Petroleum Potentiality and Petrophysical Evaluation of Late Triassic Baluti Formation, Northern Iraq

Abstract

Source rock potentiality and reservoir characteristics of the Baluti Formation (Late Triassic), Northern Iraq were examined in order to determine the hydrocarbon generation potential and reservoir properties. A combination of geochemical analyses, stable carbon isotope, 1D-basin modeling and digital log data were used to evaluate the formation. The Total Organic Carbon ratios range from 0.39 to 0.61 wt%, while the quantity of free hydrocarbon and residual hydrocarbon are low (0.05-0.11, 0.40-0.90 mg/g respectively). The average of oxygen index is 318 mg CO2/g TOC, while the hydrogen index is less than 200 mg HC/g TOC, which indicates type III kerogen. The outcomes of the pristane/phytane and Pr/n-C17 with Ph/n-C18 ratios suggest that the formation was deposited under oxic environment. This conclusion is also supported by trace elemental data. According to the average of Ro% of 0.58 and Tmax of 430.1oC, the formation is in immature to early mature stage. From a plot of 1D-modeled Ro% versus time, it is inferred that the organic matter of the formation had reached early maturation in the Early Paleocene (63Ma). The Baluti is waxier formation and the degree of waxiness ranges from 1.99-2.55. Regarding to, Triterpanes (Tm/Ts) and regular sterane C27-C29 the studied formation has deposited in terrestrial environment with high terrigenous input with hot and arid to semiarid climates. This result is supported by stable carbon isotopic data and clay mineralogy. Porosity of the dolomite beds is 10-15%. Based on the cutoff results, the Baluti Formation has only 1.13m net pay of 72m thickness, which means that the formation has poor porosity and permeability in the reservoir beds.