Controlling Factors on CBM Accumulation in Low-Rank Coal in Santanghu Basin

摘要/Abstract

摘要： Industrial CBM (coalbed methane) flow has been obtained from the low-rank coal in the Malang sag, Santanghu basin. However, CBM accumulation there has been less researched. In order to get more understandings to guide future exploration, we studied the CBM geological characteristics through drilling and laboratory data analysis. The results show that the coal seams in the study area have large thickness, good coal structure, relatively high gas content, and good physical properties and enrichment conditions. By combining the hydrogeological characteristics with preservation conditions, it is concluded that the CBM in the low-rank coal belongs to a mixed genetic type. Water from melted snow and rain flowing along the slope of the basin margin provides good conditions for generating biogas and plays the role of a lateral seal; and at the same time, thermogenic gas generated continuously with structural subsidence accumulates in the favorable zone on the slope, which established a mixed genetic model of CBM accumulating in the low-rank coal on the basin margin. To sum up, a good configuration of hydrogeological and structural conditions with top and bottom sealing abilities controls the CBM accumulation in the low-rank coal in the basin.

关键词: Santanghu basin, Malang sag, CBM in low-rank coal, geological characteristics, CBM genesis, preservation condition, reservoir-forming model, controlling factor

Abstract: Industrial CBM (coalbed methane) flow has been obtained from the low-rank coal in the Malang sag, Santanghu basin. However, CBM accumulation there has been less researched. In order to get more understandings to guide future exploration, we studied the CBM geological characteristics through drilling and laboratory data analysis. The results show that the coal seams in the study area have large thickness, good coal structure, relatively high gas content, and good physical properties and enrichment conditions. By combining the hydrogeological characteristics with preservation conditions, it is concluded that the CBM in the low-rank coal belongs to a mixed genetic type. Water from melted snow and rain flowing along the slope of the basin margin provides good conditions for generating biogas and plays the role of a lateral seal; and at the same time, thermogenic gas generated continuously with structural subsidence accumulates in the favorable zone on the slope, which established a mixed genetic model of CBM accumulating in the low-rank coal on the basin margin. To sum up, a good configuration of hydrogeological and structural conditions with top and bottom sealing abilities controls the CBM accumulation in the low-rank coal in the basin.

Key words: Santanghu basin, Malang sag, CBM in low-rank coal, geological characteristics, CBM genesis, preservation condition, reservoir-forming model, controlling factor

TU Zhimin, WANG Xinggang, CHE Yanqian, ZHANG Shizhao, LI Peng, CAO Zhixiong. Controlling Factors on CBM Accumulation in Low-Rank Coal in Santanghu Basin[J]. 新疆石油地质, 2021, 42(zk(English)): 57-63.

TU Zhimin, WANG Xinggang, CHE Yanqian, ZHANG Shizhao, LI Peng, CAO Zhixiong. Controlling Factors on CBM Accumulation in Low-Rank Coal in Santanghu Basin[J]. Xinjiang Petroleum Geology, 2021, 42(zk(English)): 57-63.

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