Review of Petroleum Occurrence and Prospects of Pakistan with Special Reference to Adjoining Basins of India, Afghanistan and Iran
Pakistan is endowed with three major sedimentary basins (covering more than 2/3 of Its total area) namely, Indus In the east which extends east and south-eastward Into India; Balochlstan In the west which continues northward Into Afghanistan and westward Into Iran; and Pishln In the northwest which Is spread Into Afghanistan. The two basins, Indus and Balochistan are separated by a north-south trending Bela-Ornach-Chaman transform fault zone while the Pishin Is perched in between this fault zone and the Indus basin. Indus is the only producing basin of Pakistan where 83 oil and gas fields have been discovered.
Review of data Indicates that In Balochistan basin some speculated petrolifero us plays could exist In Eocene-Plio-Pleistocene clastic/carbonate reservoirs which are probably filled with oil and gas charged from Interbedded shales as well as from underlying formations. The oil and gas In southern part of the Indus basin had been mostly formed In Early Cretaceous shales deposited during rifting phase and generation probably took place as early as Paleocene. In the northern part of the Indus basin most of the oil was generated from Paleocene source rocks which were deposited In restricted marine conditions created by compression related to first episode of collision. The structural styles In Indus basin from Its southern to northern areas change from fault traps associated with Cretaceous block faulting to inversion of extensional features and to younger compressive structures produced by collision, subduction and thrusting. Tertiary flysh thrown into complex structures In Pishin basin appears to have speculative potential for containing hydrocarbons as the basin has not yet been explored.