Demonstration Numerical Simulation of Field-Scale CO2 Sequestration Project with Complex Faulting System in San Juan Basin, USA

Abstract

Abstract San Juan Basin (SJB) is a geologic structural basin located in northwest New Mexico. Comprehensive field-scale reservoir simulation work was performed in finely constructed basin-wide geologic models, targeting sequestering over 120 million metric tons of CO2 for a period of 20 years. Petrophysical properties were populated through well logs and measurements on core samples obtained from nearby wells within the study area. Various critical storage trapping mechanisms were considered. The threshold pressure in delineating AoR is formulated based on guidance provided by the Environmental Protection Agency (EPA) to ensure the safety of underground drinking water sources (USDW). Besides, a complex faulting system identified on the west side of the basin was modeled to preclude risks of CO2 migration. The faulting system at the northwestern SJB was identified through well log stratigraphy. A near-vertical faulting system was mapped that may pose uncertainties to the sealing capacities of the caprock layer. The preliminary structural map shows a relatively flat topography that deepens to the east; and a high area in the west-northwest that is produced by faulting within a Hogback Monocline. The relief on the fault/monocline averages around 4,000 to 4,500 feet. Our simulation results indicate that SJB has the potential to safely contain the proposed amount of CO2 and avoid the impact of faulting systems. Further, pressure build-up in the injection zone is the most influential factor that may endanger the drinking water aquifer through the active injection and post-injection site care phases compared to CO2 plume migration. Controlling the size of AoR will increase the overall storage capacity within the area of interest while cutting down the overhead for corrective action planning and site monitoring. This work employed realistic reservoir characterization data from San Juan Basin CarbonSAFE Phase III project to construct the reservoir simulation model, including 3D seismic, well logs, core analysis, and fluid sampling. As the worldwide commercial CO2 geologic storage projects aiming for soaring storage capacity goals, the processes in this work demonstrated the workflow to manage a large-scale CO2sequestration project in complex geological structured reservoirs.