keywords: Cross-plot, lambda-rho, mu-rho, rock-physics, seismic-inversion
Well based feasibility analysis for the sensitivity of rock properties to variation in reservoir properties was carried out to determine the best seismic inversion process to be adopted for the characterization of the undrilled areas of the CHU reservoir in OSI field. Biot Gassmann’s Fluid Substitution Modeling and Castagna Equation were used to estimate shear wave velocity in the absence of acquired shear wave log. Cross plot techniques such as Vp/Vs ratio against P-impedance, Mu-rho against Lambda-rho and Lambda-rho/Mu-rho Vs Lambda-rho were adopted to evaluate the responsiveness of their respective attribute to lithology and fluid discrimination. The Vp/Vs ratio and Lambda-rho attributes gave the best indication of lithology types, while the Lambda-rho attribute demonstrated to be an excellent fluid discriminant. Since the Lambda-rho attribute is a P-wave derived attribute and was sufficient for both lithology and fluid discrimination, P-Impedance inversion will be the best technique for characterization of CHU reservoir in the undrilled area of the studied field.