Reservoir Fluid Identification Method Incorporating Squirt Flow and Frequency-Dependent Azimuthal Anisotropic Inversion

With the continuous development of oil and gas exploration, anisotropic medium has become an important target of oil and gas exploration. Both anisotropy and wave-induced fluid flow have significant influence on fluid identification, but the existing fluid identification methods cannot concurrently consider the impacts of medium anisotropy and wave-induced fluid flow. Therefore, to improve the fluid detection accuracy in anisotropic medium, an anisotropic media solid-liquid decoupling fluid factor with squirt flow effect suitable for the transversely isotropic media with a horizontal symmetry axis (HTI) is constructed based on the theory of rock physics. The fluid sensitivity analysis indicates that the new fluid factor exhibits the highest sensitivity for fluid indication. By introducing the nearly constant Q model to account for viscoelasticity, a reflectivity equation in terms of the new anisotropic media solid-liquid decoupling fluid factor incorporating the squirt flow is derived. Subsequently, a prestack seismic frequency-dependent amplitude variation with angle and azimuth (AVAZ) inversion method is developed. The inversion method takes advantage of the information of offset, azimuth, and frequency contained in seismic data. Synthetic and field examples illustrate the reliability and stability of the proposed prestack seismic frequency-dependent AVAZ inversion method in estimating the new anisotropic media solid-liquid decoupling fluid factor. Our method can serve as a complementary approach to enhance the accuracy of fluid detection in anisotropic reservoirs.