SOURCE ROCK EVALUATION OF DATTA FORMATION, TOOT-02, POTWAR SUB-BASIN, PAKISTAN

Abstract

Organic matter quantity, quality and maturity studies have been carried out on the shale of Datta Formation in Toot-02, located in Potwar sub-Basin. The formation was investigated using total organic carbon (TOC) and Rock-Eval pyrolysis analyses measurements. Analyses were performed on six well cutting samples from well, having TOC 0.51-1.12 wt. % representing fair to good source rock potential. The S2 values of the sample shows poor to fair generative potential which lies between 0.18 to 5.55 mg HC/g rock. HI values are generally low 31.6-96.2 mg HC/g except for one sample which reached 496 mg HC/g indicating oil generation phase. Type of organic Matter evaluation using hydrogen and oxygen indices shows that samples are predominantly kerogen type III with one sample having kerogen type II. Weathering/oxidation effect is greater in upper part and this trend decreases with depth which indicates suboxic to oxic environment of deposition. Tmax values ranges from 299 to 428°C indicating immature source rock except one sample which entered in maturity window zone with Tmax of 450°C. Maturity studies depict formation status as immature in upper part with low level of convertibility to hydrocarbons while in lower part (one sample) is mature enough to produce oil.