Large subsea package deployment methods and devices
According to one or more embodiments disclosed herein is a method of transporting equipment between sea-surface and seafloor by providing a structure with equipment mounted thereon. The equipment may be liquid storage tanks, pumps, compressors, separators, metering systems, energy sources, communication systems, buoyancy tanks, and the like. The structure is used for disposal and installation in a subsea environment by changing the volume of buoyancy material within at least one buoyancy tank.
1. A structure, comprising:
at least one liquid storage tank, wherein the liquid storage tank comprises:
an outer container, wherein the outer container is rigid;
at least two inner containers comprising:
a first inner container containing seawater; and
a second inner container containing at least one stored liquid;
wherein the at least two inner containers are flexible;
wherein the at least two inner containers are pressure balanced; and
wherein the volume of the outer container remains fixed, and the volumes of the at least two inner containers are variable;
at least one open bottom buoyancy tank.
2. The structure of claim 1 , wherein the open bottom buoyancy tank comprises at least one vent hole along a side of the open bottom buoyancy tank.
3. A method of transporting at least one liquid storage tank between a sea surface and a seafloor, by:
providing a structure comprising:
an outer container, wherein the outer container is rigid;
at least two inner containers comprising:
a first inner container containing seawater; and
a second inner container containing at least one stored liquid;
wherein the at least two inner containers are flexible;
wherein the at least two inner containers are pressure balanced; and
wherein the volume of the outer container remains fixed, and the volumes of the at least two inner containers are variable;
at least one open bottom buoyancy tank;
changing a volume of buoyancy material within the at least one open bottom buoyancy tank.
4. The method of claim 3 , wherein the open bottom buoyancy tank comprises at least one vent hole along a side of the open bottom buoyancy tank.
5. The method of claim 4 , wherein changing the volume of buoyancy material within the at least one open bottom buoyancy tank comprises closing the at least one vent hole at a near surface depth.
6. The method of claim 3 , further comprising lowering the structure to the seafloor, wherein changing the volume of buoyancy material within the at least one open bottom buoyancy tank comprises adding at least a portion of the buoyancy material to the at least one open bottom buoyancy tank.
7. The method of claim 3 , further comprising lifting the structure from the seafloor, wherein changing the volume of buoyancy material within the at least one open bottom buoyancy tank comprises releasing buoyancy material from the at least one open bottom buoyancy tank.
8. The method of claim 7 , wherein the buoyancy material comprises at least one of air, nitrogen or spheres of buoyant material.
9. The method of claim 3 , further comprising pulling the structure with a surface support vessel.
10. The method of claim 3 , wherein changing the volume of buoyancy material comprises filling the at least one open bottom buoyancy tank with loose buoyancy materials through the use of water-buoyancy material slurry.
11. The method of claim 10 , wherein the water-buoyancy material slurry is added to the at least one open bottom buoyancy tank with a slurry lift pump.
12. The method of claim 3 , wherein the at least one open bottom buoyancy tank comprises an exit port closure.
13. The method of claim 3 , further comprising at least one subsea thruster package attached to the structure.
14. The method of claim 13 , further comprising controlling the at least one subsea thruster package with a remote operated vehicle.
15. The method of claim 13 , further comprising remotely controlling the at least one subsea thruster package.
16. The method of claim 13 , wherein the at least one subsea thruster package is powered through an umbilical.
17. The method of claim 16 , wherein the at least one subsea thruster package is powered using at least one battery.
18. The method of claim 3 , further comprising using at least one subsea pull-down winch with a motion compensated hoisting line to control the positioning and lowering of the structure onto at least one seafloor support.
19. A method of transporting equipment between sea-surface and seafloor, by:
providing a structure comprising:
an outer container, wherein the outer container is rigid;
at least two inner containers comprising:
a first inner container containing seawater; and
a second inner container containing at least one stored liquid;
wherein the at least two inner containers are flexible;
wherein the at least two inner containers are pressure balanced; and
wherein the volume of the outer container remains fixed, and the volumes of the at least two inner containers are variable;
at least one open bottom buoyancy tank;
changing a volume of buoyancy material within the at least one open bottom buoyancy tank; and
wherein said equipment is mounted on the structure and is selected from a group consisting of liquid storage tanks, pumps, compressors, separators, metering systems, energy sources, and communication systems.
20. The method of claim 19 , wherein the structure provides a stable sea-floor foundation for the support and operation of the equipment mounted thereon.