| Popis: |
An improved understanding of flow behavior in older producing reservoirs, plus proactive reservoir management measures could lead to improving recovery efficiency. In this regard, one such measure is the use of time-lapse, multi-component seismic imaging to enhance the characterization of the reservoir's flow model. In this paper, we describe the application of this concept to a CO2 EOR project in Morrow sandstone in Postle field, Oklahoma, USA. Production and injection in the Morrow sandstone will cause saturation changes and can influence reservoir pressure based on operating practices. These changes, in turn, affect acoustic and elastic properties of rocks, which are detectable by time-lapse seismic imaging. Coupling these changes into flow simulation improves our understanding of the reservoir heterogeneity and connectivity. A reservoir simulation model was initially built using available geological, petrophysical and engineering data. The fluid flow performance was compared against observed reservoir performance. Time-lapse seismic anomalies, which are indicative of permeability variation in the reservoir, have been used to better understand reservoir connectivity and improve the quality of the reservoir model. On the other hand, flow simulation results help geophysicists to better interpret the time-lapse seismic anomalies. Results indicate that time-lapse seismic is capable of inferring the permeability field and can detect stratigraphic baffles in the reservoir. Additionally, it provides valuable inter-well information that can assist the history matching process and improve the quality of the reservoir model results. We also found out that although it is normally expected that the P-wave seismic anomalies show mainly the changes due to fluid saturation, our interpretation based on production / injection data and simulation study indicates that pressure changes can also affect the P-wave anomalies. Our research results demonstrate that dynamic reservoir characterization and integration of flow simulation and 4D seismic is a viable method for building an integrated reservoir model that can be used to guide field operations and maximize recovery efficiency. |
