扩散作用对低渗透油藏CO_2驱相渗特征的影响
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摘要
目前,对于CO_2驱多相渗流理论的研究大多没有考虑CO_2的扩散作用,使得其在预测见气时间等方面存在问题。应用压力降落法测定了气体在原油中的扩散系数,采用非稳态相渗实验方法进行了油气相对渗透率测定实验,分别研究了N_2和CO_2气体相渗曲线的差异以及不同压力下扩散作用对CO_2驱相渗的影响。研究结果表明,低渗透油藏CO_2驱过程中的扩散作用对油气相渗存在较大影响,CO_2的扩散作用对油相相对渗透率影响较大,对气相相对渗透率影响甚微,CO_2扩散作用的影响有利于增强油相渗流,进而降低残余油饱和度,提高原油采收率。
At present,most of the studies on multiphase seepage theory of CO_2 flooding do not consider the diffusion of CO_2,which makes it difficult to accurately predict gas breakthrough time. The diffusion coefficients of N_2 and CO_2 in crude oil were measured by pressure drop method,and the relative permeability of oil and gas was measured by unsteady relative permeability experiments. The difference of relative permeability curves between N2 and CO_2 and the effect of diffusion on relative permeability of CO_2 flooding under different pressures were studied. The results show that the diffusion of CO_2 gas during CO_2 flooding of low permeability reservoirs has great influence on relative permeability of oil phase,but little effect on relative permeability of gas phase,which is conducive to enhancing oil phase percolation,thereby reducing residual oil saturation and improving oil recovery.
At present,most of the studies on multiphase seepage theory of CO_2 flooding do not consider the diffusion of CO_2,which makes it difficult to accurately predict gas breakthrough time. The diffusion coefficients of N_2 and CO_2 in crude oil were measured by pressure drop method,and the relative permeability of oil and gas was measured by unsteady relative permeability experiments. The difference of relative permeability curves between N2 and CO_2 and the effect of diffusion on relative permeability of CO_2 flooding under different pressures were studied. The results show that the diffusion of CO_2 gas during CO_2 flooding of low permeability reservoirs has great influence on relative permeability of oil phase,but little effect on relative permeability of gas phase,which is conducive to enhancing oil phase percolation,thereby reducing residual oil saturation and improving oil recovery.
引文
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[2] ESPIE T. A new dawn for CO2EOR[C]. International Petroleum Technology Conference,2005.
[3] BANK G,RIESTENBERG D. CO2-enhanced oil recovery potential of the Appalachian Basin[C]. SPE Eastern Regional Meeting,2007:1-11.
[4]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,B0 Qiwei,CHEN Yueming. Laboratory investigation of CO2flooding[J]. Petroleum Exploration and Development,2005,32(2):110-112.
[5] DRIA D E,POPE G A,SEPEHRNOORI K. Three-phase gas/oil/brine relative permeabilities measured under CO2flooding conditions[J]. Special Reservoir Engineering,1993,8(2):143-150.
[6] ELGAGHAH S,ZEKRI A. Laboratory investigation of influences of initial oil saturation and oil viscosity on oil recovery by CO2miscible flooding[C]. SPE Europec/EAGE Annual Conference and Exhibition,2007:1-9.
[7] AMAO A M,SIDDIQUI S,MENUAR H,et al. A new look at the minimum miscibility pressure(MMP)determination from slimtube measurements[C]. SPE Improved Oil Recovery Symposium,2012:1-13.
[8] SHOJAE H,RASTEGAR R,JESSEN K. Experimental and modeling study of multicontact miscible displacements introduction[C]. SPE Improved Oil Recovery Symposium,2012:1-19.
[9]王少朋,侯吉瑞,赵凤兰,等.二氧化碳在油藏流体中的扩散系数研究进层[J].油田化学,2013,30(1):150-154.WANG Shaopeng,HOU Jirui,ZHAO Fenglan,et al. Research progress of diffusion coefficient of Carbon Dioxide in reservion fluids[J]. Oilfield Chemisitry,2013,30(1):150-154.
[10] MUNGAN N. An evaluation of carbon dioxide flooding[C]. Presentation at the SPE Western Regional,Long Beach California,March 20-22,1991.
[11]GRIGG R B,SCHECHTER D S. State of the industry in CO2flooding[C]. Presentation at the SPE Annual Technical Conference and Exhibition held in San Antonia,TX. 5-8 October,1997.
[12]FARAJZADEH R,ZITHA P L J,BRUINING J. Enhanced mass transfer of CO2into water:experiment and modeling[J]. Industrial&Engineering Chemistry Research,2009,48:6423-6431.
[13]李东东,侯吉瑞,赵凤兰,等.二氧化碳在原油中的分子扩散系数和溶解度研究[J].油田化学,2009,26(4):405-408.LI Dongdong,HOU Jirui,ZHAO Fenglan,et al. Study of molecular diffusion coefficients and solubility of Carbon Dioxide in a Jinlin Crude Oil[J]. Oilfield Chemistry,2009,26(4):405-408.