Note: Descriptions are shown in the official language in which they were submitted.
~9~5b~
1. Field of the Invention
The present invention is particularly adaptea for use in
high tempPrature wells where ste,~m is injected into an under-
ground formation to enhance the recovery of hydrocarbons. The
present invention can also be used in high pressure/high tem-
perature geothermal wells.
2- e~_9~35~ ~L~æ~ LæL_~5
Yor many years packers have been used to prov:ide a seal
between a tubing string and a casing -~tring within a well
k,ore. Generally, formation fluids enter the bore of the
casing string below the packer and are directed to flow to the
well surface through the tubing string by the packer;. Thus,
the casing above the packer is protected from the formation
fluids. Also, the well is easier to contrc,l by confin:ing the
formation fluids to the tubing string.
... .
~ . . .
The usa of packers and tubing is even more important
while injecting high temperatura and pressure steam into a
hydrocarbon formation or in recovering energy from deep geo-
thermal wells. U.S. Patents 3 f 330,357 and 3~385,366 to T. L.
Elliston show packers using asbestos rings to form a seal
under high temp~rature conditions. U.S. Patent ~,050,517
discloses flexible seals to compensate for the high tempera-
tures found in geothermal wells.
Canadian Patent No. 1,102,6~0 issued to Joseph L.
Pearce et al discloses using elastomeric material reinforced
with wire mesh in pumpdown piston elements. The reinforced
elastomeric material displays markedly improved wear character-
istics while the pumpdown element is moving through a well
conduit. Various patents cited in this application, :includ-
ing U.S. Patent 2,143,106 to A. L. Freedlander, disclose
' reinforcing alastomeric material with metal for use in oil
and gas wells.
None of these patents show nor teach a packer having a
sealing unit or anchoring means in accordance with the
present invention.
Summary of the Invention
The present invention discloses a packer for forming a
seal with the inner wall of a casing string comprising:
means for connecting the packer to a tubing string; mandrel
means having a longitudinal flow passage to provide fluid
communication through the packer; means for anchoring the
packer to the inner wall of the casing string intermediate
the ends of the casing string; the anchoring means further
comprising: housing means mounted on the exterior of the
mandrel means; openings in the housing means; slip means
disposed within said openings, having a first position
retracted within the housing means and a second position
partially extended from the mandrel means through the
7~
openings; a first slip expander ring and a second slip ex
pander ring slidably carried vn the exterior of the mandrel
means at opposite ends of ~he housing means; camrning sur-
faces on each expander ring for engaging the slip means to
project the slip means through the openings; means for
moving the first expander ring towards the second expander
ring to project the slip means; means Eor releasing the
packer from the inner wall of the casing string; a sealiny
unit, attachea to the exterior of the mandrel means, having
a first position in which the sealing unit is relaxed and a
second position in which the sealing unit is longitudinally
compressed and radially expanded to contact the inner wall;
the means for releasing the packer further comprisin~: the
camming surface on the second ring formed on inwardly
flexible collet Eingers; a collet support ring slidably
disposed between the collet fingers and the mandrel means;
the collet support ring preventing the collet fingers from
flexing inwardly; the collet support ring being releasably
secured to the collet finger~; and means carried on the
exterior of the mandrel means, for engaging the collet
support ring and releasing the collet fingers after the
mandrel means has moved longitudinally a preselected dis-
tance relative to the second expander ring ,allowing the
second expander ring to disengage from the 51ip means~
The invention also discloses a packer for forming a
seal with the inner wall of a casing string, comprising:
means for connecting the packer to a tubing string disposed
within the casing string; mandrel means having a longitud-
inal flow passage to provide fluid communication through the
packer; a sealing unit attached to the exterior of the
mandrel means; the sealing unit comprising an upper support
ring and a lower support ring with backup rings and elasto-
meric material disposed between the support rings; the
-2a-
sealing unit having a first position in which the support
rinys are releasably secured at fixed locations on the
mandrel means and spaced lonyitudinally from each other with
the elastomeric material relaxed; the sealing unit having a
second position in which the upper support ring is released
from its fixed location on the mandrel means and the lower
support ring has been moved towards the upper support ring by
tha mandrel means compressing the elastomeric material there-
between; the sealing unit having a third position in which
both the upper and lower support rings are released from their
fixed positions on the mandrel means and the sealing unit can
slide over the exterior of the mandrel means with the elasto~
meric material relaxed; means for anchoring the packer to ~he
inner wall of the casing string and moving the lower support
ring towarcls the upper support ring placing the sealing unit
in its second position; means for releasing the packer from
the inner wall and moving the sealing unit to its third
position; the anchoring means further comprising a cylindrical
housing slidably mounted on the exterior of the mandrel m0ans;
a plurality of radial openings in the housing; slips, disposed
within the openings, having a first position retracted within
: the housing and a second position partially extended through
the openings; an upper slip expander ring and a lower slip
expander ring slidably carried on the exterior of the mandrel
means near opposite ends of the housing; camming surfaces on
each expander ring for engaginy a matching surface on the
slips; the lower expander ring abutting the upper support ring
of the sealiny unit; means for moving the upper expander ring
towards the lower expander ring thereby projecting the slips
through the openings; the force required to release the upper
support ring from the mandrel means being preselectecl to allow
the slips to engage the inner wall before the upper support
ring is released from the mandrel means; and the means for
-2b-
..
moving the upper expander ring applying force to the mandrel
me~ns to move the sealing unit to its second position after
the slips have engaged the inner wall.
The invention further discloses a packer for forming a
seal with the inner wall o~ a casing string comprising:
means for connecting the packer to a tubing string; mandrel
means having a longitudinal flow passage to provide fluid
communication through the packer; means for anchoring the
packer to the inner wall of the casing string intermediate
the ends of the casing string; means for releasing the
packer from the inner wall of the casing string; a sealing
unit, attached to the exterior of the mandrel means, having
a first position in which the sealing unit is relaxes and a
second position in which the sealing unit is longitudinally
compressed and radially expanded to c~ontact the inner wall;
the mandrel means movable longitudinally in one direction
;~ with respect to the anchoring means to move the sealing unit
to its second position after the packer has been anchored to
the inner wall; internal slips carried within the packer and
engageable with the exterior of the mandrel means; teeth on
the internal slips allowing movement of the mandrel means in
the one direction and preventing movement in the other
direction; and the exterior of the mandrel means having a
rough surface designed to match the teeth on the internal
, slips.
',"'t~ 2c-
One object of the present invention is to provide a
well packer having a sealing unit w.ith ~lastomeric mater.ial
reinforced by wire mesh~
Another object of the present invention is to provide a
.~ well packer which can form a seal between casing and tubing
while subjected to high pressure and temperature.
A further object of the present invention is to provide a
well packer having a single set of slips which can withstand
differential pressure in either directiorl.
10Still another object of the present invention is to
provide a sealing unit having an array of packing elements
comprising a center element, a plurality of end elements
disposed on either side of the center element, and one or more
concaved reinforcing discs at each end of the array.
Another object of the present invention is to provide a
packer which can be either hydraulically or mechanically set
and released by upward tensJ.on on the tubing string.
A still furthex object of the present invention is to
; provide a packer having a sealing unit with the geometric
shape of the packiny elements allowing selective, longitudinal
compression of the center element and end elements.
Additional objects and advantages of the present inven-
tion will be readily apparent from reading the detailed de-
scription in conjunction with the drawings,
Brief Description of the Drawings
FIGURES lA, B, and C are drawings, partially in section
and partially in elevation, showing a hydraulic set packer of
the present invention with the anchoring means and sealing
unit in their first position as the packer is lowered into a
casing string.
; FIGURES 2A, 2B, and 2C, partially in section and par-
tially in elevation, show the hydraulic set packer with the
anchoring means and the sealing unit in their second position
forming a seal with the inner wall of the casing string.
; FIGURES 3A, 3B and 3C/ partially in section and partially
in elevation, show the hydraulic set packer with the sealing
unit in its third position as the packer is removed from a
casing string.
FIGURE 4 is a cross section taken along line 4-4 of
FIGURE lA.
FIGURE 5 is a cross section taken along line 5-5 of
FIGURE lB showing the slip means in more detail.
- FIGURF. 6 is a cross section taken along line 6-6 of
FIGURE lB showing the colle~ fin~ers and camming sur~aces of
the lower or second expander ring and the collet support ring.
FIGURES 7, 8, 9, 10, 11 and 12 are schematic drawings,
partially in section r showing various arrays of center ele-
ments, end elements, and backup rings or reinforcing discs
which can be used on the sealing unit of the present
invention.
FIGURE 13 is an enlarged sectional view of the second or
lower expander ring.
FIGURE 14 is a cross section taken along line 14-14 of
FIGURE 13.
FIGURE 15 is a cross section taken along line 15~15 of
FIGURE 13.
FIGURES 16A, B and C are drawings, partially in section
and partially in elevation, showing a mechanisally set packer
i of the present invention with the anchoring means and the
sealing unit each in their first position.
Descriptlon of the Preferred Embodiment
Referring to the draw.ings and par~icularly FIGURE lA, lB
and lC, well packer 20 is attached to tubing s-tring 21.
FIGURES lA, lB and lC show packer 20 with sealing unit 30 and
slip means 50 each in their respective first position. This
is the normal condition in which packer 20 would appear prior
to being installed in a well and while being lowered by tubing
string 21 through the bore of a casing st:ring.
: Packer 20 comprises a mandrel means 22 which has a longi-
tudinal flow passage 23 therethrough. Longitudinal passage 23
is concentric with the bore of tubing 21 and communicates
fluid from below packer 20 to tubing 21. Mandrel means 22
includes an adapter sub 22a which has threads 24 formecl on one
end to provide a means for connecting packer 20 to tu~ing
string 21~ Various well tools or additional tubing could be
attached to mandrel mean~ 22 at its lower end 22b.
The major components of packer 20 are generally cylin-
drical and carried on the exterior of mandrel means 22. Means
for anchoring packer 20 to the inner wall of a casing string
includes piston housing 41 which is engaged by threads 42 to
the exterior of adapter sub 22aO Lateral ports 43 and longi-
tudinal ports 44 formed in adapter sub 22a communicate fluid
from longitudinal flow passage 23 to the interior of piston
housing 41. Plugs 45 are threadedly engaged from the exterior
of adapter sub 22a into lateral ports 43. Plugs 45 provide
means for flushing ports 43 and 44 when packer 20 is at the
well surfaceO When plugs 45 are installed, they prevent fluid
within longitudinal passage 23 from escaping to the exterior
of packer 20.
Piston 46 is slidably disposed between piston housing 41
and the exterior of mandrel means 22. Piston seals 47,
carried on the end of piston 46, form a slidable 1uid
barrier. Variable volume fluid chamber 48 i5 partially
defined by the exterior of mandrel means 22, the inside
diameter of piston housing 41, and piston seals 47. Fluid
pressure within longitudinal flow passage 23 can be communi-
cated by ports 43 and 44 to variable volume chamber 48 to move
piston 46 longitudinally with respect to mandrel means 22. As
will be explained later, -this movement of piston 46 causes
slip means 50 to extend radially from mandrel means 22 anchor-
ing packer 20 to the inner wall of casing 25. Since piston
housing 41 is engaged by thxeads 42 to adapter sub 22a, the
location of piston housing 41 relative to mandrel means 22
remains fixed while running, setting, and pulling packer 20.
The end of piston 46 opposite piston seals 47 ls ~ngaged
by screws 51 to upper or first expander ring 52. Shoulder 49,
formed on piston 46, abuts first expander ring 52. Slip means
50 is expanded radially by moving first expander ring 52 and
second ox lower expander ring 53 longitudinally towards each
other. Each expander ring is generally cylindrical and
carried vn the exterior of mandrel means 22. Four lugs 54 are
threaded into holes in the outside diameter of first expander
ring 52. Guide lugs 54 on first expander ring 52 are spaced
radially 90 from each other. Two lugs 54, spaced raclially
180 from each other, are threadedly attached to the exterior
of second expander ring 53.
Housing means 55 is generally a cylinder surrounding
mandrel means 22. Expander rings 52 ancl 53 are partially
disposed within the ends of housing 55 between the exterior of
mandrel means 22 and the inside of housing means 55 Longi-
tudinal guide slots 56 are cut in housing 55 near both ends
thereof. Guide lugs 54 are slidably disposed within slots 56.
Lugs 54 and slots 56 provide a means for interconnecting
housing 55 and expander rings 52 and 53 and still allowinglimited movement relative to each other.
Each expander ring has a tapered camming surface 57 on
the end adjacent to slip means 50. Frusto-conical s~rfaces 58
are formed on the inside diameter of slip means 50 near either
end thereof. Camming surfaces 57 and frusto-conical surfaces
58 are generally matching. Therefore, movement of expander
rings 52 and 53 towards each other causes camming surfaces 57
to act as wedges projecting slip means 50 radially from man-
drel means 22.
-~ Lower expander ring 53 is best shown in FIGURES 13, 14
- and 15. Camming surface 57 is formed on the exterior of
collet fingers 59. The six collet fingers 59 can 1ex in-
wardly. Threaded holes 60 are machined in two opposing collet
fingers 59 for lugs 54 to be secured therein. Collet support
xing 60 is shown secured by releasable means to the inside
diameter of collet Eingers 59. The releasable means comprises
three shear pins 61 spaced radially 120 connecting collet
support ring 60 to three of the collet fingers 59. A large
recess 62 is machined in the inside diameter of second ex-
pander ring 53 to facilitate inward flexing of collet fingers
59.
First expander ring 52 has an enlarged inside diameter 63
opposite a portion of its camming surface 57. Shoulder 64 is
formed by enlarged inside diameter 63. As will be explained
later, shoulder 64 and collet support ring 60 comprise a
portion of the means for releasing packer 20 from the inner
wall of casin~ string 25.
Sealing unit 30 is carri~d on the exterior of mandrel
means 22 longitudinally adjacent to second expander ring 53.
; Sealing unit 30 comprises a first or upp~r support ring 31
which is releasably secured to mandrel 22 by shear screws 32.
--7--
.
A second or lower support ring 34 is releasably secured to the
exterior of mandrel 2~ and spaced longitudinally from first
support ring 31. Shear screws 35 releasably secure support
ring 34 to mandrel means 22. The fir~t posltion of sealing
unit 30 in which it is relaxed i5 defined by shear screws 32
and 35 securing ~heir respective support ring to mandrel 22.
Various arrays of packing elements can be carried on the
exterior of mandrel 22 between support rings 31 and 34. ~he
array shown in FIGURE lB comprises metal backup rings or discs
33a, 33b, 33c and 33d, end elements 36a, 36b, 36c and 36d and
center elements 37. As will be explained later, various
combinations of center and end elements have been fo~ma to
provide a fluid tight seal under high pressure and temperature
conditions. To provide for improved support of the packing
elements, each support ring has a concaved surface 38 facing a
similar convex surface 39 on the backup rings 33. Sealing
element 30 is shown in FIGURE lB in its first, relaxed posi-
tion.
Referring generally to FIGURES 2A, 2~ and 2C, packer 20
is shown anchored to the inner wall of casing 25 by slip means
50. Sealing unit 30 is shown in its second position forming a
Eluid tight seal between casing 25 and mandrel means 22
Thus, any fluid entering casing 25 below packer 20 is directed
by sealing unit 30 to flow to the well surface through longi-
tudinal flow passage 23 and tubing string 21. In the same
manner, if a high temperakure fluid is injected ~rom the well
surface to an underground formation, sealing unit 30 prevents
the high temperature fluid from contacting the inner wall of
casing 25 above packer 20.
Setting tool 70 is shown disposed within the upper por-
tion of longitudinal flow passage 23. Fishing neck 71 is
provided on setting tool 70 so that tool 70 can be raised and
lowered by conventional wireline techniques through tubing 21.
Adapter sub 22a has a reduced inside diameter portion 72 which
forms a tapered shoulder ~or tool 70 to rest on. O-rings 76
are carried on the exterior of tool 70 and form a fluid tight
seal with the inside diameter of mandrel means 22 when tool 70
is resting on shoulder 72. A valve means consisting of valve
seat 73, valve disc 74 and valve stem 75 is con-~ained within
tool 70. Fishing ne~k 71 is attached to one end of ~alve stem
7S and valve disc 74 is attached to each other. Therefore,
when fishing neck 71 is pulled upward~ valve disc 74 is lifted
from valve seat 73 opening a fluid passage through setting
tool 70. The weight of valve stem 75 and disc 74 plus any
difference in fluid pressure above tool 70 as compared to
below tool 70 tends to clos~ the valve means. When tool 70 is
resting on tapered shoulder 72, O-rings 76, disc 74 and seat
73 cooperate to prevent fluid above tool 70 from flowing into
longitudinal flow passage 23 below tool 70.
Longitudinal slots 77 are machined in the circumference
of tool 70 from the end opposite O-rings 76. Slots 77 connect
with groove 78 machined in the outside diameter of tool 70
intermediate the ends thereof. Slots 77 and groove 78 are
sized to allow fluid within tubing 21 to communicate with
ports 43 and 44 when tool 70 is resting on shoulder 72. An
increase in fluid pressure within tubing 21 can thus be com-
munica-ted to variable volume fluid chamber 48~ The increased
fluid pressure causes piston 46 to move in one direction
relative to mandrel means 22.
Internal slips means 80 are disposed between the inside
diameter of first expander ring 52 and the exterior of mandre~
means 22. Internal slip means 80 consists of a ring 81 with a
longitudinal slot 82 formed therein. An enlarged wedge 83 is
formed on one end of ring 81. Spring 84 is disposed around
_9_
4~
the circumference of ring 81. One end of spring 84 rests on
the end of piston 46 and the other on wedge 83. Spring B4
biases internal slip means 80 in one direction away from
piston 46. Guide screw 85 i5 secured to the inside diameter
of first expander ring 52 and rides in slot 82 to prevent
rota-tion of slip means 8Q relative to expander ring 52. The
exterior of mandrel means 22 in the vicinity of internal slip
means 80 has a rough surface 86 which is designed to engage
matching teeth on the inside diameter of wedge 83. Internal
slip means 80 thus allows expander ring 52 to be moved in the
one direction by piston 46. When the fluid pressure in cham-
ber 48 is reduced, wedge 83 engages rough surface 86 and
prevents expander ring 52 rom moving in the other direction
relative to mandrel means 22.
As previously noted, sealing un.it 30 comprises an array
of packing elements carried between first support ring 31 and
second support ring 34. Shear screws 32 provide a means for
releasably securing support ring 31 to mandrel means 22.
Shear screws 35 provide a means for releasably securing sup-
port ring 34 to mandrel means 22~ Less force can be prese-
lected to release support ring 31 from mandrel means 22 as
compared to support ring 34 by installing fewer screws 32 than
screws 35. Alternatively, screws 32 can be selected from
material having a lower shear valve as compared to screws 35.
As best shown in FIGURES 2B and 2C, movement of piston 46
in one direction relative to mandrel means 22 causes the upper
and lower expander rings to move towards each other. Camming
surfaces 57 cooperate to radially extend slip means 50 from
mandrel means 22~ Serrated, diamond shaped teeth 90 are
formed on the outside diameter of slip means 50 and engage the
inside diameter of casing string 25. With the anchoring means
in its second position as shown in FIGURE 2B, packer 20
--10--
~-gr~
r~ists movement in either direction within the bore of casing
25.
After teeth 90 are set or engaged with casing 25, in-
creased fluid pressure within chamber 48 will cause mandrel
means 22 to continue in the one direction relative to i.nternal
slip means 80. This continued movement causes force to be
applied to upper support ring 31 which a:buts lower expander
ring 53. The pressure applied ~o variable volume chamber 48
is preselected to cause screws 32 to shear into two portions
32a and 32b as shown in FI&URE 2C~ Since screws 35 are pre-
selected to require more force before they will shear, the
continued movement of mandrel means 22 in the one direction
causes second support ring 34 to move towards first support
ring 31. The movement of the support rings towards each other
; causes longitudinal compression and radial expansion of the
packing elements.
As best shown in FIGURE 2C, seal.ing unit 30 forms a fluid
tight seal between mandrel means 22 and casing 25. Center
element 37 and end elements 36a, 36b, 36c and 36d are pre-
selected from materials found to be particularly suited ~or
use with high temperature fluid. One of ~he preferrecl com-
pounds for cenker element 37 is ethlene propylene-diene ter-
polymer, sometimes referred to as ~PD~. The end elements
preferably used with EPDM are made from vinylidene ~luoride
and/or hexafluoropropylene copolymer reinforced with wire
mesh. Vinylidene fluoride is sometimes referred to as VITON
and hexafluoropropylene is sometimes referred to as FLUOREL.
VITON is a registered trademark belonging to E.I. DuPont De
Nemours & CoO, Inc. FLUOREL is a registered trademark belong-
.ing to 3M Co. After some high temperature tests, center
element 37 would still be in a liquid or near liquid state
when packer 20 was removed from the test facility. However,
'1~-
sealing unit 30 withstood high differential pressures in
either direction when end elemen~s reinforced wi~h wire mesh
were used. As will be later explained, the geometry of the
end elements 36 and metal backup rings 33 results in increas-
ing the differential pressure capabilities of sealing unit 30
- and allowing selective compression of the packing elements.
The present inv~ntion includes means for releasing packer
20 from the inner wal.l of casing string 25 by merely applying
a preselected amount of upward tension to tubing string 21.
In FIGURES 3A, 3B and 3C, packer 20 is shown being pulled from
the casing (not shown) by tubing string 21. When a prese-
lected amount of tension is applied to tubing string 21,
screws 35 will shear into two portions 35a and 35b~ Mandrel
means 22 is then free to slide longitudinally in the one
direction relative to slip means 50. Sealing unit 30 is also
now free to slide over the exterior of mandrel means 22.
A first shoulder 95 is formed on the exterior o mandrel
means 22 adjacent slip means 50. First slip expander ring 52
has a partially enlarged inside diametex 63 which forms a
matching shoulder 64. When mandrel means 22 moves a prese-
lected distance relative to slip means 50, first shoulder 95
will engage first expander ring 52 and pull camming surface 57
from behind slip means 50.
A second shoulder 97 is formed on the exterior of mandrel
means 22 and spaced longitudinally from first shoulder 95.
When mandrel means 22 has moved a preselected distance rela-
tive to slip means 50, second shoulder 97 will move collet
support ring 60 from underneath collet fingers 59. Collet
fingers 59 can then flex inwardly releasing second expander
ring 53 from behind slip means 50.
As shown in FIGURE 3B, first expander ring 52 has been
lifted by first shoulder 95 from behind slip means 50~ Lugs
,
-12-
54 on expan~er 52 are at the top o~ guide slots 56aO Lower
expander ring 53 has dropped from behind 51ip means 50. Lugs
54 on expander ring 53 are resting at the bottom of guide
slots 56b.
Each slip means 50 is connected to the other by three
garter springs lOOat lOOh and lOOc. The garter springs sur-
round mandrel means 22. Each garter spring is disposed within
a separate hole in the body of each slip means 50. Garter
springs lOOa, lOOb and lOOc provide a means for biasing slip
means 50 inwardly away from casing 25. The both of slip means
50 is formed from a segment of a cylinder. The radius of the
outside diameter of slip means 50 is preferably selected to
match the radius of the inner wall of casing 25. The cross
section of slip means 50 is generally rectangular with lips
projecting from each end to retain slip means 50 within hous-
ing 55-
A third shoulder 98 is formed near end 22b of mandrel
means 22. Second support ring 34 has a matching shoulder 99
formed on its inside diameter. When screws 32 and 35 are
~ 20 sheared, sealing unik 30 can slide freely over the ex*erior of
; mandrel means 22. Third shoulder 98 provides a means for
catching sealing unit 30 and preventing it from falling off
while packer 20 is being removed from the casing. The third
position for sealing unit 30 is defined when both shear screws
32 and 35 are sheared.
As best shown in FIGURE 3A, longitudinal movement of
mandrel means 22 in the one direction relative to slip means
50 results in piston 46 and piston seals 47 becoming disen-
gaged rom piston housing 41. ~ariable volume ~luid chamber
48 is llOW opened at one end which establishes a communication
flow path thrsugh ports 43 and 44 to equalize fluid pressure
between the exterior of packer 20 and longitudinal flow
-13-
passage 23. Equalizing any difference in pressure is an
important step in releasing packer 20 from casing ~5~
As previously mentioned, packer 20 of the present inven-
tion is particularly adapted for use with high temperature and
pressure fluids. Center element 37 and end elements 36a~ 36b,
36c and 36d form a direct seal between mandrel means 22 and
the inner wall of casing 25. Sealing unit 30 thus prevsnts
the hot fluids fxom contacting the inner wall of casing 25
above packer 20. Variable volume chamber 48 is filled with
fluid while setting packer 20. This fluid within chamber 48
acts as a buffer to protect piston seals 47 from the hot,
possibly corrosive fluids flowing through longitudinal flow
passage 23.
One important feature of the present invention i~ that
the packing elements of seal unit 30 can be easily changed to
form various arrays for use with different well fluids. Third
shoulder 98 is preferably a C-ring or snap ring which can be
quickly removed from an annular groove near end 22b of mandrel
~ 22. Shear screws 35 can be removed allowing second support
; 20 ring 34 to slide off mandrel means 22. Backup rings 33, end
elements 36 and center element 37 are sized to be slidable
over the exterior of mandrel 22.
FIGURES 7-12 show various arrays of packing elements
which can be satisfactorily used with packer 20. The array
shown in FIGURE 7 comprises a center element 110 manufactured
from ethlene propylene-diene terpolymer, sometimes referred to
as EPDM. End elements 111 are preferably made from vinylidene
fluoride (VITON, a registered trademark ~elonging to DuPont)
or hexafluoropropylene copolymer (FLUOREL, a registered trade-
mark belonging to 3M Company). End elements 111 are prefer-
ably reinforced with wire mesh .005 inches in diameter andformed into a weave pattern .125 to .135 inches square. Six
-14-
:
to twenty layers of the wire mesh are contained within each
end element 111. Metal backup rings 112 are added on either
side of end elements 111. Metal backup rings 112 minimi~e
extrusion and lo~s of the elastomeric ma~erial when sealing
unit 30 is compressed.
FIGUR~ 8 shows an alternative end elements 113 made from
asbestos rings reinforced with wire. End elements 113 also
includes the unique cross section of the present invention
when sealing unit 30 is relaxed, The cross section of end
elements 113 is partially elliptical with the major axis of
the ellipse slanted towards the centerline of center element
110. The cross section of end elements 113 is further defined
by their inside and outside diameters being parallal cylin-
drical surfaces. As the packing array shown in FIGURE 8 is
compressed, the axis of the cross section of end elements 113
will move towards a less acute angle. Also, backup rings 112
are concaved to match the exterior of end ~lements 113. Metal
backup rings 112 are flexible and will deorm -to maintain
close contact with end elements 113 as the array is com-
pressed. The combination of the unique cross section and
matching conca~e, flexible backup rings results in first
compressing the center element and then the end elements.
Another alternative array is shown in FIGURE 9~ This
array comprises a center element 114 made from vinylidene
fluoride or hexafluoropropylene copolymer. At high tempera-
tures these compounds exhibit characteristics of more conven-
tional elastomers. End elements 115 are preferably reinforced
by wire .01 inches in diameter formed into a square mesh 0.18
to 0.25 inches on a side. Each element has 18 to 36 layers
per section. Asbestos cord and/or ceramic fibers are dis-
persed throughout the wire mesh.
,
-15-
FIGURE 10 discloses another packing array having
multiple end elements. ~wo rings 116 of virgin
polytetrafluoroethylene ~commonly referred to as TEFLON, a
registered trademark belonging to DuPont) are disposed on
either side of center element 110. Two rings 117 of
polyphenylene sulfide resin (commonly referred to as R~TON,
a registered trademark belonging to PhilLips Petroleum) are
next positioned adjacent rings 116.
FIGURE 11 shows an array in which center element 118 can
10 be either the same as center elements 110 or 114. End element
119 is preferably formed from laminated, ribbon packing made
out of carbon. This packing is sometimes referred to as
~RAFOIL, a registered trademark of Union Carbide Corporation
and disclosed in U.S. Patent 3,404,0610 Carbon packing ele
ment 119 is reinforced with wire mesh.
FIGURE 12 shows the final array of the present invention
comprising a center element 120 made from the same material as
ring 116. End elements 117 and 119 are used in combinaticn
with center element 120.
An alternative means for anchoring packer 130 incor-
porating the present invention to the inner wall of a casing
string is shown in FIGURES 16A, 16B and 16C. Packers which
are mechanically set by rotating tubing at the well surface
are well known. U.S~ Patent 3~385,366 discloses a packer
which is mechanically set by J-slots engaying a lug, drag
springs rubbing against the inner wall of a casing string, and
rotating the tubing.
Mandrel means 22 is essentially the same in both packer
20 and 130. The various co~ponents carried on the exterior of
mandrel means 22 between first expander ring 52 and third
shoulder 98 are identical and have been given the same number.
-16-
In packer 130 adapter sub 22c is used instead of adapter
sub 22a.
Adapter sub 22c is attached to and forms a portion of
mandrel means 22. The outside diameter of adapter sub 22c has
left-hand acme threads 131 fonmed theraon. Spring ~arrier 132
is rotatably secured to the exterior of mandrel means 22 by
engagement with acme threads 131. Boss 133 is welded to the
exterior of adapter sub 22c and spaced lvngitudinally from
threads 131. Boss 133 limits the longitudinal movement of
spring carrier 132 when carrier 132 is rotated to the left
with respect to mandrel means 22. Spring caxrier 132 is
generally cylindrical with three bow or drag springs 134
extending radially therefrom. Screws 135 are used to attach
bow spring 134, carrier 132 and first exparlder ring 52
together as a single rotating unit. Bow springs 134 are sized
to rub against the inner wall of a casing ~tring (IlOt shown).
When mandrel means 22 is rotated to the right, bow springs 134
limit the rotation of carrier 132 by dragging against the
inner wall of the casing. Left hand acme threads 131 thus
cause carrier 132 and first expander ring 52 to move longitu-
dinally in the one direction relative to mandrel means 22.
This longitudinal movement results in expander rings 52 and 53
moving towards each other radially projecting slip means 50
and compressing sealing unit 30 as previously explained.
For packer 130, xough surface 86 is preferably a triple
left-hand thread having the same pitch as ihreads 131. The
teeth on the inside diameter of wedge 83 are machined to match
rough surface 86. Therefore, internal 51ip means 80 will make
one revolution around mandrel means 22 in unison with spring
carrier 132.
Top sub 136 is engaged by thxeads to adapter sub 22c.
O-ring sleeve 137 is secured on the inside diameter of packer
130 between top sub 136 and adapter sub 22c. Top sub 136 has
lugs 138 which projects into the bore of packer 130.
The running tool used to install and set packer 130 com-
prises J-slot mandrel 139 disposed within the bore of top sub
136. J-slot mandrel 138 has threads 140 at one end for
attachment to a tubing string (not shown). J-slot mandrel 139
is releasably secured to top sub 136 by shear sleeve 141 and
; shear screws 142. Shear sleeve 141 prevents packer 130 from
disengaging from J-slot mandrel 139 while being installed in
- 10 the casing. Shear sleeve 141 has an internal shoulder 143
spaced lonyitudinally from a matching shoulder 144 on the
exterior of J-slot mandrel 139. The spacing between shoulders
143 and 144 allows for limited longitudinal movement of J-slot
mandrel 139 relative to top sub 136 without shearing screwfi
142. J-slots 145 are machined in the exterior of mandrel 139.
J slots 145 are sized for engage~ent with lugs 138. Rotation
of tubing (not shown) connected by threads 140 to J slot
mandrel 139 is transmitt~d to rotate top sub 136 by lugs 138.
Polished sleeve 146 is attached to the end of J-slot
mandrel 139 opposite threads 140. Preferably, the exterior of
polished sleeve 146 has a smooth, honed surface to form a
fluid tight seal with 0-ring~ 147 on the inside diameter of
'~ 0-ring sleeve 137.
Packer 130 is attached to J-slot mandrel 139 as shown in
FIGURE 16A and run into the bore of a casing string ~not
shown) by a tubing string (not shown) attached to threads 140.
When packer 130 has been lowered to the desired depth inter-
mediate the ends of the casing string, the tubing string is
rotated to right. Rotation of the tubing string is trans-
mitted to J-slot mandrel 139, top sub 136 by lugs 138, and
mandrel means 22 by adapter sub 22c threadedly engaged with
top sub 136. Bow springs 134 drag against the inner wall o~
:
-18-
., .
the casing string minimizing rotation of spring carrier 132
Since spring carrier 132 does not rotate freely, lef~-hand
acme threads 131 cause spring carrier 132 to move in one
direction longitudinally with respPct to mandrel means 22. As
previously explained for packer 30, this :Longitudinal movement
in one direction results in first expander ring 52 moving
towards second expander ring 53 to project slip means 50
radially from mandrel means 22.
Threads 131 are preferably sized such that after fourteen
turns to the right spring carrier 132 will be disengaged from
mandrel means 22. As previously noted, threads forming rough
surface 86 and threads on the inside diameter of wedge 83 are
matched allowing this rotation to simultaneously move internal
slip means 80 in the one direction.
After slip means 50 initially engages the inner wall of
the casing string, J-slot mandrel 139 is lowered and rotated
to the left to engage lugs 138 in the short portion of J-slots
145. A presel~cted amount of tension is then applled to the
tubing string and J-slot mandrel 139 to fully engage slip
means 50 with khe casing and place sealing uni~ 30 in its
second position. When the tension is released from J-slot
mandrel 139, internal slip means 80 locks expander rings 52
and 53 in position relative to each other. After packer 130
is set J-slot mandrel 139 is released from lugs 138 and the
tubing spaced out as re~uired~
The foregoing description of the present invention is
only an explanation of some of the preferred embodiments.
Various changes and modifications will be readily apparent to
those skilled in the art without departing from the scope of
the invention which is defined in the claim~.
--19--
