饱和砂岩在疲劳载荷作用下的黏弹性性质
摘要
采用由法国引进的Metravib热机械分析仪,用正弦波加载方式,模拟地震波(行波)的传播,试验时固定静载为100 N,正弦波动载荷恒为60 N,将总载荷控制在屈服点以下;在温度为-50℃～125℃、升温速率保持在1℃/min、频率为5～90 Hz的条件下,对饱和泵油长石砂岩、彭山砂岩圆柱形样品进行单轴循环加载试验,求取饱和泵油长石砂岩和彭山砂岩波的能量衰减、虚模量、杨氏模量、弹性波速度与温度和频率的关系。以此研究饱和多孔岩石中行波的能量衰减和虚模量随温度的变化规律,取得行波随频率增高饱和多孔岩石的能量衰减峰和虚模量峰的峰位向高温方向移动、能量衰减峰和虚模量峰的强度增大的热激活弛豫规律,这种行波规律也是热激活弛豫机制引起。同时,获得饱和岩石的杨氏模量和弹性波速度对温度和频率的动态响应。杨氏模量和弹性波波速随温度升高而下降,随频率增高而增大,具有较明显的频散效应,随温度升高频散效应有减弱的趋势,取得与低频共振的驻波试验同样的热激活弛豫规律,说明热激活弛豫规律在饱和多孔岩石中具有一定的普适性。其结果是研究时温等效的试验和理论基础;同时该研究结果对岩石物理理论模型研究具有很好的指导意义,对现场地震波和声波测试结果和地震勘探资料的解释具有现实意义。
Experiments are performed by Metravib dynamic mechanical analyzer under sine wave loading as to imitate the seismic wave(travelling wave).The static load is fixed to 100 N,and the constant dynamic load of the sine wave is 60 N,so that the total loading force is controlled under yield stress.Temperature is controlled between-50 ℃-125 ℃,and the heating speed is 1 ℃/min.At frequency of 5-90 Hz,pump-oil saturated arkoses and Pengshan sandstones are tested under uniaxial cyclic loading.The variations of travelling wave energy attenuation,imaginary modulus,Young's modulus and elastic wave velocity with temperature or frequency are obtained.The energy attenuation peak and the imaginary modulus peak shift to higher temperatures when the frequency increases;and the energy attenuation and imaginary peak values increase for the travelling wave.These phenomena are caused by thermal relaxation mechanism.The Young's modulus and elastic wave velocity increase with frequency increase and decrease with temperature increase.These are obvious frequency dispersion,and the dispersion weakens when temperature decreases.The experimental results are similar to the low-frequency resonance standing wave experimental results.Thus the thermal relaxation regularities generally exist in saturated porous rocks.The results are the experimental and theoretical foundation for the study of time-temperature equivalence,and are very instructive for the study of theoretical rock physics model.This investigation is very helpful to the interpretation of seismic,acoustic wave,and seismic prospecting data.
Experiments are performed by Metravib dynamic mechanical analyzer under sine wave loading as to imitate the seismic wave(travelling wave).The static load is fixed to 100 N,and the constant dynamic load of the sine wave is 60 N,so that the total loading force is controlled under yield stress.Temperature is controlled between-50 ℃-125 ℃,and the heating speed is 1 ℃/min.At frequency of 5-90 Hz,pump-oil saturated arkoses and Pengshan sandstones are tested under uniaxial cyclic loading.The variations of travelling wave energy attenuation,imaginary modulus,Young's modulus and elastic wave velocity with temperature or frequency are obtained.The energy attenuation peak and the imaginary modulus peak shift to higher temperatures when the frequency increases;and the energy attenuation and imaginary peak values increase for the travelling wave.These phenomena are caused by thermal relaxation mechanism.The Young's modulus and elastic wave velocity increase with frequency increase and decrease with temperature increase.These are obvious frequency dispersion,and the dispersion weakens when temperature decreases.The experimental results are similar to the low-frequency resonance standing wave experimental results.Thus the thermal relaxation regularities generally exist in saturated porous rocks.The results are the experimental and theoretical foundation for the study of time-temperature equivalence,and are very instructive for the study of theoretical rock physics model.This investigation is very helpful to the interpretation of seismic,acoustic wave,and seismic prospecting data.
引文
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[2]席道瑛,陈运平,陶月赞,等.岩石的非线性弹性滞后特征[J].岩石力学与工程学报,2006,25(6):1 086–1 093.(XI Daoying,CHEN Yunping,TAO Yuezan,et al.Nonlinear elastic hysteric characteristics of rocks[J].Chinese Journal of Rock Mechanics and Engineering,2006,25(6):1 086–1 093.(in Chinese))
[3]BATZLE M L,HAN D H,HOFMANN R.Fluid mobility and frequency-dependent seismic velocity direct measurements[J].Geophysics,2006,71(1):1–9.
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[7]SPENCER J W.Stress relaxations at low frequencies in fluid saturated rocks:attenuation and modulus dispersion[J].Journal of Geophysical Research,1981,86(B3):1 803–1 812.
[8]BATZLE M,WANG Z J.Seismic properties of pore fluids[J].Geophysics,1992,57(11):1 396–1 408.
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[12]席道瑛,张程远,刘小燕.储层砂岩的各向异性[J].石油地球物理勘探,2001,36(2):187–192.(XI Daoying,ZHANG Chengyuan,LIU Xiaoyan.Anisotropy in reservoir sandstone[J].Oil Geophysical Prospecting,2001,36(2):187–192.(in Chinese))
[13]席道瑛,谢端,易良坤,等.温度对岩石模量和波速的影响[J].岩石力学与工程学报,1998,17(增):802–807.(XI Daoying,XIE Duan,YI Liangkun,et al.Effects of temperature on rock′s modulus and wave velocity[J].Chinese Journal of Rock Mechanics and Engineering,1998,17(Supp.):802–807.(in Chinese))
[14]杜赟,席道瑛,徐松林,等.多孔岩石波传播的热弛豫模型修正[J].地球物理学报,2009,52(12):3 051–3 060.(DU Yun,XI Daoying,XU Songlin,et al.The modification of thermal relaxation mechanism for wave propagation in porous rocks[J].Chinese Journal of Geophysics,2009,52(12):3 051–3 060.(in Chinese))
[15]XI D Y,XU S L,DU Y,et al.Wave propagation analysis of porous rocks with thermal activated relaxation mechanism[J].Journal of Applied Geophysics,2011,73(3):289–303.
[16]席道瑛,程经毅,席军.饱和砂岩滞弹性弛豫热激活过程机制探讨[J].石油地球物理勘探,1998,33(3):348–354.(XI Daoying,CHENG Jingyi,XI Jun.Research on the heating activation mechanism of viscoelastic relaxation in fluid-saturated sandstone[J].Oil Geophysical Prospecting,1998,33(3):348–354.(in Chinese))
[17]易良坤,席道瑛,刘小燕.孔隙介质热激活弛豫波动理论[J].岩石力学与工程学报,2003,22(5):803–809.(YI Liangkun,XI Daoying,LIU Xiaoyan.Wave theory with heat effects in porous media[J].Chinese Journal of Rock Mechanics and Engineering,2003,22(5):803–809.(in Chinese))
[2]席道瑛,陈运平,陶月赞,等.岩石的非线性弹性滞后特征[J].岩石力学与工程学报,2006,25(6):1 086–1 093.(XI Daoying,CHEN Yunping,TAO Yuezan,et al.Nonlinear elastic hysteric characteristics of rocks[J].Chinese Journal of Rock Mechanics and Engineering,2006,25(6):1 086–1 093.(in Chinese))
[3]BATZLE M L,HAN D H,HOFMANN R.Fluid mobility and frequency-dependent seismic velocity direct measurements[J].Geophysics,2006,71(1):1–9.
[4]WHITE J E.Computed seismic speeds and attenuation in rocks with partial gas saturation[J].Geophysics,1975,40(2):224–232.
[5]GIST G A.Interpreting laboratory velocity measurements in partially gas-saturated rocks[J].Geophysics,1994,59(7):1 100–1 109.
[6]PRIDE S R,HARRIS J M,JOHNSON D L,et al.Permeability dependence of seismic amplitudes[J].The Leading Edge,2003,22(6):518–525.
[7]SPENCER J W.Stress relaxations at low frequencies in fluid saturated rocks:attenuation and modulus dispersion[J].Journal of Geophysical Research,1981,86(B3):1 803–1 812.
[8]BATZLE M,WANG Z J.Seismic properties of pore fluids[J].Geophysics,1992,57(11):1 396–1 408.
[9]BATZLE M,HOFMANN R,HAN D H,et al.Fluids and frequency dependent seismic velocity of rocks[J].The Leading Edge,2001,20(2):168–171.
[10]XI D Y,LIU B,LIU W,et al.The dependence of relaxation attenuation of saturation rock on time and temperature[J].Chinese Journal of Geophysics,2000,43(6):873–880.
[11]XI D Y,LIU B,TIAN X Y.Anisotropy and nonlinear viscoelastic behavior of saturated rocks[J].Chinese Journal of Geophysics,2002,45(1):101–111.
[12]席道瑛,张程远,刘小燕.储层砂岩的各向异性[J].石油地球物理勘探,2001,36(2):187–192.(XI Daoying,ZHANG Chengyuan,LIU Xiaoyan.Anisotropy in reservoir sandstone[J].Oil Geophysical Prospecting,2001,36(2):187–192.(in Chinese))
[13]席道瑛,谢端,易良坤,等.温度对岩石模量和波速的影响[J].岩石力学与工程学报,1998,17(增):802–807.(XI Daoying,XIE Duan,YI Liangkun,et al.Effects of temperature on rock′s modulus and wave velocity[J].Chinese Journal of Rock Mechanics and Engineering,1998,17(Supp.):802–807.(in Chinese))
[14]杜赟,席道瑛,徐松林,等.多孔岩石波传播的热弛豫模型修正[J].地球物理学报,2009,52(12):3 051–3 060.(DU Yun,XI Daoying,XU Songlin,et al.The modification of thermal relaxation mechanism for wave propagation in porous rocks[J].Chinese Journal of Geophysics,2009,52(12):3 051–3 060.(in Chinese))
[15]XI D Y,XU S L,DU Y,et al.Wave propagation analysis of porous rocks with thermal activated relaxation mechanism[J].Journal of Applied Geophysics,2011,73(3):289–303.
[16]席道瑛,程经毅,席军.饱和砂岩滞弹性弛豫热激活过程机制探讨[J].石油地球物理勘探,1998,33(3):348–354.(XI Daoying,CHENG Jingyi,XI Jun.Research on the heating activation mechanism of viscoelastic relaxation in fluid-saturated sandstone[J].Oil Geophysical Prospecting,1998,33(3):348–354.(in Chinese))
[17]易良坤,席道瑛,刘小燕.孔隙介质热激活弛豫波动理论[J].岩石力学与工程学报,2003,22(5):803–809.(YI Liangkun,XI Daoying,LIU Xiaoyan.Wave theory with heat effects in porous media[J].Chinese Journal of Rock Mechanics and Engineering,2003,22(5):803–809.(in Chinese))
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