Abstract:
A non-rotational casing hanger and seal assembly running tool for use in oil and gas drilling operations has a mandrel and a tool body that is carried by the mandrel. The tool body supports a plurality of latching segments for releasably connecting the tool body to a seal assembly. A plurality of latching dogs on the tool body releasably connect the tool body to a casing hanger. Axial movement between the tool body and mandrel operates a pressure responsive shuttle piston positioned on the mandrel to urge the seal assembly into sealing position. A ball valve positioned in the mandrel bore is operable between open and closed positions to allow independent operations to be carried out such as cementing the casing hanger in position through the mandrel bore and operating the shuttle piston to then allow overpull to unlatch the tool from the casing hanger for retrieval.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to an installation tool for landing a casing hanger in a wellhead and setting a seal assembly in the annulus between the casing hanger and wellhead in a single trip. The installation tool can perform these functions without requiring any rotation of the drill pipe string used for lowering the installation tool, casing hanger and seal assembly into the bore of a subsea wellhead. 
     The non-rotational casing hanger and seal assembly running tool of the present invention is used in oil and gas drilling operations of the type typically referred to as subsea. These type of oil and gas operations have a wellhead sitting on the ocean floor. As drilling operations proceed, various sizes of casing hangers will be lowered into the wellhead, each casing hanger having a length of casing threaded into to the lower end of the casing hanger. The lengths of casing typically will be from a few hundred feet in length for the larger size casings to several thousand feet of casing for the smaller sizes of casing. The casing hanger itself is a generally tubular member with a beveled outer shoulder sized to land on a mating inner shoulder in the wellhead or a previously installed casing hanger. 
     After each casing hanger and attached string of casing is landed in the wellhead a cement slurry is pumped through the casing hanger and casing. This cement slurry is forced to the bottom of the casing string where it then flows around the bottom end of the casing string and back up the annulus between the casing string and the drilled hole. After the cement has been placed, a seal assembly or packoff is lowered into the wellhead where it is urged into the annulus between the casing hanger and the inner wall or bore of the wellhead. The seal assembly often requires some mechanism to urge it into its sealed or energized position to ensure a positive seal in the annulus between the casing hanger and the inner wall or bore of the wellhead. 
     The seal assemblies used in this type of oil and gas drilling operations are typically either an elastomeric seal using the natural elasticity of a rubber compound to seal the annulus or a metal seal using a soft metal compound formed into a plurality of lips that are deformed or energized into contact with the bore of the wellhead and outside diameter of the casing hanger to form the aforementioned annular seal. The metal seals require substantially more force to deform and energize them into their sealing configuration. Previous designs in the industry have either used torque or annulus pressure to energize these metal seals. Those designs utilizing torque have used rotation of the drill string to operate a threaded ring to apply the needed force. These designs have a couple of major limitations: it is difficult to determine how much of the applied torque is being applied to the threaded ring and how much of the torque is being expended in rotation of the long drill pipe string and the drag of the drill pipe string on the wellbore and as wellheads are deployed in ever greater water depths more of the applied torque is lost in the drag of the drill pipe string on the wellbore than is applied to the threaded ring. The previous designs using annulus pressure have been limited by the pressure that can be applied in the annulus between the inner and outer casing strings being sealed. This pressure limitation prevents enough pressure from being generated to generate the substantial force required to energize a metal seal. 
     Additionally, it is preferable if the tool used to lower the casing hanger and set the seal assembly in the casing hanger—wellhead annulus can accomplish these tasks in one trip. As wells are drilled in ever deeper water depths, the time for lowering a tool to the sea floor and retrieving it increases dramatically and this translates into higher drilling costs as the cost of the rig time required to perform these operations is high. It is therefore desirable to have an installation tool that can lower a casing hanger and associated seal assembly into a well bore, land the casing hanger, allow cementing and energize the seal assembly in a single trip without requiring rotation of the drill string. The non-rotational casing hanger and seal assembly running tool of the present invention offers a substantial improvement by offering a tool that can perform these functions in a single trip and allow testing of the installed seal assembly without requiring rotation of the drill striing. 
     2. Description of Related Art 
     U.S. Pat. No. 4,903,776 to P. C. Nobileau et al. shows a casing hanger running tool using drill string tension to set the packoff. The axial movement of the drill string is used in conjunction with differential area pistons to apply force on a sleeve to set the packoff. 
     A casing hanger running tool using string weight is disclosed in U. S. Pat. No. 4,928,769 to L. J. Milberger et al. This device also uses the weight of the drill string acting on differential area pistons to drive a setting sleeve downward to set the packoff. 
     SUMMARY OF THE INVENTION 
     The non-rotational casing hanger and seal assembly running tool of the present invention is designed for use in those subsea applications where non-rotation of the drill string is preferred or a requirement, i.e., primarily deep water applications or those involving reeled pipe installations. The non-rotational casing hanger and seal assembly running tool includes a mandrel having an upper end adapted for connection to a string of drill pipe and a bore therethrough. A tool body is carried by the mandrel and the mandrel and the tool body are axially moveable relative to one another. 
     The tool body includes a main body, an upper body and a lower body having a lower end adapted for connection to a string of drill pipe. The main body of the tool body supports a plurality of latching segments circumferentially spaced for releasably connecting the tool body to a seal assembly. A plurality of latching dogs are positioned circumferentially on the lower body of the tool body for releasably connecting the tool body to a casing hanger. The axial movement between the tool body and mandrel operates a pressure responsive shuttle piston positioned on the upper body to urge the seal assembly into the annulus between the casing hanger and a wellhead in which the casing hanger is landed. 
     The mandrel also includes a ball valve positioned in the mandrel bore that is operable between open and closed positions by axial movement of the mandrel relative to the tool body. The opening and closing of the ball valve allows independent operations to be carried out such as cementing the casing hanger in position through the mandrel bore and operating the shuttle piston to unlatch the tool from the casing hanger for retrieval. 
     A principal object of the present invention is to provide a seal assembly and casing hanger installation tool that can install a seal assembly and a casing hanger without requiring rotation of the drill pipe string used to lower the seal assembly and casing hanger to the subsea wellhead. 
     Another object of the present invention is to provide a seal assembly and casing hanger installation tool that can install a seal assembly and casing hanger in a single trip. 
     A final object of the present invention is to provide a seal assembly and casing hanger installation tool that can perform the additional functions of cementing the casing hanger and perform pressure testing of the seal assembly after installation in a single trip. 
     These with other objects and advantages of the present invention are pointed out with specificness in the claims annexed hereto and form a part of this disclosure. A full and complete understanding of the invention may be had by reference to the accompanying drawings and description of the preferred embodiments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other objects and advantages of the present invention are set forth below and further made clear by reference to the drawings, wherein: 
         FIGS. 1A ,  1 B and  1 C comprise a full sectional view of the installation tool for landing a casing hanger in a wellhead and setting a seal assembly in the annulus between the casing hanger and wellhead without requiring rotation of the drill pipe string of the present invention with a seal assembly secured on the installation tool and the installation tool lowered into a casing hanger. 
         FIGS. 2A ,  2 B and  2 C comprise a half sectional view of the installation tool secured to the casing hanger by the latching dogs. 
         FIGS. 3A ,  3 B and  3 C comprise a half sectional view of the installation tool during well bore cementing operations. 
         FIGS. 4A ,  4 B and  4 C comprise a half sectional view of the installation tool as the seal assembly is urged into the annulus between the casing hanger and a wellhead housing. 
         FIGS. 5A ,  5 B and  5 C comprise a half sectional view of the installation tool as the seal assembly is tested. 
         FIGS. 6A ,  6 B and  6 C comprise a half sectional view of the installation tool as disengaged from the casing hanger, prior to retrieval to the surface. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     With reference to the drawings, and particularly to  FIGS. 1A ,  1 B and  1 C a full sectional view of installation tool  10  for landing a casing hanger in a wellhead and setting a seal assembly in the annulus between the casing hanger and wellhead without requiring rotation of the drill pipe string of the present invention is shown. Installation tool  10  includes mandrel  12  with central bore  14  extending therethrough and tool body  16  carried on mandrel  12  and axially moveable relative to mandrel  12 . Mandrel connector  18  is secured to the upper end of mandrel  12  by suitable connection means as threads  20 . Mandrel connector  18  has internal drill pipe thread  22  formed at the opposite end for connection to a drill pipe string (not shown) that is used for lowering installation tool  10  to a wellhead positioned on the seafloor. Mandrel connector  18  is sealed to mandrel  12  by lip seals  24  adjacent threads  20 . 
     The lower end of mandrel  12  has selectively operable closure means or ball valve  26  secured thereon by threads  28  and sealed by lip seals  30 . Ball valve  26  has flow control member or ball  32  positioned in its central bore that is selectively operable by movement of ball pin  34 . Movement of ball pin  34  rotates ball  32  between open and closed positions thereby opening and closing bore  14  of mandrel  12 . Movement of ball pin  34  is controlled by the relative movement between mandrel  12  and tool body  16  in a manner to be described hereinafter. 
     Tool body  16  is composed of upper body  36 , main body  38  and lower body  40 . Upper body  36  is secured to the upper end of main body  38  by threads  42  and lower body  40  is secured to the upper end of main body  38  by threads  44 . Upper body  36  forms piston  46  at its upper end with exterior seals  48  sealing on the interior of shuttle piston  50 . Three sets of interior seals  52  are spaced axially along the interior of piston  46 . The position of interior seals  52  relative to lateral port  54  in mandrel  12  controls the flow of pressurized drilling fluid from lateral port  54  to piston port  56  and thereby the movement of shuttle piston  50 . The movement of mandrel  12  relative to upper body  36  opens and closes this passage. Lip seals  58  on the interior of annular shoulder  60  of shuttle piston  50  allow cycling of shuttle piston  50 . In the initial running position shown in  FIG. 1 , shuttle piston  50  is prevented from movement relative to upper body  36  by frangible connection means as tensile bolts  62 , circumferentially spaced around upper body  36  in counterbore holes  64 . Counterbore holes  64  are plugged with pipe plugs  66  to ensure the pressure integrity of piston  46 . 
     Shuttle piston  50  is a generally cylindrical member with stepped outer shoulder  68  adjacent to interior annular shoulder  60 . Lower skirt  70  extends axially downward from stepped outer shoulder  68 . A plurality of flow ports  72  are circumferentially spaced around lower skirt  70  and allow drilling fluid to flow between the interior and exterior of shuttle piston  50 . A plurality of laterally disposed and circumferentially spaced counterbore holes  74  are formed adjacent the lower end of lower skirt  70 . Frangible connection means as shear bolts  76  are positioned in holes  74  and threaded into mating holes in actuator rod head  78 . Actuator rod head  78  is an annularly shaped flange with a plurality of actuator rods  80  secured at its inner edge and circumferentially spaced. Actuator rods  80  extend axially from lower skirt  70 . 
     Main body  38  of tool body  16  is secured to upper body  36  by threads  42  as noted above. Main body  38  is a generally cylindrically shaped member surrounding mandrel  12 . Actuator rod holes  82  are formed at the upper end of main body  38  and aligned with actuator rods  80  when installation tool  10  is assembled. Positioned on the exterior of main body  38  are a plurality of connection means as latching segments  84  that are axially moveable in tracks  86  formed on the exterior of main body  38 . Latching segments  84  are initially held in the up position of  FIG. 1  by frangible tensile bolts  88  extending through retainer flange  90 . Retainer flange  90  is fastened to main body  38  by bolts  92 , shown in  FIG. 2B , that are circumferentially spaced from tensile bolts  88 . In the up, i.e., initial running position of  FIG. 1 , latching segments  84  extend radially outward sufficiently to allow retainer lip  94  to engage the interior of seal assembly  96  and hold seal assembly  96  in place. 
     Seal assembly  96  is designed to effect a metal to metal seal in the annulus between the casing hanger and wellhead. Seal assembly  96  includes outer seal lips  98  and inner seal surfaces  100  that are urged into sealing engagement with the wellhead and casing hanger. Actuator ring  102  urges seal assembly  96  into its sealing position when acted upon by lower skirt  70  of shuttle piston  50 . Lock ring  104  engages a complementary groove in the wellhead to lock seal assembly  96  in place. 
     Lower body  40  of tool body  16  is secured to main body  38  by threads  44  as noted above. Lower body  40  is a generally cylindrically shaped member surrounding mandrel  12 . Apertures or windows  106  are formed at the upper end of lower body  40  and evenly spaced around the circumference of lower body  40 . Dogs  108  are disposed in windows  106  and include multiple shoulders  110  formed on their outer periphery. Dogs  108  are radially moveable and multiple shoulders  110  engage mating shoulders  112  in casing hanger  114  when installation tool  10  is landed in casing hanger  114 . Casing hanger  114  is of the mandrel or shouldered type, with frustoconical outer shoulder  116  designed to land on mating shoulder  118  of previous casing hanger  120  which is landed in wellhead  122  (See  FIG. 3B ). Frustoconical outer shoulder  116  has mud slots  124  formed in its outer periphery and evenly spaced circumferentially to allow drilling fluid to be circulated past casing hanger  114 . The lower end of lower body  40  has drill pipe thread  126  formed thereon for connection to cementing equipment, well known to those of ordinary skill in the art. 
     Radial movement of dogs  108  is controlled by cam ring  128  positioned on mandrel  12 . Cam ring  128  is initially retained by spring plunger  130 , radially disposed in lower body  40 . Cam ring  128  is aligned with actuator rods  80  through lower body  40  by alignment pin  132 . Retrieval ring  134  is positioned near the upper end of cam ring  128  to ensure cam ring  128  is held in position during retrieval of installation tool  10 . 
     The initial assembly of installation tool  10 , seal assembly  96  and casing hanger  114  is shown in  FIGS. 1 and 2 . Seal assembly  96  is secured to the exterior of main body  38  as noted above and installation tool  10  is set in casing hanger  114  with dogs  108  retracted ( FIG. 1 ). Weight is set on mandrel  12  that overrides the detenting of spring plunger  130  and moves axially allowing cam ring  128  to urge dogs  108  radially outwardly and engage mating shoulders  112  in casing hanger  114  ( FIG. 2 ). Shuttle piston  50  is in its upward position and ball valve  32  is open. At this point, installation tool  10 , seal assembly  96  and casing hanger  114  are lowered into wellhead  122 . 
     As best seen in  FIG. 3 , installation tool  10 , seal assembly  96  and casing hanger  114  are landed in wellhead  122  with frustoconical outer shoulder  116  of casing hanger  114  setting on mating shoulder  118  of previous casing hanger  120 . Although shown with casing hanger  114  sitting on previous casing hanger  120 , it will be understood by those of ordinary skill in the art that casing hanger  114  could be landed on a mating shoulder (not shown) in wellhead  122 , if appropriately sized, without departing from the scope of the present invention. Ball  32  is open and normal cementing operations are carried out to cement casing (not shown) suspended from casing hanger  114  through central bore  14  of mandrel  12 . 
     Referring to  FIG. 4 , with cementing operations completed, weight is set on mandrel  12  to allow mandrel  12  to move axially relative to tool body  16 . This causes ball pin  34  to close ball  32 . Pressure is then applied through the drill string to bore  14  of mandrel  12 . The axial movement of mandrel  12  causes lateral port  54  to align with piston port  56 . Pressure applied in bore  14  acts through ports  54  and  56  and on top of annular shoulder  60  between exterior seals  48  and lip seals  58 . This force breaks tensile bolts  62  and shuttle piston  50  can move axially. This axial movement of shuttle piston  50  allows lower skirt  70  to act on seal assembly  96  and actuator ring  102  and urge seal assembly  96  into its sealing position. Actuator ring  102  also moves lock ring  104  into a mating groove in wellhead  122  and locks seal assembly  96  in position. As seal assembly  96  is moved into position, latching segments  84  release seal assembly  96 , and latching segments  84  move radially inwardly. Also, as shuttle piston  50  moves axially, shear bolts  76  are sheared and actuator rods  80  contacts cam ring  128  and retrieval ring  134  to lock them to mandrel  12 . 
     Referring to  FIG. 5 , pressure testing of seal assembly  96  is accomplished by applying pressure in the kill and choke lines (not shown) to apply pressure in the annulus between casing hanger  114  and wellhead  122  and on top of seal assembly  96 . This pressure also serves to cycle shuttle piston  50  back to its initial (up) position. This is due to the force acting on the lower side of annular shoulder  60  between seals  48  and  58 . Since shear bolts  76  are broken, actuator rod head  78  and actuator rods  80  are left in the lower position locking cam ring  128  and retrieval ring  134  to mandrel  12 . 
     As best seen in  FIG. 6 , once pressure testing is completed and it is desired to retrieve installation tool  10 , tension is applied to mandrel  12 . This tension on mandrel  12  and axial movement of mandrel  12  causes cam ring  128  and retrieval ring  134  to move with mandrel  12 , thereby releasing cam ring  128  from behind dogs  108 . Continued tension on mandrel  12 , causes shoulders  110  on dogs  108  to cam against shoulders  112  on casing hanger  114  and urge dogs  108  radially inwardly in windows  106 . Installation tool  10  can then be retrieved to the surface. 
     The construction of our seal assembly and casing hanger installation tool will be readily understood from the foregoing description and it will be seen that we have provided a seal assembly and casing hanger installation tool that can install a seal assembly and a casing hanger without requiring rotation of the drill pipe string used to lower the seal assembly and casing hanger to the subsea wellhead. Furthermore, while the invention has been shown and described with respect to certain preferred embodiments, it is obvious that equivalent alterations and modifications will occur to others skilled in the art upon the reading and understanding of the specification. The present invention includes all such equivalent alterations and modifications, and is limited only by the scope of the appended claims.