贵州中西部地区煤层气成藏特征

基于贵州地区煤层气富集成藏条件，结合统计资料和实验测试数据成果．从含气性、储层物性及成藏规律三个方面探讨了贵州中、西部地区煤层气藏特征。结果表明：贵州中、西部地区2000m以浅煤层气资源量约31511亿m^3，资源丰度高，一般〉2亿m^3／km^2，最高可达7．15亿m^3／km^2，主要集中分布在六盘水煤田、织纳煤田及黔北煤田煤，且以富甲烷（〉8m^3／t）为主，500m以深范围内煤层气CH4含量〉80％；不同地区不同煤层的孔裂隙发育、渗透性、吸附能力、解析能力、储层压力及储层压力系数等差别较大，地域、层域差异明显，煤储层原地应力较高，原地应力梯度普遍〉1．5MPa／100m;区内煤系地层“广覆式”生烃．沉积构造史控制着气田的分布，并以大型向斜或复向斜为煤层气富集主要场所。

CBM Reservoiring Characteristics in Central and Western Guizhou

Based on CBM enrichment and reservoiring conditions in the Guizhou area, combined with statistical data and laboratory testing results, and discussed CBM reservoir characteristics in central and western Guizhou from methane-beating property, reservoir physical property and reservoiring pattern 3 aspects. The result has demonstrated that： CBM resources above the depth 2000m in central and western Guizhou is about 3151.1 billion m^3, with high resource abundance, generally 〉 0.2 billion m^3/km^2, maximum 0.715 billion m^3/km^2. The resources are mainly distributed in the Lupanshui, Zhina and North Guizhou coalfields, mainly methane rich resources （CH4 content 〉 8m^3/t）, and above depth 500m, CH4 content 〉80%. There are larger and distinct differences in porosity, permeability, adsorptivity, desorptivity, reservoir pressure and reservoir pressure coefficient among different areas and different coal seams. In-situ geostress of coal reservoir is high, in-situ geostress gradient 〉1.5MPa/100m. Coal measures strata in the area have generated hydrocarbon extensively, sedimentary tectonics controlled the distribution of methane fields, and main CBM enrichment places are large-scale synclines and synclinoria.