Abstract:
A configurable, multi-function vessel that comprises first and second pontoon barges and a plurality of interconnecting barges. The first and second pontoon barges have a plurality of connection members disposed on the inboard sides thereof. The plurality of interconnecting barges are disposable between the inboard sides of the first and second pontoon barges so that a plurality of connection members disposed on opposite sides of the interconnecting barges are adjacent to the connection members on either said first or second pontoon barge. A plurality of connectors releasably couple adjacent connection members so that the pontoon barges and the interconnecting barges form a unitary, oceangoing vessel.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    Not applicable. 
       STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0002]    Not applicable. 
       BACKGROUND OF THE INVENTION 
       [0003]    The invention relates to systems for installing offshore equipment and supporting offshore operations. More specifically, embodiments of the present invention relate to configurable vessels for installing offshore equipment used in the exploration and production of hydrocarbons. 
         [0004]    Offshore systems used in the exploration and production of oil and gas reservoirs are large complicated structures that require a number of specialized operations to be performed during the installation process. These installation operations involve precise positioning of heavy loads in an inherently unstable offshore environment that requires vessels to possess good hydrodynamic performance in order to safely and successfully perform the operations. Because, of the variety of installation operations that need to be performed and the high capital costs of the required vessels, installation companies typically consider the full range of possible jobs that can be performed and select large, general-purpose vessels. 
         [0005]    These large, general-purpose vessels generally command high daily rental rates in order to cover the expenses involved in building and operating the vessels. Therefore, many owners prefer to keep the vessels in operation so that their utilization rate is as high as possible. Given the weather and sea-state sensitivities involved in offshore operations, there are often long periods of unplanned downtime, which, when combined with the high planned utilization rate, result in significant delays to projects that are currently being executed as well as all projects that are in backlog. 
         [0006]    The capabilities of the installation vessel to be used on a project are very important for project planning because there are very few vessels that can do large deepwater projects. For example, any one market may only have one or two installation vessels at any time. Therefore, all large-scale projects must be designed around the capabilities of the vessels available. For example, in the design of an offshore production platform, the available installation vessel&#39;s capabilities will typically drive the structural design of the topsides deck, the systems used for maneuvering the hull, and the components of both the mooring and riser systems. 
         [0007]    Although a large, general-purpose installation vessel can perform many common installation operations, some of these operations could alternatively be performed by other, more efficient vessels, reserving the large, general-purpose vessels for those functions that actually require the capabilities of the larger installation vessel. Building smaller, purpose-built installation vessels is also problematic as the utility of these vessels may be limited, making the economics difficult to justify. 
         [0008]    One of the most important drivers for large projects is whether or not a topsides lift is needed. Lifting topsides often requires a very large derrick barge, which are limited in number and therefore may be difficult to schedule. Installation of the topsides using a float-over procedure eliminates the need for a topsides lift by transporting the topsides on a barge to a floating hull. The floating hull is partially sunk so that the topsides can be floated over the hull into position. One issue with using a float-over procedure is that the barges used to transport the topsides often have to be specially constructed for a particular project, making their use prohibitively expensive. 
         [0009]    Thus, the embodiments of the present invention are directed embodiments of to a modular, configurable system that can support a variety of installation operations that seek to overcome these and other limitations of the prior art. 
       SUMMARY OF THE PREFERRED EMBODIMENTS 
       [0010]    Embodiments of the present invention include a configurable, multi-function vessel that comprises first and second pontoon barges and a plurality of interconnecting barges. The first and second pontoon barges have a plurality of connection members disposed on the inboard sides thereof. The plurality of interconnecting barges are disposable between the inboard sides of the first and second pontoon barges so that a plurality of connection members disposed on opposite sides of the interconnecting barges are adjacent to the connection members on either said first or second pontoon barge. A plurality of connectors releasably couple adjacent connection members so that the pontoon barges and the interconnecting barges form a unitary, oceangoing vessel. 
         [0011]    Thus, the embodiments of present invention comprise a combination of features and advantages that enable a single vessel to be provided in a plurality of configurations to support multiple activities. These and various other characteristics and advantages of the present invention will be readily apparent to those skilled in the art upon reading the following detailed description of the preferred embodiments of the invention and by referring to the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    For a more detailed understanding of the present invention, reference is made to the accompanying Figures, wherein: 
           [0013]      FIG. 1  illustrates the components of a configurable multi-function vessel constructed in accordance with embodiments of the present invention; 
           [0014]      FIGS. 2 and 3  illustrate a connection member and connector constructed in accordance with embodiments of the present invention 
           [0015]      FIG. 4  shows a multi-function vessel in a first configuration for use in the installation of a topsides or module/hull floatoff 
           [0016]      FIG. 5  shows a multi-function vessel being used in the float-over installation of a topsides on a semi-submersible hull; 
           [0017]      FIG. 6  shows a multi-function vessel in a second configuration for use in the installation of a topsides or launching of a spar-type hull; 
           [0018]      FIG. 7  shows the multi-function vessel of  FIG. 6  being used in the float-over installation of a topsides on a semi-submersible hull; 
           [0019]      FIG. 8  shows the multi-function vessel of  FIG. 6  being used in the launching of a spar-type hull; 
           [0020]      FIG. 9  shows a multi-function vessel third configuration for use in the installation of a topsides; 
           [0021]      FIG. 10  shows the multi-function vessel of  FIG. 9  being used in the float-over installation of a topsides on a spar-type hull; 
           [0022]      FIG. 11  shoes a multi-function vessel in a fourth configuration for supporting the installation of subsea equipment; 
           [0023]      FIG. 12  shows the multi-function vessel of  FIG. 11  being utilized as to install subsea wellheads; and 
           [0024]      FIG. 13  shows the multi-function vessel of  FIG. 11  being utilized as to install subsea suction anchors and mooring components; 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0025]    In the description that follows, like parts are marked throughout the specification and drawings with the same reference numerals, respectively. The drawing figures are not necessarily to scale. Certain features of the invention may be shown exaggerated in scale or in somewhat schematic form and some details of conventional elements may not be shown in the interest of clarity and conciseness. 
         [0026]    The preferred embodiments of the present invention relate to apparatus for facilitating the installation of offshore and subsea equipment. The present invention is susceptible to embodiments of different forms. There are shown in the drawings, and herein will be described in detail, specific embodiments of the present invention with the understanding that the present disclosure is to be considered an exemplification of the principles of the invention, and is not intended to limit the invention to that illustrated and described herein. In particular, various embodiments of the present invention provide vessels used in the installation of offshore and subsea oilfield equipment, but the use of the concepts of the present invention is not limited to these applications, and can be used for any other applications including other offshore and maritime applications. It is to be fully recognized that the different teachings of the embodiments discussed below may be employed separately or in any suitable combination to produce desired results. 
         [0027]    Referring now to  FIG. 1 , a configurable vessel  10  comprises a first pontoon barge  12 , a second pontoon barge  14 , and a plurality of interconnecting barges  16 . The pontoon barges  12  and  14  each have a plurality of connecting members  18  disposed on their respective inboard sides  20 . Each interconnecting barge  16  has connecting members  18  disposed on each side. The connecting members  16  allow the pontoon barges  12  and  14  to be assembled with interconnecting barges  16  in a variety of configurations so that vessel  10  can be used in support of multiple installation operations, examples of which will be discussed in detail below. 
         [0028]    Pontoon barges  12  and  14  are generally rectangular cross-sectioned barges having a length several times greater than the beam. In certain embodiments, pontoon barges  12  and  14  have a length of 450 feet and a beam of 40 feet. Interconnecting barges  16  are substantially smaller than pontoon barges  12 ,  14  but have a similar rectangular cross-section and internal structural framing. In certain embodiments, interconnecting barges  16  have a length of 100 feet and a beam of 40 feet. 
         [0029]    A plurality of connecting members  18  are disposed along the inboard sides  20  of pontoon barges  12  and  14  and all sides of interconnecting barges  16 . Connecting members  18  are either integrally formed or securely tied into the internal structural framing of the barge, providing a mechanism that allows pontoon barges  12  and  14  and interconnecting barges  16  to be assembled into a vessel that is suitable for use in offshore environments. 
         [0030]    Barges  12 ,  14 , and  16  are coupled together by a connection system that is sufficiently robust to enable offshore operations as well as being easy to engage and disengage so as to enable a truly flexible and configurable system.  FIGS. 2 and 3  illustrate one embodiment of a connection system comprising connecting members  18 , bolts  19 , and shear pin  21 . As discussed above, connecting members  18  extend from the sides of the barges and each connecting member comprises a flange  23  that is substantially parallel to the side of the barge. Each flange  23  comprises upper and lower bolt patterns  25  and shear pin receptacle  27 . Bolts  19  and shear pin  21  comprise connectors  29  that couple adjacent connecting members  18 . Bolts  19  act primarily at tension members while shear pins  19  support shear loads. Thus, the combination of bolts  19  and shear pins  21  resist both tension and shear loading so that adjacent barges are securely connected to one another. Those who are skilled in the art will realize that the bolting and pin system that is described could be replaced with other connection systems, such as those used to connect tugs and barges during oil lightering operations. 
         [0031]    Thus, it can be seen that pontoon barges  12  and  14  and interconnecting barges  16  can be assembled into a number of different configurations in order to support a variety of offshore functions. Once such configuration is shown in  FIG. 4  where interconnecting barges  16  are disposed between, and oriented parallel with, pontoon barges  12  and  14 . Adjacent interconnecting barges  16  are coupled to each other and to pontoon barges  12  and  14  so as to form vessel  22  that is suited for carrying heavy loads, such as a topside structure, for installation as an offshore platform. 
         [0032]    Vessel  22  is especially well suited for the float-over installation of a topsides  24  onto a partially submerged semi-submersible hull  26 , as is shown in  FIG. 5 . Topsides  24  is placed onto vessel  22  and transported to semi-submersible hull  26 . Semi-submersible hull  26  is lowered in the water using the hull&#39;s ballast control systems and vessel  22  moved between the legs of the semi-submersible until topsides  24  is in the proper position. Once properly positioned, hull  26  is raised to lift topsides  24  off of vessel  22 . 
         [0033]    As can be seen in  FIG. 5 , in order to perform a float-over installation, vessel  22  must be able to fit between the legs of semi-submersible hull  26 . Therefore, either the beam of the vessel used is limited by the spacing of the hull&#39;s legs or the spacing of the legs is determined by the size vessel that is available and able to transport the topsides. In order to provide a vessel having a minimum beam, pontoon barges  12  and  14  can be directly connected to each other to form vessel  28 , as shown in  FIG. 6 . Referring now to  FIG. 7 , vessel  28  can be utilized in float-over operations to install topsides  30  onto hull  32 . Vessel  28  can also be used to launch or transport other equipment for offshore installation. As an example,  FIG. 8  shows vessel  28  being used to launch or transport a spar hull  34 . 
         [0034]    The float-over installation of a topsides structure onto a spar-type hull, or other mono-column or closely spaced structure, requires the use of two vessels so that the center portion of the topsides is available for attachment to the hull. In order to support float-over installations on spar-type hulls, modular system  10  can be configured into vessel  36  as shown in  FIG. 9 . 
         [0035]    Referring now to  FIG. 9 , vessel  36  comprises interconnecting barges  16  disposed between pontoon barges  12  and  14  so that the longitudinal axes of the interconnecting barges are perpendicular to the longitudinal axes of the pontoon barges. This arrangement provides a wide beam for vessel  36  and a large open bay  38  at the front of the vessel. Referring now to  FIG. 10 , topsides  40  is disposed on vessel  36  above open bay  38 . Vessel  36  moves topsides  40  over a partially submerged hull  42  that is then raised to support the topsides, which can then be removed from the vessel. 
         [0036]    In addition to being used for the transport of heavy loads such as topsides and other structures for offshore installation, system  10  can also be configured as an independent support vessel to be used in the installation of other subsea equipment. Referring now to  FIG. 11 , vessel  44  comprises interconnecting barges  16  disposed between and parallel with pontoon barges  12  and  14 . Interconnecting barges  16  are spaced apart to form a moon pool  46  in the middle of vessel  44 . 
         [0037]      FIGS. 12 and 13  illustrate two possible uses of vessel  44 , where the vessel has been equipped with modular thrusters  48 , a lifting/lowering system  50 , and crew quarters  52 . Modular thrusters  48  are positioned on each corner of vessel  44  and provide the controllable, directional thrust needed to propel and position the vessel during installation operations. Lifting/lowering system  50  is disposed adjacent to moon pool  46  and may be a winch or derrick-based system that can be used to lower equipment to the seafloor. Crane  54  may also be positioned on vessel  44  to aid in handling and moving equipment. Crew quarters  52  provide operational and berthing areas for the personnel needed to operate vessel  44 . 
         [0038]    Referring now to  FIG. 12 , vessel  44  is shown being used in the installation of subsea wellhead modules  56 . Vessel  44  provides a large amount of deck space for storing multiple modules  56  as well as large diameter pipe  58  and other materials needed for the installation of the modules subsea.  FIG. 13  shows vessel  44  being used in the installation of subsea suction anchors  60  that are commonly used in offshore mooring applications. As a typical mooring application will use many anchors, the large deck space of vessel  44  allows the vessel to install several anchors without being re-supplied, therefore reducing the time needed to install all of the anchors for a given system. 
         [0039]    As can be seen in the above examples, configurable system  10  provides a plurality of vessel configurations that allow a single system to support a number of different installation and maintenance operations. Because a single system can be easily reconfigured and adjusted to meet the needs of a particular project, system  10  provides an economical alternative to both single-purpose vessels and large, general-purpose installation vessels. The vessel configurations described are merely examples of how system  10  could be utilized. Those skilled in the art would recognize other configurations and uses. 
         [0040]    The embodiments set forth herein are merely illustrative and do not limit the scope of the invention or the details therein. It will be appreciated that many other modifications and improvements to the disclosure herein may be made without departing from the scope of the invention or the inventive concepts herein disclosed. Because many varying and different embodiments may be made within the scope of the inventive concept herein taught, including equivalent structures or materials hereafter thought of, and because many modifications may be made in the embodiments herein detailed in accordance with the descriptive requirements of the law, it is to be understood that the details herein are to be interpreted as illustrative and not in a limiting sense.