枯竭页岩气储层CO_(2)地质封存机理及潜力评估方法  

Mechanism and potential evaluation method of CO_(2) geological storage in depleted shale gas reservoirs

作　　者：成其 汤积仁[1,2] 卢义玉[1,2] 陆朝晖[1,2] 贾云中[1,2] 周军平[1,2] 张弛[2,3] CHENG Qi;TANG Jiren;LU Yiyu;LU Zhaohui;JIA Yunzhong;ZHOU Junping;ZHANG Chi(State Key Laboratory of Coal Mine Disaster Dynamics and Control,Chongqing University,Chongqing 400030,China;School of Resources and Safety Engineering,Chongqing University,Chongqing 400030,China;Sinopec Chongqing Fuling Shale Gas Exploration and Development Co.,Ltd.,Chongqing 408000,China)

机构地区：[1]重庆大学煤矿灾害动力学与控制全国重点实验室,重庆400030 [2]重庆大学资源与安全学院,重庆400030 [3]中石化重庆涪陵页岩气勘探开发有限公司,重庆408000

出　　处：《煤炭学报》2025年第3期1695-1704,共10页Journal of China Coal Society

基　　金：国家自然科学基金面上资助项目(52274074);中央高校基本科研业务费优秀青年团队资助项目(2023CDJYXTD-001);重庆市杰出青年科学基金资助项目(cstc2021jcyj-jqX0007)。

摘　　要：页岩气在我国已实现大规模商业化开发,未来大量资源枯竭的页岩气水平井可提供巨大的CO_(2)封存容量。但页岩气储层的地质特征与深部咸水层、油气藏等常规封存地质体有显著区别,目前CO_(2)在页岩地层中的圈闭机理、封存机制及封存潜力评估方法有待进一步研究。以页岩气储层的地质特征为基础,分析了CO_(2)在页岩气储层中的圈闭机理及封存机制。CO_(2)地质封存可以视作页岩气生产的逆过程,主要的封存空间为产出页岩气所占据的原始孔裂隙空间。基于改造储层体积(SRV)作为CO_(2)封存空间的前提,结合有效容积法和“游离-吸附-溶解”多重封存机制,以盖层安全性为约束条件,建立了页岩气储层CO_(2)封存潜力评估模型;基于我国页岩气开发的现状,初步评估了我国未来枯竭页岩气储层CO_(2)封存潜力。结果表明:在垂直方向上,毛细管力封闭是页岩盖层对CO_(2)的主要封闭机理;在水平方向上,SRV被未经改造的致密页岩包围,可形成对CO_(2)侧向运移的有效屏障。基于以上机理研究,结合我国页岩气勘探开发的一般经验,计算得到页岩气水平井单井控制SRV内的最大CO_(2)封存潜力可达71.2万t,其中游离封存机制的占比为41.82%,吸附封存机制的占比为56.79%,溶解封存机制的占比为1.39%。初步评估我国现有页岩气井的CO_(2)封存潜力为15.02亿t,未来新增页岩气井的封存潜力为121.04亿t。Large-scale commercial development of shale gas has been achieved in China,and in the future,a significant number of depleted shale gas horizontal wells could provide substantial CO_(2) sequestration capacity.However,the geolo-gical characteristics of shale gas reservoirs significantly differ from those of conventional sequestration geological bodies,such as deep saline aquifers,conventional oil and gas reservoirs.The mechanisms of CO_(2) sealing,trapping,and the meth-ods for assessing sequestration potential in shale formations require further study.Based on the geological characteristics of shale gas reservoirs,this paper analyzes the mechanisms of CO_(2) sealing and trapping within these reservoirs.CO_(2) geo-sequestration can be regarded as the reverse process of shale gas production,with the main storage space being the pore and fracture space originally occupied by the shale gas produced.Based on the premise of stimulated reservoir volume(SRV)as the CO_(2) storage space,combined with the effective volume method and“free-adsorption-dissolution”multiple storage mechanism,and with cap rock safety as the constraint condition,a shale gas reservoir CO_(2) storage potential evalu-ation model was established.According the current state of shale gas development in China,the CO_(2) sequestration poten-tial of China’s future depleted shale gas reservoirs’was preliminarily evaluated.The results indicate that,vertically,capil-lary sealing is the primary mechanism of shale caprock.Horizontally,the SRV is surrounded by unfractured dense shale,forming an effective barrier to lateral CO_(2) migration.Based on these mechanisms and general experiences from shale gas exploration and development in China,the maximum CO_(2) sequestration potential within the SRV controlled by a single horizontal well is estimated to be 712000 tons.The proportion of free,adsorption,and dissolution storage mechanism is 41.82%,56.79%,and 1.39%,respectively.The CO_(2) sequestration potential of existing shale gas wells in China is prelim-ina

关 键 词：CO_(2)地质封存 页岩气储层 圈闭机理 封存机制 封存潜力 

分 类 号：X701[环境科学与工程—环境工程] TE37[石油与天然气工程—油气田开发工程]