Pressure History Matching for CO2 Storage in Saline Reservoirs: Case Study for Citronelle Dome

Carbon Capture and Storage (CCS) projects are subject to monitoring and verification programs to insure the storage is operating safely. Among different verification techniques, Reservoir Simulation and Modeling has proved to be a powerful tool for predicting underground storage behavior and consequently quantifying the risks associated with CO2 storage process.  Reliability of the reservoir simulation models is highly dependent on how accurately simulation results can represent the actual field measurements. This article presents a framework aimed at history matching a reservoir simulation model for a CO2 storage project.

In this study Citronelle Dome which is a saline reservoir located in Mobile County (Alabama, US) is considered for history matching. This project is part of a CO2 storage research plan, conducted by the U.S. Department of Energy (DOE) and some industrial partners to demonstrate viability of commercial-scale storage of CO2 captured from an existing coal-fired power plant.

A Reservoir Simulation model for CO2 injection into the Citronelle saline reservoir was built using a commercially available software application (CMG’s GEM). Field measurements of CO2 injection rates are assigned as the operational constraint to the model. In addition to the Injection rates, high frequency, real-time pressure data from two downhole pressure gauges imbedded in an observation well (250 meters away from the injection well) is also provided. Several uncertain reservoir properties were tuned within reasonable ranges in order to find proper match between simulated pressure results and actual field measurements. Finally, history matched model predicted CO2 plume extension and reservoir pressure up to about 500 years, for monitoring purposes.