CO2 well construction: lessons learned from US DOE sponsored projects

The objective of a carbon capture and storage (CCS) project is long term storage of CO2 with no migration outside of the storage zone. To meet this objective, CO2 injection wells should meet a higher construction standard than conventional oil and gas wells. Over the last decade multiple injection and monitoring wells have been constructed as part of the United States Department of Energy’s (US DOE’s) regional carbon sequestration partnership and other federally funded programs. These wells provide information and lessons learned that can be applied to future projects as CCS moves from the pilot and demonstration phase to the commercial phase. As part of the US DOE funded Establishing an Early Carbon Dioxide Storage Complex in Kemper County, Mississippi (Project ECO2S) project a study was conducted to collect and compare data from monitoring wells drilled as part of the project and at wells drilled from as part of the Illinois Basin – Decatur Project and the Ohio River Valley CO2 Storage Project / American Electric Power Product Validation Facility Project. The set of wells in this study used a variety of materials and methods for construction. Cements used included common Portland well cement, Portland cement with pozzolan additives to provide CO2 resistance, and highly engineered CO2-resistant cements. Results showed microannuli, cement contamination, and formation breakdown in portions of the wells. Analyses of the operational details of the cementing operations give insight into how these conditions occurred. Each of the wells encountered problems that are common within conventional oil and gas wells. Lessons identified during the study highlight the need to emphasize a successful cement job at every point in the construction of the well from laboratory testing through drilling, cementing, and completion.