1. PRESSURE PULSE ANALYSIS OF GAS LIFT WELLS
J.S. Gudmundsson, I. Durgut
Norwegian University of Science and Technology
7491 Trondheim
J. Rønnevig, K. Korsan, H.K. Celius
Markland AS
7462 Trondheim
2001 Fall ASME/API Gas Lift Workshop
November 12-13, 2001, Aberdeen

2. Contents of Paper Introduction Pressure Pulse Generation
Mass Flow Rate
Line Packing
Multiphase Mixtures
Operational Issues
Wells and Pipelines
Limited-Installation Test
Gas Lift Analysis
Concluding Remarks

4. Pressure Pulse Technology
Gas-Liquid Mass Rate
Flow Condition Analysis
Wells and Flowlines
Field Tested Offshore
On-Demand Testing
Quick-Acting Valve
Pressure Transducers
Patented World-Wide
Licensed to Markland

5. A B
LAB
Pressure
Time A B

6. Pressure Pulse Mass Rate No Calibration Needed
Δp (Pa) = ρ u a
a (m/s) = ΔL/ Δt
G (kg/s.m2) = ρ u
w (kg/s) = G A
w (kg/s) = Δp A/a

7. Pressure Pulse FLOW CONDITION ANALYSIS
A quick-acting valve stops the flow. The wellbore pressure drop needed to overcome wall friction during production, becomes available as static pressure at wellhead. This change in pressure propagates continuously at the speed of sound back to the wellhead. The resulting pressure-time log can be used in flow condition analysis. In-house rapid pressure transient and speed of sound models and commercial wellbore flow model used (convert to pressure-distance log).

9. Pressure Pulse Flow Condition Analysis Oil Producer Example2 4 7 6 9 3 5 10 8
Reflections:
1 = diameter change at 382 m
2 = diameter change above SCSSV
3 = diameter change below SCSSV
4,5,6 = secondary reflections
7 = Bubble point (2300 m)
8 = secondary reflection from bubble point
9 = diameter reduction before inflow zone
10 = bottom hole 1

10. Pressure Pulse Limited-Installation Test Offshore Well A
Measured depth 4440 m, vertical depth 2270 m
Tubing ID reduced from 4.89” to 3.55” at 650 m depth
Oil gravity 35 API, gas gravity 0.89
GOR 24.8 Sm3/m3, produced GOR 635 Sm3/m3
Liquid production rate 1167 Sm3/day, WC 66.8%
WHP 67 bar, BHP 234 bar
WHT 76 C, BHT 100 C
Void fraction at wellhead 0.63

12. 1100 meters
1750 meters
2100 meters

13. Pressure Pulse Gas Lift Analysis Well B
Vertical well 3500 m deep
Tubing ID 0.1 m
Gravity oil 32 API, gas 0.85, water 1.103
GOR 50 Sm3/m3, WC 50%
WHP 50 bara
Liquid production rate 400 Sm3/d
Gas injection rate 100 MSm3/d
Valves 1100 m, 1750 m and 2100 m depth

17. Pressure Pulse Analysis of Gas Lift Wells CONCLUDING REMARKS
Pressure pulse technology used for gas-liquid mass rate and wellbore flow condition analysis. On-demand testing.
Technology is flexible, robust and gives highly-repeatable results. Limited and extensive-installations tested offshore.
Location of active gas lift valve simulated for typical well using models of rapid transients, sound speed and wellbore flow models.
Pressure pulse technology can be used for a range of applications, including gas lift optimisation (allocation of injection gas).