SHALLOW GROUNDWATER MONITORING BEFORE AND AFTER CO2 SEQUESTRATION IN SOUTH CENTRAL KANSAS

A CO₂ injection pilot project is currently being conducted at Wellington Field, Sumner County, south-central Kansas. Injection will be performed in two phases to demonstrate CO₂-Enhanced Oil Recovery (EOR) and permanent carbon storage potential. CO₂-EOR is expected to commence in 2015, within the Mississippian carbonate reservoir. Pending the containment and integrity of CO₂ injected for EOR, injection for permanent storage is expected to commence in 2015, within the deep saline Arbuckle aquifer. Each phase will include approximately 26,000 metric tons of supercritical CO₂ (sCO₂) injected within a period of 8 months.

A pre-injection baseline of chemical and physical parameters has been established to define the hydrogeochemistry of shallow depths on two monitoring wells (100’ and 200’ depths) within the Upper Wellington Formation – a possible Underground Source of Drinking Water (USDW), and will be established for two additional shallow wells. Some important parameters used to establish the baseline for the (100’, 200’) wells are ORP (133.7, 120.5 mV), pH (6.93, 6.65), conductivity (83.9, 68.4 mS/cm, dissolved oxygen (3, 1.5 mg/L), alkalinity (100, 60 mg/L), and chloride (40,000, 100,000 mg/L). These parameters will be measured on the nest of four shallow monitoring wells regularly following injection of both phases to assess if leakage and migration of CO₂ to shallower water sources is occurring, and what effects it has on the possible USDW. A pre-injection baseline will also be conducted on two monitoring wells to assess the Mississippian hydrogeochemistry, and has been conducted on the Arbuckle. Following injections from both phases, water from these wells will be monitored to address the activity of CO₂. An U-tube sampler will be employed to collect in-situ samples from these wells following injection. The samples will be analyzed for tracers, and physical and chemical parameters.