Propagation characteristics of converted refracted wave and its application in static correction of converted wave

Abstract

Three-component seismic exploration through P-wave source and three-component geophone is an effective technique used in complicated reservoir exploration. In three-component seismic exploration data processing, one of the difficulties is static correction of converted wave. This paper analyzes propagation characteristics of non-converted and converted refracted waves, and discovers a favorable condition for the formation of converted refracted wave, i.e. the velocity of overlaying medium S wave is much lower than that of underlying medium S wave. In addition, the paper proposes the static correction method of converted wave based on PPS converted refracted wave, and processes the real three-component seismic data with better results of static correction of converted wave. PPS converted refracted wave, converted wave, static correctionThe recent seismic exploration technology of P-wave source generating seismic wave and three-component geophone receiving P wave (P-P wave) and converted wave (P-S wave) is the most efficient method in complicated reservoir prospecting [1][2][3][4] . Considering the low and rapidly changed velocity of near-surface S wave, how to eliminate the influence of near-surface S wave on reflected S-wave propagation time (S-wave static correction) is especially important [5] .There have been three static correction methods of converted wave: (a) the calculation of S-wave static correction value from inversion of S-wave velocity based on Love wave dispersion [6] , (b) the inversion of near-surface S-wave velocity by the non-converted refracted S wave [7] , and (c) the direct derivation of the maximum stack power of S-wave static correction [5] . Since the widely used P-wave seismic source in seismic survey makes it difficult to observe Love wave and nonconverted refracted S wave, the application of the first two methods has limitations. The third method cannot fundamentally solve the problem of long wave-length S-wave static correction for its approximation to residual static correction.In 2002, Ritzwoller and Levshin [8] proposed the use of surface wave dispersion and non-converted refracted P and S waves in the inversion of surface S-wave velocity. Li [9] suggested the adoption of first break travel-time difference of Z and X component seismic record to calculate S-wave static correction value. Heelan [10] studied how to calculate amplitude intensity of refracted wave. Hall [11] explained non-converted and converted refracted waves, and briefly described the propagation kinematics characters. Most studies in recent decades on refracted wave have focused on non-converted refracted wave (PPP and SSS refracted wave) [12][13][14][15][16][17] , with little work on

Converted‐Wave Static Correction Method for Thick Weathering Area

“…Generally speaking, S-wave statics is far greater than Pwave's, the relevance of them is very small. According to Hall's description of kinematical feature of the converted-refraction and non convertedrefraction [15] and Liu's quantitative analysis for PPS converted-refraction [20] , P-wave refraction will be converted to S-wave at the bottom of weathering (that is Fig. 1 The geometry relationship of upgoing P-and S-wave travel in the near surface top of HVL) due to strong S-wave velocity contrast, the majority energy will be recorded by horizontal component (Fig.…”

“…Most of recent literatures are involved in non converted-refraction (PPP and SSS mode) [16−19] , and converted-refraction is rarely mentioned. Liu [20] gave an overall analysis for converted-refraction's propagation law and characterization, he pointed out that the favorable condition for generating converted-refraction is that the upper layer velocity is far less than lower layer's, he derived S-wave delay-time from converted-refraction and then S-wave statics are obtained. This paper gives a detailed derivation for accurate S-wave statics utilizing the PPP and PPS mode refraction, involved velocity ratios are only regional values which constrain the calculation.…”

Propagation of S-waves in a non-homogeneous anisotropic incompressible and initially stressed medium

“…Addy et al (2005) have studied Rayleigh waves in a viscoelastic half-space under initial hydrostatic stress in presence of the temperature field. Liu et al (2008) have demonstrated the propagation characteristics of converted refracted wave and its application in static correction of converted wave. Moczo et al (2007) provided mathematical modeling of seismic wave propagation using the Finite-Difference time-domain method.…”

Resolution enhancement in shallow 3D-PS seismic reflection

“…This cannot be guaranteed. Arguably more justifiable are approaches which analyse horizon-timing differences on common-receiver-gathers (CRGs) (Cary and Eaton, 1993), or methods using PPS and SSS refractions (Houston et al, 1989;Liu and Wei, 2008). More recent areas of study include a technique based on correlation of adjacent CRGs (Guevara et al, 2015); ray-path interferometry via the radial trace or Tau-p domains (e.g.…”