Characteristics and controlling factors of the organic-rich shale in the Wujiaping Formation of the Hongxing area, eastern Sichuan Basin

Abstract

Objective The organic-rich shale of the Upper Permian Wujiaping Formation in the Hongxing area of eastern Sichuan is an important replacement area for shale gas exploration in the Sichuan Basin, and the exploration breakthroughs have been made. But how to achieve large-scale storage increase and efficient development needs to be tackled. Methods This paper investigates the source and reservoir quality characteristics of the shale of the Wujiaping Formation in the Hongxing area of eastern Sichuan based on lithological, geochemical and gas-bearing test and analysis data and discusses the factors controlling the development of high-quality reservoirs. Results The results show that the shale of the Wujiaping Formation has a good organic matter type, dominated by type Ⅱ1 kerogen, with high TOC content, high carbonate content and high gas content. The shale TOC content generally ranges from 1% to 11%, with an average value of 6.89%; the lithology is mainly siliceous shale and mixed shale, followed by calcareous shale, and the overall brittle mineral content is high; the reservoir organic matter pores are developed and have good physical properties, and the porosity generally ranges from 2% to 5%, with an average value of 3.1%. Comprehensive analysis shows that the high-quality reservoir of the Wujiaping Formation is strictly controlled by the depositional environment. The reservoir pore type is dominated by organic pores. Conclusion Under the control of this depositional model, sea level rise and fall, volcanic activity and palaeoclimate have jointly controlled the inhomogeneity and high-quality shale reservior distribution.

Keywords

• organic-rich shale
• control factor
• wujiaping formation
• hongxing area
• sichuan basin