Abstract:
A subsea platform transporter includes a plurality of pontoon members, a plurality of column members interconnecting select adjacent ones of the plurality of pontoon members forming a support frame having an inner platform receiving area, a plurality of buoyancy members mechanically linked to at least one of the plurality of pontoon members and the plurality of column members, and a plurality of platform retaining members mounted to one or more of the plurality of pontoon members and the plurality of column members about the inner platform receiving area. The plurality of platform retaining members is configured and disposed to selectively retain and release a platform supported by the subsea platform transporter.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a non-provisional application which claims benefit under 35 USC §119(e) to U.S. Provisional Applications Ser. No. 61/902,409 filed Nov. 11, 2013, entitled “SUBSEA PLATFORM TRANSPORTER (SPT)” which is incorporated herein in their entirety. 
     
    
     FIELD OF THE INVENTION 
       [0002]    This invention relates to a subsea platform transporter. In another aspect, the invention concerns a subsea platform transporter having a subsea system mounted to a subsea platform. In another aspect, the invention concerns a system for transporting a fully integrated and onshore tested subsea system to a sea floor location. In another aspect, the invention concerns a system for transporting a subsea drilling rig to the sea floor. 
       BACKGROUND OF THE INVENTION 
       [0003]    Offshore oil and natural gas platform systems rely upon above sea platforms that support drilling and/or processing equipment to extract resources from subsea wells. The above sea platforms are mounted through a system of supports that extend from the offshore platform to the sea floor. Often times the supports are adjustable to account for changing sea and/or weather conditions. The supports position the above platform above a surface of the sea and include drilling systems, transport systems, support systems, such as electrical power generation, and crew accommodation systems. In addition to above sea platforms, many offshore platform systems include subsea platforms that support various systems at or near the sea floor. 
         [0004]    Subsea platforms include subsea systems that support the above sea platforms with extraction, storage, and transport of resources such as oil and natural gas. Sub-systems are transported to a particular site, submerged, integrated to form one or more subsea systems, and tested. Current technology limits that transport and positioning of each sub-system to about 500 metric tons (MT). Therefore, the installation of a subsea platform may be a lengthy process depending upon the size, weight, and number of sub-systems. More specifically, a subsea system may require multiple support ships to transport and position each sub-system as well as a lengthy construction and testing phase prior to being ready to support the above sea platform. 
       SUMMARY OF THE INVENTION 
       [0005]    In one embodiment of the present invention, a subsea platform transporter includes a plurality of pontoon members, a plurality of column members interconnecting select adjacent ones of the plurality of pontoon members forming a support frame having an inner platform receiving area, one or more buoyancy members mechanically linked to at least one of the plurality of pontoon members and the plurality of column members, and one or more platform retaining members mounted to one or more of the plurality of pontoon members and the plurality of column members about the inner platform receiving area. The one or more platform retaining members is configured and disposed to selectively retain and release a subsea platform supported by the subsea platform transporter. 
         [0006]    In another embodiment of the present invention, a subsea platform transporter system includes a subsea platform transporter having a plurality of pontoon members, a plurality of column members interconnecting select adjacent ones of the plurality of pontoon members forming a support frame having an inner platform receiving area, one or more buoyancy members mechanically linked to at least one of the plurality of pontoon members and the plurality of column members, and one or more platform retaining members mounted to one or more of the plurality of pontoon members and the plurality of column members about the inner platform receiving area. The subsea platform transporter system also includes a subsea platform including a fully integrated subsea system mounted within the inner platform receiving area through the plurality of platform retaining members. 
         [0007]    In accordance with yet another embodiment of the present invention, a method of transporting and submerging a fully integrated and tested subsea system includes assembling a plurality of sub-systems on a platform to form a fully integrated subsea system on shore, testing the fully integrated subsea system on shore, towing the fully integrated subsea system across a body of water to a location above the sea floor, and depositing the fully integrated subsea system on the sea floor. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]    The invention, together with further advantages thereof, may best be understood by reference to the following description taken in conjunction with the accompanying figures by way of example and not by way of limitation, in which: 
           [0009]      FIG. 1  depicts a perspective view of a subsea platform transporter system including a subsea platform transporter supporting a platform, in accordance with an exemplary embodiment; 
           [0010]      FIG. 2  depicts the subsea platform transporter system of  FIG. 1  being towed across a body of water; 
           [0011]      FIG. 3  depicts the subsea platform transporter system submerging toward a desired location on the sea floor; and 
           [0012]      FIG. 4  depicts ascent of the subsea platform transporter following release of the platform. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0013]    Reference will now be made in detail to embodiments of the invention, one or more examples of which are illustrated in the accompanying drawings. Each example is provided by way of explanation of the invention, not as a limitation of the invention. It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope of the invention. For instance, features illustrated or described as part of one embodiment can be used on another embodiment to yield a still further embodiment. Thus, it is intended that the present invention cover such modifications and variations that come within the scope of the appended claims and their equivalents. 
         [0014]    A subsea platform transport system (SPTS), in accordance with an exemplary embodiment, is indicated generally at  2 , in  FIG. 1 . SPTS  2  includes a subsea platform transporter (SPT)  4  including a first pontoon member  8 , a second pontoon member  9 , a third pontoon member  10 , and a fourth pontoon member  11 . Each pontoon member  8 - 11  includes one or more internal void spaces (not shown) filled with a ballast material (also not shown). The ballast material may take on a variety of forms including water, or high density materials such as various metals and alloys of metal. SPT  4  also includes a first column member  20 , a second column member  21 , a third column member  22 , and a fourth column member  23 . Of course it should be understood that the number of column members may vary. Column members  20 - 23  interconnect end portions (not separately labeled) of adjacent ones of pontoon members  8 - 11  to form an inner platform receiving area  27 . Each column member  20 - 23  includes one or more internal cavities  30  that are filled with a buoyant material  32 . Buoyant material  32  may take the form of hollow glass microspheres ( 34 ), thermosets, thermoplastics, light oils, foam concrete, low-density concrete or other materials that are buoyant in sea water. In this manner, column members  20 - 23  provide primary buoyancy for SPT  4 , as will be discussed more fully below. 
         [0015]    SPT  4  also includes a first plurality of buoyancy members  40  extending between first and second column members  20  and  21 , a second plurality of buoyancy members  41  extending between second and third column members  21  and  22 , a third plurality of buoyancy members  42  extending between third and fourth column members  22  and  23 , and a fourth plurality of buoyancy members  43  extending between fourth and first column members  23  and  20 . Each of the plurality of buoyancy members  40 - 43  includes one or more valves (not shown) that selectively control the ingress of sea water to adjust buoyancy of SPT  4 . SPT  4  is further shown to include a plurality of platform retaining members, three of which are indicated at  50 ,  51  and  52  and which may take the form of hydraulic latches that extend about a periphery of inner platform receiving area  27 . Platform retaining members may take on other forms including electrical latches, pneumatic latches and the like. Also, it should be understood that the particular arrangement and connection of buoyancy members  40 ,  41 ,  42 , and  43  may vary. 
         [0016]    In further accordance with the exemplary embodiment shown, SPT  4  includes a plurality of thrusters  60 - 67 . Two of the plurality of thrusters  60 - 67  is mounted to respective ones of column members  20 - 23 . Thrusters  60 - 67  are selectively activated to maneuver SPT  4  into a desired position, as will be detailed more fully below. SPT  4  further may include a first drag appendage  70  mounted to first pontoon member  8 , a second drag appendage  71  mounted to second pontoon member  9 , a third drag appendage  72  mounted to third pontoon member  10  and a fourth drag appendage  73  mounted to fourth pontoon member  11 . Each drag appendage  70 - 73  includes an open upper end, such as shown at  78 , with respect to first drag appendage  70 . Drag appendages  70 - 73  may be stationary or selectively deployable to control ascent of SPT  4  from the sea floor to the sea surface. A controller  84  provides a support vessel based operator with functionality to control buoyancy members  40 - 43 , platform retaining members  50 - 52 , column members  20 - 23 , and/or drag appendages  70 - 73 . Controller  84  is coupled to SPT  4  through an umbilical cable  86 . 
         [0017]    In still further accordance with an exemplary embodiment, SPT  4  supports and delivers a subsea platform  100  to a desired location on the sea floor. Subsea platform  100  supports a plurality of undersea sub-systems  104  that are connected to form a fully integrated subsea system  108 . The term “fully integrated” should be understood to mean that the system is in an operable condition needing only final connections to undersea components. The system is constructed and may be fully tested on shore, delivered to a desired location, and submerged as a functional system as will be detailed more fully below. 
         [0018]    After fully integrated subsea system  108  is assembled, and subsea platform  100  secured to SPT  4 , subsea platform transporter system (SPTS)  2  is towed out to sea, as shown in  FIG. 2 . One or more support ships (not separately labeled) transport SPTS  2  to a desired position above the sea floor. Once in position, SPTS  2  submerges toward a support structure  140  having a plurality of support members  142 - 145 . More specifically, buoyancy members  40 - 43  are selectively controlled to achieve a gradual descent of SPTS  2 . Buoyancy members  40 - 43  are gradually filled with sea water to facilitate descent of SPTS  2 . The rate of change of weight is controlled to account for changes in water density as depth increases. Once SPTS  2  nears support members  142 - 145 , thrusters  60 - 67  are selectively activated to achieve a desired alignment between pins (not shown) extending from subsea platform  100  and support members  142 - 145 . Once alignment is achieved, subsea platform  100  comes to rest upon support members  142 - 145 . 
         [0019]    After resting upon support members  142 - 145 , platform retaining members  50 - 52  are released, or hydraulically unlatched, by a signal passing from controller  84 . Once released, SPT  4  begins to ascend toward the sea surface, as shown in  FIG. 4 . Ascent of SPT  4  is controlled through drag appendages  70 - 73 . More specifically, drag appendages  70 - 73  ensure that SPT  4  ascends at a desired rate. In accordance with one aspect of the exemplary embodiment, drag appendages  70 - 73  may be deployed at varying angles to control ascent. Once at the sea surface, the one or more support ships will tow SPT  4  back to dock. At this point it should be understood that SPTS  2  is capable of delivering a fully assembled subsea system to a location on the sea floor. SPTS  2  may deliver loads of up to 3,000 metric tons dry weight or more to depths of up to 10,000 feet of water or more. By using a weight controlled descent through selective control of buoyancy members and a drag controlled ascent through the use of drag appendages and/or additional flooding of buoyancy members prior to the release of the subsea platform, the SPTS may reduce overall costs, time, and assembly of undersea installations. 
         [0020]    While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention. Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.