Exploration prospect of shale gas with Permian transitional facies of some key areas in China

Abstract

The shale gas exploration of marine-continental transitional facies in China has not yet gained a significant success. To analyze and predict the exploration prospect of transitional shale gas, the distribution, organic geochemical and reservoir characteristics of transitional shale in some key areas of China were compared. The transitional shale is widely distributed in China and is characterized by the thin thickness of single layer and the rapid variation of lithology. The kerogens of transitional shale are mainly of type Ⅲ. Except for carbonaceous mudstone, the total organic content is generally low, and the hydrocarbon generation potential is the lowest. The dominant pore types of transitional shale are inorganic pores and micro-fractures, while the organic pores on the other hand were not developed. The pore volume and pore specific surface area of transitional shale are lower than those of marine shale, the reservoir space is relatively insufficient, and the gas adsorption capacity is poor. Transitional shale has a remarkable high content of clay minerals, less brittle minerals, low porosity and permeability, and poor reservoir physical properties indicating unconducive for the late-stage development. Results show that marine shale is still the most favorable area for shale gas exploration, and the exploration prospect of shale gas in transitional facies may not be regarded as good as that of continental shale gas which has a higher thermal mature degree in some aspects.

Keywords

• mud shale
• shale gas
• marine-continental transitional face
• exploration prospect
• china