Field Testing and Numerical Simulation of Combined CO2 Enhanced Oil Recovery and Storage in the SACROC Unit

Abstract

The SACROC Unit in the Permian Basin has been under carbon dioxide (CO 2 ) injection for enhanced oil recovery (EOR) for almost forty years since CO 2 injection commenced in 1972. The mature CO 2 operations in the SACROC Unit make it an optimal site for studying CO 2 sequestration in conjunction with EOR. A pilot demonstration project was performed in a fivespot pattern, beginning at the end of 2008. The objective of this study is to understand the capacity and flow patterns of the CO 2 plume to determine sequestration potential in conventional oil reservoirs.The pilot site locates in the Northern SACROC platform and was set up as a five-spot pattern consisting of 4 injectors and 1 center producer. Water and CO 2 injection had occurred earlier in the SACROC Unit during reservoir development. The pilot testing started in 2008 and has been under CO 2 injection since then. After thirteen months of CO 2 injection, the production data from the pilot showed that the oil production rate of the producer (well 56-17) increased over tenfold during the first year of CO 2 injection which demonstrated significant enhanced oil recovery by CO 2 injection. This paper describes how the injection process in the SACROC pilot was simulated using a compositional simulator, Computer Modeling Group's GEM. A simulation model with 47,104 grids was developed with geophysical data characterized from 3D seismic surveys and well logs. The simulation area is 6640 ft * 6640 ft * 840 ft, consisting of five wells in the pilot site. History matching gas, oil, and water production for each well since first drilled was performed to verify the model. The EOR under three injection schemes was predicted. The CO 2 storage capacity under residual and solubility trapping mechanisms during CO 2 miscible displacement was simulated and analyzed. This study demonstrated CO 2 sequestration in oil reservoirs to be a low-risk, promising method for mitigating CO 2 discharge into the atmosphere. Relative permeabilityPreviously reported laboratory results (Brummett, 1976) verified residual oil saturation by water displacement of 26.1%. Experimental work performed by the Anderson et al. (Anderson et al., 1954) established an average irreducible water saturation of 17.7%. These values were used as the endpoints of the water-oil relative permeability relationship. The water/oil relative permeability curves used in this work are shown in Figure 7. Simulation results discussionThe reservoir performance under stimulation and CO 2 migration status was simulated by a compositional simulator, CMG's GEM. The fluid properties were tuned by PVTsim and CMG's Winprop. History matchThe history match was accomplished with two main constraints: one specifies oil rate SC (surface rate) production and matches the gas production and water production, the other specifies gas rate SC (surface rate) and matches the oil production Several simulations have been performed for the SACROC northern platform. Early simulation used an artificial model or and water production.

CO2 retention values in enhanced oil recovery

“…Hence, results are not representative neither of the performance the field would have had if the CO 2 -EOR would be started today nor meaningful for the extrapolation to reservoirs with similar characteristics. Under such circumstances, a recent pilot test using a 5-spot pattern is regarded as providing more representative statistics (Xiao et al, 2011). Lost Soldier, the last unit listed in Table 1, started its CO 2 -EOR in 1989 (Brokmeyer et al, 1996;Wo, 2007).…”

Carbon Capture, Utilization, and Storage in Saline Aquifers: Subsurface Policies, Development Plans, Well Control Strategies and Optimization Approaches—A Review

“…Other researchers have investigated the co-optimization problem of CO 2 -EOR and CO 2 storage, i.e., CO 2 -EOR+ reporting various development strategies/plans that affect oil production, carbon storage, and other effects without considering a specific objective function [110][111][112][113][114][115][116][117][118][119][120][121][122]. Meanwhile, in the absence of a direct relationship on how to achieve the technical strategy of co-optimizing CO 2 EOR and carbon storage in practice, a second group approached this difficulty by explicitly considering maximizing oil recovery, carbon storage, or a weighted combination of the two objectives using injection strategy techniques [123][124][125][126][127][128][129][130].…”

Gas injection may have triggered earthquakes in the Cogdell oil field, Texas

“…Detailed modeling investigations (21,24) of hydrology and subsurface stress, comparing subsurface conditions in the Cogdell, Kelly-Snyder, and Salt Creek fields, might provide answers to this question. There have been preliminary monitoring and modeling of the consequences of SCCO 2 injection in the Kelly-Snyder (SACROC) unit (25,26). The presence of detectable seismic activity in the Cogdell field and its absence in the apparently similar Kelly-Snyder and Salt Creek fields makes these fields attractive candidates for detailed geomechanical modeling, as has been recently applied to CO 2 injection sites near the coast of Italy (27).…”