none 10.1190/geo2011-0259.1 Society of Exploration Geophysicists Society of Exploration Geophysicists 186 56029095 5981 2025121115260109300 10.1190 2025-12-11T20:26:11Z 2012-06-14T18:25:09Z 27 Geophysics 1942-2156 0016-8033 07 1 2012 07 01 2012 77 4 Feng Zhang China University of Petroleum 1 , Department of Geophysical Prospecting, State Key Laboratory of Petroleum Resource and Prospecting, Beijing, ; , Department of Earth Science and Engineering, Center for Reservoir Geophysics, London, E-mail: f.zhang717@googlemail.com . China U. K. Imperial College London 1 , Department of Geophysical Prospecting, State Key Laboratory of Petroleum Resource and Prospecting, Beijing, ; , Department of Earth Science and Engineering, Center for Reservoir Geophysics, London, E-mail: f.zhang717@googlemail.com . China U. K. Yanghua Wang Imperial College London 2 , Department of Earth Science and Engineering, Center for Reservoir Geophysics, London, . E-mail: yanghua.wang@imperial.ac.uk . U. K Xiang-Yang Li China University of Petroleum 3 , Department of Geophysical Prospecting, State Key Laboratory of Petroleum Resource and Prospecting, Beijing, ; , British Geological Survey, Edinburgh, . E-mail: xyl@bgs.ac.uk . China U. K University of Edinburgh 3 , Department of Geophysical Prospecting, State Key Laboratory of Petroleum Resource and Prospecting, Beijing, ; , British Geological Survey, Edinburgh, . E-mail: xyl@bgs.ac.uk . China U. K ABSTRACT Theoretical evaluation of the elastic impedance (EI) and the ray impedance (RI) reveals that RI has a more reliable value range and is less sensitive to noise than EI. We devised a new measurement RI˜ to estimate the ray impedance from elastic impedance derived by existing techniques. The recovered RI˜ was expressed in the form of a normalization of EI. It solved the range variability problem of EI and had the same interpretation capability as RI. In addition, reflection coefficients represented by RI˜ showed good agreement with the Zeoppritz equation even at postcritical angle of incidence. Tests of these three attributes (RI, RI˜, and EI) were performed on the log data of three different types of reservoir: a typical Class III marine gas-sand, a Class I tight gas-sand, and a Class II oil-bearing sand in thin sand-mud interbedded layers. Although the crossplots of EI against acoustic impedance (AI) showed visually similar characteristics for a gas-sand as that of RI, based on the linear/quadratic discrimination analysis, RI appeared to be more applicable than EI for characterizing gas sands, especially tight gas sands. RI˜, estimated from EI, had a comparable value range to the AI, and retained the interpretation ability of the original RI. Application on real seismic data showed that existing EI inversion results could be improved straightforwardly by means of the introduced transformation. 07 1 2012 07 01 2012 06 14 2012 M39 M52 10.1190/geo2011-0259.1 https://pubs.geoscienceworld.org/geophysics/article/77/4/M39/308407/Viabilities-of-seismic-ray-impedance-and-elastic https://pubs.geoscienceworld.org/seg/geophysics/article-pdf/77/4/M39/3227417/geo2011-0259.pdf https://pubs.geoscienceworld.org/seg/geophysics/article-pdf/77/4/M39/3227417/geo2011-0259.pdf http://geophysics.geoscienceworld.org/cgi/doi/10.1190/geo2011-0259.1 Quantitative seismology: Theory and methods Aki 1980 Quantitative seismic interpretation Avseth 2005 10.1017/CBO9780511600074 0016-8025 Geophysical Prospecting Bortfeld 9 1961 10.1111/gpr.1961.9.issue-4 Approximation to the reflection and transmission coefficients of plane longitudinal and transverse waves 1070-485X The Leading Edge Connolly 18 1999 10.1190/1.1438307 Elastic impedance 1742-2132 Journal of Geophysics and Engineering Gan 6 2009 10.1088/1742-2132/6/1/002 Seismic resolution enhancement for tight-sand gas reservoir characterization Seismic amplitude interpretation: 2001 distinguished instructor short course Hilterman 2001 10.1190/1.9781560801993 Lu 2009 Elastic parameters inversion through ray impedance 0016-8033 Geophysics Rutherford 54 1989 10.1190/1.1442696 Amplitude-versus-offset variations in gas sands 0016-8033 Geophysics Santos 69 2004 10.1190/1.1707079 Impedance-type approximations of the P-P elastic reflection coefficients: Modeling and AVO inversion 0016-8033 Geophysics Sava 68 2003 10.1190/1.1581078 Angle-domain common-image gathers by wavefield continuation methods 1742-2132 Journal of Geophysics and Engineering Tang 5 2008 10.1088/1742-2132/5/1/010 PP and PS seismic response from fractured tight gas reservoirs: A case study VerWest 2004 10.3997/2214-4609-pdb.3.P342 Elastic impedance revisited 0016-8033 Geophysics Wang 64 1999 10.1190/1.1444698 Approximations to the Zoeppritz equations and their use in AVO analysis Seismic amplitude inversion in reflection tomography Wang 2003 0016-8033 Geophysics Whitcombe 67 2002 10.1190/1.1451331 Elastic impedance normalization 0016-8033 Geophysics Xu 66 2001 10.1190/1.1487131 Common-angle migration: A strategy for imaging complex media Zhang F. , 2010, Joint inversion of seismic PP- and PS-waves in the ray parameter domain: Ph.D. thesis, Imperial College London.