1. Field of the Invention
Embodiments of the invention relate to a wiper assembly that prevents most or all debris, such as sand particles, from entering an operating region of a pump.
2. Description of the Related Art
To obtain fluids from an earth formation, a wellbore is drilled into the earth to intersect an area of interest within the formation. Upon reaching the area of interest within the formation, artificial lift means is often necessary to carry production fluid (e.g. hydrocarbon fluid) from the area of interest within the wellbore to the surface of the wellbore. Some artificially lifted wells are equipped with sucker rod lifting systems.
Sucker rod lifting systems generally include a surface drive unit, a sucker rod string, and a downhole positive displacement pump. The pump generally includes an outer barrel and an operating member, such as a plunger axially movable within the barrel to lift fluid to the surface. The sucker rod string generally comprises several rods connected together but may be one continuous rod, and is the primary link between the drive unit at the surface and the pump plunger. Reciprocating pumping action moves a traveling valve on the pump plunger, loading it on the down-stroke and lifting fluid to the surface on the up-stroke.
One problem associated with sucker rod lifting systems is wear within the annular region between the plunger and the barrel due to wellbore debris, such as sand. Since the annular region is typically about 0.002 inches to about 0.005 inches (per side), sand particles of various size enter the region and act as an abrasive, which quickly forms “grooves” in both the barrel and the plunger sliding surfaces. Such wear significantly diminishes the life of the barrel and the plunger, and can lead to costly repair and frequent maintenance.
Therefore, there is a need for an assembly to prevent debris from entering an operating region of a pump.