Abstract:
The disclosure concerns a method and apparatus for repairing or structurally reinforcing an oil and gas well tubular member, or an assembly of tubular members. The assembly to be repaired can include a smaller diameter inner flow conveying conduit (or production tubing) and a larger diameter concentrically placed surface casing, providing an annulus in between the production tubing and the surface casing. A third casing pipe of largest diameter, the drive pipe is placed around the surface casing string. Other “conductor” casing pipes can be positioned around the surface casing inside the drive pipe. Part of the surface casing string (or other conductor pipe) can suffer damage due to corrosion. A sleeve or repair member is placed around the casing string or other tubular member at a damaged portion.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   Not applicable 
   STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
   Not applicable 
   REFERENCE TO A “MICROFICHE APPENDIX” 
   Not applicable 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a new method and apparatus that does not mandate the use of a drilling rig for repairing and structurally reinforcing tubular members that are next to a casing head assembly on an oil or gas well, and in one embodiment, casing string (or other conductors) contained inside of an outer drive pipe. 
   2. General Background of the Invention 
   In the oil and gas well drilling and production industry, casing arrangements are typically used as part of a well. These casing arrangements often include a smaller diameter inside production casing contained concentrically within the bore of a larger diameter surface casing string. There may be additional casing strings referred to as conductors. The outer most casing is referred to as a drive pipe. The production tube, surface casing, and conductors if present, are concentrically placed inside of an outermost drive pipe or like tubular member. A casing head assembly is provided at the top of the surface casing or conductor string. A grout filler often occupies the annulus that is in between the outer drive pipe and the inner casing strings to an elevation, if in a marine environment, somewhere in between the mud line and casing head assembly. 
   Such an assembly of drive pipe, casing strings, typically extend between the casing head assembly, which is what the wellhead or blow out preventor attaches to, and the oil or gas reservoir. 
   Moisture can accumulate from condensation, rain, etc. in between the outer drive pipe and inner casing string at the uppermost elevation. This creates a corrosion cell that can structurally weaken or perforate the conductor or surface casing. Often there are multiple conductors (in addition to the surface casing string) that are in between the outer drive pipe and the innermost production tubing. If there is only one conduit in between the outer drive pipe and the inner production tubing, it is typically referred to as the surface casing. Additional conduits in this area between outer drive pipe and surface casing are referred to as conductors. Historically, mobilization of a drilling rig has been required whenever repairs to one of the gas or oil well casing strings is needed. 
   Patents have issued that relate generally to the concept of a method and apparatus for protective encapsulation of structural members. 
   One early patent is the Papworth U.S. Pat. No. 4,068,483 entitled “Protective Sheath for Water-Eroded Wood Piling”. In the Papworth patent, the sheath is for a water-eroded wood piling. The sheath is a longitudinally split, flexible and resilient plastic casing with overlapping circumferentially end segments. The casing has a preformed, integral spout at its upper end into which wet concrete can be poured to fill the casing around the eroded section of the piling. Flexible bands clamp the casing tightly around the piling, and the spout has aligned openings in its opposite sides for passing the uppermost one of these bands. The casing may comprise two or more longitudinal sections in overlapped sealed engagement with each other end-to-end for enclosing a long eroded section of the piling. 
   In the Colbert U.S. Pat. No. 4,023,374, there is disclosed a repair sleeve for a marine pile and a method of applying same. The &#39;374 patent discloses a preformed molded fiberglass resin plastic repair sleeve for use on a marine or other submerged concrete pile and a method of applying the same. The sleeve is provided with at least one vertical seam consisting of inside interlocking reentrant bends which together establish an interlocking tongue and groove joint. The joint is maintained effective by self-tapping screws which are in engaged relation with steel closure clips or strips. The sleeve after assembly is centered about the pile undergoing repair and the continuous space which exists between the sleeve and the pile is filled with a suitable grout which, when hardened, encompasses the internal or inside portions of the joint under pressure and prevents unfastening of the seam. The vertical longitudinal extend of the sleeve is somewhat greater than the water depth of the partially submerged pile to which it is applied and, where a cylindrical concrete pile is concerned, the sleeve is molded on an arcuate bias so as to present an open gap enabling the sleeve to be readily slipped sidewise onto the pile by one or more divers and the gap thereafter closed in order to effect the interlocked joint. Where a square pile is undergoing repair, the sleeve assumes a conformable four-sided shape or, alternatively, it may be formed of two mating right-angle sleeve sections having a pair of vertical inside interlocking joints or seams between their adjoining side margins. 
   The Straub U.S. Pat. No. 4,114,388 discloses a device for protecting a pile from ice formations collecting on it and subsequently abstracting the pile as a result of a variation of tide level including a tapered guard member secured to the pile. The guard member is firmly secured to the pile by interconnecting stiffening members, horizontal stiffening rings, vertical fin members and compression rings which also serve to prevent deformation of the guard member taper as a result of interaction with the ice formations. The guard member comprises two sections connected by vertically extending tongue and groove joints. 
   The Moore U.S. Pat. No. 4,306,821 discloses a system for the restoring and reconditioning of structural piling. The system provides an outer form which is attachable to a portion of the piling which has been eroded or corroded and has lost some of is thickness and thus its overall strength. A diameter building filler is placed into the intraform space between the form and the piling, the filler providing a protective and structural coating to that portion of the piling where corrosion or damage has taken place. In the preferred embodiment, the filler is a setting material such as a suitable epoxy. 
   Three patents have issued to Richard Snow and Milton Ellisor. These patents include U.S. Pat. Nos. 4,876,896; 4,892,410; and 4,993,876. The &#39;896 and &#39;410 patents discloses a method and apparatus for forming an encapsulation or encasement about a structural member that is said to be suited for use in a marine environment. A two-component polymer system for protective and repair encapsulation is pumpable in two separate strings to the location of the structural member to be encapsulated. The two reactive components are combined in a static mixer immediately prior to be injected within the surrounding translucent jacket. By combining the reactive components immediately prior to use, premature setup is avoided and the resulting grout may be directed to flow upwardly in the jacket for enhancing final properties. By suitable coloring of the components, visual monitoring of the final mixing and distribution in the translucent form or jacket of the encapsulation material may be monitored. A field test for determining bond strength of the encapsulation polymer to the structural member is also disclosed in the &#39;876 patent and in the &#39;410 patent. The &#39;896 patent discloses a method of testing protective encapsulation of structural members. 
   The above discussed patents all relate primarily to coatings for protecting against corrosive effects of the surrounding marine environment. However, the prior art fails to address a problem of structural reinforcement for structural members that have become weak because of the corrosive and/or mechanical effects of the surrounding environment. Further, these patented prior art systems do not address concentric, pipe within pipe configurations. 
   Other patents that discuss repair methods are the Fox U.S. Pat. No. 4,091,301 and the Moran U.S. Pat. No. 967,952, both references cited in U.S. Pat. No. 6,536,991 naming applicants herein as inventors. U.S. Pat. No. 6,536,991 is incorporated herein by reference. 
   BRIEF SUMMARY OF THE INVENTION 
   The present invention provides a method of repairing an oil or gas well having a platform that has an outer drive pipe, an inner production flow line, and one or more intermediate conductors or surface casing strings that are concentrically positioned in between the inner production flow line and the outer drive pipe. 
   The repair method of the present invention identifies a corroded or other damaged portion of the intermediate conductor or conductors or casings. As part of the method of the present invention, a section of the drive pipe is removed to provide an upper cut edge. 
   A sleeve or other repair member (e.g. half sleeve, quarter sleeve, curved plate) is installed that spans between upper and lower positions that are above and below the damaged section of the surface casing string (or conductor). The sleeve that is installed over the damaged section can have a longitudinal slot or slots that enable it to be open for installation on the casing string. The sleeve can be metallic or non-metallic (e.g., composite). 
   If the sleeve is metallic, it can be welded to the selected casing or conductor with preferably upper and lower girth welds. The sleeve slots are then closed with longitudinally extending welds or connections. If the sleeve is of a precured composite material, it can be secured about the damaged section using an adhesive. Additionally, the composite repair may be formed in place where the reinforcement material and resin are combined on site. In this case, the resin that makes the composite rigid is also the adhesive. 
   The sleeve can be comprised of two sleeve sections, each having a transverse semicircular shape. When two metallic sleeve sections are used, there are two slots and each of the slots is closed with a longitudinal weld or connection. 
   In one embodiment, there are two sleeves, an inner sleeve that is connected to or welded to the surface casing or conductor and an outer sleeve that is connected to or welded to the outer drive pipe. 
   A grout product (e.g., epoxy, polymeric, or cement grout) can be added to the annulus between outer drive pipe and inner conductor or casing string. Multiple embodiments of the method of the present invention are disclosed. In keeping with the method of the present invention, a repair could include any figure shown and described herein of  FIGS. 1–15  or a combination of multiple of the drawing  FIGS. 1–15 , and corresponding descriptions. This repair method of the present invention restores structural integrity as well as pressure containment/load capacity for the casing or conductor that is repaired and thus to the casing string assembly below the casing head assembly. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     For a further understanding of the nature, objects, and advantages of the present invention, reference should be had to the following detailed description, read in conjunction with the following drawings, wherein like reference numerals denote like elements and wherein: 
       FIG. 1  is a partial sectional elevation view of the preferred embodiment of the method and apparatus of the present invention, illustrating a method step of the preferred method of the present invention; 
       FIG. 2  is an elevation view of the preferred embodiment of the method and apparatus of the present invention, illustrating a method step of the present invention; 
       FIG. 3  is a partial perspective view of the preferred embodiment of the method and apparatus of the present invention and illustrating the inner sleeve portion; 
       FIG. 4  is a partial sectional elevation view of the preferred embodiment of the method and apparatus of the present invention, illustrating a method step of the present invention; 
       FIG. 5  is a partial sectional elevation view showing a second embodiment of the method and apparatus of the present invention, illustrating an alternate method step of the present invention; 
       FIG. 6  is a partial sectional elevation view showing a second embodiment of the method and apparatus of the present invention, illustrating a method step of the present invention; 
       FIG. 7  is a partial perspective view of a third embodiment of the method and apparatus of the present invention; 
       FIG. 8  is a partial sectional elevation view of the third embodiment of the method and apparatus of the present invention, illustrating a method step of the present invention; 
       FIG. 9  is a partial sectional elevation view of the third embodiment of the method and apparatus of the present invention, illustrating a method step of the present invention; 
       FIG. 10  is a partial sectional elevation view of the third embodiment of the method and apparatus of the present invention, illustrating a method step of the third embodiment of the present invention; 
       FIG. 11  is a partial sectional elevation view of the fourth embodiment of the method and apparatus of the present invention; 
       FIG. 12  is a sectional elevation view of a fifth embodiment of the method and apparatus of the present invention, illustrating a method step of the fifth embodiment; 
       FIG. 13  is a partial sectional elevation view of the sixth embodiment of the method and apparatus of the present invention, illustrating a method step of the sixth embodiment; 
       FIG. 14  is a partial sectional elevation view of the sixth embodiment of the method and apparatus of the present invention, illustrating a method step of the sixth embodiment; and 
       FIG. 15  is a partial sectional elevation view of the sixth embodiment of the method and apparatus of the present invention, illustrating a method step of the sixth embodiment; 
   

   DETAILED DESCRIPTION OF THE INVENTION 
     FIGS. 1–4  show the preferred method and apparatus of the present invention. A second embodiment of the method and apparatus of the present invention is shown in  FIGS. 5 and 6 . A third embodiment of the method and apparatus of the present invention is shown in  FIGS. 7–10 . 
   A fourth embodiment of the method and apparatus of the present invention is shown in  FIG. 11 . A fifth embodiment of the method and apparatus of the present invention is shown in  FIG. 12 . 
     FIGS. 13–15  show a sixth embodiment of the method and apparatus of the present invention. 
   In  FIG. 1 , a wellhead area  1  is shown that has a casing head assembly  2  of a gas or oil well. Connected to the casing head assembly  2  is a casing string  3 . Flanges at the top of the casing head assembly  1  can accept either a blow out preventor (BOP) for drilling operations, or a wellhead/“christmas tree” for production. Inside the casing string  3  there is provided a casing string bore  5  that contains a production tubing or production flow line  6  having a production tubing bore  7 . There can be a diameter transition section  4  between casing head assembly  2  and casing string  3  created by the weld securing the casing head  2  to the surface casing  3  or conductor. 
   Surrounding casing string  3  is an outer drive pipe  8 . An annulus  9  is provided in between outer drive pipe  8  and casing string  3 . The bore  5  of casing string  3  defines an annulus in between the production tubing or flow line  6  and surface casing string  3 . This assembly of tube shaped members  3 ,  6 ,  8  can include additional cylindrically shaped conductors that are positioned in between the outer drive pipe  8  and casing string  3 . 
   This assembly shown in  FIG. 1  can also include a grout  10  that typically is positioned in annulus  9 . Grout  10  can also be placed in the annulus  5  that is in between casing string  3  and inner production tubing  7 . 
   Outer drive pipe  8  has an upper end  11  and an open top  12  that could have a trash cover in place. If grout  10  becomes damaged, or was never installed to an uppermost elevation next to casing head assembly  2 , water can collect in the annulus  9  just below casing head assembly  2 . It should be understood that in general, such a wellhead area  1  having casing head assembly  2 , casing string  3 , production tubing  7  and outer drive pipe  8  is an assembly that is well known in the art. 
   Because of the accumulation of or exposure to water in part of the annulus  9  that could be filled with grout  10 , corrosion can produce a damaged portion  13  to casing string  3  (or to other conductor pipes) over a period of time. For example, this damaged portion  13  can be in the form of rust or corrosion on the outer surface  14  of the casing string  3 . 
   As part of the method, in  FIG. 2  a cut  16  is made at the level of reference line  15  and below damaged portion  13 . Any grout above reference line  15  is removed. The removed section  17  is shown on phantom lines in  FIG. 2 . A cut  16  is produced when a section  17  is removed. 
   In  FIG. 3  there is a provided a sleeve  18  having half sections  19 ,  20  and inner surfaces  21 ,  22  respectively. This sleeve  18  is attached to the damaged section  13  of casing string  3  after it has been cleaned, sandblasted and/or water blasted to remove as much of the rust and corrosion as is possible. 
   Upper girth weld  23  and lower girth weld  24  are used to attach the sleeve  18  to casing string  3  at the position shown in  FIG. 4 . The upper girth weld  23  is above damaged portion  13 . The lower girth weld  24  is below damaged portion  13 . 
   Longitudinal welds  25  are used to connect the edges  26 ,  28  of half section  20  to edges  27 ,  29  of half section  22 . This combination of girth welds  23 ,  24  and longitudinal welds  25  secures the sleeve  18  to the surface  14  of casing string  3 . 
   Grout  10 , if present below edge  16  is removed to provide a cavity  30  that communicates with the lower end portion of sleeve  18  as shown in  FIG. 4 . The grout is removed sufficiently to provide access for making the lower weld  24  and to place new grout if desired. The upper cut edge  16  should be at a level that enables weld  24  to be made. 
   In  FIG. 7 , a second sleeve  31  is shown that can be installed as shown in  FIGS. 8 ,  9  and  10  by connecting the sleeve  31  to the upper end portion of outer drive pipe  8  at cut  16 . The second sleeve  31  can be formed of two half sections  32 ,  33 . 
   Each half section  32 ,  33  is preferably provided with a pair of longitudinally extending flanges. The first half section  32  has longitudinally extending, opposed flanges  34 ,  35 . The second half section  33  has longitudinally extending flanges  46 ,  47 . Each half section  32 ,  33  includes a curved portion. The half section  32  has curved portion  36 . The half section  33  has curved portion  42 . 
   A lower most flange  37  is an arc shaped flange fastened to the bottom of half section  32 . Each of the longitudinally extending flanges  34 ,  35  is provided with a plurality of openings  50  that can receive bolted fasteners  51 . Likewise, the longitudinally extending flanges  46 ,  47  of half section  33  provide openings  55  that can receive bolted fasteners  51 . 
   The lower end portion of half section  33  has a curved or arc shaped flange  43 . Each of the curved or arc shaped flanges  37 ,  43  can have inner and outer parts such as the inner part  44  and the outer part  45  shown in  FIG. 7  for the flange  43 . Each of the arc shaped flanges  37 ,  43  has a lower surface  53  that can be welded at  52  for joining the lower flange  37  or  43  to the upper edge or cut  16  part of the outer drive pipe  8 . 
   A plurality of injection ports  39 ,  40 ,  41  are provided on sleeve  31  half sections  32 ,  33 . The sleeve half section  32  has injection ports  39 ,  40 . The sleeve half section  33  has an injection port  41 . 
   In  FIG. 8 , the second sleeve  31  is shown attached to outer drive pipe  8  at upper cut edge  16  using girth weld  52 . A grout product  57  (for example, epoxy, polymeric, or cement grout) can be pumped into the space in between the second sleeve  31  and the combination of first sleeve  18  and casing string  3 , the completed repair being shown in  FIG. 10 . 
   In the embodiment of  FIGS. 7–10 , axial load and moment transfer is accomplished with the sleeves  18 ,  31  and grout product  57 . 
   In  FIGS. 5 and 6 , a sleeve  54  is similar to the sleeve  31  of  FIGS. 7–10 . Sleeve  54  can be made of two half sections and then welded together in the position of  FIGS. 5–6 . However, the sleeve  54  is welded at circumferential weld  56  to upper cut  16  edge of the outer drive pipe  8  as shown in  FIGS. 5 and 6 . The space in between the sleeve  54  that is welded at  56  to upper drive pipe  8  can be filled using flow line  58  pumping a grout product into the space  59  such as a polymer, epoxy, or cement grout. This method of  FIGS. 5 and 6  can also be used to restore a cut away section of an inner conductor or surface casing. 
   In  FIG. 11 , a composite sleeve  60  is placed around the damaged section  13  of surface casing or conductor  3 . Grout product  57  can be placed as a watershed or for corrosion protection in between the sleeve  60  and the outer pipe  8  up to the top of outer drive pipe  8  at the cut edge  16 . 
   In  FIG. 12 , a jacket  62  (e.g. composite) can be added as a second sleeve to restore the drive pipe  8 . The jacket  62  is spaced from the outer drive pipe  8  using spacer  63 . The composite jacket  62  is spaced from the first sleeve  60  using spacers  61 . A lower seal  64  is placed in between the bottom of jacket  62  and outer drive pipe  8  as shown in  FIG. 12 . One or more injection ports  65  can be provided for pumping a grout product  57  into the space that is in between the second sleeve or outer jacket  62  and first sleeve  60  and existing drive pipe  8 . 
   In  FIGS. 13 ,  14  and  15 , a sleeve  60  is placed over the damaged portion  13  of the casing string  3 . A mold  66  is then placed against the outer surface of outer drive pipe  8  as shown in  FIG. 13 . A concrete cylinder  70  is then formed that encircles both casing string  3  and repair sleeve  60  as shown in  FIG. 13 . In  FIG. 14 , the mold  66  is removed by separating mold halves  67 ,  68  as indicated by the arrows  69 . The concrete cylinder  70  can then be covered with a cylindrically shaped composite sleeve  71  as shown in  FIG. 15 . The sleeve  71  can be formed (field applied) in place using a combination of reinforcing material and resin, for example. 
   PARTS LIST 
   The following is a list of suitable parts and corresponding parts descriptions for the various parts used in this specification. 
   PART NO. DESCRIPTION
           1  wellhead area     2  casing head assembly     3  surface casing or conductor     4  transition (connection weld)     5  casing string bore     6  production tubing/casing     7  production tubing bore     8  outer drive pipe     9  annulus     10  grout     11  upper end     12  open top     13  damaged portion     14  outer surface     15  reference line     16  cut     17  removed section     18  sleeve or curved repair member     19  half section     20  half section     21  inner surface     22  inner surface     23  upper girth weld     24  lower girth weld     25  longitudinal weld     26  edge     27  edge     28  edge     29  edge     30  cavity     31  sleeve     32  half section     33  half section     34  flange     35  flange     36  curved portion     37  flange     38  opening     39  injection port     40  injection port     41  injection portion     42  curved portion     43  flange     44  inner pant     46  flange     47  flange     48  curved part     50  opening     51  bolted fastener     52  girth weld     53  lower surface     54  sleeve/sleeve half section     55  opening     56  weld     57  grout     58  flow line     59  space     60  composite sleeve     61  spacer     62  composite jacket     63  spacer     64  lower seal     65  injection port     66  mold     67  mold half     68  mold half     69  arrow     70  concrete cylinder     71  composite sleeve       

   The foregoing embodiments are presented by way of example only; the scope of the present invention is to be limited only the following claims.