Abstract:
A apparatus is disclosed for attaching and sealing to the upper end of the casing allowing the inner string to be run through the apparatus. The apparatus provides a latch for anchoring the inner string and a seal for sealing on the inner string. Also disclosed is a flow path for providing for circulation of fluid between the inner string and casing annulus. Also disclosed is an inner string sub that provides a profile anchoring and sealing the inner string by the apparatus.

Description:
PRIORITY INFORMATION 
     This application claims the benefit of U.S. Provisional Application No. 60/366,115 on Mar. 20, 2002. 
    
    
     FIELD OF THE INVENTION 
     The field of this invention relates to a method of anchoring, sealing and circulating between a casing string and inner string therein. 
     BACKGROUND OF THE INVENTION 
     With the use of casing strings in wells, having small clearances between each string, it has become more common to run the casing string open ended to allow the fluid below the casing to escape through the inside of the casing to prevent an increase in pressure in the well that could break down the formation and cause a well control problem. 
     In order to run a casing string of this type into a sub sea well head it is necessary to run the casing inside the riser then attach a casing hanger and running tool to the casing and run the assembly in the well to the sub, sea tree using drill pipe. Normally the casing can then be cemented in place using conventional cementing plugs located at the hanger running tool and launched by dropping a ball or other device from the rig floor. In some instances it is desirable to run pipe below the hanger running tool to or near the bottom of the casing being run. This will eliminate the need for cementing plugs since there is no need to wipe the casing with cementing wiper plugs. 
     Should the well begin to flow the blow out preventer can be closed on the casing string isolating the annulus between the casing string being run and the well bore. The drill pipe being run inside the casing can also be isolated by connecting it to a top drive or by attaching a safety valve to the upper most joint of drill pipe. However this leaves the casing drill pipe (inner string) annulus open thereby exposing the well to extreme danger. 
     It is therefore clear there is a need for a device to isolate the annulus between the inner string and the casing string during the process of running the inner string inside the casing string. 
     Not only is it desirable to isolate this annulus space by placing a seal between the two members, it is also necessary to anchor the inner string to the casing string to prevent internal pressure in the casing string from pushing the inner string out of the well. 
     It is therefore clear there is a need for a device to anchor the inner string to the casing to prevent it from dropping into the well or being blown out of the well. 
     Should a gas bubble exist it must be circulated out of the well to place the well back under control. In order to circulate the well it is common practice to pump mud into the most inner string, in this case the drill pipe or inner string and out the annulus around the drill pipe. 
     It is therefore clear there is a need for a device to provide a means of circulating fluid through the well. 
     A device is disclosed that can be attached to the upper end of the casing string or casing hanger that will anchor the inner string to the casing to prevent it from moving. A seal is also disclosed that will seal the annulus between the inner string and casing at the surface, the device also provides for circulating fluid through the annulus space between the casing string and inner string. 
     Accordingly, it is an object of the present invention to provide a apparatus useful for anchoring, sealing and providing a circulation path in a casing string having an inner string. Accordingly, an apparatus is disclosed that provides for attaching and sealing to the upper end of the casing string or hanger and provides for the inner string to be run through the apparatus. A means of anchoring the inner string to the apparatus is also provided. Accordingly, an apparatus that provides a flow path for circulating fluid is disclosed. These and other objectives accomplished by the apparatus will become more apparent from a review of the detailed description below. 
     SUMMARY OF THE INVENTION 
     A apparatus is disclosed for attaching and sealing to the upper end of the casing allowing the inner string to be run through the apparatus. The apparatus provides a latch for anchoring the inner string and a seal for sealing on the inner string. Also disclosed is a flow path for providing for circulation of fluid between the inner string and casing annulus. Also disclosed is an inner string sub that provides a profile anchoring and sealing the inner string by the apparatus. 
     For running the inner string the apparatus provides an opening that does not restrict the passage of the tool joints of the inner string. Once it is decided to anchor or seal on the inner string the inner string sub is attached to the upper most joint of the inner string. This inner string sub is then lowered into the apparatus until the latching profile and seal area of the inner string sub is adjacent the latch and seal in the apparatus. The latch is then set by hydraulic pressure. The latch is tested by pulling or pushing (raising or lowering) the inner string. The seal can then be set by hydraulic pressure. Circulating fluid either into the casing inner string annulus or the inner string can test the seal. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an elevational view of the apparatus. 
     FIG. 2 is a sectional elevational view of the apparatus attached to the upper end of the casing string. 
     FIG. 3 is the view of FIG. 2, except that the inner string is being run through the apparatus. 
     FIG. 4 is a sectional elevational view of the apparatus in FIG. 2, except that the inner string sub has been attached to the inner string and positioned in the apparatus with the latching device and seal activated to anchor and seal the inner string with the apparatus. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIG. 1, an outer view of apparatus A is shown to illustrate the general location of components. Illustrated is a thread or latch  1  to engage the threads of the upper casing joint or profile of a hanger not shown in this illustration. The location of a seal  2  for sealing with the casing is illustrated. Also shown is the circulation port  3  whose purpose will be described later. Hydraulic ports  4 ,  5 ,  6  and  7  are illustrated. These ports are connected through hydraulic lines  4 ′,  5 ′,  6 ′ and  7 ′ to the latch and seal not shown in this illustration. Referring to FIG. 2, the apparatus A is shown connected to the upper end of the casing B by threads or latch  1  and sealed with the casing with seal  2 . The casing B is supported at the rig floor with slips or spider not shown. The circulating port  3  is connected to the inside of the casing B through passage  8  and annular area  9  between the casing B and apparatus A. For simplicity only hydraulic port  4  and hydraulic line  4 ′ are shown. Hydraulic port  4  is connected to the lower end of the seal setting piston  10  through port  11 . Ports  5 ,  6  and  7  of FIG. 1 are connected through their respective passages to ports  12 ,  13  and  14 . Ports  12 ,  13  and  14  are shown out of position to simplify the illustration. Each port will be rotationally displaced as are passages  5 ,  6  and  7  of FIG.  1 . So, hydraulic passage  5  of FIG. 1 is connected to the upper end of the seal setting piston  10  through port  12 , hydraulic passage  6  of FIG. 1 is connected to the lower end of the latch piston  15  through port  13 , and hydraulic passage  7  of FIG. 1 is connected to the upper end of the latch piston  15  through port  14 . 
     Seals  21 ,  22 , and  23  isolate ports  11 ,  12 ,  13  and  14  from each other inside of lower housing  16 . 
     Upper housing  16  of the apparatus is connected to lower housing  17  with threads  18 . Latch Housing  19  is attached to upper housing  16  with threads  20 . 
     Seal  24  is shown in its normally released position. It is clear that the seal  24  can be set by pressuring through hydraulic port  4  of FIG. 1 to the lower end of the seal setting sleeve  10 . Seal  24  is maintained in the released position by application of hydraulic pressure being applied through port  6  then passing through internal passageways to port  12  located at the upper end of seal setting piston  10  and acting on the annular area between seals  31  and  32 . 
     The latch  25  is shown in its normal released position with the inner profile of the latch piston  15  in the mating contact with the outer profile of the latch  25  so that the latch  25  is in its expanded (normally relaxed) position. Latch  25  is preferably a single piece design providing for expansion and contraction and formed from a tubular having slots  26  and  27  alternately formed from opposite ends and terminating prior to exiting the part. Latch piston  15  is held in the latch  25  release position with hydraulic pressure applied in the area between seal  28  and  29  through ports  7  and  14 . As pressure is applied to port  7  it advances through the internal paths to port  14  thereby forcing latch piston  15  downward into contact with latch  25  at shoulder  30 . Latch  25  in turn is forced into contact with latch housing  19  at shoulder  33 . 
     Referring to FIG.  3 . The apparatus A is shown connected to the casing B with the inner string C being run through the apparatus. In this view inner string C consists of adjacent joints of pipe  34  and  35 . Shown in the view are the spaces  36  and  37  created when the seal  24  and latch  25  are in the released position. In this position adjacent joints of pipe may be continuously added or removed from the inner string C without damage to the seal  24  or latch  25 . To prevent the upset  38  of the inner string C from damaging the latch  25  or seal  24  the inner diameter  40  of the lower housing  17  and the inner diameter  39  of the upper housing  16  are both smaller than the inner diameters of the latch  25  and seal  24  when in the released or retracted positions. 
     Referring to FIG.  4 . The apparatus is shown with the inner string sub  42  attached to the uppermost joint of pipe  41  in the inner string C. Another joint of pipe  43  is connected to the upper end of the inner string sub  42 . The upper joint of pipe  43  can be connected to the rig hoisting system so as to manipulate the inner string by raising or lowering it. 
     The inner string sub  42  has formed on its outside surface a set of profiles  48 ,  49  and  50  for engagement with mating profiles  51 ,  52  and  53  respectfully. Profile  51  of the latch  25  is preferably longer than any of the profiles on the inner string sub  42  other than the lowermost profile  48 . These longer profiles  48  and  51  prevent the latch  25  from contracting until all profiles are located to their respective mates. For this reason, once the inner string sub  42  is inserted into the apparatus such that the seal diameter  46  is through the latch  25 , hydraulic pressure can then be applied through port  7  of the apparatus through the inner passages and to port  13 , seals  29  and  54 . Pressure applied to this area will force latch piston  15  upward. This upward force on latch piston  15  will cause surface  55  of the latch piston to ride up surface  56  of the latch  36  forcing latch  36  inward into contact with the outer surface of seal area  46  on the inner string sub  42 . As the inner string C is then lowered the profiles on the inner string sub  42  will be placed adjacent to the profiles of the latch  25 . With pressure being applied to the area on the latch piston  15  the latch  26  will be forced into mating contact with the profiles of the inner string sub  42 . This will lock the inner string C in place so that it can not move upward or downward thereby assuring the seal surface  46  is always adjacent to the seal  42 . 
     Should pressure not be applied to the Latch piston  15  to position the profiles adjacent to each other, lowering the inner string C will eventually cause shoulder  44  on the inner string sub  42  to come into contact with the upper surface  45  of the upper housing  16  causing the inner string C to stop in a position that the profiles on the inner string sub  42  will be placed adjacent to the profile in the latch  36 . This will also place the seal surface of the inner string sub  42  adjacent the seal  24 . 
     Once in this position the latch  36  and seal  24  can be placed in locking and sealing contact with the inner string mandrel  42  by applying pressure to their respective ports. 
     Although a seal  24  is shown which takes an axial force to actuate other types of seals can be used such as those that have a chevron shape that will seal without actuation. Although a hydraulic means is described to actuate the latch  36  other types of actuation such as mechanically moving the latch piston  1  are envisioned. 
     Once the inner string sub  42  is secured by the latch  36 , pressure in the annular area between the casing B and inner string C can be controlled. Circulation into or out of this annulus is possible through port  3  as described earlier. 
     The system is released by bleeding the pressure from the latch and seal ports causing them to retract away from the inner string sub  42 .