Abstract:
An apparatus for loading a topside onto a jacket is provided. The apparatus may include: a projecting structure extending beyond a deck of a marine vessel wherein the projecting structure configured to support the topside and the projecting structure is dimensioned sufficiently long enough to allow the marine vessel to approach a submerged jacket and position the topside above the submerged jacket without having the marine vessel contact the jacket; and a support configured to support the topside above the projecting structure. A method for one of installing and removing a topside from a jacket may be provided. The method may include: positioning sponsons attached to a marine vessel around a jacket; supporting at least part of the weight of the topside on the sponsons; and one of attaching and detaching the topside and jacket.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates generally to a method and apparatus for loading heavy offshore oiling equipment onto a submerged support such as a jacket. More particularly, the present invention relates to a method and apparatus for loading a topside onto and/or off a jacket. 
       BACKGROUND OF THE INVENTION 
       [0002]    As the demand for oil continues to increase, more and more oil fields are being identified as beneath the ocean floor. Traditionally, with offshore oil production platforms, either fixed or floaters, the topsides are installed to the substructures, jackets or hull, by a specially designed heavy lifting vessel such as a crane vessel. However, the use of heavy lifting vessels presents a variety of challenges including the reliability of being able to safely lift heavy structures, the availability of vessels capable of lifting required amounts of weight. Strict environmental requirements can create narrow weather windows in which operations may be done. High operational costs of using lifting vessels have encouraged the oil gas exploration and production industry to look for alternative ways to load heavy structures onto platforms. 
         [0003]    For over the past several years, a technique referred to as the float-over topside installation technique has gradually gained momentum. It has not only been used in topside installation for fixed platforms already installed at the oil field, but has been used for floating support structures in both in-shore and offshore applications. 
         [0004]    Float-over installation does not require the use of a heavy lifting vessel and therefore omits the challenging lifting operation. Only selected barges equipped with specially designed equipment are used in float-over operations. The technology is mature and the cost is relatively low compared to using heavy lifting vessels. Furthermore, float-over techniques can require shorter time and the weather window for performing such operations is wider than what is required in heavy lifting techniques. 
         [0005]    However, the use of float-over technology is not without its drawbacks. Under current float-over techniques, when using a single barge or vessels for a fixed platform, there should be an opening wide enough between the legs of the jacket so that the barge carrying the topside can float in between the jacket legs. The barge will then move over and let the topside reach the position aligning with the jacket legs to prepare the jacket for the mating operating between the topside of the jacket. If there is not room for the barge to fit between the jacket legs, float-over operation can also be carried out using two barges where the barges are configured in a catamaran-type configuration. However, this is not favored for small platforms since the advantages of cost-efficiency disappear. 
         [0006]    Many newer design jackets may have a wide opening between the jacket legs in order to accommodate the single barge float-over technique. However, many older jackets or ones that are traditionally designed may not have legs wide enough to accept the single barge. As such, they present additional difficulties in using a single barge or vessel with the float-over technique. Accordingly, it is desirable to provide a method and apparatus that can be used to more easily attach a topside to a similar structure such as a jacket. 
       SUMMARY OF THE INVENTION 
       [0007]    The foregoing needs are met, to a great extent, by the present invention, wherein in one aspect an apparatus is provided that in some embodiments a method and apparatus is described that provides a new way to attach a topside to a substructure such as a jacket. 
         [0008]    In accordance with one embodiment of the present invention, an apparatus for loading a topside onto a jacket is provided. The apparatus may include: a projecting structure extending beyond a deck of a marine vessel wherein the projecting structure configured to support the topside and the projecting structure is dimensioned sufficiently long enough to allow the marine vessel to approach a submerged jacket and position the topside above the submerged jacket without having the marine vessel contact the jacket; and a support configured to support the topside above the projecting structure. 
         [0009]    In accordance with another embodiment of the present invention, a method for one of installing and removing a topside from a jacket may be provided. The method may include: positioning sponsons attached to a marine vessel around a jacket; supporting at least part of the weight of the topside on the sponsons; and one of attaching and detaching the topside and jacket. 
         [0010]    In accordance with yet another embodiment of the present invention, a method for one of installing and removing a topside from a jacket may be provided. The method may include: locating a support beam proximate to the jacket; moving the topside along the support beam; and one of attaching and detaching the topside and the jacket. 
         [0011]    There has thus been outlined, rather broadly, certain embodiments of the invention in order that the detailed description thereof herein may be better understood, and in order that the present contribution to the art may be better appreciated. There are, of course, additional embodiments of the invention that will be described below and which will form the subject matter of the claims appended hereto. 
         [0012]    In this respect, before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and to the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of embodiments in addition to those described and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein, as well as the abstract, are for the purpose of description and should not be regarded as limiting. 
         [0013]    As such, those skilled in the art will appreciate that the conception upon which this disclosure is based may readily be utilized as a basis for the designing of other structures, methods and systems for carrying out the several purposes of the present invention. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]      FIG. 1  is a side view illustrating an apparatus for installing a topside onto the jacket. 
           [0015]      FIG. 2  is a side view illustrating a topside and skid beam attached to a barge. 
           [0016]      FIG. 3  is a side view illustrating a topside and skid beam located adjacent to a jacket. 
           [0017]      FIG. 4  is a side view illustrating a topside moved into position over a jacket. 
           [0018]      FIG. 5  is a side view of a topside attached to a jacket where a barge is moving away from the jacket. 
           [0019]      FIG. 6  is a perspective view of a barge in position approximate to a jacket where a topside is being moved in position over the jacket. 
           [0020]      FIG. 7  is partial side view of a topside float-on to a structure on a barge. 
           [0021]      FIG. 8  is an end view of a topside loaded onto the barge. 
           [0022]      FIG. 9  is a side view of a barge with sponsons located next to a jacket. 
           [0023]      FIG. 10  is end view of a topside located over a jacket where the topside is still attached to sponsons. 
           [0024]      FIG. 11  is a side view of a topside loaded onto sponsons. 
           [0025]      FIG. 12  is a side view of a vessel located near a jacket and a topside located in position over the jacket. 
           [0026]      FIG. 13  is a side view of vessel located next to a jacket on the topside which is connected with the jacket. 
           [0027]      FIG. 14  is a side view of a vessel moving away from a jacket having a topside installed onto the jacket. 
           [0028]      FIG. 15  is a perspective view of one of the designs of the supporting frame. 
           [0029]      FIG. 16  is a side view of a skid shoe. 
           [0030]      FIG. 17  is a perspective view of a skid beam. 
           [0031]      FIG. 18  is a perspective view of a vessel having sponsons supporting a topside. 
           [0032]      FIG. 19  is a partial perspective view of a topside mounted to sponsons located over a jacket. 
           [0033]      FIG. 20  illustrates a method for installing a topside onto a jacket. 
           [0034]      FIG. 21  illustrates a method for removing a topside from a jacket. 
           [0035]      FIG. 22  illustrates another method for installing a topside onto a jacket. 
           [0036]      FIG. 23  illustrates another method for removing a topside from a jacket. 
       
    
    
     DETAILED DESCRIPTION 
       [0037]    The invention will now be described with reference to the drawing figures, in which like reference numerals refer to like parts throughout. An embodiment in accordance with the present invention provides a method and apparatus for loading a topside onto a jacket or other similar structure and also unloading a topside from a jacket. In some embodiments, the installation and removal techniques may be used for fixed platform topsides weighing up to 4000 mt. 
         [0038]    The apparatus and methods described herein fall primarily within two embodiments using skid-on techniques. In a first embodiment, a pair of skid beams are used to carry the topside over the jacket legs. In the other embodiments, sponsons are attached to a barge or other vessel and extend out of from the barge or vessel. In the embodiments, the skid beams or the sponsons carry the topside over the jacket legs. The mating process of the topside to the jacket legs is similar to that used in the known float-over at site techniques. 
         [0039]    In the reverse process, in accordance with an embodiment of the invention, the skid-on technology can be applied to the topside removal. After reading the disclosure made herein one of ordinary skill in the art can using a case-by-case basis and examining the different facts of each particular application may be selected from one of the two options, the skid beam or the sponsons to attach or detach a topside and jacket. Skid beam techniques and sponsons techniques will be described below. 
         [0040]      FIG. 1  shows a skid beam system  30  used in accordance with the skid beam technique for attaching and detaching a topside  32  to the jacket  34 . The topside  32  is the structure that is often located above the waterline  40  at an offshore platform. The topside  32  usually sits upon pre-installed structure referred to herein as a jacket  34 . The jacket  34  and topside  32  are well known in the industry and will not be described in additional detail. The application herein refers generally to a jacket  34  as a submerged structure which supports the topside  32 . One of ordinary skill in the art will appreciate that topside  32  may be attached to other structures such as floating structures well known in the industry that may perform the function of supporting the topside  32  as that of a jacket  34  attached to the sea floor  38  as shown. Thus, the term jacket  34  as used here is only meant to relate generally to a support structure and is not limited to those types of support structures that have legs  36  which attach directly to the sea floor  38 . 
         [0041]    As shown in  FIG. 1 , part of the jacket  34  may extend a little bit above the waterline  40  which connects to the connecting structure  42  of the topside  32 . A barge  44  or other water borne vessel may have a supporting frame  46  attached to the deck  47  of the barge  44 . The terms “barge” and “vessel” will be used interchanged herein. The barge  44  may be a heavy lifting barge with at least 10,000 DWT with ballast systems. The ballast system will permit the barge  44  to be raised or lowered with respect to the waterline  40  or by ballasting the barge  44  up or down. The deck weight may be at least 4,000 mt. The supporting frame  46  supports the topside  32  while the topside is attached to the barge  44 . The topside  32  will be attached and supported by the supporting frame  46  in a sea fasten manner in order to allow the barge  44  to transport the topside  32  to in-shore or offshore sites where the jacket  34  is located. 
         [0042]    The supporting frame  46  may be topped with a skid beam  48 . The skid beam  48  may be an elongated structure or assembly rather than a single beam that extends out beyond the barge  44 . A skid shoe  50  is mounted to the top of the skid beam  48 . The topside  32  is attached to the skid shoe  50 . The skid shoe  50  is configured to skid along the skid beam  48  thus enabling the topside  32  to move along the skid beam  48 . A cable winch and pulley system  51  may be attached to the barge  44  and the topside  32  and may be configured to move the topside  32  on the skid shoe  50  along the skid beam  48  in a desired manner Other systems may also be used to move the topside  32  along the skid beam  48 . 
         [0043]    Once the barge  44  is positioned and is at a desired location with the respect to the jacket  34 , the topside  32  may be moved via the cable winch and pulley system  51  along the skid beam  48  extending over the jacket  34 . The barge or vessel  44  may be ballasted to move up or down in the water  54  in order to provide a desired vertical location of the topside  32 . When the top side  32  is positioned over the jacket  34 , the vessel  44  is high in the water to allow the topside  32  to be moved in position. The vessel  44  may then be ballasted to ride lower in the water  54  so that the topside  32  touches the jacket legs  36  enabling the topside  32  to be attached to the legs  36  according to well-known techniques similar to those used in float-over techniques. 
         [0044]    In some embodiments, the technique of using mating cones and cups will be employed to assist in the connecting of the connecting structure  42  of the topside  32  and the legs  36  of the jacket  34 . 
         [0045]    Once the topside  32  is attached to the jacket  34  the finished structure  52  is formed as seen for example in  FIG. 5 . 
         [0046]    In some embodiments in accordance with the invention and as shown in  FIG. 1 , if a topside  32  is particularly heavy, a second barge  56  may be used. The second barge  56  is shown in dashed lines to indicate that it is optional. The second barge  56  may include a support column  58  to support the cantilevered end of the skid beam  48 . In other embodiments of the invention, as shown in  FIGS. 2-5 , only a single barge  44  or vessel is used. 
         [0047]    As shown in  FIG. 2 , the vessel  44  is loaded with a supporting frame  46  and between the supported frame  46  and the topside  32  is the skid shoe  50 . The skid beam  48  extends past the barge  44  and is therefore capable of extending over the jacket  34  as shown in  FIG. 1 . The topside  32 , the skid beam  48  and the supporting frame  46  are sea fastened to the barge  44  so they will not shift as the barge  44  moves over the water  54 . The vessel  44  may be ballasted so that waterline  40  is at its desired location with respect to the vessel  44 . 
         [0048]    As shown in  FIG. 3 , the vessel  44  moves to a desired position with respect to the jacket  34 . In most instances, this desired location will be where the skid beam  48  extends over the legs  36  of the jacket  34 . The jacket  34 , as shown in  FIG. 3 , may be attached to the sea floor  38 . In other embodiments of the invention, mating legs similar to the legs  36  may be attached to a submerged floating structure as known in the art. 
         [0049]    At this point, the barge or vessel  44  may be ballasted to ride high in the water  54 . The skid shoe  50  and topside  32  are located over the supporting frame  46 . The topside  32  may be moved along the skid beam  48  by use of a cable winch and pulley system  51  (see  FIG. 1 ) or other suitable system. The topside  32  is mounted on the skid shoe  50  which enables movement of the topside  32  along the skid beam  48 . The connecting structure  42  is aligned with the legs  36  on the jacket  34 . At this point, the supporting frame  46  may still be supporting the weight of the topside  34  and the vessel  44  may be ballasted to place the connecting structure  42  in contact with the legs  36  and the jacket  34 . 
         [0050]    Once the topside  32  is connected to the legs  36  of the jacket  34 , the skid shoes  50  are detached with the topside  32  through mechanical action or ballasting the vessel  44  and the vessel  44  along with the supporting frame  46 , the skid beam  48 , and the skid shoe  50  may move away from the resultant finished structure  52  as shown in  FIG. 5 . The finished structure  52  may be comprised of the topside  32  and the connecting structure  42  connecting the topside  32  to the legs  36  of the jacket  34 . 
         [0051]      FIGS. 6-7  illustrate a perspective view and a partial view of the topside  32  located on the skid shoe  50  on the skid beam  48  being supported by the supporting frame  46 . The vessel  44  is shown with respect to the waterline  40  as supported by the water  54 .  FIG. 6  illustrates the jacket  34  being supported by the sea floor  38 .  FIG. 8  shows an end view of the skid beam system  30 . The barge or vessel  44  is shown with respect to the waterline  40 . Upon the barge or vessel  44  is the supporting frame  46  supporting to the topside  32 . The connecting structure  42  is also illustrated. 
         [0052]      FIGS. 9-14  and  18 - 19  illustrate a sponson system  60  in accordance with another embodiment of the invention. In the sponson system  60 , as shown in  FIG. 9 , the topside  32  is supported by sponsons  62  attached to the vessel  44 . The sponsons  62  may be attached to the interior frame of the vessel  44  as well as the vessel  44  hull. The sponsons  62  are attached in a manner to allow the sponsons  62  to support the weight of a topside  32 . The vessel  44  and sponson  62  are shown with respect to the waterline  40  and are floating in the water  54 . The topside  32  is positioned over the jacket  34  supported by the sea floor  38 . 
         [0053]      FIG. 10  is an end view similar to that shown in  FIG. 9 . In  FIG. 10 , the sponsons  62  are shown supporting the topside  32  with a supporting frame  46 . In some embodiments, the distance between the sponsons  62  may be adjusted. Preferably, the width of the hull stern should be large enough to permit the jacket to fit in the open space between the two sponsons  62  attached to the two side shells of the vessel  44 . 
         [0054]    The supporting frame  46  is attached to and rests upon the sponsons  62 . The topside  32  has been positioned over the jacket  34 . In some embodiments, the longitudinal dimension of the jacket  34  is near  40  meters near the water surface elevation. Each sponson  62  can be  80  meters long with  40  meters extending from the hull stern of the vessel  44 . 
         [0055]      FIG. 11  is a side view of the sponson system  60  showing the vessel  44  with sponson  62  which support the topside  32  approaching the topside  34 . The legs  36  of the jacket  34  are also shown. The topside  32  is supported by a supporting frame  46  and a connecting structure  42  is shown the connection structure  42  well attached to the legs  36 . 
         [0056]      FIG. 12  illustrates the vessel  44  aligned with jacket  34  so the connecting structure  42  of the topside  32  is aligned with the legs  36  of the jacket  34 . The vessel  44  has been ballasted so that the topside  32  is above and therefore clears the legs  36  of the jacket  34 . The topside  32  is supported by the sponsons  62  attached to the vessel  44 . 
         [0057]      FIG. 13  illustrates a topside  32  that has been lowered so that the connecting structure  42  contacts that legs  36  of the jacket  34 . The topside  32  may be lowered by ballasting the barge  44  down or by lowering the topside  32  with a lowering system that may include jacks. In some embodiments of the invention both jacks and a barge  44  capable of ballasting up or down may be used. The connecting structure  42  connects to the legs  36  of the jacket  34 . In embodiments where the topside  32  is lowered solely by ballasting the vessel  44  there is no relative movement between the topside  32  and the vessel  44  before and during the mating process of attaching the topside  32  to the jacket  34 . 
         [0058]      FIG. 14  shows the vessel  44  moving away from the finished structure  52 . Finished structure  52  is comprised of the topside  32 , the connection structure and the jacket  34 . The vessel  44  has been de-ballasted so that it sits higher in the water  54  than that shown in  FIG. 13 . The sponsons  62  support the supporting frame  46 . The topside  32  is supported by the jacket  34 . The construction of the finished structure  52  is now being completed using the sponson system  60 . 
         [0059]      FIG. 15  is a perspective view of an example supporting frame  46  that may be used in a skid beam type system  30  and shown in  FIGS. 1-8 . The supporting frame  46  may include a top  74  and bottom  76 . The bottom  76  may attach to the vessel  44  while the top  74  attaches to the skid shoes  50  which support the topside  32  (the vessel  44 , skid shoes  50  and the topside  32  are not shown in  FIG. 15 ). The supporting frame  46  may be built of small units so that more or less units may be used to adjust the height of the topside  32  to a desired height. The desired height may be related to a desired gap between the connecting structure  42  and the legs  36  of the jacket  34  during a mating operation. 
         [0060]      FIG. 16  shows a side view of a skid shoe  50  that may be used in accordance with the invention. Skid shoe  50  may include a contacting frame  66  and reduced friction element  68  which are in context with the skid beam  48  to facilitate movement of the skid shoe  50  across the skid beam  48 . 
         [0061]      FIG. 17  is an example perspective view of a skid beam  48  that may be used in accordance with an invention. The skid beam  48  may include a supported portion  70  and cantilever portion  72 . The portion of the cantilever portion  72  that hangs over the side of the vessel  44  may be about  20  meters long. Cantilevered portions  72  of other lengths may also be used. The supported portion  70  may be attached to the supporting frame  46  shown for example in  FIG. 15 . 
         [0062]      FIGS. 18-19  are perspective views of a sponson system  60 .  FIG. 19  is an enlarged partial view similar to that shown in  FIG. 18 . As shown in  FIGS. 18-19 , the vessel  44  is equipped with sponsons  62  supporting a topside  32 . The sponsons  62  have support frames  46  supporting the topside  32 . Optionally, multiple supporting frames  46  may be used. Support frames  46  that are large and configured to support the topside  32  may be mounted to each sponson  62 . 
         [0063]    The sponsons  62  may provide buoyancy to make the deck weight load better distributed on the barge hull. If more buoyancy is desired, the sponsons  62  may also include buoyancy boxes  64  which increase the buoyancy and therefore lifting capability of the sponsons  62 . Buoyancy boxes  64  may be desirable particularly in instances where the topside  32  is particularly heavy. 
         [0064]    One of ordinary skill in art may, after review of this disclosure, select an appropriate amount or size of buoyancy boxes  64  to attach to the sponson  62  as needed in individual applications. 
         [0065]    As shown in  FIG. 18 , the topside  32  is approaching the jacket  34 . The legs  36  of the jacket  34  extend upwardly and are exposed to receive the connecting structure  42 . As shown in  FIG. 19 , the vessel  44  has moved in position so that the sponsons  62  are on either side of the jacket  34  and the connecting structure  42  is located just above the legs  36  of the jacket  34 . Once the connecting structure  42  is aligned with the legs  36 , the topside  32  can be lowered by either ballasting the vessel  44  down or lowering the topside  32  if the supporting frame  46  incorporates jacks or other structure which allows the topside  32  to be lowered. In instances where the supporting frame  46  is of a fixed height then the topside  32  may be lowered by ballasting the vessel  44  down. 
         [0066]      FIG. 20  illustrates the steps that may be used in a method for attaching a topside to a jacket using the skid beam method. In step S 30 , operators will assemble supporting frames, skid beams and skid shoes and load them on the vessel. At step S 32 , the operators load the topside on the skid beam at a location on the skid beam for transportation and sea fasten the topside to the vessel. At step S 34  the operators move the vessel to a desired position. At step S 36  the operators align the vessel with an installed jacket. As mentioned above, the jacket may be a supporting structure for the topside that attaches the sea floor or in other embodiments, of the invention, it may be a floating structure. At step S 38 , operators align the vessel to desired vertical position or, in other embodiments, may laterally move the topside up or down to a desired position. At step S 40  operator slides topside across the skid beam into position over the jacket. At step S 42  operators connect topside to the jacket. At step S 44  the operators disconnect the topside from the skid beam and vessel. At step S 46  the operators move the vessel away. One of ordinary skill in the art after reviewing this disclosure will note that the steps set forth in  FIG. 20  need not necessarily be conducted in the order indicated. 
         [0067]      FIG. 21  illustrates steps an operator may do to remove a topside from a jacket using a skid beam type method. As shown in  FIG. 21  at step S 48 , the operator assembles support beams, skid beams and skid shoes onto a vessel. At step S 50  operators move vessel into position near the topside in jacket and ballast the vessel to a desired vertical position. At step S 52 , the operator attaches the topside to the skid shoe(s). At step S 54 , the operator cuts the jacket legs to release the topside from the jacket. At step S 56  the operator skids the topside across the skid beam to a position for transport. At S 58  the operator sea fastens the topside to the vessel. At step S 60  the operators move vessel away from the jacket. 
         [0068]      FIG. 22  illustrates a method of attaching a topside to a jacket using a sponson method. At step S 62 , the operators attach sponsons to the vessel. At step S 64  the operators assemble supporting frames and load them on the vessel. At step S 66 , operators load topside onto the sponson or vessel deck upon the supporting frames and sea fasten the topside to the vessel. At step S 68 , the operators move vessel to position and align vessel with the installed jacket. At step S 70 , the operators ballast the vessel to achieve a desired vertical position of the topside. In other embodiments of the invention, the topside may be moved vertically and at S 72  operators move the topside to sponsons if the topside was located on the deck. At step S 74 , the operators ballast the vessel to a desired vertical position so the topside is over the jacket. At step S 76 , operators connect the topside to the jacket. At step S 78 , the operators move the vessel away. 
         [0069]      FIG. 23  illustrates a method of removing a topside from a jacket using a sponson method in accordance with an embodiment of the invention. At step S 80 , the operators assemble supporting structures on the sponson and/or deck of the vessel. At step S 82 , the operators move the vessel in position near the topside. At step S 84 , the operators ballast the vessel to a desired vertical position. At step S 86 , the operators attach topside to supporting structures on the vessel and cut the jacket legs to release the topside from the jacket. At step S 88 , the operators move the topside from the jacket and sea fasten the topside to the vessel. At step S 90 , the operators move the vessel away from the jacket. 
         [0070]    The many features and advantages of the invention are apparent from the detailed specification, and thus, it is intended by the appended claims to cover all such features and advantages of the invention which fall within the true spirit and scope of the invention. Further, since numerous modifications and variations will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation illustrated and described, and accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope of the invention.