High pressure water injection pump system

Abstract

The invention provides a high pressure water injection pump system, comprising at least two water injection pump units connected in series, each pump unit comprising a motor in a motor compartment operatively connected to drive a pump in a pump compartment, distinctive in that at least the pump units following the first pump comprises a choke compartment arranged between the pump and motor compartments, a leakage seal arranged between the pump and choke compartment, the choke compartment having an outlet; and the motor compartment of at least the pump units following the first pump unit is dimensioned according to a lower pressure class than the operatively connected pump compartment.

1 . A high pressure water injection pump system, comprising:
 at least two water injection pump units connected in series, each pump unit comprising:   a motor in a motor compartment operatively connected to drive a pump in a pump compartment;   wherein at least the pump units following a first pump of the at least two water injection pumps comprises:   a choke compartment arranged between the pump compartment and the motor compartments;   a leakage seal arranged between the pump compartment and the choke compartment, the choke compartment having an outlet; and   wherein the motor compartment of at least the pump units following the first pump unit is dimensioned according to a lower pressure class than an operatively connected pump compartment.   
     
     
         2 . The high pressure water injection pump system according to  claim 1 , wherein for the pump units following the first pump unit, the motor compartment pressure housings are dimensioned for equal pressure as the pressure housing of the first pump. 
     
     
         3 . The high pressure water injection pump system according to  claim 1 , wherein all motor compartment pressure housings are dimensioned for equal pressure class. 
     
     
         4 . The high pressure water injection pump system according to  claim 1 , wherein each choke compartment is connected to a leakage line connected to the inlet line to the first pump. 
     
     
         5 . The high pressure water injection pump system according to  claim 1 , wherein a leakage seal is arranged between the pump compartment housing and a choke compartment, the choke compartment is for each pump unit arranged between the pump and motor compartments and each choke compartment is connected to a leakage line connected to the inlet line to the first pump. 
     
     
         6 . The high pressure water injection pump system according to  claim 4 , wherein each choke compartment includes a choke seal in the partition wall toward the pump compartment, the choke seal is a labyrinth seal or any type of mechanical seal having a choke or leakage effect, such as a spring loaded mechanical seal of which the spring adjusts the leakage opening, preferably a controlled or adjustable choke effect, and a fluid tight mechanical seal is arranged in the partition wall between each choke compartment and motor compartment. 
     
     
         7 . The high pressure water injection pump system according to  claim 1 , wherein seawater is used as a motor cooling medium, the seawater is provided by at least one separate seawater cooling pump arranged to pump the seawater through the motor compartments, preferably the seawater pump is arranged as seawater pump impellers on the motor shaft. 
     
     
         8 . The high pressure water injection pump system according to  claim 1 , wherein injection water is used as a motor cooling medium, provided by the injection water for cooling leaking through a choke or leakage seal arranged in a partition wall between the pump and motor compartments, said seal can be a labyrinth seal or any type of mechanical seal having a choke or leakage effect such as a spring loaded seal, preferably the seal leakage rate is proportional to the motor cooling demand. 
     
     
         9 . A method for arranging a high pressure water injection pump system, the pump system comprising:
 at least two water injection pump units connected in series, each pump unit comprising:   a motor in a motor compartment operatively connected to drive a pump in a pump compartment,   the method comprising:   arranging for at least the pump units following the first pump a choke compartment between the pump and motor compartments, a leakage seal between the pump and choke compartment, and an an outlet from the choke compartments; and   dimensioning the motor compartment of at least the pump units following the first pump unit according to a lower pressure class than the operatively connected pump compartment, more preferably the motor compartment pressure housings of the pump units following the first pump unit are dimensioned for equal pressure as the pressure housing of the first pump, most preferably all motor compartment pressure housings are dimensioned for equal pressure class.   
     
     
         10 . Use of the high pressure water injection pump system according to  claim 1 , for injecting water at high pressure into a subsea underground reservoir. 
     
     
         11 . A high pressure water injection pump system, comprising:
 at least two water injection pump units connected in series, each pump unit comprising:   a motor in a motor compartment operatively connected to drive a pump in a pump compartment,   a leakage seal arranged between the pump and motor compartments, the motor compartment having an outlet and being cooled by the leaked in water and optionally by introduced seawater, and preferably the motor compartment of at least the pump units following the first pump unit is dimensioned according to a lower pressure class than the operatively connected pump compartment.