CO_2驱沥青质沉积量对致密砂岩油藏采收率的影响机理
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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 CO_2 flooding 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 CO_2 injection 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(2.0-200.0 ms). However,the asphaltene precipitation produced a certain degree of clogging in the smaller pore-throats(0.1-2.0 ms),resulting in the remaining oil being difficult to be recovered and ultimately affecting the overall recovery.
In order to reveal the influencing mechanism of asphaltene precipitation on oil recovery during CO_2 flooding 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 CO_2 injection 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(2.0-200.0 ms). However,the asphaltene precipitation produced a certain degree of clogging in the smaller pore-throats(0.1-2.0 ms),resulting in the remaining oil being difficult to be recovered and ultimately affecting the overall recovery.
引文
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[2]高云丛,赵密福,王建波,等.特低渗油藏CO2非混相驱生产特征与气窜规律[J].石油勘探与开发,2014,41(1):79-85.GAO Yuncong,ZHAO Mifu,WANG Jianbo,et al.Performance and gas breakthrough during CO2immiscible flooding in ultralow permeability reservoirs[J].Petroleum Exploration and Development,2014,41(1):79-85.
[3]郝永卯,薄启炜,陈月明.CO2驱油实验研究[J].石油勘探与开发,2005,32(2):110-112.HAO Yongmao,BO Qiwei,CHEN Yueming.Laboratory investigation of CO2flooding[J].Petroleum Exploration and Development,2005,32(2):110-112.
[4]李向良.温度和注入压力对二氧化碳驱油效果的影响规律实验[J].油气地质与采收率,2015,22(1):84-87,92.LI Xiangliang.Experimental study on the effect of temperature and injection pressure on CO2flooding[J].Petroleum Geology and Recovery Efficiency,2015,22(1):84-87,92.
[5]陈国利.二氧化碳驱开发效果评价方法[J].大庆石油地质与开发,2016,35(1):92-96.CHEN Guoli.Evaluating method of CO2flooding development effects[J].Petroleum Geology&Oilfield Development in Daqing,2016,35(1):92-96.
[6]郎东江,伦增珉,吕成远,等.致密砂岩储层CO2驱油特征的核磁共振实验研究[J].CT理论与应用研究,2016,25(2):141-147.LANG Dongjiang,LUN Zengmin,LüChengyuan,et al.Study ofdisplacement characteristics of CO2in tight sandstone reservoir by nuclear magnetic resonance[J].CT Theory and Applications,2016,25(2):141-147.
[7]张本艳,党文斌,王少朋,等.鄂尔多斯盆地红河油田长8储层致密砂岩油藏注CO2提高采收率[J].石油与天然气地质,2016,37(2):272-275.ZHANG Benyan,DANG Wenbin,WANG Shaopeng,et al.CO2-EOR in Chang8 tight sandstone reservoir of Honghe oilfield in Ordos Basin[J].Oil&Gas Geology,2016,37(2):272-275.
[8]胡伟,吕成远,王锐,等.水驱油藏注CO2非混相驱油机理及剩余油分布特征[J].油气地质与采收率,2017,24(5):99-105.HU Wei,LüChengyuan,WANG Rui,et al.Mechanism of CO2immiscible flooding and distribution of remaining oil in water drive oil reservoir[J].Petroleum Geology and Recovery Efficiency,2017,24(5):99-105.
[9]王建波,高云丛,宗畅,等.特低渗油藏CO2非混相驱水气交替注入见效特征[J].大庆石油地质与开发,2016,35(2):116-120.WANG Jianbo,GAO Yuncong,ZONG Chang,et al.Response characteristics of CO2-immiscible flooding WAG in the ultralow-permeability oil reservoirs[J].Petroleum Geology&Oilfield Development in Daqing,2016,35(2):116-120.
[10]贾英,孙雷,孙良田,等.向油藏中注CO2时引起的沥青质沉淀研究[J].新疆石油地质,2006,27(5):581-585.JIA Ying,SUN Lei,SUN Liangtian,et al.A study of asphaltene deposition caused by CO2injection in reservoirs[J].Xinjiang Petroleum Geology,2006,27(5):581-585.
[11]赵明国,赵宇.CO2驱油中沥青质沉积条件及对驱油效果影响的研究[J].科学技术与工程,2011,11(4):729-731,748.ZHAO Mingguo,ZHAO Yu.The study on depositional condition of bitumen and displacement characteristics effect of CO2flooding[J].Science Technology and Engineering,2011,11(4):729-731,748.
[12]PAPADIMITRIOU N I,ROMANOS G E,CHARALAMBOPOULOU G Ch,et al.Experimental investigation of asphaltene deposition mechanism during oil flow in core samples[J].SPEJ,2007,57(3/4):281-293.
[13]孙忠新.CO2驱替下沥青质沉积实验研究[J].油田化学,2010,27(4):374-376.SUN Zhongxin.Study on asphaltene deposition in the process of CO2flooding[J].Oilfield Chemistry,2010,27(4):374-376.
[14]张钧溢,赵凤兰,侯吉瑞,等.CO2驱替过程中沥青质沉积及其对原油采收率的影响[J].特种油气藏,2012,19(2):107-109.ZHANG Junyi,ZHAO Fenglan,HOU Jirui,et al.Asphaltene deposition and its impact on oil recovery during CO2flooding[J].Special Oil&Gas Reservoirs,2012,19(2):107-109.
[15]孙忠新.CO2驱油效果影响因素研究[D].大庆:大庆石油学院,2009.SUN Zhongxin.Study on influencing factors of CO2flooding[D].Daqing:Daqing Petroleum Institute,2009.
[16]李海波,朱巨义,郭和坤.核磁共振T2谱换算孔隙半径分布方法研究[J].波谱学杂志,2008,25(2):273-280.LI Haibo,ZHU Juyi,GUO Hekun.Methods for calculating pore radius distribution in rock from NMR T2spectra[J].Chinese Journal of Magnetic Resonance,2008,25(2):273-280.
[17]王崇阳.致密油藏注CO2实验研究[D].成都:西南石油大学,2016.WANG Chongyang.Experimental study on CO2flooding in tight oil reservoirs[D].Chengdu:Southwest Petroleum University,2016.