复杂裂缝中CO_2流体携砂规律的数值模拟
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摘要
基于计算流体力学(CFD)方法,建立了适用于模拟CO_2流体和支撑剂两相流动规律的固液两相流数学模型,并利用有限体积法进行求解,分析了泵注速度、砂比、支撑剂密度和粒径以及裂缝复杂程度对支撑剂在复杂裂缝中运移规律的影响。结果表明:支撑剂流入分支缝的方式主要包括主裂缝在分支缝缝口处形成砂堤后依靠重力作用滚入二级缝中,或是依靠携砂液的流速携带至分支缝内;泵注速度、支撑剂目数与平衡高度呈负相关,且泵注速度与平衡时间呈负相关、支撑剂目数与平衡时间呈正相关;砂比、支撑剂密度与平衡高度呈正相关,与平衡时间呈负相关;裂缝的级数越多,达到平衡所需要的时间越长,复杂裂缝中支撑剂在各分支缝节点处出现转向运移,且主要沉降在离主裂缝较近的二级缝中;由于三级缝较窄,进入三级缝深部的支撑剂量较少,且各分支缝中的砂堤高度小于主裂缝中的砂堤高度。
The mathematical model of liquid-solid two-phase flow suitable for simulating two-phase flow of CO_2 fluid and proppant is established based on computational fluid dynamics(CFD),and it is solved by using finite volume method.The influences of injection rate,sand ratio,proppant density,proppant size and fracture complexity on the proppant migration law in complex fractures were analyzed.The results show that the ways of proppant flowing into the branch fractures mainly includes the proppant which forms sand dike at the inlet of branch fracture rolling into the branch fracture due to gravity and proppant being carried into the branch fractures by sand carrying fluid.Injection rate and proppant particle size are negatively correlated with equilibrium height of sand dike,injection rate is negatively correlated with equilibrium time of sand dike,andproppant particle size is positively correlated with equilibrium time of sand dike.Sand ratio and proppant density are positively correlated with equilibrium height of sand dike,and negatively correlated with equilibrium time of sand dike.The more the series of fractures,the longer it takes to achieve equilibrium of sand dike.In complex fractures,proppant migration direction will be changed at the joint of each branch fracture,and proppant mainly settles in the secondary fracture close to the main fracture.Due to the small width of grade 3 fractures,the amount of proppant entering the deep part of the grade 3 fractures is less,and the height of sand dike in each branch fracture is less than that in main fracture.
The mathematical model of liquid-solid two-phase flow suitable for simulating two-phase flow of CO_2 fluid and proppant is established based on computational fluid dynamics(CFD),and it is solved by using finite volume method.The influences of injection rate,sand ratio,proppant density,proppant size and fracture complexity on the proppant migration law in complex fractures were analyzed.The results show that the ways of proppant flowing into the branch fractures mainly includes the proppant which forms sand dike at the inlet of branch fracture rolling into the branch fracture due to gravity and proppant being carried into the branch fractures by sand carrying fluid.Injection rate and proppant particle size are negatively correlated with equilibrium height of sand dike,injection rate is negatively correlated with equilibrium time of sand dike,andproppant particle size is positively correlated with equilibrium time of sand dike.Sand ratio and proppant density are positively correlated with equilibrium height of sand dike,and negatively correlated with equilibrium time of sand dike.The more the series of fractures,the longer it takes to achieve equilibrium of sand dike.In complex fractures,proppant migration direction will be changed at the joint of each branch fracture,and proppant mainly settles in the secondary fracture close to the main fracture.Due to the small width of grade 3 fractures,the amount of proppant entering the deep part of the grade 3 fractures is less,and the height of sand dike in each branch fracture is less than that in main fracture.
引文
[1] 贾承造,邹才能,李建忠,等.中国致密油评价标准、主要类型、基本特征及资源前景[J].石油学报,2012,33(3):343-350.JIA Chengzao,ZOU Caineng,LI Jianzhong,et al.Assessment criteria,main types,basic features and resource prospects of the tight oil in China[J].Acta Petrolei Sinica,2012,33(3):343-350.
[2] 赵立强,牟媚,罗志锋,等.中国致密油储层改造理念及技术展望[J].西南石油大学学报(自然科学版),2016,38(6):111-118.ZHAO Liqiang,MOU Mei,LUO Zhifeng,et al.The outlook for China's tight oil reservoir stimulation concept and technology[J].Journal of Southwest Petroleum University(Science & Technology Edition),2016,38(6):111-118.
[3] 刘合,王峰,张劲.二氧化碳干法压裂技术:应用现状与发展趋势[J].石油勘探与开发,2015,41(4):466-472.LIU He,WANG Feng,ZHANG Jin,et al.Fracturing with carbon dioxide:application status and development trend[J].Petroleum Exploration and Development,2015,41(4):466-472.
[4] 赵金洲,任岚,沈骋.页岩气储层缝网压裂理论与技术研究新进展[J].天然气工业,2018,38(3):1-14.ZHAO Jinzhou,REN Lan,SHEN Cheng,et al.Latest research progresses in network fracturing theories and technologies for shale gas reservoirs[J].Natural Gas Industry,2018,38(3):1-14.
[5] 徐林静,张士诚,马新仿.胍胶压裂液对储集层渗透率的伤害特征[J].新疆石油地质,2016,37(4):456-459.XU Linjing,ZHANG Shicheng,MA Xinfang.Characteristics of damage of guar fracturing fluid to reservoir permeability[J].Xinjiang Petroleum Geology,2016,37(4):456-459.
[6] 刘建坤,郭和坤,吴春方,等.致密储层压裂液稠化剂损害实验评价方法[J].大庆石油地质与开发,2013,32(5):98-103.LIU Jiangkun,GUO Hekun,WU Chunfang,et al.Evaluation method of the damage experiment for the fracturing-fluid thickener in tight reservoirs[J].Petroleum Geology and Oilfield Development in Daqing,2013,32(5):98-103.
[7] HAIMSON B C,ZHAO Z L.Effect of borehole size and pressurization rate on hydraulic fracturing breakdown pressure[C].The 32nd U.S.Symposium on Rock Mechanics.Norman,Oklahoma:American Rock Mechanics Association,1991:191-199.
[8] ITO T.Effect of pore pressure gradient on fracture initiation in fluid saturated porous media[J].Rock Engineering Fracture Mechanics,2008,75(7):1753-1762.
[9] 李根生,王海柱,沈忠厚,等.超临界CO2射流在石油工程中应用研究与前景展望[J].中国石油大学学报(自然科学版),2013,37(5):76-87.LI Gensheng,WANG Haizhu,SHEN Zhonghou,et al.Application investigations and prospects of supercritical carbon dioxide jet in petroleum engineering[J].Journal of China University of Petroleum(Edition of Natural Science),2013,37(5):76-87.
[10] 肖博,蒋廷学,张士诚.垂直裂缝内液体二氧化碳携砂性能的数值模拟[J].科学技术与工程,2018,18(12):186-190.XIAO Bo,JIANG Tingxue,ZHANG Shicheng.Numerical simluation on proppant transport of liquid carbon dioxide in vertical fracture[J].Science Technology and Engineering,2018,18(12):186-190.
[11] DANESHY A A.Numerical solution of sand transport in hydraulic fracturing[J].Journal of Petroleum Technology,1978,30(1):132-140.
[12] UNWIN A T,HAMMOND P S.Computer simulations of proppant transport in a hydraulic fracture[C].SPE 29649,1995.
[13] MOBBS A T,HAMMOND P S.Computer simulations of proppant transport in a hydraulic fracture[C].SPE 69212,2001.
[14] LIU Y J.Settling and Hydrodynamic Retardation of Proppants in Hydraulic Fractures[D].Texas:The University of Texas,2007.
[15] 张涛,郭建春,刘伟.清水压裂中支撑剂输送沉降行为的CFD模拟[J].西南石油大学学报(自然科学版),2014,36(1):74-82.ZHANG Tao,GUO Jianchun,LIU Wei.CFD simulation of proppant transportation and settling in water fracture treatments[J].Journal of Southwest Petroleum University(Science & Technology Edition),2014,36(1):74-82.
[16] 温庆志,段晓飞,战永平,等.支撑剂在复杂缝网中的沉降运移规律研究[J].西安石油大学学报(自然科学报),2016,31(1):79-84.WEN Qingzhi,DUAN Xiaofei,ZHAN Yongping,et al.Study on settlement and migration law of proppant in complex fracture network[J].Journal of Xi'an Shiyou University(Natural Science Edition),2016,31(1):79-84.
[17] SUN Baojiang,WANG Jintang,WANG Zhiyuan,et al.Calculation of proppant-carrying flow in supercritical carbon dioxide fracturing fluid[J].Journal of Natural Gas Science & Engineering,2018,166:420-432.
[18] 朱红钧.FLUENT CFD工程仿真实战指南[M].北京:人民邮电出版社,2014:40-74.ZHU Hongjun.FLUENT CFD Engineering Simulation Guide[M].Beijing:Posts and Telecommunications Press,2014:40-74.
[19] ISHII M,MISHIMA K.Two-fluid model and hydrodynamic constitutive relations[J].Nuclear Engineering and Design,1984,82(84):107-126.
[20] GIDASPOW D.Multiphase Flow and Fluidization:Continuum and Kinetic Theory Descriptions[M].Boston:Academic Press,1994:457-467.
[21] BENYAHIA S,SYAMLAL M,O'BRIEN T J.Evaluation of boundary conditions used to model dilute,turbulent gas/solids flows in a pipe[J].Powder Technology,2005,156(2):62-72.
[22] 叶亮,邹雨时,赵倩云,等.致密砂岩储层CO2压裂裂缝扩展实验研究[J].石油钻采工艺,2018,40(3):361-368.YE Liang,ZOU Yushi,ZHAO Qianyun,et al.Experiment research on the CO2 fracturing fracture propagation laws of tight sandstone[J].Oil Drilling & Production Technology,2018,40(3):361-368.
[2] 赵立强,牟媚,罗志锋,等.中国致密油储层改造理念及技术展望[J].西南石油大学学报(自然科学版),2016,38(6):111-118.ZHAO Liqiang,MOU Mei,LUO Zhifeng,et al.The outlook for China's tight oil reservoir stimulation concept and technology[J].Journal of Southwest Petroleum University(Science & Technology Edition),2016,38(6):111-118.
[3] 刘合,王峰,张劲.二氧化碳干法压裂技术:应用现状与发展趋势[J].石油勘探与开发,2015,41(4):466-472.LIU He,WANG Feng,ZHANG Jin,et al.Fracturing with carbon dioxide:application status and development trend[J].Petroleum Exploration and Development,2015,41(4):466-472.
[4] 赵金洲,任岚,沈骋.页岩气储层缝网压裂理论与技术研究新进展[J].天然气工业,2018,38(3):1-14.ZHAO Jinzhou,REN Lan,SHEN Cheng,et al.Latest research progresses in network fracturing theories and technologies for shale gas reservoirs[J].Natural Gas Industry,2018,38(3):1-14.
[5] 徐林静,张士诚,马新仿.胍胶压裂液对储集层渗透率的伤害特征[J].新疆石油地质,2016,37(4):456-459.XU Linjing,ZHANG Shicheng,MA Xinfang.Characteristics of damage of guar fracturing fluid to reservoir permeability[J].Xinjiang Petroleum Geology,2016,37(4):456-459.
[6] 刘建坤,郭和坤,吴春方,等.致密储层压裂液稠化剂损害实验评价方法[J].大庆石油地质与开发,2013,32(5):98-103.LIU Jiangkun,GUO Hekun,WU Chunfang,et al.Evaluation method of the damage experiment for the fracturing-fluid thickener in tight reservoirs[J].Petroleum Geology and Oilfield Development in Daqing,2013,32(5):98-103.
[7] HAIMSON B C,ZHAO Z L.Effect of borehole size and pressurization rate on hydraulic fracturing breakdown pressure[C].The 32nd U.S.Symposium on Rock Mechanics.Norman,Oklahoma:American Rock Mechanics Association,1991:191-199.
[8] ITO T.Effect of pore pressure gradient on fracture initiation in fluid saturated porous media[J].Rock Engineering Fracture Mechanics,2008,75(7):1753-1762.
[9] 李根生,王海柱,沈忠厚,等.超临界CO2射流在石油工程中应用研究与前景展望[J].中国石油大学学报(自然科学版),2013,37(5):76-87.LI Gensheng,WANG Haizhu,SHEN Zhonghou,et al.Application investigations and prospects of supercritical carbon dioxide jet in petroleum engineering[J].Journal of China University of Petroleum(Edition of Natural Science),2013,37(5):76-87.
[10] 肖博,蒋廷学,张士诚.垂直裂缝内液体二氧化碳携砂性能的数值模拟[J].科学技术与工程,2018,18(12):186-190.XIAO Bo,JIANG Tingxue,ZHANG Shicheng.Numerical simluation on proppant transport of liquid carbon dioxide in vertical fracture[J].Science Technology and Engineering,2018,18(12):186-190.
[11] DANESHY A A.Numerical solution of sand transport in hydraulic fracturing[J].Journal of Petroleum Technology,1978,30(1):132-140.
[12] UNWIN A T,HAMMOND P S.Computer simulations of proppant transport in a hydraulic fracture[C].SPE 29649,1995.
[13] MOBBS A T,HAMMOND P S.Computer simulations of proppant transport in a hydraulic fracture[C].SPE 69212,2001.
[14] LIU Y J.Settling and Hydrodynamic Retardation of Proppants in Hydraulic Fractures[D].Texas:The University of Texas,2007.
[15] 张涛,郭建春,刘伟.清水压裂中支撑剂输送沉降行为的CFD模拟[J].西南石油大学学报(自然科学版),2014,36(1):74-82.ZHANG Tao,GUO Jianchun,LIU Wei.CFD simulation of proppant transportation and settling in water fracture treatments[J].Journal of Southwest Petroleum University(Science & Technology Edition),2014,36(1):74-82.
[16] 温庆志,段晓飞,战永平,等.支撑剂在复杂缝网中的沉降运移规律研究[J].西安石油大学学报(自然科学报),2016,31(1):79-84.WEN Qingzhi,DUAN Xiaofei,ZHAN Yongping,et al.Study on settlement and migration law of proppant in complex fracture network[J].Journal of Xi'an Shiyou University(Natural Science Edition),2016,31(1):79-84.
[17] SUN Baojiang,WANG Jintang,WANG Zhiyuan,et al.Calculation of proppant-carrying flow in supercritical carbon dioxide fracturing fluid[J].Journal of Natural Gas Science & Engineering,2018,166:420-432.
[18] 朱红钧.FLUENT CFD工程仿真实战指南[M].北京:人民邮电出版社,2014:40-74.ZHU Hongjun.FLUENT CFD Engineering Simulation Guide[M].Beijing:Posts and Telecommunications Press,2014:40-74.
[19] ISHII M,MISHIMA K.Two-fluid model and hydrodynamic constitutive relations[J].Nuclear Engineering and Design,1984,82(84):107-126.
[20] GIDASPOW D.Multiphase Flow and Fluidization:Continuum and Kinetic Theory Descriptions[M].Boston:Academic Press,1994:457-467.
[21] BENYAHIA S,SYAMLAL M,O'BRIEN T J.Evaluation of boundary conditions used to model dilute,turbulent gas/solids flows in a pipe[J].Powder Technology,2005,156(2):62-72.
[22] 叶亮,邹雨时,赵倩云,等.致密砂岩储层CO2压裂裂缝扩展实验研究[J].石油钻采工艺,2018,40(3):361-368.YE Liang,ZOU Yushi,ZHAO Qianyun,et al.Experiment research on the CO2 fracturing fracture propagation laws of tight sandstone[J].Oil Drilling & Production Technology,2018,40(3):361-368.