Dry-tree semi-submersible production and drilling unit
First Claim
Patent Images
1. A dry-tree semi-submersible production and drilling platform unit, comprising:
- a semi-submersible hull portion, the hull portion including a ring pontoon and at least four columns connected to the ring pontoon;
a mooring portion anchored to a sea floor and mechanically coupled to each of the at least four columns;
a topside portion supported by the hull, the topside portion including a deck box with at least one of a plated bottom and a grated bottom;
a wellbay portion positioned in a central location of the deck box and configured to support a drilling substructure, a production substructure and a plurality of top-tensioned risers, the wellbay portion including a plurality of well slots arranged in a grid pattern, the drilling substructure configured to provide vertical access to each well slot in the grid pattern;
a top-tensioned riser portion including the plurality of top-tensioned risers and at least one of dry-trees and direct vertical access to each of the plurality of well slots;
a catenary riser portion including a plurality of steel catenary or flexible risers, each of the steel catenary or flexible risers being hung from the ring pontoon;
and a riser tensioning subsystem having a plurality of riser tensioners configured to provide vertical motion compensation for each of the plurality of top-tensioned risers, wherein the riser tensioning subsystem is characterized by a tension level parameter, a stroke length parameter, and a stiffness parameter, andwherein a set of values for the tension level parameter, the stroke length parameter, and the stiffness parameter is determined based on a field water depth, a number of wells in the wellbay portion, a predetermined top-tensioned riser configuration, and a predetermined topside capacity,wherein the tension level parameter, the stroke length parameter, the stiffness parameter, and a number of top-tensioned risers are determined such that an effective total stiffness of the riser tensioning subsystem is maintained within a range of between 10% and 30% of a platform water plane stiffness at in-place operating conditions.
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Abstract
A deep draft semi-submersible production and drilling platform unit with dry trees is described. The platform unit preferably comprises four columns, a ring pontoon, a two-axis symmetrical hull with draft in the range of 100 to 155 feet, top-tensioned risers with push or pull tensioners of preferred combined vertical stiffness of 10% to 30% of the platform water plane stiffness, a wellbay with a well spacing in the range of 12 to 18 feet, a riser guiding system supported by the pontoons or at an elevated level, topside facilities supported by a box type of deck structure, mooring lines, and catenary risers.
19 Citations
20 Claims
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1. A dry-tree semi-submersible production and drilling platform unit, comprising:
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a semi-submersible hull portion, the hull portion including a ring pontoon and at least four columns connected to the ring pontoon; a mooring portion anchored to a sea floor and mechanically coupled to each of the at least four columns; a topside portion supported by the hull, the topside portion including a deck box with at least one of a plated bottom and a grated bottom; a wellbay portion positioned in a central location of the deck box and configured to support a drilling substructure, a production substructure and a plurality of top-tensioned risers, the wellbay portion including a plurality of well slots arranged in a grid pattern, the drilling substructure configured to provide vertical access to each well slot in the grid pattern; a top-tensioned riser portion including the plurality of top-tensioned risers and at least one of dry-trees and direct vertical access to each of the plurality of well slots; a catenary riser portion including a plurality of steel catenary or flexible risers, each of the steel catenary or flexible risers being hung from the ring pontoon; and a riser tensioning subsystem having a plurality of riser tensioners configured to provide vertical motion compensation for each of the plurality of top-tensioned risers, wherein the riser tensioning subsystem is characterized by a tension level parameter, a stroke length parameter, and a stiffness parameter, and wherein a set of values for the tension level parameter, the stroke length parameter, and the stiffness parameter is determined based on a field water depth, a number of wells in the wellbay portion, a predetermined top-tensioned riser configuration, and a predetermined topside capacity, wherein the tension level parameter, the stroke length parameter, the stiffness parameter, and a number of top-tensioned risers are determined such that an effective total stiffness of the riser tensioning subsystem is maintained within a range of between 10% and 30% of a platform water plane stiffness at in-place operating conditions. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A dry-tree semi-submersible production and drilling platform unit, comprising:
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a semi-submersible hull portion, the hull portion including a ring pontoon and at least four columns connected to the ring pontoon; a mooring portion anchored to a sea floor and mechanically coupled to each of the at least four columns; a topside portion supported by the hull, the topside portion including a deck box with at least one of a plated bottom and a grated bottom; a wellbay portion positioned in a central location of the deck box and configured to support a drilling substructure, a production substructure and a plurality of top-tensioned risers, the wellbay portion including a plurality of well slots arranged in a grid pattern, the drilling substructure configured to provide vertical access to each well slot in the grid pattern; a top-tensioned riser portion including the plurality of top-tensioned risers and at least one of dry-trees and direct vertical access to each of the plurality of well slots; a catenary riser portion including a plurality of steel catenary or flexible risers, each of the steel catenary or flexible risers being hung from the ring pontoon; and a riser tensioning subsystem having a plurality of riser tensioners configured to provide vertical motion compensation for each of the plurality of top-tensioned risers, wherein the riser tensioning subsystem is characterized by a tension level parameter, a stroke length parameter, and a stiffness parameter, and wherein a set of values for the tension level parameter, the stroke length parameter, and the stiffness parameter is determined based on a field water depth, a number of wells in the wellbay portion, a predetermined top-tensioned riser configuration, and a predetermined topside capacity, wherein the hull portion is configured to suppress platform heave motions to enhance riser performance while maintaining a predetermined hull portion maximum height for quayside integration of the topside portion with the hull portion. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. A dry-tree semi-submersible production and drilling platform unit, comprising:
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a semi-submersible hull portion, the hull portion including a ring pontoon and at least four columns connected to the ring pontoon; a mooring portion anchored to a sea floor and mechanically coupled to each of the at least four columns; a topside portion supported by the hull, the topside portion including a deck box with at least one of a plated bottom and a grated bottom; a wellbay portion positioned in a central location of the deck box and configured to support a drilling substructure, a production substructure and a plurality of top-tensioned risers, the wellbay portion including a plurality of well slots arranged in a grid pattern, the drilling substructure configured to provide vertical access to each well slot in the grid pattern; a top-tensioned riser portion including the plurality of top-tensioned risers and at least one of dry-trees and direct vertical access to each of the plurality of well slots; a catenary riser portion including a plurality of steel catenary or flexible risers, each of the steel catenary or flexible risers being hung from the ring pontoon; and a riser tensioning subsystem having a plurality of riser tensioners configured to provide vertical motion compensation for each of the plurality of top-tensioned risers, wherein the riser tensioning subsystem is characterized by a tension level parameter, a stroke length parameter, and a stiffness parameter, and wherein a set of values for the tension level parameter, the stroke length parameter, and the stiffness parameter is determined based on a field water depth, a number of wells in the wellbay portion, a predetermined top-tensioned riser configuration, and a predetermined topside capacity, wherein the platform unit is configured such that a heave natural period of the platform unit is maintained within a range of between 5 seconds and 8 seconds longer than a peak period of a predetermined governing design storm with all risers installed.
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20. A dry-tree semi-submersible production and drilling platform unit, comprising:
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a semi-submersible hull portion, the hull portion including a ring pontoon and at least four columns connected to the ring pontoon; a mooring portion anchored to a sea floor and mechanically coupled to each of the at least four columns; a topside portion supported by the hull, the topside portion including a deck box with at least one of a plated bottom and a grated bottom; a wellbay portion positioned in a central location of the deck box and configured to support a drilling substructure, a production substructure and a plurality of top-tensioned risers, the wellbay portion including a plurality of well slots arranged in a grid pattern, the drilling substructure configured to provide vertical access to each well slot in the grid pattern; a top-tensioned riser portion including the plurality of top-tensioned risers and at least one of dry-trees and direct vertical access to each of the plurality of well slots; a catenary riser portion including a plurality of steel catenary or flexible risers, each of the steel catenary or flexible risers being hung from the ring pontoon; and a riser tensioning subsystem having a plurality of riser tensioners configured to provide vertical motion compensation for each of the plurality of top-tensioned risers, wherein the riser tensioning subsystem is characterized by a tension level parameter, a stroke length parameter, and a stiffness parameter, and wherein a set of values for the tension level parameter, the stroke length parameter, and the stiffness parameter is determined based on a field water depth, a number of wells in the wellbay portion, a predetermined top-tensioned riser configuration, and a predetermined topside capacity, wherein a configuration of the mooring portion is based on a nominal stroke position of each of the plurality of riser tensioners, the respective nominal stroke positions being determined in accordance with a predetermined maximum up stroke and a predetermined maximum down stroke relating to each of a normal operational mode, an extreme storm mode, and a survival mode.
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Specification