吐哈盆地小草湖凹陷东缘侏罗系煤系烃源岩埋藏史、热演化史模拟

Research on the Burial History and the Thermal Evolution History of the Jurassic Coal-Measure Source Rocks in the Eastern Margin of Xiaocaohu Sag

小草湖凹陷东缘侏罗系是吐哈盆地台北凹陷潜在油气勘探地层,但目前该地层烃源岩埋藏情况及生烃潜力未落实。本次研究利用盆地模拟技术结合实际数据对小草湖凹陷东缘侏罗系煤系烃源岩的埋藏史、热演化史进行了模拟分析。研究结果显示,侏罗系沉积速率最大可达70 m/Ma;从侏罗系开始研究区地层热流值一直处于减小状态,模拟所得各井最大温度在120~160℃;研究区中、下侏罗统烃源岩大约在白垩纪晚期—侏罗纪早期开始进入早期生油阶段,对应的门限深度大约为2200 m,现今处于低成熟中等成熟阶段。该结果对小草湖地区油气资源勘探开发具有一定的借鉴意义。

In this study,the burial history and thermal evolution history of coal-derived hydrocarbon source rocks in the eastern margin of Xiaocaohu sag were simulated and analyzed by using basin simulation technology and actual data.The results show that Jurassic is the main deposition period of the strata in the study area,and the maximum deposition rate of the strata can be 70 m/Ma.The heat flow value of the strata has been decreasing since the Jurassic,and the maximum temperature of each well obtained from the simulation is between 120℃and 160℃.The hydrocarbon source rocks of the Middle and Lower Jurassic in the study area entered the early oil production stage in almost the late Cretaceous-early Jurassic,corresponding to a threshold depth of about 2200 m,and are now in the low-middle maturity stage.The results have some implications for the exploration and development of oil and gas resources in the Xiaocaohu area.