Saturated Fluid Variation Effect on Seismic Anisotropy: A Case Study of Deep-Water Reservoir

Abstract

Many factors can drive seismic anisotropy, whether it is the intrinsic condition of rock, external force, or longwave anisotropy. Saturated fluid, as one of the reservoir’s intrinsic elements, is known to trigger an anisotropic effect in far offset seismic with Vertical Transverse Isotropic character. Anisotropy on seismic presents as hockey stick curving that a combination of two-parameter could correct during move-out: V NMO and the elliptical anisotropy η parameter. This research means observing how the saturated fluid within the reservoir contributes to the observed anisotropy in seismic. Rock physics modelling (RPM) and fluid substitution (FRM) are conducted to investigate the saturated fluid effect at a particular temperature and pressure that reflects the deep-water environment. The anisotropy parameter is extracted by applying Tsvankin 4th Order NMO to obtain the elliptical anisotropy η parameter. Based on synthetic seismic modelling with VTI Rüger Reflectivity, saturated fluid has an effect on far offset seismic as a manifestation of seismic anisotropy η. In this case of a deep-water environment, gas saturated sand needs the most considerable η correction, followed by oil and water-saturated. Although the η value difference is relatively small and easily dismissed as insignificant, saturated fluid indeed does contribute to the observed seismic anisotropy.