CO2 Plume Tracking and Monitoring at Wellington Field CO2 EOR Pilot

Abstract

Approximately 20,000 metric tons of CO2 were injected in the upper part of the Mississippian dolostone reservoir to verify CO2 EOR viability in carbonate reservoirs and evaluate a potential of transitioning to geologic CO2 storage through EOR. Total of 1,101 truckloads, average of 120 tonnes per day were delivered over the course of injection that lasted from January 9 to June 21, 2016.

Geochemical water analysis of organic and inorganic components was performed in order to understand if this method could be used as an early CO2 detection system, as a plume location and containment method, and in order to understand a degree of impact of CO2 on mineral composition, detect changes in water and rock geochemistry as a result of injection. Along with geochemical survey, pressure and production data was recorded at wells and tank batteries.

Based on reservoir simulations, wells surrounding CO2 injector were grouped in three areas: two inner circles with the radiuses of 182 m and 460 m. Wells within this radius were sampled weekly during the course of CO2 injection, since January 9, 2016. Wells within third radius of 1 km around KGS 2-32 were sampled after initial break-through at the wells of the first inner circle; however, sampling interval for these wells was chosen according to flood performance and was not strictly set from the beginning of the injection. In total, analysis of 17 wells surrounding injector well was performed. Additional geochemical sampling was performed by contracting Baker and Hughes Oilfield Services that conducted monthly since the start of injection and continued until September, 2017.

Total dissolved solids and pH measurements were analyzed in the field and alkalinity analysis was performed in the lab shortly after sample arrival. These results were used as an early detection for CO2 arrival at well locations. On average, wells started to produce CO2 approximately 2-3 weeks after initial increase in alkalinity. However, some wells did observe alkalinity increase without free gas production. Collected data cation, anion, and organic components data is being currently analyzed and finalized results and findings will be published at a later date.

AAPG Datapages/Search and Discovery Article #90323 ©2018 AAPG Annual Convention and Exhibition, Salt Lake City, Utah, May 20-23, 2018