沁水盆地煤系非常规天然气共生聚集机制

沁水盆地煤系非常规天然气(煤系"三气")资源丰富,研究煤系非常规天然气的共生聚集机制有助于天然气资源的综合利用。依托煤系有机地化与储层物性相关测试数据,分析了煤系非常规天然气的生烃物质基础与储层特征;基于典型钻孔的沉积序列、岩性组合和气测资料,建立了三类煤系非常规天然气共生模式并探讨了其在层序格架内的分布特征;通过成藏过程和成藏动力分析,评估了盆地内煤系非常规天然气的共采前景。研究认为:沁水盆地煤系非常规天然气生烃物质基础雄厚,天然气生成、运聚的宏观动力条件和储层条件时空配置得当,共生成藏条件良好;石炭-二叠系山西组与太原组发育"三气"共生和两种"二元"气藏共生组合,联合勘探开发前景较好,页岩气和致密砂岩气单独开发风险较大。

Co-accumulating mechanisms of unconventional gas in the coal measure of the Qinshui Basin

Qinshui basin has a good resource potential of unconventional gases in the coal measure.Study on the co-accumulation mechanisms of coal measure gas will be conducive to the comprehensive utilization of natural gas.Based on the test results of geo-chemistry and reservoir properties,the authors characterized the gas generation potential and gas reservoirs.Based on the depositional sequences,lithological associations and gas logging data of typical wells in this basin,the authors established three types of gas co-accumulations and discussed its distribution in the sequence framework.The co-mining prospect of natural gas in the coal measure was evaluated after investigating the forming process and dynamics of gas reservoirs.It was found that the coal measure in Qinshui basin has a solid basis for natural gas generation and the dynamics of gas generation,migration,accumulation and reservoir conditions were well coupled in the geological history,which provides good conditions for the co-accumulations of natural gas in different reservoirs.The Carboniferous-Permian Shanxi and Taiyuan formations developed three types of natural gas co-accumulation,with respect to the coalbed methane,shale gas and tight sandstone gas,indicating that the coal measure in this area is favorable for co-exploration and development.Development of the shale gas and tight sandstone gas separately,however,is at high risks.