煤层气藏边界类型、成藏主控因素及富集区预测

如何定义煤层气藏、如何界定气藏边界是认识煤层气藏的关键，要评价煤层气富集区首先要找出控制其成藏的主要因素。为此，结合我国含煤盆地的典型煤层气藏特征，围绕煤层气藏边界类型、成藏主控因素进行了探讨，并预测了沁水、鄂尔多斯、准噶尔盆地的煤层气富集区。结论认为：①煤层气藏的边界是煤层气藏划分的前提，煤层气藏主要有5种地质边界类型：水动力边界、风氧化带边界、物性边界、断层边界和岩性边界；②煤层气藏的形成经历了煤层气的生成和吸附、煤层的吸附能力增加和煤层气的解吸-扩散和保存阶段；③保存阶段是成藏的关键，区域构造演化、水动力条件和封闭条件是主要的成藏控制因素。进而在沁水盆地、鄂尔多斯盆地和准噶尔盆地优选出9个煤层气有利富集区：晋城、阳城、安泽、阳泉、大宁-吉县、韩城、吴堡、准南、阜康。

Coalbed gas reservoirs: Boundary types, main controlling factors of gas pooling, and forecast of gas-rich areas

How to define a coalbed gas reservoir and identify its boundary is important for researchers to know well about the coalbed gas reservoirs, and a better evaluation on the coalbed gas-rich areas relies mostly on a better understanding of the main controlling factors of coalbed gas pooling. Therefore, in combination with the characteristics of typical coalbed gas reservoirs in some coal-bearing basins in China, this paper discussed the boundary types and the main controlling factors of coalbed gas reservoirs, and forecast the coalbed gas-rich areas in the Qingshui, Ordos, and Junggar basins. The conclusion was presented as follows: a. the boundary of a coalbed gas reservoir is the prerequisite of classifying the coalbed gas reservoir types, and five boundary types include hydrodynamic boundary, the boundary of efflorescent oxygenized belts, petrophysical boundary, fault boundary, and lithological boundary; b. a coalbed gas reservoir came into being after the following stages: methane gas first generated and was adsorbed in coalbed layers, then the adsorption ability of coalbed layers increased, and gas was preserved after desorption-diffusion-migration; c. the preservation stage plays an important role in a coalbed gas reservoir, and regional structure evolution, hydrodynamic and sealing conditions are the main controlling factors. Furthermore, nine optimal coalbed gas-rich areas were selected from the Qingshui, Ordos, and Junggar basins: Jincheng, Yangcheng, Anze, Yangquan, Daning-Jixian, Hancheng, Wubao, Zhunnan, Fukang.