准噶尔东南缘中低煤阶煤层气富集规律及成藏模式

准噶尔盆地东南缘煤层气资源丰富但勘探程度相对较低，富集成藏机制和主控因素认识不足，制约了勘探实践。基于对准东南地区煤层气地质条件的精细解剖，揭示了研究区煤层气富集特征及成藏机制。研究发现，准南煤系主要发育在天山山前断褶带，受构造控制明显，东西向断层和背斜密集；煤层层数多且与砂岩叠置发育；煤岩孔径较大，孔隙连通性好，煤层含气量总体上呈现西高东低的特点。在此基础上，建立了准东南地区主要发育急倾斜煤层构造-水力封堵型混合气富集成藏模式，认为“相对的高压的封闭区是煤层气富集和成藏的有利部位”。故在煤层气勘探中应优选埋深适中的“相对构造高点”和平缓的地表水与地下水稳定过渡带，并建议对阜康-大黄山有利目标区开展立体勘探实践。

Formation mechanism and enrichment patterns of middle-low rank coalbed methane in Southern Junggar Basin,China

The abundant coalbed methane exploration in the southeast margin of Junggar basin has not made a greater breakthrough for its complicated geological structure and reservoir formation mechanism.Therefore,its accumulation mechanism and main controlling factors become the most critical constraint issues for CBM exploration.On the basis of the fine dissection about geological conditions of the coalbed methane here,the characteristics of coalbed methane accumulation and the reservoir formation mechanism were revealed.The authors found that the coal seams controlled by complicated geological structure,with east-west fault and anticline,were mainly developed in the Tianshan piedmont fault fold belt.And the coal seams and sandstone were superposed.Also the high porosity of coal has good pore connectivity.As a whole,the gas content is generally high in the West and low in the East.Therefore this paper established a mixed gas source enrichment model of the structure-hydraulic plugging type in the steeply inclined coal seam.And it is concluded that the sealing zone with relatively high pressure is the favorable area for coalbed methane accumulation.So the relatively high point of the structure and the transitional zone between surface water and groundwater should be optimized in the exploration of coalbed methane.Therefore,the authors suggest to carry out stereoscopic exploration in the Fukang-Mount Huangshan favorable target area.