Abstract:
A subsea well containment and intervention apparatus. The invention provides a rigid frame that includes a set of pilings for securely affixing the apparatus to the seafloor. Buoyancy modules included in the frame make the weight of the invention more manageable when in the water. Lifting eyes are provided on the frame for installation and removal. A series of tools are attached to the frame to eliminate the need for frequent trips to the surface to replace and replenish.

Description:
PRIORITY CLAIM 
       [0001]    This application claims priority from Provisional Application Ser. No. 61/351,361 filed Jun. 4, 2010. 
     
    
     FIELD AND BACKGROUND OF INVENTION 
       [0002]    The invention is generally related to subsea well bores and more particularly to a subsea well containment and intervention apparatus. 
         [0003]    Containment of a leak and intervention of an offshore subsea well poses significant risks. 
         [0004]    The main tool for intervention is an ROV (remotely operated vehicle) and this tool may be well suited for observation and carrying out small tasks. However, heavy tools requiring high loads are required for any subsea well intervention. 
         [0005]    One has to keep in mind the significant pressures encountered in an oil well. Pressures of 10,000+ psi are common place. Managing a simple task may become impossible due to the high pressures encountered. 
         [0006]    In addition, the integrity of the well and its attachments are usually in question when intervention is required. The well components must be handled delicately for fear that further damage can be caused. 
         [0007]    ROV&#39;s do not have the necessary power needed to handle large size tools and strength required to manage the intricate maneuvers. Limited capability of the ROV&#39;s puts a serious restriction on the range of operations possible. 
         [0008]    ROV&#39;s are limited in their endurance and flexibility. They will have to return to the surface for maintenance, and replenishment of tools or consumables. Return to the surface is a slow process. When time is of the essence in any leak containment or intervention operation, the functionality of the ROV is questioned. 
       SUMMARY OF INVENTION 
       [0009]    The present invention addresses the problems in the known art. The invention provides a rigid frame that includes a set of pilings for securely affixing the apparatus to the seafloor. Buoyancy modules included in the frame make the weight of the invention more manageable when in the water. Lifting eyes are provided on the frame for installation and removal. A series of tools are attached to the frame to eliminate the need for frequent trips to the surface to replace and replenish. 
         [0010]    The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming part of this disclosure. For a better understanding of the present invention, and the operating advantages attained by its use, reference is made to the accompanying drawings and descriptive matter, forming a part of this disclosure, in which a preferred embodiment of the invention is illustrated. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    In the accompanying drawings, forming a part of this specification, and in which reference numerals shown in the drawings designate like or corresponding parts throughout the same: 
           [0012]      FIG. 1  is a general isometric view of the basic components of the invention. 
           [0013]      FIG. 2  illustrates the steel beams and tools used with the invention. 
           [0014]      FIG. 3  illustrates the positioning of the invention over a well head. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0015]    The subsea well containment and intervention apparatus  10  is generally comprised of a frame  12 , buoyancy modules  14 , piles  16 , a series of tools, and means for controlling the tools. 
         [0016]    As seen in  FIG. 1 , the frame  12  is preferably formed from a plurality of steel beams  18  attached together. It is preferred they form essentially a cross or X shape. The steel beams  18  are preferably sized to handle a minimum of 10,000 tons of force both upwards and downwards. The size and length of the steel beams  18  are selected to suit the most common offshore sites. 
         [0017]    The beams  18  are attached together so as to define an open central well  20  which can be placed over the well head  22 . The open central well  20  allows the use of tools stowed on the apparatus  10  for working on the subsea well. 
         [0018]    A plurality of lifting eyes  24  are rigidly attached to the frame  12  to provide attachment points for lifting and lowering the apparatus  10  to the seafloor. 
         [0019]    A plurality of pilings  16 , also referred to as piles (one or more at each end of the frame  12 ) are provided and are rigidly attached to the steel beams  18 . Piles  16  are preferably suction piles. At least one evacuation pump  26  is provided on each pile  16 , which is closed at the upper end. The diameter and length of the piles  16  are selected to suit the most common offshore sites and soil conditions. The piles  16  are used to establish the apparatus  10  in place around the well head  22 . 
         [0020]    As known in the offshore industry, suction piles are open at the lower end and closed at the upper end and eliminate the need for a pile driving device by placing the lower open end of the pile on the seafloor and using an evacuation pump to remove air and water from the interior of the pile. The negative pressure created inside the pile causes the pile to be pushed into the soil by the external water pressure on the pile which is greater than the internal pressure. 
         [0021]    It is preferable that the evacuation pumps  26  be of the positive displacement type and it is estimated that they should be able to create at least 2,500 psi differential pressure or more using either electrical or hydraulic power. 
         [0022]    The evacuation pumps  26  are connected to a pump control center  28  that is preferably located on one of the steel beams  18 . An umbilical connector  30  mounted on the same steel beam as the pump control center  28  is used to bring aboard a control, electrical, and hydraulic umbilical line  32 . 
         [0023]    Buoyancy modules  14  serve to reduce the effective submerged weight of the apparatus  10  and make handling from the surface more manageable. While any suitable type of buoyancy module may be used, syntactic foam buoyancy modules are preferred. 
         [0024]    As indicated above, a series of tools may be provided on the apparatus  10 .  FIG. 2  illustrates some examples of possible tools that can be used such as a wellhead cleaning tool  34 , a flow control tool  36 , a pressure plug ram  38 , or a pipe connector  40 . The tools are normally kept in their stowed position and deployed as required for use once the apparatus  10  is installed on the seafloor  42 . Using the top and bottom of the frame  12 , as many as eight tools can be installed on the apparatus  10 , thus minimizing or eliminating the need for repeated trips to the surface. Jacks  44  can be used for positioning the tools. Umbilical line  32  extends from a surface support vessel and is connected to umbilical connector  30  that serves as means for providing electrical and hydraulic power to and controlling the tools. Power and control lines not shown are provided on the frame  12  as needed for the tools. 
         [0025]    A wellhead cleaning tool  34  can be used to prepare a damaged well head for being capped or being connected to a flow control tool  36  such as that illustrated in  FIG. 2 . Jack  44  is used to move the flow control tool  36  into fluid communication with the well head  22  such that the oil and/or natural gas from the well flows through a flow diverter riser  46  into pipe connector  40  and into a pipe or riser not shown for safely diverting oil and/or natural gas from a damaged well. 
         [0026]      FIGS. 2 and 3  illustrate a pressure plug ram  38  mounted on a skid plate  48  via extension jacks  50 . The skid plate  48  is movably mounted on the frame  12  and moved between positions by a jack  44 . As seen in  FIG. 3 , the pressure plug ram  38  has been moved from a first retracted position to a second deployed position where it is aligned with the central well  20  and the well head  22 . The extension jacks  50  are used to force the pressure plug ram  38  into the well head  22  to block the flow of oil and/or natural gas from the well into the surrounding environment. 
         [0027]    While only the pressure plug ram  38  is shown as being mounted on a skid plate  48  for movement during work on a well head, it should be understood that skid plates may be used for all of the tools to provide the greatest versatility for movement and working capability. 
         [0028]    The control, electrical, and hydraulic umbilical line  32  provides a continuous supply of power to the tools. 
         [0029]    The flow control tool  36  is connected to the flow diverter riser  46  that takes the flow away from the well head and through a riser to the surface. 
         [0030]    One special tool is the pressure plug ram  38 . As the steel beams  18  are designed for 10,000 tons force, the pressure plug ram  38  is placed on either side and can exert the maximum force on top of the well head  22  to plug the well totally independent of the well and wellhead components  52 . As shown in  FIG. 3 , the pressure plug ram  38  is brought directly over the well head  22  and using the extension jacks  50  the leaking well is sealed. 
         [0031]    In operation, the apparatus  10  is lowered by a surface vessel using lifting eyes  24  and positioned above a subsea well head  22 . Once the piles  16  contact the seafloor  42  the evacuation pumps  26  are activated to drain water and air from the piles  16 . The pressure differential between the inside and outside of the piles causes the piles to be driven into the seafloor  42  and fix the apparatus  10  in place. Tools such as the well head cleaning tool  34 , the flow control tool  36 , or the pressure plug ram  38  are then used as needed to properly capture and direct the flow of oil and/or natural gas or to plug the well. When the work is completed and there is no longer a need for the apparatus  10  at the site, the evacuation pumps  26  can be used to pump water into the piles and create a pressure differential that pushes the piles out of the seafloor  42  and allow apparatus  10  to be lifted to the surface and recovered for reuse at another location. 
         [0032]    The invention provides several advantages. 
         [0033]    It provides a strong, rigid and stable platform in and around the subsea wellhead. 
         [0034]    It provides a platform where a multitude of tools can be placed onboard prior to deployment and can be used independently. 
         [0035]    It provides means of exerting a significant amount of force independent of the well and well head components. 
         [0036]    It provides a steady stream of power to the tools. 
         [0037]    The apparatus is removable and reusable. 
         [0038]    While specific embodiments and/or details of the invention have been shown and described above to illustrate the application of the principles of the invention, it is understood that this invention may be embodied as more fully described in the claims, or as otherwise known by those skilled in the art (including any and all equivalents), without departing from such principles.