Organic geochemical characters of source rock and significance for exploration of the Tumuxiuke Formation in Fuman area, Tarim Basin

Abstract

Objective As a newly discovered source rock in the Fuman area of the Tarim Basin, the source rock of the Tumuxiuke Formation has good petroleum exploration prospects, and the geochemical evaluation of the source rock is conducive to guiding exploration. Methods The qualitative and quantitative characterization of drill cuttings from the Tumuxiuke Formation in the Fuman area was carried out by means of total organic carbon (TOC) content, Rock-Eval pyrolysis, and GC-MS analysis of saturated and aromatic hydrocarbons. Results The results show that the source rock of the Tumuxiuke Formation is a good to excellentsource rock, with an average TOC content of 3.4%. The highest hydrogen index (HI) is 590 mg/g, and the kerogen type is mainly type Ⅱ. According to the molecular geochemical characteristics, the source rock was formed in a marine sedimentary environment with weakly reducing brackish water, with aquatic algae as the primary hydrocarbon-generating organisms.Based on the peak temperature (Tmax) of Rock-Eval, saturated hydrocarbon biomarker compounds, and aromatic hydrocarbon thermal maturity parameters, the source rock of the Tumuxiuke Formation is generally in the mature-medium mature evolution stage and has good hydrocarbon generation potential. Conclusion As the sedimentary center of the Huanman Depression, the southern Fuman area may have thicker and higher-quality Tumuxiuke source rock with a greater degree of thermal evolution, whose contribution to the oil and gas resources in the Ordovician cannot be ignored.

Keywords

• tarim basin
• fuman area
• tumuxiuke formation
• source rock
• organic geochemistry