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

Abstract

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 K_hv 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.