Seismic Signal and Data Analysis of Rock Media with Vertical Anisotropy

Abstract

This paper is concerned with anisotropic effects on seismic data and signal analysis for transversely isotropic rock media with vertical anisotropy. It is understood that these effects are significant in many practical applications, e.g. earthquake forecasting, materials exploration inside the Earth's crust, as well as various practical works in oil industry. Under the framework of the most accepted anisotropic media model (i.e. VTI media, transverse isotropy with a vertical axis symmetry), with applications of a set of available anisotropic rock parameters for sandstone and shale, we have performed numerical calculations of the anisotropic effects. We show that for rocks with strong anisotropy, the induced relative depth error can be significantly large. Nevertheless, with an improved understanding of the seismic-signal propagation and proper data processing, the error can be reduced, which in turn may enhance the probability of forecasting accurately the various wave propagations inside the Earth's crust, e.g. correctly forecasting the incoming earthquakes from the center of the Earth.

Acoustic Waves at the Interface Between Different Types of Anisotropic-Strata

“…Now, consider an incident P-wave from VTI to TTI medium with an incident angle (θ). For the TTI medium, Bond transformation can be used to convert its tilt-angle structure to the same tensor form of the VTI structure [24][25][26][27][28][29][30][31][32][33][34]; Kelvin-Christoffel equation can be solved for the reflected and refracted coefficients;…”

“…While an interface between likewise-media has a relatively simple geometric structure [24][25][26][27][28][29][30][31][32][33][34], the interface between unlike-media can be much more complicated [35].…”

Research Progress in Acoustical Application to Petroleum Logging and Seismic Exploration

“…Ostrander [17] showed that AVO anomalies can indicate areas of Poisson's ratio change and are direct hydrocarbon indicators. However, anisotropy has potentially significant effects on AVO application and time-depth conversion of seismic data [18,19]. It is well known that elastic anisotropy is so common in Earth's interior that it is virtually impossible to avoid it in geophysical studies.…”

Anomalous Refraction of Transversely Isotropic Media with Strong Anisotropy

“…Reflection and refraction of acoustic waves between adjacent rocks have profound implications in geophysics, e.g., in earthquake seismology, seismic image and analysis, and underwater acoustics [5][6][7][8][9][10][11]. The physical properties of the transversely isotropic media with a vertical axis of symmetry (VTI media), as shown in Figure 1(a), can be described by an elastic stiffness tensor [2,7,[12][13][14][15][16]…”