Shale gas exploration potential and target of Permian Dalong Formation in northern Sichuan

Abstract

The temporal and spatial distribution characteristics and basic geological conditions of organic rich shale in the Permian Dalong Formation in northern Sichuan Basin were studied based on the comprehensive analysis of geological and geophysical data. The Dalong Formation shale reservoir in the northern Sichuan region has favorable geological conditions of "high TOC content, high porosity, high brittle mineral content, and high gas content", showing a great exploration potential. The first significant property is the development of favorable facies belts in the deep-water shelf of the Dalong Formation in the northern Sichuan, with a thickness of 20-45 m and a wide areal distribution. Secondly, the average brittle mineral content of organic rich shale in the Dalong Formation is 82.3%, the organic matter type is humic-sapropel type, the average organic carbon content is 8.32%, the average thermal evolution degree(Ro) is 2.43%, the average porosity is 3.0%, and the average total gas content is 4.62 m3/t. The third positive factor is that the study area is separated from the basin-controlled Micangshan Fault by fault depressions, and the preservation conditions in the direction of the basin are good. It is proposed that the deep-water shelf facies of the organic-rich mud shale of the Dalong Formation in Nanjiang area is well-preserved, and the burial depth is moderate (2 000-5 000 m). It is a most favorable area for exploration in the near future.

Keywords

• shale gas
• exploration direction
• dalong formation
• permian
• northern sichuan area