1. SUBSEA GAS BOOSTING Jon Steinar Gudmundsson October 8, 2008

2. Alphabeta Production Gas initially in place 94.4×109 Sm3
Reserves in place
56.6×109
Daily volume flow rate (total)
7.75×106
Sm3/d
Hourly mass flow rate (total)
239×103
kg/h
Number of wells 4
Tubing diameter (ID)
0.15 m
Hourly mass flow rate per well
61×103
Molecular weight
17.45
kg/kmol

3. Alphabeta Natural Production 4 Wells

4. Alphabeta Pressures Constant Total Field Rate 240,000 kg/h
Year
WHP
(bara)
PLEM
Difference
(bar)
234
176 2
209
157 19 4
193
145 31 8
159
119 57 16 91 68
108
PLEM = Pipeline End Manifold (75% of WHP)

5. Industrial Jet Pump
pipe
mixer
diffuser
nozzle

6. Pump Performance
ESDU industrial jet pump experience and performance data used in calculations
Pressure loss coefficients for LP, HP, M and D sections in series, K=(Δp)/(0.5ρu2)
Performance numbers M, N, R, η, C in terms of flow, pressure, geometry, hydraulic efficiency and density
Review of literature of jet pumps in single and multiphase service

7. Performance Numbers

8. Performance Equation

11. Alphabeta Pump Parameters
Year
Difference
(bar) C
(-) N M η
0.23
0.00 2 19
0.21
0.15
1.9
0.29 4 31
0.19
0.25
1.6
0.40 8 57
0.46
0.90
0.41 16
108
0.084
0.87

12. Alphabeta Drive Fluid Rate
Year
Difference
(bar)
Gas Density
(kg/m3)
Gas Flow Rate
(m3/h) M
(-)
Drive Fluid
139
1719 2 19
124
1927
1.9
1039 4 31
114
2096
1.6
1343 8 57 92
2598
0.90
2962 16
108 50
4780

13. Drive Fluid Volume Rate and Mass Rate
Year
Difference
(bar)
Drive Fluid
(m3/h)
(kg/h)
(-) 2 19
1039
622,000 4 31
1343
803,000 8 57
2962
1,770,000 16
108

14. Subsea Gas Boosting

15. Alphabeta Phase Envelope

16. Alphabeta Hydrate 100% and 75% Produced Gas + 25% Drive Fluid
75+25%

17. Pipeline Diameter Constant Gas Production, Increasing Drive Fluid

18. CFD Simulation

19. Performance Simulation (CFD)

20. Concluding Remarks
Field and well performance assumed; high quality offshore resource
Performance of jet pumps well known, but not for HP natural gas (K factors?)
High drive fluid rate and hence large pipe diameter (dense phase transport)
14% greater cumulative production first 8 years with pressure boosting

21. Alphabeta Natural Gas Field
Drainage area 80
km2
Reservoir thickness 25 m
Average reservoir pressure
285
bara
Average reservoir temperature 88 oC
Water depth
800
Reservoir depth
2600
Average permeability
200 mD
Porosity  %
Water saturation 20 %
Recovery factor 60
Life time of reservoir
Years

22. Alphabeta Pressures Constant Total Field Rate 240,000 kg/h
Year G
[GSm3]
p/z
[bara] p
BHP
WHP 2
5,7
287
264
258
209 4
11,3
268
246
239
193 8
22,6
232
200
159 16
45,3
136
124 91

23. Alphabeta Reservoir Performance

24. Alphabeta Inflow Performance

25. Pressure Loss Coefficients ESDU