Optimize Three-Phase Separator Control to Prevent Carryover

The Issue

Three-phase separators are critical for oil, gas, and water separation, but poor level control leads to:

• Liquid carryover to gas compression (causing compressor damage)
• Water in oil export (quality give-aways)
• Oil in produced water (environmental compliance issues)

Default PID tuning rarely accounts for separator-specific dynamics like varying inlet compositions and flow surges.

The Fix

Systematic Controller Optimization:

1. Characterize Dynamics: Perform step tests to understand level response time
2. Tune Cascade Loops: Optimize both oil/water interface and gas/liquid interface controls
3. Account for Interactions: Consider coupling between level loops
4. Implement Anti-Surge Logic: Handle rapid inlet changes from upstream upsets

For challenging applications, consider advanced control strategies like model predictive control (MPC) or feedforward compensation.

Benefits

Properly tuned separator controls deliver:

• 95%+ separation efficiency vs. 80-85% with poor control
• Zero liquid carryover events to downstream equipment
• Reduced chemical treatment costs for water cleanup
• Improved export quality and reduced demurrage claims