none 10.1190/geo2011-0028.1 Society of Exploration Geophysicists Society of Exploration Geophysicists 186 53074998 5981 2025121114082924800 10.1190 2025-12-11T19:08:32Z 2011-12-31T18:01:51Z 17 Geophysics 1942-2156 0016-8033 01 18 2012 11 1 2011 11 01 2011 76 6 Davide Gei Istituto Nazionale di Oceanografia e di Geofisica Sperimentale (OGS), and University of Trieste, Department of Geosciences, 1 Trieste, . E-mail: dgei@ogs.trieste.it . Italy Leo Eisner Czech Academy of Sciences 2 , Institute of Rock Structure and Mechanics, Prague, . E-mail: leo@irsm.cas.cz . Czech Republic Peter Suhadolc University of Trieste 3 , Department of Geosciences, Trieste, . E-mail: suhadolc@units.it . Italy ABSTRACT Microseismic data recorded by surface monitoring arrays can be used to estimate the effective anisotropy of the overburden and reservoir. In this study we used the inversion of picked P-wave arrival times to estimate the Thomsen parameter δ and the anellipticity coefficient η. This inversion employs an analytic equation of P-wave traveltimes as a function of offset in homogeneous, transversely isotropic media with a vertical axis of symmetry. We considered a star-like distribution of receivers and, for this geometry, we analyzed the sensitivity of the inversion method to picking noise and to uncertainties in the P-wave vertical velocity and source depth. Long offsets, as well as a high number of receivers per line, improve the estimation of δ and η from noisy arrival times. However, if we do not use the correct value of the P-wave vertical velocity or source depth, the long-offset may increase the inaccuracy in the estimation of the anisotropic parameters. Such inaccuracy cannot be detected from time residuals. We also applied this inversion to field data acquired during the hydraulic fracturing of a gas shale reservoir and compared the results with the anisotropic parameters estimated from synthetic arrival times computed for an isotropic layered medium. The effective anisotropy from the inversion of the field data cannot be explained by layering only and is partially due to the intrinsic anisotropy of the reservoir and/or overburden. This study emphasizes the importance of using accurate values of the vertical velocity and source depth in the P-wave arrival time inversion for estimating anisotropic parameters from passive seismic data. 01 18 2012 11 1 2011 11 01 2011 12 30 2011 WC117 WC126 10.1190/geo2011-0028.1 https://pubs.geoscienceworld.org/geophysics/article/76/6/WC117/285912/Feasibility-of-estimating-vertical-transverse https://pubs.geoscienceworld.org/seg/geophysics/article-pdf/76/6/WC117/3225799/geo2011-0028.pdf https://pubs.geoscienceworld.org/seg/geophysics/article-pdf/76/6/WC117/3225799/geo2011-0028.pdf http://geophysics.geoscienceworld.org/cgi/doi/10.1190/geo2011-0028.1 0016-8033 Geophysics Alkhalifah 59 1994 10.1190/1.1443698 Migration error in transversely isotropic media 0016-8033 Geophysics Alkhalifah 60 1995 10.1190/1.1443888 Velocity analysis for transversely isotropic media 1070-485X The Leading Edge Alkhalifah 15 1996 10.1190/1.1437345 Velocity analysis and imaging in transversely isotropic media: Methodology and a case study 0148-0227 Journal of Geophysical Research Backus 67 1962 10.1029/JZ067i011p04427 Long-wave elastic anisotropy produced by horizontal layering 0016-8033 Geophysics Banik 49 1984 10.1190/1.1441770 Velocity anisotropy of shales and depth estimation in the North Sea Basin 0016-8025 Geophysical Prospecting Bulant 55 2007 10.1111/gpr.2007.55.issue-6 Importance of borehole deviation surveys for monitoring of hydraulic fracturing treatments Wave fields in real media: Theory and numerical simulation of wave propagation in anisotropic, anelastic, porous and electromagnetic media Carcione 2007 1070-485X The Leading Edge Chambers 29 2010 10.1190/1.3353725 Investigation of induced microseismicity at Valhall using the life of field seismic array 0016-8025 Geophysical Prospecting Chambers 58 2010 10.1111/j.1365-2478.2010.00893.x Testing the ability of surface arrays to monitor microseismic activity 1070-485X The Leading Edge Eisner 30 2011 10.1190/1.3609092 Effective VTI anisotropy for consistent monitoring of microseismic events Fomel 1997 On nonhyperbolic reflection moveout in anisotropic media 0016-8025 Geophysical Prospecting Grechka 50 2002 10.1046/j.1365-2478.2002.00307.x P-wave stackingvelocity tomography for VTI media 0016-8033 Geophysics Grechka 63 1998 10.1190/1.1444407 Feasibility of nonhyperbolic moveout inversion in transversely isotropic media 0956-540X Geophysical Journal International Jech 108 1992 10.1111/gji.1992.108.issue-2 Kinematic inversion for qP- and qS-waves in inhomogeneous hexagonally symmetric structures Lynn 1991 10.1190/1.1888724 Where are the fault-plane reflections? 0016-8025 Geophysical Prospecting Sarkar 54 2006 10.1111/j.1365-2478.2006.00556.x Anisotropic migration velocity analysis: Application to a data set from West Africa 0016-8033 Geophysics Thomsen 51 1986 10.1190/1.1442051 Weak elastic anisotropy 0016-8033 Geophysics Tsvankin 60 1995 10.1190/1.1443755 Normal moveout from dipping reflectors in anisotropic media 0016-8033 Geophysics Tsvankin 59 1994 10.1190/1.1443686 Nonhyperbolic reflection moveout in anisotropic media 0016-8033 Geophysics Tsvankin 60 1995 10.1190/1.1443838 Inversion of reflection traveltimes for transverse isotropy 0956-540X Geophysical Journal International Verdon 179 2009 10.1111/gji.2009.179.issue-2 Imaging fractures and sedimentary fabrics using shear wave splitting measurements made on passive seismic data