TREA

SYSTEM FOR SUPPORTING COMPONENTS WITHIN A TUBULAR HOUSING OF A WELLBORE

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Information

  • Patent Application
  • 20100200217
  • Publication Number
    20100200217
  • Date Filed
    February 12, 2009
    16 years ago
  • Date Published
    August 12, 2010
    14 years ago
Information
Abstract
A well system comprising a tubular housing, a hanger assembly, and a load member disposed in a recess within the central bore of the housing to support the hanger assembly from the housing. The recess and the load member are configured so that a greater portion of the area of the load member extends into the central bore of the housing as the load member is moved axially in a first direction within the recess.
Description
BACKGROUND

The invention relates generally to a tubular housing used to support an object within the hollow interior of the tubular housing. In particular, the invention relates to a system having a tubular housing, such as a wellhead, to support an assembly, such as a casing hanger, within the tubular housing via a load member that extends between the housing and the assembly.


In the oil and gas industry, pipes and tubing are used to transport oil and/or gas. In a well, pipe and/or tubing may be supported by a tubular housing. For example, a wellhead and a casing hanger disposed within the wellhead may be used to support pipe, known as casing, within a wellbore. Casing is strong steel pipe that is used in an oil and gas well to ensure a pressure-tight connection from the surface to the oil and/or gas reservoir. However, casing can be used to serve many purposes in a well. For example, the casing can be used to protect the wellbore from a cave-in or from being washed out. The casing can also be used to confine production to the wellbore, so that water does not intrude into the wellbore from a surrounding formation or so that drilling mud does intrude into the surrounding formation from the wellbore. The casing can also provide an anchor for the components of the well.


Several sections of casing joined together end-to-end are known as a “casing string.” Because casing serves several different purposes in a well, it is typical to install more than casing string in a well. Casing strings typically are run in a concentric arrangement, similar to an upside-down wedding cake, with each casing string extending further downward into the ground as the center of the arrangement of concentric casing strings is approached. For example, the casing string with the greatest diameter typically is the outermost casing string and the shortest, while the casing string with the smallest diameter typically is at the center and extends the deepest.


The casing hanger typically supports the casing string from a wellhead or a similar structure located near the seafloor. The casing hanger rests on a landing shoulder inside the wellhead. Multiple casing hangers may supported within a single wellhead. However, another method that may be used to support a casing hanger, rather than by using a shoulder of the wellhead, is to use a load ring to support the casing hanger. The load ring may be actuated to extend between the casing hanger and a recess in the wellhead to support the casing hanger.


Unfortunately, problems may occur when installing components in the well below the wellhead. The load shoulder needed to support a casing hanger reduces the diameter of the inner bore of the wellhead that is available to pass objects through the wellhead. Thus, the maximum diameter of a well component that that can be passed through the wellhead is limited by the diameter of the load shoulder. This limitation affects the maximum diameter of the casing string that can pass through the wellhead, as well. This, in turn, reduces the maximum amount of oil and/or gas that can pass through the casing or production tubing at a given time during the operation of the well. Various techniques have been developed to maximize the effective diameter of the inner bore of a wellhead to enable larger objects to pass through the wellhead for wellheads having a given diameter. However, these techniques require complicated mechanisms requiring several components, such as activation members, load members, etc., to function.


Therefore, an improved technique for supporting a component within a tubular housing is desired. The techniques described below may solve one or more of the problems described above.


BRIEF DESCRIPTION

A well system comprising a tubular housing, a hanger assembly, and a load member disposed in a recess within the central bore of the housing to support the hanger assembly from the housing. The recess and the load member are configured so that a greater portion of the area of the load member extends into the central bore of the housing as the load member is moved axially in a first direction within the recess.





DRAWINGS

These and other features, aspects, and advantages of the present invention will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:



FIG. 1 is a cross-sectional view of a wellhead system comprising a casing hanger installed within a high pressure wellhead, in accordance with an exemplary embodiment of the present technique;



FIG. 2 is a detailed cross-sectional view of a portion of the wellhead system, taken generally along line 2-2 of FIG. 1, in accordance with an exemplary embodiment of the present technique;



FIGS. 3-7 are a series of Figures illustrating the installation of the casing hanger into the wellhead; in accordance with an exemplary embodiment of the present technique;



FIG. 3 is a cross-sectional view illustrating the casing hanger being lowered into the high pressure wellhead during the installation process of the casing hanger, in accordance with an exemplary embodiment of the present technique;



FIG. 4 is a cross-sectional view illustrating the casing hanger initially engaging a split ring disposed in a recess within the high pressure wellhead, in accordance with an exemplary embodiment of the present technique;



FIG. 5 is a detailed cross-sectional view of a portion of the casing hanger, taken generally along line 5-5 of FIG. 4, in accordance with an exemplary embodiment of the present technique;



FIG. 6 is a cross-sectional view illustrating the final positions of the casing hanger and split ring in the high pressure wellhead, in accordance with an exemplary embodiment of the present technique;



FIG. 7 is a detailed cross-sectional view illustrating the final positions of the casing hanger and split ring in the high pressure wellhead, taken generally along line 7-7 of FIG. 6, in accordance with an exemplary embodiment of the present technique;



FIG. 8 is a top view illustrating the initial position of the split ring relative to the central bore of the high pressure wellhead, in accordance with an exemplary embodiment of the present technique; and



FIG. 9 is a top view illustrating the final position of the split ring relative to the central bore of the high pressure wellhead, in accordance with an exemplary embodiment of the present technique.





DETAILED DESCRIPTION

Referring now to FIG. 1, the present invention will be described as it might be applied in conjunction with a technique for supporting a first device within the hollow interior of a second device. In the illustrated embodiment, the technique is used in a wellhead system, as represented generally by reference numeral 20, comprising a high pressure wellhead 22 and a casing hanger assembly 24. However, the technique may be used in systems other than a wellhead system. A string of casing (not shown) is connected to bottom of the casing hanger assembly 24. The casing hanger assembly 24 and casing string are lowered into a central bore 26 of the high pressure wellhead 22 by a setting tool (not shown). The setting tool is supported by a string of pipe extending from a derrick or crane located on a platform, such as a drilling ship.


Referring generally to FIGS. 1 and 2, the casing hanger assembly 24 is supported in the central bore 26 of the high pressure wellhead 22 by a load member 28 disposed within a recess 30 from the central bore 26 of the high pressure wellhead 22. The load member 28 is a contractible ring, such as a C-ring. However, the load member 28 may be a series of dogs that may be moved inward into engagement with the casing hanger assembly 24, or some other type of load bearing assembly.


In the illustrated embodiment, the recess 30 is configured to enable the load member 28 to move within the recess 30 along a longitudinal axis 31 of the wellhead 22. In addition, as will be discussed in more detail below, the load member 28 and the recess 30 are configured so that a greater portion of the load member 28 is extended from the recess 30 into the central bore 26 of the wellhead 22 as the load member 28 is moved in a first axial direction within the recess 30.


In FIGS. 1 and 2, the load member 28 is shown in a final position after having moved in the first axial direction from an initial position above the final position shown here. In the illustrated embodiment, the recess 30 has a tapered surface 32 and the load member 28 has a corresponding tapered surface 34 that faces the tapered surface 32 of the recess 30. The tapered surfaces 32, 34 cooperate to drive the load member 28 inward as the load member 28 moves axially from the top of the recess 30 to the bottom in this view. The illustrated embodiment of the recess 30 has a shoulder 36 that limits axial movement of the load member 28. The load member 28 has a corresponding surface 38 that is configured to abut the shoulder 36 of the recess.


The load member 28 has a surface 40 that is used to form a shoulder for the casing hanger assembly 24. In the illustrated embodiment, the surface 40 is tapered. In the illustrated embodiment, the casing hanger assembly 24 has a protrusion 42 that engages the load member 28 when the casing hanger assembly 24 is lowered into the wellhead 22. The protrusion 42 has a surface 44 that faces the surface 40 of the load member 28. In the illustrated embodiment, the surface 44 is tapered. The tapered surfaces 40, 44 engage in sliding engagement as the casing hanger assembly 24 and the load member 28 move axially within the wellhead 22.


A portion of the top surface 40 of the load member 28 extends into the central bore 26 to form a shoulder 46 for supporting the casing hanger assembly 24 within the central bore 26. As will be discussed in more detail below, the portion of the surface 40 of the load member 28 that extends into the central bore 26 is greater when the load member 28 is located in the final position, as shown here in FIGS. 1 and 2, than the portion that extends into the central bore 26 when the load member 28 is located in its initial position prior to axial movement within the recess 30. By minimizing the portion of the surface 40 of the load member 28 that extends into the central bore 26 prior to deploying the casing hanger assembly 24 into the wellhead 22, the diameter available for an object to be deployed into the wellbore below the casing hanger 24 is increased.


Referring generally to FIGS. 3-7, a series of Figures illustrating the deployment of the casing hanger assembly 24 into the high pressure wellhead is presented. The casing hanger assembly 24 is initially located above the wellhead 22 in this view. The casing hanger assembly 24 is then lowered into the high pressure wellhead to be supported by the load member 28.


Referring generally to FIG. 3, as noted above, the casing hanger assembly 24 is lowered into the high pressure wellhead 22 in a first axial direction, as represented by arrow 48. The load member 28 is disposed in an upper portion of the recess 30 of the high-pressure wellhead 22. In the illustrated embodiment, the load member 28 is outwardly-biased to maintain the load member 28 in the upper portion of the recess 30. The load member 28 has an opening 50 extending through the load member 28 and having a diameter, “D1”, which is almost as wide in diameter as the full width of the diameter of the central bore 26 of the wellhead 22. As a result, objects having a diameter almost as great as the full width diameter of the central bore 26 of the wellhead 22 may pass through the load member 28.


Referring generally to FIGS. 4 and 5, as the casing hanger assembly 24 is lowered further into the wellhead 22 it eventually engages the load member 28. With the load member 28 located in the upper portion of the recess 30, the load member 28 initially presents a smaller shoulder 52 to the casing hanger assembly 24 than is present after the load member 28 is displaced axially within the recess 30. Thus, objects having a greater diameter than the final diameter of the opening 50 through the load member 28 may be deployed into the wellbore below the casing hanger 24.


Referring generally to FIGS. 6 and 7, as the casing hanger assembly 24 is lowered onto the load member 28, it drives the load member 28 downward within the recess 30 of the wellhead 22 in a first axial direction, as represented by arrow 54, from the upper portion of the recess to a lower portion of the recess 30. The tapered surfaces 32, 34 of the recess 30 and load member 28 cooperate to urge the load member 28 downward and inward, as represented by arrow 54.


The inward movement of the load member 28 produced by the downward axial movement in the recess 30 results in the shoulder 46 presented by the load member 28 after axial movement being greater in size than the shoulder 52 before axial movement. The top surface 40 of the load member 28 slidingly engages the bottom surface 44 of the protrusion 42 of the casing hanger assembly 24 as the load member 28 is driven in the inward direction 56. In addition, the opening 50 extending through the load member 28 after the inward movement of the load member 28 has a diameter, “D2”, which is smaller in diameter than the initial diameter, D1. In the illustrated embodiment, axial movement of the load member is stopped by the shoulder 36 of the recess 30. In this position, the load member 28 supports the casing hanger assembly 24 from the high pressure wellhead 22.


Referring generally to FIGS. 8 and 9, top views of the load member 28 extending into the central bore 26 of the high pressure well head 22 are presented. As best seen in FIG. 8, the illustrated embodiment of the load member 28 is a split ring that has a gap 56. The initial shoulder 52 presented by the load member 28 in FIG. 8 extends a lesser distance into the central bore 26 than the final shoulder 46 presented by the load member in FIG. 9. In addition, the gap 56 present in FIG. 8 is no longer present in FIG. 9 due to the inward contraction of the load member 28.


While only certain features of the invention have been illustrated and described herein, many modifications and changes will occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the invention.

Claims
  • 1. A well system, comprising: a well housing having a hollow interior comprising a central bore and an annular recess from the central bore, the recess having a tapered surface;a deformable ring adapted to be disposed in the recess of the well housing and extend from within the recess into the central bore, wherein the ring and the tapered surface of the recess are adapted to compress the ring as the ring travels axially from a first portion of the recess to a second portion of the recess to increase ring area within the central bore.
  • 2. The well system as recited in claim 1, wherein the tapered surface of the recess is a conical section that decreases in radius in an axial direction from the first portion of the recess to the second portion of the recess.
  • 3. The well system as recited in claim 1, wherein the ring has a tapered surface that faces the tapered surface of the recess.
  • 4. The well system as recited in claim 1, wherein the ring comprises a surface adapted to support an object from the ring within the central bore.
  • 5. The well system as recited in claim 4, wherein the surface adapted to support an object from the ring within the central bore comprises a seating surface adapted to receive a corresponding surface of the object.
  • 6. The well system as recited in claim 5, wherein the seating surface comprises a conical section that decreases in radius in an axial direction.
  • 7. The well system as recited in claim 1, wherein the well housing is a high-pressure wellhead.
  • 8. The well system as recited in claim 7, comprising a hanger assembly, wherein the hanger assembly is supported by the ring within the high-pressure wellhead.
  • 9. The well system as recited in claim 1, wherein the ring is biased to expand outward when disposed in the recess in the housing.
  • 10. A well system, comprising: a well housing having a hollow interior comprising a central bore and an annular recess from the central bore; anda collapsible ring disposed within the recess of the housing and extending from the recess into the central bore to form a shoulder to support an object disposed within the central bore, wherein the ring is axially movable within the recess between a first axial position and a second axial position, the surface area of the ring within the central bore being greater in the second axial position than in the first axial position.
  • 11. The well system as recited in claim 10, wherein the recess comprises an axially-tapered surface.
  • 12. The well system as recited in claim 11, wherein the ring has a corresponding axially-tapered surface that faces the axially-tapered surface of the recess.
  • 13. The well system as recited in claim 10, wherein the ring comprises a seating surface adapted to receive a corresponding surface of the object.
  • 14. The well system as recited in claim 10, wherein the seating surface comprises a conical section that decreases in radius in an axial direction.
  • 15. The well system as recited in claim 10, wherein the well housing is a high-pressure wellhead.
  • 16. The well system as recited in claim 15, comprising a hanger assembly, wherein the hanger assembly is supported by the ring within the high-pressure wellhead.
  • 17. The well system as recited in claim 10, wherein the ring is biased to expand outward when disposed in the recess in the housing.
  • 18. A wellhead system, comprising: a well housing having a hollow interior comprising a central bore and an annular recess from the central bore, the recess having a tapered surface;a hanger assembly; anda split ring adapted to be disposed in the recess of the well housing and extend from within the recess into the central bore to support the hanger assembly, wherein the tapered surface of the well housing is configured to collapse the split ring when the hanger assembly is disposed on the split ring to be supported by the split ring.
  • 19. The wellhead system as recited in claim 18, wherein the split ring is disposed in a first axial position in the recess and driven to a second axial position by the hanger assembly.
  • 20. The wellhead system as recited in claim 19, wherein the area of the split ring within the central bore is greater when the split ring is disposed in the second axial position than when the split ring is disposed in the first axial position.
  • 21. The wellhead system as recited in claim 19, wherein the radius of the recess is greater in the region corresponding to the first axial position of the split ring than in the region corresponding to the second axial position.
  • 22. The wellhead system as recited in claim 18, wherein the split ring has a tapered surface that faces the tapered surface of the recess.
  • 23. The wellhead system as recited in claim 18, wherein the split ring comprises a surface adapted to support the hanger assembly facing the hanger assembly.
  • 24. The wellhead system as recited in claim 23, wherein the surface adapted to support the hanger assembly comprises a conical section.