Accumulation patterns of low-rank coalbed methane gas in the Jiergalangtu Sag of the Erlian Basin

被引：0
|
作者：
Sun Q. [1 ,2 ]
Wang S. [1 ]
Tian W. [2 ]
Sun B. [2 ]
Chen Y. [3 ]
Yang Q. [2 ]
Chen H. [2 ]
Yang M. [2 ]
Qi L. [2 ]
机构：
[1] China University of Geosciences-Wuhan, Wuhan, 430074, Hubei
[2] PetroChina Research Institute of Petroleum Exploration & Development, Langfang, 065007, Hebei
[3] PetroChina Huabei Oilfield Company, Renqiu, 062552, Hebei
来源：
Natural Gas Industry | 2018年 / 38卷 / 04期
关键词：
Accumulation pattern; Biogas; Coalbed methane (CBM); Erlian Basin; Fault basin; Favorable area; Jiergalangtu Sag; Low-rank coal; Sealed by confined water;
D O I：
10.3787/j.issn.1000-0976.2018.04.007
中图分类号：
学科分类号：
摘要：
The Erlian Basin is a typical low-rank lignite distribution area in China. Its coalbed methane (CBM) resources are abundant, but the CBM enrichment and accumulation mechanisms are not understood sufficiently, which restricts the exploration and development of low-rank CBM gas. In this paper, with low-rank CBM gas reservoirs in the Jiergalangtu Sag of the Erlian Basin as an example, the main factors controlling CBM accumulation were analyzed from the aspects of coal bed distribution, gas content, CBM origin, biogenic gas simulation experiment and preservation conditions, and then the future exploration direction was pointed out. Some results were obtained. First, a thick coal bed is developed at the central belt-gentle slope of the Jiergalangtu Sag in the coal forming environment of shallow lake basins, and it compensates for the deficiency of gas content. Second, mudstones overlying coal beds are developed periodically due to the periodic occurrence of shallow lake during the accumulation of coal bearing sections, so the caprocks are favorable. Third, the central belt-gentle slope of the Jiergalangtu Sag is located in a confined groundwater area, where the hydraulic lateral sealing is favorable for CBM accumulation. Fourth, CBM in the study area is biogenic with an in-situ gas production ratio of 0.25 mL/g, and currently the generation of biogenic gas still continues. Fifth, the CBM enrichment pattern in the fault basin is that biogas and CBM gas are both sealed by confined water. It is concluded that the key factors for CBM accumulation in the Jiergalangtu Sag are thick coal beds, biogas generation, favorable seals/caprocks and hydraulic confined areas. Besides, the Well L12-S88 area in the central belt-gentle slope of the Jiergalangtu Sag is the favorable area for future CBM productivity construction. © 2018, Natural Gas Industry Journal Agency. All right reserved.
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页码：59 / 66
页数：7
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