CO_2驱沥青质沉积量对致密砂岩油藏采收率的影响机理  

Study on influencing mechanism of asphaltene precipitation on oil recovery during CO_2 flooding in tight sandstone reservoirs

作　　者：王琛[1] 李天太[1] 高辉[1] 高媛 赵金省[1] 窦亮彬[1] WANG Chen;LI Tiantai;GAO Hui;GAO Yuan;ZHAO Jinsheng;DOU Liangbin(College of Petroleum Engineering,Xi’an Shiyou University,Xi’an City,Shaanxi Province,710065,China;Shaanxi Gas Group Co.,Ltd.,Xi’an City,Shaanxi Province,710016,China)

机构地区：[1]西安石油大学石油工程学院,陕西西安710065 [2]陕西燃气集团有限公司,陕西西安710016

出　　处：《油气地质与采收率》2018年第3期107-111,共5页Petroleum Geology and Recovery Efficiency

基　　金：国家自然科学基金项目"非常规致密砂岩油藏超临界CO2驱CO2-原油-微纳米级孔喉缝系统的相互作用机理研究"(51774236)和"酸性气体侵入井筒在钻井液内赋存状态及对瞬态流动影响研究"(51604224);中国石油科技创新基金项目"致密砂岩储层有效孔喉缝系统与致密油赋存评价新方法研究"(2017D-5007-0104)

摘　　要：为揭示CO_2驱过程中沥青质沉积量对致密砂岩油藏采收率的影响机理,选取3种不同沥青质含量的原油样品及相同渗透率的石英砂环氧树脂胶结人造岩心,模拟实际地层的温度、压力进行室内驱替实验,并通过核磁共振技术分析沥青质沉积对不同尺度孔喉中原油采收率的影响。实验结果表明:原油中沥青质含量越大,驱替过程中其沉积量越大;同时,岩心样品中的沥青质沉积量也随着CO_2注入量的增加而增加;驱替实验的最终采收率受沥青质沉积量的影响,沉积量越大,采收率越低。核磁共振技术测试结果表明,沥青质沉积对较大孔喉(2.0~200.0 ms)的采收率无明显影响。但是,对于较小孔喉(0.1~2.0 ms),沥青质沉积会产生一定程度的堵塞效应,导致剩余油难以采出,最终影响整体的采收率。In order to reveal the influencing mechanism of asphaltene precipitation on oil recovery during CO2flooding in the tight sandstone reservoirs,three kinds of crude oil samples with different asphaltene contents and low-permeability artificial cores(epoxy resin cemented quartz sand)were selected for flooding tests.The flooding tests were carried out by stimulating actual formation temperature and pressure.The effect of asphaltene precipitation on the oil recovery of different scales of pore throat was analyzed by nuclear magnetic resonance(NMR)technique.The results show that the amount of asphaltene precipitation is proportionate to asphaltene contents of the crude oil during flooding.It also increases with the increasing CO2injection volume.At the same time,the oil recovery will be affected by asphaltene,which decreases with the increasing precipitation amount.The results of NMR test show that the asphaltene precipitation had little effect on the oil recovery of the larger pore-throats(2.0-200.0ms).However,the asphaltene precipitation produced a certain degree of clogging in the smaller pore-throats(0.1-2.0ms),resulting in the remaining oil being difficult to be recovered and ultimately affecting the overall recovery.

关 键 词：致密砂岩CO2驱 沥青质沉积 采收率 核磁共振技术 影响机理 

分 类 号：TE357.42[石油与天然气工程—油气田开发工程]