Study on the Transport and Transformation Law of CO₂ Marine Storage in Reservoirs with Various Permeability Anisotropy

There is an international consensus to reduce the pace of global warming caused by greenhouse gases, such as CO₂.The geological storage of CO₂ plays a crucial role in reducing the atmospheric CO₂ concentration, and hydrate-based CO₂ storage is an important geological storage technology applied to seabed sediments, which has attracted increasing attention due to its advantages of high safety and large storage capacity. In this study, a large-scale numerical simulator applicable to CO₂ hydrate storage is developed, which considers the two-phase flow process including hydrate formation and realizes the coupling of the thermal-fluidic-chemical three fields, and further investigates the transport and transformation behavior of CO₂ in the reservoir with anisotropic permeability during the injection period and at the cessation of injection. The results show that the formation of CO₂ hydrate can easily generate local high-pressure zones and local high-temperature zones inside the reservoir; the CO₂ hydrate cap formed above the wellhead can limit the vertical transport distance of CO₂ and ensure the safe storage of CO₂. In addition, this study also analyzed the efficiency of CO₂ hydrate storage in different permeability anisotropic reservoirs and found that high Khv reservoirs are more conducive to CO₂ conversion in the long term. This study can provide scientific value for the hydrate-based CO₂ storage in the ocean and a theoretical basis for the transport behavior of CO₂ in submarine reservoirs.