specific energy
(SE) are introduced in Tables 4.7 & 4.8 for some tested rocks.
Table 4.6: Best drilling conditions for all tested rocks
Rock
type
V1=300 RPM V2 =1000 RPM
New bit Used bit New bit Used bit
WOB,
Kg
ROP,
cm/min.
SE,
MPa
WOB,
Kg
ROP,
cm/min.
SE,
MPa
WOB,
Kg
ROP,
cm/min.
SE,
MPa
WOB,
Kg
ROP,
cm/min.
SE,
MPa
Mankabad
limestone 60 9.83 103.70 60 5.85 170.5 60 19.53 174 60 10.18 326
Minia
limestone 105 12.16 94.54 105 7.3
154.3
105 13.67 280.33 105 8.65 433.9
Assiut
limestone 90 9.53 118.10 90 5.21
211.6
90 11.25
333.6
90 9.3 362.3
Issawyia
limestone 90 6.6 167 90 4.87
221.5
90 13.32
275.8
90 9.68 371.4
Zaraby
limestone 90 4.22 348.2 90 3.67 392.4 90 11.26 435 90 9.13 525.7
white
marble 90 4 509.63 90 2.76 725.71 90 7.66 887.08 90 5.78 1155.1
black
marble 90 4.11 47869 90 3.56 542.7 90 10.33 634.9 90 6.86 937.3
pink
granite
210 2.09 2914.7 210 1.002 4802.31 210 3.14 5227.63 210 2.48
5467.51
black
granite
480 4.8 3004.8 480 2.63 5363 240 2.89 8311 240 2.4 9794
Table 4.7: Predicted values of drilling rate (ROP, cm/min.) at the best weight on bit (WOB) as
an example for tested rocks
Rock
Type
Best
Weight
on bit
(WOB),
Kg
V1=300 RPM V2 =1000 RPM
New bit Used bit New bit Used bit
Meas*.
Calc*.
%
Diff.
Meas*.
Calc*.
%
Diff.
Meas*.
Calc*.
%
Diff.
Mea*s.
Calc*.
%
Diff.
Zaraby
limestone
90 4.22 3.84 9 3.67 3.44 6.27 11.26 10.13 10.04 9.13 8.38 8.21
White
marble
90 4.00 3.77 5.75 2.76 2.44 11.59 7.66 6.87 10.31 5.78 5.45 5.71
Pink
granite
210
2.09 2.22 -6.2
1.002 0.95 5.19 3.14 3.00 4.46 2.48 2.30 7.26
68
Table 4.8: Predicted values of Specific energy (SE, Mpa) at the best weight on bit (WOB) as
an example for tested rocks
Rock
Type
Best
Weight
on bit
(WOB),
Kg
V1=300 RPM V2 =1000 RPM
New bit Used bit New bit Used bit
Meas*
.
Calc*.
%
Dif
f.
Meas*
.
Calc*.
%
Diff
.
Meas*
.
Calc*.
%
Diff.
Meas*.
Calc*.
%
Diff.
Zaraby
limeston
e
90
348.2
337.04
3.1
392.4
378.24
3.6
435
424.85
2.33
525.7
448.5
15
White
marble
90
509.63
469.40
7.89
725.71
749.74
-3.3
887.08
865.47
2.44
1155.1
1062.9
8
Pink
granite
210
2914.7
2769
5.0
5937.8
6109.2
-2.9
6466.8
6135.03
5.13
7996.6
7829.3
2.1
Meas*. : Measured value.
Calc*. : Calculated value.
4.4 Relationships between rate of penetration (ROP) and specific energy (SE) for all
tested rocks
Curve fitting was made to obtain the mathematical relationships between rate of
penetration (ROP) and specific energy (SE) for all types of tested rocks. Correlation
coefficients were given for all tested rocks. Figures (4.21 to 4.29) illustrate the
relationships between rate of penetration (ROP) and specific energy (SE) for
Mankabad, Minia, Assiut, Issawyia, and Zaraby limestone respectively, at both speeds
300, 1000 rpm using new and used bits. It can be seen that specific energy (SE) is
inversely proportional with the rate of penetration (ROP) in all tested rocks. But
Mankabad limestone requires the least amount of specific energy compared with other
types of tested limestone, while, Zaraby limestone requires the highest amount of
specific energy compared with other tested types of limestone rocks. The lower value
of specific energy indicates that the bit is drilling more efficiently. For granites, at
WOB of 210 kg and drilling speed of 1000 rpm the specific energy consumed is 1.5,
1.9 times which consumed at 210 kg and 300 rpm. For Limestone and Marbles, at
constant weight on bit of 90 kg and drilling speed of 1000 rpm, the specific energy
consumed is 1.25, 1.34 and 1.59, 1.74 times that consumed at 300 rpm respectively.
69
Figure 4.21: Relation between rate of penetration and Specific energy at 300 and 1000
rpm in Mankabad Limestone, Assiut
Figure 4.22: Relation between rate of penetration and Specific energy at 300 and 1000
rpm in Beni-Khalid, Samalout Limestone, Minia
50
100
150
200
250
300
350
400
0 5 10 15 20 25
Sp
ecif
ic e
ner
gy (
SE
), M
pa
Rate Of Penetration (ROP), cm/min.
V1=300 rpm (New bit)
V1= 300 rpm (Used bit)
V2 =1000 rpm (New bit)
V2= 1000 rpm (Used bit)
0
100
200
300
400
500
600
700
0 5 10 15 20
Sp
ecif
ic e
ner
gy (
SE
), M
pa
Rate of penetration (ROP), cm/min.
V1=300 rpm (New bit)
V1= 300 rpm (Used bit)
V2 =1000 rpm (New bit)
V2= 1000 rpm (Used bit)
70
Figure 4.23: Relation between rate of penetration and Specific energy at 300 and 1000
rpm in Assiut cement company quarry Limestone, Assiut
Figure 4.24: Relation between rate of penetration and Specific energy at 300 and 1000
rpm in Issawyia Limestone, East Sohag
100
200
300
400
500
600
700
800
900
1000
0 2 4 6 8 10 12 14
Sp
ecif
ic e
ner
gy (
SE
), M
pa
Rate of penetration (ROP), cm/min.
V1=300 rpm (New bit)
V1= 300 rpm (Used bit)
V2 =1000 rpm (New bit)
V2= 1000 rpm (Used bit)
0
100
200
300
400
500
600
700
800
900
1000
0 2 4 6 8 10 12
Sp
ecif
ic e
ner
gy (
SE
), M
pa
Rate of penetration (ROP), cm/min.
V1=300 rpm (New bit)
V1= 300 rpm (Used bit)
V2 =1000 rpm (New bit)
V2= 1000 rpm (Used bit)
71
Figure 4.25: Relation between rate of penetration and Specific energy at 300 and 1000
rpm in Zaraby Limestone, Assiut
Figure 4.26: Relation between rate of penetration and Specific energy at 300 and 1000
rpm in Black Marble, Wadi-El-Miah, Eastern Desert
200
400
600
800
1000
1200
1400
0 2 4 6 8 10 12
Sp
ecif
ic e
ner
gy (
SE
), M
pa
Rate of penetration (ROP), cm/min.
V1=300 rpm (New bit)
V1= 300 rpm (Used bit)
V2 =1000 rpm (New bit)
V2= 1000 rpm (Used bit)
200
600
1000
1400
1800
2200
0 2 4 6 8 10 12
Spec
ific
en
ergy (
SE
), M
pa
Rate of penetration (ROP), cm/min.
V1=300 rpm (New bit)
V1= 300 rpm (Used bit)
V2 =1000 rpm (New bit)
V2= 1000 rpm (Used bit)
72
Figure 4.27: Relation between rate of penetration and Specific energy at 300 and 1000
rpm in White Marble, Wadi-El-Miah, Eastern Desert
Figure 4.28: Relation between rate of penetration and Specific energy at 300 and 1000
rpm in Pink Granite, Aswan
0
500
1000
1500
2000
2500
3000
0 2 4 6 8 10
Sp
ecif
ic e
ner
gy (
SE
), M
pa
Rate of penetration (ROP), cm/min.
V1=300 rpm (New bit)
V1= 300 rpm (Used bit)
V2 =1000 rpm (New bit)
V2= 1000 rpm (Used bit)
0
2000
4000
6000
8000
10000
12000
14000
16000
0 0.5 1 1.5 2 2.5 3 3.5
Spec
ific
ener
gy (
SE
), M
pa
Rate of penetration (ROP), cm/min.
V1=300 rpm (New bit)
V1= 300 rpm (Used bit)
V2 =1000 rpm (New bit)
V2= 1000 rpm (Used bit)
73
Figure 4.29: Relation between rate of penetration and Specific energy at 300 and 1000
rpm in Black Granite, Aswan
Table 4.9: Correlation equations of the relationship between (SE) and (ROP) for tested rocks
at 300 rpm
Rock
type
New bit
*R
Used bit *R
Mankabad
limestone
SE= 0.1192 ROP2 -4.0862 ROP +132.31 0.99 SE= 0.0652ROP
2 -3.5775 ROP
+189.57
0.98
Minia
limestone
SE= 1.5107 ROP2 – 28.49 ROP +224.49 0.97 SE= 0.8556ROP
2 – 22.035
ROP+270.78
0.99
Assiut
limestone
SE= 3.0766 ROP2 – 48.079 ROP +305.43 0.96 SE= 3.4729 ROP
2 – 53.409 ROP
+394.45
0.99
Issawyia
limestone
SE= 4.752 ROP2 – 57.386 ROP +345.35 0.98 SE= 5.2049 ROP
2 – 66.433 ROP
+418.97
0.99
Zaraby
limestone
SE= 10.882 ROP2 – 100.24 ROP +577.67 0.99 SE= 14.39 ROP
2 – 120.8 ROP +
643.9
0.99
white
marble
SE= 51.972 ROP2 -391.03 ROP + 1245.9 0.99 SE= 89.966ROP
2 -486.99 ROP +
1395
0.99
black
marble
SE= 39.263ROP2 – 289.85 ROP +1016.3 0.99 SE= 74.874 ROP
2 – 467.67 ROP +
1273.6
0.99
pink
granite
SE= 1104 ROP2 – 4367.8 ROP + 6719.7 0.99 SE= 753.88 ROP
2 – 4000.9 ROP –
8017.9
0.99
black
granite
SE= 432.52 ROP2 – 3306.7 ROP + 9138.4 0.97 SE= 863.33 ROP
2 – 4564.7 ROP +
11495
0.99
0
5000
10000
15000
20000
25000
30000
0 1 2 3 4 5 6
Sp
ecif
ic e
ner
gy (
SE
), M
pa
Rate of prnetration (ROP), cm/min.
V1=300 rpm (New bit)
V1= 300 rpm (Used bit)
V2 =1000 rpm (New bit)
V2= 1000 rpm (Used bit)
74
Table 4.10: Correlation equations of the relationship between (SE) and (ROP) for tested
rocks at 1000 rpm
Rock
type
New bit
*R
Used bit *R
Mankabad
limestone
SE= -0.0294 ROP2 – 1.954 ROP +
223.87
0.99 SE= -0.2178 ROP2 – 3.5567 ROP +
370.64
0.99
Minia
limestone
SE= 0.7637 ROP2 – 21.606 ROP +355.32 0.96 SE= 0.6.3371ROP
2 –
106.95ROP+732.62
0.90
Assiut
limestone
SE= 2.1194 ROP2 – 49.368 ROP +624.91 0.99 SE= 8.7614 ROP
2 – 142.18 ROP
+931.89
0.95
Issawyia
limestone
SE= 3.9167 ROP2 – 83.801 ROP +711.86 0.99 SE= 9.7388 ROP
2 – 153.77 ROP
+974.56
0.95
Zaraby
limestone
SE= 2.5934 ROP2 – 70.953 ROP +914.07 0.97 SE= 14.527 ROP
2 – 222.28 ROP
+1373.7
0.97
white
marble
SE= 20.997 ROP2 -297.4 ROP + 1942.1 0.99 SE= 79.827 ROP
2 -821.77 ROP +
3268.4
0.99
black
marble
SE= 2.759ROP2 – 85.812 ROP +1228.5 0.99 SE= 42.746 ROP
2 – 552.22 ROP
+2729.5
0.99
pink
granite
SE= 183.14 ROP2 – 1851.7 ROP + 9263 0.99 SE= 2618.2 ROP
2 – 11917 ROP -
19958
0.99
black
granite
SE= 655.48 ROP2 – 4415.5 ROP + 15608
0.99
SE= 6194.9 ROP2 – 24716 ROP +
34295
0.97
*R: Correlation coefficient
It is clear that the three categories of rocks, Zaraby limestone, White marble
and Black granite are the hardest formations in all tested rocks. As an example, to
obtain the rate of penetration of 2 cm/min. at 300 and 1000 rpm using new and used
bit, Black granite requires an amount of specific energy 9.52, 13.64 and 6.15, 7.5 times
that for Zaraby limestone and White marble respectively.
4.5 Identifying the rock type to be drilled using drilling parameters
In this section a study to calculate the specific energy consumed during the
drilling tests for all tested rocks, and comparing these energies for each rock type is
carried out. Thereafter, a new index (UCS/SE) as a ratio between uniaxial compressive
strength of rock and specific energy of drilling machine is calculated for all tested
rocks at different loads and different rotary speeds. Relationships between UCS/SE
and rate of penetration (ROP) which are previously calculated by using different
weights on bit and rotational speeds, for sedimentary (limestone), metamorphic
(marbles), and igneous (granites) were plotted.
75
Specific energy (SE) is calculated for all types of rocks by using the following
equation [69, 70, 71]:
(4.3)
Where:
W= Weight on bit, (kg)
N=Revolution per min.
D= Diameter of bit (mm), and
= Penetration rate ( ⁄ ).
SEV = Specific energy,
⁄
Note that, the quantity SEV has the same dimensions as the stress and that a
convenient unit for specific energy is the Mpa (an equivalent unit for specific energy is
the ( ⁄ ) which is numerically identical to MPa) [5].
The study will concentrate on the calculation of the specific energies consumed
during drilling tests for all tested rocks and comparing these energies for each rock
type. Thereafter, a new index UCS/SE is calculated for all tested rocks at different
loads and rotary speeds. Relationships between the rate of penetration and specific
energy for all rocks are determined to give a comparison between the consumption of
energy in three types of rock being drilled. Relationships between UCS/SE and the rate
of penetration (ROP) are also derived for sedimentary (limestone), metamorphic
(marbles) and igneous rocks (granites).
4.5.1 I -Variation of specific energy with the rock types
Values of drilling rate and specific energy for limestone, marbles and granites
have been averaged and one value for each applied rotary speed represents each rock
group. Each average value of drilling rate and specific energy was determined as an
arithmetic mean for the values of each rock group related to nominal speed. Tables (3-
76
14) and (3-15) of chapter (3) above give the average values of the specific energy and
UCS/SE for limestone, marbles and granites at 1000 and 300 rpm and different loads
for the new bit respectively.
Curve fitting was made for the average values of drilling rate to obtain
empirical equations representing the relationship between specific energy (SE) and
Rate of penetration (ROP) of different rocks[72, 73, 74]. Both experimental and
fitting values of the rate of penetration (ROP) were plotted against the specific energy
(SE) for all rocks at the applied different loads on bit (WOB) as shown in figures (4-
30) and (4-31). The most suitable mathematical equations to fit the data were given
and written, related to each curve in the figures. Figures (4-30, 4-31) show that the
specific energy for all tested rocks at 1000 and 300 rpm and under different loads for
the new bit decreases with the increase of drilling rate. As the thrust load increases,
the work lost in friction will constitute a rapid decrease in the total work done. This
effect will contribute to a fall in specific energy. However, this fall will not continue
indefinitely, a stage may be reached when the tool is pushed so heavily into the rock
that it becomes overloaded and clogs.
The figures generally show the specific energy for all rocks decreased with
increased drilling rate. Comparing the plotted data on Figures 4.28 & 4.29, it can be
seen that as the drilling rate was increased, the magnitude of the change in specific
energy was not the same for limestone, marble and granite. Then, the igneous rock
types had lower drilling rates and higher specific energy than the metamorphic and
sedimentary rock types under investigation.
From Tables 3.14 & 3.15 for different rocks at 1000 and 300 rpm and at
different loads, the marbles needed an amount of specific energy from 2.7, 3.55 times
that of limestone. The granite rocks needed specific energy from 13.19, 14.80 times
that of marbles, and from 36.17, 51.26 times that of limestone needed to complete this
operation at 90kg WOB.
77
Figure 4.30: Relationship between average rate of penetration and specific energy for
all rocks at different loads and drilling speed of 1000 rpm
Figure 4.31: Relationship between average rate of penetration and specific energy for
all rocks at different loads and drilling speed of 300 rpm
0
2000
4000
6000
8000
10000
12000
0 20 40 60 80 100 120 140
Rate of penetration (ROP, mm/min.)
Sp
ecif
ic e
nerg
y (
SE
, M
Pa)
Limestone
Fitting
Marble
Fitting
Granite
Fitting
SE=-1.8324 ROP + 532.68
SE=0.1003 ROP^2 - 18.242 ROP +1596.5
SE=21709 ROP ^ -0.3088
SE = -2.1508 ROP + 301.72
SE = 10153 (ROP)-0.3218
0
1000
2000
3000
4000
5000
6000
7000
0 20 40 60 80 100
Rate of penetration (ROP, mm/min.)
Sp
ec
ific
en
erg
y (
SE
, M
Pa
)
Limestone
Fitting
Marble
Fitting
Granite
Fitting
SE = -12.398 ROP + 42.91
78
4.5.2 II- Relation between UCS/SE and ROP
On the other hand, specific energy and the dimensionless index UCS/SE were
determined for the three types of rocks at the applied rotary speeds 300 and 1000 rpm
and at different loads as given before in Tables 3.11 to 3.13. The results of
calculations at applied rotary speeds 300 and 1000 rpm and at different loads for new
bit are obtained. The rate of penetration is plotted against the dimensionless index
UCS/SE for all rocks as shown in Figures 4.32 & 4.33. About 48 points are plotted
together representing the sedimentary, metamorphic and igneous rocks from which, 28
points represent 5 limestone at six different loads and two different rotary speeds, 10
points represent marbles (2 types) at five different loads and two different rotary
speeds, and 10 points represent granites(2 types, one of them at eight different loads
and 300 rpm and the other at five different loads and 1000 rpm). It can be seen that
there is no distinct areas for the three types of rocks.
Figure 4.32: Relationship between UCS/SE and Rate of penetration for all rocks at
different loads and rotary speed of 1000 rpm, new bit
0
20
40
60
80
100
120
0 20 40 60 80 100 120
Rat
e o
f pen
etra
tion (
RO
P),
mm
/min
.
Index ((UCS/SE)*10^-3
Limestone
Marble
Granite
79
Figure 4.33: Relationship between UCS/SE and Rate of penetration for all rocks at
different loads and rotary speed of 300 rpm, new bit
Increasing the rotary speed from 300 to 1000 rpm will increase the penetration
rate by high values in case of limestones but it is not the same in case of marbles and
granites as mentioned before. Then , excluding again the values of rate of penetration
(ROP) against the dimensionless index (UCS/SE) at the same loads but at rotary
speed 300 rpm to see if the three rocks are to fall into distinct zones. Figure (4-34)
represents the results at loads 45, 60, 75, 90, 120, 150, 180, 210, 300, 390 and 480 kg
and at rotary speeds 300 rpm for the new bit.
In Figure 4.34, it is clear that there are only two distinct zones one for
limestones alone and the other for both marbles and granites. It can be concluded that
at higher rotary speed and lower loads for drilling the three types of rocks
(representing sedimentary, metamorphic and igneous) are lying in three distinct zones.
At higher loads and lower rotary speed there are only two distinct zones one for
seimentary and the other for metamorphic and igneous together. Increasing the
0
50
100
150
200
0 10 20 30 40 50 60 70
Rat
e o
f p
enet
rati
on (
RO
P),
mm
/min
.
Index (UCS/SE)*10^-3
Limestone
Marble
Granite
80
mechanical energy level on a bit (or increasing thrust load and rotary speed) will
increase the penetration rate if there is a sufficient hydraulic energy available for
bottom hole cleaning. Increasing thrust load and rotary speed, however, accelerate bit
cutting and wear. In soft formations a doubling of either load or rotary speed will
double penetration rate if sufficient horsepower is available. In hard formations the
load has to be sufficient to overcome the compressive strength of the rock, then
increasing the load on bit by a factor of two doubles or more doubles the penetration
rate.
The penetration rate is not linearly proportional to rotary speed in drilling hard
formations because some finite time is required for a bit to fracture the rock .
Accordingly, as can be seen from Figure 4.32 & 4.33 increasing loads on bit increases
penetration rate by high values in limestones and does not increase it for marbles and
granites by the same values. Also Figures 4.32 & 4.33 show that, at both rotary
speeds 1000 and 300 rpm for all applied loads respectively, the values of the rate of
penetration (ROP) were plotted against dimensionless index (UCS/SE) for all rocks.
The values related to rock types are close to each other. Accordingly, there is no
distinct areas for each rock type. If we exclude the rates of penetration that
correspond to the lower loads 15 and 30 kg using lower speed (300 rpm), it would be
seen that the three groups of rocks are lying only into two distinct areas, one for
sedimentary and the other for both metamorphic and igneous rocks together as shown
in Fig. 4.34.
81
Figure 4.34: Relationship between UCS/SE and rate of penetration for all rocks at
rotary drilling of 300 rpm and loads of 45, 60, 75, 90, 120, 150, 180, 210,
300, 390 and 480 kg, new bit
Figure 4.35: Relationship between UCS/SE and rate of penetration for all rocks at
rotary drilling of 1000 rpm and loads of 45, 60, 75, 90, 120, 150, 180,
210, 300, 390 and 480 kg, new bit
0
20
40
60
80
100
120
0 20 40 60 80 100 120
Ra
te o
f p
en
etr
ati
on
(R
OP
),
mm
/min
.
Limestone
Marble
Granite
Index UCS/SE X 10^-3
Limestone
Marble + Granite
0
50
100
150
200
250
0 10 20 30 40 50 60 70
Rate
of
pe
netr
ati
on
(R
OP
), m
m /
min
.
Limestone
Marble
Granite
Index UCS/ES X 10^-3
82
CHAPTER 5
5 CONCLUSIONS AND RECOMMENDATIONS
Drilling trials are conducted on three types of rocks, sedimentary rocks namely,
Mankabad, Assiut cement company quarry, and Zaraby limestone, Assiut. Issawyia
limestone, East Sohag and Beni-Khalid, Samalout limestones, Minia. Metamorphic
rocks namely, white and black marbles, from Wadi El-Miah, Eastern Desert, and
igneous rocks namely, pink and black granites from Aswan. By using a stationary
laboratory- drilling machine over a range of weights on bit. (WOB = 15, 30, 45, 60,
75, 90, 105 and 105 kg) for sedimentary tested rocks (limestones) and (WOB = 30, 45,
60, 75 and 90 kg) for metamorphic tested rocks (marbles), and the loads on bit for
granites (WOB= 90, 120, 150, 180, 210, 240, 300, 390, 480 and 570 kg). All tests
were carried out at 300 and 1000 rpm using new and used bit.
Physical properties (density and porosity) and mechanical properties (compressive
strength, tensile strength, shear strength, and coefficient of internal friction) were
measured to give a complete description about the tested rocks as given in Table 3.1.
Relationships between both weight on bit, rate of penetration, specific energy, and
torque. Rate of penetration and specific energy were given, Figs. 4.1 to 4.29.
Relationships between WOB and both ROP and SE were determined. The results for
ROP are high correlated with the operating parameters. Rate of penetration increases
rapidly in Zaraby limestone (hardest type of all tested limestone) with increasing
weight on bit. Maximum value of penetration rate and minimum value of energy
consumption was obtained at weight on bit of 90 kg WOB, so this value is considered
the best weight on bit. The highest value of the rate of penetration ROP was obtained
during drilling limestones by using small weight on bit and high drilling speeds, while
it can be obtained by using heavy weights on bit and small drilling speeds in Marbles
and Granites. So that, it is recommended to use small WOB and high speeds with
weak rocks and vice versa with hard rocks.
83
The effect of bit condition upon the drilling parameters, for example, in Zaraby
limestone when using a new bit for drilling the rate of penetration (ROP) is 1.15 – 1.23
times that of used one. For white marble, the rate of penetration when using a new bit
is 1.45 – 1.33 times that of used bit. Also for pink granite introduces that the rate of
penetration (ROP) with new bit is 2-1.27 times that of used one. From the economic
point of view, the rate of penetration (ROP) in the weak rocks is less influenced when
using new and used bits than with hardest rocks, so that, it is recommended to use bits
for longer periods of time to drill weak rocks, in comparison with hard rocks, where
the time periods are to be shorter. For the three types of rocks, the best drilling
conditions were summarized in Table 4.21. The results have revealed that, the best
weight on bit (WOB) is that gives maximum rate of penetration (ROP) and minimum
amount of specific energy consumption (SE).
The specific energy for drilling in different categories of rocks were obtained by
using diamond core drilling. It is noticed that the specific energy (SE) decreases by
increasing weight on bit (WOB) until a certain limit and then it is either constant or
begins to increase. The lower values of specific energy (SE) indicate that the bit is
drilling more efficiently in limestones than the other two rocks. To achieve low values
of specific energy (SE), it is obviously advantageous to have rate of penetration as a
high as possible. The variation in specific energy for all rocks at applying different
loads and different rotary speeds were discussed. It is found that the marbles needed
amount of specific energy from 2.7-3.55 times that of limestones. The granite rocks
needed specific energy from 13.19-14.8 times that of marbles, and from 36.17-51.26
times that of limestones needed, according to applied loads, to complete this operation.
Relationships between rate of penetration (ROP) and specific energy (SE) for all
types of rocks at different loads and different rotary speeds were obtained and plotted
in Figures 4.30 & 4.31. The dimensionless index (UCS/SE) is calculated and given in
Tables 3.11 to 3.13. The relationships between the rate of penetration (ROP) and
(UCS/SE) were plotted at different thrust loads and different rotary speeds as shown in
Figures 4.32 to 4.35. Determining the new index (UCS/SE), we can specify the rock
84
type and its penetration rate. The following Table 5.1 gives the range of drilling
parameters values related to the three types of rocks.
Table 5.1: The range of drilling parameters values related to the three types of rocks
Type
Of
Rock
WOB,
Kg
T,
N.m
ROP,
Cm/min
SE,
MPa
(UCS/SE)*10-3
300
RPM
1000
RPM
300
RPM
1000
RPM
300
RPM
1000
RPM
Limestone
From
To
15
90
2.1
12.4
0.47
4.22
0.93
11.26
529.5
348.2
892
435
49
77.69
24.84
62.18
Marbles
From
To
]30
90
5.5
17.21
0.79
4
2.02
7.66
825.13
509.63
1077.4
887.08
49.14
100.7
37.6
57.9
Granites
From
To
90
480
22
119
0.4
4.8
0.9
-
6518.3
3004.8
9656.8
-
11.5
31.7
7.75
-
The results indicated that at all applied loads and two drilling rotary speeds (300
and 1000 rpm) there is no distinct zones. Whereas, at higher applied loads and lower
rotary speeds (300 rpm) the three groups of rocks are lying into two zones only: one
for sedimentary and the other for metamorphic and igneous. But, at higher applied
loads and higher rotary speeds (1000 rpm) the three groups of rocks are lying in three
distinct zones. In addition to other information obtained from the analysis of drill
cuttings, it can be possible to identify the actual rock type to be drilled. Future
researches related to drilling parameters as a tool of rock characterization which is
subject of this thesis may be recommended, namely: to discuss the use of different
rotary speeds other than 300 and 1000 rpm with different loads, and also to discuss the
drilling behavior related to other types of rocks.
85
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