Multi-Piece Pressure Operated Rings for a Downhole Pump Plunger

Abstract

A pressure responsive seal ring assembly includes a first and second arcuate-shaped ring segment configured for non-interlocking assembly onto a plunger body. A tab extends beyond a first end of each ring segment and is received by a recessed portion in the first end of the opposing ring segment. The tabs and recessed portions provide a gap in the outer peripheral surface of the assembled ring. A second tab extends beyond a second end of the second ring segment and is received by a recessed portion in the second end of the first ring segment. Pads provide an inter-space effective for allowing fluid flow between the interior peripheral surface and the plunger body. The ring segments expand radially outward with an increase in pressure to provide a seal and retract radially inward with a decrease in pressure. The ring segments, however, remain connected and resist fluid flow therebetween.

Description

REFERENCE TO PENDING APPLICATIONS

This application is not based upon any pending domestic or international patent applications.

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.

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. Pat. 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. Pat. 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 face of the ring is not tapered. Similar to the operation of the U.S. Pat. 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.

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.

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

FIG. 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.

FIG. 2 is an isometric view of the plunger ring in its assembled state.

FIG. 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.

FIG. 4 is a cross-sectional view of the plunger ring taken along section line 4-4 of FIG. 3. An annular groove is provided on the upper surface of the ring segment to facilitate expansion and retraction of the ring segments.

FIG. 5 is a cross-sectional view of the plunger ring taken along section line 5-5 of FIG. 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.

FIG. 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.

FIG. 7 is a front view of the first ring segment.

FIG. 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.

FIG. 9 is a top view of the second ring segment.

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FIG. 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.

FIG. 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.

FIG. 12 is a view of the plunger taken along section line 12-12 of FIG. 11 and shows the assembling of the ring segments in a seal ring groove.

FIG. 13 is a view of the plunger taken along section line 13-13 of FIG. 11 and illustrating the assembled ring. The pads provide an inter-space for fluid flow between the ring and the plunger body.

FIG. 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.

FIG. 15 is an end view of the first ring segment taken along section line 15-15 of FIG. 14.

FIG. 16 is an end view of the first ring segment taken along section line 16-16 of FIG. 14.

FIG. 17 is an end view of the second ring segment taken along section line 17-17 of FIG. 14.

FIG. 18 is an end view of the second ring segment taken along section line 18-18 of FIG. 14.

FIG. 19 is an end view of the third ring segment taken along section line 19-19 of FIG. 14.

FIG. 20 is an end view of the third ring segment taken along section line 19-19 of FIG. 14.

FIGS. 21 to 23 illustrate the order of assembly of the three-piece plunger ring onto a plunger body.

FIG. 24 is a view of the assembled three-piece plunger ring.

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:

10	Plunger ring	52	Pad	108	Second end
	assembly	54	Pad	110	Extension
12	Annular groove	56	First end	112	Pad
14	Inner side wall	58	Second end	114	Recess
16	Inner face	60	Extension	120	Ring segment
18	Outer wall	62	Pad	122	Pad
20	Outer face	64	Extension	124	Pad
22	Lower face	66	Recess	126	First end
24	Gap	80	Ring segment	128	Second end
26	Joint	82	Pad	130	Extension
28	Joint	84	Pad	132	Extension
30	Ring segment	86	First end	134	Pad
32	Pad	88	Second end	136	Recess
34	Pad	90	Extension	150	Tubular plunger
36	First end	92	Pad	152	Working barrel
38	Second end	94	Recess	154	Central opening
40	Extension	96	Recess	156	Wall
42	Pad	100	Ring segment	158	Ring groove
44	Recess	102	Pad	160	Spacer flange
46	Recess	104	Pad	162	Circumferential
50	Ring segment	106	First end		space
				164	Inter-space

Referring to the drawings and first to FIGS. 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 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 FIGS. 4-5 & 7-8. In a preferred embodiment, 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 FIG. 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 FIGS. 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 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 FIG. 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 FIGS. 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 FIG. 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.

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 FIGS. 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. 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 FIGS. 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.

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.

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.

Claims

1. A pressure responsive seal ring assembly for use in a downhole submerged pump assembly, the pump assembly including a plunger with a metallic cylinder and at least one seal ring groove in the cylinder for receiving a seal ring, the seal ring comprising:

a first and second arcuate-shaped ring segment, said first and second ring segments having a first and second end, said first and second ends having an angular distance therebetween of less than 180°;

a first tab that extends beyond said first end of each of said ring segments, said first tab and said second end of each of said ring segments having an angular distance therebetween of greater than 180°;

a first recessed portion in said first end of each of said ring segments, said first recessed portion in each of said ring segments being substantially co-planer with said first tab of an opposing said ring segment, said recessed portion capable of receiving said opposing first tab;

a second tab that extends beyond said second end of said second ring segment, said second tab and said first end having an angular distance therebetween of greater than 180°; and

a second recessed portion in said second end of said first ring segment, said second recessed portion being substantially co-planar with said second tab and capable of receiving said second tab.

wherein said ring segments connect to one another in a non-locking manner so that under pressure said ring segments expand radially outward and resist fluid flow therebetween.

2. A seal ring assembly according to claim 1 further comprising at least one raised pad located on a portion of an inner peripheral surface of each of said first and second ring segments, said pad providing an effective inter-space for a fluid flow between said inner peripheral surface and the metallic cylinder.

3. A seal ring assembly according to claim 2 further comprising at least one second raised pad located on an inner peripheral surface of said first tab.

4. A seal ring assembly according to claim 1 further comprising a gap in an outer periphery of said seal ring when said seal ring is in a retracted position, said gap formed by said first tab being received by opposing said recessed portion.

5. A seal ring assembly according to claim 1 wherein an outside diameter of said seal ring in a retracted position is slightly less than an inside diameter of a working barrel in communication with the plunger.

6. A seal ring assembly according to claim 1 further comprising said seal ring having an annular groove in an upper surface of each of said ring segments.

7. A pressure responsive seal ring assembly for use in a downhole submerged pump assembly, the pump assembly including a plunger with a metallic cylinder and at least one seal ring groove in the cylinder for receiving a seal ring, the seal ring comprising:

a plurality of arcuate-shaped ring segments, each of said ring segments having a first and second end;

at least one tab located on each of said ring segments and extending beyond one of said first and second ends; and

at least one recessed portion in one of said first and second ends, said recessed portion being substantially co-planar with said tab of an opposing said ring segment and capable of receiving said opposing tab;

wherein said ring segments connect to one another in a non-locking manner so that under pressure said ring segments expand radially outward and resist fluid flow therebetween.

8. A seal ring assembly according to claim 7 further comprising at least one pad located on a portion of an inner peripheral surface of at least one of said plurality of ring segments, said pad providing an effective inter-space for a fluid flow between said inner peripheral surface and the metallic cylinder.

9. A seal ring assembly according to claim 8 further comprising at least one second raised pad located on an inner peripheral surface of said at least one tab.

10. A seal ring assembly according to claim 7 further comprising a gap in an outer periphery of said seal ring when said seal ring is in a retracted position, said gap formed by two of said tabs being received by opposing said recessed portions.

11. A seal ring assembly according to claim 7 wherein said accurate-shaped ring segments are two in number.

12. A seal ring assembly according to claim 13 further comprising said first and second ends having an angular distance therebetween of less than 180°.

13. A seal ring assembly according to claim 7 wherein said arcuate-shaped ring segments are three in number.

14. A seal ring assembly according to claim 14 further comprising said first and second ends of at least two rings having an angular distance therebetween of less than 120°.

15. A seal ring assembly according to claim 7 wherein an outside diameter of said seal ring in a retracted position is slightly less than an inside diameter of a working barrel in communication with the plunger.

16. A seal ring assembly according to claim 7 further comprising said seal ring having an annular groove in an upper surface of each of said ring segments.