Active Control of Gas Lift Wells Simulation and Experimental Series

1
Active Control of Gas Lift WellsSimulation and
Experimental Series

• Gisle Otto Eikrem
• Department of Engineering Cybernetics
• Norwegian University of Science
• and Technology

2
Overview Gas Lift Wells

• Instability in multiphase flow
• Stabilization methods
• Simulaton results
• Experimental results
• Summary

3
Gas Lifted Well
Well Data 2048 m vertical well 5 inch
tubing 2.75 inch production choke 0.5 inch
injection orifice
Annulus
Tubing
4
Unstable Flow
5
Production Curve
Optimal region
Theoretical production
Stable region
Unstable region
6
Introduction Video I
7
Multiphase Video I
Video of severe slugging in gas lift well
8
Introduction Video II
9
Multiphase Video II
Video of controlled multiphase flow Stable flow
10
Stabilizing Options

• How to stabilize severe slugging in gas lift
  wells
• Choking
• Size of orifice / critical flow
• Increase gas rate
• Automatic control

11
Minimum Flow Curve
Gravity dominated pressure drop -
unstable friction dominated pressure drop - stable
Gravity
Friction

• Gravity dominated - small rate reduction
• Pressure increase
• Decreasing inflow
• Unstable!

• Friction dominated - small rate reduction
• Pressure decrease
• Increasing inflow
• Stable

12
Control Principle
The Principle behind control of severe slugging
in gas lift wells

• Stabilize pressure in bottom of well
• Production choke controls pressure

PT
13
Control Structures
Casing Head Pressure
Downhole Pressure
14
OLGA Results
Control of Downhole Pressure
15
OLGA Results
Control of Casing Head Pressure
16
The Laboratory
Production Tubes
Control Panel
Reservoir Valve and Gas Injection
17
Laboratory Setup
18
Control Structures
Casing Head Pressure
Downhole Pressure
19
Experimental Results
Control of Downhole Pressure
20
Experimental Results
Control of Casing Head Pressure
21
Summary

• How to stabilize gas lift wells
• Possible control structures
• Simulation results
• Laboratory experiments