1. ANGOLA OIL AND GAS HYDRAULIC FLUIDS FOR USE OFFSHORE ANGOLA
SIMON McMANUS
Wm CANNING Ltd.

2. HYDRAULIC FLUIDS FOR USE OFFSHORE ANGOLA
Basics of subsea control
Subsea control in Angola
Environmental Considerations
Water depth
Static pressure head
Long umbilicals

3. Basics of Subsea Control
Valves that control oil/gas flow and well injection are installed on the seabed.
These subsea templates or single wells are controlled remotely from a nearby platform or floating production vessel.
The control is via hydraulic umbilical line.

4. Basics of Subsea Control

5. Advantages of Subsea Control in Angola
Can be used in deep water.
A cheaper method of producing from large areas.

6. Influencing Factors For Subsea Control Fluid in Angola
Water depth
Well pressures
Environmental legislation.

7. Environmental Considerations
From an engineering perspective it is advantageous to discharge subsea hydraulic fluid into the marine environment.
Power Loss
System response time
Cost

8. Environmental Issues
If fluid could be discharged into the ocean it would:-
Reduce the cost of umbilicals
Increase the performance of the subsea control system
Increase safety

9. Environmental Issues Hydraulic oils are not acceptable for discharge.
Angolan legislation is currently being formulated.
EU legislation governing the use of chemicals states that an HOCNF document is required.

10. The HOCNF Biodegradability of all the components in the formulation.
Bioaccumulation of all the chemicals in the formulation.
Toxicity of the finished product on:-
Fish
Crustacean
Algae
Sedimentary re-worker

11. The Influence of The HOCNF
No chemical that is bio-accumulative can be used in hydraulic fluid formulations
All the components in the formulation are at least 20% biodegradable in 28 days, testing is done in non attenuated bacteria

12. Toxicity Testing

13. Toxicity Improvements
Older fluids had LC50 values in the region of 1-10 mg/l
New fluids have LC50 values in the region of mg/l
This is 1000 times less toxic

14. Extreme Water Depth Reliability is paramount due to work-over cost.
Stability of the fluid and compatibility is essential.
Static pressure head becomes significant.

15. Hydrostatic Pressure Head
WATER-BASED
HYDRAULIC FLUID
SEAWATER
HYDRAULIC OIL
Foinaven m
61.5 BAR BAR BAR
11.94 BAR BAR
Girasol 1405m
144 BAR BAR BAR
28 BAR BAR

16. Pressure Differentials

17. Hydrostatic Pressure Head
Water-based
Oil-based

18. Long Umbilical Lengths

19. Long Umbilical Lengths
Pressure
1 BAR
Water-based
Hydrocarbon-based

20. Long Umbilical Lengths
Narrow hydraulic lines will require more time to pressurise using an oil based material due to compressibility and viscosity
The system will be “springy”
If a line is made redundant the fluid in that line is likely to end up in the ocean

21. A point to be made
There is a definite engineering advantage in using environmental fluids in Angola
Low viscosity
Low compressibility
High specific gravity
Environmental alternatives are not always more expensive