Method of controlling an electric submersible pump

Abstract

A method of controlling an electric submersible pump, comprising: a) monitoring the pressure at the suction and discharge of the pump; b) calculating the pressure difference between the discharge and suction pressure; and c) controlling the pump to maintain a constant pressure difference between the discharge and suction pressure.

1 . A method of controlling an electric submersible pump, comprising:
 a. monitoring the pressure at the suction and discharge of the pump;   b. calculating the pressure difference between the discharge and suction pressure; and   c. controlling the pump to maintain a constant pressure difference between the discharge and suction pressure.   
     
     
         2 . The method of  claim 1  wherein the electric submersible pump is located in a subsea caisson below the seafloor. 
     
     
         3 . The method of  claim 1  wherein the electric submersible pump comprises a pump and a shroud. 
     
     
         4 . A method of starting up an electric submersible pump during start up, comprising:
 a. starting the pump on constant boost control, comprising:
 i. monitoring the pressure at the suction and discharge of the pump; 
 ii. calculating the pressure difference between the discharge and suction pressure; and 
 iii. controlling the pump to maintain a constant pressure difference between the discharge and suction pressure; and 
   b. switching the constant boost control to pressure control, comprising:
 i. monitoring the pressure at the caisson top; and 
 ii. controlling the pump to maintain a constant pressure at the caisson top. 
   
     
     
         5 . The method of  claim 4  wherein the switching the constant boost control to pressure control is carried out by operator intervention. 
     
     
         6 . A method of controlling an electric submersible pump during operation, comprising:
 a. monitoring the pressure at the caisson top;   b. switching the pressure control to constant boost control when the pressure goes outside of a determined operational pressure range during operation; and   c. switching the constant boost control to pressure control when the pressure has stabilized inside of the determined operational pressure range.   
     
     
         7 . The method of  claim 6  wherein the switching the constant boost control to pressure control is carried out by operator intervention. 
     
     
         8 . The method of  claim 6  further comprising carrying out steps b) and c) repeatedly as the pressure goes outside of the range and then is stabilized inside of the range.