AN INTEGRATIVE STRATEGY TO INCREASE THE ECONOMIC FEASIBILITY OF CO2 SEQUESTRATION: MINING BRINES FROM SALINE STORAGE RESERVOIRS

One of the critical problems associated with geological CO₂ sequestration is the economic penalty of CO₂ capture and injection. Without a national policy or carbon tax, the economics of sequestration make commercial-scale endeavors extremely difficult. Recent work on a potential sequestration site in southwest Wyoming identified the need for reservoir pressure management during CO₂injection. Formation brine production and treatment was identified as the best pressure management strategy. Brines from the targeted Paleozoic reservoirs have elevated levels of dissolved metals, and could also provide a source of water in an arid region. To address the issue of

economic feasibility of carbon sequestration, the Carbon Management Institute at the University of Wyoming proposes an integrated sequestration strategy of formation fluid production, treatment, and metal and water recovery.

Brines collected from Paleozoic reservoirs through a stratigraphic test well in southwest Wyoming are sodium-chloride-type with total dissolved solids between 75,000 to 95,000 mg/L total. Formation temperatures and pressures

are 92 and 96° C and 4,800 to 5,900 psi, respectively. The brines have increased concentrations of various metals, particularly lithium (90-100 mg/L). The elevated temperature, pressure, and dissolved solids within formation

fluids are ideal for a water treatment scenario that includes geothermal, nano-filtration and reverse osmosis. An integrated engineering solution allows for the optimization of existing reservoir conditions: exploiting the heat and

reservoir pressure of formation fluids for treatment lessens the need for outside power sources and the recovered dissolved metals and treated water can be sold at market values.

An integrated sequestration-brine production strategy offers the potential for offsetting the economic penalty of sequestering commercial quantities of CO₂. The metals and water recovered from co-produced brine could result in substantial economic revenues, and assist in creating a sustainable industry.