Managing Chemistry Underground: Is Co-Sequestration an Option in Selected Formations?

Abstract: Geochemical simulations indicate that co-injection of CO₂ and SO₂ results in mineral sequestration of SO₂. The amounts sequestered are greater and more persistent in dolomite and basalt than in glauconitic sandstone. In a predominantly dolomite formation, dissolution of calcite, and to a lesser extent, dolomite, will provide Ca in solution to promote the precipitation of anhydrite, thus removing the SO₂ from solution. In basalt, dissolution of basaltic glass under acidic conditions provides Ca and Fe in solution, which promotes the sequestration of SO₂ as anhydrite and, eventually, pyrite. As magnetite in the formation is consumed, pyrite redissolves. In the basalt, 86% to 47% of the SO₂ remains sequestered after 5000 years. In glauconitic sandstone, SO₂ precipitates as alunite, but it eventually redissolves. After 5000 years, 87% to 0% of the SO₂ remains sequestered in the glauconitic sandstone. In all cases, co-injection of 1% SO₂ with CO₂ did not appreciably reduce the amount of CO₂ sequestered, and did not induce a measureable change in porosity versus injection of CO₂ alone. [Copyright &y& Elsevier]