黔北煤田长岗向斜煤层气富集的构造控制作用

Structural control on the enrichment of CBM in Changgang syncline, northern Guizhou coalfield

根据黔北煤田长岗向斜的煤田地质钻孔及相关测试资料,分析了构造作用对该区煤层气富集的影响。研究表明,长岗向斜轴部为主要的煤层气富集有利区,煤层甲烷含量在20 m^3/t以上,且总体表现为由向斜轴部到平缓翼再到边浅部陡坡带,煤层气含量逐渐降低;同时向斜轴部转折部位构造应力相对复杂,以张性应力为主,导致煤层甲烷含量较低,为20 m3/t以下,此外,该区发育的正断层同样造成煤层甲烷逸散,最低为10 m^3/t左右。由断层带至断层两侧,甲烷含量逐渐上升。构造作用对煤层气富集的影响可为长岗向斜煤层气进一步的勘探开发提供基础依据。

The coal seam of Changgang syncline has the characteristics of many layers of coal seam,thin single layer,but the high gas content.The existing CBM w ells show that the area has a certain potential for CBM exploration and development.However,the study on the enrichment of CBM is blank in the aera.Based on the data of coal geology,drilling and related test data of Changgang syncline,a brief analysis of the coalbed methane accumulation in this area have been made.The influence of tectonic action on coalbed gas enrichment in this area is analyzed.It can provide a certain direction for further exploration and development of CBM in Changgang syncline.Changgang syncline axis is favorable area for CBM enrichment,and the content of CBM is over 20 m 3/t.The gas content in axial part of the syncline is high,and lower in the syncline wings.And the turning parts of synclinal axis also have lower gas content.In addition,the normal fault can cause the dissipation of CBM.The low est CBM content is about 10 m 3/t.The pressure fault has little effect on it.