1. Active Control of Gas Lift Wells Simulation 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
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3. Gas Lifted Well Well Data: Annulus Tubing · 2048 m vertical well
0.5 kg/s
15bara
Well Data:
· 2048 m vertical well
· 5 inch tubing
· 2.75 inch production choke
· 0.5 inch injection orifice
Annulus
Refer to the number of gas lifted wells in Shell, “ wells worldwide are operated with gaslift. Shell produces
about barrels/day from gaslifted wells".
Tubing
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4. Unstable Flow
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5. Production Curve Optimal region Theoretical production Stable region
Unstable region
The optimal region is given from the object function which includes the production and price of oil and gas and the cost related to the gas injection rate. There may also be limitations in the availability of lift gas and compressor capacity.
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6. Introduction – Video I
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7. Multiphase Video I Video of severe slugging in gas lift well
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8. Introduction – Video II
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9. Video of controlled multiphase flow
Multiphase Video II
Video of controlled multiphase flow
Stable flow
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10. Stabilizing Options How to stabilize severe slugging in gas lift wells
Choking
Size of orifice / critical flow
Increase gas rate
Automatic control
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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
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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
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13. Control Structures Casing Head Pressure Downhole Pressure
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14. OLGA Results
Control of Downhole Pressure
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15. OLGA Results
Control of Casing Head Pressure
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16. The Laboratory Production Tubes Control Panel Reservoir Valve and
Gas Injection
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17. Laboratory Setup
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18. Control Structures Casing Head Pressure Downhole Pressure
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19. Experimental Results
Control of Downhole Pressure
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20. Experimental Results
Control of Casing Head Pressure
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21. Summary How to stabilize gas lift wells Possible control structures
Simulation results
Laboratory experiments
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