1. TPG 4105 NTNU PROCESSING OF PETROLEUM Compression
Professor Jon Steinar Gudmundsson
Department of Petroleum Engineering and Applied Geophysics
Norwegian University of Science and Technology
Trondheim
November 8, 2013

2. Compression in Oil and Gas Production
Recompression in separation train of gas and condensate (same as in oil production).
Export compression (from platform to pipeline).
Reinjection compression (from platform to subsurface).
Various air compressors for control equipment in processing facilities (offshore and onshore).
Export compression, from receiving and processing terminal to pipeline.
Pressure boosting, onland compression.
Gas storage in salt caverns.
Subsea compression (now being installed)

3. A: Recompression, B: Gas Drying, C: Fuel Gas, D: Export Compression, E: Gas Pipeline, F: Injection Compression, G: Injection Well

5. Offshore Gas Turbines
The oil and gas industry in 2007 represented 25 % of CO2 emissions in Norway. 70 % is offshore (combustion, diesel and flaring)
Requirement for electricity offshore 2007 was 15 TWh (Norway’s total electricity production was then about 125 TWh).
In 2007 there were 167 gas turbines on offshore installations amounting to 3000 MW.
About 45 % of the power is for electrical equipment. The remaining power is gas turbines for compressors and other equipment.
The thermal efficiency of the gas turbines is in the range %.
Thermal recovery is used in most of the installations, increasing the thermal efficiency to about 40 %
Kraft fra land til norsk sokkel (2008), OD o.a.

6. Types of Compressors Reciprocating piston compressors
Low flow rate
High compression ratio
Rotating centrifugal compressors
High flow rate
Low compression ratio each stage
Several stages higher compression ratio

7. Radial Flow Compressor

8. Centrifugal Compressor

10. Axial Flow Compressor

11. Subsea Compressor

12. Characteristic Curve

13. Characteristic Curves
Left: Radial,
Middel: xxx,
Right:Axia
A: Centrifugal, B: Axial, C: Piston, D: Screw

14. Thermodynamic Processes
Condition
Exponent
Adiabatic
Isobaric
Isothermal
Isentropic
Polytropic
Isometric
dq=0
dp=0
dT=0
ds=0
∑ds=0
dV=0
k=Cp/Cv
k=0
k=1
k<n
k=∞
Reversible adiabatic process = Isentropic process

15. Compressor Work
A = Suction, B = Compression, C =Delivery, D = Expansion

16. Adiabatic/Isentropic Process

17. Adiabatic/Isentropic Compression
v [m3/mol], p [Pa=N/m2], W [Nm/mol=J/mol] = Specific work
pv=RT, Wm/M [J/mol kg/s mol/kg=J/s=W] = Power

18. Ideal Gas Compression m (kg/s) 70 M (kg/kmol) 20,43 R (J/kmolK)
8314,34
T innløp C 30
k (Cp/Cv)
1,26
p innløp bara 80
p utløp bara
160
P (MW)
6,44
T utløp C 77

19. Surge and Stone Wall
A: Surge line, B: Stonewall line

20. Surge Control

21. Compression in Two Stages
Above pressures give minimum power

22. Compression in Two Stages

23. Hedne (2013)

24. Summary Compression in oil and gas industry
Offshore compression/compressors
Types of compressors
Characteristic curves P [W] or h [J/kg] vs. q [m3/h]
Calculation of compression power (isentropic)
Surge and surge control
Compression in stages with intercooling (minimum power when equal power)
Subsea compression