中马村矿二_1煤的煤层气地质学特征研究

Coalbed Gas Geological Characteristics of Ⅱ_1 Coal Seam in Zhongmacun Mine

在成煤作用中后期,含煤岩系经历了多期构造运动,煤岩体发生不同程度的破坏变形,导致煤层的含气性、渗透性及物理力学性质产生差异,直接影响煤层气开发工艺的选择和瓦斯抽采技术的实施。通过分析矿井煤田勘探和实际生产资料,结合实验室测试和井下踏勘,探讨了中马村矿二_1煤的煤层气地质学特征。结果表明:储层具有赋存稳定,厚度较大,含气量高,渗透性差,煤体结构软硬互层,异常高压储层分布范围广的特征,现今煤层气的含气量及其分布特征,受控于地质演化时期的生烃演化及构造和封闭条件。煤层的埋藏史经历了5个阶段,新近纪至今的沉降使得理论含气量有所增加,有利于煤层气的富集。煤层气含气量受断层控制明显,压扭性断层及封闭性断层附近具有高的含量,并且这些区域也是煤与瓦斯突出频发地区;开放性断层附近含量较低;煤层的直接顶板岩性为泥岩和砂质泥(页)岩,为煤层气的保存提供了有利条件。

In the later stage of coal formation, coal-bearing rock measures experience multi-stage tectonic movement, and coal and rock body has varying degrees of damage deformation, which resuhs in differences in coal seam gas, permeability and physical and mechanical properties. That directly affects the selection of coalbed methane development process and the implementation of gas extraction technology. Based on the analysis of mine coal field exploration and actual production data, combined with laboratory tests and downhole survey, this paper discusses the geothermal characteristics of coalbed methane in Zhongmacun Coal Mine. Results show that reservoir has characteristics of occurrence stability, large thickness, high gas content, poor permeability, soft and hard interbed of coal structure and wide distribution of abnormal high pressure reservoirs. The gas content and its distribution characteristics of coalbed methane are controlled by hydrocarbon evolution and tectonic and closed conditions during geological evolution. Burial history of the coal seam has gone through five stages. The settlement of the Neogene has made the theoretical gas content increased, which is beneficial to the enrichment of coalbed methane. Gas content of coalbed methane is obviously controlled by faults, and there are high contents in the vicinity of compressive torsional faults and closed faults, and these areas are also coal and gas outburst areas; the open roof is low in the vicinity of open fault, and direct roof lithology of coal seam is mudstone and sandy mud, which provides favorable conditions for the storage of coalbed methane.