杂质气体对二氧化碳在废弃气藏咸水层埋存的影响  

Effect of impurities on CO_(2) sequestration in saline aquifers in abandoned gas reservoirs

作　　者：吕晓聪[1,2] 刘慧卿[1,2] 王敬[1,2] 东晓虎 拜杰[3] 沈旭东 LU Xiaocong;LIU Huiqing;WANG Jing;DONG Xiaohu;BAI Jie;SHEN Xudong(State Key Laboratory of Petroleum Resources and Prospecting,China University of Petroleum(Beijing),Beijing City,102249,China;MOE Key Laboratory of Petroleum Engineering,China University of Petroleum(Beijing),Beijing City,102249,China;Research Institute of Oil/Gas Technology,Changqing Oilfield Branch Company,PetroChina,Xi’an City,Shaanxi Province,710021,China)

机构地区：[1]中国石油大学(北京)油气资源与探测国家重点实验室,北京102249 [2]中国石油大学(北京)教育部重点实验室,北京102249 [3]中国石油长庆油田分公司油气工艺研究院,陕西西安710021

出　　处：《油气地质与采收率》2023年第2期153-161,共9页Petroleum Geology and Recovery Efficiency

基　　金：中国石油大学(北京)科研基金“泡沫强化咸水层CO_(2)封存机理研究”(2462022BJRC003)和“CCUS/CCS埋存地质体选区评价及监测关键技术研究”(2021ZZ01-05);国家自然科学基金企业创新发展联合基金项目“难采稠油多元热复合高效开发机理与关键技术基础研究”(U20B6003)。

摘　　要：废弃气藏是埋存二氧化碳的理想场所,但气藏中的杂质气体会影响二氧化碳在水中的溶解过程。针对此问题,建立了考虑逸度-活度的热力学模型,准确捕捉杂质气体-二氧化碳-咸水混合体系的热力学特征。在此基础上,采用基于算子的线性化数值方法,高效准确求解质量守恒方程,研究不同混合物对二氧化碳在咸水中扩散-对流的影响。以荷兰西佩尔尼斯气藏为例,分析并评价了废弃气藏二氧化碳埋存的可行性及潜力。研究结果表明,二氧化碳在咸水中的溶解度随压力的升高而增加,随温度及矿化度的升高而降低,相同压力下,25℃下的溶解度约为90℃下的2倍。不同杂质气体对二氧化碳溶解能力的影响不同,甲烷对二氧化碳溶解度降低程度最大,降低幅度约为12%。二维模拟结果表明,杂质气体会降低二氧化碳羽流指进的速度,延长对流触发的时间,5%的甲烷-二氧化碳混合体系对流触发时间是纯二氧化碳的2.5倍,但杂质气体对总的溶解量影响不大。西佩尔尼斯气藏模拟结果表明,废弃气藏开展二氧化碳埋存潜力巨大;短时间内,二氧化碳主要以游离气及束缚气形式存在,溶解气量较少。关井30 a后,游离气占74.2%,残余气占19.1%,溶解气仅占6.7%。Abandoned gas reservoirs are ideal sites for carrying out carbon dioxide(CO_(2))storage projects.However,impurities in gas reservoirs can affect the CO_(2) dissolution in saline aquifers.To this end,a fugacity-activity thermodynamic model is constructed to capture the features of impurities,CO_(2),and saline aquifers.On this basis,the operator-based linearization approach is implemented to solve the mass conservation equations accurately and efficiently.Then the effects of gas mixtures on CO_(2) diffusion-convection are studied.With the Pernis gas reservoir in the Netherlands as an example,the storage potential of abandoned gas reservoirs is evaluated.The results show that the CO_(2) solubility in saline aquifers increases with the rising pressure while decreases with higher temperature and salinity.At the same pressure,the CO_(2) solubility at 25℃is about twice that at 90℃.In addition,different impurities have different effects on CO_(2) dissolution,and CH4 reduces the CO_(2) solubility by around 12%.2D simulation results show that the fingering rate of CO_(2) plume in saline aquifers is limited by the impurities.Meanwhile,the onset time of convection is extended due to the impurities.The onset time of CO_(2) mixture with 5%methane is around 2.5 times that of pure CO_(2).Considering the long timescale,the final dissolution is not affected by the impurities significantly.Through the studies of the Pernis gas reservoir,abandoned gas reservoirs have a large potential for CO_(2) storage.In the short run,CO_(2) exists in porous media as free gas and residual gas,while the amount of dissolved gas is relatively small.In 30 years after shutting the wells,the free gas accounts for 74.2%,and residual gas is 19.1%,while only 6.7% gas is dissolved into the aquifer.

关 键 词：杂质气体 废弃气藏 二氧化碳溶解度 咸水层 基于算子的线性化方法 

分 类 号：TE122.3[石油与天然气工程—油气勘探]