Oilfield Enhanced in Situ Combustion Process

Abstract

A method for recovery of oil in toe-to-heal in-situ combustion processes from underground petroleum formations, having at least one injection well for injecting oxidizing gas into the underground formation and one production well having a substantially horizontal leg and a substantially vertical production well connected thereto wherein the substantially horizontal leg extends towed the injection well, the horizontal leg having a heel portion in the vicinity of its connection to the vertical production well and a toe portion at the opposite end of the horizontal leg proximate the injection well. The improvement comprises either i) providing tubing inside the production well and injecting steam or water into the horizontal leg portion via the tubing so that steam/water is conveyed to the toe portion, ii) injecting steam/water into the injection well in additional to oxidizing gas, or iii) providing and carrying out both of steps i) and ii).

1 . A process for extracting liquid hydrocarbons from an underground reservoir comprising the steps of:
 (a) providing at least one injection well for injecting an oxidizing gas into the underground reservoir;   (b) providing at least one production well having a substantially horizontal leg and a substantially vertical production well connected thereto, wherein the substantially horizontal leg extends toward the injection well, the horizontal leg having a heel portion in the vicinity of its connection to the vertical production well and a toe portion at the opposite end of the horizontal leg, wherein the toe portion is closer to the injection well than the heel portion;   (c) injecting an oxidizing gas through the injection well to conduct in situ combustion, so that combustion gases are produced so as to cause the combustion gases to progressively advance as a front, substantially perpendicular to the horizontal leg, in the direction from the toe portion to the heel portion of the horizontal leg, and fluids drain into the horizontal leg;   (d) providing a tubing inside the production well within said vertical leg and at least a portion of said horizontal leg for the purpose of injecting steam, water or non-oxidizing gas into said horizontal leg portion of said production well proximate a combustion front formed at a horizontal distance along said horizontal leg of said production well;   (e) injecting a medium selected from the group of mediums comprising steam, water, or non-oxidizing gas, into said tubing so that said medium is conveyed proximate said toe portion of said horizontal leg portion via said tubing; and   (f) recovering hydrocarbons in the horizontal leg of the production well from said production well.   
   
   
       2 . The process of  claim 1  wherein said medium is water, and said water is heated at the time of supply to the reservoir to become steam. 
   
   
       3 . The process of  claim 1  wherein the injection well is a vertical, slant or horizontal well. 
   
   
       4 . The process of  claim 1 , said step of injecting said medium further serving to pressurize said horizontal well to a pressure to permit injection of said medium into the underground reservoir. 
   
   
       5 . The process of  claim 1  wherein a non-oxidizing gas is injected into said tubing alone or in combination with steam or water. 
   
   
       6 . The process of  claim 1  wherein an open end of the tubing is in the vicinity of the toe of the horizontal section so as to permit delivery of steam or heated non-oxidizing gas to said toe. 
   
   
       7 . The process of  claim 1  or  6  wherein the tubing is partially pulled back or otherwise repositioned for the purpose of altering a point of injection of the steam, water or non-oxidizing gas along the horizontal leg. 
   
   
       8 . The process of  claim 1  wherein the steam, water or non-oxidizing gas or gases are injected continuously or periodically. 
   
   
       9 . A process for extracting liquid hydrocarbons from an underground reservoir, comprising the steps of:
 (a) providing at least one injection well for injecting an oxidizing gas into an upper part of an underground reservoir;   (b) said at least one injection well further adapted for injecting steam, a non-oxidizing gas, or water which is subsequently heated to steam, into a lower part of an underground reservoir;   (c) providing at least one production well having a substantially horizontal leg and a substantially vertical production well connected thereto, wherein the substantially horizontal leg extends toward the injection well, the horizontal leg having a heel portion in the vicinity of its connection to the vertical production well and a toe portion at the opposite end of the horizontal leg, wherein the toe portion is closer to the injection well than the heel portion;   (d) injecting an oxidizing gas through the injection well for in situ combustion, so that combustion gases are produced, wherein the combustion gases progressively advance as a front, substantially perpendicular to the horizontal leg, in the direction from the toe portion to the heel portion of the horizontal leg, and fluids drain into the horizontal leg;   (e) injecting a medium, wherein said medium is selected from the group of mediums comprising steam, water or a non-oxidizing gas, into said injection well ; and   (f) recovering hydrocarbons in the horizontal leg of the production well from said production well.   
   
   
       10 . A process for extracting liquid hydrocarbons from an underground reservoir, comprising the steps of:
 (a) providing at least one oxidizing gas injection well for injecting an oxidizing gas into an upper part of an underground reservoir;   (b) providing at least one other injection well for injecting steam, a non-oxidizing gas, or water which is subsequently heated to steam, into a lower part of an underground reservoir;   (c) providing at least one production well having a substantially horizontal leg and a substantially vertical production well connected thereto, wherein the substantially horizontal leg extends toward the injection well, the horizontal leg having a heel portion in the vicinity of its connection to the vertical production well and a toe portion at the opposite end of the horizontal leg, wherein the toe portion is closer to the oxidizing gas injection well than the heel portion;   (d) injecting an oxidizing gas through the oxidizing injection well for in situ combustion, so that combustion gases are produced, wherein the combustion gases progressively advance as a front, substantially perpendicular to the horizontal leg, in the direction from the toe portion to the heel portion of the horizontal leg, and fluids drain into the horizontal leg;   (e) injecting a medium, wherein said medium is selected from the group of mediums comprising steam, water or a non-oxidizing gas, into said other injection well; and   (f) recovering hydrocarbons in the horizontal leg of the production well from said production well.   
   
   
       11 . The process of  claim 9  or  10  wherein said medium is water, and said water is subsequently heated to become steam and said steam is provided to said lower part of the formation via a distal end of said injection well. 
   
   
       12 . A method for extracting liquid hydrocarbons from an underground reservoir, comprising the steps of:
 (a) providing at least one injection well for injecting an oxidizing gas into an upper part of an underground reservoir;   (b) said at least one injection well further adapted for injecting steam, a non-oxidizing gas, or water which is subsequently heated to steam, into a lower part of an underground reservoir;   (c) providing at least one production well having a substantially horizontal leg and a substantially vertical production well connected thereto, wherein the substantially horizontal leg extends toward the injection well, the horizontal leg having a heel portion in the vicinity of its connection to the vertical production well and a toe portion at the opposite end of the horizontal leg, wherein the toe portion is closer to the injection well than the heel portion;   (d) providing a tubing inside the production well within said vertical leg and at least a portion of said horizontal leg for the purpose of injecting steam, water or non-oxidizing gas into said horizontal leg portion of said production well;   (e) injecting an oxidizing gas through the injection well for in situ combustion, so that combustion gases are produced, wherein the combustion gases progressively advance as a front, substantially perpendicular to the horizontal leg, in the direction from the toe portion to the heel portion of the horizontal leg, and fluids drain into the horizontal leg;   (f) injecting a medium, wherein said medium is selected from the group of mediums comprising steam, water or a non-oxidizing gas, into said injection well and into said tubing; and   (g) recovering hydrocarbons in the horizontal leg of the production well from said production well.   
   
   
       13 . The method of  claim 12  wherein said medium is water, and said water is heated at the time of supply to the reservoir to become steam. 
   
   
       14 . The method of  claim 12  wherein the injection well is a vertical, slant or horizontal well. 
   
   
       15 . A method for extracting liquid hydrocarbons from an underground reservoir, comprising the steps of:
 (a) providing at least one injection well for injecting an oxidizing gas into an upper part of an underground reservoir;   (b) providing at least one other injection well for injecting steam, a non-oxidizing gas, or water which is subsequently heated to steam, into a lower part of an underground reservoir;   (c) providing at least one production well having a substantially horizontal leg and a substantially vertical production well connected thereto, wherein the substantially horizontal leg extends toward the injection well, the horizontal leg having a heel portion in the vicinity of its connection to the vertical production well and a toe portion at the opposite end of the horizontal leg, wherein the toe portion is closer to the injection well than the heel portion;   (d) providing a tubing inside the production well within said vertical leg and at least a portion of said horizontal leg for the purpose of injecting steam, water or non-oxidizing gas into said horizontal leg portion of said production well;   (e) injecting an oxidizing gas through the injection well for in situ combustion, so that combustion gases are produced, wherein the combustion gases progressively advance as a front, substantially perpendicular to the horizontal leg, in the direction from the toe portion to the heel portion of the horizontal leg, and fluids drain into the horizontal leg;   (f) injecting a medium, wherein said medium is selected from the group of mediums comprising steam, water or a non-oxidizing gas, into said other injection well and into said tubing; and   (g) recovering hydrocarbons in the horizontal leg of the production well from said production well.   
   
   
       16 . The method of  claim 15  wherein said medium is water, and said water is heated at the time of supply to the reservoir to become steam. 
   
   
       17 . The method of  claim 15  wherein the injection well is a vertical, slant or horizontal well.