Time-lapse AVO inversion: model building and AVA analysis

Abdul-Nassir Saeed, Laurence R. Lines, Gary F. Margrave

Quantitative estimates of the change in reservoir properties can be accomplished by combining rock physics model along with estimated change of P- and Simpedance from time lapse seismic data. The estimated attributes are key steps in discriminating fluid saturation and pressure changes in reservoir. In this report, we have built a time-lapse model for the Pikes Peak area. The elastic physical parameters are carefully selected based on well logs from the survey area. The synthetic P-P and P-S seismic data generated from the model, using CREWES "SYNGRAM", are being tested by proposed time-lapse inverse algorithms being developed. The AVA analysis conducted in this study produces information about rock interfaces only, and aids in calibrating physical parameters used in building of the time-lapse model. The rock modulus attributes LambdaRho () and MuRho () computed from dipole sonic log of the Pikes Peak area help in discriminating lithology, while resistivity and porosity logs give an indication about expected fluid type in the reservoir.