Controlling effect of reservoir-cap combination quality on richment grade of biogas in Sanhu area of the Qaidam Basin
Cheng Fuqi1, Jin Qiang2, Lin Huixi1, Zhang Shuichang3, Su Aiguo3, Cao Qian2, Wang Li2
1. Institute of Geological Science, Shengli Oilfield Branch Company, China Petroleum and Chemical Corp., Dongying, Shandong 257015; 2. College of Earth Resources and Information, China University of Petroleum, Dongying, Shandong 257061; 3. Research Institute of Petroleum Exploration and Development of China, Beijing 100083
Sanhu area in eastern part of the Qaidam Basin is rich of biogas, but its distribution in the area is hetero-equilibrium not only in different tectonic locations but also in different reservoir-cap combinations of same biogas field. In order to find the controlling effect of reservoir-cap combination quality on distribution feature and rich grade of biogas in the area, displacement pressure differences and biogas diffusion ratios of all reservoir-cap combinations of biogas fields found there were calculated out, and then relationships of displacement pressure differences, biogas diffusion ratios, biogas reserves and unit reserves coefficient were investigated. According to the results, only the reservoir-cap combinations which had great displacement pressure differences were rich in biogas, and correspondingly, those with small displacement pressure differences could not be rich in biogas. On the other hand, reservoir-cap combinations with great diffusion ratios had small reserves and lower unit reserves coefficients, and those with small diffusion ratios always were high rich in biogas. Because the displacement pressure difference and biogas diffusion ratio represented quality of reservoir-cap combination, the relationships between the both parameters and biogas richment grades reflected controlling effect of reservoir-cap combination quality on distribution features and richment grades of biogas in Sanhu area.
Cheng Fuqi,Jin Qiang,Lin Huixi et al. Controlling effect of reservoir-cap combination quality on richment grade of biogas in Sanhu area of the Qaidam Basin[J]. Chinese Journal of Geology, 2008, (2): 333-346.