ARTICLE

Elastic impedance parameterization and inversion in a vertical, rotationally invariant fractured HTI medium

XINPENG PAN1 GUANGZHI ZHANG1,2 HUAIZHEN CHEN3 XINGYAO YIN1,2
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1 School of Sciences, China University of Petroleum (Huadong), Qingdao, Shandong, P.R. China. parxinpeng1990@gmail.com,
2 Laboratory for Marine Mineral Resources, Qingdao National Laboratory for Marine Science and Technology, Qingdao, Shandong, P.R. China.,
3 Department of Geoscience, University of Calgary, Calgary, Alberta, Canada.,
JSE 2018, 27(3), 227–254;
Submitted: 7 October 2016 | Accepted: 2 March 2018 | Published: 1 June 2018
© 2018 by the Authors. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution -Noncommercial 4.0 International License (CC-by the license) ( https://creativecommons.org/licenses/by-nc/4.0/ )
Abstract

Pan, X.P., Zhang, G.Z., Chen, H.Z. and Yin, X.Y., 2018. Elastic impedance parameterization and inversion in a vertical, rotationally invariant fractured HTI medium. Journal of Seismic Exploration, 27: 227-254. Seismic wave propagating in a purely isotropic background medium containing a single set of vertically aligned fractures exhibits a long-wavelength effective transversely isotropy (HTI) with a horizontal symmetry axis. The estimation of fracture weaknesses is significant for the characterization of anisotropy in a fracture-induced HTI medium. Our goal is to demonstrate an azimuthal elastic impedance inversion approach for fracture characterization by utilizing the observable wide-azimuth seismic reflection data in a vertical, rotationally invariant fractured reservoir. Under the assumption of weak contrast across the interface and weak anisotropy, we first derive the perturbations in elastic stiffness parameters of a weakly HTI medium. Then we derive a linearized PP-wave reflection coefficient in terms of P- and S-wave moduli, density, and fracture weaknesses for the case of a weak-contrast interface separating two weakly HTI media based on the perturbation matrix and scattering function. Using the least square ellipse fitting (LSEF) method to calculate the azimuth of fracture normal, we build a perfect linear relationship between the reflection coefficient and fracture weaknesses. Finally, we propose a novel parameterization method for fracture weaknesses, and derive the elastic impedance variation with angles of incidence and azimuth (EIVAZ) equation. In order to refine the inversion stability and lateral continuity, we implement the EIVAZ inversion in a Bayesian framework incorporating the Cauchy-sparse regularization and the low-frequency information regularization, and the nonlinear iteratively reweighted least squares (IRLS) strategy is employed to solve the linear inversion problem. A test on a real data set indicates that the estimated results agree well with the well log interpretation, and the proposed method appears to generate reliable results for the characterization of fractured reservoirs.

Keywords
fracture-induced HTI medium
rotationally invariant fractures
weak-contrast and weak-anisotropy assumption
quasi-weakness parameters
EIVAZ inversion
References
  1. Alemie, W. and Sacchi, M.D., 2011. High-resolution three-term AVO inversion bymeans of a Trivariate Cauchy probability distribution. Geophysics, 76: R43-R55.
  2. Bakulin, A., Grechka, V. and Tsvankin, I., 2000. Estimation of fracture parameters fromreflection seismic data-Part 1: HTI model due to a single fracture set. Geophysics, 65:1788-1802.
  3. Bissantz, N., Diimbgen, L., Munk, A. and Stratmann, B., 2009. Convergence analysis ofgeneralized iteratively reweighted least squares algorithms on convex functionspaces. J. Optimizat., 19: 1828-1845.
  4. Buland, A. and Omre, H., 2003. Bayesian linearized AVO inversion. Geophysics, 68:185-198.
  5. Burns, D.R., Willis, M.E., Tokséz, M.N., Vetri, L. and Donato, S., 2007. Fractureproperties from seismic scattering. The Leading Edge, 26: 1186-1196.
  6. Burridge, R., de Hoop, M.V., Miller, D. and Spencer, C., 1998. Multiparameter inversionin anisotropic media. Geophys. J. Internat., 134: 757-777.
  7. Cerveny, V., 2001. Seismic Ray Theory. Cambridge University Press, Cambridge.
  8. Chen, H. , Zhang, G., Chen, J. and Yin, X., 2014. Fracture filling fluids identificationusing azimuthally elastic impedance based on rock physics. J. Appl. Geophys., 110:98-105.
  9. Chen, H., Zhang, G., Ji, Y. and Yin, X., 2017. Azimuthal seismic amplitude differenceinversion for fracture weakness. Pure Appl. Geophys., 174: 279-291.
  10. Connolly, P., 1999, Elastic impedance. The Leading Edge, 18: 438-452.
  11. Daubechies, I., DeVore, R., Fornasier, M. and Giintiirk, C.S., 2010. Iterativelyreweighted least squares minimization for sparse recovery. Communic. Pure Appl.Mathemat., 63: 1-38.
  12. Dolberg, D.M., Helgesen, J., Hanssen, T.H., Magnus, I., Saigal, G. and Pedersen, B.K.,
  13. Porosity prediction from seismic inversion, Lavrans Field, Halten Terrace,Norway. The Leading Edge, 19: 392-399.
  14. Downton, J., 2005. Seismic Parameter Estimation from AVO Inversion. Ph.D. Thesis,University of Calgary.
  15. Eaton, D.W.S. and Stewart, R., 1994. Migration/inversion for transversely isotropicelastic media. Geophys. J. Internat., 119: 667-683.
  16. Grechka, V., Bakulin, A. and Tsvankin, I., 2003. Seismic characterization of verticalfractures described as general linear slip interfaces. Geophys. Prosp., 51: 117-129.
  17. Helgesen, J., Magnus, I., Prosser, S., Saigal, G., Aamodt, G., Dolberg, D. and Busman, S.,
  18. Comparison of constrained sparse spike and stochastic inversion for porosityprediction at Kristin Field. The Leading Edge, 19: 400-407.
  19. Hsu, C.J. and Schoenberg, M., 1993. Elastic waves through a simulated fracturedmedium. Geophysics, 58: 964-977.
  20. Jenner, E., 2002. Azimuthal AVO: Methodology and data examples. The Leading Edge,21: 782-786.
  21. Liu, E. and Martinez, A., 2012. Seismic fracture characterization : Concepts and practicalapplications. EAGE, Houten, The Netherlands.
  22. Mahmoudian, F. and Margrave, G.F., 2012. AVAZ inversion for fracture orientation andintensity: a physical modeling study. Extended Abstr., 74th EAGE Conf.,Copenhagen.
  23. Martins, J.L., 2006. Elastic impedance in weakly anisotropic media. Geophysics, 71:2092-2096.
  24. Narr, W., Schechter, W.S. and Thompson, L., 2006. Naturally fractured reservoircharacterization: SPE monograph, Richardson, TX, USA.
  25. Pan, X., Zhang, G., Chen, H. and Yin, X., 2017a. McMC-based AVAZ direct inversionfor fracture weaknesse. J. Appl. Geophys., 138: 50-61.
  26. Pan, X., Zhang, G., Chen, H. and Yin, X., 2017b. McMC-based nonlinear EIVAZinversion driven by rock physics. J. Geophys. Engineer., 14: 368-379.
  27. PSenéik, I. and Gajewski, D., 1998. Polarization, phase velocity and NMO velocity of qPwaves in arbitrary weakly anisotropic media. Geophysics, 63: 1754-1766.
  28. PSen¢ik, I. and Vavryéuk, V., 1998. Weak contrast PP-wave displacement R/Tcoefficients in weakly anisotropic elastic media. Pure Appl. Geophys., 151: 699-718.
  29. PSencik, I. and Martins, J.L., 2001. Properties of weak contrast PP reflection/transmission coefficients for weakly anisotropic elastic media. Studia Geophys.Geodaet., 45: 176-199.
  30. Riiger, A., 1997. P-wave reflection coefficients for transversely isotropic models withvertical and horizontal axis of symmetry. Geophysics, 62: 713-722.
  31. Riiger, A., 1998. Variation of P-wave reflectivity with offset and azimuth in anisotropicmedia. Geophysics, 63: 935-947.
  32. Sacchi, M.D. and Ulrych, T.J., 1995. High-resolution velocity gathers and offset spacereconstruction. Geophysics, 60: 1169-1177.
  33. Scales, J.A. and Smith, M.L., 2000. Introductory Geophysical Inverse Theory (draft).Samizdat Press, Golden, CO.
  34. Schoenberg, M., 1980. Elastic wave behavior across linear slip interfaces. J. AcousticalSoc. Am., 68: 1516-1521.
  35. Schoenberg, M., 1983. Reflection of elastic waves from periodically stratified media withinterfacial slip. Geophys. Prosp., 31: 265-292.
  36. Schoenberg, M. and Sayers, C.M., 1995. Seismic anisotropy of fractured rock.Geophysics, 60: 204-211.
  37. Shaw, R.K. and Sen, M.K., 2004. Born integral, stationary phase and linearized reflectioncoefficients in weak anisotropic media. Geophys. J. Internat., 158: 225-238.
  38. Shaw, R.K. and Sen, M.K., 2006. Use of AVOA data to estimate fluid indicator in avertically fractured medium. Geophysics, 71: C15-C24.
  39. Stolt, R.H. and Weglein, A.B., 1985. Migration and inversion of seismic data.Geophysics, 50: 2458-2472.
  40. Thomsen, L., 1986, Weak elastic anisotropy. Geophysics, 51: 1954-1966.
  41. Thomsen, L., 2002. Understanding seismic anisotropy in exploration and exploitation.
  42. SEG 2010 Disting. Instruct. Series, Vol. 5. SEG, Tulsa, OK.
  43. Tsvankin, L., 1996. P-wave signatures and notation for transversely isotropic media: anoverview. Geophysics, 61: 467-483.
  44. Tsvankin, L. and Grechka, V., 2011. Seismology of Azimuthally Anisotropic Media and
  45. Seismic Fracture Characterization. SEG, Tulsa, OK.
  46. Whitcombe, D.N., 2002. Elastic impedance normalization. Geophysics, 67: 60-62.
  47. Yin, X., Zong, Z. and Wu, G., 2013. Seismic wave scattering inversion for fluid factor ofheterogeneous media. Sci. China: Earth Sci., 43: 1934-1942.
  48. Zong, Z., Yin, X. and Wu, G., 2012. AVO inversion and poroelasticity with P- andS-wave moduli. Geophysics, 77: 29-36.
  49. Zong, Z., Yin, X. and Wu, G., 2013. Elastic impedance parameterization and inversionwith Young’s modulus and Poisson’s ratio. Geophysics, 78: N35-42.
  50. Zong, Z., Yin, X., Wu, G. and Wu, Z.P., 2015. Elastic inverse scattering for fluidvariation with time-lapse seismic data. Geophysics, 80: WA61-WA67.
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Journal of Seismic Exploration, Electronic ISSN: 0963-0651 Print ISSN: 0963-0651, Published by AccScience Publishing