地层水对凝析气藏注CO_2相态的影响
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摘要
常规的凝析气藏衰竭开发和注CO_2开发研究中均忽略了地层水的影响,这与真实情况存在偏差,有可能导致研究结果的不确定性加大。为此,基于CO_2—烃—水相平衡热力学模型,以一个实际近临界凝析气藏为例,通过相态模拟研究了地层水存在对凝析气藏反凝析相态特征和注CO_2相态的影响规律;计算了考虑地层水存在的凝析气定容衰竭反凝析液饱和度和剩余流体组成,以及注CO_2过程中凝析油气相体积分数和CO_2在凝析油气相中体积分数的变化规律。结果表明:1考虑地层水时定容衰竭的反凝析油饱和度更大,剩余流体重组分含量更高;2近临界凝析气藏压力衰竭过程中,由凝析气转变为挥发油的相变发生得更早;3在注CO_2过程中,地层水的存在使得CO_2对凝析油的反蒸发作用降低;4考虑地层水存在时凝析油相体积分数高约14%,CO_2在凝析油中溶解量比不考虑地层水大6%,CO_2含量高和压力较高时差异更明显,同时,地层水的存在也增强了CO_2的溶解封存能力。该研究成果对凝析气藏注CO_2提高采收率和温室气体CO_2埋存评价具有指导意义。
The impacts of formation water are generally ignored when gas condensate reservoirs are developed by means of conventional depletion and CO_2 injection, but this is not exactly the actual situations, possibly making the research results more uncertain. In this paper, a real near-critical gas condensate reservoir was taken as an example for study. Based on the CO_2–hydrocarbon–water phase equilibrium thermodynamic model, the impacts of formation water on retrograde condensation phase characteristics and phase behavior of CO_2 injected into gas condensate reservoirs were analyzed by means of phase simulation. The compositions of the remaining fluid and the retrograde condensate saturation of the constant volume depletion were calculated by taking such impacts into consideration. Besides, volume fraction of condensate oil/gas phase during CO_2 injection and the volume fraction changes of CO_2 in the condensate oil/gas phase were studied. It is indicated that the content of heavy constituents in remaining fluid and the retrograde condensate saturation of constant volume depletion are higher when the impacts of formation water are taken into account. During the pressure depletion of near-critical gas condensate reservoirs, the phase transition from gas condensate to volatile oil occurs earlier. In the process of CO_2 injection, the retrograde evaporation of CO_2 on condensate oil is weakened due to the presence of formation water. If the impacts of formation are considered, the volume fraction of condensate oil is 14% higher and the amount of CO_2 dissolved in the condensate oil increases by 6%. The difference is larger with the increase of pressure and CO_2 content. It is revealed that the dissolution and sequestration capacity of CO_2 is enhanced due to the presence of formation water. These research results play a guiding role in evaluating the CO_2 injection for enhancing the recovery of gas condensate reservoirs and CO_2(greenhouse gas) sequestration.
The impacts of formation water are generally ignored when gas condensate reservoirs are developed by means of conventional depletion and CO_2 injection, but this is not exactly the actual situations, possibly making the research results more uncertain. In this paper, a real near-critical gas condensate reservoir was taken as an example for study. Based on the CO_2–hydrocarbon–water phase equilibrium thermodynamic model, the impacts of formation water on retrograde condensation phase characteristics and phase behavior of CO_2 injected into gas condensate reservoirs were analyzed by means of phase simulation. The compositions of the remaining fluid and the retrograde condensate saturation of the constant volume depletion were calculated by taking such impacts into consideration. Besides, volume fraction of condensate oil/gas phase during CO_2 injection and the volume fraction changes of CO_2 in the condensate oil/gas phase were studied. It is indicated that the content of heavy constituents in remaining fluid and the retrograde condensate saturation of constant volume depletion are higher when the impacts of formation water are taken into account. During the pressure depletion of near-critical gas condensate reservoirs, the phase transition from gas condensate to volatile oil occurs earlier. In the process of CO_2 injection, the retrograde evaporation of CO_2 on condensate oil is weakened due to the presence of formation water. If the impacts of formation are considered, the volume fraction of condensate oil is 14% higher and the amount of CO_2 dissolved in the condensate oil increases by 6%. The difference is larger with the increase of pressure and CO_2 content. It is revealed that the dissolution and sequestration capacity of CO_2 is enhanced due to the presence of formation water. These research results play a guiding role in evaluating the CO_2 injection for enhancing the recovery of gas condensate reservoirs and CO_2(greenhouse gas) sequestration.
引文
[1]沈平平,廖新维.二氧化碳地质埋存与提高石油采收率技术[M].北京:石油工业出版社,2009.Shen Pingping,Liao Xinwei.The technology of carbon dioxide stored in geological media and enhanced oil recovery[M].Beijing:Petroleum Industry Press,2009.
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[4]朱忠谦.牙哈凝析气藏二次注气抑制反凝析机理及相态特征[J].天然气工业,2015,35(5):60-65.Zhu Zhongqian.Mechanism and phase behavior of retrograde condensation inhibition by secondary gas injection in the Yaha condensate gas reservoir[J].Natural Gas Industry,2015,35(5):60-65.
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[7]肖朴夫,杨正明,王学武,戴兴星.室内注二氧化碳微观驱油机理研究[J].西南石油大学学报:自然科学版,2015,37(4):161-165.Xiao Pufu,Yang Zhengming,Wang Xuewu,Dai Xingxing.A laboratory study on the micro mechanism of oil displacement with CO2fl ooding[J].Journal of Southwest Petroleum University:Science&Technology Edition,2015,37(4):161-165.
[8]郭平,景莎莎,彭彩珍.气藏提高采收率技术及其对策[J].天然气工业,2014,34(2):48-55.Guo Ping,Jing Shasha,Peng Caizhen.Technology and countermeasures for gas recovery enhancement[J].Natural Gas Industry,2014,34(2):48-55.
[9]Narinesingh J,Alexander D.CO2 enhanced gas recovery and geologic sequestration in condensate reservoir:A simulation study of the effects of injection pressure on condensate recovery from reservoir and CO2 storage effi ciency[C]//12th International Conference on Greenhouse Gas Control Technologies(GHGT-12),5-9 October2014,Austin,Texas,USA.DOI:http://dx.doi.org/10.1016/j.egypro.2014.11.334.
[10]Shtepani E.CO2 sequestration in depleted gas/condensate reservoirs[C]//SPE Annual Technical Conference and Exhibition,24-27 September 2006,San Antonio,Texas,USA.DOI:http://dx.doi.org/10.2118/102284-MS.
[11]Yuan Chengwu,Zhang Zhong,Liu Kaijian.Assessment of the recovery and front contrast of CO2 EOR and sequestration in a new gas condensate reservoir by compositional simulation and seismic modeling[J].Fuel,2015,142(1):81-86.
[12]侯大力,高黎惠,刘浩成,张梅珠,崔飞飞.近临界态凝析气藏地层流体特殊相态行为[J].天然气工业,2013,33(11):68-73.Hou Dali,Gao Lihui,Liu Haocheng,Zhang Meizhu,Cui Feifei.Dynamic phase behavior of near-critical condensate gas reservoir fl uids[J].Natural Gas Industry,2013,33(11):68-73.
[13]王长权,汤勇,杜志敏,陈亮,孙杨,潘毅,等.含水凝析气相态特征及非平衡压降过程产液特征[J].石油学报,2013,34(4):740-746.Wang Changquan,Tang Yong,Du Zhimin,Chen Liang,Sun Yang,Pan Yi,et al.Phase behaviors of condensate gas with vaporous water and liquid production characteristics in a non-equilibrium pressure drop process[J].Acta Petrolei Sinica,2013,34(4):740-746.
[14]石德佩,孙雷,刘建仪,常志强,李相方.高温高压含水凝析气相态特征研究[J].天然气工业,2006,26(3):95-97.Shi Depei,Sun Lei,Liu Jianyi,Chang Zhiqiang,Li Xiangfang.Phase behavior of wet condensate gas at high temperature and pressure[J].Natural Gas Industry,2006,26(3):95-97.
[15]刘志斌,刘道杰,田中敬.高温高压凝析气藏物质平衡方程的建立——考虑气藏气相水蒸气含量及岩石颗粒的弹性膨胀作用[J].天然气工业,2011,31(7):37-39.Liu Zhibin,Liu Daojie,Tian Zhongjing.Establishment of material balance equation of HPHT gas condensate reservoirs:Taking into account the water vapor content of gas phase and the elastic expansion of rock particles[J].Natural Gas Industry,2011,31(7):37-39.
[16]汤勇,杜志敏,孙雷,刘伟,陈祖华.CO2在地层水中溶解对驱油过程的影响[J].石油学报,2011,3(2):311-314.Tang Yong,Du Zhimin,Sun Lei,Liu Wei,Chen Zuhua.Infl uence of CO2 dissolving in formation water on CO2 fl ooding process[J].Acta Petrolei Sinica,2011,32(2):311-314.
[17]Turta AT,Sim SSK,Singhal AK,Hawkins BF.Basic investigations on enhanced gas recovery by gas-gas displacement[J].Journal of Canadian Petroleum Technology,2008,47(10):39-44.
[18]Juanes R,Spiteri EJ,Orr Jr FM,Blunt MJ.Impact of relative permeability hysteresis on geological CO2 storage[J].Water Resources Research,2006,42(12):395-397.
[19]Kokal S,Al-Dokhi M,Sayegh S.Phase behavior of a gas-condensate/water system[J].SPE Reservoir Evaluation&Engineering,2003,6(6):412-420.
[20]郭天民.多元汽-液平衡和精馏[M].北京:石油工业出版社,2002.Guo Tianmin.Multicomponent vapor-liquid phase equilibrium and distillation[M].Beijing:Petroleum Industry Press,2002.
[21]Nghiem LX,Li YK.Computation of multiphase equilibrium phenomena with an equation of state[J].Fluid Phase Equilibria,1984,17(1):77-95.
[22]施文,恒冠仁,郭尚平.二氧化碳—烃—水系统相平衡闪蒸计算方法研究[J].石油勘探与开发,1992,19(3):48-56.Shi Wen,Huan Guanren,Guo Shangping.Flash calculation for the phase equilibrium of a CO2–hydrocarbon–water system[J].Petroleum Exploration and Development,1992,19(3):48-56.
[23]Novasad Z.Composition and phase changes in testing and producing retrograde gas wells[J].SPE Reservoir Engineering,1996,11(4):231-235.
[2]孙杨,杜志敏,孙雷,汤勇,潘毅.CO2的埋存与提高天然气采收率的相行为研究[J].天然气工业,2012,32(5):39-42.Sun Yang,Du Zhimin,Sun Lei,Tang Yong,Pan Yi.Phase behavior of CO2 sequestration and the enhanced natural gas recovery[J].Natural Gas Industry,2012,32(5):39-42.
[3]孙扬,催飞飞,孙雷,杜志敏,汤勇.重力分异和非均质性对天然气藏CO2埋存的影响——以中国南方气藏为例[J].天然气工业,2014,34(8):82-86.Sun Yang,Cui Feifei,Sun Lei,Du Zhimin,Tang Yong.Infl unence of gravity differentiation and heterogeneity on CO2 sequestration in gas reservoirs:A case of the XC Gas Reservoir in South China[J].Natural Gas Industry,2014,34(8):82-86.
[4]朱忠谦.牙哈凝析气藏二次注气抑制反凝析机理及相态特征[J].天然气工业,2015,35(5):60-65.Zhu Zhongqian.Mechanism and phase behavior of retrograde condensation inhibition by secondary gas injection in the Yaha condensate gas reservoir[J].Natural Gas Industry,2015,35(5):60-65.
[5]汤勇,孙雷,李士伦,孙良田,杜志敏,刘利.用相平衡理论评价注气吞吐消除凝析气井反凝析污染机理[J].天然气工业,2005,25(12):83-86.Tang Yong,Sun Lei,Li Shilun,Sun Liangtian,Du Zhimin,Liu Li.Evaluating mechanism of huff and puff to eliminate retrograde condensate pollution for condensate wells by phase equilibrium theory[J].Natural Gas Industry,2005,25(12):83-86.
[6]汤勇,尹鹏,汪勇,孙博,侯大力.CO2混相驱的可行性评价[J].西南石油大学学报:自然科学版,2014,36(2):133-138.Tang Yong,Yin Peng,Wang Yong,Sun Bo,Hou Dali.Feasibility assessment of the CO2 miscible flooding process[J].Journal of Southwest Petroleum University:Science&Technology Edition,2014,36(2):133-138.
[7]肖朴夫,杨正明,王学武,戴兴星.室内注二氧化碳微观驱油机理研究[J].西南石油大学学报:自然科学版,2015,37(4):161-165.Xiao Pufu,Yang Zhengming,Wang Xuewu,Dai Xingxing.A laboratory study on the micro mechanism of oil displacement with CO2fl ooding[J].Journal of Southwest Petroleum University:Science&Technology Edition,2015,37(4):161-165.
[8]郭平,景莎莎,彭彩珍.气藏提高采收率技术及其对策[J].天然气工业,2014,34(2):48-55.Guo Ping,Jing Shasha,Peng Caizhen.Technology and countermeasures for gas recovery enhancement[J].Natural Gas Industry,2014,34(2):48-55.
[9]Narinesingh J,Alexander D.CO2 enhanced gas recovery and geologic sequestration in condensate reservoir:A simulation study of the effects of injection pressure on condensate recovery from reservoir and CO2 storage effi ciency[C]//12th International Conference on Greenhouse Gas Control Technologies(GHGT-12),5-9 October2014,Austin,Texas,USA.DOI:http://dx.doi.org/10.1016/j.egypro.2014.11.334.
[10]Shtepani E.CO2 sequestration in depleted gas/condensate reservoirs[C]//SPE Annual Technical Conference and Exhibition,24-27 September 2006,San Antonio,Texas,USA.DOI:http://dx.doi.org/10.2118/102284-MS.
[11]Yuan Chengwu,Zhang Zhong,Liu Kaijian.Assessment of the recovery and front contrast of CO2 EOR and sequestration in a new gas condensate reservoir by compositional simulation and seismic modeling[J].Fuel,2015,142(1):81-86.
[12]侯大力,高黎惠,刘浩成,张梅珠,崔飞飞.近临界态凝析气藏地层流体特殊相态行为[J].天然气工业,2013,33(11):68-73.Hou Dali,Gao Lihui,Liu Haocheng,Zhang Meizhu,Cui Feifei.Dynamic phase behavior of near-critical condensate gas reservoir fl uids[J].Natural Gas Industry,2013,33(11):68-73.
[13]王长权,汤勇,杜志敏,陈亮,孙杨,潘毅,等.含水凝析气相态特征及非平衡压降过程产液特征[J].石油学报,2013,34(4):740-746.Wang Changquan,Tang Yong,Du Zhimin,Chen Liang,Sun Yang,Pan Yi,et al.Phase behaviors of condensate gas with vaporous water and liquid production characteristics in a non-equilibrium pressure drop process[J].Acta Petrolei Sinica,2013,34(4):740-746.
[14]石德佩,孙雷,刘建仪,常志强,李相方.高温高压含水凝析气相态特征研究[J].天然气工业,2006,26(3):95-97.Shi Depei,Sun Lei,Liu Jianyi,Chang Zhiqiang,Li Xiangfang.Phase behavior of wet condensate gas at high temperature and pressure[J].Natural Gas Industry,2006,26(3):95-97.
[15]刘志斌,刘道杰,田中敬.高温高压凝析气藏物质平衡方程的建立——考虑气藏气相水蒸气含量及岩石颗粒的弹性膨胀作用[J].天然气工业,2011,31(7):37-39.Liu Zhibin,Liu Daojie,Tian Zhongjing.Establishment of material balance equation of HPHT gas condensate reservoirs:Taking into account the water vapor content of gas phase and the elastic expansion of rock particles[J].Natural Gas Industry,2011,31(7):37-39.
[16]汤勇,杜志敏,孙雷,刘伟,陈祖华.CO2在地层水中溶解对驱油过程的影响[J].石油学报,2011,3(2):311-314.Tang Yong,Du Zhimin,Sun Lei,Liu Wei,Chen Zuhua.Infl uence of CO2 dissolving in formation water on CO2 fl ooding process[J].Acta Petrolei Sinica,2011,32(2):311-314.
[17]Turta AT,Sim SSK,Singhal AK,Hawkins BF.Basic investigations on enhanced gas recovery by gas-gas displacement[J].Journal of Canadian Petroleum Technology,2008,47(10):39-44.
[18]Juanes R,Spiteri EJ,Orr Jr FM,Blunt MJ.Impact of relative permeability hysteresis on geological CO2 storage[J].Water Resources Research,2006,42(12):395-397.
[19]Kokal S,Al-Dokhi M,Sayegh S.Phase behavior of a gas-condensate/water system[J].SPE Reservoir Evaluation&Engineering,2003,6(6):412-420.
[20]郭天民.多元汽-液平衡和精馏[M].北京:石油工业出版社,2002.Guo Tianmin.Multicomponent vapor-liquid phase equilibrium and distillation[M].Beijing:Petroleum Industry Press,2002.
[21]Nghiem LX,Li YK.Computation of multiphase equilibrium phenomena with an equation of state[J].Fluid Phase Equilibria,1984,17(1):77-95.
[22]施文,恒冠仁,郭尚平.二氧化碳—烃—水系统相平衡闪蒸计算方法研究[J].石油勘探与开发,1992,19(3):48-56.Shi Wen,Huan Guanren,Guo Shangping.Flash calculation for the phase equilibrium of a CO2–hydrocarbon–water system[J].Petroleum Exploration and Development,1992,19(3):48-56.
[23]Novasad Z.Composition and phase changes in testing and producing retrograde gas wells[J].SPE Reservoir Engineering,1996,11(4):231-235.