陇东长7致密油藏气驱喉道动用半径下限
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摘要
相比水驱,气驱能够波及到较小的喉道,研究气驱过程中气体所能波及到的最小喉道半径很有意义。选择常见的3种气驱用气:CO_2、N_2和空气,在驱替实验的不同阶段进行核磁共振测试,并选择相应岩心的平行样进行高压压汞测试。通过对比2种测试方法计算出来的喉道半径分布,计算出相应的转换系数C和n。再根据气驱过程中的T_2截止值,使用各自转换系数求得对应的喉道动用半径。实验结果表明,驱替压差越大,驱油效率越高,其中CO_2的变化幅度最高。同时发现,驱替压差越大,喉道动用半径越小,在驱替压差达到6 MPa下,气驱动用半径基本稳定。该方法为致密油储层研究气驱可行性提供了评价依据,在实际生产过程中需要综合评价选择最优的驱替用气及驱替压差。
Compared with the water flooding, the gas flooding can sweep to the smaller throats, so it is meaningful to study the minimum swept throat radius during the gas flooding. Three common gas flooding gases were selected: CO_2, N_2 and air, the NMR test was performed at different stages of the displacing experiment. At the same time, the high-pressure mercury injecting test was conducted for the parallel sample of the corresponding core. By comparing the throat radius distributions calculated by the two testing methods, the transferring coefficient C and n were calculated. And then, with the help of the T_2 cutoff value in the gas flooding process, the corresponding gas-flooding developed throat radii were finally obtained by themselves respective converting coefficients. The experimental results show that the larger the displacing differential is, the higher the oil displaced efficiency will be, and the change of the CO_2 is the biggest. At the same time, it is found that the larger the displacing pressure difference is, the smaller the developed throat radius will be, and the gas-flooded throat radius is basically stable when the displacing pressure difference reaches 6-8 MPa. This method provides an evaluating evidence for the study of the feasibility of the gas flooding in the tight oil reservoirs, in the actual production process, the comprehensive evaluation is needed for the selection of the optimal displacing gas and displacing pressure difference.
Compared with the water flooding, the gas flooding can sweep to the smaller throats, so it is meaningful to study the minimum swept throat radius during the gas flooding. Three common gas flooding gases were selected: CO_2, N_2 and air, the NMR test was performed at different stages of the displacing experiment. At the same time, the high-pressure mercury injecting test was conducted for the parallel sample of the corresponding core. By comparing the throat radius distributions calculated by the two testing methods, the transferring coefficient C and n were calculated. And then, with the help of the T_2 cutoff value in the gas flooding process, the corresponding gas-flooding developed throat radii were finally obtained by themselves respective converting coefficients. The experimental results show that the larger the displacing differential is, the higher the oil displaced efficiency will be, and the change of the CO_2 is the biggest. At the same time, it is found that the larger the displacing pressure difference is, the smaller the developed throat radius will be, and the gas-flooded throat radius is basically stable when the displacing pressure difference reaches 6-8 MPa. This method provides an evaluating evidence for the study of the feasibility of the gas flooding in the tight oil reservoirs, in the actual production process, the comprehensive evaluation is needed for the selection of the optimal displacing gas and displacing pressure difference.
引文
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[16]孙小龙,张宪国,林承焰,等.基于核磁共振标定的高压压汞孔喉分布定量评价方法[J].岩矿测试,2017,36(6):618-624.SUN Xiaolong,ZHANG Xianguo,LIN Chengyan,et al.Quantitative evaluation method of HPMI pore-throat distribution based on NMR calibration[J].Rock and Mineral Analysis,2017,36(6):601-607.
[17]肖佃师,卢双舫,陆正元,等.联合核磁共振和恒速压汞方法测定致密砂岩孔喉结构[J].石油勘探与开发,2016,43(6):961-970.XIAO Dianshi,LU Shuangfang,LU Zhengyuan,et al.Combining nuclear magnetic resonance and rate-controlled porosimetry to probe the pore-throat structure of tight sandstones[J].Petroleum Exploration and Development,2016,43(6):961-970.
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[21]祝海华,钟大康,姚泾利,等.碱性环境成岩作用及对储集层孔隙的影响:以鄂尔多斯盆地长7段致密砂岩为例[J].石油勘探与开发,2015,42(1):51-59.ZHU Haihua,ZHONG Dakang,YAO Jingli,et al.Alkaline diagenesis and its effects on reservoir porosity:A case study of Upper Triassic Chang 7 tight sandstones in Ordos Basin,NW China[J].Petroleum Exploration and Development,2015,42(1):51-59.
[22]LIU G F,BAI Y X,FAN Z Q,et al.Determination of Klinkenberg permeability conditioned to pore-throat structures in tight formations[J].Energies,2017,10 (10):1575-1591.
[23]LI A,DING W L,WANG R Y,et al.Petrophysical characterization of shale reservoir based on nuclear magnetic resonance (NMR) experiment:A case study of Lower Cambrian Qiongzhusi Formation in Eastern Yunnan Province,South China[J].Journal of Natural Gas Science and Engineering 2017,37:29-38.
[24]李爱芬,任晓霞,王桂娟,等.核磁共振研究致密砂岩孔隙结构的方法及应用[J].中国石油大学学报(自然科学版),2015,39(6):92-98.LI Aifen,REN Xiaoxia,WANG Guijuan,et al.Characterization of pore structure of low permeability reservoirs using a nuclear magnetic resonance method[J].Journal of China University of Petroleum(Edition of Natural Science),2015,39(6):92-98.
[25]刘天定,赵太平,李高仁,等.利用核磁共振评价致密砂岩储层孔径分布的改进方法[J].测井技术,2012,36(2):119-123.LIU Tianding,ZHAO Taiping,LI Gaoren,et al.An improved method to evaluate pore size distribution of tight sandstone reservoir using NMR[J].Well Logging Technology,2012,36(2):119-123.
[26]王学武,杨正明,李海波,等.核磁共振研究低渗透储层孔隙结构方法[J].西南石油大学学报,2010,32(2):69-72.WANG Xuewu,YANG Zhengming,LI Haibo,et al.Nuclear magnetic resonance study on pore structure of low permeability reservoirs[J].Journal of Southwest Petroleum University (Science & Technology Edition),2010,32(2):69-72.
[27]李艳,范宜仁,邓少贵,等.核磁共振岩心实验研究储层孔隙结构[J].勘探地球物理进展,2008,31(2):129-132.LI Yan,FAN Yiren,DENG Shaogui,et al.Nuclear magnetic resonance core experiment study on reservoir pore structure[J].Progress in Exploration Geophysics,2008,31(2):129-132.
[2]王香增,任来义,贺永红,等.鄂尔多斯盆地致密油的定义[J].油气地质与采收率,2016,23(1):1-7.WANG Xiangzeng,REN Laiyi,HE Yonghong,et al.Definition of tight oil in Ordos Basin[J].Petroleum Geology and Recovery Efficiency,2016,23(1):1-7.
[3]曹维政,罗琳,张丽平,等.特低渗透油藏注空气、N2室内实验研究[J].大庆石油地质与开发,2008,27(2):113-117.CAO Weizheng,LUO Ling,ZHANG Liping,et al.Laboratory experiment on air injection and nitrogen injection in extra-low permeability reservoir[J].Petroleum Geology & Oilfield Development in Daqing,2008,27(2):113-117.
[4]SHENG J J.Enhanced oil recovery in shale reservoirs by gas injection[J].Journal of Natural Gas and Engineering,2015,22:252-259.
[5]WANG L,TIAN Y,YU X Y,et al.Advances in improved/enhanced oil recovery technologies for tight and shale reservoirs[J].Fuel,2017,210:425-445.
[6]PU W F,WEI B,JIN F Y,et al.Experimental investigation of CO2 huff-and-puff process for enhancing oil recovery in tight reservoirs[J].Chemical Engineering Research and Design,2016,111:269-276.
[7]LUO P,LUO W G,LI S.Effectiveness of miscible and immiscible gas flooding in recovering tight oil from Bakken reservoirs in Saskatchewan,Canada[J].Fuel,2017,208:626-636.
[8]LIU,P C,ZHANG X K,WU Y B,et al.Enhanced oil recovery by air-foam flooding system in tight oil reservoirs:Study on the profile-controlling mechanisms[J].Journal of Petroleum Science and Engineering,2017,150:208-216.
[9]WAN T,WANG W M,JIANG J Q,et al.Pore-scale analysis of gas huff-n-puff enhanced oil recovery and waterflooding process[J].Fuel,2018,215:561-571.
[10]潘伟义,张诗洋,伦增珉,等.动用孔隙界限实验及致密油开发方式[J].大庆石油地质与开发,2016,35(6):155-158.PAN Weiyi,ZHANG Shiyang,LUN Zengmin,et al.Experiment of the recoverable pore limits and tight oil developing methods[J].Petroleum Geology & Oilfield Development in Daqing,2016,35(6):155-158.
[11]李扬,张凤生,李建玉,等.川中大安寨段致密灰岩储层核磁共振T2谱特征与解析[J].油气地质与采收率,2017,24(1):11-18.LI Yang,ZHANG Fengsheng,LI Jianyu,et al.Characterization and evaluation of NMR T2 spectrum of the tight limestone reservoir in the Daanzhai Formation,Central Sichuan Basin[J].Petroleum Geology and Recovery Efficiency,2017,24(1):11-18.
[12]GAO H,LIU Y,ZHANG Z,et al.Impact of secondary and tertiary floods on microscopic residual oil distribution in medium-to-high permeability cores with NMR technique[J].Energy & Fuel,2015,29(8):4721-729.
[13]刘堂宴,王绍民,傅容珊,等.核磁共振谱的岩石孔喉结构分析[J].石油地球物理勘探,2003,38(3):328-333.LIU Tangyan,WANG Shaomin,FU Rongshan,et al.Analysis of rock pore throat structure of nuclear magnetic resonance spectrum[J].Oil Geophysical Prospecting,2003,38(3):328-333.
[14]王胜.用核磁共振分析岩石孔隙结构特征[J].新疆石油地质,2009,30(6):768-770.WANG Sheng.Analysis of rock pore structure characteristics by nuclear magnetic resonance[J].Xinjiang Petroleum Geology,2009,30(6):768-770.
[15]王振华,陈刚,李书桓,等.核磁共振岩心实验分析在低孔渗储层评价中的应用[J].石油实验地质,2014,36(6):773-779.WANG Zhenhua,CHEN Gang,LI Shuhuan,et al.Application of NMR core experimental analysis in evaluation of low-porosity and low-permeability sandstone reservoirs[J].Petroleum Geology and Experiment,2014,36(6):773-779.
[16]孙小龙,张宪国,林承焰,等.基于核磁共振标定的高压压汞孔喉分布定量评价方法[J].岩矿测试,2017,36(6):618-624.SUN Xiaolong,ZHANG Xianguo,LIN Chengyan,et al.Quantitative evaluation method of HPMI pore-throat distribution based on NMR calibration[J].Rock and Mineral Analysis,2017,36(6):601-607.
[17]肖佃师,卢双舫,陆正元,等.联合核磁共振和恒速压汞方法测定致密砂岩孔喉结构[J].石油勘探与开发,2016,43(6):961-970.XIAO Dianshi,LU Shuangfang,LU Zhengyuan,et al.Combining nuclear magnetic resonance and rate-controlled porosimetry to probe the pore-throat structure of tight sandstones[J].Petroleum Exploration and Development,2016,43(6):961-970.
[18]宁宁,李怡超,刘洪林,等.不同渗透率岩芯孔径分布及可动流体研究[J].西南石油大学学报(自然科学版),2018,40(2):91-97.NING Ning,LI Yichao,LIU Honglin,et al.Study on influence of permeability and distribution of pore diameters in rock cores on measurement of mobile fluid saturation[J].Journal of Southwest Petroleum University (Science & Technology Edition),2018,40(2):91-97.
[19]LI X C,KANG Y L,HAGHIGHI M.Investigation of pore size distributions of coals with different structures by nuclear magnetic resonance (NMR) and mercury intrusion porosimetry (MPI)[J].Measurement,2018,116:122-128.
[20]ZHANG P F,LU S F,LI J Q,et al.Petrophysical characterization of oil-bearing shales by low-field nuclear magnetic resonance (NMR)[J].Marine and Petroleum Geology,2018,89:775-785.
[21]祝海华,钟大康,姚泾利,等.碱性环境成岩作用及对储集层孔隙的影响:以鄂尔多斯盆地长7段致密砂岩为例[J].石油勘探与开发,2015,42(1):51-59.ZHU Haihua,ZHONG Dakang,YAO Jingli,et al.Alkaline diagenesis and its effects on reservoir porosity:A case study of Upper Triassic Chang 7 tight sandstones in Ordos Basin,NW China[J].Petroleum Exploration and Development,2015,42(1):51-59.
[22]LIU G F,BAI Y X,FAN Z Q,et al.Determination of Klinkenberg permeability conditioned to pore-throat structures in tight formations[J].Energies,2017,10 (10):1575-1591.
[23]LI A,DING W L,WANG R Y,et al.Petrophysical characterization of shale reservoir based on nuclear magnetic resonance (NMR) experiment:A case study of Lower Cambrian Qiongzhusi Formation in Eastern Yunnan Province,South China[J].Journal of Natural Gas Science and Engineering 2017,37:29-38.
[24]李爱芬,任晓霞,王桂娟,等.核磁共振研究致密砂岩孔隙结构的方法及应用[J].中国石油大学学报(自然科学版),2015,39(6):92-98.LI Aifen,REN Xiaoxia,WANG Guijuan,et al.Characterization of pore structure of low permeability reservoirs using a nuclear magnetic resonance method[J].Journal of China University of Petroleum(Edition of Natural Science),2015,39(6):92-98.
[25]刘天定,赵太平,李高仁,等.利用核磁共振评价致密砂岩储层孔径分布的改进方法[J].测井技术,2012,36(2):119-123.LIU Tianding,ZHAO Taiping,LI Gaoren,et al.An improved method to evaluate pore size distribution of tight sandstone reservoir using NMR[J].Well Logging Technology,2012,36(2):119-123.
[26]王学武,杨正明,李海波,等.核磁共振研究低渗透储层孔隙结构方法[J].西南石油大学学报,2010,32(2):69-72.WANG Xuewu,YANG Zhengming,LI Haibo,et al.Nuclear magnetic resonance study on pore structure of low permeability reservoirs[J].Journal of Southwest Petroleum University (Science & Technology Edition),2010,32(2):69-72.
[27]李艳,范宜仁,邓少贵,等.核磁共振岩心实验研究储层孔隙结构[J].勘探地球物理进展,2008,31(2):129-132.LI Yan,FAN Yiren,DENG Shaogui,et al.Nuclear magnetic resonance core experiment study on reservoir pore structure[J].Progress in Exploration Geophysics,2008,31(2):129-132.