Low-emission offshore Gas-To-Wire from natural gas with carbon dioxide: Supersonic separator conditioning and post-combustion decarbonation

Abstract

Gas-To-Wire is a solution for remote offshore oil-gas fields with high gas-oil ratio and high carbon dioxide content, as it requires minimum natural gas upgrade and is feasible for long-distance transportation. Additionally, combining offshore Gas-To-Wire with carbon capture enables abatement of emissions while providing revenues from enhanced oil recovery. This work investigated offshore Gas-To-Wire comprising processing of natural gas with high carbon dioxide content, power generation, post-combustion carbon capture and enhanced oil recovery. Supersonic separator is proposed for three applications: fuel-gas conditioning, fuel-gas decarbonation and pioneering dehydration of supercritical carbon dioxide. Economic analysis, including offshore rig and electricity transmission, results in positive Net Present Value with 20% of return-on-investment, besides a Levelized Cost of Energy comparable to onshore power plants with carbon capture and storage. Sensitivity analysis shows high impact of electricity-price and oil recovery yield on profitability, as well as better economic performance when carbon dioxide is not removed from fuel-gas; i.e., all carbon capture should be post-combustion capture. Thus, despite effectiveness of supersonic separator for fuel-gas decarbonation, the 612 MW optimized Gas-To-Wire with carbon capture plant should have 100% of carbon removal via post-combustion, resulting in 38.3% return-on-investment and even better Levelized Cost of Energy similar to onshore power plants without carbon capture.