Process for downhole heating

Abstract

Neutral electrolytes, relatively neutral electrolytes, metal oxides, metal hydroxides and/or organic exothermic hydration chemicals may be hydrated with water at a controlled location in a subterranean formation to generate sufficient exothermic heat to at least soften and possibly melt and flow bitumen at or near the location. This controlled and localized heating would be useful in drilling through relatively thick bitumen or “tar” beds. In one non-limiting embodiment the exothermic hydration reaction does not generate appreciable amounts of gas. Alternatively, the exothermic reaction may be used to liberate hydrocarbons from gas hydrates in an embodiment where the evolution of gas is acceptable.

1 . A method for providing localized heating in a subterranean formation comprising: 
 placing at a location in the subterranean formation in any order: 
 an exothermic hydration chemical, and  
 an effective amount of water in contact with the exothermic hydration chemical to cause an exothermic reaction; and  
   heating the location.    
   
   
       2 . The method of  claim 1  where bitumen is present at the location, the exothermic reaction does not generate an appreciable amount of gas, and the heating is sufficient to at least soften the bitumen.  
   
   
       3 . The method of  claim 2  where the exothermic hydration chemical is selected from the group consisting of a relatively neutral electrolyte, a metal oxide, a metal hydroxide, and an organic compound, all capable of exothermic reaction without generating an appreciable amount of gas.  
   
   
       4 . The method of  claim 3  where the exothermic hydration chemical is selected from the group consisting of aluminum chloride, NaOH, KOH, halogen salts, sulfate salts, calcium oxide, barium oxide, and mixtures thereof.  
   
   
       5 . The method of  claim 1  where the exothermic hydration chemical is encapsulated in a material selected from the group consisting of wax, polymer wax, solid fatty acids, polymers, or is absorbed onto or bound to a substrate material where the material melts or disintegrates at the location.  
   
   
       6 . The method of  claim 1  where the exothermic hydration chemical has a heat of hydration of at least 40 kJ/mol.  
   
   
       7 . The method of  claim 1  where gas hydrates are present at the location, the exothermic reaction may generate an appreciable amount of gas, and the heating is sufficient to release at least a portion of hydrocarbons bound in the hydrates.  
   
   
       8 . The method of  claim 1  where the exothermic reaction chemical is placed at the location in a delivery medium selected from the group consisting of alcohols, glycols, heat transfer fluids, organic oils, and mixtures thereof.  
   
   
       9 . A method for providing localized heating in a subterranean formation comprising: 
 placing at a location in the subterranean formation where bitumen is present in any order: 
 an exothermic hydration chemical selected from the group consisting of a relatively neutral electrolyte, a metal oxide, a metal hydroxide, and an organic compound, and  
 an effective amount of water in contact with the exothermic hydration chemical to cause an exothermic reaction without generating an appreciable amount of gas; and  
   heating the location sufficiently to at least soften the bitumen.    
   
   
       10 . The method of  claim 9  where the exothermic hydration chemical is selected from the group consisting of aluminum chloride, NaOH, KOH, halogen salts, sulfate salts, calcium oxide, barium oxide, and mixtures thereof.  
   
   
       11 . The method of  claim 9  where the exothermic hydration chemical is encapsulated in a material selected from the group consisting of wax, polymer wax, solid fatty acids, polymers, or is absorbed onto or bound to a substrate material, where the material melts or disintegrates at the location.  
   
   
       12 . The method of  claim 9  where the exothermic hydration chemical has a heat of hydration of at least 40 kJ/mol.  
   
   
       13 . The method of  claim 9  where the exothermic reaction chemical is placed at the location in a delivery medium selected from the group consisting of alcohols, glycols, heat transfer fluids, organic oils, and mixtures thereof.  
   
   
       14 . A method for providing localized heating in a subterranean formation comprising: 
 placing at a location in the subterranean formation in any order: 
 an exothermic hydration chemical selected from the group consisting of a relatively neutral electrolyte, a metal oxide, a metal hydroxide, and an organic compound, where the exothermic hydration chemical has a heat of hydration of at least 40 kJ/mol, and  
 an effective amount of water in contact with the exothermic hydration chemical to cause an exothermic reaction without generating an appreciable amount of gas; and  
   heating the location.    
   
   
       15 . The method of  claim 14  where bitumen is present at the location and the heating is sufficient to at least soften the bitumen.  
   
   
       16 . The method of  claim 14  where the exothermic hydration chemical is selected from the group consisting of aluminum chloride, NaOH, KOH, halogen salts, sulfate salts, calcium oxide, barium oxide, and mixtures thereof.  
   
   
       17 . The method of  claim 14  where the exothermic hydration chemical is encapsulated in a material selected from the group consisting of wax, polymer wax, solid fatty acids, polymers, or is absorbed onto or bound to a substrate material, where the material melts or disintegrates at the location.  
   
   
       18 . A method for providing localized heating in a subterranean formation comprising: 
 placing at a location in the subterranean formation containing gas hydrates an exothermic hydration chemical, and    reacting at least a portion of the water in the gas hydrates with the exothermic hydration chemical to cause an exothermic reaction to release at least a portion of hydrocarbons bound in the hydrates.    
   
   
       19 . The method of  claim 18  where the exothermic hydration chemical is selected from the group consisting of a relatively neutral electrolyte, a metal oxide, a metal hydroxide, an organic compound, a hydrogen halide and perchloric acid.  
   
   
       20 . The method of  claim 19  where the exothermic hydration chemical is selected from the group consisting of aluminum chloride, NaOH, KOH, halogen salts, sulfate salts, calcium oxide, barium oxide, hydrogen halides, perchloric acid, and mixtures thereof.  
   
   
       21 . The method of  claim 18  where the exothermic hydration chemical is encapsulated in a material selected from the group consisting of wax, polymer wax, solid fatty acids, polymers, or is absorbed onto or bound to a substrate material where the material melts or disintegrates at the location.  
   
   
       22 . The method of  claim 18  where the exothermic hydration chemical has a heat of hydration of at least 40 kJ/mol.  
   
   
       23 . The method of  claim 18  where the exothermic reaction chemical is placed at the location in a delivery medium selected from the group consisting of alcohols, glycols, heat transfer fluids, organic oils, and mixtures thereof.