Hydrocarbon Potential of Marwat and Khisor Trans Indus Ranges, Northwest Pakistan

Khan, Mudassar Z.; Khan, Moin R.; Raza, Ali
Exploration, Pakistan Petroleum Limited, Karachi, Pakistan.

Fold and Thrust Belts throughout the world are the most significant areas for hydrocarbon exploration and exploitation. These fold and thrust belts, which have globally been explored for hydrocarbons for over a century now with mixed results, have become even more challenging frontiers for hydrocarbon exploration because of the steeply increasing exploration cost and risk. Though, acquisition of 3D seismic data have contributed a lot to the understanding of complex geometries in the fold-thrust belts in subsurface, challenges are still there for exploration geoscientists. The Himalayan foreland fold & thrust belt of Pakistan includes Kohat foreland fold-and-thrust belt along with its associated frontal ranges to the west of the Indus River that include Surghar-Shinghar, Marwat-Khisor, Bhittani and Manzai (Trans-Indus ranges), Northern Sulaiman Range and the D.I. Khan Plain in the south. This compressional structural domain has yielded several significant discoveries of oil and gas albeit more than a dozen dry wells. The Marwat and Khisor Ranges remain devoid of any commercial discovery, though the first exploration well Kundal-1 drilled in the subcontinent in 1866 (only 7 years after the birth of modern oil industry in Pennsylvania), was located near the most prolific oil seepage of the region in the foothills of Khisor Range. Critical review of the available literature and geological field work in Marwat-Khisor Range depicts that all the ingredients of a working petroleum system exist in the area. The petroleum system of the area is characterized by multiple reservoirs and sealing horizons that are likely to be charged by multiple source rocks. Surface structural style shows that en-echelon anticlinal closures developed within the hanging walls of major faults could provide primary traps for hydrocarbons. In addition, sub-thrust plays as well as stratigraphic traps (formed as a result of eastward truncation of various horizons) may also provide potential drillable prospects. The presence of a regional hydrocarbon kitchen is well supported by the stratigraphic record, whereas the oil and gas discoveries along with oil/gas seepages in the surrounding fold belts provide clear indication of the optimum timing of hydrocarbons generation, migration and entrapment in the area. The key to success would be correctly deciphering the subsurface geometries and eventually precisely locating the trap culminations.

AAPG Search and Discovery Article #90155©2012 AAPG International Conference & Exhibition, Singapore, 16-19 September 2012