盘关向斜火烧铺井田重烃含量异常的控制因素
Controlling factors of abnormal heavy hydrocarbon content in Huoshaopu mine field of Pansyncline
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摘要: 为了查明火烧铺井田煤中重烃异常分布特征及其控制因素,进而为区内煤层气勘探和盆地 深部重烃分布规律以及煤矿井下瓦斯抽采、矿井瓦斯防治提供参考。 首先,结合以往地面、井下不 同煤层钻孔瓦斯测试结果对深部进行地面瓦斯地质补充勘探、采样测试、气测录井、注入压降测试、 吸附解吸等多种技术综合分析各煤层中重烃含量特征;其次,分析重烃在平面、层域上的分布规律; 然后,分析重烃分布特征与地质构造、煤层埋深、水文地质条件、顶板封闭性、沉积环境和煤岩煤质 以及煤储层原岩应力场、渗透率的旋回性等多种因素的相关性;最后,总结火烧铺井田煤层中重烃 异常分布的形成机理及其富集模式。 结果表明井田内各煤层的气成分中含有一定量的重烃,重烃 的含量为 0.05 ~ 7.78 cm3 / g,平均为 2.35 cm3 / g;体积分数为 0.22% ~ 46.93%,平均为 18.42%;且存 在局部异常富集地段;各煤层气中重烃的含量与煤层埋深呈正相关性,各岩性段的平均含量由上向 下逐渐增高,不同编号煤层体积分数中 14 煤最高、22 煤最低;而重烃的含量中 14 煤最高、3 煤最 低,从上至下煤层中重烃的含量变化形态具有“ M” 型形态特征;重烃的异常分布主要受构造和生烃 母岩的控制,同时受水文地质、顶板岩性、顶板岩层完整性、沉积环境、煤岩煤质等地质因素的控制, 并构建了盘关向斜的重烃异常富集模式;研究成果可以为井田内深部煤层气勘探和矿井深部瓦斯 抽采和矿井瓦斯灾害防治提供参考,建议煤矿及地质勘查下一步应加强对矿井瓦斯成分、含量测试 中对重烃的测量以及其对瓦斯突出、爆炸以及发电利用的影响研究。Abstract: In order to provide a reference for the exploration of coal⁃bed gas, the distribution law of heavy hydrocarbon in the deep part of the Huoshaopu coalfield, the underground gas drainage, and the gas prevention and control in the coal mines, this study tries to find out the abnormal distribution characteristics and control factors of heavy hy⁃ drocarbon in the coals at the Huoshaopu coalfield.Firstly, combined with the previous gas test results of different coal seams, the paper comprehensively analyzed the characteristics of heavy hydrocarbon content in each coal seam by using the techniques of gas geological supplementary exploration, sampling test, gas logging, injection pressure drop test, adsorption and desorption, etc. Secondly, the distribution law of heavy hydrocarbon in the plane and layer domain was analyzed. Thirdly, the correlation between the distribution characteristics of heavy hydrocarbons and various factors such as geological structure, coal seam burial depth, hydrogeological conditions, roof sealing, depositional environment and coal rock quality, as well as coal reservoir in⁃situ rock stress field, permeability and other factors was analyzed. Finally, the formation mechanism and enrichment mode of abnormal distribution of heavy hydrocarbons in the coal seams of Huoshaopu minefield were summarized. The results show that there are a certain amount of heavy hydrocarbon in the gas composition of each coal seam in the mine⁃field, the content of heav⁃ y hydrocarbon is 0.05-7.78 m3 / t, the average is 2.35 m3 / t, the volume percentage is 0.22%-46.93%, the average is 18.42%, and there are local abnormal enrichment sections. The content of heavy hydrocarbon in each coal bed gas is positively correlated with the depth of coal bed. The average content of each lithologic section increases gradually from top to bottom. The heavy hydrocarbon content of Coal 14 is the highest and Coal 3 is the lowest, and the variation of heavy hydrocarbon content from the top to the bottom of the coal seam has the characteristic of “M” type. The ab⁃ normal distribution of heavy hydrocarbon is mainly controlled by structure and source rock, at the same time, it is controlled by such geological factors as hydrogeology, roof lithology, roof rock layer integrity, sedimentary environ⁃ ment, coal, rock and coal, etc. The research results can provide a reference for deep coalbed methane exploration, deep gas extraction and the prevention and control of mine gas disasters. It is suggested that the coal mine and geological exploration should strengthen the measurement of heavy hydrocarbons in the mine gas composition and content test, and the study on its impact on gas outburst,explosion and power generation.