Production of hydrocarbons from underground formations

Abstract

A method for recovering hydrocarbons by injecting a mixture of oxidizing gas and steam into a lateral conduit in a hydrocarbon-containing formation to produce a product gas and, based on values contained in such gas, controlling the reactions between mixtures of oxidizing gas and steam and hydrocarbons in the formation to optimize the Btu value of the product gas.

What is claimed is: 
     
       1. A method for converting petroleum within an underground formation into combustible product gas and bringing the so-formed product gas to the Earth's surface for subsequent distribution comprising connecting at least one input well with at least one producing well by a lateral connecting hole which at least in part penetrates an underground formation containing petroleum; packing said connecting hole with a permeable material so that said connecting hole has a permeability in excess of the permeability of said underground formation; injecting oxidizing gas and steam down said input well into said lateral connecting hole to react with petroleum in said formation by partial oxidation and by thermal cracking to form a product gas containing sufficient fractions of at least one of the components carbon monoxide, hydrogen and methane to be combustible, producing said product gas from said formation through said producing well; analyzing said product gas for values of C 1  and C 2  hydrocarbons, carbon monoxide and carbon dioxide; and controlling the reactions within said connecting hole based on said values to optimize the Btu value of said product gas. 
     
     
       2. The method of claim 1 further characterized by controlling said reactions to provide a carbon monoxide-to-carbon dioxide ratio of from 1 to 2 and a C 1  plus C 2  hydrocarbon volume percentage of 10 percent to 30 percent of the total product gas. 
     
     
       3. The method of claim 2 further characterized in that the permeability of said connecting hole is at least ten times the permeability of said formation. 
     
     
       4. The method of claim 3 further characterized by adding a catalyst to the lateral connecting hole to assist in controlling the reactions. 
     
     
       5. The method of claim 3 further characterized in that a slotted tube is inserted into said lateral connecting hole. 
     
     
       6. A method of converting petroleum within an underground formation into combustible product gas and bringing the so-formed product gas to the earth's surface for subsequent distribution comprising connecting at least one input well with at least one producing well by a lateral connecting hole which at least in part penetrates an underground formation containing petroleum; inserting a slotted tube into said lateral connecting hole; packing said tube with a permeable material so that said tube has a permeability at least 10 times the permeability of said underground formation; injecting oxidizing gas and steam down said input well into said tube to react with petroleum in said formation by partial oxidation and by thermal cracking to form a product gas containing sufficient fractions of at least one of the components carbon monoxide, hydrogen and methane to be combustible; producing said product gas from said formation through said producing well; analyzing said product gas for values of C 1  and C 2  hydrocarbons, carbon monoxide and carbon dioxide; and controlling the reactions within said tube to maintain a carbon monoxide-to-carbon dioxide ratio in the range from 1 to 2 and a C 1  plus C 2  hydrocarbon volume percentage in the range from 10 percent to 30 percent of the total product gas. 
     
     
       7. The method of claim 6 further characterized in that the initial injection mixture of oxidizing gas and steam is maintained at between 1 to 3 parts oxygen and 1 to 9 parts steam and the pressure of oxidizing gas and steam injected into said tube is between 1.1 to 2 times the pressure in said formation and that back pressure between 0.5 to 0.9 times the formation pressure is held on said producing well. 
     
     
       8. The method of claim 7 further characterized in that the initial injection rate of said oxidizing gas and steam is maintained at a value between 8 to 9 void volumes per minute. .Iadd. 9. A method for converting hydrocarbons within an underground formation into combustible product gas and bringing the so-formed product gas to the earth's surface for subsequent distribution comprising connecting at least one input well with at least one producing well by a lateral connecting hole which at least in part penetrates an underground formation containing hydrocarbons, packing said connecting hole with a permeable material so that said connecting hole has a permeability in excess of the permeability of said underground formation; injecting oxidizing gas and steam down said input well into said lateral connecting hole to react with hydrocarbons in said formation by partial oxidation and by thermal cracking to form a product gas containing sufficient fractions of at least one of the components carbon monoxide, hydrogen and methane to be combustible, producing said product gas from said formation through said producing well; analyzing said product gas for values of C 1  and C 2  hydrocarbons, carbon monoxide and carbon dioxide; and controlling the reactions within said connecting hole based on said values to optimize the Btu value of said product gas. .Iaddend..Iadd. 10. The method of claim 9 further characterized by controlling said reactions to provide a carbon monoxide-to-carbon dioxide ratio of from 1 to 2 and a C 1  plus C 2  hydrocarbon volume percentage of 10 percent to 30 percent of the total product gas. .Iaddend..Iadd. 11. The method of claim 10 further characterized in that the permeability of said connecting hole is at least ten times the permeability of said formation. .Iaddend. .Iadd. 12. The method of claim 11 further characterized by adding a catalyst to the lateral connecting hole to assist in controlling the reactions. .Iaddend..Iadd. 13. The method of claim 11 further characterized in that a slotted tube is inserted into said lateral connecting hole. .Iaddend..Iadd. 14. A method of converting hydrocarbons within an underground formation into combustible product gas and bringing the so-formed product gas to the earth's surface for subsequent distribution comprising connecting at least one input well with at least one producing well by a lateral connecting hole which at least in part penetrates an underground formation containing hydrocarbons; inserting a slotted tube into said lateral connecting hole; packing said tube with a permeable material so that said tube has a permeability at least 10 times the permeability of said underground formation; injecting oxidizing gas and steam down said input well into said tube to react with hydrocarbons in said formation by partial oxidation and by thermal cracking to form a product gas containing sufficient fractions of at least one of the components carbon monoxide, hydrogen and methane to be combustible; producing said product gas from said formation through said producing well; analyzing said product gas for values of C 1  and C 2  hydrocarbons, carbon monoxide and carbon dioxide; and controlling the reactions within said tube to maintain a carbon monoxide-to-carbon dioxide ratio in the range from 1 to 2 and a C 1  plus C.sub. 2 hydrocarbon volume percentage in the range from 10 percent to 30 percent of the total product gas. .Iaddend. .Iadd. 15. The method of claim 14 further characterized in that the initial injection mixture of oxidizing gas and steam is maintained at between 1 to 3 parts oxygen and 1 to 9 parts steam and the pressure of oxidizing gas and steam injected into said tube is between 1.1 to 2 times the pressure in said formation and that back pressure between 0.5 to 0.9 times the formation pressure is held on said producing well. .Iaddend..Iadd. 16. The method of claim 15 further characterized in that the initial injection rate of said oxidizing gas and steam is maintained at a value between 8 to 9 void volumes per minute. .Iaddend.