Time-lapse Extended Elastic Impedance Application in Estimation of Fluid Saturation and Pressure Changes

Abstract

Some researchers have studied different ways to estimate fluid saturation and pressure changes during production with different 4D seismic attributes. Tura and Lumley (1999) present a method to map and quantify those changes utilizing P- and S-wave impedances. Rojas (2008) proposes to use the P- and S-wave velocities ratio as an indicator of lithologies, fluid saturation, and pressure changes in gas sandstones reservoirs. Landrø (2001, 1999) introduces an elegant, straightforward inversion scheme that solves for pressure and saturation changes from seismic amplitude-variation-with-offset, etc. The advantages of the using of extended elastic impedance to estimate the fluid saturation and pressure are hereafter as: this attribute includes lots of useful pre-stack information related to rock and fluid properties; it can be analyzed with multi-angle to get the best correlation angle for the targeted reservoir parameter; besides, extended elastic impedance improves the stability of elastic impedance, this is good for a more accuracy quantitative estimation of fluid saturation and pressure changes.