饱和储层砂岩中流体粘度引起的超声波速度频散实验研究(英文)
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摘要
在实验室对5块储层砂岩进行了模拟地层压力条件下的超声波速度测试。砂岩样品采自WXS凹陷的W地层,覆盖了从低到高的孔隙度和渗透率范围。实验选用了卤水和4种不同密度油作为孔隙流体,结合温度变化,实现了对流体粘度引致的速度频散研究。对实验结果的分析表明:(1)对于高孔隙度和渗透率的样品,无论是哪种流体饱和,观察到的超声波速度测试值和零频率Gassmann预测值的差异较小(约2-3%),基本上可以用Biot模型解释;对于中等孔隙度和渗透率的样品,低粘度流体(<约3mP?S)的频散效应也可以用Biot模型得到合理解释;(2)对于低、中孔隙度和渗透率样品,当流体粘度增加时,喷射流机制起主导作用,导致严重的速度频散(可达8%)。对储层砂岩的微裂隙纵横比进行了估计并用于喷射流特征频率的计算,当高于该特征频率时,Gassmann理论的假设条件受到破坏,实验室测得的高频速度不能直接用于地震低频条件下的W地层砂岩的Gassmann流体替换研究。
Ultrasonic velocities of a set of saturated sandstone samples were measured at simulated in-situ pressures in the laboratory.The samples were obtained from the W formation of the WXS Depression and covered low to nearly high porosity and permeability ranges.The brine and four different density oils were used as pore fluids,which provided a good chance to investigate fluid viscosity-induced velocity dispersion.The analysis of experimental observations of velocity dispersion indicates that(1)the Biot model can explain most of the small discrepancy(about 2–3%)between ultrasonic measurements and zero frequency Gassmann predictions for high porosity and permeability samples saturated by all the fluids used in this experiment and is also valid for medium porosity and permeability samples saturated with low viscosity fluids(less than approximately 3 mP·S)and(2)the squirt flow mechanism dominates the low to medium porosity and permeability samples when fluid viscosity increases and produces large velocity dispersions as high as about 8%. The microfracture aspect ratios were also estimated for the reservoir sandstones and applied to calculate the characteristic frequency of the squirt flow model,above which the Gassmann’ s assumptions are violated and the measured high frequency velocities cannot be directly used for Gassmann’s fluid replacement at the exploration seismic frequency band for W formation sandstones.
Ultrasonic velocities of a set of saturated sandstone samples were measured at simulated in-situ pressures in the laboratory.The samples were obtained from the W formation of the WXS Depression and covered low to nearly high porosity and permeability ranges.The brine and four different density oils were used as pore fluids,which provided a good chance to investigate fluid viscosity-induced velocity dispersion.The analysis of experimental observations of velocity dispersion indicates that(1)the Biot model can explain most of the small discrepancy(about 2–3%)between ultrasonic measurements and zero frequency Gassmann predictions for high porosity and permeability samples saturated by all the fluids used in this experiment and is also valid for medium porosity and permeability samples saturated with low viscosity fluids(less than approximately 3 mP·S)and(2)the squirt flow mechanism dominates the low to medium porosity and permeability samples when fluid viscosity increases and produces large velocity dispersions as high as about 8%. The microfracture aspect ratios were also estimated for the reservoir sandstones and applied to calculate the characteristic frequency of the squirt flow model,above which the Gassmann’ s assumptions are violated and the measured high frequency velocities cannot be directly used for Gassmann’s fluid replacement at the exploration seismic frequency band for W formation sandstones.
引文
Ba,J.,Cao,H.,Yao,F.C.,Nie,J.X.,and Yang,H.Z.,2008,Double-porosity rock model and squirt flow in the laboratory frequency band:Applied Geophysics,5(4),261–276.
Batzle,M.,Hofmann,R.,Han,D.,and Castagna,J.,2001,Fluids and frequency dependent seismic velocity of rocks:The Leading Edge,20(2),168-171.
Batzle,M.L.,Han,D.,and Hofmann,R.,2006,Fluid mobility and frequency-dependent seismic velocity-Direct measurements:Geophysics,71(1),N1-N9.
Batzle,M.,and Wang,Z.,1992,Seismic properties of pore fluids:Geophysics,57(11),1396-1408.
Best,A.I.,and McCann,C.,1995,Seismic attenuation and pore-fluid viscosity in clay-rich reservoir sandstones:Geophysics,60(5),1386-1397.
Biot,M.A.,1956,Theory of propagation of elastic waves in afluid-saturated porous solid.I.Low-frequency range,II.Higher frequency range:Journal of the Acoustical Society of America,28(2),168-191.
Deng,J.X.,Shi,G.,and Yu,J.,2003,The research of the characteristics of ultrasonic velocity dispersion in fluid saturated rock:Acta Scicentiarum Naturalum UniversitisPekinesis(in Chinese),39(6),835-843.
Dvorkin,J.,Mavko,G.,and Nur,A.,1995,Squirt-flow in fully saturated rocks:Geophysics,60(1),97-107.
Dvorkin,J.,Nolen-Hoeksema,R.,and Nur,A.,1994,The squirt-flow mechanism:Macroscopic description:Geophysics,59(3),428-438.
Dvorkin,J.,and Nur,A.,1993,Dynamic poroelasticity:A unifi ed model with the squirt and the Biot mechanisms:Geophysics,58(4),524-533.
Gassmann,F.,1951,über die Elastizitt porser Medien:Veirteljahrsschrift der Naturforschenden Gesellschaft in Zürich,96,1-23.
Geertsma,J.,and Smit,D.C.,1961,Some aspects of elastic wave propagation in fluid-saturated porous solids:Geophysics,26(2),169-181.
Gurevich,B.,2002,Effect of fluid viscosity on elastic wave attenuation in porous rocks:Geophysics,67(1),264-270.
Han,D.,and Batzle,M.,2000a,Velocity,density and modulus of hydrocarbon fluids-empirical modeling:SEG Technical Program Expanded Abstracts,19(1),1867-1870.
Han,D.,and Batzle,M.,2000b,Velocity,density and modulus of hydrocarbonfluids-data measurement:SEG Technical Program Expanded Abstracts,19(1),1862-1866.
Hornby,B.E.,1998,Experimental laboratory determination of the dynamic elastic properties of wet,drained shales:Journal of Geophysical Research,103(B12),29945-29964.
Khazanehdari,J.,and Sothcott,J.,2003,Variation in dynamic elastic shear modulus of sandstone upon fluid saturation and substitution:Geophysics,68(2),472-481.
Li,J.C.,Shi,G.,and Chen,S.Y.,2005,Experimental study on effects of viscosity and salinity of liquid on rock velocity anisotropy:Acta Scicentiarum Naturalum Universitis Pekinesis(in Chinese),41(6),851-858.
Mavko,G.,and Nur,A.,1975,Melt squirt in the asthenosphere:Journal of Geophysical Research,80,1444-1448.
Mavko,G.,and Jizba,D.,1991,Estimating grain-scale fluid effects on velocity dispersion in rocks:Geophysics,56(12),1940-1949.
Mavko,G.,Mukerji,T.,and Dvorkin,J.,2009,The rock physics handbook:Tools for seismic analysis in porous media(2nd edition):Cambridge University Press,New York,p.312.
Murphy,W.F.,1984,Acoustic measures of partial gas saturation in tight sandstones:Journal of Geophysical Research,89,11549-11559.
Murphy,W.F.,Winkler,K.W.,and Kleinberg,R.L.,1984,Frame modulus reduction in sedimentary rock:Geophysical Research Letters,11(9),805-808.
Nie,J.X.,and Yang,D.H.,2008,Viscoelastic BISQ model for low-permeability sandstone with clay:Chinese Physics Letters,25(8),3079-3082.
Nie,J.X.,Yang,D.H.,and Ba,J.,2010,Velocity dispersion and attenuation of waves in low-porosity-permeability anisotropic viscoelastic media with clay:Chinese Journal of Geophysics(in Chinese),53(2),385-392.
Nie,J.X.,Yang,D.H.,and Yang,H.Z.,2008,A generalized viscoelastic Biot/squirt model for clay-bearing sandstones in a wide range of permeabilities:Applied Geophysics,5(4),249-260.
O’Connell,R.J.,and Budiansky,B.,1977,Viscoelastic properties of fluid-saturated cracked solids:Journal of Geophysical Research,82,5719-5740.
Parra,J.O.,2000,Poroelastic model to relate seismic wave attenuation and dispersion to permeability anisotropy:Geophysics,65(1),202-210.
Peselnick,L.,and Outerbridge,W.F.,1961,Internal friction in shear and shear modulus of Solenhofen limestone over a frequency range of107cycles per second:Journal of Geophysical Research,66(2),581-588.
Shi,G.,and Yang,D.Q.,2002,Determination of the elastic wave velocities in porous rocks with the change of overburden pressure and its universal significance:Science in China,Ser.D,45(7),635-642.
Spencer,J.W.,1981,Stress relaxations at low frequenciesin fluid saturated rocks:Attenuation and modulusdispersion:Journal of Geophysical Research,86(B3),1803-1812.
Wang,Z.,and Nur,A.,1990,Dispersion analysis of acoustic velocities in rocks:The Journal of the Acoustical Society of America,87(6),2384-2395.
Wang,Z.,and Nur,A.M.,1988,Velocity dispersion and the“local flow’’mechanism in rocks:SEG Technical Program Expanded Abstracts,7(1),548-550.
Wei,X.C.,Lu,M.H.,Ba,J.,and Yang,H.Z.,2008,Dispersion and attenuation of elastic waves in a viscous fluid-saturated anisotropic porous solid:Chinese Journal of Geophysics(in Chinese),51(1),213-220.
Winkler,K.W.,1985,Dispersion analysis of velocity and attenuation in Berea sandstone:Journal of Geophysical Research,90,6793-6800.
Winkler,K.W.,1986,Estimates of velocity dispersion between seismic and ultrasonic frequencies:Geophysics,51(1),183-189.
Yang,D.H.,and Zhang,Z.J.,2002,Poroelastic wave equation including the Biot/squirt mechanism and the solid/?uid coupling anisotropy:Wave Motion,35(3),223-245.
Zhang,Y.Z.,Chu,Z.H.,Li,M.,and Luo,M.,2001,An experimental study of acoustic dispersion of rock and extrapolation of the velocity:Chinese Journal of Geophysics(in Chinese),44(1),136-141.
Batzle,M.,Hofmann,R.,Han,D.,and Castagna,J.,2001,Fluids and frequency dependent seismic velocity of rocks:The Leading Edge,20(2),168-171.
Batzle,M.L.,Han,D.,and Hofmann,R.,2006,Fluid mobility and frequency-dependent seismic velocity-Direct measurements:Geophysics,71(1),N1-N9.
Batzle,M.,and Wang,Z.,1992,Seismic properties of pore fluids:Geophysics,57(11),1396-1408.
Best,A.I.,and McCann,C.,1995,Seismic attenuation and pore-fluid viscosity in clay-rich reservoir sandstones:Geophysics,60(5),1386-1397.
Biot,M.A.,1956,Theory of propagation of elastic waves in afluid-saturated porous solid.I.Low-frequency range,II.Higher frequency range:Journal of the Acoustical Society of America,28(2),168-191.
Deng,J.X.,Shi,G.,and Yu,J.,2003,The research of the characteristics of ultrasonic velocity dispersion in fluid saturated rock:Acta Scicentiarum Naturalum UniversitisPekinesis(in Chinese),39(6),835-843.
Dvorkin,J.,Mavko,G.,and Nur,A.,1995,Squirt-flow in fully saturated rocks:Geophysics,60(1),97-107.
Dvorkin,J.,Nolen-Hoeksema,R.,and Nur,A.,1994,The squirt-flow mechanism:Macroscopic description:Geophysics,59(3),428-438.
Dvorkin,J.,and Nur,A.,1993,Dynamic poroelasticity:A unifi ed model with the squirt and the Biot mechanisms:Geophysics,58(4),524-533.
Gassmann,F.,1951,über die Elastizitt porser Medien:Veirteljahrsschrift der Naturforschenden Gesellschaft in Zürich,96,1-23.
Geertsma,J.,and Smit,D.C.,1961,Some aspects of elastic wave propagation in fluid-saturated porous solids:Geophysics,26(2),169-181.
Gurevich,B.,2002,Effect of fluid viscosity on elastic wave attenuation in porous rocks:Geophysics,67(1),264-270.
Han,D.,and Batzle,M.,2000a,Velocity,density and modulus of hydrocarbon fluids-empirical modeling:SEG Technical Program Expanded Abstracts,19(1),1867-1870.
Han,D.,and Batzle,M.,2000b,Velocity,density and modulus of hydrocarbonfluids-data measurement:SEG Technical Program Expanded Abstracts,19(1),1862-1866.
Hornby,B.E.,1998,Experimental laboratory determination of the dynamic elastic properties of wet,drained shales:Journal of Geophysical Research,103(B12),29945-29964.
Khazanehdari,J.,and Sothcott,J.,2003,Variation in dynamic elastic shear modulus of sandstone upon fluid saturation and substitution:Geophysics,68(2),472-481.
Li,J.C.,Shi,G.,and Chen,S.Y.,2005,Experimental study on effects of viscosity and salinity of liquid on rock velocity anisotropy:Acta Scicentiarum Naturalum Universitis Pekinesis(in Chinese),41(6),851-858.
Mavko,G.,and Nur,A.,1975,Melt squirt in the asthenosphere:Journal of Geophysical Research,80,1444-1448.
Mavko,G.,and Jizba,D.,1991,Estimating grain-scale fluid effects on velocity dispersion in rocks:Geophysics,56(12),1940-1949.
Mavko,G.,Mukerji,T.,and Dvorkin,J.,2009,The rock physics handbook:Tools for seismic analysis in porous media(2nd edition):Cambridge University Press,New York,p.312.
Murphy,W.F.,1984,Acoustic measures of partial gas saturation in tight sandstones:Journal of Geophysical Research,89,11549-11559.
Murphy,W.F.,Winkler,K.W.,and Kleinberg,R.L.,1984,Frame modulus reduction in sedimentary rock:Geophysical Research Letters,11(9),805-808.
Nie,J.X.,and Yang,D.H.,2008,Viscoelastic BISQ model for low-permeability sandstone with clay:Chinese Physics Letters,25(8),3079-3082.
Nie,J.X.,Yang,D.H.,and Ba,J.,2010,Velocity dispersion and attenuation of waves in low-porosity-permeability anisotropic viscoelastic media with clay:Chinese Journal of Geophysics(in Chinese),53(2),385-392.
Nie,J.X.,Yang,D.H.,and Yang,H.Z.,2008,A generalized viscoelastic Biot/squirt model for clay-bearing sandstones in a wide range of permeabilities:Applied Geophysics,5(4),249-260.
O’Connell,R.J.,and Budiansky,B.,1977,Viscoelastic properties of fluid-saturated cracked solids:Journal of Geophysical Research,82,5719-5740.
Parra,J.O.,2000,Poroelastic model to relate seismic wave attenuation and dispersion to permeability anisotropy:Geophysics,65(1),202-210.
Peselnick,L.,and Outerbridge,W.F.,1961,Internal friction in shear and shear modulus of Solenhofen limestone over a frequency range of107cycles per second:Journal of Geophysical Research,66(2),581-588.
Shi,G.,and Yang,D.Q.,2002,Determination of the elastic wave velocities in porous rocks with the change of overburden pressure and its universal significance:Science in China,Ser.D,45(7),635-642.
Spencer,J.W.,1981,Stress relaxations at low frequenciesin fluid saturated rocks:Attenuation and modulusdispersion:Journal of Geophysical Research,86(B3),1803-1812.
Wang,Z.,and Nur,A.,1990,Dispersion analysis of acoustic velocities in rocks:The Journal of the Acoustical Society of America,87(6),2384-2395.
Wang,Z.,and Nur,A.M.,1988,Velocity dispersion and the“local flow’’mechanism in rocks:SEG Technical Program Expanded Abstracts,7(1),548-550.
Wei,X.C.,Lu,M.H.,Ba,J.,and Yang,H.Z.,2008,Dispersion and attenuation of elastic waves in a viscous fluid-saturated anisotropic porous solid:Chinese Journal of Geophysics(in Chinese),51(1),213-220.
Winkler,K.W.,1985,Dispersion analysis of velocity and attenuation in Berea sandstone:Journal of Geophysical Research,90,6793-6800.
Winkler,K.W.,1986,Estimates of velocity dispersion between seismic and ultrasonic frequencies:Geophysics,51(1),183-189.
Yang,D.H.,and Zhang,Z.J.,2002,Poroelastic wave equation including the Biot/squirt mechanism and the solid/?uid coupling anisotropy:Wave Motion,35(3),223-245.
Zhang,Y.Z.,Chu,Z.H.,Li,M.,and Luo,M.,2001,An experimental study of acoustic dispersion of rock and extrapolation of the velocity:Chinese Journal of Geophysics(in Chinese),44(1),136-141.
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