Characteristics and main controlling factors of organic pore development in continental shales of the Lianggaoshan Formation in the Fuxing area, Sichuan Basin

Abstract

The Lianggaoshan Formation in the Fuxing area of the Sichuan Basin has developed a typical set of medium to high maturity continental shale condensate oil reservoirs. Research on the development characteristics and patterns of organic pores in shale reservoirs at the condensate oil stage is relatively sparse. Using experimental methods such as whole-rock thin section organic petrography identification, argon ion polishing-scanning electron microscopy observation, and energy spectrum measurement, this study analyzed the characteristics and main controlling factors of organic pore development in the Lianggaoshan Formation shales in the Fuxing area. The research results showed that, at the high maturity evolution stage (Ro=1.30%), organic pores developed within the primary organic matter and solid bitumen in the continental shales of the Lianggaoshan Formation. The organic pores were mainly nanopores with irregular shapes, exhibiting honeycomb-like clusters, which locally connected to form micron-sized pores or micro fractures. The type of organic maceral was the basis for organic pore development in the Lianggaoshan Formation shales. Relatively high organic matter abundance and thermal evolutiondegree were key factors controlling the development of organic pores. The inorganic mineral framework and the diagenetic-hydrocarbon generation evolution process were the ultimate guarantees for the preservation of organic pores.

Keywords

• organic pore
• primary controlling factor
• continental shale
• lianggaoshan formation
• middle jurassic
• fuxing area
• sichuan basin