109515084 7 linner cementing

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7” Liner - Cementing Preparation and Procedure Checklist

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(1 vote, average 4.00 out of 5)

This article is an example of a checklist for cementing a 7" liner.

• Hold pre-job planning meeting. All equipment to be checked and personnel familiar with the pl

• The final cement programme to be issued to the rig and approved by the Drilling Superintenden

• Ensure that BJ needs to blow out water from the lines after performing pressure test to avoid fro

in cold weather.

• Before cement job begins, ensure that the cement is fluffed and transferred from one tank to anotransfer in the cold weather.

• Prior to start cementing, ensure to perform the following:

o Total required volume of technical water to be stored on the rig site some days in advan

o Pre-job analysis of technical water, slurry and spacers. Perfrom tests for possible fluid c

program.

o Be sure the slurry formules is fit to avoid flash setting due to possible slurry dehydration

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Prepare cement mix water in the batch mixers and store in the KPO tanks, prepare spacers in th• Confirm that the Technical water is being supplied directly from the LMP. Do not use water fro

supervisor to check the water.

• Avoid using NaCL Brine to perfrom BJ lines test until a contamination test has been performed

• Ensure correct tanks and drill water are delivered at least 24 hours in advance of the cementing

• Check that cement chemicals have been added to the mix water in the correct order.

• Thoroughly mix each chemical after adding them to the mix water. Take samples of final mix f

verification tests.

• Ensure all BJ washer and spacers should be prepared in the batch mixer and pumped by the Cemcontrol avoid preparing washer and spacer in rig pits and avoid using rig pumps.

• Take 5 gallons dry cement sample in advance of the cement job so that pilot testing at cementin

carried out.

• Take 1 gallon mix water sample during the cement job.

• Check that the following equipment is available at the rig site: Weatherford circulating tool; LoDrilling Contractor?).

• Mud Logger to ensure stroke counters set to zero before pumping spacer and displacement.

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• While preparing the slurry, continue to circulate and check the following:

o Cement head bearing is secured to the derrick prior to rotating the liner

o The tugger must be manned at all times during rotation.

o There is a minimum of 20 Klbs (10 tonne) of drillpipe weight onto the liner prior to rota

of ‘HRD’ tool in ‘HRD’ profile of ‘ZXP’ packer to allow rotation of liner.o Establish circulation and rotation (generally ensure continued circulation during all rota

monitor rates and pressures.

o Note torque readings at 20 and 30 RPM with a minimum weight of 20 Klbs (10 Tonne)

o Check that the top drive is set properly in order not to limit the torque below programm

cementing job.

o Make sure there is good communication possible between the rig-floor and the cement u

location.

• Ensure that TDS IBOP is closed before hooking up the cement lines. Open the low torque valv

• If losses encountered during drilling 8 ½” hole section, attempt to cure losses before mixing and• If possible use the caliper log to calculate the slurry volume required.

o The Liner should be set 100m inside the 9 7/8" casing. Reduce the slurry top to 50 - 100

excess and TOC should be agreed & communicated to the team once the logs are run.

o Before the job check & calibrate all saipar and WFD-Datalog sensors and stroke counte

• Pump the required amount of cement as per cementing programme, allowing for volume of app

Top (with the DP connected to the hanger). Observe and note the torque required to rotate the

• Stop rotation to allow safe release of the Drill Pipe Pump Down Plug as follows (it is not allow

whilst rotating).

• When cementing the 7'' liner after bumping the plug to pressure up to 1000psi over final displac

mins.

Responsibilities during cementing

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(4 votes, average 4.50 out of 5)

Planning and supervision is crucial in cementing operations. This article describes the key responsibilit

Cementing Engineer, Mud Engineer and Drilling Contractor.

Operations Engineer

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• ensure cement, mixwater and additive samples are sent in time to the service company for testin

• check that the cementation proposal meets the objectives of planned cementing operation

• ensure cement, additive and mixwater samples are despatched correctly marked and packaged

• check log downhole temperature and compare with slurry design temperature.

• witness and check quality control of calliper logs

• check cementation proposal and reports

• discuss with cementing contractor about new equipment/chemicals

Drilling Supervisor

• overall responsibility for the conduct of the cementation

• compare job calculations with those of the Cementer

• supervise the Cementers and Drilling Contractor in the performance of their duties

• inform the Mud Loggers, Mud Engineer and Driller:

1. of the volume of each type of mixwater to be used for both lead and tail cement

2. from which mud pit each type of mixwater will be drawn

3. of the expected gain, per barrel of mixwater blended with cement, for both lead

4. of the expected total volume of returns during the cement job and the expected o

• co-ordinate the execution of the cement job

• ensure that all relevant personnel are issued with a detailed programme of the cement job, highl

(the detailed programme must include volumes, pressures and pump rates for the cementing and

• ensure that all relevant personnel are issued with contingency plans (flowcharts) to assist in rap

something go wrong

• witness:

1. no changes are made to the agreed programme without the prior approval of the

2. the landing and hanging off of the casing, including the pressure testing of hang

3. pressure testing of the surface lines before the job

4. the circulation test

5. the placing of the cement plugs in the cementing head6. the preparation of the cement slurry and spacers (no deviation from the recipe sh

7. the pumping of spacers and cement slurry

• count the number of tanks and fractions of tanks for the calculation of the volume of slurry pum

• use chart recorders during cementation to record as many relevant parameters as possible, such



1. pumping pressures

2. times of the various actions

3. cement slurry gradients

4. losses

• ensure equipment is in a state of readiness

• collect samples of mixwater, cement and additives during the cement job

• confirm stock levels of cement and additives

• supervise preparation of spacers, mixwater cement slurries and additives.

• ensure dry cement is fluffed as per Contractor recommended procedure

• prepare all cementation reports.

• complete checklists prior to commencement of cement job

• arrange loading and backloading equipment

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confirm receipt of the cement test report recipe for the cement and spacer from the Operations E• ensure that all checks are performed.

• Two days before the cementation is started, he will collect the checklists and address any problecarry out the checks, sign off the checklists and return them. A copy of the checklists shall be fa

Drilling Contractor

• operate and maintain the bulk air supply and mixing systems

• provide personnel for loading and backloading of supplies and equipment

• assist with sampling prior to, and during, the cement job• assist with measuring the gradient of the slurries pumped

• complete the minimum checks and procedures detailed in the checklists and pass completed che

prior to commencement of the cement job

• provide lines for cement and water from supply boat

• hook up cement/water lines as needed

Cementer

• maintain and operate the cement unit and all associated equipment on the rig to the highest stan

• ensure that the unit is functioning efficiently and has valid certification

• record and maintain quality control of stock levels of cement/additives and physically check all

prior to any cementing operation

• ensure that:

1. liquid additives are checked by use of a hydrometer



2. adequate spare parts and consumables to support the operation are maintained

3. all materials used and delivered are recorded in a log book

• carry out individual cement calculations and compare these with the calculations of the Drilling

• perform the cement job as per the programme specified by the company, including the use of d

• complete the minimum checks and procedures detailed in the checklists and pass completed che

prior to commencement of the cement job

• advise drilling supervisor of any changes in cementing program

• send the test results to the Operations Engineer and the Drilling Supervisor for verification at lescheduled.

• confirm the laboratory bench tests at the well site.

• distribute the checklists, which clearly define the responsibilities of personnel involved in the e

Mud Engineer• check the mixwater for contamination and measure salinity

• ensure mud is in good condition (no foam)

• ensure the mud has been pre-treated to minimise cement contamination problems

• ensure that there is sufficient volume of mud available on surface prior to commencement of th

• ensure sufficient space is available for spacer or additives to be stored

• monitor pit volumes throughout the cementation

• measure cement gradient as required

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check fluid returns for presence of cement, spacer or drilling fluid.

Mud Loggers

• monitor pit volumes throughout the cementation, independently of the Mud Engineer

• report to Drilling Supervisor immediately in case of discrepancies during displacement.

Last Updated on Friday, 10 June 2011 20:10Copyright © 2011 wipertrip.com. All Rights Reserved.

Cement Programme Preparation

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(4 votes, average 4.25 out of 5)The Cement Programme gives a brief explanation as to the objectives in setting casing, i.e.:

• isolate hydrocarbons• isolate different pressure regimes

• provide a pressure conduit of full integrity for drilling and completion

• allow installation of BOP, completion etc.

General Preparation Guidelines

The following guidelines should be applied to the preparation of the Cement Programme:

• The Drilling Supervisor shall prepare a call out fax seven days before the job.• The Cement Programme shall be sent to the Drilling Superintendent and Operations Engineer fo

• The final version of the Cement Programme, including the final details, shall be sent to the Dril

Operations Engineer.

• No last minute changes to the Programme shall be made without the prior approval of the Drilli

• A copy of the Programme shall be distributed to all rig personnel involved in the operation.

General responsibilities (execution and QA/QC) fo

Activity Execution Quality Control

Prepare the detailed

Cement Programme

Cementing Contractor Operations Engineer

Dispatch samples to

laboratory

Cementing Contractor Logistics / Materials

Supervisor

Test samples and preparerecipe

Cementing Contractor Operations Engineer

Verify Cement

Programme complies

with planned cementoperations

Operations Engineer Drilling Superintendent

Prepare well for

cementing

Drilling Contractor Drilling Supervisor

Mix, pump and displace

cement

Cementing Contractor Drilling Supervisor

Operations Engineer



Conduct rig floor

operations

Drilling Contractor Drilling Supervisor Tool

Pusher

Prepare Job Report Cement Contractor

Drilling Supervisor

Drilling Supervisor

Operations Engineer

Programme Design Consideration

The design considerations given in the following table should be taken into account when preparing the

Activity Design Consideration

Check shoe track andaccessory configuration.

-

Run and land casing as

per programmed casing

tally.

Proposed circulation test rates with corresponding

annular velocities (assuming gauge hole).

Pressure test surface

lines.

-

Mud Engineer checks all

tank levels.

When possible, mud returns shall be diverted to a

different pit to that used for suction during

displacement.

Mud Logger To adjust chart to monitor volume pumped and

volume returned.

Batch mix cement If feasible

Pump spacers ahead. Calculate volume, fluid type, gradient, fluid loss

Drop first plug ahead of

spacers.

-

Pump scavenger slurry. Calculate volume, gradient, cement sx., mixwater

volume

Drop bottom plug. -

Pump lead slurry. Calculate volume, gradient, fluid loss, cement type,

cement sx., mixwater volume, recipe, excess(referred to basis of calculation).

Pump tail slurry. Calculate volume gradient, cement type, cement sx.,

mixwater volume, recipe, excess (referred to basis

of calculation).

Drop top plug. -

Pump spacer behind Calculate volume, fluid type, gradient, over/under balance



Mud engineer checks all

tank levels.

-

Displace cement. • Calculate volume, fluid type, gradient, rate

before and after catch up.

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Calculate volume of mud pumped whencement starts to flow into annulus (pressure

increase)

• Total volume pumped when rate must bereduced for bump.

• Total volume pumped at bump.

• Bump pressure (casing pressure test) and

duration.

• Pump efficiency.

• Maximum permissible “over displacement”

past theoretical value to avoid physical over displacement of the slurry.

• Annular velocity.

• Flow regime of spacers and slurry.

• Contact time for any critical point in the

wellbore - eg., across a particular gas sand.

Mud Engineer checks all

tank levels.

-

Bleed off, check

backflow.

Proposed course of action if backflow is observed.

Cut / Back out landing

joint.

-

Cement Testing - QA/QC

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All slurry and spacers are designed and tested at the Cementing Contractors Laboratory. Samples of cem

mixwater must be sent from the well site to the laboratory for this purpose. Testing is carried out accord

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General Guidelines

• Bulk cement shall be sampled for testing purposes.

• After retaining a portion for bench testing, the remainder shall be despatched to the Contractor,

• The Laboratory test results shall be reported to the Operations Engineer/Drilling Superintenden

• Samples of all products used during the cementing operation shall be retained in case further tesLaboratory is required.

Note: If necessary, the key cement properties may be reported by telephone or fax.

Despatch of Cement, Additives and Water Sample

Sampling GuidelinesProper sampling of cement, additives and mixwater is essential to obtain accurate and representative tescarried out by the Drilling Supervisor.

The following guidelines should be applied:

• During unloading, the Drilling Supervisor shall take a sample directly from the supply line at a

from the silos. It is essential that the cement sampled is representative of the cement to be used

operation.

• When powdered additives samples are requested by the laboratory, they must be taken from a s

be used in the forthcoming cementing operation.

• When liquid additives samples are requested by the laboratory, they must be taken from the batcementing operation. The liquid additive must be well agitated before sampling.

• Cement, additives and water must be sampled properly and stored/despatched in the appropriat

clean.

• Excess air must be removed from the containers since exposure to humid air may affect the resu

exercise useless, potentially leading to problems during cementation.

• Samples of all products, including a 1 gal sample of the actual mixwater, must also be taken dur

operations and kept on the rig until a few days after the cement job in case the laboratory requir

of the cementation.

Samples QuantitiesThe sample quantities required are listed in the following table:

Material Quantity

Cement 10 kg

Mixwater 1 gal (2 sample bottles)

Powdered additives one full plastic bag (to be kept in laboratory)



Liquid additives 500 ml (to be kept in laboratory)

Bentonite 10 kg (to be kept in laboratory)

Sample Labelling

Cement Samples

All cement samples should be labelled with:

• rig name

• silo number

• well number

•

the type of cementation forthcoming• date received

• date despatched by flight

• expected date of first cementation.

Additive and Mixwater Samples

All additive and mixwater samples should be labelled with:

• rig name

• well number

• date despatched (to whom)

• contents

• expected date of first cementation

Cement Testing

Consistometer Test Conditions

The Pan Am(erican) Consistometer test is used. It is performed under dynamic conditions with the cemThe test conditions used are defined the following table:

Parameter Unit Definition

Depth ft True vertical depth of the cementation

Test pressure psi Expected maximum pressure during the

cementation (according to API recommendation)



Test temperature oF Expected circulating bottom hole temperature

(according to API recommendations and related to

average temperature gradient)

Slurry Composition

In general, additives for cement slurries are added to the mixwater with the exception of weighting matthe initial cement slurry or may be dry blended into the cement if batch mixing is not feasible. Dead vo

consideration when batch mixing.

The amount of dry powder additives to be used is given on the form in % weight by weight of dry ceme

amount of liquid additives in % gallons per sack (GPS). In addition the amount of water and chemicals

mixwater is also given.

The base for mixwater will be specified on the form as industrial (fresh) or sea water. The salinity of in

300 ppm chlorides.

The water/cement ratio (mixwater requirement) and slurry yield are given in cu.ft/sk.

Slurry PropertiesThe following key slurry properties are given on the cement test form:

Parameter Unit Test Details

Slurry gradient ppg

Pumpability time minutes Pan Am consistometer test measured atBottom Hole Circulating Temperature

(API tables)

Thickening time

Compressivestrength

psi Strength of the cement at cementationdepth, after the time shown, as determinedaccording to API recommended practices

HTHP fluid loss cc/30 min Determined at 1 000 psi pressure

differential and bottom hole circulating

temperature

Fann VG Meter Readings

Dial readings obtained at 600, 200, 100, 6and 3 RPM measured at BHCT to a

maximum of 200oF.

Rheology 600 rpm reading

300 rpm reading200 rpm reading100 rpm reading

6 rpm reading

3 rpm reading

Tested at standard temperatures 80o F and

457oF

Notes:

* The pumpable time of the slurry must exceed the planned job time, including mixing, by a contingenc



which may be experienced. As a general guide, one hour contingency should be used for casing cemen

back cementations.

* The final strength of cement typically used for primary cementations must be greater than 3 000 psi wshoe.

Tests at the Well Site

General Guidelines

The following general guidelines should be applied during bench tests:

Bench testing shall be carried out at the rig site since it is the main mechanism for quality control on thcomparison with the results of the Mud and Cement Laboratory to confirm that the mixwater of the rig

contaminated.

Testing must be carried out according to the procedure detailed in this section using representative sam

Testing should be completed well in advance of the job, so that time is left to make new mixwater and t

Bench tests must be carried out with samples of the mixed slurry to give an indication of when the cem

sufficiently to proceed with operations. It is important to note that the downhole pressure will accelerat

Procedure for Testing Mixwater

1. MIX 500 grams of properly sampled cement with enough mixwater to achieve the planned water/cem

the mud mixer (Hamilton Beach) at high speed.

2. PLACE the slurry in a plastic bag in a water bath controlled at expected static bottom hole temperatuis lower.

CALCULATE the expected SBHT.

3. CHECK every 15 minutes for thickening time and hardening time.

Notes:

Make sure that the mixwater/additive mixture is homogeneous before sampling.

If the cement job is delayed by a substantial amount of time, with the mixwater having been prepared e

to ensure that additives have neither settled out nor deteriorated. The bench test should be repeated sho

enough time to prepare new mixwater if required.

Spacers for cementing

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Spacers are any fluids other than cement slurry or mud, pumped ahead (preflush) or behind (postflush)

Preflushes are used to:

• prevent contamination of cement slurry with mud

• improve mud displacement and mud cake removal.

Postflushes are used to prevent:

• the plug from spinning when it will be drilled out (cement on top)

• contamination with the fluid used for displacement.

General Guidelines

The following guidelines shall be adhered to during the use of spacers:

• Scavenger slurries shall not be used if the top of cement (TOC) is critical eg., to allow for a pos

• Reduction in hydrostatic head due to spacers pumped must be carefully calculated. If the overbthe minimum required overbalance, at any stage of the cementation, a weighted preflush shall b

spacer.

• When water is used as a spacer over productive intervals, it shall be treated with 2 % KCl w/w

• Lines shall be flushed thoroughly to ensure the contamination of mud, spacers and cement slurr

• Muds requiring extra long spacers or spacers of a special composition will be advised by the M

• If oil has been added to a water base mud for any reason, then +/- 2 % v/v surfactant should be

• In general, plug flow and plug flow spacers are only used for stinger cementations where turbul

cannot be achieved.

• It is preferable to pump spacers between cementing plugs.

Preflush Formulations

Cement scavenger slurries are dilute mixes of cement and water, pumped ahead of the cement slurry inremove gelled mud and filter cakes. The following guidelines shall be used when pumping scavenger sl

• The gradient should be between mud gradient and the main cement slurry gradient with a maxim

Cement Contractor should be consulted for the optimum gradient.• To prevent fast setting of the scavenger slurry, a cement retarder shall be added to the mixwater

mixing logistics.

Recommended Preflushes for Water Based Muds



High Annular Velocity Displacements

The recommended preflushes for water based muds for high annular velocity displacements are given i

Application Pumping

Order

Spacer Size

(annular

length)

Spacer Type

20in casing - - -

Intermediate casing13.3/8in / 9.5/8in

1 500 ft Sea water / Industrial water

2 500 ft Sea Water or spacer /

scavenger slurry (10 ppg)

Production casing

/liner 4.1/2in / 7in

1 500 ft Spacer

2 500 ft Scavenger slurry (10 ppg) /Dual spacer

Cement Plugs and Squeezes

The recommended preflushes for fresh water muds when setting cement plugs and squeezes are given i

Mud Type Pumping Order Spacer Length

(annular length)

Spacer Type

Water based mud 1 300 ft ~ 10bbls Fresh water

Postflushes

Standard Cementations

In standard cementations, after the top plug has been dropped cement slurry should be pumped behind t

when it is being drilled out.

The postflushes listed in the table below should be used in all cementations including plugs and squeez

Number WBM OBM Size (ft)

1 Cement Cement 35

2 Fresh water Base Oil 500 or 10 bbls

Cementations Using Stinger

The postflushes listed in the table below should be used in all cementations in including plugs and sque

Number WBM Size (ft)

1 Fresh water As required to balancecement plug



menting Job - Preparation Guidelines

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This article presents guidelines for: 1. Treatment of Mud Prior to Cementing, 2. Hole Volumes and Slur

Treatment of Mud Prior to Cementing

Before pulling out of hole to run casing, the hole shall be circulated clean (150 % of casing contents) un

To improve displacement efficiency, the mud shall be conditioned to reduce the rheology during circula

Solids control equipment shall be run to remove drill solids from the mud thus reducing PV to the lowe

Dispersants / thinners shall be added to reduce the YP and 10 minute gel strength. (YP not reduced in h

The mud must be completely free of gas after circulating. Circulation must be continued until a full ann

Hole Volumes and Slurry Volume Calculations

Cementations shall be based on volumes calculated from a calliper log (plus 10% excess) if available. T

If off-scale washouts occur, make a best guess of hole volumes. Most calliper logs will give an integrat

previous casing shoe as a check. In the case where an integrated hole volume is given, the tool should b

Circulation Test

Prior to a plug type cementation, at least 150 % of the casing content must be circulated. During this cir

Commence circulation at a very low rate.

Increase flow rate in increments of 2 bbls/min or to limitation due to ECP’s.

After each increase, wait at least five minutes to observe for losses and to allow pressures to stabilise. E

Reduce the pump rate as soon as losses are observed or as soon as the maximum equivalent circulating

In addition, a check shall be made on the circulation pressure at the rate that will be used to bump the pl

Notes:

The surface pressure losses through the wellhead and return surface lines must be included. No general

If losses are observed at a rate substantially below the maximum rate as predicted with regard to ECD c

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a rate where slight losses are induced. Once the losses have stopped, the rate can be carefully increased

When running 7” hydraulic hanger and ECP circulation rate and pressure depends on rating of shear pin

Coarse LCM is not to be used before cementing due to risk of plugging the float equipment

Cementing Checklists

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(6 votes, average 4.17 out of 5)Cementing Checklists for planning, during and after cementi

PRE-JOB Checklist

• Water sample sent to town for analysis

• Pre-job safety brief held with all parties

• Bottom hole temperature from logs consistent with no

• Caliper run. Is hole under/in/overgauge

• Casing drifted, threads clean, consumables in place a

• Strokes to bump

• Plan to monitor returns/ losses

• Contingency for losses - minimum turbulent flow, ma

• Open-hole excess volume determined

• Cement and additive stocks sufficient

• Chemical inventory before slurry and spacer preparat

• Has the Cementer been told how much excess mixflu

contingency

• Cement truck checked out and run recently

• Cement calculations done by at least 2 people and cro

• Spare chicksans available on floor or catwalk

• Plug dropping head and plugs inspected. Operation o

• Loading of PDH witnessed by Drilling Supervisor. V

• Strokes to bump plug and strokes to fill pipe calculate

• What is the plan for handling fluids at surface. Can p briefed

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• Radios checked

• Stroke counter functioning OK

• If displacing with rig pump, use one pump only.

• Double the chemical requirements calculated availab

•

Check water to be used (salt content is too high/ Mg l• Set the oven to the test temp. before the job starts.

• Discuss the complete job when contractor arrives on

• Be present when the cement chemicals are being adde

occurs).

• Calculate:

o 1. the volume and strokes to cement equalised

o 2. the expected differential pressure at bump.

o 3. based on the planned height of cement in th

• Litecrete: re-blend and test the dry blend cement at th• Litecrete: “more” mix water must be prepared.

• Preprare several copies of the cement program Make

• Cement samples sent to town

• Have cementers check stock for next casing job

JOB PLANNING Checklist

• BHST and BHCT consistent with recipe

• Spacer’s compatibility been checked

• Is fluid loss additive required? It is cheaper to use sta

• If a new system is introduced, has a sensitivity test be

• Are the spacers recommended cost effective

• Is free water acceptable (high angle cementation onl

DURING JOB Checklist

•

Note times of arrival of contractor and other significalines, plug dropped, bumped etc.).

• Have with you the program and the pre-calculation, a

• Set up non-oral method of to advise cementer of slurr

• Use rig personnel to assist with monitoring job

• Sampling: - take two samples of final slurry, one to bin and two out of the oven.



• If a tail slurry is planned take 2 samples also.

AFTER JOB Checklist

• Prepare a cement job report and send to Drilling Supe• Have cementers rig down equipment as soon as possi

• Insure that personnel do not remain on the wellsite if

• Confirm chemicals used and returned.

Cement Additives (function and definition)

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This article describes the function of the various classes of cement additives and also to highlight w purpose.

The additives to be used and their concentration shall be decided by the Cement Contractor, after te

samples of cement, additives and mixwater despatched from the rig. This has to be then approved b

Superintendent.

No deviationfrom the recipe, as determined by the Cementing Contractor is permitted unless speci

the Superitntendent.Note: % BWOC it means “percentage by weight of dry cement”. One sack of cement is 94lbs.

Accelerators

Accelerators may be added to the mixwater to reduce the thickening and setting times of the slurry,unnecessary time spent waiting on cement.

Calcium Chloride is the most common type of accelerator used. Other, less frequently used acceler

Potassium Chloride.

Additive Formula Concentration Comments

Calcium Chloride

(Accelerator)

CaCl2 1 - 2 % BWOC High gels may form at higher

concentrations. Flash setting mayoccur above 3 %.

Sodium Chloride

(Accelerator)

NaCl Up to 20 lbs/bbl

of mixwater

Acts as an accelerator and

adversely affects other additives

at higher concentrations than 20

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lbs/bbl.

Sea Water

(Accelerator)

Use as mixwater Contains NaCl in the correct

concentration range. Main

application is shallow depthcementation offshore.

Potassium

Chloride

KCl As required Equivalent to NaCl and CaCl2 but

more expensive.

Notes:

1. In general accelerators increase the viscosity of the cement slurry and decrease the effectiv

2. Calcium Chloride can cause skin burns and sever irritation to eyes, nose and lungs. Glovesduring mixing. Calcium Chloride is available in 50lb sacks.

RetardersAs the temperature increases, the chemical reaction between cement and water is accelerated which

Increased depths and formation temperatures may require the use of retarders in order to extend the

Thixotropic slurries may require retarders at shallow depths and low temperatures.

Effects on Viscosity

Most retarders affect the viscosity of the cement as follows:

Type of Retarder Effect on Viscosity

Lignin Derivatives (HR 5, HR 6 etc) Reduce

Organic Acids Reduce

Cellulose Derivatives (CMC) Increase

Note: The combined use of retarders and accelerators in the same mix should be avoided.

High Density Additives

There are two main methods of increasing the gradient of the cement slurry:

• reducing the water/cement ratio

• addition of a weighting material.

Reducing the Water/Cement Ratio

This is the preferred method of increasing cement gradient, particularly when cementing across gas



approximately 17.0 ppg can be attained by this method.

Addition of a Weighting Material

The preferred material is hematite (iron oxide) but barite may also be used. It is preferable to batch

material rather than to use pre-blended cement since weighting materials additive in pre-blended ceFurthermore, handling different blends of cement on one rig may result in operational mistakes.

Note: When drilling with a mud gradient of 14.8 ppg or more, a batch mixing unit and sufficient w

contingency. If very large volumes need to be mixed, batch mixing is not achievable

Low Density Additives (Extenders)

Low gradient slurries are used for cementing weak formations or when there is a possibility that th

heavier slurry was used.

Preparation

A low gradient slurry is prepared by adding extra mixwater. Bentonite is usually pre-mixed at a con

freshwater to reduce free water separation of the resultant slurry.

Bentonite must be fully hydrated before any other additives are added to the mixwater. To achieve

industrial water or dry bentonite may be hydrated in industrial water. In the latter case, the minimu

may be longer, depending on the type of bentonite used. Consult the Cementing Contractor for exp

type of bentonite for best results is Wyoming bentonite.

The bentonite content must be checked using the methylene blue test (MBT).

Compressive Strength

As a result of the decreased cement concentration of extended slurries, the compressive strength of

than that of neat slurries.

Friction Reducers (Dispersants or Thinners)

Friction reducers are dispersing agents which can be added to the slurry to reduce its viscosity and

the system while displacing (or squeezing) the cement. As a result, higher pumping rate are possiblefficiencies may be achieved

Fluid Loss Control Additives

Fluid loss control additives are added to cement slurries for the following reasons:



• To reduce the possibility of dehydration opposite porous zones and consequently flash setti

• Loss of fluid from the slurry will result in increasing slurry viscosity and gradient and high

• Excessive fluid loss will reduce slurry volume and give less cement fill.

• When squeeze cementing it is desired to get an effective squeeze against the entire formatiointo it.

Most fluid loss additives tend to viscosify the slurry and consequently, dispersants are often added

Additives for Thixotropic Slurries

The main application of thixotropic slurries is cementing in lost circulation environments.

During pumping the slurry behaves as normal, however, a gel structure develops rapidly when stati

in cementing across gas zones.

The major disadvantage of thixotropic slurries is their relatively high viscosity which may adversel

Defoamers and Antifoams

While mixing cement, and/or when preparing mixwater, containing retarders, salts, fluid loss additi

often experienced. To control such problems antifoams and defoamers are available.

Antifoams should be used before adding any other chemicals.

Defoamers remain effective when added after foam-causing chemicals.

In practice, such distinction may be difficult to ensure and therefore both antifoams as well as defo

re-circulating cement mixer.

Gasblocking Additives

During the hardening process, the cement slurry passes through a semi-solid phase in which the liq

overburden pressure will be lost thus permitting gas migration into, and through, the cement matrix

Surfactants added to the slurry will form a stable foam with the gas bubbles preventing their transp

Additives may be incorporated into the slurry which act to block the gelled cement pore structure p

Cementing Job - Preparation Checklists•

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(5 votes, average 4.20 out of 5)This article presents Cementing checklists for Drilling Supervisor, Mud Engineer, Driling contractor an

Checklist for Drilling Supervisor

# Time Description Post-job remarks

1 5d Cement proposal checked/acceptable.

2 3d Cementer called out. Competence verified through the Contractor

Base Manager.

3 2d Proposal approved by ODE/1X.

4 6h Tasks appointed; Scenario ready.

5 6h Diagram of all lines / valves OK and checked.

6 6h Annotated execution flow chart ready.

7 1h Hole OK. (Clean, losses cured, overbalance OK).

8 1h Mud OK (Rheology in spec., mud mobility in annulusmaximised).

9 1h Mixwater and spacer checklist OK.

10 1h Rig Eqt. OK. (Compressor, Transfer-and Mud Pumps, Silo's)

11 1h Cement Eqt OK. (Cmt Unit, Cmt head, Surface/ Lines)

12 1h Plugs and launcher OK (plugs, P test, Ids of cocks, XO, DP, etc.

for liner).

13 1h Safety Eqt OK. (Dusk mask, Goggles, Earplugs, Gloves, Eye

Wash, Fire Fighting)

14 1h All involved Personnel briefed; 'What if' discussed with key personnel.

15 1h Check lines/valves (tanks, cmt unit, surface (P test), return)

16 5d Send samples of water, cement and additives to lab . Label

and telex.

17 5d Send cementation form to lab. Preliminary recipe received.

18 2d Received recipe for cement and weighted spacer from lab.19 2d Prepare cementation programme.

20 1d Update cement programme with caliper and temperature from

logs. The Lab must be informed of any variation from

estimated temperature.

21 1d Compare job calculations with those of Cementer.



22 2h Perform circulation test. Establish pressure at bump rate.

23 1h Dust mask, gloves and ear and eyes protection, eye wash.

Checklist for Mud Engineer


1 1d Fill mixing tank with water to required level and check chlorides

<400 ppm.

3 1d Check quantity of additives as they are added to tank. Recordquantity and sequence.

4 1d Record level of mix water tank after adding additives

5 1d Perform bench test with mix water with representative cement

sample.

6 2h Check that the mud rheology is within specifications of the WellProgramme.

7 2h Calibrate time gradient with pressurised mud balance plus back-up standard mud balance.

8 1h Check level of mix water tank prior to cementing for anyevidence of contamination.

9 1h Water bath set at correct temperature.

Checklist for Rig Equipment by Drilling Contractor# Time Description Post-job remarks

Air Compressor

1. Power end.

2. Pressure.

3. Volume.

4. "Dryness".

5. Relief valve.

6. No leaks in system (last test date/pressure).

Transfer pump

1. Impeller check (dry run).

2. Leaking shaft seals (false air).

3. Electrical switches.



4. Lines flushed.

Mud pumps

1. Relief valve (pressure test).

2. Control power supply, switches.

3. Pistons OK (pre job cleaned).

4. Liners OK (pre job cleaned).

5. Valves OK (pre job cleaned).

6. Suction lines/strainers (pre job cleaned).

Tanks

1. Line up to cement unit OK.

2. No leaks on tank or valves.

3. Level indicators OK. Surface lines

1. Pressure test .

2. Size adequate (avoid bottlenecks).

3. Cement dump line operational.

4. Ensure that valves in lines are in good condition.

Manifold

1. Hook up as on diagram.

2. Integrity of the valves OK.

3. Check lines (flushed/clean).

4. Contingency lines clean and ready for hook up.

Return line

1. Lined up as per diagram.

2. No Leakage’s into line from outside

Cement silo's

1. Pre fluff and circulate around. Surge tank

1. Maintain pressure differential.

Checklist for the Cementer




General

1. Job calculations done.

2. Chemicals quality and quantity checked.

3. Dust mask, gloves and ear, eyes protection; fire extinguisher,

eye wash station.

Pre-Job

1 Check quantity / appearance of cement and additives

2 Flush lines from mix tank to cement unit with water

Cementing unit

1. Air system - check air cleaner, lubrication, tanks and drain

moisture.

2. Diesel fuel - check level, drain water and sediment from

bottom.

3. Engine oil - check level twice for consistency.

4. Radiator/heat exchanger - water level.

5. Fire hose for cooling engine stand-by.

6. Fan belt - tension, crack or damage.

7. Transmission oil - check level.

8. Chain case oil - check level.

9. Power end oil - check level.

10. Hydraulic oil - check level.

11. Plunger oiled - check reservoir tank level and alemite pump.

12. Gauges - check for operation.

13. Emergency kill system - check operation.

14. Pneumatic operating butterfly valves - check operation.

15. Centrifugal pumps - bearing oil level, packing seal, impeller

(dry run),

16. Output pressure and rate.

17. Pressure sensor diaphragm - pumped up and leak-free.

18. Start engine - check starter.

19. Circulation - check for strainer, suction and discharge lines.

20. Valves condition.

21. Over pressure shutdown system - check operation by



pressuring.

22. Pressure test - test unit to 1,000 psi. above expected working

pressure.

23. Sensors - pressure, gradient and flow rate, calibrate if

necessary.

Re-circulating mixer

1. Slurry tub - strainer, clean and cement-free.

2. Knife gate (metering valve) - check operation, grease.

3. Mixing bowl - correct jets size.

4. Centrifugal pump - check for output pressure and rate, leaks onseal, wear in bearing

5. Check operation of cement, water quick shut off valves &

recirculating valve.

Batch Mixer

1. Centrifugal pump - check for output pressure and rate, leak on

seal, wear in bearing

2. Paddle - operational.

3. Electric motor - cables, switches, coil resistivity test.

4. Chemical hopper - clean, jets good, lines clear.

5. Dry cement inlet - clean and operational.

Surge Can1. Check can clean and empty.

2. Pre fluff through air jets and blow clear through vent line.

3. Check all gauges, zero the gradient indicator.

4. Load cell - pumped up, leak-free.

5. Sight glasses - clean and not cracked.

6. Hatch cover - hinges, bolts secured, leak-free.

7. Relief valve - check last serviced and tested.

8. Check all lines, jets, hoses and check valves.

Cementing heads

1. Correct size - pressure rating (stump test).

2. Manifold valves - greased, pressure tested.

3. Plug retainers - greased, operation.



4. Plug release indicator - operation.

5. Cross-over - ‘o’ rings, correct thread.

6. Circulating heads - non welded, pressure rating.

7. Check quantity/appearance of cement and additives

109515084 7 linner cementing

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