天然裂缝对水力裂缝延伸的影响研究
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摘要
基于水力裂缝与天然裂缝的等效平面力学理论,综合考虑裂缝剪切与张性破坏机制,建立水力裂缝延伸数值模型,对天然裂缝作用下的水力裂缝延伸方向、延伸形态进行综合分析。结果表明:当天然裂缝位于井周附近时,在水平最大应力方向上,天然裂缝在靠近井眼位置时,容易对水力裂缝产生转向作用,在水平最小应力方向上,天然裂缝远离水力裂缝延伸方向,对水力裂缝延伸的影响也逐渐减小;当天然裂缝与水力裂缝相遇时,在低逼近角条件下,水力裂缝易转向,并沿天然裂缝延伸,在高逼近角条件下,则易直接穿过天然裂缝;低裂缝强度和低水平应力比值条件下,天然裂缝对水力裂缝延伸影响更明显。通过大尺寸真三轴水力压裂实验对数值模型进行验证,数值计算结果与实验数据吻合良好,证明该模型的适用性。该研究成果可为天然裂缝发育储层水力压裂提供一定理论指导。
Based on the equivalent plane mechanic theory of hydraulic and natural fractures,a numerical model of hydraulic fracture propagation is established by comprehensively considering fracture shear and tensile failure mechanisms. A comprehensive analysis is provided for the effects of natural fracture on the hydraulic fracture propagation direction and morphology. Research indicates that the natural fracture near the well usually causes hydraulic steering along the maximum horizontal stress. However,the natural fracture near the well is far away from the hydraulic fracture propagation direction and the corresponding influence is gradually decreasing. When natural fracture is intersected with hydraulic fracture,hydraulic fracture tends to steer and propagate along natural fracture direction under low approach angel and hydraulic fracture is prone to cross natural fracture under high approach angle. The influence of natural fracture on hydraulic fracture propagation increases under low fracture strength and low horizontal stress ratio. This numerical model is verified by actual large-scale triaxial hydraulic fracturing experiment. The numerical simulation is in good agreement with laboratory experiment data,which shows favorable model applicability. This research could provide certain theoretical guidance for the hydraulic fracturing in natural fractured reservoirs.
Based on the equivalent plane mechanic theory of hydraulic and natural fractures,a numerical model of hydraulic fracture propagation is established by comprehensively considering fracture shear and tensile failure mechanisms. A comprehensive analysis is provided for the effects of natural fracture on the hydraulic fracture propagation direction and morphology. Research indicates that the natural fracture near the well usually causes hydraulic steering along the maximum horizontal stress. However,the natural fracture near the well is far away from the hydraulic fracture propagation direction and the corresponding influence is gradually decreasing. When natural fracture is intersected with hydraulic fracture,hydraulic fracture tends to steer and propagate along natural fracture direction under low approach angel and hydraulic fracture is prone to cross natural fracture under high approach angle. The influence of natural fracture on hydraulic fracture propagation increases under low fracture strength and low horizontal stress ratio. This numerical model is verified by actual large-scale triaxial hydraulic fracturing experiment. The numerical simulation is in good agreement with laboratory experiment data,which shows favorable model applicability. This research could provide certain theoretical guidance for the hydraulic fracturing in natural fractured reservoirs.
引文
[1]张士诚,郭天魁,周彤,等.天然页岩压裂裂缝扩展机理试验[J].石油学报,2014,35(3):496-503.
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[6]陈勉,周健,金衍,等.随机裂缝性储层压裂特征实验研究[J].石油学报,2008,29(3):431-434.
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[15]曾青冬,姚军.基于扩展有限元的页岩水力压裂数值模拟[J].应用数学和力学,2014,35(11):1239-1248.
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[18]朱万成,唐春安,杨天鸿,等.岩石破裂过程分析(RFPA2D)系统的细观单元本构关系及验证[J].岩石力学与工程学报,2003,22(1):24-29.
[19]梁利喜,黄静,刘向君,等.天然裂缝对页岩储层网状诱导缝的控制作用[J].成都理工大学学报(自然科学版),2016,43(6):696-702.
[20]于庆磊.基于数字图像的岩石类材料破裂过程分析方法研究[D].沈阳:东北大学,2008.
[21]朱圣举,赵向原,张皎生,等.低渗透砂岩油藏天然裂缝开启压力及影响因素[J].西北大学学报(自然科学版),2016,46(4):573-578.
[22]刘雨.多级压裂诱导应力对天然裂缝开启影响研究[D].大庆:东北石油大学,2014.
[23]张莉,杨亚娟,岳乐平,等.哈南阿尔善油藏微裂缝特征及其对开发的影响[J].石油与天然气地质,2001,22(2):158-160.
[24]DAHI-TALEGHANI A,OLSON J E.Numerical modeling of multi-stranded hydraulic fracture propagation:Accounting for the interaction between induced and natural fractures[J].SPE Journal,2011,16(3):575-581.
[25]RAHMAN M M,RAHMAN S S.Studies of hydraulic fracture-propagation behavior in presence of natural fractures:fully coupled fractured-reservoir modeling in poroelastic environments[J].International Journal of Geomechanics,2013,13(6):809-826.
[26]侯振坤,杨春和,王磊,等.大尺寸真三轴页岩水平井水力压裂物理模拟试验与裂缝延伸规律分析[J].岩土力学,2016,37(2):407-414.
[27]程万,金衍,陈勉,等.三维空间中水力裂缝穿透天然裂缝的判别准则[J].石油勘探与开发,2014,41(3):336-340.
[2]唐颖,唐玄,王广源,等.页岩气开发水力压裂技术综述[J].地质通报,2011,30(2):393-399.
[3]GALE J F W,REED R M,HOLDER J.Natural fractures in the Barnett Shale and their importance for hydraulic fracture treatments[J].AAPG Bulletin,2007,91(4):603-622.
[4]曾青冬,姚军,孙致学.页岩气藏压裂缝网扩展数值模拟[J].力学学报,2015,47(6):994-999.
[5]马耕,张帆,刘晓,等.天然裂缝对煤岩体水力裂缝扩展影响研究[J].河南理工大学学报(自然科学版),2016,35(2):178-182.
[6]陈勉,周健,金衍,等.随机裂缝性储层压裂特征实验研究[J].石油学报,2008,29(3):431-434.
[7]NORMA L,JESSEN F W.The effects of existing fractures in rocks on the extension of hydraulic fractures[J].Journal of Petroleum Technology,1963,15(2):203-209.
[8]LIN C,HE J,LI X,et al.An experimental investigation into the effects of the anisotropy of shale on hydraulic fracture propagation[J].Rock Mechanics&Rock Engineering,2016,50(3):1-12.
[9]ZHOU J,JIN Y,CHEN M.Experimental investigation of hydraulic fracturing in random naturally fractured blocks[J].International Journal of Rock Mechanics&Mining Sciences,2010,47(7):1193-1199.
[10]HOSSAIN M M,RAHMAN M K.Numerical simulation of complex fracture growth during tight reservoir stimulation by hydraulic fracturing[J].Journal of Petroleum Science&Engineering,2008,60(2):86-104.
[11]罗天雨,王嘉淮,赵金洲,等.天然裂缝对水力压裂的影响研究[J].石油天然气学报,2007,29(5):65-66.
[12]宋晨鹏,卢义玉,夏彬伟,等.天然裂缝对煤层水力压裂裂缝扩展的影响[J].东北大学学报(自然科学版),2014,35(5):756-760.
[13]周健,陈勉,金衍,等.压裂中天然裂缝剪切破坏机制研究[J].岩石力学与工程学报,2008,27(增刊):2637-2641.
[14]陈勉,金衍,张广清.石油工程岩石力学[M].北京:科学出版社,2008:168-169.
[15]曾青冬,姚军.基于扩展有限元的页岩水力压裂数值模拟[J].应用数学和力学,2014,35(11):1239-1248.
[16]姜浒,刘书杰,何保生,等.页岩气储层水力压裂机理研究[J].科学技术与工程,2014,14(12):23-25.
[17]GUO T,ZHANG S,QU Z,et al.Experimental study of hydraulic fracturing for shale by stimulated reservoir volume[J].Fuel,2014,128(14):373-380.
[18]朱万成,唐春安,杨天鸿,等.岩石破裂过程分析(RFPA2D)系统的细观单元本构关系及验证[J].岩石力学与工程学报,2003,22(1):24-29.
[19]梁利喜,黄静,刘向君,等.天然裂缝对页岩储层网状诱导缝的控制作用[J].成都理工大学学报(自然科学版),2016,43(6):696-702.
[20]于庆磊.基于数字图像的岩石类材料破裂过程分析方法研究[D].沈阳:东北大学,2008.
[21]朱圣举,赵向原,张皎生,等.低渗透砂岩油藏天然裂缝开启压力及影响因素[J].西北大学学报(自然科学版),2016,46(4):573-578.
[22]刘雨.多级压裂诱导应力对天然裂缝开启影响研究[D].大庆:东北石油大学,2014.
[23]张莉,杨亚娟,岳乐平,等.哈南阿尔善油藏微裂缝特征及其对开发的影响[J].石油与天然气地质,2001,22(2):158-160.
[24]DAHI-TALEGHANI A,OLSON J E.Numerical modeling of multi-stranded hydraulic fracture propagation:Accounting for the interaction between induced and natural fractures[J].SPE Journal,2011,16(3):575-581.
[25]RAHMAN M M,RAHMAN S S.Studies of hydraulic fracture-propagation behavior in presence of natural fractures:fully coupled fractured-reservoir modeling in poroelastic environments[J].International Journal of Geomechanics,2013,13(6):809-826.
[26]侯振坤,杨春和,王磊,等.大尺寸真三轴页岩水平井水力压裂物理模拟试验与裂缝延伸规律分析[J].岩土力学,2016,37(2):407-414.
[27]程万,金衍,陈勉,等.三维空间中水力裂缝穿透天然裂缝的判别准则[J].石油勘探与开发,2014,41(3):336-340.