Optimization of operational strategies for rich gas enhanced oil recovery based on a pilot test in the Bakken tight oil reservoir  

作　　者：Xincheng Wan Lu Jin Nicholas A.Azzolina Jin Zhao Xue Yu Steven A.Smith James A.Sorensen 

机构地区：[1]Energy&Environmental Research Center,University of North Dakota,15 North 23rd Street,Stop 9018,Grand Forks,ND,58202-9018,USA

出　　处：《Petroleum Science》2023年第5期2921-2938,共18页石油科学（英文版）

基　　金：supported by the U.S.Department of Energy National Energy Technology Laboratory under Award No.DEFE0024233;the North Dakota Industrial Commission under the Award Nos.G-04-080(BPOP 2.0)and G-051-98(BPOP 3.0).

摘　　要：Horizontal well drilling and multistage hydraulic fracturing have been demonstrated as effective approaches for stimulating oil production in the Bakken tight oil reservoir.However,after multiple years of production,primary oil recovery in the Bakken is generally less than 10%of the estimated original oil in place.Gas huff‘n’puff(HnP)has been tested in the Bakken Formation as an enhanced oil recovery(EOR)method;however,most field pilot test results showed no significant incremental oil production.One of the factors affecting HnP EOR performance is premature gas breakthrough,which is one of the most critical issues observed in the field because of the presence of interwell fractures.Consequently,injected gas rapidly reaches adjacent production wells without contacting reservoir rock and increasing oil recovery.Proper conformance control is therefore needed to avoid early gas breakthrough and improve EOR performance.In this study,a rich gas EOR pilot in the Bakken was carefully analyzed to collect the essential reservoir and operational data.A simulation model with 16 wells was then developed to reproduce the production history and predict the EOR performance with and without conformance control.EOR operational strategies,including single-and multiple-well HnP,with different gas injection constraints were investigated.The simulation results of single-well HnP without conformance control showed that a rich gas injection rate of at least 10 MMscfd was needed to yield meaningful incremental oil production.The strategy of conformance control via water injection could significantly improve oil production in the HnP well,but injecting an excessive amount of water also leads to water breakthrough and loss of oil production in the offset wells.By analyzing the production performance of the wells individually,the arrangement of wells was optimized for multiple-well HnP EOR.The multiwell results showed that rich gas EOR could improve oil production up to 7.4%by employing conformance control strategies.Furthermore,replaci

关 键 词：Rich gas injection Bakken tight oil reservoir EOR strategies Conformance control Embedded discrete fracture model 

分 类 号：TE357[石油与天然气工程—油气田开发工程]