INTERPRETING AZIMUTHAL FOURIER COEFFICIENTS FOR ANISOTROPIC AND FRACTURE PARAMETERS

Amplitude versus Offset and Azimuth (AVOAz) Analysis can be separated into two separate parts; Amplitude versus Offset (AVO) analysis and Amplitude versus Azimuth (AVAz) analysis. Useful information about fractures and the anisotropy is obtained by just examining the AVAz. The AVAz can be described as a sum of sinusoids of different periodicities, each characterized by its magnitude and phase. This sum is mathematically equivalent to a Fourier series and hence the coefficients describing the AVAz response are azimuthal Fourier coefficients (azimuthal FCs). This FC parameterization is purely descriptive. The aim of this paper is to help the interpreter understand what these coefficients mean in terms of anisotropic and fracture parameters for the case of P-wave reflectivity using a linearized approximation.