Source Rock Potential of Oil Shale Deposits in Kohat Basin, Pakistan

Abstract

Jatta Gypsum in Kohat basin (Kohat and Karak districts, North Western Frontier Province) contains oil shale horizon at six widely scattered localities. Generally, the oil shale horizon occurs at about 27 to 30m below the top of Jatta Gypsum. The thickness of the oil shale is 0.5 to 1.5m with total organic carbon (TOC) upto 25% and oil-yield 20%.
Another oil shale horizon with average TOCupto 13% has been located in Nikki Pail area, west of the main oil shale occurrences, in a transitional zone at the top of Kuldana Formation.
The average composition of most of these shale occurrences is much above the critical limit of TOCfor classifying them as oil shale. However their limited lateral extent and thickness are constraints in their economic exploitation as oil shale. They may act as excellent potential source rocks if present at depth with lateral continuity.
Besides oil shale, oil impregnated rocks and oil seeps have also been reported from the area.