Improvement and Sensitivity of Reservoir Characterization Derived From Time-Lapse Seismic Data

Abstract

Abstract In general only a single 3D seismic data set is used for the characterization of the static properties of a reservoir, even though these static properties could be integrated with dynamic properties. But sometimes, more than one 3D seismic data volume has been acquired over the same field after the production starts. We propose to use these additional data not only to understand the dynamic properties of the reservoir using a time-lapse seismic analysis as presented last year, but to improve the accuracy of the initial reservoir description and study its sensitivity to the input data during the optimization process. Using two 3D seismic data sets acquired over a field in the Gulf of Mexico, this paper demonstrates a method to improve the porosity map obtained from the geostatistical characterization of the base 3D seismic data set by an analysis of the second 3D data volume. It is not possible using just the base data to differentiate factors such as fluid content and pressure from the geostatistical porosity characterization. But by using the flow information from the wells and the second 3D seismic data which was acquired after the production started, it is possible to decouple the porosity, fluid contents and even pressure. Consequently, it provides a more representative porosity characterization compared to using a single 3D seismic data set. The relative permeability curves are optimized by comparing actual time-lapse seismic and production data to synthetic ones generated with a Gassmann rock physics model. P. 527