Horizontal three-phase separator

A three-phase separator is a pressure vessel that takes the well stream and splits it into three streams: gas at the top, oil in the middle and water at the bottom. Separation relies on density difference and residence time, while the control system holds the oil and water levels and the operating pressure.

How to use the simulator

• Start flow: turns the well stream on or off.
• See-through: makes the shell transparent so you can see the layers and the weir.
• Inlet rate: slider for the inlet rate, 25% to 150%.
• Problem: picks a fault: oil LCV stuck closed, water LCV stuck closed, or gas PCV stuck closed.
• Drag: rotate the figure with a finger or the mouse; + and − to zoom.

How each part works

• Inlet nozzlethe well stream enters; the inlet device breaks its momentum and separation starts.
• Gravity sectionthe liquid calms down: gas rises, oil and water separate by density.
• Weiran internal dam: oil spills over into the oil bucket, water stays behind.
• Oil LC / Oil LCVthe oil level controller opens or closes the oil outlet valve to hold the level.
• Interface LC / Water LCVmeasures the oil-water interface and dumps water through its valve.
• PCVpressure control valve on the gas outlet; holds the operating pressure.
• PSVpressure safety valve: opens if pressure exceeds the design limit.
• Sight glass / PI gaugelevel glass and pressure gauge for field checks.

Simplified teaching model: not to scale, and the numbers are illustrative. Real design and operating values come from the manufacturer data and your company procedures.

Sources

1. SLB Energy Glossary: “three-phase separator”, “separator”
2. API Spec 12J: Specification for Oil and Gas Separators
3. GPSA Engineering Data Book, Section 7: Separation Equipment
4. Arnold, K. & Stewart, M. Surface Production Operations, Vol. 1
5. Wikipedia: Separator (oil production)

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