低渗透油藏中不同压裂注采井网非稳态产量计算分析
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摘要
在井网压裂基础上进行注水,可以有效改善流场,增大泄油面积,是开发低渗透油藏的重要手段。快速准确预测低渗透油藏注水开发产量可以为开发优化设计奠定基础,但低渗透油藏注水开发呈现非稳态、非线性渗流特征,基于达西定律形成的油藏工程方法并不适用。本次研究通过流场分析,来划分等效流动单元,并在此基础上考虑了油水两相渗流启动压力梯度,采用流线积分法建立了不同压裂注采井网的水驱非稳态产量解析计算方法。与物理模拟及数值模拟相比,计算方法更简单,计算速度更快,可以为低渗透油藏压裂注采方式优选及注水开发对策制定提供手段。采用本方法计算并剖析了启动压力梯度、压裂注采方式及裂缝长度对油井生产动态的影响,结果表明:启动压力梯度增大了渗流阻力,与不考虑启动压力梯度相比,油井产量更低;受流动单元控制,不同压裂注采方式的增产效果及见水时间完全不同,同时压裂注采方式的增产效果最好,能够增产3.1倍,但见水时间仅为24个月;随着压裂缝长增加,油井产量越高,但当缝长超过最佳长度,增油效果不明显。
Waterflooding in fractured reservoirs,an important way to develop low permeability reservoirs,can effectively improve the flow field effectiveness and increase oil discharge area. Rapid and accurate prediction of production of low permeability reservoirs with water injection can establish a foundation for optimal design of development. However,the flow field of water injecting into low permeability reservoirs presents unsteady and nonlinear flow characteristics,so the calculation methods based on Darcy's law are not applicable. After the analysis of flow fields,the equivalent flow units are divided. Taking the threshold pressure gradient of oil-water two-phase flow into consideration,we established the analytical calculation method for unsteady oil production with injection in different fracturing modes,based on the flow line integral method. And the method is simpler and faster compared with physical and numerical simulations,so it is applicable for optimizing fracturing injection and production well patterns and water injection development strategies in low permeability reservoirs. Besides,this method was used to calculate and analyze the effects of threshold pressure gradient,fracturing injection and production methods and fracture lengths on the productivity of oil wells. The results show that( 1) the greater threshold pressure gradient leads to larger seepage resistance,so the well productivity is lower than that without considering the threshold pressure gradient;( 2) the well productivity is controlled by flow units,so with different fracturing injection and production modes,the effects of production increase and the time of water breakthrough are completely different. Although the increase of production with simultaneous fracturing injection and production is the best,being 3.1 times that of other modes,the water breakthrough time is just 24 months;( 3) with the increase of fracture length,the oil production increases,whereas the effect of increased oil production is not obvious any more when the fracture length ex-ceeds the optimum length.
Waterflooding in fractured reservoirs,an important way to develop low permeability reservoirs,can effectively improve the flow field effectiveness and increase oil discharge area. Rapid and accurate prediction of production of low permeability reservoirs with water injection can establish a foundation for optimal design of development. However,the flow field of water injecting into low permeability reservoirs presents unsteady and nonlinear flow characteristics,so the calculation methods based on Darcy's law are not applicable. After the analysis of flow fields,the equivalent flow units are divided. Taking the threshold pressure gradient of oil-water two-phase flow into consideration,we established the analytical calculation method for unsteady oil production with injection in different fracturing modes,based on the flow line integral method. And the method is simpler and faster compared with physical and numerical simulations,so it is applicable for optimizing fracturing injection and production well patterns and water injection development strategies in low permeability reservoirs. Besides,this method was used to calculate and analyze the effects of threshold pressure gradient,fracturing injection and production methods and fracture lengths on the productivity of oil wells. The results show that( 1) the greater threshold pressure gradient leads to larger seepage resistance,so the well productivity is lower than that without considering the threshold pressure gradient;( 2) the well productivity is controlled by flow units,so with different fracturing injection and production modes,the effects of production increase and the time of water breakthrough are completely different. Although the increase of production with simultaneous fracturing injection and production is the best,being 3.1 times that of other modes,the water breakthrough time is just 24 months;( 3) with the increase of fracture length,the oil production increases,whereas the effect of increased oil production is not obvious any more when the fracture length ex-ceeds the optimum length.
引文
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[14]冯文光.非达西低速渗流的研究现状与展望[J].石油勘探与开发,1986,13(4):76-80.Feng Wenguang.Progress of studies on the mechanism ofnon-Darcy low-velocity fluid flow[J].Petroleum Exploration and Development,1986,13(4):76-80.
[15]李爱芬,刘敏,张少辉,等.特低渗透油藏渗流特征实验研究[J].西安石油大学学报(自然科学版),2008,23(2):35-40.Li Aifen,Liu Min,Zhang Shaohui,et al.Experimental study on the percolation characteristic of extra low-permeability reservoir[J].Journal of Xi’an Shiyou Univeristy(Natural Science Edition),2008,23(2):35-40.
[16]陈汶滨,赵明,蔡明俊,等.基于指标特征模型的油藏注水开发效果定量化评价[J].石油学报,2016,37(2):80-86.Chen Wenbing,Zhao Ming,Cai Mingjun,et al.Quantitative evaluation of reservoir water-flooding development effect based on index characteristic model[J].Acta Petrolei Sinica,2016,37(2):80-86.
[17]时宇,杨正明,黄延章,等.低渗透储层非线性流模型研究[J].石油学报,2009,30(5):731-734.Shi Yu,Yang Zhengming,Huang Yanzhang,et al.Study on non-linear seepage flow model for low-permeability reservoir[J].Acta petrolei sinica,2009,30(5):731-734.
[18]朱明,吴晓东,韩国庆,等.多分支井电模拟试验研究[J].石油天然气学报,2012,35(6):90-93.Zhu Ming,Wu Xiaodong,Han Guoqing,et al.Experimental research of electric analogy for multi-lateral wells[J].Journal of Oil and Gas Technology,2012,35(6):90-93.
[19]郝明强,王晓冬,胡永乐.压敏性特低渗透油藏压裂水平井产能计算[J].中国石油大学报自然科学版,2011,35(6):99-104.Hao Mingqiang,Wang Xiaodong,Hu Yongle.Productivity calculation of multi-fractured horizontal well in ultra-low permeability pressuresensitive reservoirs[J].Journal of China University of Petroleum Edition of Natural Sciences,2011,35(6):99-104.
[20]徐庆岩,杨正明,何英,等.超低渗透油藏非线性渗流数值模拟[J].深圳大学学报理工版,2012,29(6):504-508.Xu Qingyan,Yang Zhengming,He Ying,et al.Numerical simulation of nonlinear seepage in super-low permeability reservoirs[J].Journal of Shenzhen University Science and Engineering,2012,29(6):504-508.
[21]曲占庆,张琪,吴志民,等.水平井压裂产能电模拟实验研究[J].油气地质与采收率,2006,13(3):53-55.Qu Zhanqing,Zhang Qi,Wu Zhimin,et al.Experimental research on electric analogy of the productivity of fractured horizontal well[J].Petroleum Geology and Recovery Efficiency,2006,13(3):53-55.
[22]林飞,欧阳传湘,李春颖,等.低渗透油藏注水开发调整方案数值模拟研究[J].当代化工,2016,45(3):549-551.Lin Fei,Ou Yang Chuanxiang,Li Chunying,et al.Numerical simulation on adjustment scheme of water injection development of low permeability reservoir[J],Contemporary Chemical Industry,2016,45(3):549-551.
[23]杨正明,刘先贵,孙长艳,等.低渗透油藏产量递减规律及水驱特征曲线[J].石油勘探与开发,2000,27(3):55-63.Yang Zhengming,Liu Xiangui,Sun Changyan,et al.Production decline law and water drive characteristic curves in low permeability reservoirs[J].Petroleum Exploration and Development,2000,27(3):55-63.
[24]计秉玉,王春艳,李莉,等.低渗透储层井网与压裂整体设计中的产量计算[J].石油学报,2009,30(4):578-582.Ji Bingyu,Wang Chuanyan,Li Li,et al.Calculation method for production rate of rectangular well pattern and fracturing integration production mode in low-permeability reservoir[J].ACTA PETROLEI SINICA,2009,30(4):578-582.
[25]蒲军,刘传喜,尚根华.基于流线积分法的面积井网注水开发非稳态产量计算模型[J].西南石油大学学报(自然科学版),2016,38(5):97-106.Pu Jun,Liu Chuanxi,Shang Genhua.Non-steady water-flooding production model of areal well pattern based on flow line integral method[J],Journal of Southwest Petroleum University(Science&Technology Edition),2016,38(5):97-106.
[26]李晓平.地下油气渗流力学[M].北京:石油工业出版社,2008:89-92.Li Xiaoping.Seepage mechanics of underground oil&gas[M]Beijing:Petroleum Industry Press,2008:89-92.
[2]李南,程林松,陈泓全,等.超低渗透油藏注水方式研究[J].油气地质与采收率,2012,19(4):78-80.Li Nan,Chen Linsong,Chen Hongquan,et al.Study on water injection in ultra low permeability reservoir[J].Petroleum Geology and Recovery Efficiency,2012,19(4):78-80.
[3]王文环,彭缓缓,李光泉,等.大庆低渗透油藏注水动态裂缝开启机理及有效调整对策[J].石油与天然气地质,2015,36(5):842-847.Wang Wenhuan,Peng Huanhuan,Li Guangquan,et al,Opening mechanism of dynamic fractures caused by water injection and effective adjustments in low permeability reservoirs Daqing oilfield in Songliao Basin[J].Oil&Gas Geology,2015,36(5):842-847.
[4]苏玉亮,吴春新,高丽,等.特低渗透油藏水驱油注水界限的确定[J].石油钻探技术,2012,40(2):82-86.Su Yuliang,Wu Chunxin,Gao Li,et al.Determination of waterflooding limits for driving an ultra-Low permeability reservoir[J].Petroleum Drilling Techniques,2012,40(2):82-86.
[5]万文胜,杜军社,秦旭升,等.低渗透注水开发砂岩油藏合理井网井距的确定方法[J].新疆石油天然气,2007,3(1):56-59.Wan Wensheng,Du Junshe,Qin Xusheng,et al.Determination method of reasonable well pattern and spacing for injection sandstone reservoirs of low permeability[J].Xinjiang Oil&Gas,2007,3(1):56-59.
[6]李亮,胡建国,阎纪辉,等.超前注水是低渗透油田开发的重要途径-以长庆油田三叠系延长组油藏为例[J].新疆石油地质,2001,22(3):232-234.Li Liang,Hu Jianguo,Yan Jihui,et al.Advance water injection-an important appraoch for development of low permeability pools—an example from Yanchang formation reservoir in Changqing oilfield[J].Xinjiang Petroleum Geology,2001,22(3):232-234.
[7]刘立虎.超前注水在特低渗透油田中的应用—以吴起油田为例[J].非常规油气,2018,5(1):86-93.Liu Lihu.Advanced water injection implemented in extremely low permeability oilfield-taking Wuqi oilfield as an example[J].Unconventional Oil&Gas,2018,5(1):86-93.
[8]熊维亮,潘增耀,王斌,等.特低渗透油田裂缝发育区剩余油分布及调整技术[J].石油勘探与开发,1999,26(5):46-49.Xiong Weiliang,Pan Zengyao,Wang Bin,et al,Distribution of remaining oil and its adjustment in fracture-developed areas of ultra-lowpermeability oil fields[J].Petroleum Exploration and Development,1999,26(5):46-49.
[9]刘冬旭,李啸天,刘健,等.低渗透介质启动压力梯度的介观机理研究[J].工程热物理学报,2017,38(4):787-791.Liu Dongxu,Li Xiaotian,Liu Jian,et al.Mesoscopicmechanism of threshold pressure gradient in low permeability porous media[J].Journal of Engineering Thermophysics,2017,38(4):787-791.
[10]熊伟,雷群,刘先贵,等.低渗透油藏拟启动压力梯度[J].石油勘探与开发,2009,36(2):232-236.Xiong Wei,Lei Qun,Liu Xiangui,et al.Pseudo threshold pressure gradient to flow for low permeability reservoirs[J].Petroleum Exploration and Development,2009,36(2):232-236.
[11]刘丽,孙志刚,顾辉亮.低渗透非均质砂岩油藏启动压力梯度研究[J].科学技术与工程,2015,15(3):66-70.Liu Li,Sun Zhigang,Gu Huiliang.Study on starting pressure gradient for low permeabilityheterogeneous sandstone reservoir[J].Science Technology and Engineering,2015,15(3):66-70.
[12]李玉丹,董平川,张荷,等.低渗透油藏渗透率及启动压力梯度应力敏感性分析[J].油气地质与采收率,2016,23(6):57-63.Li Yudan,Dong Pingchuan,Zhang He,et al.Stress sensitivity analysis of permeability and threshold pressuregradient in low-permeability reservoir[J].Petroleum Geology and Recovery Efficiency,2016,23(6):57-63.
[13]黄延章.低渗透油层非线性渗流特征[J].特种油气藏,1997,4(1):9-14.Huang Yanzhang.Nonlinear percolation feature in low permeability reservoir[J].Special Oil and Gas Reservoirs,1997,4(1):9-14.
[14]冯文光.非达西低速渗流的研究现状与展望[J].石油勘探与开发,1986,13(4):76-80.Feng Wenguang.Progress of studies on the mechanism ofnon-Darcy low-velocity fluid flow[J].Petroleum Exploration and Development,1986,13(4):76-80.
[15]李爱芬,刘敏,张少辉,等.特低渗透油藏渗流特征实验研究[J].西安石油大学学报(自然科学版),2008,23(2):35-40.Li Aifen,Liu Min,Zhang Shaohui,et al.Experimental study on the percolation characteristic of extra low-permeability reservoir[J].Journal of Xi’an Shiyou Univeristy(Natural Science Edition),2008,23(2):35-40.
[16]陈汶滨,赵明,蔡明俊,等.基于指标特征模型的油藏注水开发效果定量化评价[J].石油学报,2016,37(2):80-86.Chen Wenbing,Zhao Ming,Cai Mingjun,et al.Quantitative evaluation of reservoir water-flooding development effect based on index characteristic model[J].Acta Petrolei Sinica,2016,37(2):80-86.
[17]时宇,杨正明,黄延章,等.低渗透储层非线性流模型研究[J].石油学报,2009,30(5):731-734.Shi Yu,Yang Zhengming,Huang Yanzhang,et al.Study on non-linear seepage flow model for low-permeability reservoir[J].Acta petrolei sinica,2009,30(5):731-734.
[18]朱明,吴晓东,韩国庆,等.多分支井电模拟试验研究[J].石油天然气学报,2012,35(6):90-93.Zhu Ming,Wu Xiaodong,Han Guoqing,et al.Experimental research of electric analogy for multi-lateral wells[J].Journal of Oil and Gas Technology,2012,35(6):90-93.
[19]郝明强,王晓冬,胡永乐.压敏性特低渗透油藏压裂水平井产能计算[J].中国石油大学报自然科学版,2011,35(6):99-104.Hao Mingqiang,Wang Xiaodong,Hu Yongle.Productivity calculation of multi-fractured horizontal well in ultra-low permeability pressuresensitive reservoirs[J].Journal of China University of Petroleum Edition of Natural Sciences,2011,35(6):99-104.
[20]徐庆岩,杨正明,何英,等.超低渗透油藏非线性渗流数值模拟[J].深圳大学学报理工版,2012,29(6):504-508.Xu Qingyan,Yang Zhengming,He Ying,et al.Numerical simulation of nonlinear seepage in super-low permeability reservoirs[J].Journal of Shenzhen University Science and Engineering,2012,29(6):504-508.
[21]曲占庆,张琪,吴志民,等.水平井压裂产能电模拟实验研究[J].油气地质与采收率,2006,13(3):53-55.Qu Zhanqing,Zhang Qi,Wu Zhimin,et al.Experimental research on electric analogy of the productivity of fractured horizontal well[J].Petroleum Geology and Recovery Efficiency,2006,13(3):53-55.
[22]林飞,欧阳传湘,李春颖,等.低渗透油藏注水开发调整方案数值模拟研究[J].当代化工,2016,45(3):549-551.Lin Fei,Ou Yang Chuanxiang,Li Chunying,et al.Numerical simulation on adjustment scheme of water injection development of low permeability reservoir[J],Contemporary Chemical Industry,2016,45(3):549-551.
[23]杨正明,刘先贵,孙长艳,等.低渗透油藏产量递减规律及水驱特征曲线[J].石油勘探与开发,2000,27(3):55-63.Yang Zhengming,Liu Xiangui,Sun Changyan,et al.Production decline law and water drive characteristic curves in low permeability reservoirs[J].Petroleum Exploration and Development,2000,27(3):55-63.
[24]计秉玉,王春艳,李莉,等.低渗透储层井网与压裂整体设计中的产量计算[J].石油学报,2009,30(4):578-582.Ji Bingyu,Wang Chuanyan,Li Li,et al.Calculation method for production rate of rectangular well pattern and fracturing integration production mode in low-permeability reservoir[J].ACTA PETROLEI SINICA,2009,30(4):578-582.
[25]蒲军,刘传喜,尚根华.基于流线积分法的面积井网注水开发非稳态产量计算模型[J].西南石油大学学报(自然科学版),2016,38(5):97-106.Pu Jun,Liu Chuanxi,Shang Genhua.Non-steady water-flooding production model of areal well pattern based on flow line integral method[J],Journal of Southwest Petroleum University(Science&Technology Edition),2016,38(5):97-106.
[26]李晓平.地下油气渗流力学[M].北京:石油工业出版社,2008:89-92.Li Xiaoping.Seepage mechanics of underground oil&gas[M]Beijing:Petroleum Industry Press,2008:89-92.