Evaluation of De-oiler Performance Using Numerical CFD Technique
Master thesis

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Date
2020Metadata
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- Master i teknologi [169]
Abstract
When producing oil from the reservoir, it comes together with water, gas, sand, and other
impurities. Excluding gas, all of them are unexpected waste. The water or simply called
produced water is the biggest problem due to its quantity and oil content. A produced
water treatment should be performed before it is discharged to the sea or re-injected into
the wells. External partner of this thesis, Subsea 7 is now developing a subsea separation
technology called SPU (Subsea Processing Unit). SPU consists of some separation units,
one of them is a de-oiler/hydrocyclone. This thesis will only focus on the de-oiler unit to
reduce oil concentration in the produced water to be under 20-30 ppmv.
A literature review is conducted to choose de-oiler geometry based on separation
efficiency. SALOME is used to draw and make a de-oiler mesh. The CFD simulation is
conducted using OpenFOAM with the Euler-Euler model. twoPhaseEulerFoam solver is
modified from its original example called bubbleColumn. The literature review has been
done to examine various geometry and types of de-oiler for oil and water. Based on
efficiency, the geometry for simulation is selected. From the results, the oil volume
fraction in the water is found to be high which leads to low efficiency. The pressure drop
is obtained to be very low compared to most of the literature, which is 0.02272 bar for
54.696 L/min and 0.0424 bar for 82.045 L/min. With the assumption of efficiency 76%,
the number of de-oilers needed to separate 60000-80000 barrels of produced water per
day varies between 25-162.