二氧化碳在致密储层基质中的作用距离研究  

Research on CO_(2) Matrix Penetration Distance in Tight Reservoirs

作　　者：牟建业[1] 闫骁伦 张士诚[1] 石磊 黎东 马新仿[1] MOU Jianye;YAN Xiaoun;ZHANG Shicheng;SHI Lei;LI Dong;MA Xinfang(College of Petroleum Engineering,China University of Petroleum(Beijing),Changping 102249,Beijing,China;Changqing Downhole Service Company,CNPC Chuanqing Drilling Engineering Co.,Ltd.,Xi'an 710016,Shaanxi,China;Xinjiang Xinyitong Petroleum Technology Co.,Ltd.,Karamay 834000,Xinjiang,China)

机构地区：[1]中国石油大学(北京)石油工程学院,北京昌平102249 [2]中国石油集团川庆钻探工程有限公司长庆井下技术作业公司,陕西西安710018 [3]新疆新易通石油科技有限公司,新疆克拉玛依834000

出　　处：《新疆石油天然气》2024年第3期64-71,共8页Xinjiang Oil & Gas

基　　金：克拉玛依市科学技术局科研课题“非常规油气藏CO_(2)压裂提高采收率技术研究与应用”(HX20231166);中国石油集团川庆钻探工程有限公司科研课题“CO_(2)与页岩储层及原油作用机理实验测试”(HX20230957)。

摘　　要：致密油衰竭开采过程中压力、产量下降较快,补充地层能量是提高原油采收率的必要措施。CO_(2)是常用补能介质之一(CO_(2)吞吐、前置蓄能),CO_(2)增产效果与其在储层中的作用距离息息相关,针对该问题从实验和数值模拟两方面开展了CO_(2)在致密储层基质中的作用距离研究。CO_(2)传质包括对流和扩散两种方式,首先采用高温高压反应釜和致密储层岩心进行CO_(2)扩散实验,结合Fick径向扩散模型,测得了CO_(2)在致密岩心中的扩散系数;然后采用CMG软件进行CO_(2)对流、扩散建模,基于模型进行广泛的数值模拟,分析渗透率、扩散系数、驱替时间对CO_(2)作用距离的影响。研究表明,扩散系数与渗透率有关,在目标储层岩心渗透率级别下,扩散系数在10^(-10)~10^(-8)m^(2)/s范围;CO_(2)作用距离取决于对流和扩散作用,扩散作用对CO_(2)作用距离影响明显,渗透率越低,扩散作用影响越明显,渗透率越高,对流作用越主导;渗透率是CO_(2)在基质中作用距离的决定性因素;CO_(2)在致密储层基质中的作用距离较小,60d的作用距离不到10m。During depletion recovery of tight oil,the reservoir pressure and production rate decline rapidly.Energy supplement is a necessary measure to enhance oil recovery.CO_(2) is a common medium used for energy replenishment(CO_(2) huff and puff,energy re-charging by CO_(2) prepad).The performance of CO_(2)-assisted enhanced oil recovery(EOR)is highly dependent on the penetration dis-tance.Therefore,the penetration distance of CO_(2) through the matrix of tight reservoirs was investigated via laboratory experiments and numerical simulation.Mass transfer of CO_(2) involves both convection and diffusion.Firstly,CO_(2) diffusion experiments were performed using a high-temperature high-pressure reactor and the cores of a tight formation.Based on the experimental results and Fick's diffu-sion model,the diffusion coefficient of CO_(2) was obtained.Next,CMG was used to build a model of CO_(2) convection and diffusion,and extensive numerical simulations were performed to analyze permeability,considering the effect of diffusion and flooding duration on CO_(2) penetration distance.The results show that the diffusion coefficient is dependent on permeability.The diffusion coefficient ranges from 10^(-10) to 10^(-8) m^(2)/s at the permeability level of the target formation.Diffusion and convention both affect the CO_(2) penetration dis-tance.Yet,the effects of convection are dominant with higher permeability,while those of diffusion are stronger with lower permeabili-ty.Permeability is a decisive factor of the matrix penetration of CO_(2).The CO_(2) penetration in tight reservoir matrix is rather low and reaches less than 10 m after 60 days.

关 键 词：致密储层 CO_(2)驱油 作用距离 扩散系数 提高采收率 数值模拟 

分 类 号：TE357.1[石油与天然气工程—油气田开发工程]