Organic Geochemistry and Thermal History Modeling of the Upper Part of Kurra Chine Formation (Upper Triassic) from Butmah-15 Well, Northwestern Iraq

The potentiality of the upper part of the Kurra Chine Formation (Late Triassic) for hydrocarbon generation in northern Iraq was assessed using data from the Butmah-15 well. Total organic carbon (TOC) and Rock-Eval pyrolysis analyses were conducted on nine rock samples; biomarker analysis was carried out for two samples, after extraction of the bitumen, to determine the paleodepositional environment conditions. The examined interval has low TOC values (< 0.5 wt.%) and limited potential for hydrocarbon generation. Thermal history modeling results suggest that the high TOC intervals in the lower part started oil generation from the Middle Jurassic (~170 Ma) to the end of the Early Cretaceous (~ 100 Ma), and reached the end of the oil window at the end of the Miocene. Maturity parameter values (biomarkers and Tmax) indicate early to mid-mature organic matter. Normal alkane distribution shows the dominance of short chains over long chains and suggests that the organic matter is mainly of marine origin. C35S/C34S and Pr/Ph ratios suggest that the examined interval was deposited under low oxygen conditions (suboxic-anoxic).