Pump Motor Protector with Redundant Shaft Seal

Abstract

An electric submersible pump device having a motor part, a pump part, and a protector part. The protector part includes redundant shaft seal parts.

1 . An electric submersible pump device, comprising:
 an electric submersible motor part that produces torque having coupled thereto a drive shaft that transmits the torque, the drive shaft extending in an axial direction from the motor part;   a protector part coupled with the motor part, the drive shaft extending into the protector part, the protector part comprising a tubular shaped casing extending in the axial direction;   a shaft tube surrounding a portion of the drive shaft thereby defining a space between the outer surface of the shaft and an interior of the shaft tube;   an opening in the shaft tube connecting the interior of the shaft tube with an exterior of the shaft tube; and   a first compensating element connected with the opening, the first compensating element being an expandable and contractible vessel defining a volume that is correspondingly expandable and contractible.   
     
     
         2 . The electric submersible pump device of  claim 1 , comprising:
 a motor compensating element in fluid connection with the motor part, the motor compensating element being an expandable and contractible vessel defining a volume that is correspondingly expandable and contractible.   
     
     
         3 . The electric submersible pump device of  claim 1 , comprising:
 a first shaft seal part located inside the volume, and   a second shaft seal part located inside the volume,   the shaft tube coupled with and extending between the first shaft seal part and the second shaft seal part.   
     
     
         4 . The electric submersible pump device of  claim 1 , wherein the first compensating element is a metal bellows. 
     
     
         5 . The electric submersible pump device of  claim 1 , wherein the first compensating element is a piston/cylinder. 
     
     
         6 . The electric submersible pump device of  claim 1 , wherein the first compensating element is an elastomeric bladder. 
     
     
         7 . The electric submersible pump device of  claim 1 , wherein the first compensating element is non-coaxial with the shaft. 
     
     
         8 . The electric submersible pump device of  claim 1 , wherein the first compensating element is coaxial with the shaft. 
     
     
         9 . The electric submersible pump device of  claim 2 , wherein the motor compensating element is a metal bellows. 
     
     
         10 . The electric submersible pump device of  claim 1 , comprising a labyrinth protector seal. 
     
     
         11 . The electric submersible pump device of  claim 1 , comprising a pump part coupled with the drive shaft. 
     
     
         12 . The electric submersible pump device of  claim 1 , comprising a relief valve connecting between the volume inside the casing with a volume outside the casing. 
     
     
         13 . An electric submersible pump device, comprising:
 an electric submersible motor part that produces torque, the electric submersible motor part having coupled thereto a drive shaft that transmits the torque, the drive shaft extending in an axial direction from the motor part;   a pump part rotationally coupled with the drive shaft;   a protector part coupled between the motor part and the pump part, the drive shaft extending into the protector part, the protector part comprising:   a tubular shaped casing extending in an axial direction having an inner surface defining an inner volume;   a first shaft seal part located inside the volume and dividing the volume into an upper volume and a lower volume; the first shaft seal part comprising:
 a first relief valve biased to only allow flow away from the motor part; 
   a second shaft seal part located inside the volume and dividing the upper volume, the second shaft seal part comprising;
 a second relief valve biased to only allow flow away from the first shaft seal part and the motor part; 
 a first compensating element compensating pressure across the second shaft seal divide, the first compensating element being an expandable and contractible vessel defining an interior volume that is correspondingly expandable and contractible; and 
   at least one motor compensating element in fluid communication with the motor part to compensate for thermal expansion and contraction of fluid in the motor part;   wherein during thermal fluid contraction a volume of fluid between the first shaft seal part and the second shaft seal part is prevented from fluidly flowing back into the motor part and contributing more than half of the contraction compensation of fluid in the motor part.   
     
     
         14 . The electric submersible pump device of  claim 13 , comprising a third shaft seal part comprising a second compensating element
 compensating pressure across the third shaft seal part divide, the second compensating element being an expandable and contractible vessel defining an interior volume that is correspondingly expandable and contractible.   
     
     
         15 . The electric submersible pump device of  claim 14 , wherein the maximum volume of the second compensating element is greater than the maximum volume of the first compensating element. 
     
     
         16 . The electric submersible pump device of  claim 13 , comprising a third shaft seal part comprising a second and third compensating element compensating pressure across the third shaft seal part divide, the second and third compensating elements each being expandable and contractible vessels defining interior volumes that are correspondingly expandable and contractible. 
     
     
         17 . The electric submersible pump device of  claim 16 , the third shaft seal part comprising:
 a third relief valve biased to only allow flow away from the first shaft seal part and the motor part.   
     
     
         18 . The electric submersible pump device of  claim 13 , comprising at least one motor compensating element fluidly connected with the motor part, the at least one motor compensating element being an expandable and contractible vessel defining an interior volume that is correspondingly expandable and contractible; and
 wherein the maximum volume of the at least one motor compensating element is greater than a maximum volume of the first compensating element.   
     
     
         19 . The electric submersible pump device of  claim 18 , wherein the maximum volume of the at least one motor compensating element is at least 1/10 the volume of the motor fluid that can be contained in the motor part. 
     
     
         20 . The electric submersible pump device of  claim 18 , wherein the maximum volume of the at least one motor compensating element is at least 5 times larger than the maximum combined volume of the first compensating element and the second compensating element. 
     
     
         21 . The electric submersible pump device of  claim 13 , wherein the maximum volume of the at least one motor compensating element is at least 10 times greater than the maximum volume of the first compensating element. 
     
     
         22 . The electric submersible pump device of  claim 13 , wherein the at least one motor compensating element is a bellows and the first compensating element is a bellows. 
     
     
         23 . The electric submersible pump device of  claim 13 , comprising at least one filter located in a flow path of fluid. 
     
     
         24 . A method of self regulating motor fluid volume in an electric submersible pump device having an electric submersible motor part that produces torque, the electric submersible motor part having coupled thereto a drive shaft that transmits the torque, the drive shaft extending in an axial direction from the motor part;
 a pump part rotationally coupled with the drive shaft;   a protector part coupled between the motor part and the pump part, the drive shaft extending into the protector part, the protector part comprising:   a tubular shaped casing extending in an axial direction having an inner surface defining an inner volume;   a first shaft seal part located inside the volume and dividing the volume into an upper volume and a lower volume; the first shaft seal part comprising:
 a first relief valve biased to only allow flow away from the motor part; 
   a second shaft seal part located inside the volume and dividing the upper volume, the second shaft seal part comprising;
 a second relief valve biased to only allow flow away from the first shaft seal part and the motor part; 
 a first compensating element compensating pressure across the second shaft seal divide, the first compensating element being an expandable and contractible vessel defining an interior volume that is correspondingly expandable and contractible; and 
   at least one motor compensating element in fluid communication with the motor part to compensate for thermal expansion and contraction of fluid in the motor part;   the method comprising:   filling the motor part with motor fluid;   running the motor and increasing temperature of the motor fluid and inducing thermal expansion of the motor fluid into the at least one motor compensating element beyond the maximum capacity of the at least one motor compensating element and forcing fluid through the first relief valve into the upper volume;   subsequently lowering the temperature of the motor part and the motor fluid remaining in the motor part to induce thermal contraction of the motor fluid in the motor part and compensating for the thermal contraction by contracting the at least one motor compensation element; and   preventing return of the motor fluid that traveled through the first biased relief valve during contraction compensation.