U.S. patent application number 12/696805 was filed with the patent office on 2011-08-04 for asymmetric seal and method.
This patent application is currently assigned to BAKER HUGHES INCORPORATED. Invention is credited to Richard Xu.
Application Number | 20110186308 12/696805 |
Document ID | / |
Family ID | 44340631 |
Filed Date | 2011-08-04 |
United States Patent
Application |
20110186308 |
Kind Code |
A1 |
Xu; Richard |
August 4, 2011 |
ASYMMETRIC SEAL AND METHOD
Abstract
A seal including a contact area; and two arms extending in
opposite directions from the contact area, the seal when set
exhibiting an asymmetric cross section.
Inventors: |
Xu; Richard; (Tomball,
TX) |
Assignee: |
BAKER HUGHES INCORPORATED
Houston
TX
|
Family ID: |
44340631 |
Appl. No.: |
12/696805 |
Filed: |
January 29, 2010 |
Current U.S.
Class: |
166/387 ;
277/322 |
Current CPC
Class: |
E21B 33/128 20130101;
E21B 33/12 20130101; E21B 33/00 20130101 |
Class at
Publication: |
166/387 ;
277/322 |
International
Class: |
E21B 33/128 20060101
E21B033/128; E21B 33/12 20060101 E21B033/12; E21B 33/00 20060101
E21B033/00 |
Claims
1. A seal comprising: a contact area; and two arms extending in
opposite directions from the contact area, the seal when set
exhibiting an asymmetric cross section.
2. A seal as claimed in claim 1 wherein the two arms are deflected
radially by a differing number of degrees from one another.
3. A seal as claimed in claim 2 wherein the number of degrees of
deflection of one arm ranges from about 45 to about 50 degrees from
an axis of the seal.
4. A seal as claimed in claim 2 wherein the number of degrees of
deflection of one arm ranges from about 40 to about 45 degrees from
an axis of the seal.
5. A seal as claimed in claim 3 wherein the number of degrees of
deflection of the other arm ranges from about 40 to about 45
degrees from an axis of the seal.
6. A seal as claimed in claim 1 wherein the two arms are of
different length.
7. A seal as claimed in claim 6 wherein a shorter of the two arms
ranges from about 90 percent of the length of the longer of the two
arms to about 97 percent of the length of the longer of the two
arms.
8. A seal as claimed in claim 1 wherein the seal further comprises
a groove associated with each arm.
9. A seal as claimed in claim 8 wherein one of the grooves is of
smaller axial dimension to limit radial deflection of one of the
two arms.
10. A seal as claimed in claim 9 wherein the smaller groove is
about 70 percent to about 80 percent of the axial dimension of a
larger groove of the grooves.
11. A method for sealing an annulus comprising: running a seal as
claimed in claim 1 to a target location; and setting the seal at
the target location in a cross sectionally asymmetric
configuration.
Description
BACKGROUND
[0001] Annular seals for the drilling and completions industry have
been known for many years and have benefitted over those years with
improvements in material composition, setting strategies and
systems, etc. Presently there are numerous types and kinds of seals
available on the market. Notwithstanding ubiquitous solutions
however, the number of possible situations is not finite and hence
there is no end to the need and or desire for additional
modifications to existing seal structure or design and indeed the
development of entirely new concepts in sealing technology.
[0002] One type of annular seal uses a relatively thin wall portion
of a tubular form that is intended to bulge outwardly upon axial
compression and/or fluid pressure. Such seals employ a central
area, sometimes including one or more pips, that is radially forced
into contact with a casing. The portions of the seal sometimes
referred to as arms, on either side of the central area create
roughly symmetrical frustocones upon setting of the seal. Such
seals can be constructed of metal, plastic, rubber, etc. and
generally include an o-ring at a mandrel thereof to prevent fluid
movement past the seal once it is set. Typically the O-ring is
disposed at one end of the seal. O-rings are generally not placed
at both ends of the seal as in the event that a liquid fluid filled
the open space defined by the seal, it might well be impossible to
set due to the relative incompressibility of liquid fluids. These
seals have performed well for their intended purposes but do
improvement as noted above is always desired. Accordingly the art
will well receive seals having greater function.
SUMMARY
[0003] A seal including a contact area; and two arms extending in
opposite directions from the contact area, the seal when set
exhibiting an asymmetric cross section.
[0004] A method for sealing an annulus including running a seal as
claimed in claim 1 to a target location; and setting the seal at
the target location in a cross sectionally asymmetric
configuration.
BRIEF DESCRIPTION OF THE DRAWINGS
[0005] Referring now to the drawings wherein like elements are
numbered alike in the several Figures:
[0006] FIG. 1 is a schematic view of a prior art seal cross section
in a set position;
[0007] FIG. 2 is a schematic view of an embodiment of an asymmetric
seal as disclosed herein that shows pressure acting on the seal
from an end thereof that includes an o-ring seal;
[0008] FIG. 3 is a schematic view of the same embodiment of an
asymmetric seal as in FIG. 2 but showing pressure acting on the
seal from an end thereof that does not include the o-ring seal;
[0009] FIG. 4 is a schematic section view of another embodiment of
an asymmetric seal as disclosed herein in a run in position;
[0010] FIG. 5 is the embodiment of FIG. 4 in a set position.
DETAILED DESCRIPTION
[0011] Referring to FIG. 1, one of ordinary skill in the art will
recognize a type of seal 10 known to the art. The seal 10 includes
a contact area 12 that is positioned between two frustoconical
(when in the set position as illustrated) arms 14 and 16 and two
end rings 18 and 20. Each end ring also includes a groove,
illustrated as 22 and 24 in FIG. 1 to promote radial movement of a
central portion of the seal 10, i.e. the contact area 12 and the
arms 14 and 16. Finally the seal 10 includes a mandrel seal such as
an o-ring 26 positioned at one end of the seal 10. The O-ring seal
26 prevents pressure leakage between the seal 10 and a mandrel 28
but note that the o-ring 26 is positioned at only one end of the
seal 10 to avoid potential hydraulic locking of the seal 10. This
means to that pressure acting from one end of the seal is borne
differently than from the other end of the seal. This is further
discussed hereunder. With respect to FIG. 1, it is important to
note in the illustration is that the two frustoconical arms 14 and
16 are generally symmetrical. The invention is distinct in this
regard.
[0012] In accordance with the disclosure hereof, and referring to
FIGS. 2 and 3, the inventor has discovered that an asymmetrical
seal 110 performs better than the configuration of FIG. 1. The seal
110, it will be appreciated, has one arm 114 that is shorter than
the other arm 116. The arm that is shorter should be the one that
is on the same end of the seal 110 that the o-ring 126 is on. In
this illustration, the one that is shorter is 114. It is important
to have the shorter arm on the end with the o-ring 126 because of
the way that pressure sources from one end of the seal 110 are
borne versus pressures from the other end of the seal are borne. It
is not relevant whether the pressure is from uphole, downhole, or
any other direction indicator but rather only whether the pressure
from a particular end of the seal will have access to an inside
surface 130 of the seal 110 or not. Pressure that comes from an end
of the seal 110 that does not have the o-ring will have access to
the inside surface of the seal whereas pressure from an end of the
seal 110 that does have the o-ring 126 will not have access to the
inside surface 130 of the seal.
[0013] As can be seen in FIGS. 2 and 3, the result of the longer
arm 116 upon setting is that it achieves a shallower angle relative
to the mandrel 128 or axis of the seal 110 than the angle achieved
by the shorter arm 114. Angle ranges for the arms 114 and 116 is
about 45 degrees to about 50 degrees and about 40 degrees to about
45 degrees, respectively relative to a longitudinal axis of the
seal 110. Such a configuration has been shown via Finite Element
Analysis to improve pressure rating for the seal 110 over similar
symmetrical seals 10. It is believed that the shorter arm 114 at a
higher angle has greater rigidity against the pressure on an
outside surface 132 of the seal, see arrow P.sub.o, which stands
for pressure o-ring end. This is helpful since pressure from that
end of the seal, due to the location of o-ring 126, is borne only
at surface 132 and the seal 110 is not assisted from the inside
surface 130. The longer arm 116, although it is necessarily less
rigid due to length, benefits from the pressure from its end of the
seal on surface 130 thereby reducing the ultimate load on the seal
from the outside surface 134, see arrows P.sub.no, which stands for
pressure non o-ring end. In other words, because the pressure
affects both inside 130 and outside 134 of the seal 110 from this
direction, the pressure differential directly across the arm 116 is
insignificant and therefore the reduced rigidity of the longer arm
116 is of no consequence. The length of the shorter arm 114
relative to the longer arm 116 is in one embodiment in the range of
about 90% to about 97% of the length of the longer arm 116.
[0014] Referring to FIGS. 4 and 5, an alternate embodiment
asymmetrical seal 210 is illustrated. The ultimate set position of
this embodiment is similar to the foregoing described embodiment in
that one arm achieves an angle relative to the mandrel 228 or
longitudinal axis of the seal 210 that is greater than an angle
achieved by the other arm but it does not require that the length
of the arms differ. Rather, in this embodiment it is grooves 222
and 224 that are distinct. Configuring a groove 222 or 224,
(depending upon which groove is proximate the o-ring 226, which is
groove 222 in the illustration) with a limited amount of space used
for accommodation of the arm associated therewith. Stated
alternatively, the amount of space available within a groove can be
a limiting factor in how much radial movement the arm can
experience. By carefully sizing the grooves 222 and 224, one can
ensure that one arm will deflect radially outwardly less than the
other arm thereby ensuring that the arm that is allowed to deflect
farther will achieve a greater angle relative to the mandrel 228 or
an axis of the seal 210 resulting in an asymmetric seal cross
section. This configuration has been noted above to exhibit
improved results over the seal 10 of FIG. 1. The Seal configuration
of FIG. 3 thus is also beneficial to the art. The groove size
limitation that is contemplated is that the smaller groove is in a
range of from about 70% to about 80% of the size of the larger
groove, the larger groove being the one that is proximate the
O-ring 226.
[0015] While each of the configurations discussed above are capable
of achieving the favorable results of better pressure ratings over
the seal 10 of FIG. 1, this is not to say that the two
configurations cannot be combined. To the contrary, the
above-disclosed concepts can indeed be combined if desired.
[0016] While one or more embodiments have been shown and described,
modifications and substitutions may be made thereto without
departing from the spirit and scope of the invention. Accordingly,
it is to be understood that the present invention has been
described by way of illustrations and not limitation.
* * * * *