KR20060039871A - Method for Producing Reduced-Rise Floating Structure - Google Patents

Abstract

The present invention provides a method for installing a heavy plate 100 on a floating structure 10. The method allows the manufacture of the floating structure 10 and the heavy plate 100 at shore while providing installation of the heavy plate on the floating structure at sea.

Description

METHOD FOR FABRICATING A REDUCED-HEAVE FLOATING STRUCTURE}

The present invention relates to a method for installing a rise plate on a floating structure, for example a spar, and to a floating structure produced by the method. The method includes providing a lift plate and a floating structure at a joining point in the water, and providing a method of connecting the lift plate to the floating structure.

As the petroleum industry explores deep-water offshore locations to find hydrocarbons resources, techniques for recovering these hydrocarbons must be developed. More floating structures, as opposed to bottom-founded structures, are used in these deep sea applications. Particular floating structures used in the petroleum industry in deep sea operations are spar or deep-draft caisson vessels (DDCVs), which are long vertically-placed when they are in floating operation positions. The upper part of the waterline with floating hulls or caissons, supporting drilling and / or production decks, and the lower part below the ocean waterline providing buoyancy for the hulls and decks. Equipped. The spar or DDCV can be anchored to the seabed using a mooring line. Vertical pipes, known as risers, serve as conduits for the production of hydrocarbons and / or provide wells and submerged wells in the sea to provide access for drilling or workover activities. It can be used to connect a spar or DDCV.

Typically, the spa hull is cylindrical and typically has a buoyancy section at its upper end, a skirt section at its middle, and a soft tank section at its lower end. Typically, buoyancy zones are hard tanks that provide the buoyancy required for a spa platform and can withstand hydrostatic pressure. The soft tank provides buoyancy for initial horizontal tow and subsequent upending. Once in place, both the skirt area and the soft tank can be filled with sea water. They are open to the sea from the bottom of the hull. In some cases, the soft tank may be ballasted with heavy materials such as ores or concrete for additional stability.

Typically, a deep sea hull of a spa, which can extend below the wave region of the body of water, provides a good overall travel response, such as the rise or vertical movement caused by wave forces in the water. This reduction in motion has several functional advantages, including the ability to use top-tensioned risers with well-control trees of surfaces for wells used to produce the field. Which gives the operator more options for efficiency and reduced cost.

Because of the severity of some offshore environments, further reductions in the rise, pitch and roll motion of the DDCV structure may be required. Many solutions have been proposed, including the attachment of lift plates arranged horizontally on the DDCV hull. See, for example, US Pat. No. 5,558,467 to "Deep Sea Instruments" and US Pat. No. 5,722,797 to "Floating Cayson for Offshore Production and Drilling." Climbing plates provide added mass and damping to floating structures by increasing the horizontal surface at a depth below the active wave action disposed near the surface of the ocean.

However, a logistical problem exists in implementing the rise plate concept. For convenience and cost effectiveness, offshore floating structures are always built on land and then transported to sea for installation. This is often cost-prohibitive and logistically difficult to manufacture offshore floating structures at sea. Regarding the rise plate structure, fabricating and combining spar hulls and rise plates on land can provide similar efficiency and cost savings. However, the reduced-elevating structure still has to be transported by sea for installation. Due to the significant draft demand generated by the rise plate structure, the transport of the spar from the sea's fabrication point to the offshore installation point is quite impractical.

Therefore, what is required is a method of providing a rising plate horizontally disposed on a floating structure, such as a DDCV or spar structure, which rises on land while providing attachment of the rising plate to the floating structure at or near an installation point in the water Allow the manufacture of plates and floating structures. The present invention satisfies this need.

For further information, see US Pat. No. 3,101,798, Offshore Drilling Apparatus; U.S. Patent No. 3,572,041, Spar Floating Production Facility; US Patent No. 3,921,557, floating storage unit; US Pat. No. 4,606,673, Spa buoy construction and method of operation having a production and oil storage facility; U.S. Patent No. 4,702,321, drilling, production, and deep sea oil storage caissons; Lowd, Judson D. and Hill, E. C., The Use of Spa Buoys Designed for Temporary Production Processes, Offshore Technology Conference, OTC 1333, May 1971; US Patent No. 5,558,467, Offshore Organization of the Deep Sea; US Pat. No. 5,722,797, floating caisson for offshore production and drilling; US Patent No. 6,206,614, floating offshore drilling / production structure; Tanaka, K. et al., Studies on the installation of caisson submerged in deep waters, Offshore Technology Conference, OTC 5606, May 1987; Walker, S., et al., STAPLA-Design of floating production vessels of various draft semi-submersible, proceedings of the first European offshore mechanical symposium, 8 1990 month; US Patent No. 5,609,442, Offshore Apparatus and Methods for Oil Operations; See US Pat. No. 5,924,822, a method for installing decks on offshore substructures.

The present invention includes a method for installing a lift plate on an offshore floating structure. The method includes providing a lift plate and a floating structure at the point of attachment of the water. The lift plate includes a template capable of receiving a horizontal cross section of the floating structure. The method includes vertically placing the lift plate and the floating structure along a common vertical axis. The method includes connecting the floating structure to the template of the lift plate and connecting the lift plate to the float structure.

1A is a side view of a typical DDCV or spar structure.

FIG. 1B is a top view of the hull of the DDCV or spar structure of FIG. 1A. FIG.

2A is a plan view of one embodiment of a heavy plate that may be used in accordance with the present invention.

2B is a schematic diagram of FIG. 2A;

3A is a side view of the floating structure and the rise plate provided at the joining point of the water.

3B is a schematic diagram showing the vertical arrangement of the floating structure and the lift plate according to one embodiment of the present invention.

3C is a schematic diagram of one embodiment in which the guideline is used to control the movement of the rising plate submerged.

4 is a schematic view of one embodiment of the present invention with a lift plate disposed below the lower end of the floating structure.

5 is a schematic illustration of one embodiment of the present invention in which the connection of the lift plate to the floating structure is made by grouting an annulus therebetween.

6A is a schematic representation of one embodiment of a lift plate that may be used in accordance with the present invention.

6B is a side cross-sectional view of the lift plate of FIG. 6A.

FIG. 7A is a side view illustrating one embodiment of a lift plate provided at a joining point of the water; FIG.

FIG. 7B is a side view showing another embodiment of a lift plate provided at the joining point of the water. FIG.

FIG. 8 is a side view illustrating one embodiment of a lift plate provided at the joining point of the water where the lift plate serves as a vessel for transporting a deck; FIG.

9 is a side view showing the vertical arrangement of the lift plate and the hull according to the invention.

10 is a side view showing one embodiment of the present invention with a lift plate disposed over the upper end of the hull.

11A-11C are side views of one embodiment of the present invention showing the placement of a lift plate from the upper end to the lower end of the hull.

12A is a plan view illustrating a lift plate that may be used in accordance with one embodiment of the present invention.

12B is a schematic representation of the lift plate of FIG. 12A.

13A-13B are side views of lift plates in the form of split vessels that may be used in accordance with one embodiment of the present invention.

The invention will be described in connection with the preferred embodiments. However, with respect to the extent to which the following description describes specific embodiments or specific uses of the invention, it is intended to be illustrative only and is not to be construed as limiting the scope of the invention. On the contrary, as defined by the appended claims, it is intended to cover all alternatives, modifications, and equivalents falling within the spirit and scope of the present invention.

As used herein and in the claims, the term "floating structure" refers to any structure that can float in a body of water. Floating structures refer to structures that float when they are in their final installation location, but such structures may also sink into the water body, for example, by ballasting. Examples of but not limited to floating structures include offshore floating structures, spars, classic spas, caisson vessels for deep seas, truss spas, cell spas, pipe spas and the offshore oil industry. It includes other structures used for.

As used herein and in the claims, the term “spa” refers to any sparse floating structure including, but not limited to, existing spas, deep sea caisson vessels, truss spas, cell spas, and pipe spas. do.

As used herein and in the claims, the term "heave plate" refers to any device suitable for attachment to a floating structure, providing additional mass and depth below the active wave area of the water body. It is useful for damping floating structures by increasing the horizontal surface area at. The lift plate may be of any shape, for example, a relatively planar member of rectangular, circular, polygonal, oval, or other regular or irregular shape. The lift plate may include a void area that may be used as a template and may facilitate attachment to the floating structure.

As used herein and in the claims, the term "template" is meant to refer to the cut portion of the lift plate. The template may penetrate partially or completely through the lift plate. In an alternative case in which the template has passed completely through the lift plate, holes or outlets are formed in the lift plate. In an alternative case where the template only partially penetrates through the lift plate, wells or depressions are created in the lift plate. Further, the template may be designed to partially penetrate some portions of the lift plate and to completely penetrate a portion of the lift plate, for example to allow moonpool opening in the lift plate to be attached to the bottom of the spar. . The template can be designed in any shape and size such that the lift plate is fixed around the floating structure.

As used herein and in the claims, the terms "hull" and "caisson" are used interchangeably to describe the underwater portion of a spar that provides buoyancy and stability.

In an alternative embodiment, the floating structure applicable to the present invention is a DDCV or spar structure as shown, for example, in FIG. 1A. By "floating" structure it is meant that the structure floats when present in its final installation position. As described herein, the method of attaching a lift plate may be used on any float structure to eliminate or dampen vertical or heavy motions acting on the float structure. In an alternative embodiment, the lift plate is mounted on a DDCV or spar structure, which is typically an upper portion 20 on the surface of the ocean 30 supporting the deck 40 and an ocean 30 Has a substantially rigid body 10 that is not necessarily cylindrical with a lower portion 50 below the surface of the < RTI ID = 0.0 > The spar structure can be of different geometric designs, for example cylindrical, multi-cylindrical, polygonal, multi-polygonal, oval, octagonal or pentagonal. An anchor line 25 is used to anchor or moor the floating structure to a seafloor. FIG. 1B is a top view of the spa shown in FIG. 1A. This figure shows a sectional view 70 of a spar hull and the door pool 71 extending through the spar. The door pool can be sized to accommodate drilling equipment and a production riser.

Referring now to FIGS. 2A and 2B, the lift plate 100 has a large horizontal plane zone that is significantly larger than the horizontal section 70 (as shown in FIG. 1B) of the floating structure 10. The specific size of the lift plate 100 may be determined by one of the prior art in the art based on the size of the floating structure and the environmental effects described. The lift plate 100 is not limited to any particular shape, which may be round, square, rectangular, or any other shape. The lifting plate 100 may include a template 110 in the form of an opening having a cross section capable of receiving a horizontal cross section 70 of the floating structure 10, as described below. The term "horizontal" is used in relation to the floating structure in its final installation position, ie the horizontal cross section 70 is perpendicular to the longitudinal axis of the DDCV or spar floating structure formed in a cylindrical shape as shown in FIG. Do. Lift plate 100 may be attached to the bottom and / or intermediate levels of the spar hull.

3A and 3B illustrate alternative embodiments of the present invention. The floating structure 10 and the lift plate 100 are provided at the offshore coupling point 5. The offshore joining point is preferably, but not necessarily, near the final installation location of the floating structure, ie near the field or production location to minimize the towing distance after the joining operation.

Referring to FIG. 3B, the lift plate 100 has sufficient vertical clearance 130 between the lift plate 100 and the bottom of the floating structure if the lift plate 100 and the floating structure are vertically aligned. Descend below the surface of the ocean to a depth capable of providing Guide lines 160 (shown in FIG. 3C) attached from the vessel vessel 150 to the lift plate 100 are used to control the alignment and depth of the lift plate 100 in this lowering process. Can be used. Next, as shown in FIG. 4, the floating structure 10 may be disposed vertically (if not already in a vertical position), and may be aligned along a common vertical axis with the lift plate 100. 110 is present below the hull of the floating structure 10. Subsequently, the floating structure 10 may be ballasted and lowered into the template 110 of the rising plate. In addition, the guide line 160 may be used to raise the lifting plate template 110 to connect the floating structure 10. Latching devices 170 may be present on the floating structure 10 and / or the lift plate 100, which may be operated in a combination of the two structures. Referring now to FIG. 5, once the lift plate 100 is disposed at the lower end of the floating structure 10, the final connection is an annulus between the template 110 and the floating structure 10. Can be achieved by grouting 180. In addition, mechanical means can be used to make the final connection between the lower end of the floating structure and the lift plate.

After the rise plate 100 is structurally connected to the floating structure 10, the combined structure, i.e., the reduced-heave caisson vessel, may be towed to a field position if necessary. . The provision of the deck and the installation of facilities in the field position can be accomplished using conventional techniques.

Referring now to FIGS. 6A and 6B, one alternative template 110A for an embodiment forms an opening in a lift plate 100A that can receive a horizontal cross section 70 of the floating structure 10. do. Alternatively, the opening forming the template 110A may only extend through a portion of the lift plate 100A. In other embodiments, the template may alternatively include an opening in the lift plate that may receive a horizontal cross section 70 of the floating structure 10 through the entire rise plate 100A thickness. In an alternative embodiment in which the template opening 110A extends only through a portion of the path through the lifting plate 100A, a portion of the surface area of the template opening 100A may alternatively extend through the entire lifting plate. It may be sized to include a door-size opening 111A for the passage of the drilling rig and riser pipe. For example, the opening of the door pool size shown in FIGS. 6A and 6B may be sized to match the door pool 71 shown in FIG. 1B.

Referring now to FIG. 7A, the lift plate 100 useful in embodiments of the present invention may be configured such that buoyancy and seaworthy may be present, alternatively a vessel 100B that may be transported on the surface of the water. Can be used as The lift plate / vessel 100B may incorporate an independent power and navigation system to lift to the offshore coupling point 5, but the lift plate / vessel 100B may also incorporate the lift plate 100. Since the vessel 100B may be installed on the floating structure 10, it is preferable that the vessel 100B is a simplified barge and is transported to the coupling point 5 using a second vessel. The vessel 100B may be configured to have a capacity for various buoyancy, for example, the vessel 100B may be a floating chamber (not shown) or the vessel 100B below the surface of the ocean. Other means for adding the ballast to submerge. In addition, the lift plate 100 may be configured without buoyancy, such as a truss or girder stiffened plate 100C, as shown in FIG. 7B. This buoyant lift plate 100A may be transported to the installation point, for example, on transport barge 190C, or by other means.

Referring now to FIG. 8, another embodiment of the present invention is shown in which the lifting plate 100D is first used as a vessel for transporting the deck 40 to the joining point 5. After the weight of the deck 40 is transferred from the lift plate / vessel 100D to the float structure 10, the lift plate / vessel 100D is used for the float structure 10 as a lift plate. It is placed and attached at a predetermined point along the depth of the hull.

In order to practice this embodiment of the invention, both the lifting plate 100 and the floating structure 10 are provided at the joining point 5. As shown in FIG. 8, the lift plate 100 is first used as a vessel 100D for transporting the drilling and production deck 40, or the upper side, to the coupling point 5. The deck 40 and the vessel 100D can be manufactured and operated onshore using standard techniques, which can provide cost savings as opposed to operating the deck offshore.

Referring now to FIG. 9, the floating structure 10 can be provided at the joining point 5 and is disposed vertically if it is not already in a vertical position and is locked below the surface of the ocean 30. Positioning and locking the floating structure 10 vertically can be accomplished using various known techniques. The depth through which the floating structure can be submerged is selected to provide sufficient vertical clearance 130D between the submerged floating structure 10 and the lift plate / vessel 100D. The locked structure 10 may remain on a sea floor as shown in FIG. 9 or may float in a selected path. Thus, in this alternative embodiment, a sufficient vertical gap 130D between the floating structure 10 and the vessel 100D may be provided. Referring to FIG. 10, since the lifting plate / vessel 100D may be disposed vertically above the locked floating structure 10, the template 110D is substantially aligned through the locked structure 10. The coupling line 250 may be used to connect the floating structure 10 and the template 110D. After the floating structure 10 and the deck 40 are connected, the floating structure 10 may be deballasted, and the weight of the deck 40 is the lifting plate / vessel 100D. Is delivered to the floating structure (10). After this weight transfer, the buoyancy of the lifting plate / vessel 100D is reduced, for example the vessel 100D is ballasted by flooding, as shown in FIGS. 11A-11C, It is lowered to the lower end of the floating structure 10 along the length of the hull. Thereafter, the vessel 100D is structurally connected to the bottom of the floating structure 10, or to any other predetermined depth, and is used as the lift plate 100. For example, the lift plate 100D may be finally connected after reaching the position shown in FIG. 11B.

After the lift plate 100D is structurally connected to the floating structure 10, the reduced-lift caisson vessel and deck can be lifted to the field position and, if necessary, installed using conventional techniques. .

Referring now to FIG. 12A, the lift plate / vessel 100D forms a template that forms an opening in the lift plate / vessel 100D that can accommodate a horizontal cross-section 70 of the floating structure 10. 110D). As is apparent, the opening forming the template 110B for this embodiment extends through the height of the lift plate / vessel 100D, as shown in FIG. 12B.

If the floating structure 10 includes equipment or obstructions on the outside of the hull that may interfere with the transfer of the lift plate / vessel 100D from the top to the lower end of the floating structure 10, for example Fairleads or steel catenary riser porches in the template 110D allow unobstructed delivery of the lift plate 100D, as shown in FIGS. 12A and 12B. Can be provided for this purpose.

Referring now to FIGS. 13A and 13B, the lift plate / vessel useful for this embodiment may include a split vessel 100E that includes an upper portion 200 and a lower portion 210. . The split vessel 100E can be used as an introverting vessel for transporting the drilling and production deck 40 to the connection point 5. The upper portion 200 of the split vessel 100E may remain at the upper end of the floating structure 10 as a deck structure, but the lower portion 210 of the split vessel 100E may be used as a plate. It can be lowered or raised along the length of (10).

Another potential advantage of providing a lift plate on a DDCV or spar structure is that the vessel's hull can be designed smaller in size and ultimately smaller, thus providing cost savings in manufacturing. In general, the hull of the vessel should be of sufficient size to provide sufficient buoyancy to the weight of the deck and the hull, and of sufficient length to minimize the upward movement. A limiting factor for reducing the length of the hull may be upward movement. In other words, reducing the hull length can result in a lift that is too large to tolerate before the lift creates a buoyancy problem. By adding horizontally placed lift plates to reduce this movement, shorter DDCVs or spar structures in length can be fabricated, while at the same time achieving corresponding cost savings while maintaining sufficient buoyancy.

The methods described herein can be used to fabricate offshore floating structures for use in exploration and production of hydrocarbon resources in offshore. The offshore floating structure can be, for example, a conventional spar (eg deep sea caisson vessel (“DDCV”) or truss spar) with a deck or a production riser. In the case of the spa, the deck may support offshore hydrocarbon resource (ie oil and gas) exploration, drilling and production operations. The deck can be used to perform seismic data collection offshore. Alternatively, the deck may support offshore drilling equipment for oil and / or gas drilling operations. The deck may also support oil and / or gas production equipment for the production of oil and gas natural resources. The oil and / or gas produced can then be offloaded from the deck, for example by a pipeline to the shore or by a transport or barge, which can then be moved offshore. The oil and gas may then be refined into usable petroleum products such as, for example, natural gas, liquefied petroleum gas, gasoline, jet fuel, diesel fuel, heated oil or other petroleum products.

The present invention has been described in connection with preferred embodiments. However, to the extent that the following description is set forth with respect to particular embodiments of the invention or to particular uses, it is intended to be illustrative only and is not intended to limit the scope of the invention. On the contrary, it is intended to cover all alternatives, modifications and equivalents falling within the spirit and scope of the invention as defined by the appended claims.

All documents described herein are fully incorporated by reference for all jurisdictions, and such integration is allowed within that authority and is not inconsistent with this description in its scope. Although some dependent claims have a single dependent claim in accordance with US practice, each feature in any dependent claim may be combined with each feature of one or more other dependent claims according to the same independent claim or independent claims. have. Certain features of the present invention are described by a set of numerical upper limits and a set of numerical lower limits. It should be appreciated that the ranges formed by any combination of these limitations are within the scope of the present invention unless otherwise indicated.

Claims (23)

A method for installing a heavy plate on an offshore floating structure, (a) providing said riser plate and said floating structure comprising a template capable of receiving at least a portion of a horizontal cross section of said floating structure at an offshore joining site; (b) vertically placing the lift plate and the floating structure along a common vertical axis; (c) connecting the template of the lift plate and the floating structure; (d) connecting the lift plate to the float structure. The method of claim 1, wherein the floating structure is a spar. The method of claim 2, wherein the rise plate is connected to the floating structure, so that the rise plate is horizontally disposed. 4. The method of claim 3 wherein the lift plate is a vessel capable of receiving a variety of buoyancy. The offshore floating structure further comprises a deck. And said vessel with various buoyancy forces to mount a lift plate on an offshore floating structure that transports said deck to a point of engagement of said water. 4. The method of claim 3, wherein the rise plate is buoyant and free of offshore floating structures. 7. The method of claim 6, wherein the buoyant lift plate is transported on a vessel to a point of engagement of the water. 4. The method of claim 3, wherein the vertical placing step comprises locking the lift plate and placing the lift plate below the float structure. 10. The method of claim 8, wherein the template in the lift plate includes an opening extending through a portion of the height of the lift plate. 10. The method of claim 8, wherein the step of connecting comprises connecting an upper end of the template and a lower end of the floating structure. The method of claim 8, wherein said connecting step further comprises the use of guide lines. 4. The method of claim 3, wherein the vertical placing step comprises locking the floating structure and placing the floating structure below the rising plate. The method of claim 12, wherein the template in the lift plate includes an opening extending through the height of the lift plate. 13. The method of claim 12 wherein the step of connecting further comprises the use of a joining line. 13. The method of claim 12 wherein the step of connecting comprises connecting the bottom of the template and the top end of the floating structure. The method of claim 15 further comprising re-positioning the lift plate from an upper end of the float structure to a lower end of the float structure prior to the step of connecting the lift plate to the float structure. A method for installing a lift plate on a floating structure for offshore. 4. The method of claim 3 wherein the step of connecting comprises latching the lift plate to the float structure. 4. The method of claim 3 wherein the step of connecting comprises grouting an annulus between the lift plate and the float structure. 4. The lift plate of claim 3 further comprising the step of towing the joined floating structure and the lift plate to an offshore production position at the joining point of the water. How to install. 6. The method of claim 5, wherein the vertical placing step includes locking the floating structure and placing the floating structure below the rising plate. The method of claim 3, wherein (e) using the floating structure to produce a hydrocarbon resource of the offshore, the method for installing a lift plate on the offshore floating structure. The method of claim 21, and (f) transporting said hydrocarbon resource to the shore. 21. A floating structure made according to any of the preceding claims.

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