Hydrocarbon Generative Potential of Cretaceous and Jurassic Deposits in the Ahmedpur East Oilfield Subsurface, Punjab Platform, Pakistan

Abstract

Cretaceous and Jurassic deposits in the sub-surface of Ahmedpur East Oilfield, Punjab Platform, Pakistan, have been geochemically analysed. Source rock potential of three formations namely Mughal Kot and Goru (Cretaceous) and Samana Suk (Jurassic) located in Middle Indus Basin have been investigated. The formations were investigated using total organic carbon and Rock-Eval pyrolysis analysis measurements. Analysis were performed on fourteen samples from wells, having TOC 0.57–1.65 wt.%, the S2 values of the sample shows poor to fair generative potential and lies between 0.25–2.59 mg HC/g rock, HI values are generally low 37–150 mg HC/g TOC and Tmax values ranges from 417–453 °C. The analysis shows Mughal Kot and Samana Suk formations samples have entered maturity window zone, however Goru Formation samples lies in immature zones, shown by hydrogen index vs Tmax plot. The samples from Mughal Kot and Goru formations have kerogen type III with poor generative potential, however Samana Suk Formation have fair generative potential having kerogen type III indicated by S2 vs TOC plot, hence from the results some minor gas could be expected to have been generated by Samana Suk Formation. Targeting these formations as a source rock to expel hydrocarbons involves high risk and exploration of such reserves may not be beneficial in terms of economic value.