Towards Sustainable Energy: Integrated Subsurface-Surface Modeling for Multiphase Pump Deployment to Enhance Production and Decarbonization in Legacy Oil Field

Abstract In a large offshore UAE carbonate oil field, production performance of wells has been adversely affected by advanced reservoir maturity and water breakthrough resulting from peripheral and Inner ring water injection. The existing facilities, constructed over 50 years ago, face challenges such as high sea-line export pressure and the absence of an artificial lift system. This paper discusses deployment of multiphase pump using integrated subsurface and surface modeling approach to enhance oil production. Flow tests were utilized to update the Well model for existing wells, providing accurate well productivity. Well decline curves, depicting watercut and gor evolution with cumulative oil production, were derived from the Reservoir Simulation model. These curves, alongside the well model, were integrated into Surface Model, encompassing all pipeline network and multiphase pump description. Under high wellhead conditions, even low water-cut wells can become un-eruptive post-shutdown, necessitating frequent vessel unloading in offshore settings, leading to significant downtime. Script implemented in Integrated Model, considering parameters like well deviation, completion, fluid composition, velocities, wellhead and reservoir pressure, biannually evaluates well eruptivity and applies downtime accordingly. The existing subsea production network was evaluated using an integrated model, with and without a multiphase pump. The integrated model shows that under similar subsurface conditions, platforms with a multiphase pump could produce about 20% more oil. The model also helps in finding the size, specification, and power requirement for the pump. It also gives the best position for installing the pump. It shows that putting the pump near the wellhead towers would reduce the pressure loss in surface pipelines, leading to lower wellhead pressure and longer well life. Without the pump, a barge or vessel is used to unload wells that cannot flow naturally, which leads to flaring and venting of gas. The integrated model shows that the multiphase pump would significantly decrease well downtime and reduce the need for unloading operations, leading to lower carbon emissions. Currently, hydrocarbon gas is injected into the gas cap to maintain pressure. The multiphase pump would allow wells to produce with higher watercut, which would enable switching from gas injection to water injection in the future for pressure maintenance. Since offshore gas injections contribute a lot to carbon emissions, switching to water injection would greatly lower carbon emissions. Integration of subsurface and surface model considering the issue of well startup using un-eruptive script has not been done before. This paper presents a way to enhance oil production in cost effective way in the ageing field. This has resulted in a better understanding of the transition phase and better scheduling of the sequence of modifications of the production facilities.