U.S. patent number 3,851,706 [Application Number 05/406,764] was granted by the patent office on 1974-12-03 for well packer and retriever.
This patent grant is currently assigned to Dresser Industries, Inc.. Invention is credited to Gary D. Ellis.
United States Patent |
3,851,706 |
Ellis |
December 3, 1974 |
WELL PACKER AND RETRIEVER
Abstract
A well packer to be set in a casing has a cylindrical mandrel
with a resilient packer unit encircling the mandrel which is
radially expandable into contact with the casing when
longitudinally compressed. A drive cylinder is secured to the
mandrel below the packer unit to support the unit. A lower cylinder
encircles the mandrel to bear against the top of the packer unit
and is freely movable longitudinally on the mandrel. A hollow
cylindrical bidirectional grip has beveled generally parallel ends
with toothed shoulders adjacent to opposite extremities of the
beveled ends. The grip is mounted on the mandrel and bears on the
lower cylinder as to be tilted into engagement with the casing but
normally is resiliently biased toward an untilted attitude. An
upper cylinder encircles the mandrel and is slidably positioned
thereon above the grip. Forces acting upward on the mandrel and
downward on the upper cylinder apply a setting force to the grip
which force is transmitted through the packer unit whereby the grip
tilts toward and becomes wedged between opposite sides of the
casing as the packer unit is forced into casing contact to seal the
annulus between the mandrel and the casing.
Inventors: |
Ellis; Gary D. (Dallas,
TX) |
Assignee: |
Dresser Industries, Inc.
(Dallas, TX)
|
Family
ID: |
26975886 |
Appl.
No.: |
05/406,764 |
Filed: |
October 15, 1973 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
307696 |
Nov 17, 1972 |
3818987 |
|
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Current U.S.
Class: |
166/178 |
Current CPC
Class: |
E21B
33/1295 (20130101); E21B 33/1292 (20130101); E21B
23/06 (20130101) |
Current International
Class: |
E21B
33/12 (20060101); E21B 23/06 (20060101); E21B
33/129 (20060101); E21B 23/00 (20060101); E21B
33/1295 (20060101); E21b 023/00 () |
Field of
Search: |
;294/86.25 ;81/3
;166/178,123 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Brown; David H.
Attorney, Agent or Firm: Van Winkle; Roy L. Caddell; Michael
J.
Parent Case Text
This is a division of application Ser. No. 307,696 filed Nov. 17,
1972, now U.S. Pat. No. 3,818,987.
Claims
The embodiments of the invention in which an exclusive property or
privilege is claimed are defined as follows:
1. Release means for a well packer set in a casing with a hollow
cylindrical mandrel extending through a resilient packer unit which
is radially forced into contact with said casing by longitudinal
compression between a drive cylinder secured to said mandrel below
said packer unit wherein a hollow cylindrical grip having beveled
generally parallel ends with toothed shoulders adjacent to opposite
extremities of said beveled ends is tilted into wedging engagement
with said casing by a force transmitted from said packer unit by a
cylindrical spacer engaging the bottom of said grip which
comprises:
a. means to release said drive cylinder from said mandrel, and
b. structure including means on said mandrel to apply an upward
force to the bottom of said grip at a location directly beneath the
upper of said shoulders upon upward movement of said mandrel
relative to said grip to release said grip.
Description
This invention relates to tools for oil wells and the like, and
more particularly to a well packer and a retrieving system
therefor.
A packer is used in oil and gas operations to seal the zone above
the packer from the zone below the packer in a well bore. For
example, after a well casing has been set and the well has been
logged to define the features of significance in the strata through
which the well bore extends, a packer is then lowered into the well
and located at a selected depth. For casing perforating and testing
of a zone spanned by stratum of interest, one packer may be
positioned at the top of the zone and another well packer may be
positioned at the bottom of the zone. This isolates the zone for
testing production after perforation. Packers are also used in
cementing and fracturing operations and the like.
Heretofore, pneumatic, hydraulic, and mechanical packers have been
used. The first two may be likened to an inflated ring using as a
pressurized fluid either air or liquid. Mechanical packers are set
in place by the mechanical displacement of packing components as
distinguished from use of a pressurized medium.
One of the requirements of a satisfactory well packer is to be able
to set it securely at a desired depth. When a packer is no longer
needed, it must be removed. A retrieving system is desired that
will facilitate removal of the packer in a relatively simple
operation without loss of the packer or without damage to
casing.
The packer of the present invention is an improvement over the
packer disclosed in U.S. Pat. No. 3,548,936. It has a bidirectional
grip to hold the packer in place opposing equally both upward and
downward directed forces. Further, the packer of the present
invention is provided with structure for mechanically unsetting the
bidirectional grip to release the packer.
More particularly, in accordance with the invention there is
provided a packer with a cylindrical mandrel encircled by a
resilient packer unit which is radially deformable into contact
with well casing when longitudinally compressed. A drive cylinder
is secured to the mandrel below said packer unit to support the
packer unit. A spacer encircles the mandrel to bear against the top
of the packer unit and is movable longitudinally on the mandrel. A
hollow cylindrical grip having beveled generally parallel ends with
toothed shoulders adjacent to opposite extremities of the beveled
ends is mounted on the mandrel and bears on the spacer as to be
tilted into engagement with the casing but normally is resiliently
biased toward an untilted attitude. An upper cylinder encircles the
mandrel and is slidably positioned thereon above the grip whereby
forces acting upward on the mandrel and downward on the upper
cylinder apply a setting force to the grip which force is
transmitted through the packer unit to tilt and wedge the grip
between opposite sides of the casing as the packer unit seals the
annulus between the mandrel and the casing. Wedge retainer means
between the upper cylinder and mandrel permits downward movement
and prevents upward movement of the upper cylinder with respect to
the mandrel thereby locking the packer in set configuration.
In a further aspect of the invention, a downward opening slot
opposite the lower toothed shoulder of the grip receives the end of
a grip release bar supported on the spacer. A release lug on the
surface of the mandrel below the bar cooperates with a releasable
means coupling the mandrel and spacer which permits limited upward
movement of the mandrel relative to the spacer for releasing the
grip from the set configuration by driving the bar by the mandrel
lug against the end of the slot in the grip.
In a further aspect of the invention, release structure is provided
wherein a movable captured shear resistant element in recesses near
the bottom of the packer spans a common boundary between the
mandrel and drive cylinder. An insert cylinder supported by the
mandrel has an outward facing peripheral groove dimensioned to
accommodate the shear resistant element and normally is restrained
with its groove below the bottom of the element to maintain capture
of the element. Bottom structure secured to the drive cylinder
supports the insert cylinder and has vertical internal ribs
circumferentially arrayed below the insert cylinder of internal
diameter about the same as the internal diameter of the insert
cylinder and separated by vertical recesses. A tubing operated hook
insertable down through said mandrel may engage the bottom of the
insert cylinder only when aligned with the recesses to move the
insert cylinder groove into registration with the shear resistant
element, releasing the mandrel from the drive cylinder followed by
release of the tool upon upward movement of the mandrel.
For a more complete understanding of the invention and for further
advantages thereof, reference may now be had to the following
description taken with the accompanying drawings, in which:
FIG. 1 is a partial cross section of a packer for mechanically
setting a bidirectional grip in a casing;
FIG. 2 is an enlarged longitudinal cross section of the upper
portion of the packer of FIG. 1;
FIG. 3 is a similar section of the middle portion of the well
packer of FIG. 1;
FIG. 4 is a similar section of the lower portion of the well packer
of FIG. 1;
FIG. 5 is a transverse sectional view of a well packer taken along
the line 5--5 of FIG. 2;
FIG. 6 is a longitudinal sectional view of a split ring retainer
only as taken along line 6--6 of FIG. 5;
FIG. 7 is a longitudinal sectional view of the grip 38 of FIGS. 1
and 2;
FIG. 8 is a partial view of the side of the well packer showing the
grip release lug;
FIG. 9 is a longitudinal sectional view of the lock body of FIG.
4;
FIG. 10 is a longitudinal cross-sectional view of the lower end of
the packer guide body and dog retainer of FIG. 4;
FIG. 11 is a transverse cross-sectional view of the guide body
taken along line 11--11 of FIG. 4;
FIG. 12 is a cross-sectional view taken along line 12--12 of FIG.
4;
FIG. 13 is a longitudinal partial cross-sectional view of the lower
end of the packer with a retriever in position to engage the packer
to unseat the packer;
FIG. 14 is a transverse sectional view taken along line 14--14 of
FIG. 13;
FIG. 15 is a partial sectional view of a hydraulic setting adapter;
and
FIG. 16 is a partial sectional view of a mechanical setting
adapter.
DESCRIPTION OF THE PREFERRED EMBODIMENT
FIGS. 1-8 illustrate a well packer embodying the present invention
wherein a hollow cylindrical mandrel 10 extends the length of the
packer from the upper end 12 to the lower end 14. A top connection
16 is threaded onto end 12. Top connection 16 has internal threads
18 for receiving a tool setting mechanism (not shown).
A mandrel slip retainer 22 is mounted concentric with the mandrel
10. Retainer 22 is pinned to the top connection 16 by means of
shear screws 20. Below retainer 22 and threadedly engaged therewith
is a mandrel slip housing 24 having a cone-shaped inner wall
26.
An annular chamber is formed by the wall 26 and the outer surface
of the mandrel 10. In this chamber is a split ring retainer wedge
28. Wedge 28 may slide downward along mandrel 10 freely but will
oppose movement upward. Each segment of wedge 28 is spring biased
downward by springs 32 which engage wedge 28. Springs 32 bias wedge
28 and are positioned on guide pins which are press fitted into a
mandrel slip ring 36.
As shown in FIG. 5, the mandrel 10 is cylindrical as is the housing
24. However, wedge 28 is made up of arcuate segments mounted in the
annulus between mandrel 10 and housing 24. Each segment of wedge 28
extends over an angle of almost 90.degree., leaving relatively
small slots 29 between the confronting edges.
As best shown in FIG. 6, wedge 28 is internally grooved or threaded
presenting sharp upfacing edges to engage mandrel 10. Each element
of wedge 28 has a slot 30 in the upper surface thereof to receive a
spring such as spring 32.
Immediately below the housing 24 is a bidirectional grip 38 which
encircles mandrel 10. A first set of teeth 40 is located on an
upper shoulder of grip 38. A second set of teeth 42 is located on a
lower shoulder. Grip 38 is hollow having an axial bore 46 and an
offset bore 44. Bores 44 and 46 are of the same diameter and are
sized to accommodate mandrel 10. The bores are blended to permit
tilt or rotation of grip 38 about an axis perpendicular to the axis
of mandrel 10 and perpendicular to the plane which is common to the
axes of bores 44 and 46.
In the preferred form, grip 38 will have the configuration as
generally illustrated in FIG. 7. It will be noted that the axis 46a
of bore 46 is offset by an angle 46b, preferably of the order of
about 20.degree., from the axis of the bore 44. Bores 46 and 44 are
of sufficient diameter for free movement of grip 38 from one
extreme to the other as limited by the offset between bores 44 and
46.
The sets of teeth 40 and 42 each comprises eleven courses numbered
1-11, FIG. 7. The teeth are cut transverse to an axis which lies
between axes 44a and 46a.
Teeth 40 and 42 are each formed on a curved shoulder so that the
grip 38 will accommodate or be workable in casings having internal
diameters over some predetermined limited range. For example, in a
packer where the length 38b of a grip 38 was of the order of 7
inches, a grip constructed as shown in FIG. 7 was suitable for use
in casing of internal diameter from about 6.4 inches to about 6.1
inches. As the grip 38 pivots or tilts about its central axis 38m,
one of the teeth in set 40 and one of the teeth in set 42 will make
initial contact with the casing wall. The tooth, or teeth, which
engage the wall will do so with approximately the same angle above
the tooth as below the tooth relative to the casing wall. Adequate
force is applied so that the teeth actually penetrate to a degree
the casing wall so that several teeth generally are called into
play. They resist movement of grip 38 about equally in both the
upward and downward direction.
Both ends of grip 38 are of the same configuration. Sets of teeth
40 and 42 generally are on opposite sides of the grip 38.
Teeth 40 may be cut spirally on the upper end of grip 38 or as
parallel grooves. Grip 38 will tilt or pivot about the center line
38m in response to the couple represented by arrows 38p and 38q
applied as housing 24 and shoulder converge.
Grip 38 may be unset by application of a force represented by arrow
38r.
Grip 38 has a vertical upfacing slot 48 immediately above the teeth
42. A retaining spring 50 is secured in slot 48 by screw 51 to
maintain the grip 38 in the unset position illustrated in FIGS. 1
and 2.
A downwardly facing release slot 52 is provided immediately below
the teeth 40 and diametrically opposite slot 48.
A grip release lug 54, FIG. 2, extends up into the bottom of slot
52. The inner surface 56 of lug 54 is formed with the same radius
as the outside of mandrel 10. Release lug 54 has an intermediate
downward facing shoulder 60 in contact with the upper surface of a
lower head ring 62.
As best shown in FIG. 8, the slot 52 has a width approximately
one-third the diameter of the mandrel 10. The lug 54 normally rests
on the upper surface 63 of head ring 62. However as will later be
explained, lug 54 is driven upward so that the top 55 of lug 54
engages the upper end 53 of slot 52 to rotate or tilt grip 38 back
into an orientation such that the bore 46 is parallel to mandrel
10.
Head ring 62 threadedly engages an elongated spacer collar 64. A
longitudinal slot 66 extends lengthwise of collar 64 to a point
just above its lower threaded section 68.
A set screw 70 is threaded into a radial lug 72 formed on the outer
surface of the mandrel 10. The head of screw 70 is positioned in
longitudinal slot 66 to prevent rotation of the mandrel after the
packer is set. Such rotation would be undesirable in any operation
requiring application of rotational forces to the top of mandrel
10.
The lower end 68 of collar 64 is coupled by threads to a second
mandrel slip housing 74. The configuration of housing 74 is similar
to housing 24. It has a cone-shaped inner wall 76 which forms an
annular space with the outer wall of the mandrel 10. Within this
annular space is a split ring wedge 77 arranged in a manner similar
to wedges 28, FIG. 2. Wedge 77 restricts upward movement of housing
74 with respect to the mandrel 10.
In FIG. 3 only two of the elements of wedge 77 are shown. The
elements of wedge 77 are biased by means of springs 78 with the
springs guided on pins inserted into a slip ring 82.
A packer unit 84 encircles mandrel 10 immediately below housing 74.
Packer unit 84 in this embodiment comprises two end rings 86 and 88
and a center ring 90. Rings 86, 88 and 90 are made of an elastomer
such as rubber, synthetic rubber or other material compatible with
the environment. The opposite ends of rings 86 and 88,
respectively, are provided with flanged metal stiffening rings 92.
The center ring 90 has tapered upper and lower ends that mate with
reverse tapers of the confronting ends of rings 86 and 88.
A thimble 94 concentric with the mandrel 10 supports the bottom of
ring 88. Threaded onto the bottom of thimble 94 is a dog housing 96
having a longitudinal slot 98 extending from thimble 94 to a point
about half way down the length of the housing 92.
The head of a lock screw 100 extends into slot 98. Screw 100 is
supported by a lock body 102 which is threaded onto the lower end
14 of the mandrel 10. Housing 96 is concentric with lock body 102
with sliding clearance therebetween. Screw 100 in slot 98 prevents
rotation between the housing 96 and lock body 102.
FIG. 9 is a longitudinal sectional view of lock body 102. A
plurality of circumferentially spaced windows 104 are located near
the lower end thereof. Body 102 is formed with a cylindrical
re-entrance passage therethrough with the windows 104 being in the
lower large diameter portion. The upper end is internally threaded
to receive the lower end 14 of mandrel 10. In the form illustrated
in FIG. 9, four windows 104 are shown, there being six windows
total in body 102. In the bars between windows 104 are threaded
holes 105 which receive shear screws 107.
Referring again to FIG. 4, each window 104 will contain a locking
dog 106. In this embodiment, six locking dogs are employed. Each
locking dog 106 has a partially beveled upper surface. The outer
curved surface of dog 106 mates with the inner surface of dog
housing 96. The inner surface of dog 106 is curved to mate with the
outer surface of a dog retainer 108. Each locking dog 106 is
provided with its upper outer beveled edge to mate with the bottom
beveled edge of a dog housing insert ring 110. The beveled surfaces
cooperate as will later be explained in order to retrieve the
packer.
Dog retainer 108, FIG. 4, includes central outward facing groove
112. Groove 112 faces the inner wall of a guide body 114. Dog
retainer 108 is supported on a shoulder 116 of the guide body 114.
At the lower end of retainer 108 is an inward facing groove 118.
Groove 118 has upper and lower beveled ends. A lip 120 is located
at the bottom of retainer 108 for use in retrieving the packer.
FIG. 10 is a longitudinal sectional view of the lower portion of
body 114. FIG. 11 is a transverse sectional view of the lower end
of body 114. Four circumferentially spaced guide fingers 122 in the
form of longitudinal interior ribs are shown in FIGS. 4, 10 and 11
as being integral with the lower end of body 114. The inner
surfaces of fingers 122 are curved on a diameter slightly smaller
than the inner diameter of the lip 120, FIG. 4. Between adjacent
guide fingers 122 is a slot 123, the diameter of which is equal to
the inner diameter of the lip 120.
In FIG. 10, the longitudinal sectional view of the lower ends of
retainer 108 and guide body 114 are rotated 45.degree. from the
section of FIG. 4. This shows lip 120 overlapping the top of the
slots 123 between fingers 122. Lip 120 is undercut to provide a
downward facing upward and outward sloping shoulder 124. In FIG. 11
fingers 122 alternate with grooves 123. The lip 120, FIGS. 4 and
10, overlaps grooves 123 because it is of diameter equal the
diameter of the inner surfaces of the fingers 122.
As shown in FIG. 12, the dog housing 96 encircles lock body 102
inside of which is located the dog retainer 108. Shear screws 107
secure dog retainer 108 to lock body 102.
SETTING THE PACKER -- WIRE LINE
The packer illustrated in FIGS. 1-11 may be set mechanically,
hydraulically or by wire line.
The structure shown in FIGS. 1-12, and particularly the top
connection 16 as mounted in this system is particularly adaptable
for wire line setting. More particularly, a wire line pressure
setting assembly (not shown) is fitted onto the top connection 16
by way of an adapter (not shown). The packer is then lowered into
the borehole to the desired depth on a wire line and there
actuated.
Such setting assemblies in general are well known. A suitable
setting assembly is the Baker Wire Line Pressure Setting Assembly,
Product No. 437-02 manufactured and sold by Baker Oil Tools of Los
Angeles, Calif. With such assembly, there will be employed the
well-known Guiberson B-Adapter Kit manufactured and sold by
Guiberson of Dallas. Tex. Such kit would include a 35,000 lb. shear
ring. Such units have long been used in oil well operations.
The pressure setting assembly and the Adapter Kit above identified
serve to apply an upward force in the direction of arrow 200, FIG.
2, to the top connection 16 and at the same time by way of a sleeve
(not shown but which extends down over top connection 16 as a part
of the adapter kit) to apply a downward force as represented by
arrow 202 to the top of the mandrel slip retainer 22.
By way of brief explanation, such pressure setting assemblies are
adapted to be actuated by an electrical signal on the supporting
wire line which leads from the surface. Such signal detonates a
suitable explosive or combustible material to produce gas pressure
in a piston chamber. The chamber and piston are connected as to
apply the upward force 200 and the downward force 202. Such forces
cause screws 20 to shear. Once screws 20 are severed, mandrel 10
tends to move upward while retainer 22 and housing 24 tend to move
downward. The lower end of housing 24 engages the upper end of grip
38 at a point adjacent to the top of threads 40. Since mandrel 10
is connected to lock body 102 and, by way of dogs 106 to dog
housing 96, upward movement of mandrel 10 results in application of
a force represented by arrow 38q, FIG. 7. This force is transmitted
from dog housing 96 by way of thimble 94, bottom packer ring 88,
packer ring 90, packer ring 86, mandrel slip housing 74, collar 64
and lower head 62. The lower head 62 bears against the bottom of
the grip 38 adjacent threads 42. As housing 24 and the lower head
62 move toward each other, grip 38 is rotated, overcoming the force
of spring 50 so that the teeth in both sets 40 and 42 engage the
casing wall on opposite sides of the casing and at opposite ends of
grip 38.
As motion in the direction of arrows 200 and 202 continues, the
casing will oppose significant further rotation of the grip 38.
However, continued motion of mandrel 10 upward relative to housing
24 causes packer unit 84 to bulge outward into sealing contact with
the wall of the casing. As the casing further limits distortion in
the rubber elements, progressively increasing force is applied to
the grip 38 to partially embed the teeth in the walls of the
casing.
Distortion of the rubber elements continues until the pressure in
the pressure setting assembly reaches a predetermined level. As
above indicated, a shear ring employed in the Adapter Kit controls
this level. In the example given, a 35,000 pound shear ring was
specified. In such case when the pressure in the pressure setting
assembly reaches 35,000 p.s.i. thus determining the magnitude of
forces 200 and 202, the shear ring in the adapter kit fails,
releasing the pressure setting assembly and the adapter kit from
the top connection 16. The pressure setting assembly and the
adapter kit may then be withdrawn from the well.
Upon release of the pressure setting assembly and adapter kit, the
mandrel 10 tends to move downward relative to housing 24. Such
movement is immediately arrested by the wedges 28 and 77. Wedge 77
separately locks packer unit 84 in the set configuration in order
to avoid any release of the packer unit 84 as might otherwise occur
if the downhole pressure on the packer exceeded the setting
pressure (35,000 pounds in the example) and were then released.
Such excess pressure would pivot grip 38 to a greater angle.
Removal of such excess pressure would then release to some degree
packer unit 84 in the absence of wedge 77.
With the wire line removed, the operator is then free to conduct
such tests as may be appropriate or other operations desired in
connection with the packer set at the desired depth.
SETTING THE PACKER -- HYDRAULICALLY
The packer may be set hydraulically by use of the adapter unit
shown in FIG. 15. In this embodiment, the mandrel 10 is secured by
threads 300 into the bottom of an adapter collar 301 which has
threads 302 in the upper end thereof for coupling collar 301 to
tubing (not shown). A cylinder 304 encompasses the collar 301.
O-rings 306 in grooves on the outer surface and near the lower end
of collar 301 provide a pressure seal between the outside of the
collar 301 and the inner wall of the cylinder 304. The bore in
cylinder 304 is reentrant with the smaller diameter portion 308
fitting closely around the outside of mandrel 10. O-rings 310 in
grooves on the inner wall of the small diameter portion 308 provide
a pressure seal between mandrel 10 and portion 308. Mandrel slip
housing 24, shown in detail in FIG. 2, threadedly engages the
bottom of portion 308.
Ports 312 extend laterally through the wall of mandrel 10 adjacent
the bottom of threads 300.
Shear screws 314 extend through the upper end of cylinder 304 into
a groove 316 in the region of threads 302 on collar 301.
In setting the tool hydraulically, the lower end of the packer is
provided with an expandable or relievable valve generally in the
manner described in connection with FIG. 16c of U.S. Pat. No.
3,548,936.
With the lower end of the mandrel 10 closed by such valve means,
pressure applied through the tubing connected at threads 302 will
be exerted through ports 312. As the pressure builds up, shear
screws 314 part permitting the surfaces 318 to part, thus causing
mandrel 10 to move upward and housing 24 to move downward. By this
means the packer will be set with the wedges 28 and 77 providing
restraint in the set configuration when the pressure in the tubing
is relieved. The tubing and the valve at the lower end of the
mandrel may then be removed in a conventional manner for use of the
packer.
SETTING THE PACKER -- MECHANICALLY
The packer may be set mechanically by use of the adapter shown in
FIG. 16. In this embodiment, an adapter 320 is secured to mandrel
10 by the threaded section 322. Adapter 320 has threads 324 in the
upper end thereof for coupling to tubing to be used in the setting
operation. An anti-rotation sleeve 326 is connected to adapter 320
by a limited threaded section 328. More particularly, a short
length of the outer surface of adapter 320 is provided with
external threads which mate with internal threads about midway the
length of sleeve 326. The exterior of sleeve 326 has a plurality of
longitudinal grooves 330 extending from near the bottom to the top
thereof. Bow springs 332 are mounted in grooves 330 by means of
screws 334. Screws 334 are located near the bottom of sleeve 326.
The upper portion of the bore of sleeve 326 is slightly larger in
diameter than the crown of the threads 328 on the adapter 320 so
that sleeve 326 may pass freely down over thread section 328 when
the threads are disengaged. The bore in sleeve 326 is reentrant
having a smaller diameter portion 336 at the lower end which is
provided with threads to which the upper end of housing 24 is
secured.
In operation the packer is lowered into the borehole on the end of
tubing (not shown) coupled to threads 324. When at desired depth,
the tubing is rotated to disengage threads 328 on adapter 320 from
mating threads on sleeve 326. The tendency of sleeve 326 to rotate
with adapter 320 is opposed by the frictional engagement of the bow
springs 332 with the wall of the casing.
When threads 328 become disengaged, upward movement of the tubing
carrying adapter 320 and mandrel 10 with it will take place
relative to sleeve 326. Springs 332 oppose upward movement of
sleeve 326 to the extent that the force of spring 50, FIG. 2, is
overcome, tilting grip 38 into engagement with the casing wall.
Further upward force supplied to the tubing will then embed the
grip 38 in the casing and seal packer unit 84 against the casing
wall.
RETRIEVING THE SET PACKER
After the packer has been set and the desired operations have been
conducted in the well, it is often desired to release the packer
and retrieve it from the well.
The packer shown in FIGS. 1-11 may be retrieved by applying an
upward force on grip 38 as represented by arrow 38r, FIG. 7, by use
of a packer retriever 210, FIG. 13.
Packer retriever 210 is shown in FIG. 13 in position preparatory to
being latched onto the packer and is secured to the lower end of
tubing 214.
Retriever 210 includes an upper collar 216 which is threaded at the
upper end to engage tubing 214. Collar 216 is internally threaded
at its lower end to receive a retriever mandrel 218. Retriever
mandrel 218 has a first set of threads 220 at the upper end thereof
which are served into the lower end of the collar 216. A second set
of threads 222 are positioned below threads 220 and are of larger
diameter than threads 220. A slotted sleeve 224 is telescoped
downward over retriever mandrel 218. The upper end of the sleeve
224 is internally threaded on an internal shoulder to be served
onto thread 222. Thus, there is an annulus between mandrel 218 and
sleeve 224. Sleeve 224 extends downward onto shoulder 226. A screw
228 is employed to lock the sleeve 224 and prevent rotation
relative to mandrel 218.
Sleeve 224 has four longitudinal slots such as the slot 230. The
slots extend substantially the entire length of the sleeve 224 with
ribs therebetween. Ribs 234, 242 and 246 are shown in FIG. 13. A
central transverse guide lug 232 is formed on the outer surface of
the rib 234. A hook 236 is formed on rib 234 below lug 232. Hook
236 is upwardly and outwardly beveled. The upper and lower surfaces
of lug 232 are beveled towards the rib 234.
FIG. 14 illustrates the relationship between retrieving mandrel 218
and sleeve 224. Rib 234 occupies about one-eighth of the
circumference of sleeve 224. As viewed in FIG. 14, the upper
surface of the lug 232 extends radially outward from rib 234. In a
similar manner, ribs 240, 242 and 246 form parts of the sleeve 224.
Ribs 234, 240, 242 and 246 are centered at 90.degree. intervals
about sleeve 224. Slot 230 extends substantially the length of the
sleeve 224 between ribs 242 and 246. Similarly, slots 248, 250 and
252 are located between the remaining ribs.
The outer diameter of lugs 232 and hooks 236 is greater than the
inner diameter of lip 120, FIG. 4. It will be appreciated that ribs
234, 240, 242 and 246 will flex inwardly under the weight of the
tubing 214 to be forced downward through the dog retainer 108 and
through the lower end of the guide body 114.
To release the packer, the tubing 214, FIG. 13, is drawn upward. If
lugs 232 and the hooks 236 are in angular positions such that as
they move upward they register with the slots 123, FIGS. 10 and 11,
then lug 232 will snap outward into the groove 118 and the hook 236
will engage lip 120.
Referring to FIG. 4, the application of a force to lip 120 will
shear screws 107, releasing retainer 108 from its position at the
bottom of lock body 102. Upward movement upward of the entire
packer, however, is foreclosed by the fact that the grip 38 is set
in the casing. Thus, when retainer 108 is freed by shearing screws
107, it may move upward freely until the shoulder at the bottom of
groove 112 engages the lower end 101 of lock body 102. Further
upward movement tends to raise dogs 106 upward. As a result, dogs
106 are forced inward into the groove 112 by the cooperation
between the upper grooved edge of the dogs 106 and a downward
beveled edge of the ring 110. Dogs 106 move inward a distance
sufficient for the outer surface of the dogs to clear the inner
wall of the dog housing 96. In such position, mandrel 10, lock body
102, dog retainer 108 and dogs 106 may then move upward relative to
housing 96. Further upward movement permits the shoulder on lug 72
to move upward into engagement with the lower end of the grip
release lug 54. As lug 54 then moves upward, the upper end thereof
travels to the end of slot 52 and engages the grip 38 to rotate it
counterclockwise and thereby release it from the set position. When
this is done, the packer elements are free to resume their unset
configuration and the packer may be retrieved or withdrawn from the
hole supported on the tubing.
The construction of the retriever 210 and the ribs and grooves in
body 114 provides for selective retrieval. FIG. 14 shows that the
lugs such as lug 232 occupies about one-eighth of the circumference
of the sleeve 224. From FIGS. 4, 10, 11 and 12 it will be apparent
that the ribs 122 occupy substantial portions of the circumference
of the guide body 114, each less than one-eighth thereof. The
dimensions are such that with random orientation, hook 236 will, on
the average, engage lip 120 about one out of every four times the
retriever 210 is drawn upward through the lower end of the packer
assembly.
Thus, in retrieving the packer, the procedure is to lower the
retriever 210 until hook 236 passes below the edge of lip 120.
Thereafter, the tubing 214 is raised. Increase in weight on the
tubing, as conventionally measured at the drilling floor, will
reveal to the operator whether or not lip 120 has been engaged by
hook 236. If there is no buildup of weight as the hook 236 passes
the location of lip 120 and retrieval is desired, then the tubing
string is rotated, lowered and again raised. The procedure is
repeated until a weight indicator signals the fact that the packer
has been engaged. Thereafter, such force is applied through the
tubing as to shear screws 107. The packer may then be withdrawn
from the borehole and the shear pins again installed to place the
packer in condition for another cycle of use.
It may be that the tubing and retrieving tool are to be removed
without releasing the packer. This may be done when desired. More
particularly, if the weight on the tubing when raised indicates the
retriever 210 is hooked in the packer, the tubing may be lowered,
rotated and again raised. Three out of four times, the retriever
will not hook the packer, thus permitting selective retrieval
operations.
The packer and retrieving system above described has significant
capability in that the same structure may be set in the well by all
three of the methods, i.e., wire line, hydraulic and mechanical. In
addition, the packer is selectively retrievable regardless of which
method of setting is utilized.
Further, a single grip serves to resist substantially equal forces
from both uphole and downhole. Further, the packer is selectively
retrievable by reason of the geometric relationship between the
ribs 122 and recesses 123, FIG. 11, and the hooks 236, FIG. 14.
Selective retrievability is an attribute that is important in well
operations.
The foregoing description has been specific as to a single
embodiment of the invention. It will be understood that
modifications may be made, departing from the specific structure
here shown while embodying the invention. More particularly, while
six dogs 106 are shown in FIG. 12 and six windows are provided in
insert cylinder 102, different numbers and different sizes of dogs
may be employed. Dogs 106 preferably are made of specially hardened
steel to avoid deformation due to the high forces supplied thereto
during the setting operation. In addition, the ring 110 is of
similar hardened steel material so that when the dogs 106 are to be
forced into recess 112, a distance sufficient for the dogs to clear
the inner wall of the drive cylinder, the transfer can be
accomplished without distorting the shape of the dogs 106 or the
ring 110.
While the packer element 84 has been illustrated and described as
comprising the three rings 86, 88, and 90, it will be appreciated
that a single resilient ring or band of unitary character may be
employed in place of the three rings 86, 88 and 90 for distortion
upon axial compression into sealing contact with the casing
wall.
Further, the teeth 40 and 42 formed on grip 38 are on curved
shoulders in the zones adjacent to the opposite extremities of the
beveled ends of the grip 38. The sets of threads are located at
diametrically opposed zones on the grip. The teeth are shaped as to
resist movement relative to the casing once this grip 38 engages
the casing, preferably engaging the casing about equilaterally,
i.e., the angle between the tooth surface and casing wall above a
tooth is about equal to the corresponding angle below the
tooth.
In one aspect the packer comprises the cylindrical mandrel 10
encircled by resilient packer unit 86, 88 and 90 which is radially
deformable into casing contact when longitudinally compressed.
Drive cylinder 96 secured to mandrel 10 below packer unit 86, 88,
90 supports the packer unit. Spacer 64 encircles the mandrel and
bears against the top of the packer unit while movable
longitudinally on the mandrel. Grip 38 responds to the couple 38q,
38p, FIG. 7, between spacer 64 and upper cylinder 22, 24 to tilt
into engagement with the casing although normally resiliently
biased toward an untilted attitude. The couple is produced by
forces acting upward on mandrel 10 and downward on cylinder 22, 24
to set grip 38. This force is transmitted through packer unit 86,
88, 90 to tilt and wedge grip 38 between opposite sides of the
casing as the packer unit seals the annulus between mandrel 10 and
the casing. Wedge retainer 28 between cylinder 22, 24 and mandrel
10 permits downward movement and prevent upward movement of
cylinder 22, 24 with respect to mandrel 10.
Once set, grip release bar 54, supported by spacer 64, extends into
the mouth of slot 52. Lug ring 72 on the surface of mandrel 10
serves to drive bar 54. The releasable coupling between mandrel 10
and drive cylinder 96, when actuated, permits upward movement of
mandrel 10 relative to cylinder 96 whereupon mandrel 10 may drive
bar 54 by lug ring 72 against the end of slot 52.
Movable captured shear resistant dogs 106 nested in recesses in the
bottom of the packer span a boundary common to mandrel 10 and drive
cylinder 96. Insert cylinder 108 is supported by mandrel 10.
Cylinder 108 has outward facing peripheral groove 112 dimensioned
to accommodate dogs 106 and normally to restrain them so long as
groove 112 is positioned below dogs 106 and maintain the capture
thereof. Structure 114 supports insert cylinder 108 from drive
cylinder 96. Vertical internal ribs 122 in structure 114 are
circumferentially arrayed below cylinder 108 and are of internal
diameter about the same as the internal diameter of insert cylinder
108 and are separated by vertical recesses 124.
Tubing controlled hooks 236, FIG. 13, are insertable down through
mandrel 10. Hooks 236 may engage the bottom of insert cylinder 108
only when aligned with recesses 123 to move groove 112 of cylinder
108 into registration with dogs 106 thereby to release mandrel 10
from drive cylinder 96.
Having described the invention in connection with certain specific
embodiments thereof, it is to be understood that further
modifications may now suggest themselves to those skilled in the
art and it is intended to cover such modifications as fall within
the scope of the appended claims.
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