页岩储层CO_(2)吸附解吸行为及弥散特征  

CO_(2)adsorption/desorption behaviors and dispersion characteristics in shale reservoirs

作　　者：魏兵[1] 陈海龙 刘帅 赵金洲[1] Kadet Valeriy WEI Bing;CHEN Hailong;LIU Shuai;ZHAO Jinzhou;Kadet VALERIY(State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation//Southwest Petroleum University,Chengdu,Sichuan 610500,China;No.12 Oil Production Plant,PetroChina Changqing Oilfield Company,Qingyang,Gansu 745000,China;Gubkin Russian State University of Oil and Gas,Moscow 119991,Russia)

机构地区：[1]油气藏地质及开发工程全国重点实验室·西南石油大学,四川省成都市610500 [2]中国石油长庆油田公司第十二采油厂 [3]古勃金国立石油与天然气大学

出　　处：《天然气工业》2024年第12期176-186,共11页Natural Gas Industry

基　　金：国家重点研发计划项目“页岩油藏CO_(2)驱油协同碳封存关键理论与方法研究”(编号:2023YFE0120700);高等学校学科创新引智计划项目“深层海相页岩气高效开发学科创新引智基地”(编号:D18016);四川省杰出青年科学基金“非常规油气藏提高采收率理论与方法”(编号:2023NSFSC1954)。

摘　　要：CO_(2)在页岩储层中的吸附/解吸行为是CO_(2)驱替页岩油气及CO_(2)地质封存的理论基础,研究驱替过程中的弥散特征对于评估二者混合程度、产出气纯度、采收率提高及CO_(2)封存效果具有重要意义。为此,以四川盆地下志留统龙马溪组和鄂尔多斯盆地上三叠统延长组页岩储层为研究对象,通过CO_(2)等温吸附和CO_(2)驱替CH4物理模拟实验,采用体积法和动态柱突破法,系统研究了不同页岩储层CO_(2)吸附量与温度、压力、页岩物性(有机碳含量、矿物组成、孔隙度和比表面积)的关系以及CO_(2)注入速度对弥散系数的影响规律。研究结果表明:①CO_(2)在页岩储层的吸附量随压力增加逐渐增大,当压力大于12 MPa后吸附量达到饱和状态,饱和吸附量为1.8~8.1 cm^(3)/g;②CO_(2)饱和吸附量与温度呈负相关关系,而与压力、页岩有机碳含量、比表面积和孔隙体积呈正相关关系;③CO_(2)驱替CH4的弥散过程处于对流与扩散共同主导的过渡区域,其表观弥散系数在10-7 m^(2)/s数量级且与CO_(2)注入速度呈线性相关关系。结论认为,研究成果揭示了CO_(2)弥散规律,初步证实了页岩储层注CO_(2)提高页岩油气采收率与碳封存的可行性,同时为开发方案优化设计提供了关键参数,为相关研究和工程实践奠定了理论基础。CO_(2)adsorption/desorption behaviors in shale reservoirs are the theoretical base of CO_(2)flooding and geological storage in shale.Studying the dispersion characteristics in the process of displacement is of great significance in evaluating the mixing degree of CO_(2)and oil/gas,the purity of produced gas,the enhanced oil recovery and the CO_(2)storage effect.Taking the shale reservoirs in the Lower Silurian Longmaxi Formation of the Sichuan Basin and the Upper Triassic Yanchang Formation of the Ordos Basin as examples,this paper analyzes the relationships of CO_(2)adsorption capacity of shale reservoirs with temperature,pressure,and shale physical properties(TOC,mineral composition,porosity,and specific surface area),and the influence of CO_(2)injection rate on dispersion coefficient by using the volume and dynamic column breakthrough methods,through physical simulation experiments of CO_(2)isothermal adsorption and CO_(2)displacing CH4.The following results are obtained.First,the CO_(2)adsorption capacity of shale reservoirs increases gradually with pressure.When the pressure exceeds 12 MPa,the adsorption capacity gets saturated,with a saturation adsorption capacity between 1.8 cm^(3)/g and 8.1 cm^(3)/g.Second,the CO_(2)saturation adsorption capacity is negatively correlated with temperature,and positively correlated with pressure,shale TOC,specific surface area,and pore volume.Third,the dispersion process of CO_(2)displacing CH4 occurs in the transitional zone dominated by convection and diffusion,whose apparent dispersion coefficient is in the order of 10-7 m^(2)/s and in a linear correlation with the CO_(2)injection rate.The research results reveal the dispersion patterns of CO_(2),and preliminarily confirm the feasibility of injecting CO_(2)to improve shale oil and gas recovery and carbon storage in shale reservoirs,while providing key parameters for the optimal development planning and laying a theoretical basis for related researches and engineering practices.

关 键 词：页岩气储层 注CO_(2)提高采收率 碳封存 吸附 解吸 CO_(2)驱替 饱和吸附量 页岩物性 弥散特征 

分 类 号：TE122.23[石油与天然气工程—油气勘探]