Method for extending the life of thin walled tubing and austempered weld stress relieved thin walled tubing

Abstract

The present invention is directed to a method of extending the life of thin walled tubing by austempering the tubing in a controlled continuous run process involving heating, quenching, and cooling the tubing pursuant to predetermined process parameters. The invention is also directed to a process for austempering tubing having a welded seam and for relieving residual stress in the weld. The invention is further directed to the product of the above processes as well as an austermpered weld stress relieved thin walled tubing and such tubing in combination with other apparatus with which it is suitable for use in the production of hydrocarbons.

1 . A method for austempering thin walled tubing, comprising: 
 a. heating a section of metallic tubing having a wall thickness of less than 0.25 inches to a high temperature in the range of 1300-1600° F. in a heater;    b. moving the section of metallic tubing from the heater to a low temperature reservoir as part of a continuous run process;    c. quenching the section of metallic tubing in the low temperature reservoir to reduce the temperature of the section of metallic tubing to a first low temperature in the range of 500-1000° F. in a time period of less than 3 seconds;    d. allowing the section of metallic tubing to transform to bainite;    e. moving the section of metallic tubing transformed into bainite out of the low temperature reservoir as part of the continuous run process; and    f. cooling the section of metallic tubing to a second low temperature below 100° F.    
   
   
       2 . The method of  claim 1 , wherein the heater used for heating is an induction heater.  
   
   
       3 . The method of  claim 1 , wherein the low temperature reservoir used for quenching is a molten salt bath.  
   
   
       4 . The method of  claim 1 , wherein the moving is accomplished in part by using rollers.  
   
   
       5 . The method of  claim 1 , wherein the cooling is accomplished by forced convection.  
   
   
       6 . The method of  claim 1 , wherein the section of metallic tubing comprises a steel alloy with a carbon content greater than or equal to 0.25 and less than or equal to 0.45.  
   
   
       7 . The method of  claim 6 , wherein the section of metallic tubing comprises 4130 alloy steel.  
   
   
       8 . The method of  claim 1 , wherein the section of metallic tubing comprises a time-temperature-transformation curve where the start of conversion to austentite-ferrite is at least 0.75 seconds after quenching in the low temperature reservoir.  
   
   
       9 . The method of  claim 1 , wherein the heater comprises a flame.  
   
   
       10 . A method for austempering thin walled coiled tubing, comprising: 
 a. extending a section of thin walled metallic tubing having a wall thickness of less than 0.25 inches from a reel mounted coil into a heater as part of a continuous run process;    b. heating the section of metallic tubing to a high temperature in the range of 1300-1600° F. in the heater;    c. moving the section of metallic tubing from the heater to a low temperature reservoir as part of the continuous run process;    d. quenching the section of metallic tubing in the low temperature reservoir to reduce the temperature of the section of metallic tubing to a first low temperature in the range of 500-1000° F. in a time period of less than 3 seconds;    e. allowing the section of metallic tubing to transform to bainite;    f. moving the section of metallic tubing transformed into bainite out of the low temperature reservoir as part of the continuous run process; and    g. cooling the section of metallic tubing to a second low temperature below 100° F.    
   
   
       11 . The method of  claim 10 , further comprising the step of coiling the section of metallic tubing after it reaches the second low temperature.  
   
   
       12 . The method of  claim 10 , wherein the low temperature reservoir used for quenching is a molten salt bath.  
   
   
       13 . The method of  claim 10 , wherein the cooling is accomplished by forced convection.  
   
   
       14 . The method of  claim 10 , wherein the thin walled metallic tubing wall has a thickness of around 0.120 inches.  
   
   
       15 . An austempered thin walled tubing produced by the method of  claim 10 .  
   
   
       16 . A method for austempering and stress relieving a thin walled coiled tubing, comprising: 
 a. extending a section of thin walled metallic tubing having a welded seam and a wall thickness of less than 0.25 inches from a reel mounted coil into a heater as part of a continuous run process;    b. heating the section of metallic tubing to a high temperature in the range of 1300-1600° F. in the heater;    c. moving the section of metallic tubing from the heater to a low temperature reservoir as part of the continuous run process;    d. quenching the section of metallic tubing in a low temperature reservoir to reduce the temperature of the section of metallic tubing to a first low temperature in the range of 500-1000° F. in a time period of less than 3 seconds;    e. allowing the section of metallic tubing to transform to bainite;    f. moving the section of metallic tubing transformed to bainite out of the low temperature reservoir as part of the continuous run process; and    g. cooling the section of metallic tubing to a second low temperature below 100° F.    
   
   
       17 . The method of  claim 15 , wherein the section of metallic tubing comprises a steel alloy with a carbon content greater than or equal to 0.25 and less than or equal to 0.45.  
   
   
       18 . The method of  claim 16 , wherein the section of metallic tubing comprises 4130 alloy steel.  
   
   
       19 . The method of  claim 15 , wherein the low temperature reservoir used for quenching is a molten salt bath.  
   
   
       20 . An austempered thin walled and stress relieved welded tubing produced by the method of  claim 15 .  
   
   
       21 . A thin walled welded tube, comprising: 
 a. an austempered cylindrical body created as part of a continuous run process, the austempered cylindrical body comprising a first seam edge, a second seam edge, and a wall having a thickness of less than 0.25 inches; and    b. a stress relieved welded seam joining the first and second seam edges.    
   
   
       22 . The tubing of  claim 20 , wherein said tubing has a length of at least 200 feet.  
   
   
       23 . The tubing of  claim 21 , wherein said tubing is coiled on a reel.  
   
   
       24 . The tubing of  claim 23 , wherein the tubing comprises a first end region attached to at least one of (i) a motor, (ii) an overshoot jar, (iii) an intensifier, (iv) a landing nipple, (v) a plug catcher, (vi) a casing scraper, (vii) a snake pin, (viii) a downhole tool, or (ix) a valve.  
   
   
       25 . The tubing of  claim 24 , wherein the tubing comprises a second end region opposite the first end region connected to a pump.  
   
   
       26 . An apparatus for austempering thin walled tubing, comprising: 
 a. a heater adapted to accept a section of metallic tubing that has a wall thickness of less than 0.25 inches and heat the section of metallic tubing to a high temperature in the range of 1300-1600° F. in a continuous run process;    b. a low temperature reservoir adapted to accept a moving section of the metallic tubing as part of a continuous run process and to reduce the temperature of the section of metallic tubing to a first low temperature in the range of 500-1000° F. in a time period of less than 3 seconds; and    c. a cooler adapted to cool the section of metallic tubing to a second low temperature below 100° F.    
   
   
       27 . The apparatus of  claim 27 , wherein the heater comprises at least one of (i) an induction heater or (ii) a flame  
   
   
       28 . The apparatus of  claim 28 , wherein the heater is located at least one of (i) proximate the low temperature reservoir or (ii) within the low temperature reservoir.