Sedimentology, Palynofacies, and Hydrocarbon Potential of the Early Cretaceous Sarmord Formation from Khabbaz and Kirkuk Oil Fields, Northern Iraq

Abstract

The Early Cretaceous Sarmord Formation of northern Iraq has been studied from two subsurface sections, Kirkuk Oil Field (well K-229) and Khabbaz Oil Field (well KH-14), through petrographic, palynolofacies and organic geochemical analyses. The study reveals presence of two groups of microfacies settings. The first is the inner ramp, and the second represents the middle to outer ramp setting. The palynofacies study indicates that the amorphous organic matter is the predominant components (87-96%), followed by phytoclasts (3-11%) and palynomorphs (0-3 %). One main palynofacies type has been identified, which includes three secondary palynofacies types (PF1 A, PF1B, and PF1C) and refers to suboxic to anoxic basin condition. Thermal alteration index measured for the KH-14 well, indicated an immature to mature (TAI= 2, +2, 3) level, while, for the K-229 well mostly immature (TAI= -2, 2). The Rock-Eval analysis indicates that the TOC wt.% content of the samples range between 0.11% and 0.82% (average 0.29%) and 0.17% and 0.56% (average 0.35%) for K-229 well and KH-14 well, respectively. The Tmax values show that the most of analyzed samples of the both sections located in the immature zone, while the few samples from K-229 refer to mature zone. Another immature stage evidence is the shape of pyrograms with minor S1 and the large S2 peak, Tmax value less than 435°C, and PI around 1.0; all these criteria support the immature stage for these rock samples.