Fracture characterization using converted waves

Abstract

A B S T R A C TWe present a method for inversion of fracture compliance matrix components from wide-azimuth noisy synthetic PS reflection data and quantitatively show that reflection amplitude variations with offset and azimuth for converted PS-waves are more informative than P-waves for fracture characterization. We consider monoclinic symmetry for fractured reservoir (parameters chosen from Woodford Shale), which can be formed by two or more sets of vertical fractures embedded in a vertically transverse isotropic background. Components of effective fracture compliance matrices for a medium with monoclinic symmetry are related to the characteristics of the fractured medium. Monte Carlo simulation results show that inversion of PS reflection data is more robust than that of PP reflection data to uncertainties in our a priori knowledge (vertically transverse isotropic parameters of unfractured rock) than PP reflection data. We also show that, while inversion of PP reflections is sensitive to contrasts in elastic properties of upper and lower media, inversion of PS reflections is robust with respect to such contrasts.

Joint PP‐ and PSV‐wave amplitudes versus offset and azimuth inversion for fracture compliances in horizontal transversely isotropic media

“…Behura and Tsvankin (2006) presented small-angle AVO response of PS waves in tilted transversely isotropic media. Far and Hardage (2015) implemented fracture compliance matrix components estimation from synthetic PS-wave data, which reveal that reflection AVOA for converted PS waves is more informative than P waves for fracture characterisation. Far and Hardage (2015) implemented fracture compliance matrix components estimation from synthetic PS-wave data, which reveal that reflection AVOA for converted PS waves is more informative than P waves for fracture characterisation.…”

“…Much work has been done to utilise PSV-wave data to detect fractures (Li 1998;Grechka, Theophanisz and Tsvankin 1999;Tsvankin and Larner 2004;Tang, Zhang and Li 2008;. Far and Hardage (2015) implemented fracture compliance matrix components estimation from synthetic PS-wave data, which reveal that reflection AVOA for converted PS waves is more informative than P waves for fracture characterisation. This allows us to attempt to implement joint PP-and PSV-wave amplitude inversions to improve the accuracy of the estimation of the unknown parameter (i.e., Lamé impedances, density, and fracture compliances).…”