Geochemical Analysis Of Lockhart Limestone For Hydrocarbon Potential In Kotal Section, Kohat Basin, Khyber Pakhtunkhwa, Pakistan

Abstract

The present research is based on source rock evaluation of Lockhart Limestone. The field was done to the well-exposed section in Kohat Ranges near Dara Adam Khel. A total of 13 samples were collected randomly and upon those samples, geochemical analysis and petrographic analysis were done. Geochemical analysis includes TOC and rock eval pyrolysis, TOC of the samples were S1- 0.32, S2- 0.30, S3- 0.28, S4- 0.30, S5- 0.23, S6- 0.43, S7- 0.26, S8- 0.32, S9- 0.22, S10- 0.26, S11- 0.28, S12- 0.24, S13- 0.20 respectively. Only five samples were qualified (S1, S2, S4, S6 and S8) for rock eval pyrolysis having S1 values of 0.02, 0.02, 0.02, 0.04, and 0.01 respectively. S2 values of 0.06, 0.04, 0.03, 0.12, and 0.03 accordingly. Similarly, the value of S3 is 0, 0, 0, 0.06, and 0. Whereas the values of Tmax (°c) are 474, 324, 483, 446, and 483. The kerogen type is type II & type III, and most of them lie in the dry gas window having transitional between anoxic & terrestrial environment. In the petrographic analysis 13 thin sections were studied and different diagenetic features and fossils were discovered, fossils include Lockhart, Lockhart email, Lockhart condition, rosalia, Plano-rotalite, planorotalite pseudomorphs, bryozoans, algal filaments, small & large benthic forams, bivalves, gastropods, miscellanea miscella, miliolid, adularia, and broken bioclastic fragments in bioclastic wackestone, packstone, mudstone, and wackestone-packstone facies. From the above results, it concluded that Lockhart Limestone is a poor source rock.