WaterRF Project: Research Approach

Objectives

Assess impacts of CO₂ leakage on groundwater quality using field studies based on push-pull tests in a shallow aquifer at a geological carbon sequestration site in the Gulf Coast;
conduct laboratory batch experiments to determine impacts of CO₂ on major and trace elements;
simulate test results to assess processes, including impacts of CO₂ on major and trace elements;
evaluate which geochemical parameters are most diagnostic of CO₂ leakage into USDWs; and
interact with utilities and regulators to communicate results of this study and to provide input to regulations.

Methods
Impacts of CO₂ leakage on groundwater quality will be evaluated using single-well push-pull tests (PPTs) (Figure 4) in a sedimentary aquifer on the Gulf Coast. These controlled field tests allow isolation of impacts of CO₂ leakage into an aquifer without the confounding issues associated with upward migration of brines with CO₂ that can occur when natural systems (e.g. Keating et al., 2009) are evaluated. Methods are generally subdivided into the following tasks.

Figure 4. Schematic of push-pull tests, including an injection phase in which CO₂ and a conservative tracer are injected into the aquifer, a resting period for reactions to take place, and a pull phase in which groundwater is pumped out of the system.

The following provides background information and the tasks.