SOURCE AND RESERVOIRROCKS OF PAKISTAN

Muhammad Zahir Kakar EIP-78

Ahtisham Ul Haq EIP-107

Rafiullah Khan EIP-108

Introduction Of Source Rock Source rock refers to rocks from which hydrocarbons have been generated or

capable of being generated.

They are organic-rich sediments that may have been deposited in a variety of environments including deep water marine, lacustrine and deltaic.

Typical source rocks, usually shales contain about 1% organic matter

Rocks of marine origin tend to be oil-prone, whereas terrestrial source rocks (such as coal) tend to be gas-prone.

Under the right conditions, source rocks may also be reservoir rocks, as in the case of shale gas reservoirs.

A source rock is formed by the:

Sedimentation in areas of high organic productivity.

Preservation of organic matter in sediment.

Introduction Of Reservoir Rocks A fundamental property of a reservoir rock is its porosity.

However, for it to be an effective reservoir rock, the fundamental property is permeability.

Both porosity and permeability are geometric properties of a rock and both are the result of its lithological (composition) character.

The physical composition of a rock and the textural properties (geometric properties such as the sizes and shapes of the constituent grains, the manner of their packing) are what is important when discussing reservoir rocks and not so much the age of the rock.

Sedimentary Basin Basin is region of the earth of long-term subsidence creating accommodation

space for infilling by sediments.

Pakistan comprises three sedimentary basins.

Indus Basin: (1) Upper Indus Basin (2) Central Indus Basin

(3) Lower Indus Basin

Balochistan Basin

Pishin or kakar khorasan Basin

The Upper Indus Basin (UIB)is the area covering Potwar-Kohat plateau in Punjab and Khyber-Pathtunkhawa provinces in Northern Pakistan (districts, Jhelum, Chakwal, Rawalpindi, Islamabad, Attock,Kohat, Karak area).

The central indus basin is separated from upper indus basin by the Sargodha high and pezu uplift in the north.

It is bounded by indian shield in the east, marginal zone of Indian Plate in the west, and Sukker Riftin the south.

The south indus basin is bounded by the indian shield to the east and the marginal zone of Inian plate to the west.

Pishin basin is also called kakar khorasan basin.

Kakar khorasan basin is located between Chaman fault in the north and northwest and obducted ophiolitic margin of Indian Plate in the south.

In the east Balochistan basin is separated from Indus basin by chaman fault, whereas the western part extend into Iran.

Basin Map Of Pakistan

Source Rock Of Upper Indus Basin

The Paleocene Patala Formation appears to be the primary source of

hydrocarbons.

There are several potential source rocks in the Kohat-Potwar geologic

province. These include the Late Proterozoic–Lower Cambrian Salt Range;

Permian Wargal, Sardhai, and Chhidru; Paleocene Lockhart; and Eocene

Patala Formations (OGDC, 1996; Quadri and Quadri, 1996).

Chichali and Lumshiwal Formations may be the youngest mature rocks with

source potential throughout most of the Kohat Plateau.

Reservoir Rock Of Upper Indus basin On the Upper Indus basin, oil or gas has been produced

from the following formations:

Cambrian Kherwa, Kussak, and Jutana;

Permian Tobra, Amb, and Wargal;

Jurassic Datta;

Cretaceous Lumshiwal;

Paleocene Khairabad, Lockhart, Patala, and Nammal;

Eocene Bhadrar, Chorgali, and Margala Hill Limestone;

Miocene Murree (Khan and others, 1986; Petroconsultants, 1996).

Oil and Gas Field

The Potwar thrust belt has been known for oil production since 1915 when Khaur field was discovered in district Attock about 100 miles south of Rawalpindi.

The oldest reservoir for oil, gas and condensate is Khewra formation’s sandstone of Early Cambrian age in Adhi field near Gujar Khan district Rawalpindi in Potwar Basin.

The carbonates of Chorgali-Sakesar Formation of Eocene age are the biggest reservoir in Potwar Basin. The major fields where Eocene fractured carbonates are reservoirs, Dhulian, Meyal, Pindori, Pariwali, Dhurnal, Dakhni, Balkassar, Chak naurang, Adhi, Bhangali and Fim Kasser.

Missa Kiswal and Rajian field are also producing oil from Khewra sandstone; both located not far away from Adhi field.

Late Permain carbonates of Wargal Formation is the reservoir in Dhurnal field. This reservoir is natural fractured. Dhurnal field is also located in PotwarBasin near Khaur field.

Source Rock Of Lower Indus basin Total area of lower indus basin is 169,000 ml2.

Sember (Cretaceous) and Ranikot (Paleocene) are main source rock.

Environment of deposition of Sember and ranikot is marine environment.

But there are units with Lower Goru, Ranikot and Ghazij Formation to be source rock as well.

There are other known and potential source rocks.

Permian Dandot and Tredian Formations,

Triassic Jurassic Datta Formation,

Eocene Ghazij Formation,

lower Miocene shales.

Reservoir Rock Of Lower Indus basin

In Kirthar Range mostly Pab sandstone is the reservoir.

Lower Goru Sands (Lower Cretaceous) are the main reservoir for oil and gas.

Habib Rahi limestone (Eocene ) is the gas reservoir in the giant Mari Field.

These fields produce from Sui Main Limestone (SML, Eocene), Ranikot sands, Dungan limestone (Paleocene) and the Pab sandstone ( Late Cretaceous).

Oil and Gas Field

Lower Goru Formation Upper sands and Basal sands are oil bearing in more than 50 fields in the Badin area in the districts Mirpurkhas, Hyderabad, Badin and Sanghar in Sindh Province. (Khaskheli, matli, Tando Adam, Turk, Duphri, Kato, Lashari, Bhatti fields, etc)

Source is Sembar, Reservoir is Sui Main Limestone (Sui, Kandhkot, Loti, Kandra, Bhadra fields).

Habib Rahi limestone (Mari gas field).

Along Kirthar Range (Mazarani, Mehar, Zamzama, Bhit, Badhra gas fields) Pabis the reservoir for gas.

Source Rocks Of Balochistan basin

Balochistan basin is a least explored area.

Pajgur formation (Miocene) is considered as a reservoir.

Hoshab and Parkana formation has also ability as reservoir rock in balochistabbasin.

Reservoir Rocks Of Balochistan basin Talar sand stone has high porosity act as reservoir rock.

Thank you