atc 2011-hydrocarbon prospect of balochistan

Moin Raza Khan

General Manager Exploration

PAKISTAN PETROLEUM LIMITED

. City.

Prospects of Balochistan Basin Revisited – New Model Proposed vis-à-vis its Implication for Hydrocarbon Prospectivity

ANNUAL TECHNICAL CONFERENCE

2011

ENERGY SECURITY THROUGH INDIGENOUS RESOURECES

Coauthors: Noushaba Hisam, Abid H. Baitu & Mudasar M. Saqab

TALK OUTLINE

• Introduction

• Geological History and Geodynamic Evolution

• Exploration History

• Tectonic Models – Previous & Proposed

• Structural Style

• Stratigraphy and Petroleum Play System

• Analogues

• Conclusion

ANNUAL TECHNICAL CONFERENCE 2011

Slide 1AUTHORS: Moin Raza KhanProspects of Balochistan Basin Revisited – New Model Proposed vis-à-vis its Implications for Hydrocarbon Prospectivity

• Balochistan Basin lies to the west of Chaman Transform Boundary and

regarded as a subduction complex of Arabian Plate under Makran Continental

Margin

• Divided into two main prospective zones

• Makran Accretionary Prism:

Extraordinary thick and wide (450 km)

Neogene rocks are exposed in the onshore part

Many active mud volcanoes, emanating methane gas, are present

Relatively more explored, both onshore and offshore

• Kharan-Mashkhel Trough / Fore Arc Basin (FAB):

About 150 km wide and 300 km long (approx. area is 30,000 Km2)

Covered by superficial deposits of Kharan Desert

Kwash Oil Seep (near Iran border) and sharp fetid smell in Eocene limestone

indicates hydrocarbon generation

Unexplored

• Subsurface geophysical data (gravity, magnetic and seismic) evaluated to understand

the structural geometry, sediment thickness and depth of basement in Kharan FAB

• Seismic data show presence of high angle reverse faults

Introduction



• Subduction of Arabian Plate

underneath the Makran

Continental Margin resulted in

the formation of following

tectonic elements from North to

South:

Chagai Magmatic Arc

Dalbandin Trough

Raskoh Range

Kharan Fore-Arc Basin

Panjgur Wrench Zone

Makran Accretionary

Prism

Makran Trench

Location Map



• Cretaceous: Intra-oceanic subduction & submarine eruption (Sinjrani – Kuchakki

volcanics)

• Paleocene: Development of deltaic fans with provenance in ZVT and axial belt

which resulted in deposition of Rakhshani Formation

• Eocene: Deposition of Kharan Limestone on the Paleocene fan complex. Deep

marine sediments in Siahan Range

• Upper Eocene-Oligocene: Rejuvenation of clastics (Nauroz Fm and Pishi Group

in north; Siahan Shale and Panjgur Sandstone in south)

• Late Oligocene-Miocene: Development of a large delta with provenance in

Indian collision zone (Khojak/Makran Fan). Convergence of Arabian Plate started

• Miocene: Sinistral movement along Chaman Fault. Thrusting of ophiolites and

Kuchakki Volcanics in the northern Raskoh Range

• Pliocene: Deposition of Dalbandin Formation in Kharan and Dalbandin troughs

• Pleistocene-Recent: Progressive shift of deformation to the south i.e., in Siahan

Range and Makran Accretionary prism. Deposition of alluvial fans and desert

dunes in Kharan Trough

Geological History



• Indentation of the Indian Plate in Eurasian Plate during Late Tertiary

resulted in the present day tectonic settings

• It is major controlling factor for the presence of hydrocarbon plays;

deposition of prolific source, reservoir and seal facies, associated with

huge overburden providing for the maturity of source rocks

• Eastern and Western margin appear to be the mirror image of each other

• Eastern margin producing hydrocarbons while western margin is still

barren

Geodynamic Evolution


Slide 1AUTHORS: Moin Raza Khan

Late Cretaceous 80 Ma Eocene 50 Ma Miocene 20 Ma

Prospects of Balochistan Basin Revisited – New Model Proposed vis-à-vis its Implications for Hydrocarbon Prospectivity

Exploration History



-RAGUP

JALPARI-01

• Pioneering geological reconnaissance made by

Geological Survey of India (Vrendenburgh, 1901)

• Hunting Survey Corporation (HSC) conducted geological

mapping and established lithostratigraphy (HSC, 1960)

• Airborne gravity/magnetic surveys conducted in 1962-

63,1976-77 and 1999 over Kharan Basin

• OGDCL (1993-96) acquired 507km of 2D seismic data in

the NE part of Kharan Fore Arc Basin

• About 24,000 line km 2D and 4,000 sq. km 3D seismic

data has been acquired

• Nine exploratory wells were drilled in the region, mainly

offshore, with no hydrocarbon discovery

• Hydrocarbon exploration activity focused in Makran

Accretionary Prism

• It is suggested to focus the exploration efforts in the

Kharan Basin where petroleum systems are likely to be

effective


Previous Tectonic Models - Comparison



Proposed Tectonic Model



Sedimentary Thickness & Tectonic Style



Satellite Gravity Map Fault Plane Solution


Structural Style



Chagai Volcanic Arc

A

B C

D

E

F

A BC D

E F


Stratigraphy and Petroleum Play Systems



N S

N

S

Source

Reservoir

Seal

Two Petroleum Systems:1. Paleocene-Eocene (Rakhshani-Kharan)

Composite Petroleum System

2. Eocene-Oligocene (Siahan) Petroleum System

Four Petroleum Plays:i. Kharan Limestone Play

ii. Rakhshani Sand Play

iii. Siahan Sand Play

iv. Panjgur Sand Play


Total Petroleum Systems of Kharan N & S



Total Petroleum

System of

Northern Kharan

Total Petroleum

System of

Southern Kharan


Analogues



• Kharan FAB is the most prospective part of Balochistan Basin

• Paleocene-Recent sedimentary sequence is present having

considerable thickness

• Structures related to compression with some strike-slip component

are likely to provide trapping mechanism

• Two petroleum systems and four plays have been identified

• Geothermal gradient and depths are favorable for maturation of

source rock and generation of hydrocarbon

• Cook Inlet Basin of Alaska and Salin Basin of Myanmar are producing

analogues of Kharan FAB

Conclusion





Thank You . . .


Backups Slides



• Dolan et al assumed Raskoh Range as Magmatic arc and marked a large

pluton beneath it which deformed overlying rocks and formed a big anticline.

They did not show the thrust sheets present in the north of Raskoh range

where Kuchakki volcanics are thrusted over Nauroz Fm of Oligocene (see our

poster of one day your visit to Kharan GFW). This part of Dolan model is not

evident from any reviewed and collected data. Other parts like two

subductions zones and folded/ thrusted strata from Oligocene to Pliocene are

logical and evident that is why we adopted this model as base for ours.

Presence of such a large pluton in Raskoh area may lead somebody to

assume warmer thermal history for Kharan FAB which may or may not be

suitable for HC prospectivity ( suitable as in Salin Basin, we have intrusion

close to discovery - see Salin Basin Cross Section).

Dolan et al., 1987:



• Raza et al., 1991 have presented one of the most complex models for a

convergence margin. According to them, continental crust extends to just north

of Makran coast beneath thick deformed sedimentary package. About 15km

highly deformed sedimentary complex has been interpreted by them which led

them to repeat sedimentary package more than 10 times at places. At the same

time they interpret normal faults within Kharan FAB which contradict the

deformation of such a high intensity. Seismic line passing through the Kharan

FAB also shows reverse fault and folded strata. Geological history presented by

Raza et al no doubt enhanced the prospectivity of less deformed Kharan FAB

but it does not represent the ground reality. So we have constructed fold/thrust

model in Kharan FAB and interpreted oceanic crust as evident during GFW.

Raza et al., 1991:



• Rafferty et al., interpret Andean type subduction of Arabian plate under

continental margin of Afghanistan Plate marks a big pluton under Raskoh

range. He shows some compressional structures above this pluton as they

have visited the southern half of Raskoh Range. They mark a suture zone

within Kharan Forearc basin which is not evident on seismic line. So we have

followed the seismic line evidence and not marked the suture in Kharan FAB.

If we have suture in Kharan FAB then the prospectivity will be very low or zero

because suture zone are rarely prospective

Rafferty et al., 2000:



• Siddiqui has presented the logical geological history on the basis of detailed

stratigraphic and geochemical analysis of intrusive rocks. He showed oceanic

– oceanic subduction with presence of thick Kuchakki and Sinjrani volcanics

and overlying Paleocene – Oligocene strata on overlying plate. Presence of

pluton within the thrust sheets provided evidence that all the structuration in

Raskoh and Kharan FAB is younger than plutonic activity. This evidence

contradict the Rafferty and Dolan models as they make a pluton under

Raskoh range and attributed deformation to this Pluton. Our model is more

elaborative than Siddique's model as we have elaborated our interested area

and focused on stratigraphy and structure style of southern Raskoh for

interpolating it into Kharan FAB.

Siddiqui, 1991:



• We are assuming oceanic crust beneath Raskoh Range and Kharan FAB

(oceanic-oceanic subduction not Andean type)

• We have modified the plutonic activity in Raskoh Range and restricted it to

northern part

• The plutons and Kuchakki volcanics were thrusted southward on sediments of

Paleocene – Oligocene

• Southern part of Raskoh Range is a basically deformed part of Forearc basin and

we are expecting the similar kind of stratigraphy and structure in Kharan FAB

• Deformation decreases from north to south and it is gentle in the Kharan FAB

while it increases again toward south as another deformational front of Siahan

Range is present

Our key assumptions:



• Balochistan

Introduction



atc 2011-hydrocarbon prospect of balochistan

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