Method for thermally protecting subsea installations, and apparatus for implementing such thermal protection
View Patent ↗Method for protecting subsea installations against cooling which leads to hydrate formation, in particular during production halts. This is achieved by thermally isolating portions of the installation ( 1 ) against the surrounding water ( 2 ), and particularly by completely encompassing the subsea installation ( 1 ) by means of a cap ( 3 ) which seals against the surrounding water ( 2 ). The cap ( 3 ) comprises several elements of which each separately can be exposed to cooling and internal hydrate formation. The invention also comprises a thermally isolating apparatus, adapted for protecting subsea installations ( 1 ) against cooling, which involves a risk for hydrate formation. An apparatus ( 3, 9 ) for implementing the method comprises a relatively tight-fitting cap ( 3 ) which encompasses at least two of the elements to be protected from cooling. Thus, the water inside the cap ( 3 ) is kept separately from the surrounding water ( 2 ) and evenly distribute the heat energy present under the cap ( 3 ) to all the elements encompassed by the cap.
1. A method for protecting a subsea installation against cooling which leads to hydrate formation, in particular during interruption of production, by having parts of the installation ( 1 ) thermally insulated against the surrounding water ( 2 ),
wherein the subsea installation ( 1 ) is completely or partially encompassed by a cap ( 3 ) which seals against the surrounding water ( 2 ), whereby the cap ( 3 ) encloses several elements which each separately can be subjected to internal hydrate formation, a bottom plate ( 9 ) is placed on a foundation ( 10 ) under water ( 2 ), the subsea installation ( 1 ) is placed on the bottom plate ( 9 ), the cap ( 3 ) is lowered onto the bottom plate ( 9 ) and is attached thereto; and
wherein the cap ( 3 ) and the bottom plate ( 9 ) are attached to each other by fastener elements ( 19 , 20 ).
2. The method according to claim 1 , wherein the cap ( 3 ) is provided with a pressure resistant, thermal insulation ( 4 ) at its surface ( 5 ).
3. The method according to claim 1 , wherein the cap ( 3 ) is designed as a sandwich shell structure ( 6 ) having double walls, and thermal insulation ( 4 ) is provided between the sandwich double wails ( 7 , 8 ).
4. A thermally insulating assembly adapted to protect a subsea installation ( 1 ) against cooling which leads to a risk of hydrate formation,
wherein the assembly ( 3 , 9 ) comprises a relatively tightly enclosing cap ( 3 ) for surrounding at least two of the elements which it is desired to protect against cooling, so that the water within the cap ( 3 ) is kept separated from water ( 2 ) in the surroundings and distributes heat energy present under the cap ( 3 ) to all of the elements enclosed thereby, wherein the assembly further comprises a bottom plate ( 9 ) having side edges ( 12 ) which are shaped substantially to be complementary to the side edges ( 13 ) of the can ( 3 ), so that there is left room for required pipe and cable connections to the installation ( 1 ).
5. A thermally insulating assembly according to claim 4 , additionally comprising at least one internally located temperature detector ( 14 ).
6. A thermally insulating assembly according to claim 4 , wherein at least one of the bottom plate ( 9 ) and the cap ( 3 ) is provided with sealing elements ( 25 ) along the periphery thereof and at openings in the structure.
7. A thermally insulating assembly according to claim 4 , wherein the cap ( 3 ) includes at least two separate cap components ( 16 , 17 , 18 ).
8. A thermally insulating assembly according to claim 7 , wherein the cap components ( 16 , 17 , 18 ) are provided with fastening devices ( 19 , 20 ) which can be joined in a detachable manner.
9. A thermally insulating assembly according to claim 4 , further comprising at least one temperature detector ( 14 ) as well as at least one heating element ( 22 ).
10. A thermally insulating assembly according to claim 4 , further comprising at least one intake ( 23 ) and at least one outlet ( 24 ) for fluid, so that the fluid inside the assembly can be exchanged.
11. A method for protecting a subsea installation against cooling which leads to hydrate formation, in particular during interruption of production, by having parts of the installation ( 1 ) thermally insulated against the surrounding water ( 2 ), wherein:
the subsea installation ( 1 ) is at least partially encompassed by a cap ( 3 ) which seals against the surrounding water ( 2 ), whereby said cap ( 3 ) encloses several elements which each separately can be subjected to internal hydrate formation,
a bottom plate ( 9 ) is placed on a foundation ( 10 ) under water ( 2 ),
the subsea installation ( 1 ) is placed on the bottom plate ( 9 ),
the cap ( 3 ) is lowered onto the bottom plate ( 9 ) and is attached thereto, the cap ( 3 ) having an internal cavity ( 11 ) with such a shape and size as to make the cap ( 3 ) cover the installation, whereby the cap ( 3 ) and the bottom plate ( 9 ) have complementary shapes along the periphery and are located so as to fit sealingly to each other;
and wherein the cap ( 3 ) and the bottom plate ( 9 ) are attached to each other by fastener elements ( 19 , 20 ).
12. A method according to claim 11 , wherein the cap ( 3 ) is provided with a pressure resistant, thermal insulation ( 4 ) at its surface ( 5 ).
13. A method according to claim 11 , wherein the cap ( 3 ) is designed as a sandwich shell structure ( 6 ) having double walls ( 7 , 8 ) and that thermal insulation ( 4 ) is provided between the sandwich double walls.
14. A thermally insulating assembly adapted to protect subsea installations ( 1 ) against cooling which leads to a risk of hydrate formation,
wherein the assembly ( 3 , 9 ) comprises a relatively tightly enclosing cap ( 3 ) for surrounding at least two of the elements which it is desired to protect against cooling, so that the water within the cap ( 3 ) is kept separated from the water ( 2 ) in the surroundings and distributes the heat energy being present under the cap ( 3 ) to all the elements being enclosed thereby, and wherein said assembly additionally comprises at least one internally located temperature detector ( 14 ).
15. A thermally insulating assembly according to claim 14 ,
wherein the assembly comprises a bottom plate ( 9 ) having side edges ( 12 ) which are shaped substantially to be complementary to the side edges ( 13 ) of the cap ( 3 ), so that there is left room for required pipe and cable connections to the installation ( 1 ).
16. A thermally insulating assembly according to claim 14 , wherein at least one of the bottom plate ( 9 ) and the cap ( 3 ) is provided with sealing elements ( 25 ) along the periphery thereof and at openings in the structure.
17. A thermally insulating assembly according to claim 14 , wherein the cap ( 3 ) includes at least two separate cap components ( 16 , 17 , 18 ).
18. A thermally insulating assembly according to claim 17 , wherein the cap components ( 16 , 17 , 18 ) are provided with fastening devices ( 19 , 20 ) which can be joined in a detachable manner.
19. A thermally insulating assembly according to claim 14 , further comprising at least one heating element ( 22 ).
20. A thermally insulating assembly according to claim 13 , further comprising at least one intake ( 23 ) and at least one outlet ( 24 ) for fluid, so that the fluid inside the assembly can be exchanged.