Gear pump for pumping abrasive well fluid

Abstract

A gear pump is configured for pumping abrasive fluids from a well. The gear pump includes an electrical motor that is sealed within a motor housing and submersed with the pump. The gear pump has a drive shaft that rotates a drive member, which in turn rotates a driven gear. The gear pump has intake chamber leading to an intake side of the drive and driven gears and a discharge chamber extending from the discharge side. One of the gears has metal teeth while the other has elastomeric teeth.

1 . A well pump apparatus for pumping abrasive fluids from a well, comprising: 
 a housing assembly for submersion in well fluid in a well;    an electric motor sealed within the housing assembly against the well fluid;    a drive shaft rotated by the motor and located within the housing assembly;    a drive member located within the housing assembly and operatively coupled to the drive shaft for rotation therewith, the drive member having a plurality of lobes spaced around an axis of the drive shaft;    a driven member rotatably mounted in the housing assembly next to the drive member, the driven member having a plurality of lobes that intermesh with the lobes of the drive member;    an intake chamber in the housing assembly leading from an exterior of the housing assembly to an intake side of the drive and driven members for flowing well fluid into contact with the drive and driven members;    a discharge chamber in the housing assembly extending from a discharge side of the drive and driven members to the exterior of the housing assembly for discharging the well fluid passing through the drive and driven members while rotating; and    the lobes of one of the members having metal surfaces, and the lobes of the other member having elastomeric surfaces to reduce wear due to abrasive particles in the well fluid passing through the drive and driven members;.    
   
   
       2 . The apparatus according to  claim 1 , wherein the member having the lobes with elastomeric surfaces comprises an elastomeric sleeve mounted on a metal core.  
   
   
       3 . The apparatus according to  claim 1 , wherein the lobes of the drive and driven members comprise gear teeth.  
   
   
       4 . The apparatus according to  claim 1 , wherein each of the drive and driven members has an axial dimension that is the same, and wherein the housing assembly further comprises: 
 a base plate having a thickness that is the same as the axial dimension of the drive and driven members, the plate having cavities formed therein for defining the intake and discharge chambers.    
   
   
       5 . The apparatus according to  claim 1 , wherein the housing assembly comprises: 
 a motor housing enclosing the motor;    a manifold housing having an inlet for the intake chamber and an outlet for the discharge chamber; and    a base plate sandwiched between the motor housing and the manifold housing, the plate having cavities formed therein for defining the intake and discharge chambers.    
   
   
       6 . The apparatus according to  claim 5 , wherein each of the drive and driven members has an axial dimension that is the same, and wherein the plate has a thickness that is the same as the axial dimension of the drive and driven members.  
   
   
       7 . The apparatus  6 , wherein the plate is releasably clamped between the motor housing and the manifold housing to enable the drive and driven members and the plate to be interchanged with drive and driven members of different axial dimensions and plates of different thicknesses.  
   
   
       8 . The apparatus according to  claim 5 , wherein the plate is formed of a hard, wear-resistant material.  
   
   
       9 . The apparatus according to  claim 1 , wherein the metal surfaces on the lobes of said one of the members comprises a hard, wear resistant material.  
   
   
       10 . A well pump apparatus, comprising: 
 a string of conduit suspended in a well; and    a gear pump having a submersible electric motor, an intake leading to the exterior of the gear pump for drawing well fluid from the well and a discharge coupled to the conduit for pumping the well fluid through the conduit to the surface.    
   
   
       11 . The apparatus according to  claim 9 , wherein the gear pump comprises: 
 a drive member driven by the electric motor and having a plurality of lobes;    a driven member having a plurality of lobes that intermesh with and are driven by the lobes of the drive member; and wherein    the lobes of one of the members are formed of metal and the lobes of the other of the members are formed of an elastomeric material.    
   
   
       12 . The apparatus according to  claim 11 , wherein each of the drive and driven members has an axial dimension that is the same, and wherein the gear pump further comprises: 
 a plate having a uniform thickness that is the same as the axial dimension of the drive and driven members, the plate having cavities formed therein for defining intake and discharge chambers that receive the drive and driven members.    
   
   
       13 . The apparatus according to  claim 9 , wherein the gear pump comprises: 
 a motor housing enclosing the motor;    a manifold housing defining the intake and discharge; and    a base plate of uniform thickness sandwiched between the motor housing and the manifold housing, the plate having cavities formed therein for defining intake and discharge chambers, the plate being interchangeable with plates of different thicknesses.    
   
   
       14 . The apparatus according to  claim 13 , wherein the plate is formed of a hard, wear-resistant material.  
   
   
       15 . A method of pumping well fluid from a well, comprising: 
 suspending a gear pump and submersible electric motor in the well; and    supplying electrical power to the motor to cause the gear pump to draw well fluid therein and pump the well fluid to the surface.    
   
   
       16 . The method according to  claim 15 , further comprising: 
 providing the gear pump with drive and driven members having intermeshing lobes, the drive member being driven by the electric motor; and    wherein the lobes of one of the members are formed of metal and the lobes of the other of the members are formed of an elastomeric material.