水力压裂裂缝扩展声发射破裂机制判定方法研究
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摘要
水力压裂室内模拟实验系统可以模拟各种地层条件下的压裂实验,实验中利用声发射设备对裂缝的起裂和延伸的过程进行实时动态监测,实验后对形成裂缝的形态进行直接观察,从而为压裂理论的研究和论证提供一种重要的手段。本文利用声发射技术对砂岩、煤岩、页岩三类岩石水力压裂模拟实验进行了监测,对声发射数据进行了分析,并把日本混凝土材料协会(JCMS-III B5706 2003)定义的两个参数(频度和RA值)成功地应用于水力压裂模拟实验。研究表明:用声发射信号的频度和RA值两个参数联合评价压裂模拟实验的破裂机制是可行的,可以区分张性破裂和剪切破裂;致密砂岩主要形成张性裂缝。煤岩和页岩既有张性裂缝,又有剪切裂缝,这与煤岩和页岩存在天然裂缝,压裂时水力裂缝与天然裂缝相互干扰作用有关。上述结果可用于指导水力压裂现场微地震监测。
Hydraulic fracturing laboratory simulation experiment can simulate fracturing experiment under various stratigraphic formation conditions.In experiment,real-time dynamic monitoring of crack initiation and extension process was carried out by acoustic emission equipment.After experiment,the morphology of cracks may be observed directly.Thus,it provides an important means for study and demonstration of fracturing theory.In this paper,acoustic emission technique is used to monitor hydraulic fracturing simulation experiment of three lithologic rocks including sandstone,coal and shale rock,and acoustic emission data are analyzed.Two parameters defined by Japanese concrete material association(JCMS-III B5706 2003)are successfully applied to the hydraulic fracturing simulation experiment.Study results show that it is feasible to evaluate the fracture mechanism in fracturing simulation experiment by combining two parameters of acoustic emission:frequency of acoustic emission signals and RA value,which can distinguish tensile rupture from shear rupture.Tight sandstone produces tensile rupture.For coal and shale rocks with relatively more developed natural fractures,there are not only tensile rupture,but also a certain number of shear rupture.Shear rupture is easy to occur due to the existence of natural cracks,or due to the interference of hydraulic fractures and natural fractures.Above results may be used to guide microseismic monitoring in hydraulic fracturing site.
Hydraulic fracturing laboratory simulation experiment can simulate fracturing experiment under various stratigraphic formation conditions.In experiment,real-time dynamic monitoring of crack initiation and extension process was carried out by acoustic emission equipment.After experiment,the morphology of cracks may be observed directly.Thus,it provides an important means for study and demonstration of fracturing theory.In this paper,acoustic emission technique is used to monitor hydraulic fracturing simulation experiment of three lithologic rocks including sandstone,coal and shale rock,and acoustic emission data are analyzed.Two parameters defined by Japanese concrete material association(JCMS-III B5706 2003)are successfully applied to the hydraulic fracturing simulation experiment.Study results show that it is feasible to evaluate the fracture mechanism in fracturing simulation experiment by combining two parameters of acoustic emission:frequency of acoustic emission signals and RA value,which can distinguish tensile rupture from shear rupture.Tight sandstone produces tensile rupture.For coal and shale rocks with relatively more developed natural fractures,there are not only tensile rupture,but also a certain number of shear rupture.Shear rupture is easy to occur due to the existence of natural cracks,or due to the interference of hydraulic fractures and natural fractures.Above results may be used to guide microseismic monitoring in hydraulic fracturing site.
引文
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[4]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1):2637-2641(ZHOU Jian,CHEN Mian,JIN Yan,et al.Mechanism study of shearing slippage damage of natural fracture in hydraulic fracturing[J].Chinese Journal of Rock Mechanics and Engineering,2008,27(s1):2637-2641(in Chinese))
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[6]Malhotra V M,Carino N J.Handbook on Nondestructive Testing of Concrete[M].Chemical Rubber Company Press,2003:184-190.
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[8]JCMS-III B5706.Monitoring method for active cracks in concrete by acoustic emission[C].Japan:Federation of Construction Materials Industries,2003.
[9]Aldahdooh M A A,Bunnori N.Crack classification in reinforced concrete beams with varying thicknesses by mean of acoustic emission signal features[J].Construction and Building Materials,2013,45:282-288.
[10]Tomoda Y,Mori K,Kawasaki Y,et al.Monitoring corrosion-induced cracks in concrete by acoustic emission[C].Proceedings of FraMCoS-7,2010.
[11]Ohno K,Ohtsu M.Crack classification in concrete based on acoustic emission[J].Constr Build Mater,2010,24(12):2339-2346.
[12]Ohno K,Sawada K,Utsunomiya K,et al.Classification of micro-cracks generated in concrete by acoustic emission[J].Progress in Acoustic Emission,2008(19):347-354.
[13]Takaya S,Yamamoto T,Miyagawa T.AE properties of spalling crack induced by reinforcement corrosion[J].Progress in International Acoustic Emission Symposia,2008(19):303.
[14]Schumacher T.AE techniques applied to conventionally reinforced concrete bridge girders[R].Oregon DOTReport SPR633,2008:199.
[15]Hampton J,Frash L,Gutierrez M.Investigation of laboratory hydraulic fracture source mechanisms using acoustic emission[C].47th US Rock Mechanics Geomechanics Symposium,2013.
[16]LIANG Tiancheng,FU Haifeng,LU Yongjun.Source mechanism studies of acoustic emission in large-scale hydraulic fracturing experiment[C].Beijing:SPE Asia Pacific Hydraulic Fracturing Conference,2016.
[2]Warpinski N R,Teufel L W.Influence of geologic discontinuities on hydraulic fracture propagation[J].Journal of Petroleum Technology,1987,44(2):209-220.
[3]邓广哲,王世斌,黄炳香.煤岩水压裂缝扩展行为特性研究[J].岩石力学与工程学报,2004,23(20):3489-3493(DENG Guangzhe,WANG Shibing,HUANG Bingxiang.Research on behavior character of crack development induced by hydraulic fracturing in coal-rockmass[J].Chinese Journal of Rock Mechanics and Engineering,2004,23(20):3489-3493(in Chinese))
[4]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1):2637-2641(ZHOU Jian,CHEN Mian,JIN Yan,et al.Mechanism study of shearing slippage damage of natural fracture in hydraulic fracturing[J].Chinese Journal of Rock Mechanics and Engineering,2008,27(s1):2637-2641(in Chinese))
[5]Kanji O N O.Application of acoustic emission for structure diagnosis[J].Diagnostics and Structural Health Monitoring,2011,2(58):3-18.
[6]Malhotra V M,Carino N J.Handbook on Nondestructive Testing of Concrete[M].Chemical Rubber Company Press,2003:184-190.
[7]Ohtsu M,Yuyama S.Acoustic emission[M].Engelska,2001:26-32.
[8]JCMS-III B5706.Monitoring method for active cracks in concrete by acoustic emission[C].Japan:Federation of Construction Materials Industries,2003.
[9]Aldahdooh M A A,Bunnori N.Crack classification in reinforced concrete beams with varying thicknesses by mean of acoustic emission signal features[J].Construction and Building Materials,2013,45:282-288.
[10]Tomoda Y,Mori K,Kawasaki Y,et al.Monitoring corrosion-induced cracks in concrete by acoustic emission[C].Proceedings of FraMCoS-7,2010.
[11]Ohno K,Ohtsu M.Crack classification in concrete based on acoustic emission[J].Constr Build Mater,2010,24(12):2339-2346.
[12]Ohno K,Sawada K,Utsunomiya K,et al.Classification of micro-cracks generated in concrete by acoustic emission[J].Progress in Acoustic Emission,2008(19):347-354.
[13]Takaya S,Yamamoto T,Miyagawa T.AE properties of spalling crack induced by reinforcement corrosion[J].Progress in International Acoustic Emission Symposia,2008(19):303.
[14]Schumacher T.AE techniques applied to conventionally reinforced concrete bridge girders[R].Oregon DOTReport SPR633,2008:199.
[15]Hampton J,Frash L,Gutierrez M.Investigation of laboratory hydraulic fracture source mechanisms using acoustic emission[C].47th US Rock Mechanics Geomechanics Symposium,2013.
[16]LIANG Tiancheng,FU Haifeng,LU Yongjun.Source mechanism studies of acoustic emission in large-scale hydraulic fracturing experiment[C].Beijing:SPE Asia Pacific Hydraulic Fracturing Conference,2016.