The depositional evolution and controlling factors of the Lower Triassic Baikouquan Formation, Northern Mahu Slope, Junggar Basin, NW China

Abstract

Significant hydrocarbon discoveries that resulted from conglomerate reservoirs in the Baikouquan Formation have been found in the last few years in Mahu Sag, Junggar Basin. Many studies have been conducted to describe the sedimentological complexity of reservoirs. However, few of them have been focused on the depositional characteristics and associated controlling factors in Baikouquan Formation. In this study, analysis of cores, thin sections, wireline logs, and seismic volume were carried out obtain detailed descriptions and interpretations of sedimentary microfacies, depositional evolution, and associated controlling factors. The results indicate that seven sedimentary microfacies are identified in Baikouquan Formation. Furthermore, depositional evolution of fan delta systems from bottom to top of Baikouquan Formation shows retrogradation in general. Tectonic activities along the northwestern fault zone, rising lake levels, arid climate, and high temperature together exert the controls on depositional evolution of fan delta systems in Baikouquan Formation.