构造煤分布的地质控制及其地震地质一体化预测方法--以沁水盆地阳泉新景矿3号煤层研究为例

Geological control of tectonic coal distribution and its integrated seismic geological prediction method:A case study of No.3 coal seam in Xinjing Mine,Yangquan,Qinshui Basin

构造煤与瓦斯及煤层气密切相关。由于构造煤分布具有强烈的非均质性,现有基于地质预测与地球物理直接识别的构造煤分布预测成果难以满足煤矿瓦斯超前治理及煤层气开发的精度要求。以沁水盆地阳泉新景矿3号煤层为例,利用区内钻孔煤芯数据、采掘巷道中煤体结构的连续观测数据以及三维地震成果资料,研究煤层中“软煤”(碎粒煤和糜棱煤)的分布特征,交会分析其与煤层赋存形态、断裂系统、聚煤前后地层层序砂地比、煤层厚度等地质特征参数的关系,厘清构造煤发育的主控地质要素,得出构造煤分布受构造围岩煤层“三元”突变耦合控制的认识。在此基础上,提取三维地震数据及解释成果中对构造煤分布具有主控作用的3类共6种地震地质表征属性,采用灰色关联法构建基于多属性融合的构造煤分布预测模型,预测研究区3号煤层中的“软煤”分布情况,经采掘及后续煤层气开发井验证,预测精度较高,证明了该方法的有效性及可行性,为精准预测构造煤分布提供了一种新的技术思路与方法。

Tectonic coal is highly correlated with gas and coalbed methane(CBM).Owing to its significant heterogeneity,the existing techniques used for predicting tectonic coal distribution,based on geological prediction and direct geophysical identification,do not meet the accuracy requirements in the context of coal mine gas pre-management and CBM development.We used practical data collected from the No.3 coal seam of the Yangquan Xinjing Mine in the Qinshui Basin for this study.Using the drill core data,the continuous observation of coal structure in excavated roadways,and the three-dimensional seismic results,we studied the distribution characteristics of soft coal in the coal seams.We analyzed the relationship between the distribution characteristics and other geological parameters,such as CBM occurrence,fracture system,sequence stratigraphic sandstone ratio before and after coal accumulation,and coal seam thickness.We also clarified the primary geological factors controlling tectonic coal development.In addition,we propose that the distribution of tectonic coal is controlled by the ternary coupling of abrupt changes in tectonics,peripheral rocks,and coal seams.On this basis,we extracted six seismic-geological characterization attributes that showed dominant effects on the tectonic coal distribution from the 3D seismic data and interpretation.We constructed a tectonic coal distribution prediction model incorporating multiple attributes using the gray correlation method.We then used this model to predict the distribution of soft coal in the No.3 coal seam in the testing area,and checked for the validity and feasibility of the method through excavation and CBM development well inspection,providing a novel approach for accurately predicting tectonic coal distribution.