Optimal CO₂ allocation for enhanced oil recovery operations within carbon utilisation networks in Qatar

Carbon capture and storage (CCS) is one of the mostefficienttechniques for reducing carbon dioxide (CO₂) emissions into the atmosphere. Combining CCS with enhanced oil recovery (EOR) processes is a very attractive method for carbon capture and utilisation (CCU). These operations enable CO₂ emissions to be reducedthroughgeological sequestration, whilstgenerating additional revenue from enhanced oil production due to CO₂ re-injection via EOR. In practice, mass balance and temporal features of a given location are considered when planning EOR operations. When numerous oil reservoirs are involved, it is vital to allocate available CO₂ supplies and schedule EOR operations for these reservoirs at suitable timings. As a result, CO₂ allocation and scheduling are crucial for maximising the economic benefits of EOR operations. As such, this study introduces a resource trade scheme for CO₂ integration and utilisationwithin the state Qatar, where a mixed integer linear programming (MILP) model is developed to address CO₂ allocation and schedulingbased on environmental and economic objectives. The model considersa single CO₂ source (Qatar Gas) within an multi sink scenario which ORYX GTL, Dukhan Field Well (EOR)). Two scenarios are considered to allocateCO₂ to different sinks (including EOR) to obtain the optimal solution for each scenario. The outcome of scenario 1 demonstrates that the optimal solution is to utilize 13.5Mt/y of carbon dioxide, which results in an annual profit varying from 14.3 to 42.8 billion US dollars. The maximum CO₂ utilisation occurs at Dukhan Field Well (EOR), which utilises up to 67%. Scenario 2 is implemented based on scenario 1 to further improve the model; where the profit increased annually, and the model became more sustainable.