Hydrocarbon Generation Potential of Chia Gara Formation in Three Selected Wells, Northern Iraq

Abstract

In this study collected samples of Chia Gara Formation in Atrush, Shaikhan and Sarsang oilfields are used to geochemical characteristics of organic matter in this formation. This determination was based on Rock-Eval pyrolysis and Biomarker analyses. The Chia Gara Formation can be considered as good to excellent source rock; it’s TOC content ranges from 1.14-8.5wt% with an average of 1.85%, 3.91%, and 6.94% in Atush-1, Mangesh-1 and Shaikhan-8 wells respectively. The samples of Chia Gara Formation contain kerogen type II. These properties are considered optimal for oil generation. The low oxygen index (OI) and pristane/phytane (Pr/Ph) ratios (Average 20.73, 0.61 respectively) and high hydrogen index (HI) (average 637.6) indicate that the formation was deposited under anoxic condition. According to regular sterane (C27%, C28%, C29%) and terpanes ratios (C29/C30, C31/C30 hopane), the formation was deposited in marine environment. The average value of the Carbon Preference Index (CPI) is one with Tmax values of more than 430 ºC; these indicate peak oil window for the selected samples. Overall, the 20S/(20S+20R), ββ/(ββ+αα)C29 steranes and 22R/(22R+22S)C32homohopane, with Ts/ (Ts+Tm), and moretane/ hopane ratios point to a mature organic matter and to the ability of the formation to generate oil.

Biostratigraphy of Lower Cretaceous from Selected Borehole in central Iraq

“…[19] examined the Lower Sarmord biostratigraphy in well kirkuk-109 and identified the biostratigraphic zones. In the study of [20] found that the petrophysical characteristics of Sarmord Formation in northern Iraq are made up of limestone and dolomitic limestone and have a long history of good porosity. [21] Examined the stratigraphy and nannofossi biozonation of Sarmord Formation in northern Iraq and conclude that it dates from the Late Valanginian -Barremian.…”