MULTI-USE OFFSHORE STRUCTURE

Abstract

Described is a multi-use offshore structure having a first configuration and a second configuration. The first configuration includes a pontoon base disposed at a lower end of the multi-use offshore structure. A deck is disposed at an upper end of the multi-use offshore structure, and hull column structures extend between the pontoon base and the deck. The second configuration includes the pontoon base, the deck, and the hull column structures of the first configuration. A set of sponsons is formed to be installed on the hull column structures, and a deck expansion unit is connectable with the deck.

Claims

1. A multi-use offshore structure, comprising: a multi-use offshore structure having a first configuration and a second configuration, the first configuration comprising: a pontoon base disposed at a lower end of the multi-use offshore structure, the pontoon base having a top surface and a bottom surface; a deck disposed at an upper end of the multi-use offshore structure; and a plurality of hull column structures extending between the pontoon base and the deck, each hull column structure having a top end and a bottom end; the second configuration comprising: the pontoon base, the deck, and the plurality of hull column structures of the first configuration, and a set of sponsons, each sponson formed to be installed on one hull column structure of the plurality of hull column structures, wherein each of the plurality of hull column structures is designed to receive a sponson; and a deck expansion unit connectable with the deck.

2. The multi-use offshore structure of claim 1, wherein the first configuration has a first deck capacity and the second configuration has a second deck capacity, wherein the second deck capacity is greater than the first deck capacity.

3. The multi-use offshore structure of claim 1, comprising one or more sponson connections attached with a hull column structure, wherein each sponson comprises at least one connection element for attaching with a sponson connection.

4. The multi-use offshore structure of claim 3, wherein at least one sponson is formed to be ballasted.

5. The multi-use offshore structure of claim 1, wherein each sponson is installed on a hull column structure such that a bottom end of each sponson is substantially aligned with the bottom surface of the pontoon base.

6. The multi-use offshore structure of claim 1, wherein each sponson is installed on a hull column structure such that a top end of each sponson is substantially aligned with the top end of the hull column structure.

7. The multi-use offshore structure of claim 1, wherein each sponson is configured to be removably installed on a hull column structure.

8. The multi-use offshore structure of claim 1, wherein the deck expansion unit is configured to be detachably attached with the deck in the second configuration.

9. The multi-use offshore structure of claim 8, comprising at least one module formed to be installed on the deck expansion unit in the second configuration.

10. A method for forming a multi-use offshore structure, comprising: designing the multi-use offshore structure to be expandable from a first configuration to a second configuration, the first configuration comprising: a pontoon base disposed at a lower end of the multi-use offshore structure, the pontoon base having a top surface and a bottom surface; a deck disposed at an upper end of the multi-use offshore structure; and a plurality of hull column structures extending between the pontoon base and the deck, each hull column structure having a top end and a bottom end; the second configuration comprising: the pontoon base, the deck, and the plurality of hull column structures of the first configuration; and a set of sponsons; the method further comprising: installing the set of sponsons on the multi-use offshore structure while in the first configuration, wherein each sponson is installed on one hull column structure of the plurality of hull column structures; and connecting a deck expansion unit to the deck, forming the second configuration.

11. The method of claim 10, wherein the designing comprises: determining a target increase in deck capacity for the second configuration; and based on a plurality of calculated parameters, forming the set of sponsons and deck expansion unit to meet the target increase in deck capacity.

12. The method of claim 11, wherein the plurality of calculated parameters comprises one or more of weight, length, width, mooring size, airgap, heave, roll, pitch, and riser porch vertical velocity.

13. The method of claim 10, wherein the first configuration has a first deck capacity and the second configuration has a second deck capacity, wherein the second deck capacity is greater than the first deck capacity.

14. The method of claim 10, further comprising attaching each sponson to a hull column structure via a sponson connection.

15. The method of claim 14, further comprising ballasting at least one sponson.

16. The method of claim 10, wherein connecting the deck expansion unit to the deck comprises lifting the deck expansion unit to the deck utilizing one or more cranes installed on the multi-use offshore structure.

17. The method of claim 10, wherein each sponson is installed on one of the hull column structures of the plurality of hull column structures such that a bottom end of each sponson is substantially aligned with the bottom surface of the pontoon base.

18. The method of claim 10, wherein each sponson is installed on one of the hull column structures of the plurality of hull column structures such that a top end of each sponson is substantially aligned with the top end of the hull column structure.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0025] FIG. 1 is an illustration of a semi-submersible used in a typical offshore environment.

[0026] FIG. 2A is an illustration of a convertible semi-submersible with permanent sponsons according to one or more embodiments of the present disclosure.

[0027] FIG. 2B is an illustration of a submerged convertible semi-submersible with permanent sponsons according to one or more embodiments of the present disclosure.

[0028] FIG. 3A is a perspective-view illustration of a sponson and sponson connections according to one or more embodiments of the present disclosure.

[0029] FIG. 3B is a side-view illustration of a sponson and sponson connection according to one or more embodiments of the present disclosure.

[0030] FIG. 4A is a perspective-view illustration of frame structures connected with a sponson according to one or more embodiments of the present disclosure.

[0031] FIG. 4B is a top-view illustration of a frame structure connected with a sponson according to one or more embodiments of the present disclosure.

[0032] FIG. 4C is a perspective-view illustration of frame structures connected with a sponson according to one or more embodiments of the present disclosure.

[0033] FIGS. 5A-5B show examples of sponson connections according to one or more embodiments of the present disclosure.

[0034] FIGS. 6A-6D show examples of attachment mechanisms for sponsons according to one or more embodiments of the present disclosure.

DETAILED DESCRIPTION

[0035] In the following detailed description of embodiments of the disclosure, numerous specific details are set forth in order to provide a more thorough understanding of the disclosure. However, it will be apparent to one of ordinary skill in the art that the disclosure may be practiced without these specific details. In other instances, well-known features have not been described in detail to avoid unnecessarily complicating the description.

[0036] Throughout the application, ordinal numbers (e.g., first, second, third, etc.) may be used as an adjective for an element (i.e., any noun in the application). The use of ordinal numbers is not to imply or create any particular ordering of the elements nor to limit any element to being only a single element unless expressly disclosed, such as using the terms before, after, single, and other such terminology. Rather, the use of ordinal numbers is to distinguish between the elements. By way of an example, a first element is distinct from a second element, and the first element may encompass more than one element and succeed (or precede) the second element in an ordering of elements.

[0037] In the following description of FIGS. 2A-6D, any component described with regard to a figure, in various embodiments disclosed herein, may be equivalent to one or more like-named components described with regard to any other figure. For brevity, descriptions of these components will not be repeated with regard to each figure. Thus, each and every embodiment of the components of each figure is incorporated by reference and assumed to be optionally present within every other figure having one or more like-named components. Additionally, in accordance with various embodiments disclosed herein, any description of the components of a figure is to be interpreted as an optional embodiment which may be implemented in addition to, in conjunction with, or in place of the embodiments described with regard to a corresponding like-named component in any other figure.

[0038] It is to be understood that the singular forms a, an, and the include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to a passive soil gas sample system includes reference to one or more of such systems.

[0039] Terms such as approximately, substantially, etc., mean that the recited characteristic, parameter, or value need not be achieved exactly, but that deviations or variations, including for example, tolerances, measurement error, measurement accuracy limitations and other factors known to those of skill in the art, may occur in amounts that do not preclude the effect the characteristic was intended to provide.

[0040] It is to be understood that one or more of the steps described herein may be omitted, repeated, and/or performed in a different order. Accordingly, the scope disclosed herein should not be considered limited to the specific arrangement of steps described herein.

[0041] In one aspect, embodiments disclosed herein generally relate to an offshore structure. More specifically, embodiments disclosed herein relate to a multi-use offshore structure. The multi-use offshore structure may be in any marine environment without departing from the scope of the present disclosure. In one aspect, embodiments disclosed herein relate to a multi-use offshore structure having a first configuration designed to be able to be converted, or expandable, to a second configuration having an increased load capacity in the future. As used herein, an increased load capacity may refer to an increase in the load capacity of the multiuse offshore structure's deck, including an increase in the amount of weight the deck may hold (topside weight increase) and/or an increase in the amount of deck area. An increased load capacity of a deck may be provided by effectively increasing the volume of hull column structures according to embodiments of the present disclosure.

[0042] In order to carry maximum cargo during an initial transit to an offshore site, some semi-submersible structures require additional stability capacity. As used herein, stability capacity may refer to hull column volume, where an increase in hull column volume may provide increased stability. For instance, in addition to an increase in topside weight and deck area, hull column volume, and therefore buoyancy of the structure, may also be increased in the second configuration. According to one or more embodiments of the present disclosure, the increased stability capacity may be obtained through the implementation of temporary sponsons, which enable a larger deck weight to be carried during transit and transition to a final operating configuration. Temporary sponsons may be used to maintain stability of the multi-use offshore structure with sufficient metacentric height during transit and transition phases of installation. Support structures for securing temporary sponsons may be attached with the hull of the multi-use offshore structure. The support structures may be used to secure temporary sponsons, which enable initial transit and transition, or permanent sponsons, which increase the operating capacity of the multi-use offshore structure. After transitioning to a sufficiently deep draft in open water, the temporary sponsons may be removed or replaced with permanent sponsons. Each of these aspects will be described in detail below.

[0043] Referring to FIGS. 2A and 2B, a multi-use offshore structure 200 in accordance with one or more embodiments of the present disclosure is shown. Similar to the typical offshore structure depicted in FIG. 1, the multi-use offshore structure 200 comprises a deck 202 disposed at an upper end of the multi-use offshore structure 200 and a plurality of hull column structures 204a-204d, which act as support columns to support the deck 202. Each hull column structure (e.g., 204a) has a top end, a bottom end, and any number of sides or faces. As a non-limiting example, each hull column structure (e.g., 204a) is generally cylindrical with a circular cross-section. Alternatively, each hull column structure may have more than one side with a two-dimensional cross-section that is semi-circular, triangular, quadrangular, or any other suitable shape. To provide structural integrity, hull column structures may have outer wall(s) made of high-strength materials designed to withstand harsh marine conditions, hydrostatic pressure, and/or dynamic loads, such as steel, and in some embodiments may be reinforced. To provide buoyancy, the hull column structures may be hollow or contain compartments within the outer wall(s), which may store fluid ballast material (e.g., seawater), fuel, and/or other fluids. In one or more embodiments, the amount of fluid stored in hull column structures may be adjusted, e.g., using one or more fluidly connected valve(s) and pump(s) to direct fluid into/out of the column to adjust the buoyancy of the columns.

[0044] A pontoon base 206, having a top surface and a bottom surface, may be disposed at a lower end of the multi-use offshore structure 200 to support the hull column structures 204a-204d, such that the hull column structures 204a-204d extend between the pontoon base 206 and the deck 202. The pontoon base 206 may include one or more connected pontoons. For example, in a polygonal-shaped pontoon base, each side of the polygon may be formed of a pontoon having an elongated hollow body, where the axial ends of each pontoon are connected to form the corners of the polygonal pontoon base. Each pontoon may be filled with ballast material (e.g., seawater, drilling fluid, sand, or a heavier solid ballast material to help lower the center of gravity, such as concrete). In addition, a portion, or all, of the pontoon base 206 may be underwater, as depicted in FIG. 2B.

[0045] The pontoon base 206 may be generally rectangular, triangular, and/or polygonal in shape and the hull column structures 204a-204d may be disposed near the corners of or at any position along the pontoon base 206. One of ordinary skill in the art would appreciate that the positions of the hull column structures 204a-204d are not limited to the corners of the pontoon base 206, as the hull column structures 204-204d may be arranged in any other configuration with respect to the pontoon base 206. In addition, one of ordinary skill in the art would know and appreciate that the number of hull column structures is not limited to four hull column structures 204a-204d, as shown, as there may be any number of hull column structures. As shown in FIG. 2B, a portion of one or more of the hull column structures 204a-204d may also be underwater.

[0046] In one or more embodiments, the multi-use offshore structure 200 comprises a deck expansion unit 208 which is connectable with the deck 202, or another portion of the multi-use offshore structure 200 in any suitable manner, to increase the deck's load capacity, thereby producing a second configuration. In one or more embodiments, a deck expansion unit 208 may include a plurality of support members, which may be connected to each other and connected to the existing deck 202 to provide an increased surface area of the deck. In some embodiments, support members of a deck expansion unit may have the same configuration (e.g., elongated beams or tubular members) and/or may be formed of the same material as support members forming the existing deck 202. The deck expansion unit 208 may be lifted to the deck 202 via one or more cranes 209 installed on the multi-use offshore structure 200. The deck expansion unit 208 may be used to support a portion and/or an expansion of the deck 202 or may support any other equipment known in the art. For example, should it be determined that additional support is necessary for rig expansion or otherwise, the deck expansion unit 208 may be attached to increase the load capacity of the deck 202 and, ultimately, allow for additional modules, such as equipment or structures (represented by 210), to be added or installed to the multi-use offshore structure 200. For example, for a production platform, a chemical injection module or a seawater injection module may be added to accommodate for changes in production operations. A deck's load capacity may be quantified, for example, by the total weight that can be supported by the deck without failure of the deck. In one or more embodiments, the deck's load capacity is quantified by the payload the deck can carry (e.g., measured in weight tonnage) without failure.

[0047] According to one or more embodiments of the present disclosure, the additional load capacity for the multi-use offshore structure 200 may be obtained by introducing temporary sponsons (or pencil columns), enabling a larger deck weight to be carried during transit and transition to the final operating draft. Sponsons may be used to maintain the stability of the multi-use offshore structure 200. The sponsons may be considered as either temporary, to enable initial transit and transition, or permanent (such as shown in FIGS. 2A and 2B), to increase the load capacity of the multi-use offshore structure 200, which may allow for more equipment to be carried on the deck, and which may therefore, allow for increased operations (increased operating capacity). After transitioning to a sufficiently deep draft, temporary sponsons (not shown) may be removed. Therefore, the hull column structures 204a-204d may be designed to support temporary sponsons, which may then be later replaced with permanent sponsons 212a-212c that provide additional stability and load capacities for the multi-use offshore structure 200 when upgrades become necessary to maintain or increase production levels. Temporary sponsons may be used for a short period of time during transport, modification/repair, and/or during certain operating scenarios.

[0048] One or more, temporary or permanent, sponsons (e.g., 212a) may be installed on a given hull column structure (e.g., 204a). For example, as described in more detail below, a sponson may be mounted to a hull column structure via a frame structure and/or sponson connections. Permanent sponsons 212a-212c may be designed to have larger volume capacities (e.g., longer and/or larger) than temporary sponsons. For example, in one or more embodiments, permanent sponsons 212a-212c may have the same diameter as temporary sponsons, but longer lengths than temporary sponsons. The permanent sponsons may be positioned along respective hull column structures 204a-c, such that the length of the permanent sponsons 212a-212c may extend parallel with the length of the hull column structures to the top of the hull column structures. The diameter of a temporary sponson may be between 10 feet and 20 feet, such as 14 feet. In general, the permanent sponsons may be longer and larger in diameter than the temporary sponsons. As a non-limiting example, a permanent sponson (e.g., 212a) may weigh a total of about 1040 tons with a length of about 135 feet. The weight of a frame structure supporting a sponson (described below) may be about 208 tons, and the additional load capacity attained by the permanent sponson(s) may be about 1000 tons at approximately 225 feet above baseline (ABL). The increase in additional deck load capacity with the use of permanent sponsons compared to temporary sponsons may be approximately 1000 tons of payload increase. In one or more embodiments, temporary sponsons may be replaced with permanent sponsons on a multi-use offshore structure to increase its deck load capacity by between 900 to 1100 tons (compared to the deck's load capacity with only temporary sponsons).

[0049] FIGS. 3A and 3B show perspective and side views, respectively, of two exemplary sponson connections for temporary sponson 212, an upper sponson connection 300a and lower sponson connection 300b, which are designed to connect the sponson 212 to a hull column structure (partially shown by 314). Sponson connections may be integrally formed with a hull column structure or attached to a hull column structure, e.g., by welding. In one or more embodiments, the sponson connections 300a and 300b may be provided at selected axial locations along one side of a hull column structure, such that a sponson may be connected along the side of the hull column structure in a longitudinal orientation substantially parallel with the hull column structure. The sponson 212 may be connected with the sponson connections 300a and 300b via frame structures 302a, 302b. The frame structures 302a, 302b may be integrally formed with or connected (e.g., welded) to the sponson 212. FIGS. 4A-4C show examples of sponsons 212 and connected frame structures 302a, 302b prior to engagement with the sponson connections.

[0050] FIGS. 5A and 5B show the upper sponson connection 300a and lower sponson connection 300b, respectively, in more detail. In one or more embodiments, the upper sponson connection 300a and the lower sponson connection 300b each include a compartment 304a and 304b, respectively. The compartments 304a, 304b may be fluidly connected with a compartment in the main body of the hull column structure. Compartments in hull column structures (e.g., compartments 304a, 304b, and/or compartments in the main body of a hull column structure) and compartments provided in sponsons may be watertight, buoyant compartments, enabling floating self-transportation of the sponsons in a stable, vertical condition. Compartment(s) in sponsons may be defined by the sponson wall and/or internal housings made of the same materials as the hull column structures. Connecting ends 301 may be provided at opposite ends of each sponson connection 300a, 300b for connecting the sponson connections 300a, 300b to the frame structures 302a, 302b shown in FIGS. 4A and 4B.

[0051] In one or more embodiments, connecting ends 301 of sponson connections may be formed by a plate of high-strength material such as steel having a cut-out 303, or receiving portion, which may be shaped to receive and bear a tubular component 400 of a frame structure 302a, 302b. For example, in FIG. 5A, the upper sponson connection 300a may have connecting ends 301 each with a cut-out 303 opening to a side 306 of the connecting end opposite from the first compartment 304a, where the cut-out 303 may have a size and shape that corresponds with and/or fits around a connecting component (e.g., tubular component 400) of the frame structure 302a. The upper sponson connection 300a may extend horizontally along a hull column structure and receive a corresponding horizontally oriented component (e.g., tubular component 400) of a frame structure 302a. With such configuration, the frame structure 302a may be mounted horizontally to the upper sponson connection 300a. As shown in FIG. 5B, the lower sponson connection 300b may have connecting ends 301 each with a cut-out 303 opening to a bottom side 305 of the connecting end 301, where the cut-out 303 may have a size and shape that corresponds with and/or fits around a connecting component (e.g., tubular component 400) of the frame structure 302b. The lower sponson connection 300b may extend horizontally along a hull column structure and receive a corresponding horizontally oriented component (e.g., tubular component 400) of a frame structure 302b. With such configuration, the frame structure 302b may be mounted vertically to the lower sponson connection 300b.

[0052] FIGS. 4A-C depict perspective and top view illustrations of examples of frame structures 302a and 302b. As shown, the frame structures 302a and 302b may include a tubular component 400 having a desired diameter and length to connect with a given sponson connection. After installing a frame structure (e.g., 302a) on the sponson 212 (or integrally forming a frame structure with a sponson), the sponson 212 may be attached with the hull column structure via the frame structures (e.g., 302a) and sponson connections (e.g., 300a) provided along the hull column structure. For example, as shown in FIGS. 3A-B, receiving portions of sponson connections (e.g., the cut-outs 303 formed in the sponson connection connecting ends 301) may be fitted around the tubular components 400 of the frame structures 302a, 302b to connect the sponsons to the hull column structures.

[0053] In the examples shown in FIGS. 4A-C, frame structures may include one or more horizontal frame members extending along a plane perpendicular to the longitudinal axis of the sponson and one or more angled frame members extending along a plane acutely angled with the perpendicular plane and with the longitudinal axis, such that the horizontal frame member(s) and the angled frame member(s) join together via the tubular component 400. In the example shown in FIGS. 4A-B, both upper and lower frame structures 302a, 302b are in the same orientation and configuration, where the horizontal frame member(s) form the base of the frame structure. In the example shown in FIG. 4C, the upper frame structure 302a orientation and configuration may be mirrored with the lower frame structure 302b configuration, such that the upper frame structure's angled member(s) form the base of the frame structure, while the lower frame structure's horizontal member(s) form the base of the frame structure.

[0054] As would be appreciated by one skilled in the art, the multi-use offshore structure is not limited to two sponson connections per hull column structure; more or less than two sponson connections may be utilized. While illustrated as such, the first compartment 304a configuration is not intended to be limited to the upper frame structure 302a position, and the second compartment 304b configuration is not intended to be limited to the lower frame structure 302b position. Further, while examples shown in the figures show sponsons connected to hull column structures in a 1:1 ratio, other embodiments may include other sponson to hull column structure ratios, e.g., two sponsons connected to one hull column structure.

[0055] According to one or more embodiments of this disclosure, different types of attachment mechanisms may be used to connect a sponson frame structure to a hull column structure sponson connection, as depicted in FIGS. 6A-6D. In one or more embodiments, attachment mechanisms may be connected to and/or formed integrally with a frame structure. In one or more embodiments, attachment mechanisms may be connected to and/or formed integrally with a sponson connection. In one or more embodiments, attachment mechanisms may be provided separately from but connected to both the frame structure and the sponson connection.

[0056] As shown in FIGS. 6A and 6B, clamps 600 may be pivotably connected to a sponson connection 300a of a hull column structure, and may be locked in a closed configuration to cover a front opening of a receiving portion of the sponson connection 300a using a vertical pin 602. When a connection to a temporary sponson via the clamps 600 needs to be removed, the vertical pin 602 may be removed to release the clamp 600. Thereafter, a tugboat may be used to gently pull the temporary sponson so that the frame structure's tubular component 400 slides out. With connections having a downwardly oriented receiving portion (e.g., 303 in FIG. 5B), gravity may provide a net force downward to automatically slide a frame structure's tubular member out of the sponson connection 300a to complete the sponson removal. The sponsons may be installed pre-ballasted or empty. If empty, a sponson may be flooded from its bottom to facilitate the removal process at the offshore site.

[0057] FIG. 6C depicts another embodiment for connecting a sponson's frame structure to a sponson connection via a latch mechanism. In this embodiment, a latch 604 is connected with the sponson connection 300a via a hinge 606. The hinged latch 604 may open to allow insertion or release of the tubular component 400 of the frame structure attached with a sponson. Closing the hinged latch 604 secures the tubular component 400 to the sponson connection 300a, and thus the hull column structure. Alternatively, a sponson's frame structure may be connected to a sponson connection via a pin attachment mechanism, as shown in FIG. 6D. In this embodiment, a plurality of pins 602 (e.g., two pins) extend through a top and bottom side of the sponson connection 300a. Following insertion of the tubular component 400 within the receiving portion of the sponson connection 300a, the pins 602 may be inserted through aligned openings (or holes) within the sponson connection 300a. The pins 602 secure the tubular component 400 into its proper position within the sponson connection 300a, thereby securing the sponson to the hull column structure.

[0058] Embodiments of this disclosure may further include determining a target increase in deck capacity for the second configuration. For instance, based on a plurality of calculated parameters related to components of the multi-use offshore structure, one or more of the temporary sponsons, permanent sponsons, deck, deck expansion unit, frame structures, and any connecting elements may be designed to meet the target increase, such as 1000 megatonnes (MT), in deck capacity. Non-limiting examples of parameters that may be calculated and adjusted include weight, length, width, mooring size, airgap, heave, roll, pitch, and riser porch vertical velocity.

[0059] Requiring additional deck capacity at an offshore structure is a recurring problem. The multi-use offshore structure according to embodiments of this disclosure is designed to be converted from a first configuration having an initial deck load capacity to a second configuration with a deck load capacity greater than the initial deck load capacity. Designing and installing support structures that accommodate both temporary sponsons as well as larger, permanent sponsons provides a cost-effective and time-efficient method for increasing the operating capacity of the multi-use offshore structure.

[0060] Although only a few example embodiments have been described in detail above, those skilled in the art will readily appreciate that many modifications are possible in the example embodiments without materially departing from this invention. Accordingly, all such modifications are intended to be included within the scope of this disclosure as defined in the following claims. Further, although multiple dependent claims are not introduced, it would be apparent to one of ordinary skill that the subject matter of the dependent claims of one or more embodiments may be combined with other dependent claims.