WATERBORNE STRUCTURE FOR SUPPORTING OFFSHORE ACTIVITIES

BACKGROUND

1. Technical Field

[0001]Embodiments described herein generally relate to waterborne structures that utilize cost efficient designs, provide ample enclosed and topside spaces, and are stable over a range of marine conditions.

2. Description of the Related Art

[0002]Activities performed offshore often require a platform suitable for supporting equipment, storing material, providing working and living quarters for personnel, etc. Offshore platforms may be either floating or fixed to a subsea structure. A variety of different configurations have been used for such platforms; e.g., some platforms float while others are fixed to a seabed. Depending on the design, platforms may be referred to as drill ships, semi-submersibles, submersibles, jack-ups, pile jackets, etc. A common drawback of conventional platforms is reliance on complex marine architectures and design features, which can incur significant fabrication costs and require specialized manufacturing techniques. The present disclosure addresses the need for offshore platforms can be fabricated at lower costs using less complex manufacturing techniques.

SUMMARY

[0003]In aspects, the present disclosure provides an offshore platform for use on a body of water. The offshore platform may include a hull having a vertical axis, a flared section, a lower deck section, a ballast system, and at least one enclosed deck. The flared section may be formed by a set of inclined planar walls and a first set of chamfers having inclined planar chamfer walls. The inclined planar walls and the first set of chamfers form a first perimeter defining a boundary between an interior and an exterior of the hull. The first perimeter has an octagonal shape along a plane transverse to the vertical axis. The lower deck section is below the flared section and may be formed by a set of vertical planar walls and a second set of chamfers having vertical planar chamfer walls. The vertical planar walls and the second set of chamfers form a second perimeter defining a boundary between an interior and an exterior of the hull. The second perimeter has an octagonal shape along a plane transverse to the vertical axis. The ballast system has at least one compartment positioned within at least the second perimeter, and a fluid mover configured to control a flow of water between the at least one compartment and the exterior of the hull. The at least one enclosed deck is positioned inside the hull. The at least one compartment separates the at least one enclosed deck and at least the second perimeter.

[0004]In further aspects, the present disclosure provides an offshore platform having a hull, a ballast system, and at least one enclosed deck. The hull has a vertical axis and at least one perimeter defining a boundary between an interior and an exterior of the hull. The hull includes at least one set of planar walls that are symmetrically disposed about the vertical axis. The at least one set of planar walls at least partially define a rectilinear shape for the at least one perimeter. The planar walls have substantially the same width dimension. The ballast system has at least one compartment positioned within the at least one perimeter and a fluid mover configured to control a flow of water between the at least one compartment and the exterior of the hull. The at least one enclosed deck is positioned inside the hull. The at least one compartment separates the at least one enclosed deck and the at least one perimeter.

[0005]It should be understood that examples of certain features of the disclosure have been summarized rather broadly in order that the detailed description thereof that follows may be better understood, and in order that the contributions to the art may be appreciated. There are, of course, additional features of the disclosure that will be described hereinafter and which will in some cases form the subject of the claims appended thereto.

BRIEF DESCRIPTION OF THE DRAWINGS

[0006]For detailed understanding of the present disclosure, references should be made to the following detailed description of the preferred embodiment, taken in conjunction with the accompanying drawings, in which like elements have been given like numerals and wherein:

[0007]FIG. 1 schematically illustrates an embodiment of an offshore platform according to the present disclosure;

[0008]FIG. 2 depicts a plan view of the FIG. 1 offshore platform;

[0009]FIG. 3 depicts a ballast system for the FIG. 1 offshore platform; and

[0010]FIGS. 4A-B schematically illustrate various embodiments and uses of offshore platforms according to the present disclosure.

DETAILED DESCRIPTION

[0011]In certain aspects, the present disclosure provides a floating offshore structure suitable for locations where the water depth is greater than about 60 meters and less than about 2500 meters. As will become apparent from the discussion below, offshore platforms according to the present disclosure employ design configurations that, as compared to conventional offshore platforms, enable the use of relatively simpler manufacturing techniques and more commonly available construction facilities.

[0012]Referring to FIG. 1, there is shown, there is schematically illustrated one non-limiting embodiment of an offshore platform 100 according to the present disclosure. The offshore platform 100 may be deployed on a body of water 10 having a depth between approximately 60 meters and 2500 meters. The offshore platform 100 may be held stationary using a mooring system 102 that connects the offshore platform 100 to a subsea structure, such a seabed 12. In this arrangement, the offshore platform 100 includes a hull 110 and a topsides 112.

[0013]The topsides 112 is positioned completely above the splash zone and may include an open weather deck 130. The weather deck 130 may include a helipad, one or more cranes, HVAC plant rooms, power generation equipment, a bunker station, and a laydown area. In some embodiments, the topsides 112 may be modular. For example, the hull 110 may be configured to receive two or more structurally interchangeable modular topsides that have different configurations.

[0014]The hull 110 is a water-tight, enclosing structure for the platform 100. In one arrangement, the hull 110 includes an upper flared section 114, which is completely above water, and a lower deck section 116, which is partially submerged in water. The flared section 114 is formed by a plurality of inclined planar walls 122 and the lower deck section 116 is formed by a plurality of vertical planar walls 124. As herein, the term “inclined” means an angular deviation from a purely vertical alignment. By inclining the planar walls 122 to extend outward on all sides from the lower deck section 116, the upper flared section 114 has increased width and length relative to the lower deck section 116. By “planar,” it is meant that the majority of the walls are flat and do not incorporate curves.

[0015]The hull 110 may include enclosed decks configured as needed to support any number of activities. These decks are collectively referred to with numeral 120. By way of a non-limiting example, the platform 100 may be configured as discussed below to support electrical power generation by offshore wind turbines.

[0016]In embodiments, the decks 120 are protected from the elements and outside environment. Therefore, the decks 120 are suitable for housing valve halls, HVAC rooms, living quarters, housing shunt reactors, converters, transformers, and other equipment to control the generation and transmission of electrical power. Suitable hatches and openings may be provided to allow the movement of personnel, equipment, materials, and supplies between and throughout the decks 120.

[0017]The mooring system 102 physically restricts the platform 100 to motion within a designated area. In one non-limiting arrangement, the mooring system 102 may include multiple mooring lines 150 connected to the seabed 12 using suitable equipment/structures. The mooring lines 150 may be taut or catenary and anchored to seabed structures such as piles or drag anchors resting at the seabed 12. Each mooring line 150 attaches to the hull 110 via suitable mechanisms such as winches or stoppers. While four mooring lines 150 are shown, greater or fewer mooring lines 150 may be used.

[0018]The platform 100 may be configured to maintain stability irrespective of a direction from which a destabilization force, such as a wave or wind, acts on the hull 110. In embodiments, the planar walls 122, 124 of the hull 110 may be arranged to form a rectilinear shape when viewed along the vertical axis 160. The rectilinear shape lies along a plane orthogonal to the vertical axis 160. As used herein, a rectilinear shape is a shape defined by two sets of parallel sides, the two sets sides being at right angles relative to one another. The rectilinear shape may be partial or complete. As illustrated, the walls 122, 124 may be symmetrically distributed about a vertical axis 160. The vertical axis 160 is aligned with gravity, i.e., orthogonal to the horizon.

[0019]Referring to FIG. 2, the walls may include inclined walls 122a-d that define a perimeter of the flared section 114 and vertical walls 124a-d that define a perimeter of the lower deck section 116 below the flared section 114. The term “perimeter” refers to the boundary between the interior and the exterior of the platform 100. It should be noted that every side of the hull 110 may have about the same surface area against which a force such as wave motion can act. This may be obtained, in part, by configuring each set of walls, here inclined walls 122a-d and 124a-d, to have substantially the same width dimension. Exemplary width dimensions are labeled with numeral W. The width dimension W is the dimension of the side of the wall that defines a perimeter that lies along a plane orthogonal to the vertical axis 160. By “substantially,” it is meant the widths do not have an aspect ratio of greater than 2:1. In some embodiments, the widths W do not vary more than twenty percent relative to one another. Thus, the response of the hull 110 is generally the same irrespective of which side of the hull 110 encounters that force, such as wave motion. That is, the mobile platform 100 is not susceptible to greater instability because a vector of a destabilizing force acts on one side as opposed to another side of the hull 110. By way of contrast, the elongated shape of a vessel such as a barge (not shown) causes significantly different responses to a wave impinging the bow or stern as opposed to impinging the starboard or port sides.

[0020]In the illustrated embodiment, the hull 110 has chamfers 130, which are planar walls, formed at the corners of the flared section 114 and at the corners of the lower deck section 116. The chamfers 130 are also symmetrically distributed around the axis 160 and have substantially the same width dimension relative to one another. The chamfers 116 may be oriented to align with the adjacent walls. For example, the chamfers 130a-d may be inclined in the same manner as walls 122a-d and the chamfer 130e-h may be vertical to align with the vertical walls 124a-d.

[0021]It should be noted that, when viewed from the top or along the vertical axis 160, the perimeters of the platform 100 have a generally an octagonal shape. The octagonal shape lies along a plane transverse to the vertical axis 160. It should be also be noted that the octagonal shape is a composite of two partial rectilinear shapes. That is, the perimeter of the hull 110 may be formed by the walls 122a-d having a first rectilinear shape, e.g., a square, and the chamfers 130a-d having a second rectilinear shape, e.g. a square. In this embodiment, the first and the second rectilinear shape separately define only a portion of the perimeter because the walls 122a-d and the chamfers 122a-d are effectively segments and non-contiguous. Thus, the perimeter of the hull 110 is defined by a contiguous octagon, which is a composite of the first rectilinear shape and the second rectilinear shape. Likewise, the walls 124a-d and chamfers 130e-h, both of which define a segmented rectilinear shape, collectively define a continuous octagon. Accordingly, the perimeter of the hull 110 may be defined by one or more sets of symmetrically arranged planar walls that at least partially define a rectilinear shape. Further, the planar walls in each set have substantially the same width dimensions. In embodiments, the rectilinear shape may be a square or a rectangle.

[0022]Additionally, the mooring system 102 may be configured to further enhance stability. For example, the mooring lines 150, one set of which has been labeled, may be symmetrically distributed about the hull 110. The mooring lines 150 may be arrayed symmetrically about the vertical axis 160 and connected to suitable fixtures at the chamfers 130e-h. In some embodiments, the mooring lines 150 may be secured only at the chamfers 130e-h. In other embodiments, the mooring lines 150 may be secured at the chamfers 130e-h and also extend to one or more control assemblies attached to the flared section 114. For example, the chamfers 130e-h may have pulley wheels and the control assemblies (not shown) attached to the flared section 114 may include motorized drums. While four mooring lines 150 are shown, greater or fewer mooring lines 150 may be used. It should be noted that the symmetrical distribution of the mooring lines 150 further enhances the stability of the platform 100 when encountering destabilizing forces irrespective of the direction from which such forces impinge on the platform 100.

[0023]Referring to FIG. 3, there is schematically illustrated a sectional side view of the platform 100. In embodiments, the hull 110 is constructed to provide the necessary buoyancy to float the offshore platform 100 along a surface 14 of the water 10. That is, the offshore platform 100 does not use pontoons or other floatation devices for buoyancy.

[0024]In one arrangement, a ballast system 170 may be used to control and adjust the draft of the hull 110. The ballast system 170 may include one or more water-tight compartments 172 and one or more fluid movers 174. The compartments 172 are disposed within a perimeter 176 of the hull 110. The compartments 172 may be a collection of chambers, which may be hydraulically interconnected or hydraulically isolated. The fluid mover(s) 174 flows sea water into and out of the chambers 172. Illustrative fluid movers include active devices such as pumps and passive devices such as valves, spigots, ports, etc. The compartments 172 completely horizontally encircle at least some of the decks 120. That is, while FIG. 3 shows the compartments 172 on two sides of the platform, all sides of the platform 100 will have one or more compartments 172. The compartments 172 may be continuous or segmented, but still extends along all sides of the hull 110 as noted previously. While floatation devices may be used as ancillary or back-up floatation systems, at least a majority of the required floatation is provided by the ballast system 170 and the hull 110 itself under intended operations.

[0025]Referring to FIG. 3, the compartments 172 are positioned to separate at least some of the decks 120 from the perimeter 176 of the hull 110. By “separate,” is meant being physically interposed between at least a portion of the decks 120 and a portion of the hull 110, wherein the portions lie on the same plane orthogonal to the vertical axis 160 (FIG. 1). Thus, the compartments 172 can provide some measure of protection if an adjacent portion of the hull 110 is structurally compromised such as by impact. In some embodiments, the decks 120 adjacent to the compartments 172 are completely interior of the compartments 172. In other embodiments, the decks 120 adjacent to the compartments 172 are partially interior of the compartments 172.

[0026]Referring to FIG. 4A, there are shown various non-limiting modes of use for offshore platforms according to the present disclosure. In some modes of use, one or more platforms 100, 100a may be used in conjunction with offshore wind turbines 200. Suitable electrical cables and equipment at the offshore platforms 100, 100a may be used to receive electrical power from the wind turbines 200 and transmit the electrical power to another location. In other modes of use, the platforms 100, 100a may be used with one or more offshore platforms 202 that are used to drill and/or produce hydrocarbons from a subsea well. In still other embodiments, the platforms 100, 100a may be used to house data processing facilities and/or telecommunication facilities. Additionally, it should be noted that the platform 100a, while utilizing a generally box-like symmetrical shape, does not use flaring or include chamfers. Therefore, the vertical walls of the platform 100a define a rectilinear shape that is a contiguous square. Thus, offshore platforms according to the present disclosure are not limited to the particular configurations that have been illustrated.

[0027]Referring to FIG. 1, the platform 100 may be constructed at a shipyard or other similar facility and towed to a selected offshore location. In some embodiments, portions of the mooring system 102, such as the seabed structures and the lines 150, may be installed beforehand. When appropriately positioned, the platform 100 may be secured using the mooring system 102. Also, the ballast system 170 (FIG. 1) may be operated to obtain the desired draft for the hull 110. In some embodiments, the draft is adjusted periodically. In other arrangements, the draft is designed to fixed and changed only if needed.

[0028]FIG. 4B, illustrates another variant of an offshore platform according to the present disclosure. In this embodiment, a platform 100b is positioned on a body of water 10 that is shallow enough that the platform 100b rests on the seabed 12. This water depth may be less than 60 meters. Because of the gravity anchoring of the platform 100c, there is no need for a mooring system.

[0029]While the foregoing is directed to embodiments of the present disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.