Insights into conjugate heat transfer and methane dissolution in underground salt caverns

CFD modeling has been performed of the natural convection flow patterns, heat transfer, and methane dissolution that develop in gas storage cavities which are formed in rock salt geology by controlled pumping of water to dissolve the salt, leaving a cavern into which methane is then injected to displace the brine. URANS simulations are reported of the brine flow, together with conjugate heat transfer in the surrounding rock, and the methane concentration as it is dissolved into the brine. Results demonstrate that such an approach can be used to reproduce the rather complex flow development. When the cavity is nearly full of brine a steady stratified layer develops at the top of the brine, which inhibits mixing. As the cavity is emptied, this layer can become disturbed, leading to higher mixing and methane dissolution rates across it.