Study on the Transport and Transformation Law of CO<sub>2</sub> 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 CO<sub>2</sub>.The geological storage of CO<sub>2</sub> plays a crucial role in reducing the atmospheric CO<sub>2</sub> concentration, and hydrate-based CO<sub>2</sub> 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 CO<sub>2</sub> 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 CO<sub>2</sub> in the reservoir with anisotropic permeability during the injection period and at the cessation of injection. The results show that the formation of CO<sub>2</sub> hydrate can easily generate local high-pressure zones and local high-temperature zones inside the reservoir; the CO<sub>2</sub> hydrate cap formed above the wellhead can limit the vertical transport distance of CO<sub>2</sub> and ensure the safe storage of CO<sub>2</sub>. In addition, this study also analyzed the efficiency of CO<sub>2</sub> hydrate storage in different permeability anisotropic reservoirs and found that high <I>K</I><sub>hv</sub> reservoirs are more conducive to CO<sub>2</sub> conversion in the long term. This study can provide scientific value for the hydrate-based CO<sub>2</sub> storage in the ocean and a theoretical basis for the transport behavior of CO<sub>2</sub> in submarine reservoirs.