多组垂直裂缝诱导各向异性的HTI近似及其特征分析
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摘要
在裂缝诱导各向异性理论研究中通常使用等效HTI介质来近似多组裂缝所引起的综合效应.由于构造运动的复杂性,多组裂缝普遍存在于地壳与油气储层中.为了研究多组裂缝的地震属性特征,分析常用的等效HTI模型对于多组裂缝近似精度及附加裂缝对介质属性特征的影响,本文利用线性滑移模型进行了多组垂直裂缝的单斜各向异性等效介质理论计算,并利用空间搜索方法求取与其最为接近的HTI介质各向异性弹性参数.重点研究了在两种各向异性介质中纵波速度、快慢横波速度和极化特征及其差异,量化分析附加裂缝对于地震属性如速度、极化方向和走时等的影响,研究对附加裂缝敏感的地震属性.此研究结果和方法为进一步研究多组裂缝的反演及识别方法提供基础,同时对于将高阶对称性各向异性介质中已存在的计算方法应用于低阶对称性时的适用程度、精度分析及相关方法研究具有重要作用.
Equivalent HTI medium is commonly used to approximate combined effects of multiple groups of fractures in theoretical study of fracture-induced anisotropy.Due to complex tectonic movement,multiple sets of fractures are prevailed in crust and oil and gas reservoirs.In order to study the seismic attributes and analyze the approximation accuracy of the equivalent HTI model for multiple sets of fractures,this study uses a linear slip model of the equivalent medium theory to calculate the monoclinic anisotropy for multiple sets of fractures and obtain the closest equivalent anisotropic elastic parameters of the HTI medium by scanning the shortest spatialdistance.The differences in P wave velocity,fast and low shear wave velocity and polarization characteristics of the two types of anisotropic media are discussed in detail and quantitative analysis of the effects of additional cracks on seismic attributes such as velocity,polarization direction and travel time is conducted to find the most sensitive attribute to the existence of additional fractures.The results provide a basis for development of inversion methods of multiple sets of fractures and play an important role in the applicability,precision analysis and research on application of relevant existing methods as the high-order anisotropic symmetry is used to approximated the low-order symmetry.
Equivalent HTI medium is commonly used to approximate combined effects of multiple groups of fractures in theoretical study of fracture-induced anisotropy.Due to complex tectonic movement,multiple sets of fractures are prevailed in crust and oil and gas reservoirs.In order to study the seismic attributes and analyze the approximation accuracy of the equivalent HTI model for multiple sets of fractures,this study uses a linear slip model of the equivalent medium theory to calculate the monoclinic anisotropy for multiple sets of fractures and obtain the closest equivalent anisotropic elastic parameters of the HTI medium by scanning the shortest spatialdistance.The differences in P wave velocity,fast and low shear wave velocity and polarization characteristics of the two types of anisotropic media are discussed in detail and quantitative analysis of the effects of additional cracks on seismic attributes such as velocity,polarization direction and travel time is conducted to find the most sensitive attribute to the existence of additional fractures.The results provide a basis for development of inversion methods of multiple sets of fractures and play an important role in the applicability,precision analysis and research on application of relevant existing methods as the high-order anisotropic symmetry is used to approximated the low-order symmetry.
引文
Arts R J,Helbig K,Rasolofosaon P N J.1991.General anisotropic elastic tensor in rocks,approximation,invariants,and particular directions.∥61st Ann.Internat Mtg.,Soc.Expi.Geophys..Expanded Abstracts,1534-1537.
Bakulin A V,Grechka V,Tsvankin I.2000.Estimation of fracture parameters from reflection seismic data-Part I:HTI models due to a single fracture set.Geophysics,65(6):1788-1802.
Browaeys J T,Chevrot S.2004.Decomposition of the elastic tensor and geophysical applications.Geophysical Journal International,159(2):667-678.
Contreras P,Grechka V,Tsvankin I.1999.Moveout inversion of P-wave data for horizontal transverse isotropy.Geophysics,64(4):1219-1229.
Cowin S C,Mehrabadi M M.1987.On the identification of material symmetry for anisotropic elastic materials.The Quarterly Journal of Mechanics and Applied Mathematics,40(4):451-476.
Dellinger J.2005.Computing the optimal transversely isotropic approximation of a general elastic tensor.Geophysics,70(5):I1-I10.
Den Boer L D.2014.An efficient algorithm for computing nearest medium approximations to an arbitrary anisotropic stiffness tensor.Geophysics,79(3):C81-C90.
Duan W S,Li F,Wang Y C,et al.2013.Offset vector tile for wide azimuth seismic processing.Oil Geophysical Prospecting(in Chinese),48(2):206-213.
Far M E,Sayers C M,Thomsen L,et al.2013.Seismic characterization of naturally fractured reservoirs using amplitude versus offset and azimuth analysis.Geophysical Prospecting,61(2):427-447.
Far M E,Hardage B,Wagner D.2014.Fracture parameter inversion for Marcellus shale.Geophysics,79(3):C55-C63.
Fedorov F I.1968.Theory of Elastic Waves in Crystals.New York:Springer.
Gajewski D,P2en9ik I.1987.Computation of high-frequency seismic wavefields in 3-D laterally inhomogeneous anisotropic media.Geophysical Journal International,91(2):383-411.
Gao Y,Wu J.2008.Compressive stress field in the crust deduced from shear-wave anisotropy:an example in capital area of China.Chinese Science Bulletin,53(18):2840-2848.
Grechka V,Contreras P,Tsvankin I.2000.Inversion of normal moveout for monoclinic media.Geophysical Prospecting,48(3):577-602.
Hao C T,Yao C.2014.Tele-seismic PS-wave splitting from the basement in the Capital area of China.Chinese Journal of Geophysics(in Chinese),57(8):2573-2583,doi:10.6038/cjg20140817.
Helbig K.1994.Foundations of Anisotropy for Exploration Seismics.Oxford:Elsevier Science Ltd.
Hudson J A.1981.Overall properties of a cracked solid.Mathematical Proceedings of the Cambridge Philosophical Society,88(2):371-384.
Hudson J A.1986.A higher order approximation to the wave propagation constants for a cracked solid.Geophysical Journal International,87(1):265-274.
Jenner E.2011.Combining VTI and HTI anisotropy in prestack time migration:Workflow and data examples.The Leading Edge,30(7):732-739.
Li L,Hao C T.2012.Feasibility to neglect the tilt of the symmetry axis of a TTI medium.Chinese Journal of Geophysics(in Chinese),55(6):2004-2013,doi:10.6038/j.issn.0001-5733.2012.06.022.
Liu E,Crampin S,Queen J H,et al.1993.Behaviour of shear waves in rocks with two sets of parallel cracks.Geophysical Journal International,113(2):509-517.
Liu E R,Hudson J A,Pointer T.2000.Equivalent medium representation of fractured rock.Journal of Geophysical Research:Solid Earth,105(B2):2981-3000.
Liu E R,Yue J H,Pan D M.2006.Frequency-dependent anisotropy:Effects of multiple fracture sets on shear-wave polarisations.Chinese Journal of Geophysics(in Chinese),49(5):1401-1409.
Lubbe R,Sothcott J,Worthington M H,et al.2008.Laboratory estimates of normal and shear fracture compliance.Geophysical Prospecting,56(2):239-247.
Mainprice D.1990.A FORTRAN program to calculate seismic anisotropy from the lattice preferred orientation of minerals.Computers&Geosciences,16(3):385-393.
Sayers C M,Kachanov M.1995.Microcrack-induced elastic wave anisotropy of brittle rocks.Journal of Geophysical Research:Solid Earth,100(B3):4149-4156.
Sayers C M.1998.Misalignment of the orientation of fractures and the principal axes for P and S waves in rocks containing multiple non-orthogonal fracture sets.Geophysical Journal International,133(2):459-466.
Sayers C M,Taleghani A D,Adachi J.2009.The effect of mineralization on the ratio of normal to tangential compliance of fractures.Geophysical Prospecting,57(3):439-446.
Schoenberg M,Sayers C M.1995.Seismic anisotropy of fractured rock.Geophysics,60(1):204-211.
Song L T,Wang Y,Liu Z H,et al.2015.Elastic anisotropy characteristics of tight sands under different confining pressures and fluid saturation states.Chinese Journal of Geophysics(in Chinese),58(9):3401-3411,doi:10.6038/cjg20150932.
Tsvankin I.1997.Anisotropic parameters and P-wave velocity for orthorhombic media.Geophysics,62(4):1292-1309.
Vinje V,Zhao P,Gaiser J.2015.Offset vector tile gather extension and weighting to reduce footprint in dual-datum and convertedwave migration.∥85th Ann.Internat Mtg.,Soc.Expi.Geophys..Expanded Abstracts,1534-1537.
Walker A M,Wookey J.2012.MSAT-A new toolkit for the analysis of elastic and seismic anisotropy.Computers&Geosciences,49:81-90.
Wang Y,Shi Y,Yang D Y.2008.Application of the weakness ratio in fracture medium fluid detection.Chinese Journal of Geophysics(in Chinese),51(4):1152-1155.
Wang Y,Liu Y Y,Zhang M G.2017.Seismic Equivalent Medium Theory for Fractured Anisotropy.Beijing:Science Press.
Winterstein D F.1990.Velocity anisotropy terminology for geophysicists.Geophysics,55(8):1070-1088.
Zhang J L,Wang Y,Lu J.2013.A new algorithm for frequencydependent shear-wave splitting parameters extraction.Journal of Geophysics and Engineering,10(5):055005.
Zheng X Y.2007.Identification of symmetry planes in weakly anisotropic elastic media.Geophysical Journal International,170(1):468-478.
段文胜,李飞,王彦春等.2013.面向宽方位地震处理的炮检距向量片技术.石油地球物理勘探,48(2):206-213.
高原,吴晶.2008.利用剪切波各向异性推断地壳主压应力场:以首都圈地区为例.科学通报,53(23):2933-2939.
郝重涛,姚陈.2014.首都圈地区远震基底波PS波分裂研究.地球物理学报,57(8):2573-2583,doi:10.6038/cjg20140817.
李磊,郝重涛.2012.忽略TTI介质对称轴倾角的可行性.地球物理学报,55(6):2004-2013,doi:10.6038/j.issn.0001-5733.2012.06.022.
刘恩儒,岳建华,潘冬明.2006.地震各向异性——多组裂隙对横波偏振的影响.地球物理学报,49(5):1401-1409.
宋连腾,王赟,刘忠华等.2015.不同围压和流体饱和状态下致密砂岩弹性各向异性特征.地球物理学报,58(9):3401-3411,doi:10.6038/cjg20150932.
王赟,石瑛,杨德义.2008.弱度比在裂隙含流体检测中的应用.地球物理学报,51(4):1152-1155.
王赟,刘媛媛,张美根.2017.裂缝各向异性地震等效介质理论.北京:科学出版社.
Bakulin A V,Grechka V,Tsvankin I.2000.Estimation of fracture parameters from reflection seismic data-Part I:HTI models due to a single fracture set.Geophysics,65(6):1788-1802.
Browaeys J T,Chevrot S.2004.Decomposition of the elastic tensor and geophysical applications.Geophysical Journal International,159(2):667-678.
Contreras P,Grechka V,Tsvankin I.1999.Moveout inversion of P-wave data for horizontal transverse isotropy.Geophysics,64(4):1219-1229.
Cowin S C,Mehrabadi M M.1987.On the identification of material symmetry for anisotropic elastic materials.The Quarterly Journal of Mechanics and Applied Mathematics,40(4):451-476.
Dellinger J.2005.Computing the optimal transversely isotropic approximation of a general elastic tensor.Geophysics,70(5):I1-I10.
Den Boer L D.2014.An efficient algorithm for computing nearest medium approximations to an arbitrary anisotropic stiffness tensor.Geophysics,79(3):C81-C90.
Duan W S,Li F,Wang Y C,et al.2013.Offset vector tile for wide azimuth seismic processing.Oil Geophysical Prospecting(in Chinese),48(2):206-213.
Far M E,Sayers C M,Thomsen L,et al.2013.Seismic characterization of naturally fractured reservoirs using amplitude versus offset and azimuth analysis.Geophysical Prospecting,61(2):427-447.
Far M E,Hardage B,Wagner D.2014.Fracture parameter inversion for Marcellus shale.Geophysics,79(3):C55-C63.
Fedorov F I.1968.Theory of Elastic Waves in Crystals.New York:Springer.
Gajewski D,P2en9ik I.1987.Computation of high-frequency seismic wavefields in 3-D laterally inhomogeneous anisotropic media.Geophysical Journal International,91(2):383-411.
Gao Y,Wu J.2008.Compressive stress field in the crust deduced from shear-wave anisotropy:an example in capital area of China.Chinese Science Bulletin,53(18):2840-2848.
Grechka V,Contreras P,Tsvankin I.2000.Inversion of normal moveout for monoclinic media.Geophysical Prospecting,48(3):577-602.
Hao C T,Yao C.2014.Tele-seismic PS-wave splitting from the basement in the Capital area of China.Chinese Journal of Geophysics(in Chinese),57(8):2573-2583,doi:10.6038/cjg20140817.
Helbig K.1994.Foundations of Anisotropy for Exploration Seismics.Oxford:Elsevier Science Ltd.
Hudson J A.1981.Overall properties of a cracked solid.Mathematical Proceedings of the Cambridge Philosophical Society,88(2):371-384.
Hudson J A.1986.A higher order approximation to the wave propagation constants for a cracked solid.Geophysical Journal International,87(1):265-274.
Jenner E.2011.Combining VTI and HTI anisotropy in prestack time migration:Workflow and data examples.The Leading Edge,30(7):732-739.
Li L,Hao C T.2012.Feasibility to neglect the tilt of the symmetry axis of a TTI medium.Chinese Journal of Geophysics(in Chinese),55(6):2004-2013,doi:10.6038/j.issn.0001-5733.2012.06.022.
Liu E,Crampin S,Queen J H,et al.1993.Behaviour of shear waves in rocks with two sets of parallel cracks.Geophysical Journal International,113(2):509-517.
Liu E R,Hudson J A,Pointer T.2000.Equivalent medium representation of fractured rock.Journal of Geophysical Research:Solid Earth,105(B2):2981-3000.
Liu E R,Yue J H,Pan D M.2006.Frequency-dependent anisotropy:Effects of multiple fracture sets on shear-wave polarisations.Chinese Journal of Geophysics(in Chinese),49(5):1401-1409.
Lubbe R,Sothcott J,Worthington M H,et al.2008.Laboratory estimates of normal and shear fracture compliance.Geophysical Prospecting,56(2):239-247.
Mainprice D.1990.A FORTRAN program to calculate seismic anisotropy from the lattice preferred orientation of minerals.Computers&Geosciences,16(3):385-393.
Sayers C M,Kachanov M.1995.Microcrack-induced elastic wave anisotropy of brittle rocks.Journal of Geophysical Research:Solid Earth,100(B3):4149-4156.
Sayers C M.1998.Misalignment of the orientation of fractures and the principal axes for P and S waves in rocks containing multiple non-orthogonal fracture sets.Geophysical Journal International,133(2):459-466.
Sayers C M,Taleghani A D,Adachi J.2009.The effect of mineralization on the ratio of normal to tangential compliance of fractures.Geophysical Prospecting,57(3):439-446.
Schoenberg M,Sayers C M.1995.Seismic anisotropy of fractured rock.Geophysics,60(1):204-211.
Song L T,Wang Y,Liu Z H,et al.2015.Elastic anisotropy characteristics of tight sands under different confining pressures and fluid saturation states.Chinese Journal of Geophysics(in Chinese),58(9):3401-3411,doi:10.6038/cjg20150932.
Tsvankin I.1997.Anisotropic parameters and P-wave velocity for orthorhombic media.Geophysics,62(4):1292-1309.
Vinje V,Zhao P,Gaiser J.2015.Offset vector tile gather extension and weighting to reduce footprint in dual-datum and convertedwave migration.∥85th Ann.Internat Mtg.,Soc.Expi.Geophys..Expanded Abstracts,1534-1537.
Walker A M,Wookey J.2012.MSAT-A new toolkit for the analysis of elastic and seismic anisotropy.Computers&Geosciences,49:81-90.
Wang Y,Shi Y,Yang D Y.2008.Application of the weakness ratio in fracture medium fluid detection.Chinese Journal of Geophysics(in Chinese),51(4):1152-1155.
Wang Y,Liu Y Y,Zhang M G.2017.Seismic Equivalent Medium Theory for Fractured Anisotropy.Beijing:Science Press.
Winterstein D F.1990.Velocity anisotropy terminology for geophysicists.Geophysics,55(8):1070-1088.
Zhang J L,Wang Y,Lu J.2013.A new algorithm for frequencydependent shear-wave splitting parameters extraction.Journal of Geophysics and Engineering,10(5):055005.
Zheng X Y.2007.Identification of symmetry planes in weakly anisotropic elastic media.Geophysical Journal International,170(1):468-478.
段文胜,李飞,王彦春等.2013.面向宽方位地震处理的炮检距向量片技术.石油地球物理勘探,48(2):206-213.
高原,吴晶.2008.利用剪切波各向异性推断地壳主压应力场:以首都圈地区为例.科学通报,53(23):2933-2939.
郝重涛,姚陈.2014.首都圈地区远震基底波PS波分裂研究.地球物理学报,57(8):2573-2583,doi:10.6038/cjg20140817.
李磊,郝重涛.2012.忽略TTI介质对称轴倾角的可行性.地球物理学报,55(6):2004-2013,doi:10.6038/j.issn.0001-5733.2012.06.022.
刘恩儒,岳建华,潘冬明.2006.地震各向异性——多组裂隙对横波偏振的影响.地球物理学报,49(5):1401-1409.
宋连腾,王赟,刘忠华等.2015.不同围压和流体饱和状态下致密砂岩弹性各向异性特征.地球物理学报,58(9):3401-3411,doi:10.6038/cjg20150932.
王赟,石瑛,杨德义.2008.弱度比在裂隙含流体检测中的应用.地球物理学报,51(4):1152-1155.
王赟,刘媛媛,张美根.2017.裂缝各向异性地震等效介质理论.北京:科学出版社.