Toe casing

Abstract

A toe casing is made of a material different from conventional casing, and may be deployed in an open-hole section of a well that is not economically accessible by conventional casing. The toe casing may be made of a material that more easily conforms to the well bore, such as aluminum alloy, titanium alloy, or a composite material. The toe casing may be secured to and deployed at the end of a conventional casing string for the purpose of assisting the casing in reaching a desired depth, allowing for improved hydrocarbon production.

1 . A system comprising:
 a tubular casing section comprising a first material and extending through a first section of a subterranean well; and   a toe casing section coupled to a lower end of the tubular casing section and extending into an open-hole section of the subterranean well, the toe casing section comprising a second material different from the first material.   
     
     
         2 . The system of  claim 1 , wherein the first material comprises steel, and the second material comprises an aluminum alloy. 
     
     
         3 . The system of  claim 1 , wherein the toe casing section has a nominal length of 20 feet. 
     
     
         4 . The system of  claim 2 , wherein the toe casing section has a length sufficient to assist the whole casing string to reach desired depth. 
     
     
         5 . The system of  claim 1 , wherein the toe casing section comprises a plurality of modular sections having a nominal length of 10 to 45 feet. 
     
     
         6 . The system of  claim 1 , wherein the toe casing section has an outer diameter of at least about 3 inches to 36 inches. 
     
     
         7 . The system of  claim 5 , wherein the toe casing section has a wall thickness of between about 0.25 inches to 1.5 inches. 
     
     
         8 . The system of  claim 1 , wherein the toe casing section comprises a shoe track. 
     
     
         9 . The system of  claim 1 , wherein the open-hole section is off-vertical and the toe casing section extends at least 5,000 to 20,000 feet into the off-vertical open-hole section. 
     
     
         10 . A system comprising:
 a tubular casing section comprising a first material and extending through a generally vertical section of a subterranean well and into a portion of an off-vertical section of the subterranean well continuous with the vertical section; and   a toe casing section coupled to a distal end of the tubular casing section and extending into an open-hole section of the off-vertical section beyond a limit of the casing section, the toe casing section comprising a second material different from the first material.   
     
     
         11 . The system of  claim 10 , wherein the first material comprises steel, and the second material comprises an aluminum alloy. 
     
     
         12 . The system of  claim 10 , wherein the toe casing section has a nominal length of 20 feet. 
     
     
         13 . The system of  claim 10 , wherein the toe casing section has an outer diameter of at least about 3 inches to 36 inches. 
     
     
         14 . The system of  claim 13 , wherein the toe casing section has a wall thickness of between about 0.25 inches to 1.5 inches. 
     
     
         15 . The system of  claim 10 , wherein the toe casing section comprises at least one shoe track. 
     
     
         16 . The system of  claim 10 , wherein the toe casing section extends at least 5,000 to 20,000 feet into the off-vertical open-hole section. 
     
     
         17 . A method comprising:
 assembling a toe casing section comprising a toe casing material;   deploying the toe casing section into a well;   assembling a casing section comprising a casing material different from the toe casing material, a lower end of the casing section being secured to an upper end of the toe casing section;   deploying the casing section into the well to set the toe casing section into an open-hole section of the well.   
     
     
         18 . The method of  claim 17 , wherein the open-hole section is generally off-vertical. 
     
     
         19 . The method of  claim 17 , wherein the toe casing section comprises at least one shoe track. 
     
     
         20 . The method of  claim 17 , wherein the toe casing material comprises an aluminum alloy and the casing material comprises steel.