SOURCE ROCK EVALUATION OF SEMBAR FORMATION, SOUTHERN INDUS BASIN, PAKISTAN

Abstract

It is vital to understand the source and its relative petroleum system in the hydrocarbon prospecting. The organic matter quality, quantity, and maturity analyses have been carried out on shales of Sembar Formation (Well-X) located in the Southern Indus Basin. The concerned Formation was investigated using total organic carbon (TOC) and Rock-Eval pyrolysis analysis. Seven well cuttings of Well-X were used, having TOC values ranging from 0.75 to 1.26 wt. %, which indicates fair to good source rock potential. The Genetic Potential (GP) values range from 0.42 to 1.55mg HC/g rock, which shows poor source rock potential. The HI values range from 24 to 86 mg HC/g indicating the presence of type III kerogen with gas generation phase and type IV kerogen. Organic matter evaluation by using the hydrogen and oxygen indices shows that the samples are mostly of type III kerogen in origin and are gas prone. The values are from 425°C to 436°C, and it indicates that the samples lie in immature to Early mature source rock region. Based on the above source rock characteristics of Sembar Formation, it can be concluded that Sembar Formation got favorable organic richness along with maturity and likely to produce gas in the study area, especially in the deeper parts of the basin.