Reciprocating rod pump for sandy fluids

摘要

A downhole pump has a barrel and a plunger movably disposed therein. The gap between the barrel and plunger has first and second seals. The barrel and plunger each have a one-way valve restricting fluid passage out of it. A filter or screen is disposed on the plunger between the first and second seals. In a downstroke, fluid and particulate in the barrel transfers into the plunger. In an upstroke, fluid and particulate in the plunger lifts uphole. At the same time, a volume in the barrel fills with fluid and particulate. During either stroke, the first seal prevents particulate uphole of the plunger from passing into the gap. The filter or screen, however, prevents at least some particulate (i.e., most or larger particulate) inside the plunger from passing out of the plunger with fluid flowing into the gap between the first and second seals.

主权项

1. A downhole pump, comprising
a barrel having a first one-way valve restricting fluid passage out of the barrel; a plunger reciprocally disposed in the barrel and having first and second seals with the plunger and the barrel, the plunger having a second one-way valve restricting fluid passage out of an interior of the plunger and into a variable volume defined between the first and second one-way valves; and a screen disposed on the plunger between the first and second seals and separating the interior of the plunger from a gap between the plunger and the barrel, the screen permitting fluid passage between the interior and the gap and restricting particulate in the interior from passing into the gap, the screen comprising profiled wire forming a plurality of slotted openings, narrower portions of the slotted openings facing the interior of the plunger, where in a first stroke moving the barrel and the plunger relative to one another in a first direction, the variable volume decreases, the first one-way valve closes, and the second one-way valve opens, and where in the first stroke, fluid entering the interior of the plunger from the variable volume through the second one-way valve clears particulate adjacent a face of the wire on the screen exposed to the interior of the plunger.