Hydrocarbon identification by evaluating anisotropy parameters estimated from crosswell seismic data

Abstract

This study aims to identify hydrocarbon by evaluating anisotropy parameters estimated from corsswell seismic data. Several approaches were performed in this study included shear wave splitting (SWS) and angle-based velocity variation (VVA) methods. Anisotropy coefficient K was estimated by SWS method and anisotropy parameters ε, δ, and γ were estimated using modified Thomsen’s equations in Vertically Transverse Isotropy (VTI) medium applied to Crosswell seismic geometry. The velocity variation was observed when pressure (P) wave propagated through a layered media containing hydrocarbon. The P-wave velocity was decreasing along with the increasing of the incidence angle and the calculated values of anisotropy (ε, δ, γ, and K) on the target zone within interval 1390 m to 1820 m depth were relatively high compared to the zone does not contain hydrocarbon. The evaluation was verified with Poisson’s, pressure wave velocity (VP) and shear wave velocity (VS) ratio analyses and validated to the existing petrophysics data. In conclusion, anisotropy values (ε, δ, γ and K) and velocity variation with angle of incidence have a positive relationship with hydrocarbon and applicable as a tool for identifying the presence of hydrocarbon in layered media.