Reservoir Potential of Marwat and Khisor Trans Indus Ranges, Northwest Pakistan
The Marwat-Khisor ranges constitute the central part of the Trans Indus ranges. These northeast trending fold-thrust belts represent the leading deformational front of the Kohat fold and thrust belt and form the southeastern border of Bannu Basin. Marwat Anticline constitutes the main topographic expression of the area along with frontal Khisor thrust. The Marwat Range hosts Siwalik rocks throughout its map trace, whereas exposed stratigraphy of the Khisor Range comprises Cambrian to Jurassic platform sediments, which are unconformably overlain by fluvial sediments of Siwalik Group. Exploratory wells drilled in the area along with surface geology provide information about the regional stratigraphic record. The sedimentary rock assemblages outcropping along the Trans Indus Range indicate a fairly quiet period of continuous sedimentation in a shallow sea with the down-sagging of the Kohat-Potwar Basin, occasionally interrupted by localized uplifts, resulting in unconformities. Multiple potential reservoirs are present throughout the stratigraphic sequence in the Trans Indus ranges ranging in age from Cambrian to Cretaceous. These mainly include shallow marine / deltaic clastics of Mesozoic and Paleozoic. This paper attempts to share our updated understanding about the potential of different reservoirs within the region in terms of their depositional settings, thickness, depth and more importantly their overall hydrocarbon potential. This would help evaluate the risks involved in exploration, based on our recent experience of exploration work and making use of available well data, field observations, petrographic analysis, source rock analysis, and basin modeling. Recognition of continuity in facies along with approximation of depths to different reservoirs are some of the challenges faced in carrying out a successful exploration program, a task which is made more difficult due to the limited data available in the area. Different formations show wide range of thickness and facies variation and at times truncations of the entire formation towards east makes this area also attractive for stratigraphic cum structural plays.
AAPG Datapages/Search and Discovery Article #90194 © 2014 International Conference & Exhibition, Istanbul, Turkey, September 14-17, 2014