Subsea well workover system and method

Abstract

A string of pipe is stored in a body of water for working over a subsea well. The string is stored in a substantially linear configuration having controlled curvatures along its length with radii that are not smaller than the minimum yielding radius of curvature of the pipe material. The string may be made up from individual segments of threaded pipe. One end of the string is inserted into the well using a pipe drive assembly connected with the wellhead. The opposite end of the string is connected to a line that extends to a surface facility. The string may be rested on the bottom of the sea or may be floated on the water surface or may be suspended with buoyancy devices in various orientations between the sea bottom and the water surface. The pipe string may be stored within a tubular sleeve or may be disposed directly in the seawater. When the pipe is substantially horizontally oriented, an arching guide is used to divert the working end of the string from its storage position to a substantially vertical position for insertion into the well. The drive and guide may be permanently associated with the well or may be portable for movement to another subsea well. The drive and guide may be mounted in a buoyancy-controlled assembly. A remotely operated vehicle (ROV) is used to assemble and move the guide, drive and pipe through the water.

1 . A method of extending a pipe string to a subsea well, comprising: 
 orienting the central axis of an axially extending unyielded section of pipe in a direction such that the central pipe axis is not parallel to the central axis of a subsea well;    moving the unyielded pipe section around a curving path such that the central pipe axis becomes parallel with the central axis of the subsea well, such curving path having a radius of curvature that is greater than the minimum allowable non-yielding bending radius of the pipe section whereby said pipe section is not yielded as a result of moving over said curving path;    inserting one end of said pipe string into said subsea well; and    propelling at least a portion of said pipe string through said subsea well with a propulsion mechanism submerged in a body of water that overlies said subsea well.    
     
     
         2 . A method as defined in  claim 1 , further comprising: 
 communicating power and/or fluid and/or data between said subsea well and a surface facility at a surface of said body of water.    
     
     
         3 . A method as defined in  claim 1 , further comprising: 
 servicing, working over or otherwise acting upon said subsea well with said pipe string.    
     
     
         4 . A method as defined in  claim 1 , further comprising: 
 securing said propulsion mechanism to said subsea well.    
     
     
         5 . A method as defined in  claim 1 , further comprising: 
 securing said propulsion mechanism to said subsea well with a remotely operated underwater vehicle.    
     
     
         6 . A method as defined in  claim 1 , further comprising: 
 moving the unyielded pipe section around a curving path of at least 90 degrees.    
     
     
         7 . A method as defined in  claim 1 , further comprising moving the unyielded pipe section around more than one curving path of at least 90 degrees.  
     
     
         8 . A method as defined in  claim 1 , further comprising controlling the position of said pipe string in said body of water with the use of buoyancy devices.  
     
     
         9 . A method as defined in  claim 1 , further comprising providing a curved guide for bending said pipe section around said curving path.  
     
     
         10 . A method as defined in  claim 9 , further comprising supporting said curved guide on a flotation device.  
     
     
         11 . A method as defined in  claim 1 , further comprising placing said pipe string in a sleeve for isolating at least a part of said pipe string from the water in said body of water.  
     
     
         12 . A method of working on a subsea well, comprising: 
 placing a linearly extending length of a metal pipe within and/or on a water body overlying said subsea well in a substantially non-vertical orientation,    forming a bend in a portion of said linearly extending length of metal pipe within said body of water, below a surface of said body of water, without yielding said metal pipe in said bend, whereby a portion of said metal pipe is oriented substantially parallel to a central axis of a well pipe already installed in said subsea well,    inserting said substantially parallel oriented length of metal pipe directly from said body of water adjacent said subsea well into said well pipe of said subsea well, and    working on or in said well with the assistance of said extended length of metal pipe.    
     
     
         13 . A method as defined in  claim 12 , further comprising: 
 communicating power and/or fluid and/or data between said subsea well and a surface facility at said surface of said body of water.    
     
     
         14 . A method as defined in  claim 12 , further comprising: servicing, working over or otherwise acting upon said subsea well with said pipe string.  
     
     
         15 . A method as defined in  claim 12 , further comprising: 
 inserting said substantially parallel oriented length of pipe into said well pipe with a propulsion mechanism.    
     
     
         16 . A method as defined in  claim 15 , further comprising: 
 securing said propulsion mechanism to said subsea well with a remotely operated underwater vehicle.    
     
     
         17 . A method as defined in  claim 12 , further comprising: 
 forming said bend around a curving path of at least 90 degrees.    
     
     
         18 . A method as defined in  claim 12 , further comprising forming bends around more than one curving path of at least 90 with sections of linearly extending pipe positioned between said bends.  
     
     
         19 . A method as defined in  claim 12  and bad, further comprising controlling the position of said pipe string in said body of water with the use of buoyancy devices.  
     
     
         20 . A method as defined in  claim 12 , further comprising providing a curved guide for bending said pipe section around said curving path.  
     
     
         21 . A method as defined in  claim 20 , further comprising supporting said curved guide on a flotation device.  
     
     
         22 . A method as defined in  claim 12 , further comprising placing said pipe string in a sleeve for isolating at least a part of said pipe string from the water in said body of water.  
     
     
         23 . A method of working on a subsea well with an elongate string of pipe, comprising: 
 placing an axially extending, elongate string of pipe in or above a body of water overlying the subsea well, non-yieldingly bending a portion of the string of pipe from an orientation that is substantially non-parallel with the axis of the well to an orientation that is substantially parallel with the axis of the well, and extending the substantially parallel portion of the string of pipe into direct contact with the water body and through the water body directly into the subsea well.    
     
     
         24 . A method as defined in  claim 23  further comprising securing together multiple lengths of tubular pipe sections to form said elongate string of pipe.  
     
     
         25 . A method as defined in  claim 24  wherein said multiple lengths of tubular pipe sections have a flush joint connection whereby said elongate string of pipe has a substantially constant outside diameter along a major portion of its assembled length.  
     
     
         26 . A method as defined in  claim 23  wherein at least a portion of said elongate string of pipe is supported in or above said water body with buoyancy devices.  
     
     
         27 . A method as defined in  claim 23  wherein a submerged powered drive mechanism connected with the subsea well propels the parallel portion of the elongate string of pipe into the well.  
     
     
         28 . A method as defined in  claim 27  wherein said powered drive mechanism is movable from one subsurface well location to another subsurface well location.  
     
     
         29 . A method as defined in  claim 23  wherein a surface support facility connects through said elongate string of pipe to the subsea well.  
     
     
         30 . A method as defined in  claim 23  wherein said elongate pipe string is bent at a location below the surface of the water body.  
     
     
         31 . A method as defined in  claim 23  wherein said elongate pipe string is bent at a location above the surface of the water body.  
     
     
         32 . A method as defined in  claim 24  wherein said elongate pipe string is bent at a location adjacent the subsea well.  
     
     
         33 . A method as defined in  claim 23  wherein said elongate pipe string is bent through a change of direction of at least  90  degrees at multiple locations along its length and whereby each such bend is a non-yielding bend of the pipe string.  
     
     
         34 . A system for working on an underwater well, comprising: 
 a surface support facility at the surface of a body of water overlying said underwater well,    a pipe string connected between said surface support facility and said underwater well,    said pipe string having a linearly extending first length that is substantially non-vertically disposed and a second linearly extending length that is substantially vertically disposed, said first length positioned intermediate said second length and said surface support facility, and    a powered drive mechanism positioned between said first section and said underwater well for inserting said second length into said underwater well.    
     
     
         35 . A system as defined in  claim 34 , comprising: 
 at least one bend in said pipe string between said first and second linearly extending lengths whereby the orientation of said linearly extending string changes from said substantially non-vertically disposed position to said substantially vertically disposed position, such bend having a radius of curvature that does not exceed the bending radius of curvature of the material of the pipe string that would cause yielding of the material of the pipe string.    
     
     
         36 . A system as defined in  claim 35  wherein said bend occurs within the body of water.  
     
     
         37 . A system as defined in  claim 35  wherein said bend occurs above the body of water.  
     
     
         38 . A system as defined in  claim 34  wherein said powered drive mechanism is secured to said underwater well.  
     
     
         39 . A system as defined in  claim 34  wherein said surface support facility provides fluids and/or power and/or communication between said surface support facility and said underwater well.  
     
     
         40 . A system as defined in  claim 34  wherein controlled buoyancy devices are used to regulate the position of said pipe string within said body of water.  
     
     
         41 . A system as defined in  claim 34  wherein said pipe string and said powered drive mechanism and said underwater well are equipped with connecting structures for engagement with and/or manipulation by a remotely operated underwater vehicle.  
     
     
         42 . A system as defined in  claim 34  having a protective sleeve that prevents contact with at least a portion of said pipe string with the water within said body of water.  
     
     
         43 . A system defined in  claim 34  wherein said first length of said pipe string is substantially horizontally disposed in or above said body of water.  
     
     
         44 . A system as defined in  claim 34  wherein said pipe string has at least two bends along its length, such bends separated from each other by lengths of linearly extending pipe and providing a change in direction of at least 90 degrees and having a radius of curvature less than the minimum, non-yielding bending radius of the material of the pipe.  
     
     
         45 . A system as defined in  claim 34  wherein the least a portion of said pipe string rests on the bottom of said body of water.