Geochemical characteristics and shale oil exploration potential of the Da’anzhai Member in the Sichuan Basin, southwest China

Abstract

Based on the analysis of the organic geochemical characteristics of the shale in the Da’anzhai Member in the Sichuan Basin, southwest China, we discuss the hydrocarbon generation potential, hydrocarbon expulsion efficiency ( EH), and oil-bearing properties to identify the dominant exploration direction for shale oil. The results indicate that: (1) the Da’anzhai shale has low organic matter content and high maturity with the average total organic carbon (TOC) content of 1.27% and average vitrinite reflectance (Ro) of 1.29%, (2) the EH of the Da’anzhai shale ranges from 0% to 92% with an average value of 72%, (3) the lower limit of TOC for shale commercial production is 1.5%, which is lower than any current standard in China and North America, and (4) shale oil in the center lacustrine basin is more enriched compared with the outskirts of the basin with [Formula: see text], Ro < 1.25%, EH < 67%, and oil saturation index > 100 mg/(g·TOC). These results indicate that the prospects for shale oil exploration in the central basin are optimistic and should be the key exploration area for shale oil in the future.