Development of new CO2 heating process for offshore geological storage

Detailed analyses must be carried out to ensure that CO2 is transmitted and injected economically in offshore geological storage facilities. It is crucial to analyze not only the effect of seasonal environmental changes, such as seawater temperature, but also the effect of reservoir pressure increase over the injection period. In this study, numerical modeling and analysis of offshore transport systems such as the long-distance subsea pipeline and riser, offshore platform including injection facilities, and subsurface wellbore, were carried out considering the subsea and subsurface conditions. The results showed that a careful phase-change control at the offshore platform was required to assure reliable injection over the life of a project. Since the conventional process involved heating only, a large amount of energy consumption was unavoidable. A new CO2 heating process using seawater and compressor discharge heat is proposed in this study. In terms of energy required on the offshore platform, the proposed process was 14-19% more efficient than the conventional process. In addition, key design parameters were derived and optimum operating conditions are suggested based on sensitivity studies.