EXPERIMENTAL EVALUATION OF IN-SITU CO2-WATER-ROCK INTERACTION DURING CO2 INJECTIONS IN BASALTIC ROCKS: IMPLICATIONS FOR CO2 SEQUESTRATION

Carbon dioxide (CO2) emissions have increased with industrialization in the last century. Coal-fired power plants are among the largest point sources of CO2 emissions. There is growing concern these emissions are contributing to global warming. One approach being explored is geologic sequestration, which is the injection of CO2 into subsurface reservoirs where there is sufficient permeability, depth, and confinement to allow safe injection of large volumes of CO2. Depleted oil and gas fields, unmineable coal beds, organic-rich shales, and saline water-bearing formations have all been identified as potential repositories for CO2. Flood basalts are a potentially important host medium for geologic sequestration of anthropogenic CO2. Most lava flows have flow tops that are porous and permeable and have enormous capacity for storage of CO2. Interbedded sediment layers and dense low-permeability basalt rock overlying sequential flows may act as effective seals allowing time for mineralization reactions to occur. Laboratory experiments being conducted at Lamont-Doherty Earth Observatory with Palisade Diabases confirm relatively rapid chemical reaction of CO2-saturated pore water with basalts to form stable carbonate minerals. Calculations suggest a sufficiently short time frame for onset of carbonate precipitation after CO2 injection that verification of in situ mineralization rates appears feasible in field pilot studies. If proven viable, major flood basalts in the United States and India would provide significant additional CO2 storage capacity and additional geologic sequestration options in certain regions where more conventional storage options are limited.