Title:
HYDRAULIC SET LINER HANGER
United States Patent 3608634


Abstract:
A liner hanger employing a hydraulically actuated setting tool structure which is removable substantially entirely after setting of the hanger leaving a minimal amount of hanger structure in the well. A dog-type latch provides an improved releasable connection between the setting tool and the hanger and a reset spring is provided in the event of premature setting of the hanger to enable release of the hanger for movement to the desired location.



Inventors:
COCHRAN CHUDLEIGH B
Application Number:
05/021122
Publication Date:
09/28/1971
Filing Date:
03/19/1970
Assignee:
BROWN OIL TOOLS INC.
Primary Class:
Other Classes:
166/124, 166/212
International Classes:
E21B23/04; E21B23/06; E21B43/10; (IPC1-7): E21B43/10
Field of Search:
166/124,125,181,182,208,212
View Patent Images:
US Patent References:



Primary Examiner:
Leppink, James A.
Claims:
What I claim and desire to secure by Letters Patent is

1. A liner hanger, comprising,

2. A liner hanger according to claim 1, wherein said expander surfaces are of stepped configuration; and wherein said slips have stepped inner surfaces of complementary configuration.

3. A liner hanger according to claim 1, wherein said cage member comprises a ring to which said slips are pendently supported by flexible arm means, and wherein a keeper collar is mounted on said body to slidably receive the free ends of said slips.

4. A liner hanger according to claim 1, wherein said cooperating means comprises:

5. A liner hanger according to claim 1, wherein said latching collar carries longitudinally spaced seals defining a cylinder surrounding said mandrel; and ports through the wall of said mandrel communicating with said cylinder.

6. A liner hanger according to claim 1, wherein said releasable latch means comprises:

7. A liner hanger, comprising:

Description:
Liner hangers are employed to secure an inner pipe string or liner to an outer pipe string or casing in a well bore generally preparatory to cementing the liner in place in the well bore to seal off the surrounding earth formations.

Generally speaking, the liner hanger is secured to the upper end of the liner string and is run on a setting tool assembly which functions to secure the liner to the surrounding casing and to aid in the subsequent cementing operation. In more conventional liner hangers, substantial portions of the setting assembly form integral parts of liner hanger and must remain in the well, thereby substantially increasing the cost of the liner hanger to the well operator, as well as increasing the complexity of the operations involved in setting the hanger and conducting the subsequent cementing operations.

The present invention is directed to a greatly simplified liner hanger in which the setting tool is actuated by hydraulic pressure to anchor the liner to the surrounding casing, and is retrievable substantially in its entirety when setting is completed leaving only minimal hanger structure in the well.

In accordance with a preferred embodiment of this invention, the hanger body employs a multicone and slip construction which greatly reduces the overall length of the hanger itself. The setting tool includes a mandrel which carries a setting collar slidably mounted thereon and releasably attached to the hanger setting sleeve by a positive dog-type latch which assures against premature setting of the hanger during running. The setting collar embodies a cylinder communicating with the bore of the mandrel for admitting pressure fluid to actuate the hanger. A floating nut provides a releasable connection between the mandrel and the hanger which upon release, enables the setting tool to be withdrawn from the hanger. Spring means is provided in compression between the mandrel and the setting collar which functions to permit release of the hanger in the event the hanger is prematurely set during running to thereby allow the running of the hanger to be resumed without requiring the hanger to be withdrawn from the well for resetting.

Other and more specific objects and advantages of this invention will become more readily apparent from the following detailed description when read in conjunction with the accompanying drawings which illustrate one embodiment of the invention and a modification thereof.

IN THE DRAWING:

FIGS. 1A, 1B, and 1C, together, comprise a longitudinal quarter-sectional view of the liner hanger and setting tool assembly, together with some related parts employed in the liner cementing operation, but which do not themselves form a part of this invention, the tool parts being shown in the running position;

FIG. 2 is a longitudinal quarter-sectional view corresponding to FIG. 1A showing the hanger set in the surrounding well casing;

FIG. 3 is a view similar to FIG. 2 showing the setting tool released from the hanger body;

FIG. 4 is a view similar to FIG. 3 showing the setting tool completely released from the hanger preparatory to withdrawal of the setting tool from the well;

FIG. 5 is a view similar to FIG. 4 showing the hanger in place and cemented, the setting tool being completely removed;

FIG. 6 is a longitudinal quarter-sectional view of modified form of the liner hanger, the parts being shown in the running-in position;

FIG. 7 is a view generally similar to FIG. 6 showing the hanger in the set position with the setting tool in the same position as seen in FIG. 2; and

FIGS. 8 and 9 are cross-sectional views taken on lines 8--8 and 9--9 respectively, of FIG. 1A.

Referring to the drawing, more particularly to FIGS. 1A to 1C, the hanger structure comprises the liner hanger, per se, designated generally by the letter A, and the setting tool structure designated generally by the letter B, which is secured to the hanger structure and by means of which the tool string is run inside a well casing C, to which the hanger A is to be attached.

Liner hanger A comprises a tubular body 10, the lower end of which has a threaded socket 11 for connection of the hanger to the upper end of a pipe string L which constitutes the liner to be anchored to the casing C. The exterior of hanger body 10 is provided with a stepped surface, the portions of which define successive upwardly and outwardly tapering frustoconical surfaces 12--12, there being at least two of these steps on the exterior of the body 10 to form expander cones. Surrounding body 10 is a tubular cage 14 having a plurality of openings or windows 15 in which are mounted pipe-gripping slips 16, having their inner surfaces stepped in a manner complementary to the stepped expander surfaces 12, the complementary surfaces on the interior of the slips being indicated by the numerals 17--17. Slips 16 are provided with buttress teeth 18 on their outer surfaces for biting into the wall of casing C, when the slips are moved outwardly and upwardly relative to hanger body 10. Downward movement of the slips with cage 14 relative to body 10 will cause slips to retract out of gripping engagement with casing C. Cage 14 is held in its slip-retracting down position relative to hanger body 10 by means of shear pins 20 which secure the cage to body 10. The upper end of cage 14 is secured to extension sleeve 22 which is termed the setting sleeve in this description.

Setting tool B comprises the tubular mandrel 24, the upper end of which is externally threaded for connection by means of a coupling 25, to a running pipe string P and the lower end of which is connected to a seal nipple 28 carrying downwardly opening cup seals 30 for sealing off the annular space between the seal nipple and the wall of liner L (FIG. 1B). Mandrel 24 includes a sub 32 threadedly received at its upper end in a threaded socket 33 forming a portion of the mandrel and at its lower end in a socket 34 carried by the upper end of the seal nipple, thus forming the connection between the latter and the mandrel. The ends of sockets 33 and 34 define spaced-apart external shoulders 35 and 36, respectively.

The exterior of sub 32 between shoulders 35 and 36 is provided with one or more longitudinally extending radial splines 37 on which a floating nut 38 is slidably mounted. The exterior of nut 38 carries a section of left-hand threads 39 adapted to mate with a complimentary section of threads 40 formed in the inner wall of hanger body 10. By means of the left-hand thread arrangement, rotation of the mandrel in the right-hand direction will cause nut 38 to move upwardly on splines 37 relative to hanger body 10 to effect release of this connection between the mandrel and the hanger body when the nut has cleared threads 40 (FIG. 3). Mounted about sub 32 between shoulder 35 and the upper end of splines 37 is an antifriction bearing 41 which is supported between shoulder 35 and a bearing shoulder 42 formed by the upper end of hanger body 10. This bearing arrangement aids rotation of the mandrel relative to the liner hanger during operation of the tools.

A setting collar 44 is slidably mounted about the upper portion of mandrel 24 and carries spaced-apart internal packings 45--45 slidably sealing with the exterior of the mandrel to define between them a cylinder 46 which is in communication with the bore of the mandrel via one or more ports 47 which extend through the wall of the mandrel. Setting collar 44 is biased downwardly relative to the mandrel by means of a coil spring 48 disposed about the upper end portion of mandrel 24 in compression between the upper end of collar 44 and coupling 25.

The lower end portion of collar 44 is enlarged in diameter and is connected to a tubular cage 49 concentrically spaced from the exterior of mandrel 24 and dimensioned to extend between the latter and the upper end of setting sleeve 22. Cage 49 is provided with a plurality of angularly spaced radial windows 50 in which latching dogs 51 are mounted for radial movement. Dogs 51 are dimensioned to a radial thickness somewhat greater than that of the wall of cage 49 so as to present shoulders exteriorly or interiorly of cage 49 depending on the direction in which the dogs are moved in windows 50. A latching sleeve 52 is mounted in the bore of cage 49 and is provided near its lower end with an external recess 53 adapted to receive dogs 51 when moved upwardly inside cage 49 into registration with the dogs. Latching sleeve 52 is initially held in its upper position (FIG. 1A) by means of shear screws 54 connecting the sleeve to the cage. In this position sleeve 52 forces dogs 51 outwardly of the cage and the upper end of setting sleeve 22 is provided with an internal annular recess 55 to receive the thus outwardly projected dogs. In the position shown in FIG. 1A, the dogs 51 provide a positive connection between the running collar and the setting sleeve which provides greater assurance against untimely release of the setting tool from the liner hanger during running of the tools than is afforded by the more conventional shear pins commonly used for a corresponding purpose.

As the liner hanger is commonly employed in conjunction with tools for cementing the liner in the well bore after it is secured to the casing, FIG. 1B shows a conventional cementing plug 60 releasably secured to the lower end of seal nipple 28, and FIG. 1C illustrates a conventional landing collar 61 mounted in the bore of casing C and provided with a central opening 62 adapted to be closed by means of a ball 63 (shown in broken lines) which is pumped down through the running string for closing off the casing bore to permit buildup of fluid pressure inside the liner hanger setting tool for purposes of setting the hanger as well as for other purposes in connection with the cementing operation.

It will be understood that seal nipple 28, cementing plug 60 and landing collar 61, do not, per se, form parts of the liner hanger structure of this invention, except insofar as they illustrate one means by which fluid pressure can be directed into cylinder 46 of the setting collar. Other means for this purpose will be readily evident to those skilled in the art to which the present invention pertains.

In operation, the liner hanger A connected to the top of liner L and with setting tool B connected thereto with the respective parts in the positions shown in FIGS. 1A to 1C, will be run into casing C on pipe string P. In this stage of operation running collar 44 will be secured to setting sleeve 22 and mandrel 24 connected to hanger body 10 by means of floating nut 38.

When the tools have reached the desired point inside casing C, ball 63 will be dropped through the bore of pipe string P and pumped down with fluid, such as mud, to its seat on landing collar 61 closing port 62, sealing off the casing, and allowing fluid pressure to build up inside the bore of mandrel 24. The pressure will be transmitted through ports 47 into cylinder 46 and exert upward pressure on collar 44 and thence through setting sleeve 22 to slip cage 14 with sufficient force to break shear screws 20 (FIG. 2), moving the cage upward relative to body 10. This relative upward movement of the cage will force slips 16 upwardly and outwardly over expander surfaces 17--17 until teeth 18 are caused to bite strongly into the wall of casing C, thereby setting the liner hanger and securing the liner to the casing. The upward movement of the setting collar on mandrel 24 will strongly compress spring 48. If for any reason the slips on the liner hanger have set prematurely during the running of the tools, it is only necessary to pick up on the running string, whereupon the force of the compressed string 48 will act to push setting collar 44, setting sleeve 22 and slip cage 14 downwardly relative to the mandrel to thereby push slips 36 downwardly and inwardly to their retracted positions, freeing the tools for further downward movement as may be required. The continued engagement of dogs 51 in recess 55 provides a positive connection between the running collar and the liner hanger which enables the necessary manipulation of the tools with assurance against premature release of the setting tool from the liner hanger.

When the hanger is firmly set, running string P will be rotated in the right-hand direction causing floating nut to move upwardly to the position releasing it from its connection to hanger body 10 (FIG. 3), thereby freeing the setting tool and its appended cementing tools for manipulation as may be required in conducting the operations for cementing the liner in the well. These operations will generally require some relatively short longitudinal movements of the setting tool while the cement is being placed and excess cement circulated out of the well.

Thereafter, to effect removal of the setting tool and its appended seal nipple, the other cementing tools being left in the well, upward pull will be applied through the running string to the mandrel to pull the latter upwardly. Running collar 44 will remain stationary through its connection to setting sleeve 22 which will be anchored to the casing wall by slips 16. The resulting relative upward movement of mandrel 24 will bring a shoulder 65 on the exterior of the mandrel into abutting engagement with the lower end of latching sleeve 52 (FIG. 4) with sufficient force to break shear pins 54 and raise sleeve 52 upwardly sufficiently to place recess 53 in registration with dogs 51. This will free the latter to retract from recess 55, thereby releasing collar 44 from setting sleeve 22. The entire setting tool assembly may now be withdrawn from the well leaving only the relatively short liner hanger in the well as best seen in FIG. 5, where it is shown cemented to the casing.

By providing the stepped conical surfaces on the hanger body, the overall length of the hanger will be substantially reduced as compared with more common designs and it will be evident that minimal hanger structure will be left in the well while the entire setting tool will be withdrawn and may be reused in its entirety with other hangers, thereby greatly reducing the cost to the user.

FIGS. 6 and 7 illustrate a modification of the liner hanger involving essentially a modified design of the slip cage and slips. In all other respects the parts are identical with those in the principal embodiment and bear the same numbers.

In this modification the slip cage comprises a ring 114 to which slips 116 are pendently connected by spring arms 115. The slips have stepped internal surfaces 117 complementary to the stepped expander surfaces 12--12. The lower ends of the slips have downwardly and inwardly tapering surfaces 118 adapted to be received in a keeper collar 119 having a tapered inner surface 120 matching the taper of slip surfaces 118. Keeper collar 119 serves to hold the slips inwardly against expander surfaces 12--12 during the longitudinal movements of the slip cage during setting and releasing movements of the slips and to prevent premature engagement with the casing while the tools are being run into the casing. The operations of the setting tool in setting the hanger and in effecting release of the setting tool from the hanger are otherwise identical with the operations described above in connection with the first-described embodiment.

It will be evident that numerous changes and modifications may be made in the details of the illustrative embodiments without departing from the disclosed invention.