Impact of joint PP/PS inversion on shear-impedance estimation for exploration and production

Abstract

Joint pre-stack inversion of PP- and PS-wave data is shown to significantly improve estimation of in particular S-impedance but also P-impedance and density. For reservoir characterization, improvements in these parameters can better identify reservoir rock and fluid properties. For reservoir monitoring, time-lapse changes in P-impedance, S-impedance and density can lead to more accurate inversion of saturation and pressure changes. These claims are first demonstrated on synthetic data, and later the value is shown on onshore and offshore field projects. Joint inversion of PP- and PS-wave data requires a higher level of care compared to PP-waves alone since the two wave-modes need to be acquired, processed and merged properly. This has diminished the use of PS-waves in the past. However, modern acquisition and processing on land and offshore data make this technology quantitatively more accurate and realizable. It is shown that joint inversion can lead to a larger chance of success in placing exploration and development wells.