Offshore offloading of CO₂: Review of single point mooring types and suitability

There are many types of single point mooring (SPM) and loading systems that have been developed in the offshore Oil and Gas sector for the transfer of hydrocarbon and other fluids from production wells, platforms or floating storages to tankers. Several of them can probably be adapted for transfer, in the opposite direction, of carbon dioxide (CO2) transported by ship as a refrigerated liquid, to injection wells for enhanced oil recovery (EOR) or geological storage. However, no clearly favoured offloading system for CO2 has emerged yet (Brownsort, 2015). This brief, desk-based study, carried out by Scottish Carbon Capture & Storage (SCCS) as part of the CATO-TKI project Transportation and unloading of CO2 by ship – a comparative assessment, looked at the types of SPM available, their key characteristics and potential suitability for CO2 offloading. The study developed a flow-chart based selection guide for a CO2 offloading mooring taking account of some constraints of location, material and equipment characteristics and operations. It also considered the fit of potential mooring systems to the outline process route options developed earlier in the project. However, recommendations of mooring systems are not possible at the current stage of the project, as case study data has not yet been finalised.