Method For The Ignition Of In-situ Combustion For The Recovery Of Petroleum

Abstract

A method of initiating in situ combustion in a subterranean hydrocarbon-bearing formation wherein a substance capable of reacting with hydrogen peroxide is introduced into the formation via a well bore and thereafter a mixture of hydrogen peroxide containing from 10 to 20 percent by weight of water is injected to effect an exothermic reaction thereby to increase the temperature of the formation adjacent the well bore to the ignition temperature of the hydrocarbons contained therein and resulting in ignition of those hydrocarbons and the initiation of an in situ combustion.

Description

BACKGROUND OF THE INVENTION

This invention relates generally to a method of igniting and initiating an in situ combustion in a subterranean hydrocarbon-bearing formation.

In modern day production of hydrocarbons from subterranean formations, it is common practice to apply secondary recovery techniques to recover additional quantities of hydrocarbons. One of the more common secondary recovery techniques currently employed is that of in situ combustion. In this method of producing hydrocarbons, in situ combustion is initiated in the hydrocarbon-bearing formation near a well bore penetrating the formation and a combustion front is established. Once the formation has been successfully ignited, a combustion-supporting gas, e.g., an oxygen-containing gas such as compressed air, is injected into the well bore to support and drive the combustion front through the formation, thereby displacing the hydrocarbons in the formation toward a production well from which they are produced.

Successful ignition is generally dependent upon generating a temperature sufficient to support and propagate the combustion front. Among the techniques used for initiating the in situ combustion included in the prior art are various types of ignitors such as downhole heaters, electrical heating devices and combustibles introduced into the well bore. Results from the utilization of many of these techniques have been less than satisfactory, primarily due to the fact that sufficiently high temperatures were not generated to ignite successfully the formation and establish a combustion front.

SUMMARY OF THE INVENTION

The invention herein disclosed provides an improved method of generating sufficiently high temperatures in a well bore adjacent a hydrocarbon-bearing formation to initiate an in situ combustion therein. A high temperature is attained by the reaction of a solution of hydrogen peroxide containing water in amounts of from 10 to 20 percent by weight, which solution is contacted in the well bore with a substance that reacts with the hydrogen peroxide to produce an exothermic reaction. As a result of the high temperature generated thereby within the formation adjacent the well bore, the ignition temperature of the hydrocarbons therein is attained and in situ combustion is initiated.

DESCRIPTION OF THE PREFERRED EMBODIMENT

A broad aspect of the invention comprises introducing into a well bore penetrating a hydrocarbon-bearing formation a substance capable of reacting with hydrogen peroxide whereby the temperature of the formation will be raised at least to the ignition temperature of the hydrocarbons contained therein, and thereafter introducing a solution of hydrogen peroxide and water containing from 10 to 20 percent by weight of water. By the heat set free as a result of the reaction of the hydrogen peroxide with the aforementioned substance, the temperature increases until reaching at least the ignition temperature of the hydrocarbons and oxygen which is formed as a result of the thermal decomposition of hydrogen peroxide burns the ignited hydrocarbons.

The ignition process and the combustion rate are controlled by varying the water content of the hydrogen peroxide. The initiation and the combustion rate are established in a known manner by measuring the pressure and temperature. The ignition process may be halted or the combustion interrupted any time by a sufficient increase of the water content. The preferred water content for ignition is from 10 to 20 weight percent.

The substances capable of reacting with an decomposing the hydrogen peroxide include catalytically active substances and hydrogen peroxide oxidizing or reducing substances. Examples of catalytically active substances are substances with large surfaces, manganese dioxide, ferrous salts, catalases and platinum metals finely divided on an inert supporting material. These substances do not undergo substantial changes in the reaction with hydrogen peroxide or its decomposition process. Examples of hydrogen peroxide oxidizing substances are the permanganates. Examples of hydrogen peroxide reducing substances are hydrazine, hydroxylamine and derivatives thereof. By the reaction of these latter substances with hydrogen peroxide, heat of reaction is set free contributing advantageously to an additional increase of the temperature.

In a preferred embodiment the hydrogen peroxide and the reacting substance are contacted within the formation well bore adjacent the hydrocarbon-bearing formation, for example, by lowering the reacting substance via tubing in the well bore and pumping hydrogen peroxide containing water into the formation through the tubing. If the reacting substance is in solid form, it is first broken into pieces and may be introduced in a perforated container. If the reacting substance is in liquid form, the container is designed as a closed vessel provided with outlet closing means. The container may be lowered either hanging on a rope or by permitting it to fall down. If the substance contains a liquid decomposing agent, it may be provided with a striker by which the closing or bursting disk or the striker itself is crushed causing the decomposing agent to flow out the underground end of the tubing. Prior to pumping the hydrogen peroxide containing water down the tubing, the tubing may be flushed by an agent such as paraffin oil to inhibit the decomposition of the hydrogen peroxide prematurely.

In a particular embodiment of the method of the invention an internal pipe is run through the tubing to the underground of said tubing. The hydrogen peroxide containing water is pumped down either through the annulus or through the internal pipe, while a liquid decomposing agent, e.g., hydrazine, is pumped down through the annulus or through a second tubing. Because of the lesser pipe diameter it is economically justified to treat the internal wall of the internal pipe with decomposition inhibiting substances, e.g., paraffin, polyethylene or bitumen.

By pumping water down the combustion rate may be reduced or the combustion process stopped.

Use is made under particular circumstances which have to be established by pilot tests of the petroliferous layer to serve as the hydrogen peroxide decomposing agent, thereby saving the need for charging the decomposing agent from outside.

The steam developing during the decomposition of the hydrogen peroxide has the advantageous effect of acting as an additional driving agent for the petroleum.

Once the formation has been successfully ignited, a combustion supporting gas, e.g., air, is utilized to drive the combustion front forward toward an adjacent production well from which recovery of hydrocarbons is realized. Alternatively, it may be found advantageous to discontinue injection of the combustion supporting gas and use a water flood to drive the combustion front toward the production well.

Claims

I claim:

1. In the production of hydrocarbons from a hydrocarbon-bearing formation by means of an in situ combustion process, said formation being penetrated by a well bore, the method of initiating in situ combustion comprising the steps of:

a. introducing into said well bore a reducing substance capable of reacting with hydrogen peroxide whereby the temperature of said formation adjacent said well bore will be raised to at least the ignition temperature of said hydrocarbons in said formation by reaction with said hydrogen peroxide,

b. introducing into said well bore a solution of hydrogen peroxide and water whereafter said hydrogen peroxide reacts with said reducing substance to raise the temperature of said formation adjacent said well bore to at least the ignition temperature of said hydrocarbons,

c. thereafter introducing a solution of hydrogen peroxide and water, said hydrogen peroxide thereby being thermally decomposed at said temperature and forming oxygen and effecting in situ combustion of said hydrocarbons adjacent said well bore by reaction with said oxygen.

2. The method of claim 1 wherein said solution of hydrogen peroxide and water contains from 10 to 20 weight percent water.

3. The method of claim 1 wherein said reducing substance capable of reacting with said hydrogen peroxide is hydrazine, hydroxylamine, and derivatives thereof.

4. The method of claim 1 wherein said reducing substance capable of reacting with said hydrogen peroxide is introduced into said well bore via a first tubing means and said solution of hydrogen peroxide and water is introduced via a second tubing means.

5. The method of claim 4 wherein said tubing is coated internally with a decomposition inhibiting substance.

6. The method of claim 5 wherein said decomposition inhibiting substance is paraffin, polyethylene or bitumen.

7. The method of claim 1 wherein said reducing substance is introduced into said well bore via a tubing means and said solution of hydrogen peroxide and water is introduced via the annulus formed between said tubing means and the face of said well bore.

8. The method of claim 7 wherein said tubing is coated internally with a decomposition inhibiting substance.

9. The method of claim 8 wherein said decomposition inhibiting substance is paraffin, polyethylene or bitumen.

10. In the production of hydrocarbons from a hydrocarbon bearing formation by means of an in situ combustion process, said formation being penetrated by a wellbore having a plurality of tubing means therein, thereby forming an annulus between said tubing means and said wellbore, the method of initiating in situ combustion comprising the steps of:

a. introducing into said wellbore a substance capable of reacting with hydrogen peroxide whereby the temperature of said formation adjacent said wellbore will be raised to at least the ignition temperature of said hydrocarbons in said formation by reaction with said hydrogen peroxide;

b. introducing into said wellbore a solution of hydrogen peroxide and water whereafter the said hydrogen peroxide reacts with said substance to raise the temperature of said formation adjacent said wellbore to at least ignition temperature of said hydrocarbons;

c. thereafter introducing a solution of hydrogen peroxide and water, said hydrogen peroxide thereby being thermally decomposed at said temperature and forming oxygen and effecting in situ combustion of said hydrocarbons adjacent said wellbore by reaction with said oxygen.

11. The method of claim 10 wherein said substance capable of reacting with hydrogen peroxide is introduced via one of said tubing means and thereafter said solution of hydrogen peroxide and water is introduced via another of said tubing means.

12. The method of claim 11 wherein said tubing is coated internally with a decomposition inhibiting substance.

13. The method of claim 12 wherein said decomposition inhibiting substance is paraffin, polyethylene or bitumen.

14. The method of claim 10 wherein said substance capable of reacting with hydrogen peroxide is introduced by one of said tubing means and said solution of hydrogen peroxide and water is introduced into said annulus defined between said tubing means and said wellbore.

15. The method of claim 10 wherein said solution of hydrogen peroxide and water contains from 10 to 20 weight percent of water.

16. The method of claim 10 wherein said substance capable of reacting with said hydrogen peroxide is an oxidizing substance.

17. The method of claim 16 wherein said oxidizing substance is a permanganate.

18. The method of claim 10 wherein said substance capable of reacting with said hydrogen peroxide is a reducing substance.

19. The method of claim 18 wherein said reducing substance is hydrazine, hydroxylamine and derivatives thereof.

20. The method of claim 10 wherein said substance capable of reacting with hydrogen peroxide is a component of said hydrocarbons contained in said hydrocarbon-bearing formation.

21. The method of claim 10 wherein said substance capable of reacting with said hydrogen peroxide is a catalytically active substance.

22. The method of claim 10 wherein said catalytically active substance are substances with large surfaces, manganese dioxide, ferrous salts, catalases and platinum metals, finely divided of an inert supporting material.