An analysis of reservoir conditions and geochemical characteristics of the Triassic shale gas in Qilian region, Qinghai Province

Triassic strata with dark shale and carbonate rocks are widely distributed in Qilian region of Qinghai Province. In this paper, the route geology was surveyed, drilling was conducted, samples from North Qilian and Muli areas were analyzed, and data collected from south Qilian basin and north Qilian basin were collected. The results show that the thickness of Triassic is large. Most of the organic matters belong to low-medium abundance, with a small part belonging to relatively high-high abundance. The types of organic matters are mainly typeⅡ₁ andⅡ₂, with a small part being typeⅢ. The maturity of organic matters have reached low mature-mature stage, within the maturity range favorable for the shale gas generation. The values of quartz, plagioclase mineral calcite and other brittle minerals of dark shale are relatively high. The space types of shale reservoirs mainly include two types of pores and cracks. In brief, Qilian Triassic shale shows good conditions for hydrocarbon source and has good exploration prospect.