Elementary Factors and Their Configuration of BiogasAccumulation in Eastern Qaidam Basin
柴达木盆地三湖地区生物气成藏基本要素及其配置性

Sanhu area in east Qaidam basin is the Quaternary sedimentary center in the Qaidam basin and the biggest biogas production area in China, has an average surface altitude of around 2800 m, and locates in the northern segment of the Qinghai\|Tibet Plateau. The Quaternary system, which mainly consists of weak consolidated sandstone and mudstone, has a thickness of more than 3400 meters. The condition of low temperature and high salinity provides a material foundation for the formation of biogas, the sand\|shale sequences provide adequate reservoir and caprock conditions for biogas accumulation, the synsedimentary anticlines provide biogas traps, and the subsurface directional flow water connects the source of biogas with reservoirs and traps and makes a dynamic balance of biogas accumulation\|leakage. The promising regions for Quaternary biogas accumulation and location should meet all the following requirements: adequate biogas source, long time traps, good mothballing conditions and their good association. The Sebei and Tainan areas in the north slope of the Sanhu area are favorable direction of gas migration and should be regarded as targets of next exploration.