晋中盆地西南缘煤层气地质特征及资源潜力研究

CBM Geological Features and Resource Potential in Southwestern Margin of Jinzhong Basin

在分析煤层构造演化特征、沉积环境及岩性岩相特征、空间展布特征、煤岩煤质特征及含气性的基础上,评价了晋中盆地西南缘煤层气资源勘探潜力,并优选了有利区。研究结果表明:研究区主力煤层镜质体反射率(R o)在0.94%~1.32%,主要为焦煤;煤层埋深较大,3号煤为700~1800m,9号煤为800~1900m;厚度适中,3号煤为0.0~1.91m,平均1.61m,10+11号煤为1.5~6.5m,平均4.8m。通过Langmuir方程建立的煤层含气量计算模型预测含气量中等较高,3号煤为7.07~11.19m^3/t,平均9.67m^3/t,10+11号煤为7.84~12.57m^3/t,平均10.97m^3/t。煤层位于构造稳定带,埋深越大、厚度越大、顶底板岩性越致密及厚度越大,煤层含气量越高,含气量分布主要受控于构造样式和煤层埋深。并通过建立区块煤层气有利区优选标准,优选出3号煤有利区3处,10+11号煤有利区5处。

Based on analyses of coal reservoir structural evolution,sedimentary environment,lithology,lithofacies,spatial distribution,coal petrology,coal quality features and gas-bearing property have assessed CBM resource exploration potential in the southwestern margin of Jinzhong Basin,and optimized favorable areas.The study has shown that the main coal seam vitrinite reflectance(R o)is 0.94%~1.32%,thus mainly coking coal.Coal reservoir buried depth is rather deep:coal No.3700~1800m;coal No.9800~1900m;with medium thickness:coal No.30.0~1.91m,average 1.61m,coal No.10+111.5~6.5m,average 4.8m.Through Langmuir equation established coal gas content computation model has predicted gas content belongs medium to rather high:coal No.37.07~11.19m^3/t,average 9.67m^3/t,coal No.10+117.84~12.57m^3/t average 10.97m^3/t.Coal seams are situated in structurally stable zone,the deeper the buried depth,the thicker the coal thickness;roof and floor lithology the compacter and thicker,the higher the coal gas content;gas content distributions mainly controlled by structural pattern and coal buried depth.Through block CBM favorable area optimization criterion establishment has optimized coal No.3 favorable areas 3,coal No.10+11 favorable areas 5.