在“双碳”战略背景下，开展煤中封存CO2和提高煤层气采收率(CO2-ECBM)研究有重要现实意义，我国也已开展多方位的先导性试验和工程示范。已有的工程实验表明，煤储层的排采程度对CO2注入的难易程度有重要影响，然而还缺少定量数据的支撑以及对CO2注入及驱煤层气的效果的评价。借助数值模拟手段，以沁水盆地柿庄北区块SX018-5H井煤层气地质和工程条件为基础，构建了含1口水平井和2口直井的3号煤层CO2-ECBM工区，设计了水平井排采0，1，2，3和4 a后，在1 a内连续注入万吨CO2，以及排采4 a后持续注入CO2共计6个注入驱替方案，对比了10 a模拟时间内注入CO2各方案及不注入CO2方案的气井产出和储层动态变化情况。研究结果表明，在沁水盆地南部柿庄北区块3号煤层地质条件下，水平井具有较高的CO2注气效率，3号煤层具有较大的封存潜力，注入万吨CO2主要封存在水平井筒(长700 m)附近60 m范围内；煤储层的排采程度，也就是注入CO2前储层的含气/含水饱和度，对CO2注入有重要影响，储层中甲烷排采越充分，越有利于CO2注入；CO2注入对邻近煤层气井的生产存在增加储层压力的“负”效应和驱替甲烷的“正”效应。要在CO2-ECBM项目中达到较好的驱替效果，一方面应增加煤储层的排采程度，另一方面应适当降低CO2注入井和煤层气生产井距。

Under the background of “double carbon” strategy,it is of great practical significance to carry out the re⁃search on carbon dioxide sequestration and enhanced coalbed methane recovery (CO2 -ECBM) in coal reservoir.In terms of the research mentioned above,China has carried out some multi⁃faceted pilot tests and engineering demon⁃strations. The existing engineering experiments show that the drainage degree of coal reservoir has an important impacton the difficulty of carbon dioxide injection,and then there is a lack of quantitative data support and evaluation of the effect of carbon dioxide injection to enhance coalbed methane recovery. By means of numerical simulation,basedon the coalbed methane geological and engineering conditions of SX018-5H well in the Shizhuangbei Block of theQinshui Basin,China,this paper establishes the CO2 -ECBM working area of No.3 coal seam with one horizontal welland two vertical wells. Six injection displacement schemes are designed for horizontal wells to continuously inject10 000 t of carbon dioxide within 1 year after 0,1,2,3 and 4 years,and to continuously inject carbon dioxide after4 years production. The gas well production and reservoir performance of each scheme without carbon dioxide injectionand carbon dioxide injection during the 10-year simulation time are compared. The results show that under the geolog⁃ical conditions of No. 3 coal seam in the Shizhuangbei block in the south of the Qinshui basin, the horizontalwell has higher CO2 gas injection efficiency,the No.3 coal seam has great storage potential,and the injection of10 000 t of CO2 is mainly stored in the range of 60 m near the horizontal wellbore (700 m in length). The drain⁃age degree of coal reservoir,that is,the gas / water saturation of the reservoir before CO2 injection,has an important im⁃pact on CO2 injection,the more fully methane is discharged from the reservoir,the more favorable it is for CO2 injec⁃tion. The CO2 injection has a “negative” effect of increasing reservoir pressure and a “positive” effect of methane dis⁃placement on the production of adjacent coalbed gas wells. In order to achieve a better displacement effect in the CO2 -ECBM project,on the one hand,the drainage degree of coal reservoir should be increased,on the other hand,the spac⁃ing between CO2 injection wells and coalbed methane production wells should be appropriately reduced.