Patent Abstract:
A downhole tool cleans debris from a subsea well with nozzle assemblies that selectively deploy from the tool. The nozzle assemblies are in fluid communication with an annulus of a drill pipe on which the downhole tool is mounted, so that fluid pumped into the drill pipe discharges from nozzles provided with the nozzle assemblies. The nozzle assemblies are strategically situated so that when deployed, a stream discharged from nozzles on the assemblies clears debris from a surface between a casing hanger and wellhead housing. The nozzle assemblies are coupled to an annular piston coaxially set on the tool; and sliding the piston axially along the tool deploys the nozzle assemblies. Axially spaced apart ports extend radially through the tool to opposing faces on a head of the piston. Blocking one of the ports with a ball dropped down the drill pipe moves the piston and deploys the assemblies.

Full Description:
BACKGROUND 
       [0001]    1. Field of Invention 
         [0002]    The present disclosure relates in general to a device for use in completing a wellbore. More specifically, the present disclosure relates to a device for removing debris from a casing hanger prior to setting a seal between the casing hanger and wellhead housing. 
         [0003]    2. Description of Prior Art 
         [0004]    Subsea wells typically include a wellhead assembly with a wellhead housing that anchors on the subsea floor. Concentric strings of casing and tubing depend into the well and are supported by the wellhead housing. A tubular casing hanger is usually employed for mounting the casing string within the wellhead housing, where an upper end of the string threads onto the hanger. The casing hanger typically lands on a landing shoulder in the wellhead, or on a previously installed casing hanger having larger diameter casing. Cement is pumped down the string of casing to flow back up the annulus around the string of casing. 
         [0005]    Seals are typically installed between concentric wellhead tubular members to contain internal well pressure. One of the tubulars often includes a shoulder that radially projects towards the other tubular and defines a landing platform or support for a seal. Because the shoulder is usually exposed to well fluids during completion of the well, debris can collect or be deposited on the shoulder. The presence of debris on the shoulder can compromise seal integrity. 
       SUMMARY OF THE INVENTION 
       [0006]    Described herein is an example of a downhole tool for cleaning debris from a subsea well that includes a tool body having an axial bore, a nozzle assembly on the tool body having a discharge end in selective fluid communication with the bore in the tool body, a piston selectively movable axially along the tool body, and a deployment system. In this example the deployment system is made up of an elongated member that is coupled to the tool body by a pivoting connection. The elongated member also pivotingly connects to the piston and the nozzle assembly. When the piston axially slides along the tool body, the elongated member pivots about the tool body and repositions the nozzle assembly radially outward from the tool body. The downhole tool can further include an upper port in the tool body that extends radially outward from the axial bore and a lower port in the tool body that extends radially outward from the axial bore and that is spaced axially away from the upper port. In one example, the piston has a face in fluid communication with the upper port and an opposing face in selective fluid communication with the lower port, so that when fluid communication is blocked between the opposing face and lower port, the piston axially slides along the tool body. In this example, a radius of the axial bore decreases to define a shoulder adjacent the lower port that is strategically profiled to selectively receive a ball for blocking fluid communication between the axial bore and the lower port. The elongated member can be a first elongated member, and the deployment system further includes a second elongated member having end portions respectively pivotingly attached to the piston and the nozzle assembly and a middle portion pivotingly attached to a middle portion of the first elongated member. Optionally, the deployment system and nozzle assembly are strategically dimensioned so that when the tool body is inserted into a casing hanger coaxially disposed in a wellhead housing, a cleaning stream discharged from the nozzle assembly is directed into an annulus between the casing hanger and wellhead housing for cleaning debris from within the annulus. An outer groove may optionally be included along an axial portion the tool body that projects radially inward from an outer circumference of the tool body, and an inner groove may also be provided that projects radially inward from the outer groove. In this example the piston includes a tubular body that is axially slidable in the outer groove, and a ring like head projecting radially inward from the tubular body and axially slidable in the inner groove. 
         [0007]    Also disclosed herein is a downhole tool for use in forming a wellhead assembly subsea that is made from an annular tool body with an axial bore, an upper port extending radially through the tool body, and a lower port extending radially through the tool body, a piston mounted on the tool body having a face in fluid communication with the upper port and an opposing face in selective fluid communication with the lower port. Also included with this downhole tool is a nozzle assembly that has a flow line whose inlet is in fluid communication with the upper port and an exit, where the nozzle assembly is selectively movable from a running position stowed adjacent the tool body to a deployed position, so that the exit is directed to a designated area in the wellhead assembly. The downhole tool can further have a deployment means for deploying the nozzle assembly from the running position to the deployed position. In this example, the deployment means is an elongated member having am end portion pivotingly attached to the tool body, a distal end portion pivotingly attached to the nozzle assembly, and a middle portion coupled with the piston, so that when pressurized fluid is provided to the axial bore while fluid communication between the axial bore and lower port is blocked, pressurized fluid flows through the upper port to the face to axially move the piston thereby rotating the elongated member and urging the nozzle assembly into the deployed position. Further in this example, the elongated member is a first elongated member, and the deployment means further includes a second elongated member having end portions pivotingly connected respectively to the piston and the nozzle assembly and a middle portion pivotingly attached to a middle portion of the first elongated member. In one example, the lower port is axially displaced from the upper port and wherein the axial bore narrows adjacent the lower port to define a shoulder configured so that when a ball is set on the shoulder, the ball blocks fluid communication between the axial bore and the lower port. Optionally, the deployment system and nozzle assembly are strategically dimensioned so that when the tool body is inserted into a casing hanger coaxially disposed in a wellhead housing, a cleaning stream discharged from the nozzle assembly is directed into an annulus between the casing hanger and wellhead housing for cleaning debris from within the annulus. The downhole tool may optionally include an outer groove along an axial portion the tool body that projects radially inward from an outer circumference of the tool body, and an inner groove that projects radially inward from the outer groove and wherein the piston comprises a tubular body that is axially slidable in the outer groove, and a ring like head projecting radially inward from the tubular body and axially slidable in the inner groove. In this example, the head is disposed between the upper and lower ports when the nozzle assembly is in the running position, and is moved to adjacent the lower port when the nozzle assembly is in the deployed position. Connections are optionally included at upper and lower ends of the tool body for connection to a drill string. 
         [0008]    An example of a method of clearing debris from an annulus between a casing hanger and a wellhead housing is disclosed that includes providing a cleaning tool having a body, an axial bore, a nozzle assembly mounted on the tool body that is in fluid communication with the axial bore, and a deployment means for positioning the nozzle assembly into a cleaning position and coupling the cleaning tool within a tool string having an annulus that registers with the axial bore. The method also includes inserting the tool string into the casing hanger, pressurizing axial bore by flowing pressurized fluid into the annulus, deploying the nozzle assembly by selectively providing fluid communication between the axial bore and the deployment means so that a discharge end of the nozzle assembly is directed between the casing hanger and the wellhead housing, and cleaning an area between the casing hanger and wellhead housing by discharging pressurized fluid from the discharge end of the nozzle. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0009]    Some of the features and benefits of the present invention having been stated, others will become apparent as the description proceeds when taken in conjunction with the accompanying drawings, in which: 
           [0010]      FIG. 1  is a side sectional view of an example embodiment of a debris cleaner in accordance with the present invention. 
           [0011]      FIG. 2  is a side sectional view of the debris cleaner of  FIG. 1  being deployed adjacent a casing hanger in accordance with the present invention. 
       
    
    
       [0012]    While the invention will be described in connection with the preferred embodiments, it will be understood that it is not intended to limit the invention to that embodiment. On the contrary, it is intended to cover all alternatives, modifications, and equivalents, as may be included within the spirit and scope of the invention as defined by the appended claims. 
       DETAILED DESCRIPTION OF INVENTION 
       [0013]    The method and system of the present disclosure will now be described more fully hereinafter with reference to the accompanying drawings in which embodiments are shown. The method and system of the present disclosure may be in many different forms and should not be construed as limited to the illustrated embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey its scope to those skilled in the art. Like numbers refer to like elements throughout. 
         [0014]    It is to be further understood that the scope of the present disclosure is not limited to the exact details of construction, operation, exact materials, or embodiments shown and described, as modifications and equivalents will be apparent to one skilled in the art. In the drawings and specification, there have been disclosed illustrative embodiments and, although specific terms are employed, they are used in a generic and descriptive sense only and not for the purpose of limitation. 
         [0015]    Shown in a side sectional view in  FIG. 1  is an example of a tool string  10  that includes a debris cleaner  12  coaxially mounted in a string of drill pipe  14 . In the example of  FIG. 1 , the drill pipe  14  depends downward from a lower end of the debris cleaner  12  and inserts into a casing hanger  16  shown mounted on the sea floor  17 . Also mounted in the sea floor  17  is a wellhead housing  18  shown circumscribing the casing hanger  16 . A riser (not shown) may mount on the wellhead housing  18  and provide a conduit for inserting the tool string  10  within as the tool string  10  is lowered subsea. 
         [0016]    Debris cleaner  12  is shown including an annular lower body  20  whose lower portion is configured into a pin end  22  that threadingly connects to a box end  24  on an upper end of the drill pipe  14 . An upper body  26  coaxially mounts onto the lower body  20  on an end opposite the drill pipe  14 , and similarly includes a pin end  28  on its lower end that threadingly attaches to a box end  30  formed on an upper end of the lower body  20 . An axial bore  32  is shown extending through the drill pipe  14 , lower body  20 , and upper body  26 . 
         [0017]    Nozzle assemblies  34  are provided with the debris cleaner  12 , which are shown in a running position in  FIG. 1  disposed adjacent to the lower and upper bodies  20 ,  26 . In the example of  FIG. 1 , the nozzle assemblies  34  are elongate members having an end coupled on the debris cleaner  12 , and a distal portion provided with a nozzle  35  from which a cleaning fluid stream is discharged ( FIG. 2 ). A deployment means is provided for selectively deploying the nozzle assemblies  34  outward from the debris cleaner  12 . In an example the deployment means includes a scissor connection  36  that is made up of an elongated arm  38  having one end coupled to the lower body by a pinned connection  40 , so that the arm  38  can pivot about the connection  40  and rotate with respect to the lower body  20 . An end of arm  38  distal from pinned connection  40  is connected to the nozzle assembly  34  by pinned connection  42 , so that the arm  38  can pivot about the connection  42  and rotate with respect to the nozzle assembly  34 . In the example of  FIG. 1 , the pinned connection  42  mounts onto a housing  43  that covers a portion of the nozzle assembly  34 . Shown in a mid portion of the arm  38  is a pinned connection  44  that pivotingly connects the arm  38  to another arm  46 . Arm  46  has an end mounted onto the housing  43  by pinned connection  48 , so that arm  46  can rotate with respect to the nozzle assembly  34  and about pinned connection  48 . On an end of arm  46  distal from pinned connection  48  a pinned connection  50  that pivotingly mounts arm  46  to a piston  54  shown circumscribing a portion of the upper end lower bodies  26 ,  20 . As described in more detail below, the piston  54  is also part of the deployment means for deploying the nozzle assemblies  34 . 
         [0018]    An outer circumference of the piston  52  defines a generally tubular shaped body  54 , and the inner circumference of the piston  52  includes a head  56  that projects radially inward from the body  54 . In the example of  FIG. 1 , the head  54  is at about an axial mid portion of the body  54 , but embodiments exist where the head  54  could be axially offset from the mid portion. An outer groove  58  is illustrated that is formed along the circumference of the debris cleaner  12  and extending axially across the interface where the lower and upper bodies  20 ,  26  are joined. An inner groove  60  is shown in the upper body  26  that projects radially inward from a portion of the outer groove  58 . The inner groove  60  can be at about a mid portion of the outer groove  58 , or offset therefrom. In the example of  FIG. 1 , the outer groove  58  is dimensioned so that the piston body  54  may axially slide therein, and similarly the inner groove  60  is dimensioned to receive the piston head  56  therein and allow the piston head  56  to slide an axial distance therein. In the example of  FIG. 1 , the piston  52  is biased upward by a spring  62  so that the upper end of the piston body  54  contacts a lower facing end of the upper groove  58  and the upper end of the piston head  54  contacts a lower facing surface of inner groove  60 . 
         [0019]    Still referring to  FIG. 1 , an upper port  64  is shown projecting radially outward through the upper body  26  and from the bore  32  and to the inner groove  60 . Thus, upper port  64  provides fluid communication between bore  32  and upper face  65  that is defined by a lateral upward facing side of the piston head  54 . Further illustrated in  FIG. 1  is a lower port  66  that projects radially outward from the bore  32  into the inner groove  60  therefore providing fluid communication between the bore  32  and a lower face  67 , which is defined by a lower facing lateral surface of the piston head  54 . In the example of  FIG. 1 , ports  64 ,  66  are both open so that fluid pressure in the bore  32  is exerted substantially equally along upper face  65  and lower face  67  thereby equalizing pressure forces on piston  52 . The pressure equalization, in addition to the upwardly biasing force of spring  62 , retains the piston  52  in its illustrated position. Radius of the bore  32  projects radially inward in the region between ports  64 ,  66  and defines an upward facing shoulder  68 . The shoulder  68  is configured to receive a ball  70  thereon and as will be described in more detail below, provides a means for positioning the nozzle assemblies  34  into a deployed configuration. 
         [0020]    Referring now to  FIG. 2 , the debris cleaner  12  is shown in a deployed configuration for cleaning a space between the facing hanger  16  and wellhead housing  18 . As shown, the ball  70  is landed in shoulder  68  (or seat) so that by pressuring the portion of the bore  32  above the ball  70 , a pressure differential can be created across the piston head  56  due to differing pressures applied to the upper and lower faces  65 ,  67 . For example, the ball  70  blocks fluid communication from pressurized fluid in the bore  32  and into port  66 . However, pressurized fluid is allowed to enter into the inner groove  60  via port  64 , as increasing pressure in upper port  64  exceeds pressure in lower port  66 . The piston  52  is urged downward so that the lower end of the piston body  54  contacts a lower end of the outer groove  58 , and lower face  67  contacts an upper terminal end of the inner groove  60 . By downwardly moving piston  52 , arms  38 ,  46  are rotated about their respective pinned connections  40 ,  42 ,  44 ,  48  drawing pinned connections  40 ,  50  axially more proximate and projecting ends of the arms  38 ,  46  having pinned connections  42 ,  48  radially outward from the bodies  20 ,  26 . As the housing  43  mounts to the bodies  20 ,  26  on the ends of the arms  38 ,  46  having pinned connections  42 ,  48 , housing  43  is urged radially outward from the  20 ,  26 . 
         [0021]    As shown, the nozzle assemblies  34  include a flexible hose  72  having one end that inserts within an upper end of housing  43 , and another end coupled to an outer surface of the piston body  54 . Hose  72  is in fluid communication with fluid in the inner groove  60  via a passage  74  that extends through the piston body  54 . Strategic dimensioning of the arms  38 ,  46  and nozzle assemblies  34  sets the nozzles  35  in an annular space  76  between the casing hanger  16  and wellhead housing  18  when the nozzle assemblies  34  are in the deployed position. As shown, a stream exiting the nozzle  34  can be directed to a shoulder  78  or ledge on the casing hanger  16  so that debris  80  collected on the shoulder  78  may be washed away with fluid being discharged from the nozzle  35 . Further in the example of  FIG. 2 , the fluid supplied for cleaning in the annular space  76  is pressurized fluid in the bore  32  above ball  72 , where the pressurized fluid flows through the upper port  64 , inner groove  60 , and hose  72  prior to being discharged from the nozzles  35 . Optionally, slots  82  are provided in the housing  43  so that pinned connection  48  can slide axially along housing  43  during steps of deploying the nozzle assemblies  34  and when being stowed back onto the debris cleaner  12  and into the running position of  FIG. 1 . An optional method of deployment includes setting the debris cleaner  12  on a lower end of drill pipe  84 , threaded connections between drill pipe  84  and upper end of upper body  26  are illustrated. 
         [0022]    The present invention described herein, therefore, is well adapted to carry out the objects and attain the ends and advantages mentioned, as well as others inherent therein. While a presently preferred embodiment of the invention has been given for purposes of disclosure, numerous changes exist in the details of procedures for accomplishing the desired results. These and other similar modifications will readily suggest themselves to those skilled in the art, and are intended to be encompassed within the spirit of the present invention disclosed herein and the scope of the appended claims.

Technology Classification (CPC): 4