官寨井田地面煤层气抽采潜力研究

Study on CBM Surface Drainage Potential in Guanzhai Minefield,Guizhou

针对贵州官寨井田煤层气地质条件、煤储层特征,结合官寨井田地面煤层气抽采试验工程与产能预测分析,对该地区煤层气抽采潜力进行研究。结果表明:官寨井田地质和煤层储层条件相对较好,属于中等构造程度;煤层层数多、总厚度大、气含量高、渗透性相对较好,属于碎裂结构的硬煤;裂隙比较发育,资源丰富,丰度较高,有利于地面煤层气抽采;现场试验与统计显示,在为期220d的排采周期内,单井实现气产量超1000m 3/d的工业性气流,且稳产时间相对较长,具有良好的地面煤层气抽采前景;煤层气井产能预测模拟显示,连续排采15a,单井累计产气量达259.22×104 m 3,具备良好的可采性;建议后期采用以“地面垂直井+丛式井为主、地面水平井为辅”的开发模式进行滚动式开发。

In allusion to CBM geological condition,coal reservoir features in the Guanzhai minefield,Guizhou,combined with CBM surface drainage test engineering and capacity prediction analysis in the minefield have carried out CBM drainage potential study.The result has shown that geological and coal reservoir conditions are relatively better in the minefield.The minefield has medium structural complexity,multiple coal seams with large total thickness and high methane content;permeability is relatively better,coal belongs to cataclastic textured hard coal with well developed fractures,thus CBM resources are abundant and favorable to CBM surface drainage.The site tests and statistics have shown that within a 220-day drainage cycle,single well can realize 1000m 3/d excess commercial gas flow with relatively long stable production period,thus excellent CBM surface drainage prospect.The CBM well capacity prediction simulation has shown that within 15 years successive drainage,single well cumulative production can be 259.22×104 m 3,thus excellent recoverability.It is suggested that in later stage an exploitation mode of“mainly surface vertical well+cluster well complemented by surface horizontal well”should be used to carry out rolling exploitation.