Latch Assembly For Well Tools

Abstract

A latch assembly which is designed to be inserted into the bore of a well tool having a preexisting landing shoulder and a latching groove spaced below the shoulder for engagement by cooperating seating and gripping elements of a collet member which is slidably supported on a mandrel. The mandrel carries a split latch ring for engagement with the collet member in response to relative movement of the mandrel in order to effect release of the latch assembly from the well tool when desired.

Description

In the operation of oil and gas wells it is usually necessary to equip the wells with various types of tools used in completion, treating and producing operations. Certain of the tools may be intended for temporary use and then retrieved, and others are designed to be left for long periods of time but to be removable when required in the course of operation of the well. Such tools include various types of packers, anchors, testing tools, and others well known in the oil and gas industry. Sometimes two or more different tools may be run together and set or operated sequentially or one tool may be run following another already in place in the well and secured thereto. Frequently it is desired that the several tools may be separately retrievable. Heretofore such operations have involved the use of running and retrieving tools which are relatively complicated in structure, difficult to operate, and subject to breakage and other undesirable properties.

The present invention is directed to an improved form of latch assembly which overcomes the disadvantages of prior art tools, and which is adapted to be used for releasably securing one tool to another, for retrieving tools in place in a well, and for use in conducting other tool-running and retrieving operations in a well.

The tool in accordance with this invention is designed for use with other tools which are initially equipped with a tubular support structure, which can function as a landing nipple and which is provided with an internal landing shoulder and an annular latch recess spaced below the landing shoulder. Such shoulder and recess may be provided in a landing nipple or subforming a part of a well tool or may be provided in the bore wall of the central body or mandrel of a packer, well anchor or any other well tool which is supported on a tubular body.

The latch assembly in accordance with this invention includes a central support member or mandrel which has a pair of longitudinally spaced external enlargements providing shoulders or abutments spaced apart by approximately the same spacing as exists between the landing shoulder and latching recess of the tool to be connected to the latch assembly. A collet member is slidably mounted on the mandrel and includes a carrier ring which is adapted to seat on the landing shoulder. Depending from the ring is a plurality of resilient latch fingers the free ends of which are formed to provide enlarged tips which will be disposed in registration with the latch recess in the receiving tool body when the carrier ring is seated on the landing shoulder. The tips are disposed to be urged into and released from latching engagement with the recess respectively in response to relative upward and downward movement of the mandrel.

Means are also provided on the latch assembly to hold the collet member in released position when it is desired to withdraw the assembly without removing the tool to which it is attached. This means includes a split latch ring mounted on the mandrel above the carrier ring on a supporting shoulder and carrying external ratchet teeth engageable with complimentary ratchet teeth provided in the bore of the collet carrier ring when the mandrel is moved downwardly relative to the collet member to effect release of the collet member from the well tool to which it is anchored. The split latch ring is initially held in inactive position on the supporting shoulder by a keeper collar releasably secured to the mandrel by means of a shear pin or the like which can be broken by jarring downward on the mandrel. Thereupon further downward movement of the mandrel will move the latch ring into engagement with the carrier ring of the collet member.

Various other objects and advantages of this invention will become more readily apparent from the following detailed description when read in conjunction with the accompanying drawing which illustrates a useful embodiment in accordance with this invention.

In the drawing:

FIG. 1 is a longitudinal quarter sectional view of the latch assembly in process of being inserted into the support body of a well tool to which it is to be attached;

FIG. 2 is a view similar to FIG. 1 showing the latch assembly secured in place in the well tool;

FIG. 3 is a view similar to the preceding views showing the latch assembly in process of being removed from the well tool;

FIG. 4 is a quarter sectional view showing the latch assembly connecting one well tool to another in place in a well;

FIG. 5 is a view similar to FIG. 4 showing the latch assembly in process of being released from the lower tool to permit withdrawal of the latch assembly with the upper tool;

FIGS. 6 and 7 are cross-sectional views taken respectively on lines 6--6 and 7--7 of FIG. 4; and

FIGS. 8 and 9 are cross-sectional views taken respectively on lines 8--8 and 9--9 of FIG. 5.

Referring first to FIGS. 1 to 3, there is shown a portion of a tubular body B which may be the supporting body or mandrel of a well packer, an anchor, a landing nipple, or any other conventional well tool. Body B is provided with a central bore 10 constructed and arranged for use with the latch assembly of this invention by being provided internally with an annular landing shoulder 11 spaced above an annular latch recess 14 defined by bevelled upper and lower end walls 15 and 16, respectively.

The latch assembly, designated generally by the letter L is dimensioned to be insertable in bore 10 and comprises an elongate mandrel 18, the lower end of which is enlarged in two steps to define an upper bevelled shoulder 20 and a lower bevelled shoulder 22 terminating in a cylindrical enlargement 24 dimensioned to be freely slidable in bore 10. Enlargement 24 may carry a flexible seal member or packer 26 when it is desired that the tool should also function to seal off the space between enlargement 24 and the wall of bore 10.

At a point above shoulder 20 mandrel 18 is enlarged to a diameter corresponding to that of shoulder 20 and this enlargement 27 defines an upwardly facing annular shoulder 28 about the mandrel. The linear spacing between shoulders 22 and 28 is made approximately the same as that between shoulder 11 and recess 14. Slidably disposed about mandrel 18 is a collet member, designated generally by the letter C, which includes a carrier ring 30 the bore of which is provided with buttress or ratchet teeth 32, the lowermost one of which forms an abutment engageable with upper shoulder 28 to limit relative downward movement of collet member C on mandrel 18. Depending from carrier ring 30 is a plurality of closely spaced flexible fingers 34, the lower ends of which terminate in radially enlarged tips 36 having upper and lower bevelled end surfaces 37 and 38, respectively. Carrier ring 30 has a greater thickness than fingers 34 to provide an external downwardly facing annular shoulder 40 at the juncture of fingers 34 with the carrier ring. Shoulder 40 is adapted to seat on shoulder 11 and when so seated to position collet tips 38 in registration with recess 14 (FIG. 2).

A portion 42 of mandrel 18 above shoulder 28 is reduced in diameter to define the upwardly facing bevelled shoulder 44. A split clutch ring 46 (see FIGS. 6 and 8) is slidably disposed about portion 42 and initially rests on shoulder 44. Clutch ring 46 is provided with external buttress or ratch teeth 48 adapted to engage teeth 32 in the carrier ring of the collet member when clutch ring 46 is forced downwardly into the bore of carrier ring 30, as will be described hereinafter.

A keeper collar 50 surrounds clutch ring 46 to hold the latter in place on shoulder 44 and collar 50 is releasably secured to mandrel 18 at a point above portion 42 by means of a shear pin 52 which is adapted to be broken when desired by jarring blows on mandrel 18 applied in the conventional manner through a running string. The uppermost end of mandrel 18 is provided with a fishing head 54 for connection to a conventional overshot or similar tool O forming a part of a conventional running string by which the tool may be run or retrieved as desired.

As illustrated in FIGS. 1 to 3, mandrel 18 is shown as having an axial bore 19 which is closed off at its upper end by fishing head 54. However, depending upon the particular service to be performed by the tool, ports (not shown) may be provided in the upper end of the mandrel to permit flow of fluids through the tool, particularly when provided with a packer 26 to seal off between mandrel 18 and the wall of bore 10.

FIGS. 1 and 2 illustrate stages in operation of the tool as a latch for grasping a tool in place in a well to serve as a means by which the tool may be removed from the well. As shown, the latch, suspended from overshot O is inserted into bore 10. As the mandrel enters the latter enlargement 36 will engage the upper end of body B temporarily stopping collet member C and allowing mandrel 18 to move downwardly relative to the collet member by a distance sufficient to move shoulders 20 and 22 below tips 36 which will then be free to swing inwardly toward the reduced diameter portion of mandrel 18 between shoulders 20 and 28 so as to be able to enter bore 10. Downward movement of the collet member may now continue until shoulder 40 on carrier ring 30 engages landing shoulder 11, at which point tips 36 will be disposed opposite recess 14 (FIG. 2). Slight upward pull on the running string will act through engagement of shoulder 22 with end surfaces 38 of tips 36 to force the latter tightly into recess 14. Thereupon, upward pull applied to mandrel 18 will be transmitted to body B to remove the latter from the well.

If for any reason the tool-comprising body B cannot be pulled, and it becomes necessary to retrieve the latch tool, clutch ring 46 provides a safety device for this purpose. Retrieval of the latch tool may be accomplished by jarring down on the upper end of mandrel 18 with force sufficient to break shear pin 52. Thereupon, as seen in FIG. 3, mandrel 18 may be lowered relative to the collet member until enlargement 24 moves below tips 36, whereupon the tips are free to swing out of recess 14. The relative downward movement of the mandrel will carry clutch ring 46 down into the bore of carrier ring 30 and force engagement of ratchet teeth 48 with ratchet teeth 32, thereby locking enlargement 24 in its lowered position relative to tips 36. Thereupon upward pull applied to mandrel 18 will be effective to pull the latch assembly out of body B.

FIGS. 4 and 5 illustrate an application of the latch assembly to serve as a connector between a tool, such as a conventional well packer P already in place in a well casing W and a second well tool T of any design which it is desired to position above the packer and which may be retrieved, if desired, without disturbing the packer.

In this application, tool T is run on the upper end of mandrel 18 and a fishing head 54 secured to the upper end of tool T. In this case, it may be assumed that it is desired to permit fluid flow between the portions of the well above and below the packer and mandrel 18 will be provided with appropriate circulation ports indicated in broken lines at 55. In the event fluid flow is desired through tool T, it will be understood that suitable ports or passages (not shown) will be provided in mandrel 18 and tool T.

Body B of the packer will have been provided with landing shoulder 11 and recess 14. Tool T secured to the upper end of mandrel 18 will be run into the well and the latch tool inserted in the bore of the packer body and latched therein as previously described. FIG. 4 shows the tools in place.

FIG. 5 corresponds to FIG. 3 illustrating the positions of the parts when effecting retrieval of tool T and the latch assembly from their connection with packer P. The operation will be as described previously in connection with FIG. 3.

It will be understood also, that the latch assembly, as previously described, may be employed to withdraw both tool T and packer P if desired.

From the foregoing it will be evident that the latch assembly herein described comprises a comparatively simple, easily operated assemblage which is capable of multiple uses in connection with the equipping and operation of wells.

It will be understood that various alterations and modifications of the illustrative embodiments may be made within the spirit of this invention.

Claims

What I claim and desire to secure by Letters Patent is:

1. For use in combination with a well tool having an axial bore, the wall of said bore having an internal landing shoulder and an annular latch recess spaced below said landing shoulder, a latch and retrieving assembly comprising:

a. a mandrel insertable in said bore;

b. upper and lower abutments on the mandrel spaced to substantially match the spacing between said landing shoulder and said recess;

c. a collet member slidably mounted about said mandrel, said collet member including:

i. a carrier ring disposed above said upper abutment and seatable on said landing shoulder;

ii. a plurality of elongate resilient fingers depending from said carrier ring and terminating in radially enlarged tips disposed in registration with said recess when said carrier ring is seated on said landing shoulder, said tips cooperating with said lower abutment to latch into and to be released from said recess respectively in response to relative upward and downward movement of said mandrel;

d. clutch means releasably secured to said mandrel above said collet member and releasable in response to relative downward jarring of the mandrel to engage said collet member whereby to effect release of said fingers from said recess; and

e. means carried by said mandrel for connection to a running tool string.

2. The assembly of claim 1 including an annular resilient seal element mounted about said mandrel below said lower abutment for slidable sealing engagement with the wall of said bore.

3. The assembly of claim 1 wherein said mandrel has an axial bore extending therethrough.

4. The assembly of claim 1 wherein said last mentioned means comprises an enlarged fishing head.

5. For use with a well tool having an axial bore, the wall of said bore having an internal landing shoulder and an annular latch recess spaced below said landing shoulder, a latch and retrieving assembly comprising:

a. a mandrel insertable in said bore;

b. upper and lower abutments on the mandrel spaced to substantially match the spacing between said landing shoulder and said recess;

c. a collet member slidably mounted about said mandrel, said collet member including:

i. a carrier ring disposed above said upper abutment and seatable on said landing shoulder;

ii. a plurality of elongate resilient fingers depending from said carrier ring and terminating in radially enlarged tips disposed in registration with said recess when said carrier ring is seated on said landing shoulder, said tips cooperating with said lower abutment to latch into and to be released from said recess respectively in response to relative upward and downward movement of said mandrel;

iii. ratchet teeth in the bore of said carrier ring;

d. a split clutch ring slidably disposed about said mandrel above said carrier ring, said clutch ring having external ratchet teeth engageable with those in said carrier ring when said mandrel is moved downwardly to the position releasing said tips from said recess;

e. releasable means initially securing said clutch ring at a point spaced from said carrier ring; and

f. means carried by said mandrel for connection to a running tool string.