Modeling and analysis of azimuthal AVO responses from a viscoelastic anisotropic reflector
Guo Zhi-Qi1, Liu Xi-Wu2, Fu Wei1, and Li Xiang-Yang3,4
1. Geo-Exploration Science and Technology Institute, Jilin University, Changchun 130026, China.
2. Exploration & Production Research Institute, SINOPEC, Beijing 100083, China.
3. State Key Laboratory of Petroleum Resource and Prospecting, China University of Petroleum (Beijing), Beijing 102249, China.
4. CNPC Key Laboratory of Geophysical Prospecting, China University of Petroleum (Beijing), Beijing 102249, China.
Abstract：
We propose a method for modeling azimuthal AVO responses from a fractured reflector. The method calculates the integrated reflected wavetrains, and the wavetrains contain elastodynamic information including the contrast in impedance and anelasticity across interfaces, the internal anisotropic propagation, the dispersion and attenuation along the wave path, and tuning and interference. The results suggest that for large angles of incidence, the velocity dispersion and attenuation increase the amplitudes of PP waves from the top and decrease those from the bottom. For azimuthal responses at specific angles of incidence, the reflected wavetrains of PP waves tend to have longer duration with increasing azimuth. In contrast, model-converted PSV and PSH reflections show stable azimuthal features and are less affected by the reflector thickness. The amplitudes of PSV reflections increase with increasing azimuth; moreover, the waves have no reflection energy at 0° and 90° azimuth and maximum amplitude at 45° azimuth.
Guo Zhi-Qi,Liu Xi-Wu,Fu Wei et al. Modeling and analysis of azimuthal AVO responses from a viscoelastic anisotropic reflector[J]. APPLIED GEOPHYSICS, 2015, 12(3): 441-452.
[1]
Bakulin, A., Grechka, V., and Tsvankin, I., 2000a, Estimation of fracture parameters from reflection seismic data-Part I: HTI model due to a single fracture set: Geophysics, 65(6), 1788−1802.
[2]
Bakulin, A., Grechka, V., and Tsvankin, I., 2000b, Estimation of fracture parameters from reflection seismic data-Part II: Fractured models with orthorhombic symmetry: Geophysics, 65(6), 1803−1817.
[3]
Bakulin, A., Grechka, V., and Tsvankin, I., 2000c. Estimation of fracture parameters from reflectionseismic data-Part III: Fractured models with monoclinic symmetry: Geophysics, 65(6), 1818−1830.
[4]
Carcione, J. M., 1990, Wave propagation in anisotropic linear viscoelastic media: theory and simulated wavefields: Geophysical Journal International, 101, 739−750.
[5]
Carcione, J. M., 1995, Constitutive model and wave equations for linear, viscoelastic, anisotropic media: Geophysics, 60(2), 537−548.
[6]
Carcione, J. M., 1996, Wavefronts in dissipative anisotropic media: Comparison of the plane-wave theory with numerical modeling: Geophysics, 61(3), 857−861.
[7]
Carcione, J. M., 1997, Reflection and transmission of qP-qS plane waves at a plane boundary between viscoelastic transversely isotropic media: Geophysical Journal International, 129, 669−680.
[8]
Carcione, J. M., Helle, H. B., and Zhao, T., 1998, Effects of attenuation and anisotropy on reflection amplitude versus offset: Geophysics, 63(5), 1652−1658.
[9]
Carcione, J. M., 1999, Effects of vector attenuation on AVO of offshore reflections: Geophysics, 64(3), 815−819.
[10]
Carcione, J. M., 2001a, Amplitude variations with offset of pressure-seal reflections: Geophysics, 66(1), 283−293.
[11]
Carcione, J. M., 2001b, AVO effects of a hydrocarbon source-rock layer: Geophysics, 66(2), 419-427.
[12]
Chapman, M., 2003, Frequency dependent anisotropy due to meso-scale fractures in the presence of equant porosity: Geophysical Prospecting, 51(5), 369-379.
[13]
Chapman, M., Liu, E. and Li, X. Y., 2006, The influence of fluid-sensitive dispersion and attenuation on AVO analysis: Geophysical Journal International, 167(1), 89-105.
[14]
Far, M. E., Sayers, C. M., Thomsen, L., Han, D. and Castagna, J. P., 2013a, Seismic characterization of naturally fractured reservoirs using amplitude versus offset and azimuth analysis:Geophysical Prospecting, 61, 427-447.
[15]
Far, M. E., Thomsen, L., and Sayers, C. M., 2013b, Seismic characterization of naturally reservoirs with asymmetric fractures: Geophysics, 78(2), N1-N10.
[16]
Far, M. E., Hardage, B., and Wagner, D., 2014, Fracture parameter inversion for Marcellus Shale: Geophysics, 79(3), C55-C63.
[17]
Feng, S.,Zhu, X., Toksöz,M. N., 2002, Effects of fractures on NMO velocities and P-waveazimuthal AVOresponse: Geophysics, 67(3), 711-726.
[18]
Grechka, V.,Pech, A., and Tsvankin,I., 2005, Parameter estimation in orthorhombic media using multicomponent wide-azimuthreflection data: Geophysics, 70(2), D1-D8.
[19]
Guo, Z. Q., Liu, C., and Li, X. Y., 2015, Seismic signatures of reservoir permeability based on the patchy-saturation model: Applied Geophysics, 12(2), 187−198.
[20]
Hall, S. A., andKendall, J., 2003, Fracture characterization at Valhall: Application of P-wave amplitude variation with offset andazimuth(AVOA) analysis to a 3D ocean-bottom data set: Geophysics, 68(4), 1150-1160.
[21]
Hudson, J. A., 1981, Wave speeds and attenuation of elastic waves in material containing cracks: Geophysical Journal of the Royal Astronomical Society, 64(1), 133−150.
[22]
Hudson, J. A., 1986, A higher order approximation to the wave propagation constants for a cracked solid: Geophysical Journal of the Royal Astronomical Society, 87(1), 265−274.
[23]
Hudson, J. A., 1991, Crack distributions which account for a given seismic anisotropy: Geophysical Journal International, 104(3), 517−521.
[24]
Ling, Y., Han, L. G., and Zhang, Y. M., 2014, Viscoelastic characteristic of low-frequency seismic wave attenuation in porous media: Applied Geophysics, 11(4), 355−363.
[25]
MacBeth, C., 1999, Azimuthalvariation inP-wave signatures due to fluid flow: Geophysics, 64(4), 1181-1192.
[26]
Mallick, S. and Frazer, L. N., 1991, Reflection/transmission coefficients and azimuthal anisotropy in marine seismic studies: Geophysical Journal International, 105, 241-252.
[27]
Martin, L., 2007, Seismic critical-angle reflectometry: A method to characterize azimuthal anisotropy: Geophysics, 72(3), D41-D50.
[28]
Ostrander, W. J., 1984, Plane-wave reflection coefficients for gas sands at nonnormal angles of incidence: Geophysics, 49(10), 1637-1648.
[29]
Pérez, M. A,. Gibson, R. L., and Toksöz, M. N., 1999, Detection of fracture orientation using azimuthal variation of P-wave AVO responses: Geophysic, 64(4), 1253-1265.
[30]
Quintal, B., Schmalholz, S. M., and Podladchikov, Y., 2009, Low-frequency reflections from a thin layer with high attenuation caused by interlayer flow: Geophysics, 74(1), N15-N23.
[31]
Quintal, B., Schmalholz, S. M., and Podladchikov, Y., 2011, Impact of fluid saturation on the reflection coefficient of a poroelastic layer: Geophysics, 76(2), N1-N12.
[32]
Rüger, A., 1997, P-wave reflection coefficients for transversely isotropic media with vertical and horizontal axis of symmetry: Geophysics, 62, 713-722.
[33]
Rüger, A., 1998, Variation ofP-wave reflectivity with offset andazimuthin anisotropic media: Geophysics, 63(3), 935-947.
[34]
Rutherford, S. R., and Williams, R. H., 1989, Amplitude-versus-offset variations in gas sands: Geophysics, 54, 680-688.
[35]
Sayers, C. M., and Kachanov, M., 1991, A simple technique for finding effective elastic constants of cracked solids for arbitrary crack orientation statistics: International Journal of Solids and Structures, 27, 671-680.
[36]
Sayers, C. M., and Kachanov, M., 1995, Microcrack-induced elastic wave anisotropy of brittle rocks: Journal of Geophysical Research, 100, 4149-4156.
[37]
Sayers, C. M., and Rickett, J. E., 1997, Azimuthal variation in AVO response for fractured gas sands: Geophysical Prospecting, 45, 165-182.
[38]
Schoenberg, M., and Douma, J., 1988, Elastic wave propagation in media with parallel fractures and aligned cracks: Geophysical Prospecting, 36(6), 571-590.
[39]
Schoenberg, M. A., and Protázio, J., 1992, ‘Zoeppritz’ rationalized and generalized to anisotropy: Journal of Seismic Exploration, 1, 125-144.
[40]
Schoenberg, M., and Helbig, K., 1997, Orthorhombic media: modeling elastic wave behavior in a vertically fractured earth: Geophysics, 62(6), 1954-1974.
[41]
Schoenberg, M. A., Dean, S., and Sayers, C. M., 1999, Azimuth-dependent tuning of seismic waves reflected from fractured reservoirs: Geophysics, 64(4), 1160-1171.
[42]
Vavrycuk, V., Psencik, I., 1998, PP-wave reflection coefficients in weakly anisotropic elastic media: Geophysics, 63(6), 2129-2141.
[43]
Yan, J., and Tsvankin, I., 2008, AVO-sensitive semblance analysis for wide-azimuth data: Geophysics, 73(2), U1-U11.
2015, Vol. 12 
