Note: Descriptions are shown in the official language in which they were submitted.
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CLAIM OF PRIORITY FROM PROVISIONAL APPLICATION
This application is a lbri-nal utility application of and claiming priority
ftoin. (-'.S.
Provisional Application Serial No. 611279.019, .filed October I5.2009.
entitled "t. ltra-Short Slip
and Packing Element System." Gregg %V. StOut, inventor,
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CRO S-RE?FERENCL TO RELA` TID APPLICATION
This application is related its subject matter to Application Serial No.
12/653.155 filed
December 9, 2009 entitled "Subterranean Well Ultra-Short Slip and Packing
Element Sy tetim,
Gregg \V. Stout, in -entor.
:tit. 990Q9 ~
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$ BACKGROUND OF THE INVENTION
1. Field of the invention
This invention relates to duwnhoie tools for oil and as wells and similar
applications and
more particularly to improved wwell packers.
Description of Prior Art
Well packers are used to form an annular barrier between well tubing or
casing, to create
fluid barriers, or plus=s, within aibina or easing. or the control or direct
fluid within tubing or casing.
Packers maw- be used to protect tuhulars` from well pressures, protect
itihtrltrrs` from corrosive e fluids
or gases.. provide zonal isolation, or direct acid and frac slurries into
f.7rrrrations.
Typical well packers consist of a packer mandrel. Radially mounted on the
packer mandrel
is a locking or release mectaanism. a packing element system with gage rings,
and a s1ip~cone
system, _l.ltese packers tend to be 2 feet or longer depending on the packer
desiagn. The packing
system is typically an elastorrzeric packing element with various types of
backup devices such 'as
gage rings. The packing system is typically expanded outward, between the gage
rings to contact
the I.D. of the casing by a longitudinal compression force generated by a
setting tool or hydraulic
piston. This force expands the elastomer and any backup material to create a
seal betwween the
packer mandrel and casing I.D. This same longitudinal three acts through the
scaling system and
acts on the slip system. The slip system is typically an upper and lower cone
that slides under slip
segments and expands the slip segments outwardly until teeth on the O.D. of a
series of slip
segments engage the I.D. of the casing. Teeth or buttons on the O-D. of the
slip segments penetrate
the I.D. of the casing, to secure the packer in the casing, so the packer will
not move up or down as
pressure above or below the packer is applied. A locking system typically-
secures the seal and slip
systems in there outward engaged position in order to maintain compression
force in the elastorner
and, in turn. compression force on the slip system. Certain part
configurations allow the locking.
mechanism to disengage to allow retrieval of the packer. The presence of the
release rnechanisni
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usually classifies the packer as a "retrievable packer" and the absence of the
release mechanism
classifies the packer as a "permanent packer".
Problems with prior art packers. in some cases, can be the excessive length of
the packers
since all of the above combined system,, require length. It would advantageous
to tla\c a packer that
is much shorter in that reduced material would certainly lover material and
manufacturing costs. It
would be advantageous to have a very short packer. so if packer removal is
retquired, milling time
would be greatly reduced. Some of the drillable fray: plugs on the market are
the Flailiburron
"Obsidian Frac Plug.", the Smith Services "D2 Bridge Plug-, the Owen Type "A."
Frac Plug. the
Weatherford "FracGuard". and the BJ Services "Phytlion". By comparison. all of
these plug designs
are very long in comparison to the current invention. Also, a very short
packer would reduce cost
and simplify the task of creatimM, a "Pass-through" packer. "Pass- through"
packers are used for
intelligent well completions and allow the passage of, for example and not
limited to, hydraulic
control lines. fiber optic limes, and electrical lines.
Both retrievable and permanent packers are sometimes drilled or milled out of
the casing. If
the packer is being used as a `'Frac Pfug". a Halliburton trademark. it is
commonly milled out after
the frac is completed. "Typical packers, as described above, tend to have mill-
out problems because
the packer parts tend to spin within the engaged slips. The mill operation
becomes very inefficient
because the packer parts spin with the rotation of the milling tool. Some
packer designs exist, for
example the BJ Services Patent 4 6.708.770, to reduce this spinning tendency.
It would he
advantageous to have a packer design that would offer alternative features to
prevent spinning of
parts while milling out. It would also be advantageous if this same design
feature ,would provide a
means to equally distribute the slip segments around the packer body to evenly
distribute the load
on the I.D. of the casing.
Another problem is that the slip system is loaded through the packing element
system
without a fully supported packing element to prevent extrusion, Extrusion of
the packing element
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system reduces stored energy in the slip system thus allowing the slip system
to disengage,
especially during pressure rev=ersals. the casing and in turn cause packer
slippage and seal failure.
Typical packers have a seal system that has elastomers backed up by anti-
extrusion devices and the
anti-extrusion devices are nicked up by age rinLS, f he gage rins`s I 'picalh
have a built-in
extrusion gap between the O.D. of the age ring and the I.D. of the casing to
provide running
clearance for the packer. The built-in extrusion gap can he a problem and is
commonly the primary
mode of seal system failure at higher temperatures and pressures. This is
because the elastomers and
backup devices tend to move into the extrusion gaps. When this movement
occurs, the stored
energy is lost in the seal system and the seal engagement is jeopardized to
the point of seal failure.
It would be an advantage to remove the majority of the extrusion gap to
prevent the seal from
extruding or mov-=in,,. Attempts have been made to reduce the extrusion gap by
use of expandable
metal packers, for example, the Baker expandable packer patent numbers US
7.134504 1:12, US
2005/0217869, and US 6,959,759 B2. or the Weatherford Lamb metal sealing
element patent =r' US
20051023100 Al.
Typical retrievable packers have slip systems that. when expanded, contact the
I.D. of the
casing at 45 degree or 60 degree increments around the I.D. of the casing.
Each slip segment has a
width and there is typically a space between each slip segment. The space
between each slip
segment creates a surface area where no slip tooth engagement occurs. The
total slip contact with
the I.D. of the casing may, for example. only be 50% of the surface area on
the inside of the casing.
If pressure is applied across the packer, the slips are driven outward into
the casing. It is a problem
in that due to the incremental contact on the l.D. of the casing, high non-
uniform stresses in the
casing wall can cause deformation or even failure of the casing wall. it would
be very desirable to
have a slip system that approaches a full 160 degree contact in the I.D. of
the casing to minimize
damage to the casing. Also, with slip engagement approaching 360 degrees,
there is more slip tooth
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engagement due to increased radial surface contact area, thereby providing the
opportunity' to
reduce length of the slit>. Reduced lean h olthe slits then reduces the
overall length of the. pack-cr.
Typical permanent packers have slip systems that "break". Slips that "break-
approach the
360 degrees of contact. These slips are usually made by manufacturing a ring.
cutting slots in the
ring to create break points. and then treating the teeth on the U.D. of the
ring for hardness purposes.
When longitudinal load is applied to a cone. the cone moves under the slip
ring and the ring tends to
break at the slots to create slip segments. I listory has shown that the slip
se` ment, break unevenly
or don't break at all. break at different Forces, and engage the I.D. of the
casing in irregular patterns.
These breaking problems can reduce the performance and reliability of the
packer. It would he
advantageous to have slips that approach the 360 degrees of contact and are
not required to break.
1 dont require a variable force to break, and evenly distribute themselves
around the J.D. of the
casing.
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St IMARY OF THE I\VFNTION
,-lr; .
l.s invention provides a .ti improved packer Or ~..LLtecl wells or for a
tubular member
positioned inside of easing. The invention includes a number of features that
overcome the above
mentioned problems. A ~ very short and simple packer design. \ itla I :rtttres
that increase. overall
packer reliabilit1, is created by eflecti-velti combining synetgi s o1 the
cone. slip and seal elements
to work in unison.
This packer can be set on standard electric w,~-ireline or with hydraulic
setting tools conveyed
on jointed pipe or coiled tubin<g.
The packer can be,, ready modified to serve several applications: 1) A
hydraulic setting
cylinder can be added so the packer can be run as part of the casing or
tubing; 2~) the packer can
utilize a fixed frangible disc or a flapper de\ ice to serve as a bridge plug,
frac plug, or a preferred
title, a "Frac Disc". The materials of the packer can be optimized to reduce
nmill-out time. Mill-out
time is greatly reduced due to the very short length of the packer, around 4",
so expensive
composite materials aren't necessarily retluired, 3) a seal bore can easily be
attached to the packer
body, 4) since the slip system creates a metal-to-metal inter!-ace with the
I.D. or the casing, the
packer can readily be adapted to a high pressure and temperature well
environment., a_) the packer
can address applications as simple as loGx cost plug and abandonment to highly
complex
applications in hostile environment wells, and 6) the packer, due to it's
short length, is ideal for
incorporating ``control line pass-thru" for intelligent well completions.
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BRIEF DESCRIPTION OF THE DRAWINGS
Finurel is a schematic view of the present invention in the -rul'tI1in2
position-,
Fiatire 2 is a schematic view of the present invention in the -set position".
Figure 3 is a cross sectional end vier of the packer mandrel and slip segments
of the pr sent
invention in the hilly exptmdeci "set position".
fieure 4 shos three views Ma slip segment that demonstrates an alternate to
teet1 .
Figure 5 is a schematic view of the present invention, less the tipper slip
segments, in the -set
position".
Figure 6 is a schematic of the present invention in the set position, further
simplified with use of a
packer cup rather than a compressed packing element.
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DETAILED DESCRIPTION OF TI-IE PREFERRED EMBODIMENTS
With reference to figure 1. a schematic of the present Ãn ention shows a 180
degree
letwthwise cross-section of the packer. A mandrel I has a running thread 16
with a tension or shear
parting point. or connection, 17 located boleti, the running thread. 1'he
mandrel I may be shortened
by more than one means at point 17- i.e.. an type of shear, tension, or
locking device that can be
separated in a fashion to shorten the mandrel. A setting tool (not shown) is
made up to running
thread 16 in order to convey the packer into the yell. A millable, frangible
or disintegrable disc 14
is a fluid barrier and is part of mandrel 1 or can be attached and scaled to
mandrel I in sonic
fashion. Cone surface 3 is shown of the O.D. of mandrel I.. Slip segments 4
are expandable by
1$ sliding up coned surfaces at 2 and 3. Seat 5. commonly known as a packing
element. is located
between slip segments 4 and extrusion barriers 6. Seal 5 is compressed and
expanded between slip
segments 4.
1`he slip segments 4 have gaps between theltl that increase in size as the
slip segments travel
up the cones 2 and 3. The extrusion barriers 6 are segmented and attached to
the slip segments 4 so
that the gaps between the slip segments 4 are always bridged to prevent
extrusion of Seal 5 as the
slip segments 4 travel outward to meet the I.D. of the casing. As an
alternative, the extrusion
barriers 6 may be manufactured as part of the slip segments 4 so that the slip
segments 4 themselves
bridge the gaps between the slip segments as the slip segments expand outward.
Shear pines 7 secure
the slip segments 4 in the retracted position while the packer is run into the
well.
The slip segments 4 have dovetail shaped runners 12 that slide in dovetail
grooves 1.1 at
cone surfaces 3 and 2. The runners 12 and grooves i i may be of any profile
and serve to retain the
slip setigments to both mandrel I and cone 8. Furthermore, the runners and
grooves provide a= means
to equally space the slip segments 4 around the perinicter of the pludgg.
Additionally. the runners and
grooves provide a means to rotationally lock the slip segments 4, the mandrel
1, the cone 8. and the
,0 lock ring 9 together during milling operations. When the slip segments
engage the inner casing wall.
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all components become rotationally locked together to help prevent spinning of
the packer parts.
The lock ring 9 threads are arranged in a manner so it right-hand rotation
during milling rotates lock
ring 9 to the right. the lock ring 9 rotates down thread 101, until it bottoms
out at the end oi' thread
10. Once bottomed out, it 9 becomes rotationally locked to the mandrel 1.
rotationally locked to the
cone 8, which is rotationally locked to slip segment 4. while the teeth 19 of
slip segment 4 are
penetrawd into the inner casing wall.
The slip segments 4 are positioned almost 360 degrees around the (-i.D, of the
mandrel 1.
Each slip segment has a series of teeth 19, or some other casing penetrating
profiles such as hard
inserts positioned on the O.D. of the slip segments as shown in Figure 4.
In Figure 4 the sli 5r;,' .ent 4 is shorn Without teeth 19. but instead
inserts or co nng 25.
Inserts or coating 25 may be ceramic balls, carbide balls, other geometries
made of carbide or
ceramic, pronpant or sand. or other materials. Inserts or coatings 255 may be
of any pattern on the
O.D. of slip segment 4 and can be either a structured or random pattern. Sand
or proppant. for
example 20-40 or larger sizes, gravel pack sand or fracturing proppant made by
Santrol or Flexion.
or Carboceramics. can be used in or on the surface of slip segment 4 and can
be attached to the
surface with bonding materials or imbedded into the base material. Those in
the gravel pack. or frc
pack business know that sand or proppant can stick downhole tools in the well,
so it would he
obvious that sand or proppaitt can be used on packer slips to hold tools in
place relativ to pipe or
casing. The objective of using inserts or coatings 25 is to improve
millability of the slip segments
whereby the base material. of the slip segments are easily machined and the
inserts or coating 25 :_1r
hard en1ot1111 to penetrate the casing 1.D. Another objective to inserts or
coating 25 is to inininliae
casing damage on the I.D. of the casing. Teeth marks from slips can increase
susceptibility of th
casing to corrosion and other failure mechanisms. especially.in chrome based
materials. The teeth,
inserts, or coatings are sufficiently hard to penetrate the inside of the
casing wall in order to grip the
wall and prevent the packer from moving relative to the casing.
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The slip segments have ,in O.D. that is machined to be almost equal to the
I.D. of the casin(11.
The slip segments are machined to minimize any gaps between the 0.1). of the
slip segments and
the I.D. of the casing. Similarly, the angles on the I.D. of the slip segments
are machined to almost
match the O.D. of the cone surfaces'. and 3 when the slip is fully expanded,
in order to ntirti.nizc.
gaps between the parts.
i U The cone 8 has a surtat e 2. l l)c s toil tool (,nf)t sho,,w,n;) pushes
against surface 18 'Mille
pulling on threads 16 during the setting operation. the cone 8 has an internal
thread that enga`ces
body lock ring w 9. Body lock ring 9 can ratchet freely toward the slip
segments 4 but engages and
prevents movement away- from the slip segments 4 by engaging the threads 10 on
the top O.D. of
the mandrel 1. lugs 13 engage slots 15 if plugs stack during milling so the
relative plugs don~t spin
15 during milling.
Figure 2 shows the packer in the "set position". In operation, also see Figure
I , the setting
tool tnot shown) pushes on cone 8, a or near surface 18, and sin ultaneously
pulls on thread 16 of
a aandrel 1. Cone 8 moves toward the slip segments 4 and seal 5 and in the
process expands the slip
segments 4 rip cones 2 and 3 and compresses Seal 5 between slip segments 4 and
extrusion barriers
0 6. Expansion of slip segments 4 and seal 5 continues until sufficient
contact is made with the I.D. of'
the casing to achieve slip tooth 19 penetration in the inner E .all of the
casing.
At this point the teeth of the slip segments have nearly closed any seal 5
extrusion gaps
between the O.D. of the slip segments 4 and the I.L. of the casing. Extrusion
gaps have been
minimized nearly 360 degrees around the packer. Additionally, slip load has
been nearly evenly
25 distributed around the I.D. of the casing to minimize distortion of the
casing.. Slip segment. 4
distribution around the O.D. of the mandrel I is more uniform due to the rails
12 and grooves I.I.
keeping the slip segments equally spaced around the packer. Also, extrusion
gaps have been closed
where the I.D. ofthe slip segments contact the surfaces of the cones at 20 and
21. At this point, the
extrusion gaps between the slip segments 4 are bridged with the extrusion
barriers 6.
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In the set position. Figure 2, the lock ring; 9 has traveled over thread 10.
Thread 10 is desiffed to
prevent reverse movement of lock rim 9. so that lock rung 9 holds cone 8 in a
firm position under
slip segment 4 while nmaintainin compression on seal S and keeping the slip
segments 4 expanded
into the I .D. of the using. Once sufficient load is applied to cone 8 and
thread 16 ol` mandrel 1, in
order the drive teeth 19 into the 1.D_ of the casing and create an adequate
seal with seal 5. the upper
portion of mandrel I with thread 16. disconnects at point 11. The tipper
portion ? of mandrel 1
comes out of the hole with the setting tool (not shown) and leaves a short
section of mandrel 1 in
the well.
Obviously. with the outer packer comp o7rtents 4.5, and S compressed closely
together in
1, combination with the short section of mandrel 1. the remaining portion of
the plug is not only very
short. but requires less material and length to mill out. Die amount of
material to mill out is
minimized by taking as much material out of the packer components as possible,
while still
maintaining enough strength to hold well pressure differentials. For example,
notice on mandrel I
that the LI.). is bored out and at the lower end of mandrel 1 below- the
angled surface 3. material has
been removed at location 23. As a result, the packer becomes a minimum
material packer by
removing material that is not needed to structurally maintain a pressure
differential in the well bore.
Also, to enhance millahility of the packer, highly rnillable materials may be
used, such as cast iron.
or some other easily machinable material.
Figure 3 shows a cross-sectional end view of the slip segments 4 in the
expanded position.
In the expanded and set position, gaps exist between each slip segment. 4. An
extrusion barrier 6 is
attached to the slip segment 4 by an attachment means, such as drive-loe pins
24_ 'the extrusion
barriers 6 cover the gaps between each slip segment 4 to form a seal S backup
surface to prevent
seal 5 extrusion past the slip segments 4. Since the teeth 19 of the slip
segments penetrate the inside
of the casing wall. any extrusion gaps are closed oft:' on the outside of the
slip segments 4. Since the
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1.1). cti'the slip segments 4 closely matched the O .D. of the tapered
surfaces 2 and 3. the extrusion
gips on the insid ; of the slip segments 4 are reduced to a mini Tzum_ 1 Ills
ddcserib,'d -conictry forms
a near metal to-metal seal backups stem in the packer vhich 1s very desirable
f r tiigh pressure and
temperature well conditions.
Figure 5 shokks a similar packer. or Frac Disc, to Figure 1. The Figure 5
packer has the sane
features mentioned above except it does not have an upper set of slip segments
3 . therefor. it
would normally be used in situations where the packer is only required to hold
pressure fioni above.
This version would be a 1otver cost version than the one sho\.~n in Figure 1
and cone 8 could be
replaced with lock ring housing 26. In order to further simplify the packer
design, the extrusion
rings 6 could he eliminated and the packing element, or seal 5, could have a
backup built into the
seal system 5. In low pressure applications- or in cases There a positi,,e
seal with the I. D. of the
casing is not needed, extrusion backup 6 and other backups in the packing
element could be
eliminated.
Figure 6 shows a similar packer. or f'rac Disc, to Figure 1. The Figure 6
packer has many of
the same features mentioned above except it does not have the upper set of
slip segments 4, or the
packing element 5, or the anti-extrusion devices 6. The cone S is replaced
with cup retainer 27 and
the packing element 5 is replaced with the packing cup 28. Obviously the
packing cup 28 only holds
pressure from above generated from pressure operations occurring above the
cup. This design
allows opportunities to further minimize the material left in the well for
milling out, for example. by
eliminating the upper slip segments 4 and leaving a shorter mandrel 1 h
moving, separation point
17 downward.
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