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[0001]This application is not based upon any pending domestic or international patent applications.FIELD OF THE INVENTION[0002]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[0003]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.[00...

AI Technical Summary

Benefits of technology

"The invention is a seal ring assembly for use in a downhole submerged pump assembly. The seal ring is made of a metallic cylinder with at least one seal ring groove for receiving a seal ring. The seal ring has two arcuate-shaped ring segments that interconnect in a non-locking manner. Each ring segment has a first and second end with an angular distance between them of less than 180°. A first tab extends beyond the first end of each ring segment and a second tab extends beyond the second end of the second ring segment. The seal ring expands radially outward and resists fluid flow therebetween under pressure. The seal ring also has a raised pad on its inner peripheral surface for fluid flow and an annular groove in its upper surface. The seal ring can have three arcuate-shaped ring segments with a tab-and-recess combination that interconnect in a non-locking manner. The technical effect of this invention is to provide a reliable seal for fluid flow between the plunger and the working barrel in a downhole submerged pump assembly."

Problems solved by technology

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.

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.

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.

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.

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