Dynamic Accumulation of the Quaternary Shale Biogas in Sanhu Area of the Qaidam Basin, China

Biogas resources in Sanhu area of Qaidam Basin have great potential, but there are few researches on biogas of shale, especially on the accumulation conditions of shale biogas. The study of biogas accumulation conditions of quaternary shale in Sanhu area is of great significance to the theory of biogas accumulation and the guidance of exploration and development. This paper takes the quaternary shale in Sanhu area as the research object, through the experiment of soluble organic carbon analysis, pore permeability analysis and so on, analyzes the accumulation conditions of shale biological gas reservoir from the perspectives of hydrocarbon generation, reservoir conditions, hydrodynamic and structural conditions. The results show that the quaternary shale has high soluble organic carbon content and high salinity formation water, which is conducive to the late methane biochemical generation. Quaternary shale has the characteristics of high porosity and low permeability, mainly developing intergranular pores and intragranular pores. The large pore volume and specific surface area provide a lot of storage space for free gas and adsorbed gas, and the reservoir conditions are good. Under the structural characteristics of high in the south and low in the north and the action of formation hydrodynamics, biogas migrated from the south and deep to the north of the basin. The north slope is the main biogas rich zone. On the whole, the quaternary shale in Sanhu area has the characteristics of continuous hydrocarbon generation and dynamic accumulation, which has huge resource potential and exploration and development value.