High temperature motor seal for artificial lift system

Abstract

A thermal compensator for a motor seal, includes: a guide tube for receiving a shaft of the motor seal; a metallic bag disposed around the guide tube and having an expansion profile formed in at least a portion thereof to accommodate radial and circumferential expansion of the metallic bag; a pair of flanges attached to opposite ends of the metallic bag; and a pair of adapters fastened to the respective flanges and receiving respective ends of the guide tube.

1 . A thermal compensator for a motor seal, comprising:
 a guide tube for receiving a shaft of the motor seal;   a bag mandrel disposed around the guide tube;   one or more metallic bags attached to and disposed around the bag mandrel and having an expansion profile to accommodate at least one of: radial, circumferential, and tangential expansion thereof;   a pair of flanges attached to opposite ends of the bag mandrel; and   a pair of adapters fastened to the respective flanges and receiving respective ends of the guide tube.   
     
     
         2 . The thermal compensator of  claim 1 , wherein:
 the bag mandrel is cylindrical,   the thermal compensator includes two or more of the bags,   each bag is a cylindrical segment having an outer wall, side walls, and upper and lower walls, and   the bags are spaced around the bag mandrel with a gap between adjacent bags to accommodate the expansion thereof.   
     
     
         3 . The thermal compensator of  claim 1 , wherein:
 the bag mandrel is polygonal,   the thermal compensator includes a bag attached to each side of the bag mandrel, and   each bag is box shaped.   
     
     
         4 . The thermal compensator of  claim 3 , wherein each bag has the expansion profile formed only on side, upper, and lower walls thereof for radial expansion only. 
     
     
         5 . The thermal compensator of  claim 3 , wherein each bag has the expansion profile formed only on outer, upper, and lower walls thereof for tangential expansion only. 
     
     
         6 . A thermal compensator for a motor seal, comprising:
 a guide tube for receiving a shaft;   a bag mandrel disposed around the guide tube;   a plurality of metallic bags attached to the bag mandrel, wherein each of the plurality of metallic bags includes an expansion profile, the plurality of metallic bags are spaced around the bag mandrel having a gap formed between adjacent bags to accommodate expansion and contraction, the bag mandrel has a plurality of ports formed through a mandrel wall for lubricant communication with the plurality of metallic bags.   
     
     
         7 . The thermal compensation of  claim 6 , wherein the expansion profile is one of a stepped expansion profile, a convoluted expansion profile, a corrugated expansion profile, a pleated expansion profile, or a combination thereof. 
     
     
         8 . The thermal compensation of  claim 6 , wherein each metallic bag is a cylindrical section having an outer wall, sidewalls, an upper wall, and a lower wall. 
     
     
         9 . The thermal compensation of  claim 8 , wherein each of the outer wall, sidewall, upper wall, and lower wall has the expansion profile. 
     
     
         10 . The thermal compensation of  claim 6 , wherein the plurality of metallic bags are attached to the bag metal by welding. 
     
     
         11 . The thermal compensation of  claim 6 , wherein the plurality of metallic bags are formed from aluminum, copper, tin, lead, brass, bronze, low carbon steel, high strength low alloy steel, stainless steel, gold, silver, titanium, nickel, or alloys based on the metals thereof. 
     
     
         12 . The thermal compensation of  claim 6 , wherein each of the plurality of metallic bag is a box shaped having an outer wall, side walls, an upper wall, and a lower wall. 
     
     
         13 . The thermal compensation of  claim 12 , wherein the expansion profile is formed only on the sidewalls, upper wall and lower wall for radial expansion only. 
     
     
         14 . The thermal compensation of  claim 12 , wherein the expansion profiled is formed only on the outer wall, upper wall and lower wall for tangential expansion only. 
     
     
         15 . The thermal compensation of  claim 6 , wherein the bag mandrel is cylindrical. 
     
     
         16 . The thermal compensation of  claim 6 , wherein the bag mandrel is polygonal having a metallic bag on each side. 
     
     
         17 . A method for pumping production fluid from a wellbore, comprising:
 deploying a downhole assembly of an artificial lift system into the wellbore, the downhole assembly comprising an electric motor, a pump, and a motor seal disposed between the motor and the pump, wherein the motor seal includes a thermal compensator having a plurality of metallic bags with an expansion profile; and   operating the electric motor, thereby driving the pump and lifting production fluid from the wellbore to surface while allowing the plurality of metallic bags to expand and contract to accommodate thermal expansion of the motor oil.   
     
     
         18 . The method of  claim 17 , wherein the plurality of metallic bags expand and contract along a radial direction only. 
     
     
         19 . The method of  claim 17 , wherein the plurality of metallic bags expand and contract along a tangential direction only. 
     
     
         20 . The method of  claim 17 , wherein the plurality of metallic bags expand and contract expand and contract radially and tangentially.