RADIO-FREQUENCY ENHANCEMENT AND FACILITATION OF IN-SITU COMBUSTION

Abstract

Radio frequency radiation is introduced downhole to heat one or more components of an in-situ hydrocarbon mixture. The mixture is heated to a temperature conducive to auto-ignition. Upon heating, an oxidant is introduced at conditions supportive of auto-ignition. The combined oxidant/hydrocarbon mixture is then allowed to auto-ignite and combust to form a partially upgraded mixture. Certain embodiments include introducing an ignition agent to facilitate auto-ignition. The radio frequency radiation may be supplemented, continued, or varied as desired to maintain, facilitate, or manage the resulting combustion process. In some cases, an activator is introduced to the formation to interact with the generated radio frequency radiation to enhance hydrocarbon heating. Advantages of certain embodiments include lower cost, reduced heating/ignition equipment, higher efficiencies, increased hydrocarbon recovery, and fewer auto-ignition failures.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a non-provisional application which claims benefit under 35 USC §119(e) to U.S. Provisional Application Ser. No. 61/774,745 filed Mar. 8, 2013, entitled “RADIO-FREQUENCY ENHANCEMENT AND FACILITATION OF IN-SITU COMBUSTION,” which is incorporated herein in its entirety.

FIELD OF THE INVENTION

The present invention relates generally to methods and systems for facilitating in-situ combustion of hydrocarbons using generated radio frequency radiation.

BACKGROUND

In the recovery of hydrocarbons from subterranean reservoirs, it usually is possible to recover only a minor portion of the oil originally in place in a reservoir by primary recovery methods, that is, those methods which use only the natural forces present in the reservoir. A variety of supplemental recovery techniques are employed to increase the recovery of oil from subterranean reservoirs. These supplemental techniques, which are commonly referred to as secondary recovery operations, typically involve enhancing recovery of the hydrocarbons in place with a secondary fluid such as water or steam to “sweep” the hydrocarbons towards suitable production wells.

Another secondary recovery process involves an in situ combustion technique. In this procedure, a portion of the reservoir oil is burned or oxidized in situ to create a combustion front. This combustion front is typically advanced through the reservoir in the direction of one or more production wells by the injection of a combustion supporting gas through one or more injection wells. Some of the benefits of in situ combustion can include one or more of the following benefits: reservoir pressurization, mobilization of combustion hydrocarbons, partial upgrading of the reservoir hydrocarbons, flue gas stripping of the reservoir hydrocarbons, oil swelling, improvement in the density and viscosity characteristics of the reservoir hydrocarbons, increased mobility of the reservoir hydrocarbons, injected gas substitution (e.g. air instead of methane), supercritical steam effects, miscibility effects, increased hydrocarbon reactivity, significantly lower greenhouse gas emissions, and lower production and capital costs than competing technologies.

In situ combustion processes are notoriously difficult to predict and control. They are often regarded as a high-risk process by many, primarily because of repeated failures of early field tests. One of the difficulties of situ combustion processes is the complexity of initiating ignition and managing the subsequent developing combustion front. Often, ignition of the reservoir crude requires heating. This heating is sometimes started by lowering a heater or igniter into an injection well. In some cases, the injected air is heated to provide some or all of the heat required to initiate ignition.

Unfortunately, the conventional methods for initiating and managing in situ combustion suffer from a variety of disadvantages. For one, the heaters and furnaces used to supply the heat needed to initiate and manage the combustion processes are costly and require undesirable equipment footprints at the surface. Another disadvantage is the time required to run such heaters and/or igniters downhole.

Accordingly, enhanced methods for igniting and managing in situ combustion processes are needed that address one or more disadvantages of the prior art.

SUMMARY

The present invention relates generally to methods and systems for facilitating in-situ combustion of hydrocarbons using generated radio frequency radiation.

One example of a method for facilitating in-situ combustion of an in-situ hydrocarbon mixture using a generated radio frequency radiation comprises the steps of: introducing one or more activators into a subterranean formation; introducing the generated radio frequency radiation into the subterranean formation, wherein the generated radio frequency radiation is from about 0.1 MHz to about 1 GHz; introducing an ignition agent into the subterranean formation; allowing the generated radio frequency radiation to heat the one or more activators; allowing the activators to heat the in-situ hydrocarbons by conductive heating to a first temperature that is supportive of auto-ignition of the in-situ hydrocarbon mixture, wherein the generated radio frequency radiation is from about 0.1 MHz to about 1 GHz; introducing an oxidant into the subterranean formation to form a combined mixture of oxidant and in-situ hydrocarbon mixture; allowing the combined mixture of the oxidant and the in-situ hydrocarbon mixture to auto-ignite; and allowing the combined mixture to combust through a combustion process to form a second in-situ hydrocarbon mixture.

One example of a method for facilitating in-situ combustion of an in-situ hydrocarbon mixture using a generated radio frequency radiation comprises the steps of: introducing the generated radio frequency radiation into a subterranean formation; allowing the generated radio frequency radiation to heat one or more components of the in-situ hydrocarbon mixture to a first temperature that is supportive of auto-ignition of the in-situ hydrocarbon mixture, wherein the generated radio frequency radiation is from about 0.1 MHz to about 1 GHz; introducing an ignition agent into the subterranean formation; introducing an oxidant into the subterranean formation to form a combined mixture of oxidant and in-situ hydrocarbon mixture; allowing the combined mixture of the oxidant and the in-situ hydrocarbon mixture to auto-ignite; and allowing the combined mixture to combust through a combustion process to form a second in-situ hydrocarbon mixture.

The features and advantages of the present invention will be apparent to those skilled in the art. While numerous changes may be made by those skilled in the art, such changes are within the spirit of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the present disclosure and advantages thereof may be acquired by referring to the following description taken in conjunction with the accompanying figures, wherein:

FIG. 1 illustrates an example of a system using a generated radio frequency radiation for facilitating in situ combustion of a hydrocarbon mixture in accordance with one embodiment of the present invention.

FIG. 2 illustrates an example of a combustion front developed in a hydrocarbon reservoir by use of generated radio frequency radiation in accordance with one embodiment of the present invention.

FIG. 3 illustrates an example of a system using a generated radio frequency radiation in combination with a plurality of activators for facilitating in situ combustion of a hydrocarbon mixture in accordance with one embodiment of the present invention.

While the present invention is susceptible to various modifications and alternative forms, specific exemplary embodiments thereof have been shown by way of example in the drawings and are herein described in detail. It should be understood, however, that the description herein of specific embodiments is not intended to limit the invention to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.

DETAILED DESCRIPTION

The present invention relates generally to methods and systems for facilitating in-situ combustion of hydrocarbons using generated radio frequency radiation.

In certain embodiments, methods and systems are provided for facilitating in-situ combustion of an in-situ hydrocarbon mixture using generated radio frequency radiation. In one embodiment, generated radio frequency radiation is introduced downhole to heat one or more components of an in-situ hydrocarbon mixture. The mixture is then heated to a temperature conducive to auto-ignition. Upon heating the hydrocarbon mixture, an oxidant may be introduced into the subterranean formation at conditions supportive of auto-ignition. The combined oxidant/hydrocarbon mixture is then allowed to auto-ignite and combust to form a partially upgraded mixture. In some embodiments, an ignition agent is introduced to facilitate auto-ignition of the hydrocarbon mixture. In certain embodiments, the generated radio frequency radiation may be supplemented, continued, or varied as desired to maintain, facilitate, or manage the resulting combustion process. In some cases, one or more activators may be introduced into the subterranean formation to interact with the generated radio frequency radiation and enhance heating of the hydrocarbons therein.

Advantages of the enhanced methods and systems described herein include one or more of the following advantages: lower cost, higher efficiencies, higher recovery of reservoir hydrocarbons, and fewer auto-ignition failures. Additionally, the methods herein eliminate or at least reduce the heating and/or ignition equipment that would otherwise be required without the radio frequency radiation heating described herein. Other features, embodiments, and advantages will be apparent from the disclosure herein.

Reference will now be made in detail to embodiments of the invention, one or more examples of which are illustrated in the accompanying drawings. Each example is provided by way of explanation of the invention, not as a limitation of the invention. It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For instance, features illustrated or described as part of one embodiment can be used on another embodiment to yield a still further embodiment. Thus, it is intended that the present invention cover such modifications and variations that come within the scope of the invention.

FIG. 1 illustrates an example of a system using a generated radio frequency radiation to facilitate in situ combustion in accordance with one embodiment of the present invention. In this example, injection well 120 and producing well 160 both intersect subterranean formation 105. Hydrocarbon reservoir 107, situated in subterranean formation 105, contains hydrocarbons, namely in situ hydrocarbon mixture 51. It is desired to produce some of all of the hydrocarbons in hydrocarbon reservoir 107.

Under certain conditions, one way to enhance recovery of hydrocarbons in place is to conduct an in situ combustion process. In situ combustion aids in the recovery of hydrocarbons in place by, in part, upgrading the hydrocarbons and increasing their mobility, among other mechanisms. In situ hydrocarbon mixture 51 is typically not at sufficiently high temperatures to support ignition and the subsequent desired combustion development. Accordingly, heat must be applied to support the desired in situ combustion process. To accomplish this heat introduction, generated radio frequency radiation may be introduced into subterranean formation 105 by way of energy generator 122 and antenna 124.

Antenna 124 may comprise any antenna known in the art suitable for introducing electromagnetic radiation into subterranean formation 105. In certain embodiments, the frequency of the generated radio frequency radiation is from about 0.1 MHz to about 1 GHz. In some embodiments, the frequency of the generated radio frequency radiation is from about 300 MHz to about 1 GHz.

Accordingly, the generated radio frequency radiation heats one or more components of the in-situ hydrocarbon mixture to a temperature supportive of auto-ignition of the in-situ hydrocarbon mixture (i.e. with or without later introduced oxidant). Upon heating the in-situ hydrocarbon mixture to a desired temperature supportive of auto-ignition, an oxidant may be introduced into the subterranean formation to form a combined mixture of the oxidant and the in-situ hydrocarbon mixture. The oxidant may be introduced by air compressor 140 by way of injection well 120. The oxidant may be air, an oxygen-enriched mixture, a gas mixture comprising oxygen, or any combination thereof.

Upon reaching sufficient auto-ignition conditions, the combined mixture of oxidant and in-situ hydrocarbon mixture 51 may then auto-ignite. Turning to FIG. 2 (where like reference numerals refer to like elements corresponding to FIG. 1), the combined mixture then combusts to form combustion front 50. In this way, the in-situ combustion process converts in situ hydrocarbon mixture 51 into second in-situ hydrocarbon mixture 52.

In some embodiments, an ignition agent may be introduced into subterranean formation 105 to facilitate ignition of the in-situ hydrocarbon mixture, particularly where autoignition is known to be problematic. While it may be preferred to introduce the autoignition agent before injecting the oxidant, it is recognized that the autoignition agent may be introduced at any time before, during, or after radiofrequency heating. The ignition agent may comprise any compound that facilitates autoignition of the in-situ hydrocarbon mixture.

Suitable examples of autoignition agents include, but are not limited to, tung oil, linseed oil, red oil, castor oil, turpentine, tall oil, a fatty acid of tall oil, oleic acid, a fatty acid of linseed oil, diesel oil, magnesium powder, light naptha, any combination thereof. The ignition agent may include a combustion catalyst such as cobalt naphthenate, cobalt tallate, cobalt octoate, or any combination thereof. In certain embodiments, the ignition agent is an aliphatic compound comprising at least 16 carbon atoms per molecule. Aliphatic compounds suitable for use as ignition agents in the present invention include, but are not limited to, linoleyl alcohol, linoleic acid, eleostearic acid, eleostearyl alcohol, ricinoleic alcohol, clupadonyl alcohol, clupadonic acid, or any combination thereof. In some embodiments, the ignition agent comprises a pyrophoric compound such as an oxidizable lower alkyl derivative of boron or zinc described by (R1)₃B, R1 R2 R3Al, and R4 R5Zn, where R1 is C1 to C3 alkyl group and R2 to R5 are C1 to C4 alkyl groups. In yet other embodiments, the ignition agent may comprise an aqueous colloidal suspension of metallic magnesium. The ignition agent may also comprise any combination of the foregoing as desired.

The in situ combustion process induces a number of physical and chemical changes the hydrocarbons favorable to the recovery of the hydrocarbons in place, allowing a much higher percentage of hydrocarbons to be produced via production wellbore 160 than would otherwise be possible. One of the favorable changes induced by the in situ combustion process is hydrocarbon upgrading, a process by which large hydrocarbon molecules are converted into smaller, more useful molecules by rearranging the chemical bonds of the original molecules. Upgrading the hydrocarbons not only produces a more valuable product, but it also enhances the viscosity and mobility of the hydrocarbons making them easier to recover. The second hydrocarbon mixture 52 may then be produced to storage or pipeline 162 via production wellbore 160.

The methods contemplated herein may further comprise the step of determining an optimal frequency or range of frequencies of the generated radio frequency radiation for heating the reservoir hydrocarbons. In certain embodiments, optimizing the radiation frequency involves determining maximum energy transfer to the hydrocarbons for a given energy output from the energy generator based on, in part, radiofrequency adsorption as a function of penetration depth. In this way, an optimal radiation frequency may be determined that maximizes energy transfer to the hydrocarbons for a given energy input.

In certain embodiments, one or more activators may be introduced to in situ hydrocarbon mixture 51 to enhance heating of in situ hydrocarbon mixture 51. As used herein, the term “activator” refers to any component which is capable of interacting with the generated radio frequency radiation to convert the generated radio frequency radiation to heat. In some cases, in situ hydrocarbon mixture 51 may not be susceptible to the desired level of energy absorption from the generated radio frequency radiation (e.g. if in situ hydrocarbon mixture 51 is primarily non-polar and thus fails to interact with the generated radio frequency radiation). In some cases, in situ hydrocarbon mixture 51 may already include polar molecules such as water, asphaltenes, or other polar components. Asphaltenes, which are molecules with a range of chemical compositions, are often characterized as polar, metal containing molecules. These traits make them exceptional candidates for coupling with radio frequency radiation. Polar components inherent to in situ hydrocarbon mixture may be sufficient to render in situ hydrocarbon mixture 51 susceptible to a desired level of heating from the generated radio frequency radiation. Where in situ hydrocarbon mixture 51 fails to heat sufficiently upon interaction with the generated radio frequency radiation, one or more activators may be introduced to in situ hydrocarbon mixture 51. Activators may include ionic liquids, and may include metal ion salts and may be aqueous. Asymmetrical compounds generally provide more efficient coupling with the radio frequency radiation than symmetrical compounds. Other examples of activators suitable use with the methods described herein include, but are not limited to, inorganic anions such as halides. In certain embodiments, the activator comprises a metal containing compound such as those from period 3 or period 4 of the Periodic Table. In other embodiments, the activator comprises a halide of Na, Al, Fe, Ni, or Zn, including AlCl₄⁻, FeCl4⁻, NiCl₃⁻, ZnCl₃⁻, and combinations thereof. Other suitable activators include transitional metal compounds or organometallic complexes.

In one embodiment the added activator chosen would be a substance not already prevalent in the hydrocarbons. Substances that exhibit dipole motion that are already in the formation include water, salt, asphaltenes and other polar molecules. By injecting an activator not naturally present in the system, it not only permits the operator to establish the exact non-microwave frequency required to activate the activator, but also permits the operator the knowledge of how to eliminate the activator afterwards.

Methods of eliminating activators include chelation, adsorption, crystallization, distillation, evaporation, flocculation, filtration, precipitation, sieving, sedimentation and other known separation methods. All these methods are enhanced when one skilled in the art are able to ascertain the exact chemical that one is attempting to separate from the mixture. In certain embodiments, a factor influencing the selection of the activator is the ease with which the activator may be separated from the produced hydrocarbon mixture.

One may also be able to select a specific activator that does not need to be eliminated from the solution. One such example of an activator that can remain in crude oil includes activated carbon or graphite particles.

In certain embodiments, a predetermined amount of activators, comprising metal ion salts, are injected into the production well via a solution. Energy generators are then operated to generate radio frequency radiation capable of causing optimal excitation of the activators.

Activators may also include synthetic particles which may be “tuned” to desired optimal excitation frequencies. Examples of such synthetic particles include metal shell particles with dielectric material therein such that the synthetic particles are susceptible to a narrow range of excitation frequencies. Such synthetic particles may be especially desirable in certain embodiments due, in part, to the ease of separation of the synthetic particles from the produced hydrocarbons.

Turning to FIG. 3 (where like reference numerals refer to like elements corresponding to FIG. 2), an example of an enhanced hydrocarbon recovery system, here, shown with a plurality of activators introduced into hydrocarbon reservoir 107. Here, first activators 132 and second activators 134 have been introduced throughout the near wellborn region of hydrocarbon, each activator having a different optimal excitation frequency. The use of activators with differing optimal excitation frequencies allows for more fine tuned control of radio frequency heating of in situ hydrocarbon mixture 51. These differing optimal excitation frequencies allow an operator the option of exciting only a portion of the total activators. Additionally, different activators may be introduced at different concentrations or to different regions of hydrocarbon reservoir 107. For example, a first activator could be limited to the near well bore region while a second activator could be introduced to a different region of hydrocarbon reservoir 107. Thus, a plurality of activators, each with different optimal excitation frequencies affords an operator the flexibility of fine tuned control of radio frequency heating of in situ hydrocarbon mixture in a way that facilitates management of the in situ combustion process. Some embodiments may benefit from a varying frequency input to facilitate management of the in situ combustion process.

Although the examples depict one injection well and one production well, it is understood that the methods described herein could be applied to any number of injection and/or production wells, including typical circular drive patterns such as the five-spot, seven-spot, and nine-spot patterns. In certain embodiments, it may be desired to a single well for both injection (e.g. air injection and introduction of radio frequency radiation) and hydrocarbon production. Further, it is recognized that the term “mixture” as used herein also refers to non-homogeneous mixtures.

It is recognized that any of the elements and features of each of the devices described herein are capable of use with any of the other devices described herein without limitation. Furthermore, it is recognized that the steps of the methods herein may be performed in any order except unless explicitly stated otherwise or inherently required otherwise by the particular method.

Therefore, the present invention is well adapted to attain the ends and advantages mentioned as well as those that are inherent therein. The particular embodiments disclosed above are illustrative only, as the present invention may be modified and practiced in different but equivalent manners apparent to those skilled in the art having the benefit of the teachings herein. Furthermore, no limitations are intended to the details of construction or design herein shown, other than as described in the claims below. It is therefore evident that the particular illustrative embodiments disclosed above may be altered or modified and all such variations and equivalents are considered within the scope and spirit of the present invention. Also, the terms in the claims have their plain, ordinary meaning unless otherwise explicitly and clearly defined by the patentee.

Claims

1. A method for facilitating in-situ combustion of an in-situ hydrocarbon mixture using a generated radio frequency radiation comprising the steps of:

introducing one or more activators into a subterranean formation;

introducing the generated radio frequency radiation into the subterranean formation, wherein the generated radio frequency radiation is from about 0.1 MHz to about 1 GHz;

introducing an ignition agent into the subterranean formation;

allowing the generated radio frequency radiation to heat the one or more activators;

allowing the activators to heat the in-situ hydrocarbons by conductive heating to a first temperature that is supportive of auto-ignition of the in-situ hydrocarbon mixture, wherein the generated radio frequency radiation is from about 0.1 MHz to about 1 GHz;

introducing an oxidant into the subterranean formation to form a combined mixture of oxidant and in-situ hydrocarbon mixture;

allowing the combined mixture of the oxidant and the in-situ hydrocarbon mixture to auto-ignite; and

allowing the combined mixture to combust through a combustion process to form a second in-situ hydrocarbon mixture.

2. The method of claim 1 wherein the one or more activators is a metal containing compound from period 3 or period 4 of the Periodic Table, a halide of Na, Al, Fe, Ni, or Zn, including AlCl4−, FeCl4−, NiCl3−, ZnCl3−, transitional metal compounds, organometallic complexes, or any combination thereof.

3. The method of claim 1 wherein the one or more activators comprise a first activator and a second activator wherein the first activator has a first optimal excitation frequency and wherein the second activator has a second optimal excitation frequency.

4. The method of claim 3 wherein the generated radio frequency radiation comprises the first optimal excitation frequency and the second optimal excitation frequency.

5. The method of claim 3 wherein the generated radio frequency radiation varies in frequency through a frequency range that includes both the first optimal excitation frequency and the second optimal excitation frequency.

6. The method of claim 1 wherein the ignition agent is tung oil, linseed oil, red oil, castor oil, turpentine, tall oil, a fatty acid of tall oil, oleic acid, a fatty acid of linseed oil, diesel oil, magnesium powder, light naptha, any combination thereof.

7. The method of claim 1 wherein the ignition agent comprises a combustion catalyst wherein the combustion catalyst is cobalt naphthenate, cobalt tallate, cobalt octoate, or any combination thereof.

8. The method of claim 1 wherein the ignition agent comprises an aliphatic compound that comprises at least 16 carbon atoms per molecule.

9. The method of claim 8 wherein the aliphatic compound is linoleyl alcohol, linoleic acid, eleostearic acid, eleostearyl alcohol, ricinoleic alcohol, clupadonyl alcohol, clupadonic acid, or any combination thereof.

10. The method of claim 1 wherein the ignition agent is a pyrophoric compound wherein the pyrophoric compound is an oxidizable lower alkyl derivatives of boron or zinc described by (R1)3B, R1 R2 R3Al, and R4 R5Zn, where R1 is C1 to C3 alkyl group and R2 to R5 are C1 to C4 alkyl groups.

11. The method of claim 1 wherein the ignition agent is an aqueous colloidal suspension of metallic magnesium.

12. A method for facilitating in-situ combustion of an in-situ hydrocarbon mixture using a generated radio frequency radiation comprising the steps of:

introducing the generated radio frequency radiation into a subterranean formation;

allowing the generated radio frequency radiation to heat one or more components of the in-situ hydrocarbon mixture to a first temperature that is supportive of auto-ignition of the in-situ hydrocarbon mixture, wherein the generated radio frequency radiation is from about 0.1 MHz to about 1 GHz;

introducing an ignition agent into the subterranean formation;

introducing an oxidant into the subterranean formation to form a combined mixture of oxidant and in-situ hydrocarbon mixture;

allowing the combined mixture of the oxidant and the in-situ hydrocarbon mixture to auto-ignite; and

allowing the combined mixture to combust through a combustion process to form a second in-situ hydrocarbon mixture.

13. The method of claim 12 wherein the generated radio frequency radiation is from about 300 MHz to about 1 GHz.

14. The method of claim 12 wherein the oxidant is air, an oxygen-enriched mixture, a gas mixture comprising oxygen, or any combination thereof.

15. The method of claim 12 further comprising the step of upgrading a plurality of the components of the in-situ hydrocarbon mixture.

16. The method of claim 12 wherein the in-situ hydrocarbon mixture has a first viscosity and wherein the second in-situ hydrocarbon mixture has a second viscosity, and wherein the method of claim 12 further comprises the step of allowing the combustion process to produce the second in-situ hydrocarbon mixture with a second viscosity that is lower than the first viscosity.

17. The method of claim 12 further comprising the step of producing a portion of the second hydrocarbon mixture.

18. The method of claim 12 further comprising the step of introducing an upgrading catalyst into the subterranean formation before the step of allowing the combined mixture of oxidant and the in-situ hydrocarbon mixture to auto-ignite.

19. The method of claim 13 wherein the step of introducing the generated radio frequency radiation into the subterranean formation occurs at a second well and wherein the step of producing the portion of the second hydrocarbon mixture occurs at a first well.

20. The method of claim 12 further comprising the step of determining an optimal frequency for the generated radio frequency radiation to achieve the auto-ignition temperature of the combined mixture, wherein the optimal frequency maximizes overall heat input to the in-situ hydrocarbon mixture, wherein the generated radio frequency radiation is within about 10% of the optimal frequency.

21. The method of claim 12 wherein the in-situ hydrocarbon mixture and the second hydrocarbon mixture are each non-homogenous mixtures.

22. The method of claim 12 further comprising the step of introducing a second generated radio frequency radiation into the subterranean formation, after the step of allowing the combined mixture to combust, to maintain the combustion process.

23. The method of claim 12 wherein the ignition agent is tung oil, linseed oil, red oil, castor oil, turpentine, tall oil, a fatty acid of tall oil, oleic acid, a fatty acid of linseed oil, diesel oil, magnesium powder, light naptha, any combination thereof.

24. The method of claim 12 wherein the ignition agent comprises a combustion catalyst wherein the combustion catalyst is cobalt naphthenate, cobalt tallate, cobalt octoate, or any combination thereof.

25. The method of claim 12 wherein the ignition agent is an aliphatic compound comprising at least 16 carbon atoms per molecule.

26. The method of claim 25 wherein the aliphatic compound is linoleyl alcohol, linoleic acid, eleostearic acid, eleostearyl alcohol, ricinoleic alcohol, clupadonyl alcohol, clupadonic acid, or any combination thereof.

27. The method of claim 12 wherein the ignition agent is a pyrophoric compound wherein the pyrophoric compound is an oxidizable lower alkyl derivatives of boron or zinc described by (R1)3B, R1 R2 R3Al, and R4 R5Zn, where R1 is C1 to C3 alkyl group and R2 to R5 are C1 to C4 alkyl groups.

28. The method of claim 12 wherein the ignition agent is an aqueous colloidal suspension of metallic magnesium.