SOURCE ROCK EVALUATION OF RANIKOT FORMATION IN SAWAN-01, MIDDLE INDUS BASIN, PAKISTAN

Abstract

Understanding source rock and its related petroleum system is of critical importance in hydrocarbon prospecting. Organic matter quantity, quality and maturity studies have been carried out on shales of Ranikot Formation in Sawan-01, located in Middle Indus Basin. The formation was investigated using total organic carbon (TOC) and Rock-Eval pyrolysis analyses measurements. Analyses were performed on five well cutting samples from well, having TOC 0.16-2.28 wt. % representing poor to very good source rock potential. The Genetic potential (GP) values of the samples lies between 0.12 to 2.81mg HC/g rock, depicting poor to fair source rock potential. HI values are in between 65-112 mg HC/g indicating presence of type III kerogen with gas generation phase. Type of organic Matter evaluation using hydrogen and oxygen indices also show that samples are predominantly of kerogen type III (gas prone) in origin. Tmax values ranges from 446 to 452oC which indicate that samples predominantly lie in peak to onset of late thermally mature region. Weathering/oxidation effect is greater in lower part of formation represented by high oxidation index values. Organic matter supply was good at the time of deposition of Ranikot Formation but lower part of this formation was deposited in oxic environment and lead to poor preservation which is confirmed by decreasing trend of organic richness against depth. Hence, it can be concluded that upper shales of Ranikot Formation got enough organic matter richness and maturity to produce gas in study area.