fluidsubstitution.ppt

Contents Benefits Introduction Gassmann Equation in Shaley Formation Wyllie Time Series Equation Linking Gassmann to Wyllie Adding a gas term to Wyllie Equation Krief Equation Examples Conclusions Benefits – Seismic Reliable compressional and shear curves even if no acoustic data exists. Quantify velocity slowing due to presence of gas. Full spectrum of fluid substitution analysis. Reliable mechanical properties, Vp/Vs ratios. Reliable synthetics. Does not involve neural network or empirical correlations. Benefits – Petrophysics Verifies consistency of petrophysical model. Ability to create reconstructed porosity logs using deterministic approaches. Benefits – Engineering Reliable mechanical property profiles for drilling and stimulation design. Does not rely on empirical correlations, or neural network curve generation, for mechanical properties. Introduction A critical link between petrophysics and seismic interpretation is the influence of fluid content on acoustic and density properties. Presented are two techniques which rigorously solve compressional and shear acoustic responses in the entire range of rock types, and assuming different fluid contents. Gassmann Equation inShaley Formation – I The Gassmann equation accounts for the slowing of acoustic compressional energy in the formation in the presence of gas. There is no standard petrophysical analysis that accounts for the Gassmann response and incorporates the effect in acoustic equations (e.g. Wyllie Time-Series). Terms in the Gassmann equation: Gassmann Equation inShaley Formation – II In shaley formation, adjustments need to be made to several of the Gassmann equation terms, including porosity and bulk modulus of the solid components. This allows a rigorous solution to Gassmann through the full range of shaley formations. Estimates of shear acoustic response are made using a Krief model analogy. Wyllie Time Series Equation In the approach presented here, we have solved the Gassmann equation in petroph