Electric submersible pump configuration

Abstract

A housing-less wellbore pump assembly is described. The pump assembly includes multiple pump stages connected end-to-end axially to pump well fluid in an uphole direction. Each pump stage includes a rotating impeller to rotate to provide kinetic energy to flow fluid through the wellbore pump assembly and a stationary diffuser within which the rotating impeller is positioned. The stationary diffuser converts the kinetic energy received from the rotating impeller to head to flow the fluid through the wellbore pump assembly. The stationary diffuser includes an uphole threaded end and a downhole threaded end to threadedly couple with another, uphole-positioned pump stage and with another, downhole-positioned pump stage, respectively. Threads of the uphole threaded end and the downhole threaded end are formed in directions opposite to a rotational direction of the impeller.

What is claimed is: 
     
         1 . A housing-less wellbore pump assembly comprising:
 a plurality of pump stages connected end-to-end axially and configured to pump well fluid in an uphole direction, each pump stage comprising:
 a rotating impeller configured to rotate to provide kinetic energy to flow fluid through the wellbore pump assembly; and 
 a stationary diffuser within which the rotating impeller is positioned, the stationary diffuser configured to convert the kinetic energy received from the rotating impeller to head to flow the fluid through the wellbore pump assembly, the stationary diffuser comprising an uphole threaded end and a downhole threaded end configured to threadedly couple with another, uphole-positioned pump stage and with another, downhole-positioned pump stage, respectively, threads of the uphole threaded end and the downhole threaded end formed in directions opposite to a rotational direction of the impeller. 
   
     
     
         2 . The pump assembly of  claim 1 , wherein the threads of the uphole threaded end are formed on an outer surface of the diffuser, and wherein the threads of the downhole threaded end are formed on an inner surface of the diffuser. 
     
     
         3 . The pump assembly of  claim 1 , wherein the threads of the uphole threaded end are formed on an inner surface of the diffuser, and wherein the threads of the downhole threaded end are formed on an outer surface of the diffuser. 
     
     
         4 . The pump assembly of  claim 3 , further comprising:
 a first seal positioned between the uphole threaded end and the downhole threaded end of the other, uphole-positioned pump stage; and   a second seal positioned between the downhole threaded end and the uphole threaded end of the other, downhole-positioned pump stage.   
     
     
         5 . The pump assembly of  claim 1 , further comprising:
 a pump base comprising a threaded end threadedly coupled to a downhole threaded end of a downhole-most pump stage, threads of the threaded end of the pump base and the downhole threaded end of the downhole-most pump stage formed in directions opposite to the rotational direction of the impeller; and   a seal positioned between the threaded end of the pump base and the downhole threaded end of the downhole-most pump stage.   
     
     
         6 . The pump assembly of  claim 5 , wherein the downhole-most pump stage comprises a diffuser spacer comprising threaded ends to threadedly couple to the threaded end of the pump base and the downhole threaded end of the downhole-most pump stage, wherein threads of the diffuser spacer formed in directions opposite to the rotational direction of the impeller. 
     
     
         7 . The pump assembly of  claim 1 , further comprising:
 a pump head comprising a threaded end threadedly coupled to an uphole threaded end of an uphole-most pump stage, threads of the threaded end of the pump head and the uphole threaded end of the uphole-most pump stage formed in directions opposite to the rotational direction of the impeller; and   a seal positioned between the threaded end of the pump head and the uphole threaded end of the uphole-most pump stage.   
     
     
         8 . The pump assembly of  claim 1 , wherein the plurality of pump stages are threadedly connected end-to-end axially without an outer housing. 
     
     
         9 . A housing-less wellbore pump assembly comprising:
 a pump base comprising a threaded end; and   a pump stage comprising:
 a rotating impeller configured to rotate to provide kinetic energy to flow fluid through the pump stage and the pump base in an uphole direction through a wellbore; and 
 a stationary diffuser within which the rotating impeller is positioned, the diffuser configured to convert the kinetic energy received from the rotating impeller to head to flow the fluid through the pump stage, the diffuser comprising a downhole threaded end connected with the threaded end of the pump base by a threaded coupling, threads of the threaded ends of the diffuser and the pump base formed in directions opposite to a rotational direction of the impeller. 
   
     
     
         10 . The pump assembly of  claim 9 , further comprising a diffuser spacer positioned between the diffuser and the pump base, the diffuser spacer comprising threaded ends connected with the threaded end of the pump base and the downhole threaded end of the diffuser by respective threaded couplings, threads of the threaded ends of the diffuser spacer, pump base, and diffuser formed in directions opposite to the rotational direction of the impeller. 
     
     
         11 . The pump assembly of  claim 10 , wherein the threaded coupling between one of the threaded ends of the diffuser spacer and the threaded end of the pump base comprises a seal configured to block fluid flowing through the pump base and the pump stage from leaking outside the pump stage. 
     
     
         12 . The pump assembly of  claim 10 , wherein the threaded coupling between the other of the threaded ends of the diffuser spacer and the downhole threaded end of the diffuser comprises a seal configured to block fluid flowing through the pump base and the pump stage from leaking outside the pump stage. 
     
     
         13 . The pump assembly of  claim 9 , wherein the pump stage is a first pump stage, the impeller is a first impeller, the diffuser is a first diffuser, the threaded coupling is a first threaded coupling wherein the pump assembly further comprises a second pump stage uphole of the first pump stage, the second pump stage comprising:
 a second rotating impeller configured to rotate to provide kinetic energy to flow the fluid received from the first pump stage through the second pump stage in the uphole direction; and   a second stationary diffuser within which the second rotating impeller is positioned, the second diffuser configured to convert the kinetic energy received from the second impeller to head to flow the fluid through the second pump stage, the second diffuser comprising a downhole threaded end connected with an uphole threaded end of the first diffuser by a second threaded coupling, threads of the threaded ends of the first and second diffusers formed in directions opposite to a rotational direction of the impellers.   
     
     
         14 . The pump assembly of  claim 13 , further comprising a pump head comprising a threaded end, wherein an uphole threaded end of the second diffuser connected with the threaded end of the pump head by a third threaded coupling, threads of the threaded ends of the second diffuser and the pump head formed in directions opposite to the rotational direction of the impellers. 
     
     
         15 . The pump assembly of  claim 14 , wherein the threaded coupling between the uphole end of the second diffuser and the threaded end of the pump head comprises a seal configured to block fluid flowing through the pump head and the second pump stage from leaking outside the second pump stage.