Summary
Efficient and effective oil/water/gas separation is required for success of
many production operations. A major oil producer was experiencing difficulties
with the oil/water/gas separation equipment on an offshore platform and
improvements were required to meet both present and future production rates.
Both high-pressure (HP) and low-pressure (LP) separators on a major oil
production platform were studied to determine the design limitations for foamy
service and basic sediment and water (BS&W) levels.
Computational-fluid-dynamics (CFD) studies were completed to show the
volumetric utilization and flow-pattern improvements made with the design
changes.
Both HP and LP separators showed substantial foam and poor efficiency
because of poor inlet-device design, plugging, and other general vessel-design
limitations. Debottlenecking efforts determined that, while the inlet device
was somewhat ineffective, major improvements could be made from changes to
perforated plate baffles, fluid-level adjustments, and weir placement and
operations.
CFD calculations performed on both vessels indicated similar problems. The
perforated plate baffles with improper design lead to countercurrent flow
through the baffles, making them less effective in flow control and
distribution. Fluid-level settings for the weir height affected the velocity
differences between fluid layers and contributed to promotion of recirculation
within the vessel, which lead to low volumetric utilization.
With adjustments to vessel internal equipment and changes to fluid-phase
levels, CFD calculations showed that overall vessel volumetric utilization was
improved by 22% for the HP vessel and by 38% for the LP vessel. CFD results
also showed the changes to the flow patterns accompanying these
improvements.
Vessels with the proposed changes were operating effectively with
substantially higher throughputs and meeting the expected BS&W levels for
operations of the downstream oil-processing equipment. Details about the vessel
internals, flow properties, and other changes required to accomplish these
improvements will be discussed.
© 2009. Society of Petroleum Engineers
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History
- Original manuscript received:
16 June 2008
- Meeting paper published:
21 September 2008
- Revised manuscript received:
30 December 2008
- Manuscript approved:
13 January 2009
- Published online:
14 January 2010
- Version of record:
14 January 2010
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