MXPA00008122A - Mudmats for offshore platform support - Google Patents

Abstract

A mudmat in which the bearing plates of the mudmat are fabricated of a non-corrosive, man-made structural material such as plastic. The plates, formed of such a material, are lightweight, easily fabricated and generally less expensive than the prior art plates and their associated support structure. In one preferred embodiment, the plates are formed of extruded polyvinyl chloride (PVC) or a fiber reinforced composite such as thermoset resin reinforced with glass fibers (GRP). The individual plates are supported by standard frame members. The PVC or GRP plates are of such a size, shape and weight that they can easily be transported to, assembled and attached to the offshore jacket at the jacket fabrication site. Being formed of such materials, the plates are corrosion-resistant, eliminating the need for cathodic protection. In addition, the PVC or GRP plates are much lighter in weight than the wood or metal plates of the prior art, such that they have much less impact on the buoyancy and weight of the jackets to which they are attached. In one preferred embodiment, the plates may be corrugated to enhance resistance to horizontal and vertical displacement forces placed on the offshore jacket.

Description

GRID FOR MUD OF PERFORATION OF THE SUPPORT OF MARITIME PLATFORM BACKGROUND OF THE INVENTION FIELD OF THE INVENTION The invention relates to an apparatus for temporarily supporting a maritime platform substructure or rigid maritime floating device on soft unconsolidated sea beds, and more particularly to a drilling mud grid that is light and resistant. to corrosion.

DESCRIPTION OF THE PREVIOUS TECHNIQUE Currently, many of the hydrocarbons produced from the earth are extracted from below the seabed. Several types of substructures have been used in these maritime extraction operations. Typically, the structures consist of a horizontal working platform or equipment platform that is supported on the surface of the water by a substructure, commonly referred to as a rigid maritime floating device. Rigid maritime floating devices are those most commonly manufactured on land, towed or transported by barge to the drilling site, and are descended to the proper position in the seabed. Generally a maritime rigid floating device is comprised of at least three substantially vertical legs that are interconnected by frame members or transverse braces to form a triangular or rectangular base, wherein one leg is placed at each corner of the base. In its vertical position, the rigid maritime floating device rests on the seabed with the lower part of the legs resting on the seabed or penetrating slightly into the ground. The floating rigid maritime artifact is secured to the seabed with piles that are driven through the legs or driven through sleeves attached to the legs. In many parts of the world, the seabed terrain is not consolidated and the excess of softness results in permissible support pressures that are too low. These soft marine beds commonly occur near the mouths of large rivers that discharge into the oceans. The sea beds in the world that exhibit high hydrocarbon content although they are characterized by soft soils from the river deltas include areas in the Gulf of Mexico, western Africa and Southeast Asia. The low support pressures of these unconsolidated sea beds create support problems for the rigid maritime floating device during the installation of the offshore platforms. Specifically, without proper support, the legs of a rigid maritime floating device will sink into the seabed, causing the rigid maritime floating device to fall to the side or be set lower than the design specifications. In any case, the fixation of the rigid maritime artifact due to a soft seabed can negatively affect the alignment of the rigid maritime floating device as it is placed in the drilling site. Speaking of the same subject, the difficulties arise frequently due to pile driving operations, which are contemplated within one or two weeks after the placement of a rigid maritime floating device in position on the seabed. As a pile is driven into the seabed through a sleeve, the leg or portion of the rigid maritime floating device to which the sleeve is attached tends to sink into the soft side under forces applied during the pile driving operation, affecting this way the general alignment of the rigid maritime floating device. One solution to the difficulties associated with unconsolidated seabeds is to provide a structure that distributes the downward forces applied to the rigid maritime artifact over a larger area of the seabed. The most common structure for performing this task is called a drilling mud grid. A drilling mud grid has a larger surface area that rests against the seabed (as opposed to the comparatively small surface area of a rigid marine floating craft leg), distributing the load of the rigid maritime floating device over a larger area of the seabed, thus allowing the maritime rigid floating device to be properly fixed on the soft seabed and provide stability during pile driving operations. The drilling mud grids are typically comprised of frame members that are attached to and provide support to a seating plate. The seat plate rests against the seabed and provides the largest surface area for force distribution. The drilling mud grids are attached by themselves to the bottom of a rigid maritime floating device, most frequently adjacent to the legs of the rigid maritime floating device. Originally, the seat plates were manufactured from wooden beams with large amounts of steel support structure to reinforce the seat plates. These wood drilling mud grids, however, are characterized by a number of disadvantages. The most suitable large beams in the manufacture of such drilling mud grids are difficult to obtain and comparatively expensive. .The drilling mud grids also require quantities of man-hours to assemble and require large amounts of steel to provide the necessary back-up support structure. Finally, although wood drilling mud grids provide some flotation in water, approximately 2107-4 4214 kilograms per square meter, such drilling mud grids are comparatively heavy in the air, weighing approximately 12642 to 16856.04 kilograms per square meter . The voluminous nature of those prior art drilling mud grids, ie large surface area combined with comparatively large weights, made such drilling mud grilles difficult to handle and install. One solution to the disadvantages associated with wood drilling mud grids has been to manufacture the grid seat plates for drilling mud outside stiffened steel plates, corrugated steel plates or steel sheet piles. These "steel drilling mud grills" offer a number of improvements over the wood drilling mud grids. Steel drilling mud grids require less back support structure than wood drilling mud grids. In addition, steel drilling mud grids typically weigh less than grids for wood drilling mud. Specifically, steel drilling mud grills typically range from approximately 9270.82 to 12642 kilograms per square meter. However, steel drilling mud grids have their own disadvantages. The steel drilling mud grids are comparatively heavier and are characterized by high manufacturing costs. More importantly, steel drilling mud grids are subject to high corrosion regimes unless they are protected in some way. The functional life of the drilling mud grids is approximately one or two weeks required for the pile driving operations to be completed. After the installation of the piles, the drilling mud grids become functionally useless for the rest of the life of the offshore platform. However, maritime platforms are designed for a typical life of 10, 20 or 30 years, depending on the development of the oil field and gas. Although the drilling mud grids are functionally useless, the steel drilling mud grids are by nature parasitic and since they contribute to the loss of the cathodic protection that is provided for the maritime platforms. The cathodic protection is necessary to avoid the oxidation and corrosion of the maritime platform and to avoid the subsequent reduction in its structural integrity. Aluminum alloy ingots typically serve as protection anodes to protect the shipping platform. Since the steel drilling mud grids are generally attached to a rigid seaborne floating device by welding to become part of the structure of the rigid marine floating craft. The drilling mud grids are electrically connected to the marine platform and contribute to the loss of protection anodes. One solution to the problem of cathodic loss by drilling mud grids is to remove the drilling mud grids from the structure of the rigid marine floating device after the pile drive is complete. Typically, the removal of the drilling mud grid includes the use of divers that must be fixed to the seabed to cut the drilling mud grids from the rigid maritime floating device. In addition, since the drilling mud grids are generally joined by permanent frame structures, the drilling mud grids are extremely difficult to remove in one piece, and they must be cut into smaller pieces that can be maneuvered around the structure. permanent frame and elevated towards the surface. This process is repeated again and again for each piece of the drilling mud grid until all the parts have been removed. Although effective, the removal of the grid for drilling mud is undesirable because the process is costly and time-consuming. Therefore, the need remains for drilling mud grids that do not represent a loss of the cathodic protection provided for the maritime platform itself, nor do they require the removal that follows its useful life. Returning to the weights of the wood and steel drilling mud grids, rigid maritime floating devices are typically designed to have small amounts of reserve float, approximately 7-12% by weight of the rigid maritime floating device, to allow the ease in lifting, handling and positioning. The addition of heavy wood or steel drilling mud grids at the base of a rigid maritime floating device can prevent this flotation and the beneficial effects achieved by flotation. To counteract the weight of the drilling mud grids, therefore, additional flotation must be added to the upper portions of the rigid maritime floating device. This is generally achieved by providing larger diameter members for the legs and frame members. However, by doing so, not only is the general preserve of the rigid maritime floating device increased, but also the susceptibility of the artifact to the external sling forces that also increase. In other words, due to the small amounts of reserve flotation, rigid maritime floating devices are generally very sensitive to weight and flotation forces. As larger diameter members are incorporated into the structure, this sensitive balance is altered. Specifically, the larger diameter members provide a greater surface area against which ocean currents and slings can act. Not only may this additional bridging be required to withstand those lateral forces, it may result in the need for improved pile support through the addition of more piles or an increase in the depth at which the piles are driven into the seabed. For the foregoing reasons, the need remains for drilling mud grids that do not adversely affect the weight and floatation of a rigid maritime floating device to the extent of prior art drilling mud grids. Drilling mud grids should avoid the need for cathodic protection or removal. In addition, the drilling mud grids must exhibit lower manufacturing costs than prior art drilling mud grids. Finally, it would be desirable to provide drilling mud grids that can be manufactured and installed more easily than prior art drilling mud grids.

BRIEF DESCRIPTION OF THE INVENTION These and other objectives are achieved through a drilling mud grid in which the seat plates for the drilling mud grid are made of a non-corrosive, hand-made structural material such as plastic. The plates formed of such material are light, easy to manufacture and generally less expensive than prior art plates and their associated support structure. In a preferred embodiment, the plates are formed of extruded polyvinyl chloride (PVC) or a fiber reinforced composite such as a glass fiber reinforced thermosetting resin (GRP). The individual plates are supported by standard structure members. The PVC or GRP plates are of such a size and weight that they can be easily assembled and attached to the rigid marine floating craft at the artifact manufacturing site. When forming such materials, the plates are resistant to corrosion, eliminating the need for cathodic protection. In addition, the PVC or GRP plates are much lighter in weight than the wooden or metal plates of the prior art, so that they have much less impact on the flotation and the weight of the rigid marine floating devices to which they are attached. . In a preferred embodiment, the plates are corrugated to increase their moment transport capacity and for a better resistance of the horizontal and vertical displacement forces imposed on the rigid maritime floating device during their installation phase.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 * is a perspective view of a vertically oriented rigid seaborne floating device equipped with drilling mud grids adjacent to each leg. Figure 2 is a plan view of the lowermost level of the rigid maritime floating device of Figure 1, showing the position of the drilling mud grids in relation to the legs and the frame of the rigid maritime floating device. Figure 3 is a side view of the perforation slurry grid plates showing interconnected and to the grid support structure for drilling mud. Figure 4 is a partial cross-sectional view of a plate of figure * 3, illustrating a possible means of attaching a plate to the drilling mud grid support structure. Figure 5 is a side view of one embodiment of a grid plate section for individual drilling mud.

DETAILED DESCRIPTION OF THE PREFERRED MODALITIES. In the detailed description of the invention, similar numbers are used to designate similar parts. Different items of equipment such as fasteners, accessories, etc., can be omitted to simplify the description. However, those skilled in the art will realize that such conventional equipment can be used as desired. With reference to Figure 1, there is shown a perspective view of a marine platform 8 having a maritime rigid floating device 10. The rigid marine floating device 10 includes corner legs 12 and rigid marine floating craft frame. The maritime rigid floating artifact shell 14 generally consists of generally horizontal members 16, diagonal members 18 and substantially vertical members 20, which provide lateral support for the legs 12 and horizontal support for a platform 13. Attached to each leg 12 are one or more pile sleeves (not shown) for the reception of the piles 23 that are driven deep into the seabed to secure the rigid maritime floating device on them. After the pile driving operations have been completed, the piles are permanently fixed to the inside of the legs 12 or pile sleeves using any standard method, such as cementation or welding. Located near the bottom of each leg of rigid floating marine device 12 are the grids for drilling mud With reference to Figures 2 and 3. each drilling mud grid 24 generally comprises a support structure 26 to which a plurality of plates or seating plates 28 are attached. In one embodiment, the supporting structure 26 which is best shown in Figure 4, it is comprised of a filled core beam 30 to which the square iron 32 is attached at each end of the filled core beam. The plate 28 is shown attached to a square iron 32 using any standard fastener 34, as in the Example only a self-tapping screw. In this particular embodiment, the filled web beam 30 provides the backup support for the plate 28. However, due to the substantial transverse thickness of the filled web beam 30, the filled web beam 30 is not easily placed to receive the fastener 34. Therefore, to improve the ease of manufacture, the square iron 32, which has a transverse thickness less than that of the filled core beam 30, is used as the point at which the plate 28 is attached to the support structure 26. Turning to Figure 2, the support structure 26 is attached to the rigid marine floating craft by means of the frame of the artifact 14. Specifically in Figures 1 and 2, a plurality of full-soul beams are shown. 30 attached to and extending between the horizontal members 16. Although the plates 28 may have any shape without departing from the spirit of the invention, in one embodiment shown in Figures 3 and 5, each individual plate 28 is in the form of z (Figure 5) so that when they are joined together, the plates 28 form a grid surface for general corrugated drilling mud (Figure 3). In this embodiment, each plate is formed of first and second horizontal portions 36a, 36b and has a substantially vertical portion 38 positioned therebetween. Each horizontal portion is provided with a connecting structure consisting of a ball structure 40 or a receptacle structure 42 for attaching a first horizontal portion 36a of a plate to a second horizontal portion 36b of an adjacent plate. Again, the plates can be joined using a standard form, although it has been found that the "press-fit" design of the ball and receptacle configuration further increases the ease of manufacture. In any case, when joined in adjacent plates in this manner to form a grid surface for corrugated drilling mud, the drilling mud grid 24 provides lateral and vertical support to the rigid maritime floating device 1. Specifically, when placed on an unconsolidated or soft seabed, the drilling mud grid 24"is fixed" within the seabed so that the vertical portions 38 extend down into the seabed, forming a hollow foundation for the rigid seaborne floating device 10. Of course, plates 28 need not be in the form of z but can be of any design, such as, for example, flat or sculpted, to have any particular shape that may be desirable for a specific seabed. In addition, such plates may be placed for attachment anywhere on the maritime rigid floating device 10 or its related structure and may be of any configuration necessary for a particular function, such as for example rectangular or triangular. The novelty of the present invention lies in the construction materials. Therefore, the prior art drilling mud grills, and specifically their horizontal seat plates, have been made of wood or metal, exhibiting the numerous disadvantages referred to above. The plates 28 of the present invention are made of a non-corrosive handmade structural material such as plastic. The plates 28, formed of such material are lightweight, easy to manufacture and generally less expensive than prior art plates. further, being lighter than the plates of the prior art, the plates 28 require less support structure, which therefore decreases the overall weight of the drilling mud grid 26 when compared to the prior art. In a preferred embodiment, the plates 28 are formed of extruded polyvinyl chloride (PVC) or a fiber reinforced composite such as a glass fiber reinforced thermosetting resin (GRP). Such plates weigh approximately 1474.90 to 2528.40 kilograms per square meter in the air and approximately 632.10 to 1264.20 kilograms per square meter in the water, so that both as in and out of the water, the plates 28 weigh less than the plates of the prior art. . Those skilled in the art will understand that plates 28 can be formed from any type of hand-made plastic material without departing from the invention. In any case, such plastic materials are much easier and less expensive, in their formation in the desired contours for a particular purpose than the prior art plates made of wood or steel. Therefore, the plates of the invention also provide a selection capacity in the design that the prior art plates do not have. A plastic material that has been found to be particularly suitable for the invention is grade 1 PVC. The drilling mud grille of the invention provides a support system for light maritime rigid floating craft which is manufactured transports easily installed and maintained. The grille plate-s for drilling mud are resistant to corrosion, eliminating the need for cathodic protection so common in the industry today. In addition, the plates provide design flexibility over the prior art plates so that the plates of the invention can be more easily sculpted to meet specific use criteria. While certain features and embodiments of the invention have been described herein in detail, it will be readily understood that the invention encompasses all modifications and improvements within the scope and spirit of the following claims.

Claims (12)

1. CLAIMS 1. A drilling mud grid for supporting a rigid floating platform device, the drilling mud grid comprising: at least one ground support plate; and frame members that are attached to and provide support to at least one seat plate, wherein the seat plate is formed of plastic.
2. 2. The drilling mud grid according to claim 1, characterized in that the base plate is formed of polyvinyl chloride.
3. 3. The drilling mud grid according to claim 1, characterized in that the base plate is formed of a resin reinforced with particles.
4. 4. The drilling mud grid according to claim 3, characterized in that the resin reinforced with particles is thermosetting resin reinforced with glass fiber.
5. 5. The drilling mud grid according to claim 1, characterized in that the seat plate is substantially flat.
6. 6. The drilling mud grid according to claim 1, characterized in that the seat plate is corrugated.
7. 7. The drilling mud grid according to claim 1, characterized in that the seat plate comprises an upper gripping plate; and a lower seat plate.
8. 8. The drilling mud grid according to claim 7, characterized in that the upper and lower seat plates are joined together with a frame.
9. 9. The drilling mud grid according to claim 8, characterized in that the first seat plate is provided with a receptacle structure and the second seat plate is provided with a ball structure, and the ball structure seats inside. of the receptacle structure for joining said plates.
10. 10. A drilling mud grille of a rig seaborne rigid floating device, the drill mud grille comprising: • first and second seat plates joined together, wherein the first seat plate is provided with a structure of receptacle and the second seat plate is provided with a ball structure, and the ball structure seats within the receptacle structure to join the plates in order to form the corrugated plate surface. Frame members that are attached to and provide support to said at least one base plate, the frame members comprising a base plate support structure, the frame members comprising a base plate support structure, support structure comprising full core beam means, and at least one plate joining flange attached to the full core beam means, wherein at least one of the first and second seat plates are attached to the plate joining tab; and Where the seat plates are formed of plastic. The drilling mud grid according to claim 10, characterized in that the seating plates are formed of polyvinyl chloride 12. The drilling mud grid according to claim 10, characterized in that the seating plates are formed of resin reinforced with particles