Optimization of Gravity Oil Separators: conventional vs. novel internals design
Overview: Primary oil/water separation is employed in oil industry to remove water from oil, which can be naturally present or injected to enhance production by helping force oil to the surface. Both formation and injected water eventually arrive to the well bore and are produced at the well head along with desired hydrocarbons. The bulk of suspended oil in produced water is free oil, and can be removed by means of gravity separation as the primary step of treatment.
The challenge: The separation process may not be as effective for emulsified hydrocarbons. Further, the presence of gas in the production stream from the wellhead generates a three-phase flow, which needs then to be separated into a gas phase for recovery, an oil phase for dehydration and transport, and a water phase for treatment.
TransAT Solution: The simulation work request and performed by TransAT was intended to help design such systems by testing variable flow entry procedures, with the objective to increase the liquid capacity of the vessels, minimizing the momentum of flow at the injection in the vessel. By combining various modelling capabilities in TransAT, including Interface Tracking to separate gas from liquid phases, and the Eulerian field formulation to track the emulsion of water, we could propose a new injection mechanism capable to break injected mixture momentum, lowering the jet penetration in the vessel, which all lead to a 22% longer residence time in the vessel. With these results, ARAMCO could simply change the injection systems in the thousands separation vessels in their production fields, without replacing them, which practically translates into a saving of hundreds millions of USD.
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Dr Mathieu Labois
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