Geological and geochemical characteristics of marine-continental transitional shale from the Lower Permian Taiyuan Formation, Taikang Uplift, southern North China Basin

摘要

In recent years, extensive studies have been conducted on conventional shale gas resources, but little work has been performed on the resource potential of marine-continental shales. This paper takes the Lower Permian Taiyuan shale in the Taikang Uplift of the southern North China Basin as an example to characterize a transitional shale reservoir. The results indicate that the Taiyuan shale has high TOC values (averaging 2.67%) and contains type III gas-prone organic matter; the shale has high R-o values (averaging 3.44%), and T-max ranges from 424 degrees C to 601 degrees C. With respect to fracability or brittleness, the content of brittle minerals in the Taiyuan shale ranges from 21% to 71% (averaging 45.55%), and the average content of clay minerals is 44.1%. Based on SEM and SEM with Ar-ion milling observation, interparticle pores, intraparticle pores, and microfractures are developed in the Taiyuan shale, which can provide reservoir space for the accumulation of shale gas. Organic matter pores rarely appear due to the organic type and high maturity. The results of this study can guide the shale gas exploration of Taiyuan Formation in the Taikang Uplift of the southern North China Basin.