Note: Descriptions are shown in the official language in which they were submitted.
CA 02716685 2010-10-07
MULTI-PIECE PRESSURE OPERATED RINGS
FOR A DOWNHOLE PUMP PLUNGER
This application claims priority on US Patent Application No. 12/575,211 filed
October 7, 2009, incorporated herein by reference.
FIELD OF THE INVENTION
This invention relates to improvements in oil well pumps and more particularly
to
seal rings used in reciprocating subsurface oil well pump assemblies.
BACKGROUND OF THE INVENTION
A typical reciprocating subsurface oil well pump consists of a plunger and
travelling check valve in reciprocating relationship within a stationary
working barrel
formed as a part of the oil well production tubing. The working barrel itself
is provided
with a standing valve and submerged usually in well fluid. The pump is
normally
secured to the lowermost end of a sucker rod string, which extends
longitudinally through
production tubing situated in the well bore. A reciprocating device at the
surface, either a
traditional "horsehead" type or more recent wire line winch, alternately
raises and lowers
the string of sucker rods in the well bore.
The wire line winch system typically includes a control means for rotating the
winch in one direction for the upstroke and controllably releasing the winch
in the reverse
direction for the downstroke. In such a system a weighted oil well plunger-
type pump
must be capable, during the upstroke, of providing adequate ring seals for
producing the
fluid, while on the downstroke, the seal rings must be capable of permitting
substantial
release of the plunger so that it will fall to its bottom dead center position
for the repeat of
the process.
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Plungers have been provided with various means for affecting the necessary
fluid
seal between the plunger and the working barrel. For example, U.S. Pat. No.
3,953,155
discloses a single-piece pressure responsive plunger ring arranged between
adjacent
spacers and shaped so as to expand radially in contact with the working barrel
by action
of the fluid being pumped. The ring has an annular groove in its upper surface
that is
tapered outwardly toward the outer face of the ring. The outer face of the
ring is then
tapered downwardly and inwardly to form a lip around the outer edge. During
the
upward stroke of the pump, an increase in fluid pressure causes the ring to
expand and
provide a seal with respect to the working barrel. The ring also has a gap to
facilitate
assembly onto the plunger and to facilitate radial expansion and contraction
of the ring.
As the ring wears through use, and as sand and other abrasive particles embed
into the
ring, pumping efficiency degrades and the ring must be pulled and replaced,
causing
downtime on the well and additional repair expense.
Various attempts to provide improved sealing and wear-resistance of plunger
rings involve protecting the ring from abrasive particles, changing the ring's
material
composition, and providing expansion and retraction capabilities. For example,
U.S.
Patent No. 5,752,814 discloses use of a plastic sleeve positioned above and
below the
ring to effect embedment of sand and other abrasive particles in the plastic
and protect
the ring. To thermally stabilize the sleeves and prevent their expansion due
to pumping
friction and elevated formation temperatures, a stainless steel or brass
insert must be
provided, further increasing the cost of the plunger assembly. U.S. Patent No.
5,372488
discloses a ring composed of metal and having two or more interlocking semi-
cylindrical
flat ring segments. To provide greater contact potential with the working
barrel, the outer
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face of the ring is not tapered. Similar to the operation of the U.S. Patent
No. 3,953,155,
during the upward stroke of the plunger, an increase in fluid pressure causes
the ring
segments to expand outwardly and provide a seal with respect to the working
barrel.
During the downward stroke, a decrease in fluid pressure causes the ring
segments to
retract.
The interlocking ring arrangement, however, has significant disadvantages.
Similar to the single-piece rings, the interlocking ring segments provide no
consistent
inter-space between the backside of the ring and the plunger when the ring
segments are
in their collapsed position, thereby requiring greater pressure for expansion
during the
upstroke and producing inconsistency in sealing efficiency between strokes.
Because of
the interlocking arrangement, a gap cannot be provided to facilitate radial
expansion and
contraction of the ring and allow for fluid flow to the backside of the ring.
Rather,
openings must be provided in the seal ring groove portion of the plunger in
order for the
groove to communicate with an interior flow channel and thereby allow fluid to
reach the
backside of the ring. In addition, reliefs located on the outer edge of the
ring segment
and opposite each interlock must be provided to prevent interference with the
top and
bottom sides of the groove when the ring segments are expanded. Sand and other
foreign
particles in the well fluid can cause misalignment of the interlocks and
interfere with the
ring segments' ability to properly expand and retract during operation,
potentially
increasing drag on the downward stroke and causing damage to the working parts
of the
pump. Therefore, a need exists for an improved, multi-piece plunger ring.
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BRIEF SUMMARY OF THE INVENTION
A pressure responsive seal ring assembly for use in a downhole submerged pump
assembly includes a plunger with a metallic cylinder and at least one seal
ring groove in
the cylinder for receiving a seal ring. The seal ring has two arcuate-shaped
ring segments
that interconnect in a non-locking manner. Each of the ring segments has a
first and
second end having an angular distance therebetween of less than 180 . A first
tab
extends beyond the first end of each ring segment and is received by a
recessed portion in
the first end of the opposing ring segment. A second tab extends beyond the
second end
of the second ring segment and is received by a recessed portion in the second
end of the
first ring segment. Under pressure the ring segments expand radially outward
and resist
fluid flow therebetween.
In a preferred embodiment, the seal ring includes a raised pad located on a
portion
of an inner peripheral surface of the ring segments. The pad provides an
effective inter-
space for a fluid flow between the inner peripheral surface of the ring and
the plunger
body. A pad is also preferably provided on the inner peripheral surface of the
first tab.
The tabs and recessed portions are preferably dimensioned so that a gap in an
outer periphery of the seal ring is formed when the ring is in its retracted
position. The
outside diameter of the seal ring in its retracted position is slightly less
than an inside
diameter of the working barrel in communication with the plunger. The gap,
however,
does not extend through to the inner peripheral surface of the ring. The seal
ring also
preferably has an annular groove in the upper surface of each of ring segment.
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In another preferred embodiment, the seal ring includes three arcuate-shaped
ring
segments. The ring segments include a tab-and-recess combination that
interconnect in a
non-locking manner similar to that of the two-ring segment ring assembly.
A better understanding of the invention will be obtained from the following
detailed description of the preferred embodiments taken in conjunction with
the drawings
and the attached claims.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is an isometric view of a plunger ring having two arcuate-shaped ring
segments that interconnect in a non-locking manner. A tab extension on each
ring
segment is received by an opposing recess in the other ring segment.
Figure 2 is an isometric view of the plunger ring in its assembled state.
Figure 3 is a top view of the assembled plunger ring. A number of pads located
on the inner periphery of the ring provide an inter-space for fluid flow
between the ring
and a plunger body.
Figure 4 is a cross-sectional view of the plunger ring taken along section
line 4-4
of Figure 3. An annular groove is provided on the upper surface of the ring
segment to
facilitate expansion and retraction of the ring segments.
Figure 5 is a cross-sectional view of the plunger ring taken along section
line 5-5
of Figure 3. Each tab extension is received by a recess in the opposing ring
segment and
a joint between the mated but not interlocked ring segments is formed.
Figure 6 is a top view of the first arcuate-shaped ring segment. The ring
segment
includes a tab extension and recessed portion on one end and a second recessed
portion
on the other end.
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Figure 7 is a front view of the first ring segment.
Figure 8 is a front view of the second arcuate-shaped ring segment. The ring
segment includes a tab extension at each end. A recessed portion on one end
receives the
tab extension of the first ring segment.
Figure 9 is a top view of the second ring segment.
Figure 10 is a front view of a tubular plunger having a number of seal ring
flanges. Seal ring grooves located between the seal ring flanges each receive
the first and
second ring segment.
Figure 11 is an isometric view of the plunger illustrating the assembling of
the
ring segments onto the plunger. The assembled ring segment provides a gap in
the outer
peripheral surface of the ring. The gap, however, does not extend through to
the inner
peripheral surface of the ring.
Figure 12 is a view of the plunger taken along section line 12-12 of Figure 11
and
shows the assembling of the ring segments in a seal ring groove.
Figure 13 is a view of the plunger taken along section line 13-13 of Figure 11
and
illustrating the assembled ring. The pads provide an inter-space for fluid
flow between
the ring and the plunger body.
Figure 14 is a top view of a three-piece plunger ring arranged about a section
of
the plunger. The ring segments include a non-interlocking mechanism similar to
that of
the two-ring segment ring assembly.
Figure 15 is an end view of the first ring segment taken along section line 15-
15
of Figure 14.
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Figure 16 is an end view of the first ring segment taken along section line 16-
16
of Figure 14.
Figure 17 is an end view of the second ring segment taken along section line
17-17 of Figure 14.
Figure 18 is an end view of the second ring segment taken along section line
18-18 of Figure 14.
Figure 19 is an end view of the third ring segment taken along section line 19-
19
of Figure 14.
Figure 20 is an end view of the third ring segment taken along section line 19-
19
of Figure 14.
Figures 21 to 23 illustrate the order of assembly of the three-piece plunger
ring
onto a plunger body.
Figure 24 is a view of the assembled three-piece plunger ring.
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DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The description that follows presents preferred embodiments for the purpose of
exemplification. Elements shown by the drawings are identified by the
following
numbers:
Plunger ring assembly 52 Pad 108 Second end
12 Annular groove 54 Pad 110 Extension
14 Inner side wall 56 First end 112 Pad
16 Inner face 58 Second end 114 Recess
18 Outer wall 60 Extension 120 Ring segment
Outer face 62 Pad 122 Pad
22 Lower face 64 Extension 124 Pad
24 Gap 66 Recess 126 First end
26 Joint 80 Ring segment 128 Second end
28 Joint 82 Pad 130 Extension
Ring segment 84 Pad 132 Extension
32 Pad 86 First end 134 Pad
34 Pad 88 Second end 136 Recess
36 First end 90 Extension 150 Tubular plunger
38 Second end 92 Pad 152 Working barrel
Extension 94 Recess 154 Central opening
42 Pad 96 Recess 156 Wall
44 Recess 100 Ring segment 158 Ring groove
46 Recess 102 Pad 160 Spacer flange
Ring segment 104 Pad 162 Circumferential space
106 First end 164 Inter-space
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Referring to the drawings and first to Figures 1 to 3, a pressure responsive
seal
ring assembly 10 for use in a downhole submerged pump assembly includes two
arcuate-
shaped ring segments 30 and 50 configured for non-interlocking arrangement.
Each ring
segment 30, 50 has an inner peripheral face 16, an outer peripheral face 20, a
10 substantially flat lower face 22, and an annular groove 12 located on an
upper surface.
Annular groove 12 is preferably arcuate-shaped, having a sloping inner wall
portion 14
and a sloping outer wall portion 18. See Figures 4-5 & 7-8. In a preferred
embodiment,
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the non-interlocking arrangement is accomplished by ring segment 30, 50 having
a first
end portion 36, 56 that lies within 180 of a second end portion 38, 58 and
tabs 40, 60, 64
that extend beyond one of the end portions 36, 56, 58 a sufficient distance to
engage a
matching recessed portion 44, 46, 56 located in the opposing ring segment 30,
50.
Tab 40, which is located on a lower interior portion of ring segment 30,
extends
past end 36 so that a distal end of tab 40 lies beyond an angular distance of
180 from
second end 38. The height of tab 40 is preferably substantially less than the
height of
ring segment 30 and the radius of curvature of tab 40 is preferably
substantially the same
as the radius of curvature for ring segment 30. See Figure 6. The lower
surface of tab 40
lies substantially co-planar to lower face 22.
A pad 42 is preferably provided on a portion of the inner peripheral face of
tab 40.
See Figures 5-7. The depth of pad 42, along with the depth of pads 32 and 34,
is
dimensioned to provide an effective inter-space between inner face 16 and an
exterior
surface of the plunger (not shown) for the flow of well fluid. Pads 32 and 34
are
preferably rectangular-shaped with the height of pads 32 and 34 preferably not
extending
in height equal to that of ring segment 30.
Lying adjacent to tab 40 is a recess 44 extending into ring segment 30 and
away
from end 36. The bottom surface of recess 44 lies substantially co-planar to
the top
surface of tab 40. The receiving depth of recess 44 is dimensioned to receive
tab 60 of
ring segment 50.
Tab 60, which is located on an upper interior portion of ring segment 50,
extends
past end 56 so that a distal end of tab 60 lies beyond an angular distance of
180 from
second end 58. The height of tab 60 is preferably substantially greater than
the height of
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tab 40, with the cumulative height of tabs 40, 60 being substantially equal to
the height of
each ring segment 30, 50. The radius of curvature of tab 60 is preferably
substantially the
same as the radius of curvature ring segment 50. See Figure 9. The lower
surface of tab
60 lies substantially parallel to lower face 22.
A pad 62 is preferably provided on a portion of the inner peripheral face of
tab 60.
See Figures 5 & 8-9. The depth of pad 62, along with the depth of pads 52 and
54, is
dimensioned to provide an effective inter-space between inner face 16 and an
exterior
surface of the plunger (not shown) for the flow of well fluid. Pads 52 and 54
are
preferably dimensioned the same as pads 32 and 34, respectively.
Lying adjacent to tab 60 is a recess 56 extending into ring segment 50 and
away
from end 56. The upper surface of recess 56 lies substantially co-planar to
the bottom
surface of tab 60. The receiving depth of recess 56 is dimensioned to receive
tab 40 of
ring segment 30.
Tab 64, which is located on a lower exterior portion of ring segment 50,
extends
past end 58 so that a distal end of tab 64 lies beyond an angular distance of
180 from
first end 56. The height of tab 64 is preferably substantially less than the
height of ring
segment 50 and the radius of curvature of tab 64 may be substantially the same
as the
radius of curvature for ring segment 50. See Figure 9. The lower surface of
tab 64 lies
substantially co-planar to lower face 22.
Lying opposite tab 64 is a recess 46 located in a lower exterior portion of
ring
segment 30. Recess 46 extends into ring segment 30 and away from end 38. The
bottom
surface of recess 46 lies substantially co-planar to the bottom surface of tab
64. The
receiving depth of recess 46 is preferably substantially equal to the length
of tab 64.
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When ring segments 30 and 50 are joined together, a joint face 28 normal to
inner
peripheral face 16 is formed as tab 64 is received by recess 46. The lengths
of tabs 40
and 60 and the receiving depths of recesses 44 and 56 are preferably
dimensioned so that
a gap 24 is formed in outer peripheral face 22 when recesses 44 and 56 fully
receive tabs
60 and 40, respectively. A joint face 26 is also formed.
Turning now to Figures 11 to 13, a tubular plunger 150 is positioned within a
working barrel 152 of a downhole pump assembly (not shown). Plunger 150 is of
a type
well-known in the art and typically includes a central fluid passageway 154
and a number
of seal ring flanges 160. Seal ring flanges 160 have an outside diameter
slightly less than
the inside diameter of working barrel 152, thereby providing a circumferential
space 162
between plunger 150 and working barrel 152. Located between each pair of seal
ring
flanges 160 is a seal ring grove 158 dimensioned to receive ring assembly 10.
Ring
segments 30 and 50 are assembled in the seal ring groove 158. In a collapsed
state, the
outside diameter of ring assembly 10 is slightly less than the inside diameter
of working
barrel 152. Pads 32, 34, 42, 52, 54, and 62 provide an inter-space between the
inner
peripheral face 16 of ring segments 30 and 50 and plunger wall 156.
During the upward stroke of the pump (not shown), an increase in fluid
pressure
causes ring segments 30 and 50 to expand radially outward and provide a seal
with
respect to working barrel 152. Annular groove 12, gap 24, and pads 32, 34, 42,
52, 54,
and 62 facilitate this expansion and improve surface contact of outer
peripheral surface
20 with working barrel 152. During the downward stroke, a decrease in fluid
pressure
causes ring segments 30 and 50 to retract radially inward. The pump cycle then
repeats.
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Ring segments 30 and 50 remain connected to one another throughout the pump
cycle in
a non-locking manner and resist fluid flow therebetween.
Referring now to Figures 14 to 20, in another preferred embodiment ring
assembly 10 includes three ring segments 80, 100, and 120 that assemble in a
non-
locking manner similar to that of ring segments 30 and 50. Ring segments 80
and 120
each have a first end portion 86, 126 that lies within 60 angular distance of
a second end
portion 88, 128, respectively. Ring segment 100 has a first end portion 106
and a second
end portion 108 that lie substantially 120 apart of one other.
Tab 90, which is located on a lower interior portion of ring segment 80,
extends
past end 86 so that a distal end of tab 90 lies beyond an angular distance of
120 from
second end 88. The height of tab 90 is preferably substantially less than the
height of
ring segment 80 and the radius of curvature of tab 90 is preferably
substantially the same
as the radius of curvature for inner peripheral face 16. The lower surface of
tab 90 lies
substantially co-planar to lower face 22.
A pad 92 is preferably provided on a portion of the inner peripheral face of
tab 90.
The depth of pad 92, along with the depth of pads 82 and 84, is dimensioned to
provide
an effective inter-space between inner face 16 and plunger wall 156 for the
flow of well
fluid. Pads 82 and 84 are preferably rectangular-shaped and the height of pads
82 and 84
preferably not extending in height equal to that of ring segment 30.
Lying adjacent to tab 90 is a recess 96 extending into ring segment 80 and
away
from end 86. The bottom surface of recess 96 lies substantially co-planar to
the top
surface of tab 90. The receiving depth of recess 96 is dimensioned to receive
tab 130 of
ring segment 120.
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Tab 130, which is located on an upper interior portion of ring segment 120,
extends past end 126 so that a distal end of tab 130 lies beyond an angular
distance of
120 from second end 88. The height of tab 60 is preferably substantially
greater than the
height of tab 90, with the cumulative height of tabs 90 and 130 being
substantially equal
to the height of ring segments 90 and 120. The radius of curvature of tab 130
is
preferably substantially the same as the radius of curvature ring segment 120.
The lower
surface of tab 130 lies substantially parallel to lower face 22.
A pad 134 is preferably provided on a portion of the inner peripheral face of
tab
130. The depth of pad 134, along with the depth of pads 122 and 124, is
dimensioned to
provide an effective inter-space between inner face 16 and plunger wall 156
for the flow
of well fluid. Pads 122 and 124 are preferably dimensioned the same as pads 82
and 84,
respectively.
Lying adjacent to tab 130 is a recess 136 extending into ring segment 120 and
away from end 126. The upper surface of recess 136 lies substantially co-
planar to the
bottom surface of tab 130. The receiving depth of recess 136 is dimensioned to
receive
tab 90 of ring segment 80.
Tab 132, which is located on a lower exterior portion of ring segment 120,
extends past end 128 so that a distal end of tab 132 lies beyond an angular
distance of
120 from first end 126. The height of tab 132 is preferably substantially
less than the
height of ring segment 120 and the radius of curvature of tab 132 may be
substantially the
same as the radius of curvature for ring segment 120. The lower surface of tab
132 lies
substantially co-planar to lower face 22.
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Lying opposite tab 132 is a recess 114 located in a lower exterior portion of
ring
segment 100. Recess 114 extends into ring segment 100 and away from end 108.
The
bottom surface of recess 14 lies substantially co-planar to the bottom surface
of tab 132.
The receiving depth of recess 114 is substantially equal to the length of tab
132.
Substantially similar to tab 132 is a tab 110 extending from end 106.
Substantially
similar to recess 114 is a recess 94 located in a lower exterior portion of
ring segment 80.
Ring segment 100 also includes pads 102, 104, and 112. Pads 102 and 104 are
substantially similar to pads 82 and 122. Pad 112 is substantially similar to
pads 84 and
124.
When ring segments 80, 100, and 120 are joined together, a joint face 28
normal
to inner peripheral face 16 is formed as tab 110 is received by recess 94 and
tab 132 is
received by recess 114. The lengths of tabs 90 and 130 and the receiving
depths of
recesses 96 and 136 are preferably dimensioned so that a gap 24 is formed in
outer
peripheral face 22 when recesses 96 and 136 fully receive tabs 130 and 90,
respectively.
A joint face 26 is also formed. Ring segments 90, 100, and 120 operate in a
substantially
similar way as ring segments 30 and 50.
While the invention has been described with a certain degree of particularity,
many changes may be made in the details of construction and the arrangement of
components without departing from the spirit and scope of this disclosure. The
invention, therefore, is to be limited only by the scope of the attached
claims, including
the full range of equivalency to which each element thereof is entitled.
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