1. 1 Gas Hydrate basics

2. 2 Gas Hydrates Ice-like, crystalline solid May exist at temperatures up to 25 ° C at high pressure ‘Practical discovery’ by Hammerschmidt, 1934: Hydrates, not ice, were blocking North American gas pipelines = + 180 Sm 3 gas 1 m 3 hydrate 0.8 m 3 water

3. 3 Ice-like, crystalline solid May exist at temperatures up to 25 ° C at high pressure Requirements: - light hydrocarbons (C1-C4) - free water - “low” temperature (offshore: 20 bar) Gas Hydrates

4. 4 Hydrates in comets Makogon (1987) claimed that Halley’s comet consists of sand, rocks, and large amounts of CO 2 -hydrates, based on observed gas blowouts when the comet approached the sun. Photo: MWO Museum Exhibit

5. 5 Hydrates in our solar system Saturn - Average temp: -220°C - Outer ring: hydrate lumps up to 10 m in diameter? Pluto - Average temp: -230 °C - Methane and water in large amounts Picture by NASA Pluto Charon Pictures by NASA

6. 6 Saturn’s largest moon: Titan -180°C, liquid methane and ethane January 2005 Huygens landing Methane hydrate plain?

7. 7 Hydrates in the earth Hydrates exist in enormous amounts in permafrost regions and in deep ocean floors. These in-situ hydrates might: prove to be enormous energy resources be a factor in possible global climate change lead to sea floor instabilities

8. 8 Storegga landslide (7-8000 years ago)

9. 9 Seafloor hydrate occurrences ref: Naval Research Laboratory

10. 10 Hydrates in petroleum production A hydrate plug might form about anywhere the conditions are favorable: wells, X-mas trees, manifolds, jumpers, production pipelines, export pipelines, production risers, export risers, separators, valves, flanges, orifices, dead-legs, instrumentation lines, pipe bends etc.

11. 11 Microscopic structure Structure II hydrate: unit cell 16 8 Water lattice/cavities in hydrates

12. 12 Appearance Ca. 1 cm Gas system Oil system Hydrate crystal

13. 13 Hydrate equilibrium Hydrates Safe area Temperature Pressure Hydrate existence limit

14. 14 Effect of water composition on the hydrate curve

15. Multiphase Transport TEMPERATURE PRESSURE 0 m Depth 7000 m 1: onshore well 1 WAX HYDRATES ? 2: deep offshore 2 Original slide courtesy of Emile Leporcher, Total

16. 16 Hydrate kinetics Induction time: hours/days in stability region without hydrates Growth rates: - heat and mass transfer controlled - influenced by flow PRESSURE TEMPERATURE

17. 17 Hydrate kinetics time Hydrate amount Induction time How long ??? Formation rate How big ??? Formation period How long ???

18. 18 Demonstration...