低渗透非均质多层储层CO_(2)驱油效果评价及储层伤害特征  

Evaluation of CO_(2) flooding effect and damage characteristics in low permeability heterogeneous multi-layer reservoirs

作　　者：张蕊[1] 李新强 李馨语 牛萌[3] 李荣[1] ZHANG Rui;LI Xinqiang;LI Xinyu;NIU Meng;LI Rong(School of Petroleum Engineering and Environmental Engineering,Yan’an University,Yan’an City,Shaanxi Province,716000,China;Engineering Technology Management Department of PetroChina Changqing Oilfield Company,Xi’an City,Shaanxi Province,710000,China;Exploration and Development Research Institute,Yanchang Oilfield Co.,Ltd.,Yan’an City,Shaanxi Province,716000,China)

机构地区：[1]延安大学石油工程与环境工程学院,陕西延安716000 [2]中国石油长庆油田分公司工程技术管理部,陕西西安710000 [3]延长油田股份有限公司勘探开发技术研究中心,陕西延安716000

出　　处：《油气地质与采收率》2022年第3期121-127,共7页Petroleum Geology and Recovery Efficiency

基　　金：陕西省教育厅专项科研计划项目“鄂尔多斯盆地吴起地区长8裂缝性碳酸盐岩储层保护技术研究”(20JK0992);延安大学校级科研计划项目“煤矸石制备絮凝剂处理油田污水试验研究”(YDQ2020-13);延安大学大学生创新创业训练计划项目“南堡油田保护油气层钻井液体系研究”(D2020118)。

摘　　要：CO_(2)在低渗透非均质多层储层中的驱油特征与在单层储层中存在差异。为明确非均质多层储层CO_(2)驱油特征,通过三管并联平行长岩心驱替实验,模拟低渗透非均质多层储层注CO_(2)驱替过程,评价非混相和混相压力下连续CO_(2)驱和水气交替驱后高、中、低渗透层的驱油效率,明确沥青质沉淀对非均质多层储层的伤害特征。结果表明,在非混相或混相压力下连续注入CO_(2),均会在高渗透层中快速突破,且混相压力下CO_(2)突破时间早于非混相压力下。突破后高渗透层对总采收率的贡献率大于91.7%,非混相和混相的中渗透层贡献率分别为5.6%和2.1%,低渗透层为0。CO_(2)突破转水气交替驱后,CO_(2)波及体积明显增大,中、低渗透层采收率大幅提高,然而中、低渗透层仍然是后期挖潜的主要方向。混相压力下沥青质沉淀对非均质多层储层的伤害主要在高渗透层后部,靠近出口端附近;而非混相压力下沥青质沉淀对储层的伤害主要在高渗透层前中部,靠近注入端附近,但伤害程度低于混相压力下。The oil displacement characteristics of CO_(2)in low permeability heterogeneous multi-layer reservoirs are differ⁃ent from those in single-layer reservoirs.To clarify the CO_(2)flooding characteristics in heterogeneous multi-layer reser⁃voirs,we simulated the CO_(2)flooding process in low permeability heterogeneous multi-layer reservoirs through the displace⁃ment experiments with three pipes of long core in parallel connection.The oil displacement efficiency of high,medium and low permeability layers after continuous CO_(2)flooding and water-alternating-gas(WAG)flooding were evaluated under im⁃miscible and miscible pressures.The damage characteristics of asphaltene precipitation to heterogeneous multi-layer reser⁃voirs were clarified.The results reveal that continuous injection of CO_(2)under immiscible or miscible pressures will lead to the rapid breakthrough of the high permeability layer,and the breakthrough of CO_(2)under miscible pressure is earlier than that under immiscible pressure.After the breakthrough,the contribution rate of the high permeability layer to the total re⁃covery factor is more than 91.7%,while those of the medium permeability layer under immiscible and miscible pressure are 5.6%and 2.1%,and that of the low permeability layer is 0.After CO_(2)flooding is converted to WAG flooding,the swept vol⁃ume of CO_(2)increases significantly,and the recovery factors of medium and low permeability layers are improved consider⁃ably.However,the medium and low permeability layers still represent the main direction for tapping the reservoir potential in the later stage.Under miscible pressure,the damage of asphaltene precipitation to heterogeneous multi-layer reservoirs mainly concentrates in the rear of the high permeability layer,near the outlet;while under immiscible pressure,it is mainly in the front and middle of the high permeability layer,near the inlet,but the degree of damage is lower than that under mis⁃cible pressure.The influence of asphaltene precipitation on the medium and l

关 键 词：CO_(2)驱 水气交替 非均质 沥青质沉淀 低渗透储层 

分 类 号：TE348[石油与天然气工程—油气田开发工程]