초록 ▼

An offshore well platform is towed in an upright condition to a well site by the use of a temporary flotation device. The flotation device mounts to a portion of the platform and is partially submerged, increasing the ability and buoyancy of the platform. At the site, the engagement of the flotation

An offshore well platform is towed in an upright condition to a well site by the use of a temporary flotation device. The flotation device mounts to a portion of the platform and is partially submerged, increasing the ability and buoyancy of the platform. At the site, the engagement of the flotation device shifts to a deploying position. In the deploying position, the ballast of the platform is increased to cause it to more deeply submerge. The flotation device remains at least partially surrounding the platform and floating while the platform moves downwardly relative to it. This provides lateral support if needed to prevent heeling while being submerged. The flotation device is disengageable from the platform when the platform is fully submerged.

대표청구항 ▼

1. A method for deploying an offshore well facility, comprising:(a) providing a platform with a variable ballast;(b) fastening a flotation device to the platform in a manner to increase buoyancy of the platform, the flotation device causing the platform to float in a towing position with the platfor

1. A method for deploying an offshore well facility, comprising:(a) providing a platform with a variable ballast;(b) fastening a flotation device to the platform in a manner to increase buoyancy of the platform, the flotation device causing the platform to float in a towing position with the platform and the flotation device partially submerged; then(c) towing the platform and the flotation device to a desired location; then(d) increasing the ballast of the platform, and unfastening the flotation device so that the platform moves downward relative to the flotation device to a deeper partially submerged but floating position while retaining the flotation device floating adjacent a portion of the platform to provide stability against heeling; then(e) removing the flotation device from a vicinity of the platform while the platform remains floating. 2. The method according to claim 1, wherein step (b) comprises securing the flotation device adjacent a lower base section of the platform: and step (c) comprisestowing the platform to the desired location while the flotation device remains adjacent the lower base section. 3. The method according to claim 1, wherein step (b) comprises rigidly securing the flotation device to the platform; and step (c) comprises towing the platform to the desired location while the flotation device remains rigidly secured to the platform. 4. The method according to claim 1, wherein:step (a) comprises providing the platform with an upper vertically elongated tower section and a lower base section having a horizontal cross-sectional area greater than the tower section;step (b) comprises mounting the flotation device to the lower base section; andstep (c) comprises towing the platform to the desired location while the flotation device remains mounted to the lower base section; andstep (d) comprises releasing the flotation device from the lower base section but retaining the flotation device adjacent the tower section as the platform moves downward. 5. The method according to claim 1, wherein:step (a) comprises providing the platform with an upper vertically elongated tower section and a lower base section having a horizontal cross-sectional area greater than the tower section, and providing the flotation device with a water plan that is greater than a water plan of the tower section;step (b) comprises rigidly mounting at least a portion of the flotation device directly on top of the base section around the tower section;step (c) comprises towing the platform to the desired location while the flotation device remains directly on top of the base section: andstep (d) comprises releasing the flotation device from its position directly on top of the base section but retaining the flotation device around the tower section as the platform moves downward. 6. The method according to claim 1, wherein while in the towing position, the flotation device has a greater water plan than the platform. 7. A method for deploying an offshore well facility, comprising:(a) providing a platform with a variable ballast:(b) fastening a flotation device to the platform in a manner to increase buoyancy of the platform, the flotation device causing the platform to float in a towing position with the platform and the flotation device partially submerged; then(c) towing the platform and the flotation device to a desired location; then(d) increasing the ballast of the platform, and unfastening the flotation device so that the platform moves downward relative to the flotation device to a deeper partially submerged position while retaining the flotation device floating adjacent a portion of the platform to provide stability against heeling; then(e) removing the flotation device from a vicinity of the platform; and whereinstep (a) comprises providing the platform with an upper vertically elongated tower section and a lower base section having a horizontal cross-sectional area greater than the tower section;step (b) comprises forming the fl otation device into an annular configuration with separable segments, and mounting at least a portion of the flotation device on top of the base section and around a lower portion of the tower section;step (d) comprises leaving the flotation device around the tower section as the platform moves downward; andstep (e) comprises separating at least some of the segments from each other and pulling them laterally outward from the tower section. 8. A method for deploying an offshore well facility, comprising:(a) providing a platform with a variable ballast:(b) fastening a flotation device to the platform in a manner to increase buoyancy of the platform, the flotation device causing the platform to float in a towing position with the platform and the flotation device partially submerged; then(c) towing the platform and the flotation device to a desired location; then(d) increasing the ballast of the platform, and unfastening the flotation device so that the platform moves downward relative to the flotation device to a deeper partially submerged position while retaining the flotation device floating adjacent a portion of the platform to provide stability against heeling; then(e) removing the flotation device from a vicinity of the platform; and after the flotation device is disengaged:mounting an upper deck structure on a buoyant member that has two laterally spaced apart arms;floating the arms on opposite sides of an upper portion of the platform, with the deck structure spaced above an upper end of the platform; thenallowing the platform to become less submerged, causing the upper end of the platform to contact and support the deck structure; thenattaching the deck structure to the upper end of the platform and removing the buoyant member. 9. A method for deploying an offshore well facility, comprising:(a) providing a platform with an elongated upper tower section and a lower base section, the base section having a greater horizontal cross-sectional than the tower section;(b) securing a flotation device to the base section at least partially surrounding the tower section, the flotation device causing the platform to float in a towing position with the base fully submerged and the flotation device partially submerged; then(c) towing the platform and the flotation device to a desired location while the flotation device remains secured to the base section; then(d) releasing the flotation device from the base section to allow downward vertical movement of the platform relative to the flotation device while the flotation device remains floating and at least partially surrounding the tower section, and pumping water into a chamber of the platform to cause the platform to move downward relative to the flotation device to a deeper partially submerged but still floating position; then(e) disengaging the flotation device from the tower section while the platform remains floating. 10. A method for deploying an offshore well facility, comprising:(a) providing a platform with an elongated upper tower section and a lower base section, the base section having a greater horizontal cross-sectional than the tower section;(b) securing a flotation device to the base section at least partially surrounding the tower section, the flotation device causing the platform to float in a towing position with the base fully submerged and the flotation device partially submerged; then(c) towing the platform and the flotation device to a desired location; then(d) releasing the flotation device from the base section to allow downward vertical movement of the platform relative to the flotation device while the flotation device remains floating and at least partially surrounding the tower section, and pumping water into a chamber of the platform to cause the platform to move downward relative to the flotation device to a deeper partially submerged position; then(e) disengaging the flotation device from the tower section; andwherein the step of securing the flotation d evice in step (b) comprises completely surrounding the tower section with the flotation device. 11. A method for deploying an offshore well facility, comprising:(a) providing a platform with an elongated upper tower section and a lower base section, the base section having a greater horizontal cross-sectional than the tower section;(b) securing a flotation device to the base section at least partially surrounding the tower section, the flotation device causing the platform to float in a towing position with the base fully submerged and the flotation device partially submerged; then(c) towing the platform and the flotation device to a desired location; then(d) releasing the flotation device from the base section to allow downward vertical movement of the platform relative to the flotation device while the flotation device remains floating and at least partially surrounding the tower section, and pumping water into a chamber of the platform to cause the platform to move downward relative to the flotation device to a deeper partially submerged position; then(e) disengaging the flotation device from the tower section; andwherein the step of securing the flotation device in step (b) comprises completely surrounding a lower portion of the tower section with the flotation device and also surrounding at least an upper portion of the base with the flotation device. 12. A method for deploying an offshore well facility, comprising:(a) providing a platform with an elongated upper tower section and a lower base section, the base section having a greater horizontal cross-sectional than the tower section;(b) securing a flotation device to the base section at least partially surrounding the tower section, the flotation device causing the platform to float in a towing position with the base fully submerged and the flotation device partially submerged; then(c) towing the platform and the flotation device to a desired location; then(d) releasing the flotation device from the base section to allow downward vertical movement of the platform relative to the flotation device while the flotation device remains floating and at least partially surrounding the tower section, and pumping water into a chamber of the platform to cause the platform to move downward relative to the flotation device to a deeper partially submerged position; then(e) disengaging the flotation device from the tower section; and after the flotation device is disengaged:mounting an upper deck structure on a buoyant member that has two laterally spaced apart arms;floating the arms on opposite sides of the tower section, with the deck structure spaced above an upper end of the tower section; thenallowing the platform to become less submerged, causing the upper end of the tower section to move upward and lift the deck structure from the buoyant member; andattaching the deck structure to the upper end of the tower section and removing the buoyant member. 13. An offshore well facility, comprising:a platform having a variable ballast;a flotation device secured and extending around part of the platform while in a towing position, the flotation device and a lower portion of the platform being partially submerged with an upper portion of the platform extending above the flotation device while in the towing position;the flotation device having a deploying position, wherein the ballast of the platform is increased, causing the platform to move downward relative to the flotation device from the towing position to a deeper partially submerged position while the flotation device remains floating and extending around the upper portion of the platform to provide stability against heeling;the flotation device being releasable from the platform once the platform is submerged sufficiently to become stabile; andthe platform having sufficient buoyancy to remain floating after the flotation device is released from the platform. 14. The facility according to claim 13, wherein the flotation device is sec ured to the platform adjacent a bottom of the platform. 15. An offshore well facility, comprising:a platform having a variable ballast;a flotation device secured and extending around part of the platform while in a towing position, the flotation device and a lower portion of the platform being partially submerged with an upper portion of the platform extending above the flotation device while in the towing position;the flotation device having a deploying position, wherein the ballast of the platform is increased, causing the platform to move downward relative to the flotation device from the towing position to a deeper partially submerged position while the flotation device remains floating and extending around the upper portion of the platform to provide stability against heeling;the flotation device being releasable from the platform once the platform is submerged sufficiently to become stabile; andwherein the flotation device is annular and formed of circumferentially extending segments that are separable from each other to release the flotation device from the platform. 16. An offshore well facility, comprising:a platform having a variable ballast;a flotation device secured and extending around part of the platform while in a towing position, the flotation device and a lower portion of the platform being partially submerged with an upper portion of the platform extending above the flotation device while in the towing position;the flotation device having a deploying position, wherein the ballast of the platform is increased, causing the platform to move downward relative to the flotation device from the towing position to a deeper partially submerged position while the flotation device remains floating and extending around the upper portion of the platform to provide stability against heeling;the flotation device being releasable from the platform once the platform is submerged sufficiently to become stabile;an upper deck structure;a buoyant member that has two laterally spaced apart arms, the upper deck structure being carried on the buoyant member while in a towing position;the arms being positionable on opposite sides of the platform, with the deck structure spaced above an upper end of the platform, enabling the ballast of the platform to be decreased to cause the upper end of the platform to move upward to support the deck structure; andthe buoyant member being disengagable from the upper deck structure and the platform. 17. An offshore well facility, comprising:a platform having an upper elongated tower section and a lower base section that has a greater horizontal cross-section than the tower section;a plurality of circumferentially extending segments that secure to each other to define an annular flotation device, the flotation device extending around a lower portion of the tower section on top of the base section while in a towing position, the flotation device being fastened to the platform by a set of fasteners while in the towing position and having sufficient buoyancy to cause the platform to float with base section submerged, the flotation device partially submerged, and an upper portion of the platform extending above the flotation device;the flotation device having a deploying position wherein the fasteners are released, enabling ballast of the platform to be increased, causing the platform to move downward relative to the flotation device from the towing position to a deeper partially submerged position while the flotation device remains floating and extending around the tower section to provide stability against heeling; andat least some of the segments of the flotation device being releasable from each other to enable them to be pulled away from the platform once the platform is submerged sufficiently to stabilize the platform. 18. The facility of claim 17, wherein the each of the segments is separately sealed so as to be independently buoyant. 19. A stabilizing apparatus for use in towing an offshore wel l platform, comprising:a flotation device having a configuration for extending around a portion of the platform;a set of fasteners for rigidly fastening the flotation device to the platform around a bottom portion of the platform while in a towing position with both the platform and the flotation device being partially submerged;the fasteners being releasable to enable the platform to move downward relative to the flotation device at a designated site while the flotation device remains floating and extending around the upper portion of the platform; andthe flotation device being removable from the platform once the platform is submerged sufficiently to stabilize the platform. 20. A stabilizing apparatus for use in towing an offshore well platform, comprising:a flotation device having a configuration for extending around a portion of the platform;a set of fasteners for fastening the flotation device to the platform while in a towing position with both the platform and the flotation device being partially submerged;the fasteners being releasable to enable the platform to move downward relative to the flotation device at a designated site while the flotation device remains floating and extending around the upper portion of the platform;the flotation device being removable from the platform once the platform is submerged sufficiently to stabilize the platform; andwherein the flotation device comprises an annular member. 21. A stabilizing apparatus for use in towing an offshore well platform, comprising:a plurality of segments that secure to each other to define an annular flotation device for extending around a portion of the platform;a set of fasteners for fastening the flotation device to the platform while in a towing position with both the flotation device and the platform being partially submerged and an upper portion of the platform protruding above the flotation device;the fasteners being releasable to enable the platform to move downward relative to the flotation device at a designated site while the flotation device remains floating and extending around the upper portion of the platform; andat least some of the segments of the flotation device being separable from each other to enable them to be pulled away from the upper portion of the platform once the platform is submerged sufficiently to become stabile. 22. The stabilizing apparatus according to claim 21 wherein the flotation device has circular inner and outer diameters. 23. The stabilizing apparatus according to claim 21 wherein the segments comprise watertight chambers that are independently sealed from each other so that each segment is independently buoyant.