Downhole pumps with outside pressure balancing and sand separation and isolation

Abstract

The present disclosure relates to a downhole pump designed to include a sand separation unit. In one implementation, the downhole pump comprises a barrel having a first valve for controlling fluid flow into the barrel. The first valve includes an interior cavity with a first surface. The downhole pump further includes a plunger housed within the interior cavity of the barrel. The plunger comprises a wiper-plunger having a first circumference to which one or more resilient seals are coupled. The one or more resilient seals seal a first boundary between the first circumference of the wiper- plunger and a first portion of the first surface associated with the barrel. The plunger further comprises a sand separation unit coupled to the wiper-plunger at a first side. The sand separation unit forms a balancing chamber that minimizes a pressure differential across the one or more resilient seals. The sand separation unit uses centrifugal force to separate particulate matter from fluid during a first motion of the wiper-plunger relative to the first portion of the first surface associated with the barrel. The plunger further comprises a plunger-assembly coupled to the sand separation unit at a second side. The plunger-assembly has a second valve that controls fluid flow into the plunger-assembly via a third side from the interior cavity of the barrel. Additionally, the plunger includes a second boundary between a second circumference of the plunger-assembly and a second portion of the first surface associated with the barrel. The second boundary is fillable by slippage fluid within the barrel to create a fluid seal at the second boundary.

What is claimed is: 
     
         1 . A downhole pump comprising:
 a barrel having a first valve for controlling fluid flow into the barrel, the barrel including an interior cavity with a first surface;   a plunger housed within the interior cavity of the barrel, the plunger comprising:
 a wiper-plunger having a first circumference to which one or more resilient seals are coupled, the one or more resilient seals sealing a first boundary between the first circumference of the wiper-plunger and a first portion of the first surface associated with the barrel; 
 a sand separation unit coupled to the wiper-plunger at a first side, the sand separation unit forming a balancing chamber that minimizes a pressure differential across the one or more resilient seals, the sand separation unit using centrifugal force to separate particulate matter from fluid during a first motion of the wiper-plunger relative to the first portion of the first surface associated with the barrel; 
 a plunger-assembly coupled to the sand separation unit at a second side, the plunger-assembly having a second valve controlling fluid flow into the plunger-assembly via a third side from the interior cavity of the barrel; 
 a second boundary between a second circumference of the plunger- assembly and a second portion of the first surface associated with the barrel, the second boundary being fillable by slippage fluid within the barrel to create a fluid seal at the second boundary. 
   
     
     
         2 . The downhole pump of  claim 1 , wherein the one or more resilient seals are elastomeric and include at least a fiber component. 
     
     
         3 . The downhole pump of  claim 1 , further comprising one or more openings that ensure that a first portion of the wiper-plunger has a first pressure that is substantially equivalent to a second pressure associated with the balancing chamber to minimize wear on the one or more resilient seals.