燃爆诱导水力压裂多裂缝耦合起裂规律
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摘要
为了明确多相位裂缝组合下的应力干扰作用及其对后续水力压裂裂缝起裂压力的影响,基于原有预存单条诱导裂缝的应力场计算模型建立预存多条诱导裂缝的耦合应力场计算模型,分析诱导应力影响下的井周周向应力场变化规律,再结合断裂力学判据计算后续水力压裂预存裂缝的起裂压力,并对预存裂缝长度、相位、水平主应力差异系数及预存裂缝条数等4个因素对预存裂缝起裂压力的影响进行了分析。研究结果表明:(1)预存裂缝后近裂缝区域周向应力差明显增大,甚至出现水平主应力反转;(2)随新增预存裂缝长度增加,原预存裂缝起裂压力先增后降,在新增预存裂缝长度增加到原预存裂缝长度时,原预存裂缝起裂压力迅速降低,而后下降趋势变平缓;(3)高相位裂缝的起裂压力大于低相位裂缝的起裂压力;(4)随着裂缝条数的增加,新增预存裂缝起裂压力逐渐降低,但起裂压力差减小的趋势不明显;(5)多相位裂缝的应力干扰作用影响裂缝的起裂压力,较长高相位裂缝和较短低相位裂缝均有利于多相位裂缝的同时起裂;(6)多裂缝同步延伸会产生更为复杂的应力干扰作用,激发水力压裂复杂缝网的演化,实现均衡的压裂改造。结论认为,该研究成果可为燃爆诱导压裂射孔相位、诱导裂缝规模及后续水力压裂施工泵压等压裂施工设计提供理论指导。
For figuring out the stress interference of multiphase fracture combinations and its effect on the fracture initiation pressure of subsequent hydraulic fracturing, a calculation model for the coupled stress field with multiple induced fractures preexisted was established based on the calculation model for the stress field with single induced fracture preexisted, and the change laws of circumferential stress field around the wellbore under the effect of induced stress were analyzed. Then, the fracture initiation pressure of subsequent hydraulic fracturing was calculated according to the fracturing mechanics criterion. Finally, the effects of the length, phase, horizontal principal stress difference coefficient and quantity of preexisting fractures on its initiation pressure were analyzed. And the following research results were obtained. First, the circumferential stress difference in the area near the fractures behind the preexisting fractures increase greatly and even the horizontal principal stress is reversed. Second, as the length of new preexisting fractures increases, the initiation pressure of initial preexisting fractures rises first and then drops. And when the length of new preexisting fractures is equal to that of the initial preexisting fractures, the initiation pressure of initial preexisting fractures drops quickly first and then slowly. Third, the initiation pressure of high phase fractures is lower than that of low phase fractures. Fourth, with the increase of fracture quantity, the initiation pressure of new preexisting fractures drops gradually, but the decline trend of initiation pressure difference is not obvious. Fifth, the stress interference of multiphase fractures influences the fracture initiation pressure, and high-phase long fractures and low-phase short fractures are both favorable for the simultaneous initiation of multiphase fractures. Sixth, synchronous propagation of multiple fractures can generate more complicated stress interference and excite the evolution of hydraulic fracture network, so as to realize uniform fracturing stimulation. In conclusion, the research results can provide a theoretical guidance for the design of fracturing operation, e.g. perforation phase of blasting induced fracturing, scale of induced fractures, and pump pressure of subsequent hydraulic fracturing.
For figuring out the stress interference of multiphase fracture combinations and its effect on the fracture initiation pressure of subsequent hydraulic fracturing, a calculation model for the coupled stress field with multiple induced fractures preexisted was established based on the calculation model for the stress field with single induced fracture preexisted, and the change laws of circumferential stress field around the wellbore under the effect of induced stress were analyzed. Then, the fracture initiation pressure of subsequent hydraulic fracturing was calculated according to the fracturing mechanics criterion. Finally, the effects of the length, phase, horizontal principal stress difference coefficient and quantity of preexisting fractures on its initiation pressure were analyzed. And the following research results were obtained. First, the circumferential stress difference in the area near the fractures behind the preexisting fractures increase greatly and even the horizontal principal stress is reversed. Second, as the length of new preexisting fractures increases, the initiation pressure of initial preexisting fractures rises first and then drops. And when the length of new preexisting fractures is equal to that of the initial preexisting fractures, the initiation pressure of initial preexisting fractures drops quickly first and then slowly. Third, the initiation pressure of high phase fractures is lower than that of low phase fractures. Fourth, with the increase of fracture quantity, the initiation pressure of new preexisting fractures drops gradually, but the decline trend of initiation pressure difference is not obvious. Fifth, the stress interference of multiphase fractures influences the fracture initiation pressure, and high-phase long fractures and low-phase short fractures are both favorable for the simultaneous initiation of multiphase fractures. Sixth, synchronous propagation of multiple fractures can generate more complicated stress interference and excite the evolution of hydraulic fracture network, so as to realize uniform fracturing stimulation. In conclusion, the research results can provide a theoretical guidance for the design of fracturing operation, e.g. perforation phase of blasting induced fracturing, scale of induced fractures, and pump pressure of subsequent hydraulic fracturing.
引文
[1]李克明,张曦.高能复合射孔技术及应用[J].石油勘探与开发,2002,29(5):91-92.Li Keming&Zhang Xi.High energy combined perforation technique and its application[J].Petroleum Exploration and Development,2002,29(5):91-92.
[2]叶显军,张惠生,田国理.液体火药高能气体压裂技术研究和在深层油气藏中的应用[J].石油勘探与开发,2000,27(3):67-69.Ye Xianjun,Zhang Huisheng&Tian Guoli.The high energy gas fracturing technique of liquid explosive and its application in deep-seated oil and gas reservoirs[J].Petroleum Exploration and Development,2000,27(3):67-69.
[3]陈莉静,李宁,王俊奇.高能复合射孔爆生气体作用下预存裂缝起裂扩展研究[J].石油勘探与开发,2005,32(6):91-93.Chen Lijing,Li Ning&Wang Junqi.Initiation and extension of existing cracks under detonation gas loading in a high energy combined perforation[J].Petroleum Exploration and Development,2005,32(6):91-93.
[4]雷群,胥云,蒋廷学,丁云宏,王晓泉,卢海兵.用于提高低-特低渗透油气藏改造效果的缝网压裂技术[J].石油学报,2009,30(2):237-241.Lei Qun,Xu Yun,Jiang Tingxue,Ding Yunhong,Wang Xiaoquan&Lu Haibing."Fracture network"fracturing technique for improving post-fracturing performance of low and ultra-low permeability reserviors[J].Acta Petrolei Sinica,2009,30(2):237-241.
[5]周健,陈勉,金衍,张广清.多裂缝储层水力裂缝扩展机理试验[J].中国石油大学学报(自然科学版),2008,32(4):51-54.Zhou Jian,Chen Mian,Jin Yan&Zhang Guangqing.Experiment of propagation mechanism of hydraulic fracture in multi-fracture reservoir[J].Journal of China University of Petroleum(Edition of Natural Science),2008,32(4):51-54.
[6]Li Jia,Guo Boyun&Yin Feng.An analytical solution of fractureinduced stress and its application in shale gas exploitation[J].Journal of Energy Resources Technology,2013,136(2):1-6.
[7]孙可明,张树翠,辛利伟.页岩气储层层理方向对水力压裂裂纹扩展的影响[J].天然气工业,2016,36(2):48-53.Sun Keming,Zhang Shucui&Xin Liwei.Impacts of bedding directions of shale gas reservoirs on hydraulically induced crack propagation[J].Natural Gas Industry,2016,36(2):48-53.
[8]李勇明,陈曦宇,赵金洲,申峰,乔红军.水平井分段多簇压裂缝间干扰研究[J].西南石油大学学报(自然科学版),2016,38(1):76-83.Li Yongming,Chen Xiyu,Zhao Jinzhou,Shen Feng&Qiao Hongjun.The effects of crack interaction in multi-stage horizontal fracturing[J].Journal of Southwest Petroleum University(Science&Technology Edition),2016,38(1):76-83.
[9]张然,李根生,朱海燕.水平多裂缝交错扩展及其诱导应力干扰研究[J].西南石油大学学报(自然科学版),2017,39(1):91-99.Zhang Ran,Li Gensheng&Zhu Haiyan.Dynamic propagation of multiple horizontal fractures and mutual interference between induced stresses[J].Journal of Southwest Petroleum University(Science&Technology Edition),2017,39(1):91-99.
[10]赵金洲,许文俊,李勇明,蔡坤赤,徐苗.低渗透油气藏水平井分段多簇压裂簇间距优化新方法[J].天然气工业,2016,36(10):63-69.Zhao Jinzhou,Xu Wenjun,Li Yongming,Cai Kunchi&Xu Miao.A new method for cluster spacing optimization of multi-cluster staged fracturing in horizontal wells of low-permeability oil and gas reservoirs[J].Natural Gas Industry,2016,36(10):63-69.
[11]尉雪梅,吴飞鹏,刘恒超,徐尔斯,张艳玉,蒲春生.燃爆压裂井井周诱导应力分布规律[J].中国石油大学学报(自然科学版),2018,42(1):105-112.Wei Xuemei,Wu Feipeng,Liu Hengchao,Xu Ersi,Zhang Yanyu&Pu Chunsheng.Distribution of induced stress by high energy gas fracturing in wellbore[J].Journal of China University of Petroleum(Edition of Natural Science),2018,42(1):105-112.
[12]Sneddon LN&Elliott HA.The opening of a Griffith crack under internal pressure[J].Quarterly of Applied Mathematics,1946,4(3):262-267.
[13]Sneddon IN.The distribution of stress in the neighbourhood of a crack in an elastic solid[J].Proceedings of the Royal Society of London,Series A,Mathematical and Physical Sciences,1946,187(1009):229-260.
[14]Warpinski NR&Branagan PT.Altered-stress fracturing[J].Journal of Petroleum Technology,1989,41(9):990-997.
[15]Siebrits E,Elbel JL,Hoover RS,Diyashev IR,Griffin LG,Demetrius SL,et al.Refracture reorientation enhances gas production in Barnett shale tight gas wells[C]//Paper 63030-MS presented at the SPE Annual Technical Conference and Exhibition,1-4 October 2000,Dallas,Texas,USA.
[16]刘雨,艾池.多级压裂诱导应力作用下天然裂缝开启规律研究[J].石油钻探技术,2015,43(1):20-26.Liu Yu&Ai Chi.Opening of natural fractures under induced stress in multi-stage fracturing[J].Petroleum Drilling Techniques,2015,43(1):20-26.
[17]Griffith AA.The Phenomena of rupture and flow in solids[J].Philosophical Transactions of the Royal Society of London,Series A,1921,221(2):163-198.
[18]Irwin G.Analysis of stresses and strains near the end of a crack traversing a plate[J].Journal of Applied Mechanics,1957,24:361-364.
[19]Atkinson BK.岩石断裂力学[M].北京:地震出版社,1992.Atkinson BK.Rock fracture mechanics[M].Beijing:Earthquake Press,1992.
[20]尹祥础.建议采用的岩石断裂韧度测定方法[J].世界地震译丛,1989,20(6):74-85.Yin Xiangchu.Recommended method of determination of rock fracture toughness[J].Translated World Seismology,1989,20(6):74-85.
[2]叶显军,张惠生,田国理.液体火药高能气体压裂技术研究和在深层油气藏中的应用[J].石油勘探与开发,2000,27(3):67-69.Ye Xianjun,Zhang Huisheng&Tian Guoli.The high energy gas fracturing technique of liquid explosive and its application in deep-seated oil and gas reservoirs[J].Petroleum Exploration and Development,2000,27(3):67-69.
[3]陈莉静,李宁,王俊奇.高能复合射孔爆生气体作用下预存裂缝起裂扩展研究[J].石油勘探与开发,2005,32(6):91-93.Chen Lijing,Li Ning&Wang Junqi.Initiation and extension of existing cracks under detonation gas loading in a high energy combined perforation[J].Petroleum Exploration and Development,2005,32(6):91-93.
[4]雷群,胥云,蒋廷学,丁云宏,王晓泉,卢海兵.用于提高低-特低渗透油气藏改造效果的缝网压裂技术[J].石油学报,2009,30(2):237-241.Lei Qun,Xu Yun,Jiang Tingxue,Ding Yunhong,Wang Xiaoquan&Lu Haibing."Fracture network"fracturing technique for improving post-fracturing performance of low and ultra-low permeability reserviors[J].Acta Petrolei Sinica,2009,30(2):237-241.
[5]周健,陈勉,金衍,张广清.多裂缝储层水力裂缝扩展机理试验[J].中国石油大学学报(自然科学版),2008,32(4):51-54.Zhou Jian,Chen Mian,Jin Yan&Zhang Guangqing.Experiment of propagation mechanism of hydraulic fracture in multi-fracture reservoir[J].Journal of China University of Petroleum(Edition of Natural Science),2008,32(4):51-54.
[6]Li Jia,Guo Boyun&Yin Feng.An analytical solution of fractureinduced stress and its application in shale gas exploitation[J].Journal of Energy Resources Technology,2013,136(2):1-6.
[7]孙可明,张树翠,辛利伟.页岩气储层层理方向对水力压裂裂纹扩展的影响[J].天然气工业,2016,36(2):48-53.Sun Keming,Zhang Shucui&Xin Liwei.Impacts of bedding directions of shale gas reservoirs on hydraulically induced crack propagation[J].Natural Gas Industry,2016,36(2):48-53.
[8]李勇明,陈曦宇,赵金洲,申峰,乔红军.水平井分段多簇压裂缝间干扰研究[J].西南石油大学学报(自然科学版),2016,38(1):76-83.Li Yongming,Chen Xiyu,Zhao Jinzhou,Shen Feng&Qiao Hongjun.The effects of crack interaction in multi-stage horizontal fracturing[J].Journal of Southwest Petroleum University(Science&Technology Edition),2016,38(1):76-83.
[9]张然,李根生,朱海燕.水平多裂缝交错扩展及其诱导应力干扰研究[J].西南石油大学学报(自然科学版),2017,39(1):91-99.Zhang Ran,Li Gensheng&Zhu Haiyan.Dynamic propagation of multiple horizontal fractures and mutual interference between induced stresses[J].Journal of Southwest Petroleum University(Science&Technology Edition),2017,39(1):91-99.
[10]赵金洲,许文俊,李勇明,蔡坤赤,徐苗.低渗透油气藏水平井分段多簇压裂簇间距优化新方法[J].天然气工业,2016,36(10):63-69.Zhao Jinzhou,Xu Wenjun,Li Yongming,Cai Kunchi&Xu Miao.A new method for cluster spacing optimization of multi-cluster staged fracturing in horizontal wells of low-permeability oil and gas reservoirs[J].Natural Gas Industry,2016,36(10):63-69.
[11]尉雪梅,吴飞鹏,刘恒超,徐尔斯,张艳玉,蒲春生.燃爆压裂井井周诱导应力分布规律[J].中国石油大学学报(自然科学版),2018,42(1):105-112.Wei Xuemei,Wu Feipeng,Liu Hengchao,Xu Ersi,Zhang Yanyu&Pu Chunsheng.Distribution of induced stress by high energy gas fracturing in wellbore[J].Journal of China University of Petroleum(Edition of Natural Science),2018,42(1):105-112.
[12]Sneddon LN&Elliott HA.The opening of a Griffith crack under internal pressure[J].Quarterly of Applied Mathematics,1946,4(3):262-267.
[13]Sneddon IN.The distribution of stress in the neighbourhood of a crack in an elastic solid[J].Proceedings of the Royal Society of London,Series A,Mathematical and Physical Sciences,1946,187(1009):229-260.
[14]Warpinski NR&Branagan PT.Altered-stress fracturing[J].Journal of Petroleum Technology,1989,41(9):990-997.
[15]Siebrits E,Elbel JL,Hoover RS,Diyashev IR,Griffin LG,Demetrius SL,et al.Refracture reorientation enhances gas production in Barnett shale tight gas wells[C]//Paper 63030-MS presented at the SPE Annual Technical Conference and Exhibition,1-4 October 2000,Dallas,Texas,USA.
[16]刘雨,艾池.多级压裂诱导应力作用下天然裂缝开启规律研究[J].石油钻探技术,2015,43(1):20-26.Liu Yu&Ai Chi.Opening of natural fractures under induced stress in multi-stage fracturing[J].Petroleum Drilling Techniques,2015,43(1):20-26.
[17]Griffith AA.The Phenomena of rupture and flow in solids[J].Philosophical Transactions of the Royal Society of London,Series A,1921,221(2):163-198.
[18]Irwin G.Analysis of stresses and strains near the end of a crack traversing a plate[J].Journal of Applied Mechanics,1957,24:361-364.
[19]Atkinson BK.岩石断裂力学[M].北京:地震出版社,1992.Atkinson BK.Rock fracture mechanics[M].Beijing:Earthquake Press,1992.
[20]尹祥础.建议采用的岩石断裂韧度测定方法[J].世界地震译丛,1989,20(6):74-85.Yin Xiangchu.Recommended method of determination of rock fracture toughness[J].Translated World Seismology,1989,20(6):74-85.