CA2647825C - Apparatus, methods, and systems for extracting petroleum and natural gas - Google Patents

Abstract

Apparatus, methods, and systems for recovering oil or natural gas from a petroleum reservoir. In one example, the method may include reforming a fuel source by reaction with water to generate driver gas, and injecting the driver gas into the oil well. The reforming operation may include combusting a combustible material with ambient oxygen to release energy, and heating a reforming reaction fuel and water sources, with the energy released from the combustion of the combustible material, to a temperature above that required for the reforming reaction, thereby the fuel and water sources are reformed into driver gas. The driver gas may include hydrogen and/or carbon dioxide gas that may be used to extract oil from the ground and especially oil from depleted oil wells. It may also be used to drive natural gas trapped underground or in coal beds to the surface. The reforming reaction fuel and/or the combustible material may be obtained from coal and/or a derivative of coal.

Description

APPARATUS, METHODS, AND SYSTEMS FOR EXTRACTING PETROLEUM AND
NATURAL GAS

REFENCE TO RELATED APPLICATIONS

[0001] This application is a PCT (Patent Cooperation Treaty) application, and claims priority from U.S. Serial No. 11/392,898 entitled "Apparatus and method for extracting petroleum from underground sites using reformed gases" to Robert Zubrin et al., filed on March 29, 2006.

FIELD OF THE INVENTION

[0002] This invention relates to the extraction of gasses and liquids from underground and underwater sites and more particularly to petroleum and/or natural gas extraction using reformed gas. More particularly, the present invention relates to a portable apparatus that may be taken to the location of a candidate oil field and used to extract oil and/or natural gas.

BACKGROUND OF THE INVENTION

[0003] Currently there are tens of thousands of depleted oil and natural gas wells around the world, which collectively possess significant amounts of petroleum resources that cannot currently be extracted using conventional extraction techniques.

[0004] For example, in a typical oil well, only about 30% of the underground oil is recovered during initial drilling ("primary recovery"). An additional approximately 20%
may be accessed by "secondary recovery" techniques such as water flooding. In recent years, "tertiary recovery"
(also known as "Enhanced Oil Recovery" or EOR) techniques have been developed to recover additional oil from depleted wells. Such tertiary recovery techniques include thermal recovery, chemical injection, and gas injection. Using current methods, these tertiary techniques allow for an additiona120% or more oil to be recovered.

[0005] Gas injection is one of the most common EOR techniques. In particular, carbon dioxide (C02) injection into depleted oil wells has received considerable attention owing to its ability to mix with crude oil. In cases where the crude oil is miscible with COz, injection of COz renders the oil substantially less viscous and more flowable. The remobilized oil can be recovered by traditional water flooding or other secondary recovery techniques. For extremely heavy oil compositions, COz flooding results in a reduction in the viscosity of the oil when the oil becomes saturated with COz. The reduced viscosity mobilizes the oil for recovery through fluid drive.

[0006] Despite the potential advantages of COz in enhanced recovery, its use has been hampered by several factors. For instance, in order for the enhanced recovery process to be economically viable, the COz gas must be naturally available in copious supplies at reasonable cost at or near the site of the oil well. Alternatively, COz can be produced from industrial applications such as natural gas processing, fertilizer, ethanol and hydrogen plants where naturally occurring COz reservoirs are not available. The COz can then be transported over large distances via pipeline and injected at the well site. Unfortunately, such COz pipelines are difficult and costly to construct. Additionally, many oil sites are out of reach from such natural and industrial sources of CO2.

[0007] Another gas that can potentially be used for enhanced recovery purposes is hydrogen.
Hydrogen has received considerably less attention than COz, however. Hydrogen, although slightly miscible with oil, is far less so than COz. Moreover, traditionally, hydrogen has been costly to produce and its use has not been justified from an economic standpoint.

[0008] Nonetheless, there are various properties of hydrogen that suggest it would be highly useful in tertiary oil recovery if it can be economically produced at the site of the oil well. For instance, hydrogen has an extremely high rate of diffusion and is able to pervade the underground reservoir relatively quickly upon injection. Thus, the hydrogen will cause the oil to swell leading to a subsequent reduction in viscosity. At the same time, hydrogen will pressurize the well by creating an artificial gas cap. The resultant increased pressure renders the oil more amenable to be withdrawn from the reservoir. Moreover, unlike water and heavier gases, hydrogen has the ability to invade tight junctions in a petroleum reservoir and thus may provide a driving force for moving the oil from such tight portions of a reservoir.

[0009] Another potentially significant advantage of using hydrogen in enhanced oil recovery is its ability to hydrogenate the oil in-situ. Hydrogenation of oil purifies the crude oil while at the same time reducing the viscosity of the oil, thus making the oil more prone to tertiary recovery.
Generally, the hydrogenation reactions to purify recovered crude oil are carried out following oil recovery. Such processing steps are costly and environmentally harmful.
Accordingly, the benefits of in-situ hydrogenation of oil reservoirs have long been recognized.
Yet, attempts to hydrogenate oil wells in-situ have not met with significant success, particularly from an economic standpoint. Lack of success can partially be attributed to the large concentrations of hydrogen that need be injected to obtain significant hydrogenation rates.
Also, it is generally believed that temperatures of the reservoir are too low for hydrogenation to proceed at a sufficient rate. Therefore, methods of heating the reservoir by processes such as in-situ combustion or steam soaking are used concurrently to keep the well at an elevated temperature.
There have been suggestions that hydrogenation can take place at reservoir temperatures without the need for simultaneous heating of the well as long as residence times are sufficiently long.

[0010] Accordingly, as recognized by the present inventors, what is needed is a novel method, apparatus, and system for extracting oil/petroleum from the ground or from oil wells, such as depleted oil wells. What is also needed is a method, apparatus, and system for extracting natural gas from the ground or from natural gas wells.

[0011] Therefore, it would be an advancement in the state of the art to provide an apparatus, system, and method for generating large quantities of carbon dioxide, hydrogen, and other gases at low cost at or near an oil site.

[0012] It is against this background that various embodiments of the present invention were developed.

BRIEF SUMMARY OF THE INVENTION

[0013] One embodiment of the present invention is a portable apparatus for generating a gas mixture that may be used to drive currently unrecoverable oil from a near-depleted, or depleted, oil reservoir. An embodiment of the present invention is a portable, highly economic COz generation system. An embodiment of the present invention also generates large supplies of hydrogen. An embodiment of the present invention is a portable, modular system which may be delivered to the site of the oil well by various methods of transportation, including a truck, a boat, or an airplane. The scale of the present invention is simultaneously portable and also sized to generate sufficient driver gas for economic recovery of oil.

[0014] In one embodiment of the present invention, the portable apparatus generates COz and hydrogen by a hydrogen reforming reaction. The COz is injected into the well while the hydrogen is split off from the COz product to be used for other purposes, including petrochemical generation or electrical power generation. As will be discussed below, the hydrogen can also be injected simultaneously with the COz. Depending upon factors such as the particular composition of the underground oil, as well as the local cost of electrical power, the user of the present invention may find it advantageous to use hydrogen in different proportions for these various purposes. Furthermore, the hydrogen may be injected by itself while the COz is used for other purposes.

[0015] In one embodiment of the present invention, pressurized hydrogen and COz are injected simultaneously into the well. Carbon dioxide, when combined with hydrogen, is expected to have a greater impact on enhanced oil recovery than COz alone. Carbon dioxide, by virtue of dissolving in the crude oil, will decrease the viscosity of the oil, making it more flowable. In turn, the rate of hydrogenation will be enhanced by decreasing the activation energy necessary to drive the reaction forward. Additionally, by permeating the small nooks and crevices in the bedrock, the hydrogen will expose more of the oil to carbon dioxide gas. Thus, carbon dioxide and hydrogen are expected to have a cooperative and mutually beneficial effect on the oil recovery process.

[0016] Thus it may be seen that carbon dioxide and hydrogen, working alone or in combination, have unique properties that can be applied to the problems of improved recovery of crude oil. It will be appreciated that this invention is not limited to this particular theory of operation, but that any theory that has been advanced is merely to facilitate disclosure and understanding of the invention.

[0017] It is another embodiment of the present invention to inject gases that are miscible in oil into an oil well in order to generate an artificial gas cap, thereby enhancing recovery of the oil. It is another embodiment of the present invention to inject a gas mixture composed of hydrogen and other gases so that the gas cap is a mixture composed substantially of hydrogen. It is another embodiment of the present invention to inject a gas mixture composed of carbon dioxide and other gases so that the gas cap is a mixture composed substantially of carbon dioxide. It is another embodiment of the present invention to inject a gas mixture composed substantially of hydrogen and carbon dioxide so that the gas cap is a mixture composed substantially of hydrogen and carbon dioxide. It is another embodiment of the present invention to capture the mixture of gases emerging from the oil well, composed substantially of carbon dioxide and hydrogen, apart from the recovery of crude oil.

[0018] In light of the above and according to one embodiment of the present invention, disclosed herein is a method for generating and using hydrogen and carbon dioxide gas mixtures for driving oil from an oil well. In addition, and in accordance with another embodiment of the present invention, disclosed herein is a method for generating and using hydrogen and carbon dioxide gas mixtures for driving trapped natural gas out of the ground.

[0019] In one example, the methods of the invention include reforming or reacting a fuel or other hydrocarbon source with water to generate hydrogen and carbon dioxide "driver gas" mixtures and injecting the driver gas into the oil well. The fuel or hydrocarbon sources used for generation of driver gas include, but are not limited to, alcohols, olefins, paraffins, ethers, aromatic hydrocarbons, solid hydrocarbons (such as coal), and the like. In addition, the fuel sources can be from refined commercial products such as propane, diesel fuels, gasolines or unrefined commercial products such as crude oil, natural gas, or solid hydrocarbons (such as coal). The water can be introduced into the reforming reactor as liquid water, as steam, or, if the fuel is an alcohol or other substance miscible in water, as a component premixed with the fuel.

[0020] In other embodiments the fuel source for the reforming reaction is an unrefined product such as crude oil, and in some embodiments, a crude oil captured from the same oil well where the driver gas is being injected.

[0021] The reforming reaction can be driven by the release of energy from a combustible or non-combustible source (such as electricity). In other embodiments, the energy is provided by a combustion reaction using a combustible material and atmospheric air.

[0022] In other embodiments the driver gas is a hydrogen-rich gas mixture.

[0023] The method may also include the addition of a catalyst to the reforming reaction. The catalyst reduces the temperature required to reform the fuel source.

[0024] According to another embodiment of the present invention, disclosed herein is an apparatus for removing oil from an oil well. In one example, the apparatus may include a first storage container for storing a combustible material used in the combustion reaction; a second storage container for storing a fuel or alternative hydrocarbon source used in the reforming reaction; a third storage container for water to be reacted with fuel in the reformer; a first chamber having an inlet and an outlet, the first chamber for combusting the combustible material with ambient oxygen for the release of energy, the inlet of the first chamber fluidly coupled with the first storage container; and a second chamber having an inlet and an outlet, the inlet of the second chamber fluidly coupled with the second and third storage containers, a portion of the second chamber positioned within a portion of the first chamber, the second chamber fluidly isolated from the first chamber. In one example, the energy released in the first chamber heats the fuel and water sources used in the reforming reaction in the second chamber to a temperature above that necessary for the reforming reaction, thereby reforming the fuel and water sources into driver gas exiting the outlet of the second chamber.

[0025] In one example, the first chamber includes an igniter for igniting the combustible material, and the second storage container may include a mixture of water with the reforming reaction fuel source. The second chamber may be adapted to receive a catalyst to reduce the temperature and amount of energy required to heat the reforming reaction fuel and water sources to a temperature above that necessary for the reforming reaction to proceed.

[0026] In another embodiment, the apparatus may include a first heat exchanger coupled with the outlet of the first chamber and thermodynamically coupled with the second chamber, the first heat exchanger for pre-heating the reforming reaction fuel and/or water sources. The apparatus may also include a second heat exchanger coupled with the outlet of the second chamber and thermodynamically coupled with the inlet of the second chamber, the second heat exchanger for pre-heating the reforming reaction fuel and or water sources and for cooling the generated driver gas.

[0027] According to another embodiment of the present invention, disclosed herein is an autothermal apparatus for generating driver gas to remove oil from an oil well. In one example, the apparatus may include a single reaction chamber for combining a reforming fuel source, water, and an oxidizer; a reforming reaction fuel delivery pipe for delivery of the reforming fuel source; another pipeline for water; an oxidizing agent delivery pipe for delivery of oxygen or other oxidizing agent; and a driver gas outlet port for removal of driver gas produced in the reaction chamber. In one example, a counter-flow heat exchanger provides energy/heat from the released driver gas to the incoming reformer fuel to facilitate the autothermal reformer reaction in the reaction chamber.

[0028] In one example of the autothermal reformer apparatus, a reaction chamber heater pre-heats the reaction chamber to initiate the reforming reaction and subsequent formation of driver gas. In another example, the reaction chamber includes a catalyst bed to facilitate autothermal reforming of appropriate reforming fuel sources.

[0029] The features, utilities and advantages of the various embodiments of the invention will be apparent from the following more particular description of embodiments of the invention as illustrated in the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 illustrates an example of an embodiment of the present invention for the extraction of oil from an oil well, in accordance with an embodiment of the present invention.

[0031] Figure 2 illustrates an example of operations for extracting oil from an oil well, in accordance with an embodiment of the present invention.

[0032] Figure 3 illustrates an example of an apparatus for extracting oil from an oil well, in accordance with an embodiment of the present invention.

[0033] Figure 4 illustrates another example of an apparatus for extracting oil from an oil well, in accordance with an embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0034] Embodiments of the present invention provide for the creation of driver gas which is used for extracting oil from an otherwise depleted oil well, or to drive trapped reservoirs of underground natural gas to the surface. For purposes of the present invention, a driver gas is typically any gas formed during the reforming reactions of the present invention and is preferably a hydrogen-rich gas or hydrogen and carbon dioxide containing gas.
Various embodiments of the present invention are disclosed herein. Note that the majority of the disclosure is directed toward creating a driver gas that is ultimately injected into depleted oil wells for the extraction of oil; however, methods and apparatus of the invention can also be used to create driver gases useful in driving trapped natural gas to the surface.
As such, it is noted that the scope of the present invention encompasses the use of driver gas created in accordance with the present invention to drive out other materials beyond oil from depleted oil wells, and in particular encompasses using driver gas to drive trapped natural gas out of underground natural gas reservoirs.

[0035] In Fig. 1, a below-ground oil well 100 (which may be otherwise depleted) is illustrated, having an amount of oil therein, such as a residual amount of oil. A portable, self-contained reformer 102 in accordance with the present invention generates driver gas (shown as arrow 104) which may be pumped into the oil well for removing the residual oil from the oil well. As explained herein, the reformer 102 may reform or react fuel sources (shown as arrow 105) such as alcohols, olefins, paraffins, ethers, aromatic hydrocarbons, and other like materials (or mixtures thereof) with (shown as arrow 107) (or without) water to form driver gas which, in one example, is hydrogen and carbon dioxide gas mixture. The driver gas is then compressed by a compressor 106 into high pressure gas that could be pumped underground (see line 108) where it could impose pressure on residual underground petroleum 109 sufficient to allow it to be extracted by a nearby oil well 110 or other like site.

[0036] Fig. 2 illustrates an example of operations which may be performed in order to drive petroleum resources out of the ground, such as out of an oil well or a depleted oil well. At operation 1(shown as box 200), a fuel source is reformed into driver gas. In one example, operation 1 may include combustion of a materia1202 such as methanol or ethanol, in order to provide energy, for instance, within a combustion chamber. The energy generated from the combustion may be used to heat the reforming reaction fuel source to a temperature where the fuel source reacts with (or without) water to form a hydrogen-rich driver gas 204. Note that the energy used to drive the reforming reaction can also be provided from a non-combustible source, for example, solar energy, nuclear energy, wind energy, grid electricity, or hydroelectric power (shown as box 206).

[0037] At operation 2 (shown as box 208), the driver gas is injected into the oil well in order to drive petroleum out of the ground 210. For instance, the injected gas may soften highly viscous petroleum residues and displace them, thereby mobilizing such petroleum residues for recovery by conventional means (shown as box 212).

[0038] Embodiments of the present invention provide reformer apparatus for generating driver gas used in petroleum extraction, from among other sites, depleted oil wells.
Apparatus embodiments of the invention are portable, self-contained, and energy efficient, and are able to generate driver gas through reforming of a fuel source. In some embodiments, the apparatus utilizes a reforming reaction to generate the driver gas and a combustion reaction to provide the energy required to reform a fuel and generate the driver gas. Various apparatus embodiments are provided herein based on either separating the reforming reaction from the combustion reaction or based on combining the reforming reaction with the combustion reaction (referred to herein as autothermal reforming). In addition, the apparatus typically includes heat exchange elements to facilitate heat transfer from the high temperature driver gas to incoming reformer and/or combustion fuel. The transfer of heat facilitates the reforming reaction and lowers the energy required to complete the driver gas formation. Note that various apparatus configurations are envisioned to be within the scope of the present invention as long as the apparatus provides for on-site, portable, energy efficient reforming reactions (and preferably steam reforming reactions) that produce driver gas useful in the extraction of petroleum products from an underground source. As such, one illustrative embodiment is described in Fig. 3 for separate reformer and combustion reactions, followed by an embodiment described in Fig. 4 for autothermal reforming and production of driver gas from a single reaction chamber.

REFORMER APPARATUS

[0039] Fig. 3 illustrates an example of a self-contained, portable apparatus 300 for generating driver gas (shown as arrow 302) for injection into the ground or an oil well, in accordance with one embodiment of the present invention.

[0040] In Fig. 3, an embodiment of the apparatus may include a first storage container 304 storing a combustible material, such as an alcohol or olefin. A second storage container 306 is also provided, which may include a reforming reaction fuel source, such as an alcohol, olefin, paraffin, and the like or mixtures thereof. If the reformer fuel is an alcohol or other chemical miscible in water, the water may be mixed with the fuel in this container. If the reformer fuel is a hydrocarbon such as a paraffin not miscible in water, a third container (not shown) is used for the water to be reacted with the fuel in the reformer chamber.

[0041] In one example, a first chamber 304 has an inlet port 308 and an outlet port 310 and is adapted to provide for the combustion of the combustible material. In one example, the first chamber includes an igniter such as a spark plug 312 or other conventional igniter, and a nozzle 314 coupled with the inlet port 308 of the first chamber 304. The inlet port 308 of the first chamber may be coupled with the first storage container so that the contents of the first storage container may be introduced into and combusted within the first chamber. The first chamber also includes a port 316 for introducing combustion air into the first chamber. The first chamber is also adapted to receive a portion of the second chamber 306, described below, so that the energy/heat from the combustion of the combustible material from the first storage container within the first chamber is transferred into a portion of the second chamber.
The outlet port 310 of the first chamber, in one example, is near the inlet port of the second chamber (not shown), and a heat exchanger is used to allow the combustion exhaust gas to heat the fuel and water entering the second chamber. Alternatively, the outlet of the first chamber can feed to a heat exchanger 318 located inside the second chamber, which thereby allows the combustion exhaust gases produced in the first chamber to provide the heat to drive the reforming reactions in the second chamber.

[0042] The second chamber 306 has an inlet port (shown as arrow 320) and an outlet port 302.
In one example, the inlet port is coupled with the second storage container and receives the contents of the second and third storage containers. The second chamber may also include a port 322 for receiving catalyst material within the second chamber.

[0043] In one example, the second chamber is positioned within the first chamber, such that the combustion heat/energy from the first chamber heats the reforming reaction fuel and water sources contained within the second chamber to a point where the fuel source vaporizes and reforms into a driver gas which exists out of the outlet port of the second chamber. In one example, the first and second chambers are fluidly isolated.

[0044] A catalyst 324 may be utilized within the second chamber in order to reduce the temperature and amount of energy required to heat the reforming reaction fuel and water sources to their reaction temperature and such catalysts are dependent upon the fuel source but include iron based catalyst, zinc oxide, copper based catalyst, alumina, and the like.

[0045] In one example, a first heat exchanger 318 is coupled with the outlet port of the first chamber (the combustion chamber) and is thermodynamically coupled with a portion of the inlet port of the second chamber. In this manner, the hot combustion exhaust gases from the first chamber are used to preheat the reforming reaction fuel and/or water sources as they are being introduced into the second chamber for vaporization/reformation into a driver gas.

[0046] A second heat exchanger 326 may also be utilized, wherein the second heat exchanger 326 is thermodynamically coupled with the outlet port 302 and the inlet port 320 of the second chamber, which provides the dual benefit of preheating the reforming reaction fuel and/or water sources prior to entry into the second chamber, as well as cooling the driver gas which is expelled from the outlet ports of the second chamber. Note that various illustrative temperatures are shown to illustrate heat-exchange, but are not meant to limit the range of temperatures useful in the present invention.

[0047] Not withstanding the above examples, the present invention does not require the use of heat exchangers. The use of heat exchangers is strictly optional. Heat exchangers may be used to increase the efficiency of the reformer apparatus. However, there may be situations in which heat exchangers would not be used, such as when hot driver gas is desired and/or when the reaction fuel and/or water sources are pre-heated.

AUTOTHERMAL APPARATUS

[0048] Fig. 4 illustrates another example of a self-contained portable apparatus 400 for generating driver gas for injection into the ground or an oil well, in accordance with another embodiment of the present invention. The embodiment illustrated in Fig. 4 provides an "autothermal reformer" for the production of driver gas which is injected into the ground or an oil well (to remove oil or natural gas or other like materials).

[0049] An autothermal reformer 400 of the present invention directly reacts a reformer fuel source with oxygen or other oxidizers in a single chamber 402. Embodiments of the reformer provide an environment for reforming a fuel source from a feed at proper temperature and pressure resulting in the release of driver gas. Since the reforming reaction is favored by low pressure, in some embodiments, pressure in the autothermal reactor is maintained under 50 bar.
Embodiments of the autothermal reformer combine counter-flow heat exchange elements to enhance heat transfer and energy efficiency of the autothermal reformer.

[0050] Fig. 4 shows one embodiment of the autothermal reformer apparatus 400 of the present invention. Note that other autothermal reformer apparatus are envisioned to be within the scope of the present invention as long as they provide at least a reaction chamber with a reforming reaction fuel source inlet, an air or oxidizing agent inlet, and a driver gas outlet.

[0051] Referring to Fig. 4, an autothermal reformer apparatus 400 is shown having a reaction chamber 402, a reforming reaction fuel delivery pipe (fuel pipe) 404 for delivery of a reforming reaction fuel, a driver gas outlet port (outlet port) 406 for release of produced driver gas, and an oxygen or other oxidizing gas inlet pipe (gas pipe) 408 for delivery of an oxidizing gas used in the combustion of the reforming reaction fuel in the reaction chamber.

[0052] Still referring to Fig. 4, the reaction chamber 402 is of sufficient size and shape for autothermal reforming of a fuel source. Different chamber geometries can be used as long as they constrain the autothermal reforming reactions of the present invention and provide sufficient chamber space to produce an amount of driver gas necessary at an oil extraction site. A catalyst bed (see below) 410 is typically integrated into the reaction chamber for optimized autothermal reforming reactions. In the embodiment shown in Fig. 4, the fuel pipe 404 is coupled to the outlet port to form a counter-exchange heat exchanger 412 so that the energy/heat from the exiting driver gas is transferred to the reforming fuel entering the reaction chamber via the fuel pipe. In addition, the fuel pipe 404 typically enters at a first or top end 414 of the reaction chamber and releases the fuel toward the second or bottom end 416 of the reaction chamber.
This configuration enhances heat release from the heated reformer fuel into the contents of the reaction chamber. Release of fuel into the chamber 402 can be via a nozzle 415 or other like device. The gas pipe 408 is typically coupled to or adjacent to the fuel pipe and releases the oxygen or other oxidizing gas adjacent to the release of the reformer fue1417.
Note that other configurations of reformer fuel and water delivery, oxygen or other oxidizing agent delivery, and driver gas release are envisioned to be within the scope of the invention and are shown in Fig. 4 as an illustration of merely one embodiment.

[0053] When in use, the reaction chamber of the autothermal reformer apparatus is typically preheated to a temperature sufficient to start the reforming reaction, i.e., between approximately 200 C - 400 C. Preheating may be accomplished by a reaction chamber integrated heating element, a heating coil, an external combustor heating system, or other like device (not shown).

[0054] The reformer fuel source (with or without water, see below) is fed into the reaction chamber via the fuel pipe 404. Note that once driver gas is produced in the reaction chamber, the reformer fuel is heated prior to delivery into the reaction chamber by the exiting driver gas (shown as arrow 418) via the counter-flow heat exchanger. At approximately the same time that the reformer fuel is being delivered to the reaction chamber, the oxygen or other oxidizing agent is being delivered to the reaction chamber via the inlet pipe. Various reformer chemical reactions are described below.

[0055] Once the reforming reaction has been established within the reaction chamber, the reaction chamber heating element may be shut off to conserve energy. Note also that the amount of water combined into the reforming fuel can be adjusted to control the reforming temperatures.

CHEMICAL PROCESSES

[0056] The generation of driver gas(es) will now be described, for example generating driver gas, i.e., a mixture of hydrogen (Hz), carbon monoxide (CO), and/or carbon dioxide (C02). The constituents of driver gas produced by embodiments of the present invention is determined by the reaction constituents and conditions as described below, but generally may include hydrogen gas, carbon dioxide gas, and mixtures thereof.

[0057] Embodiments of the present invention provide processes for producing driver gas from the reforming of select fuel sources, such as solid, liquid and/or gaseous hydrocarbons, alcohols, olefins, paraffins, ethers, and other like materials. Illustrative fuel sources for use in the reforming reaction include, but are not limited to, methanol, ethanol, propane, propylene, toluene and octane.

[0058] The combustor fuel can include both refined commercial products such as propane, diesel fuel, and/or gasoline, or unrefined substances such as crude oil, natural gas, coal, or wood. In some embodiments, the driver gas mixture is generated from the steam reforming of fuels such as methanol or ethanol. In other embodiments, the driver gas is generated by reforming unrefined hydrocarbon sources such as crude oil, especially crude oil obtained from the oil well site where the driver gas is being injected.

[0059] In other embodiments, the driver gas is generated by reforming solid hydrocarbons, such as coal, which could be lignite, sub-biturminous, biturminous, anthracite, peat, and the like. The solid hydrocarbons may be used for the reforming reaction fuel, the combustion reaction fuel, or both. One advantage of utilizing solid hydrocarbons is the relatively low price of coal and other solid hydrocarbons as compared to many liquid and gaseous fuels.

[0060] The methods of the present invention are reproducible and easily performed in the portable inventive devices described herein. The processes of the present invention are superior to electrolytic hydrogen generation which require large amounts of electrical power and are typically non-portable. The processes of the present invention are also superior to the production of hydrogen by cracking or pyrolyzation of hydrocarbons without the use of water because much more driver gas is produced for a given amount of fuel consumed.

[0061] The methods of the present invention use easily obtained fuel sources such as a hydrocarbon sources, water, and atmospheric air.

[0062] Embodiments of the invention also include combustible materials to supply the energy to drive the reforming reactions of the present invention. Combustible reactions can include a source of energy that is burned with ambient oxygen for the release of energy.
Note that in alternative embodiments of the present invention, the energy used to drive the reforming reactions of the invention may be provided by non-combustion sources, such as solar, nuclear, wind, grid electricity, or hydroelectric power.

[0063] In some embodiments of the present invention, the reforming reaction to generate driver gas and combustion reactions to drive that reaction both incorporate the same fuel. For example, methanol may be used as the reforming fuel source and as the source of combustion to drive the reforming reaction. Alternatively, coal may be used both as the reforming fuel source and as the source of combustion to drive the reforming reaction.

[0064] In more detail, the present invention provides reforming processes of any reforming fuel source to generate, for example, H2, CO, and/or COz gases. The driver gas forming reactions of the present invention are endothermic, requiring an input of energy to drive the reaction toward fuel reformation.

[0065] In one embodiment, the energy required to drive the reforming reaction is provided through the combustion of any combustible material, for example an alcohol, a refined petroleum product, crude petroleum, natural gas, wood, or coal that provides the necessary heat to drive the endothermic steam reforming reaction.

[0066] In another embodiment, the energy required to drive the reforming reaction is provided via any non-combustible source sufficient to generate enough heat to drive the reforming reaction to substantial completion. Examples of non-combustible sources include solar, nuclear, wind, grid electricity, or hydroelectric power.

[0067] The present combination of reforming and combustion reactions can be performed within a portable reaction vessel, for example the devices described herein (see Fig.
3 and Fig. 4). This is in contrast to electrolytic hydrogen gas formation, which requires large amounts of electrical power and non-portable machinery for the generation of the gas.

[0068] The following reactions provide illustrative processes for reforming a fuel source to produce a driver gas used in the recovery of oil or other like materials.
Several illustrative combustion reactions that provide the energy required to drive those reforming reactions are also provided. In one embodiment, provided as Reaction 1, a hydrogen-rich driver gas is formed using pure methanol. Note that the reforming reaction and combustion reaction can be performed in separate reaction chambers (see Fig. 3) or can be combined and performed in a single reaction chamber (see Fig. 4). The following 12 reactions illustrate a separation of the reforming and combustion reactions, however, as is shown in Fig. 4 and discussed in greater detail below, an autothermal reforming reaction can be accomplished by directly reacting the fuel sources of the present invention with oxygen in a single reaction chamber. Importantly, these autothermal reactions may be performed in the presence or absence of water.

[0069] Separate chamber reactions (see Fig. 3):

[0070] Reaction 1: CH3OH --> CO + 2H2 [0071] Reaction 1 comes with an AH of +128.6 kJoules/mole. This means that this same amount of energy should be contributed by the combustion reaction to drive the reaction toward the formation of CO and H2.

[0072] In an alternative embodiment, the reformed fuel, e.g., methanol, can be mixed with water as shown in reaction 2:

[0073] Reaction 2: CH3OH + HzO(e) -> COz + 3H2 [0074] Reaction 2 comes with an AH of + 131.4 kJoules/mole. As shown above in Reactions 1 and 2, for a small price in energy, an appropriate fuel source can be cracked to form hydrogen, carbon monoxide, and carbon dioxide. By comparing Reaction 2 to Reaction 1, observe that for essentially the same energy, the use of water allows the hydrogen yield to be increased by 50%.
This is why it is generally advantageous to employ both water and fuel in the proposed reforming reactions.

[0075] Reactions 3-9 illustrate several other reforming reactions that are in accordance with the present invention.

[0076] Reaction 3 (ethanol): CzHSOH + 3H20 --> 2C02 + 6H2 [0077] Reaction 4 (propane): C3Hg + 6H20 -> 3C02 + 10H2 [0078] Reaction 5 (propylene): C3H6 + 6H20 -> 3C02 + 9H2 [0079] Reaction 6 (toluene): C7Hg + 14H20 ~ 7C02 + 18H2 [0080] Reaction 7 (octane): CgHig + 16H20 ~ 8C02 + 25H2 [0081] Reaction 8 (methane): CH4 + 2H20 -> COz + 4H2 [0082] Reaction 9 (coal): C + 2H20 -> COz + 2H2 [0083] Note that in general Reactions 1-9 (as well as other reforming reactions of the present invention) result in large increases in the number of molecules of products compared to reactants, so all are benefited by being performed under low pressure.

[0084] In alternative embodiments, the reforming reaction is performed in the presence of a catalyst, for example, when the reforming reaction fuel is an alcohol, e.g., methanol or ethanol, which is combined with water, the feed is passed over a copper on alumina, copper on zinc oxide, or other copper-based catalyst at temperatures above 250 C (although better results may be obtained at higher temperatures). Thus, for example, the reactor chamber in Fig. 4 could be prepared with a copper on zinc oxide catalyst when the reformer fuel is an alcohol.

[0085] When the reforming reaction fuel is a hydrocarbon, e.g., paraffins, olefins, aromatics, combined with water, the feed is passed over an iron based catalyst at temperatures above 300 C
(although better results may be obtained at higher temperatures).

[0086] When the reforming reaction fuel is methane combined with water, the feed is passed over a nickel or ruthenium based catalyst at temperatures above 500 C
(although better results may be obtained at higher temperatures).

[0087] In some embodiments, combinations of olefins, paraffins, and aromatics (as found in crude petroleum) can be used as the reforming reaction fuel source. In other embodiments, a crude petroleum product is used as the reforming reaction fuel source where the crude petroleum product is first treated to remove sulfur or other impurities (sulfur can poison catalyst involved with the reforming reaction). Note that other reforming reaction fuel sources may also be pre-treated for removal or sulfur or other impurities, for example, natural gas.

[0088] In another embodiment of the present invention, a reforming reaction fuel source can be generated from a pre-source. In one example, gamma alumina is used to react dimethyl ether with water to make methanol via Reaction 10:

[0089] Reaction 10: (CH3)20 + H20 --> 2CH3OH

[0090] The methanol produced in Reaction 10 can then be reacted with more water via Reaction 2 to produce the driver gas used to obtain oil from depleted oil wells, for example. As such, using a mixed gamma alumina and copper catalyst bed, dimethyl ether and water are reacted to obtain the net result shown in Reaction 11:

[0091] Reaction 11: (CH3)20 + 3H20 -> 2C02+ 6H2 [0092] The energy used to drive the reforming reactions is provided by either combustible or non-combustible sources. In some reactions the energy is provided by combustion of a combustible material and in some embodiments the combustible material is the same as the reforming reaction fuel source.

[0093] An illustrative combustion reaction is shown in Reaction 12 below. The combustion of a source of fuel supplies the energy to drive reactions 1-1 l. An illustrative example is the combustion of methanol with ambient oxygen to release AH of -725.7 kJoules/mole:

[0094] Reaction 12: CH3OH(e) + 3/2 Oz _> COz + 2H20(e) [0095] Thus, theoretically (not being bound by any particular theory), for purposes of this illustration, only 1/5 of the mass of methanol is required to be burned to reform methanol via Reactions 1 and/or 2. This is a small price to pay given that most fuels used in the reforming reaction are cheap, easy to store as a liquid and readily available, even in remote areas of the world.

[0096] Alternatively, in another embodiment, solid hydrocarbons (such as coal), may be burned/combusted to generate the energy required to drive the reforming reactions 1-11, as shown in Reaction 13 (releasing AH = -92 kCal/mole):

[0097] Reaction 13: C + 02 --> COz [0098] In general, the required energy to drive the reforming reactions of the present invention may be furnished by burning small fractions of the reforming reaction fuel source or by using an alternative fuel or other heating methods such as nuclear, solar or electric grid power. In each case, a much larger number of product molecules is produced than is burned or reacted, allowing a much larger amount of fuel to be driven out of the ground than must be used to obtain it. The driver gas consists of mixtures of hydrogen and carbon dioxide, neither of which will react with petroleum, and both of which can serve to reduce its viscosity and provide pressure to drive the petroleum from the ground.

[0099] In yet another embodiment, carbon monoxide derived from various reforming reactions is separated away from the hydrogen gas using a "membrane" or other separation device and further burned to provide additional energy to drive the methanol reforming, as shown in Reaction 14.

[00100] Reaction 14: CO + 1/2 02 -> COz [00101] The burning of CO results in an AH of -283.0 kJoules/mole, again releasing heat for use in driving the reforming reactions illustrated in Reactions 1-1 l.

[00102] With regard to autothermal reforming, a reforming fuel is directly reacted with oxygen in the presence or absence of water. In alternative embodiments, to facilitate combustion of all of the reforming fuel, oxygen gas, air, or alternative oxidizer materials, e.g., hydrogen peroxide, or nitrous oxide, is metered in an amount to react with all of the carbon contained in the reforming fuel. The thermodynamics of the autothermal chemical reactions and the presence of a proper catalyst with proper selection of operating temperature and pressure result in formation of substantially only carbon dioxide and hydrogen gas. However, in use, small amounts of water and other compounds may form by combustion of hydrogen or other byproduct reactions. Where air is used as the oxidizer, there will also be nitrogen left over which can serve as part of the driver gas.

VARIOUS EMBODIMENTS

[00103] According to the present invention, a portable, highly economic COz and H2 generation system is created which enables enhanced oil recovery to be conducted wherever the candidate oilfield may be. The COz generated in the present invention may be injected into an oil well for enhanced oil recovery. The present invention also generates large supplies of hydrogen, which may be used to enhance underground oil recovery in a similar fashion to COz (as described above), or alternatively split off from the COz product to be used for other purposes, including petrochemical hydrogenation or electrical power generation.
Depending upon factors such as the particular composition of the underground oil, as well as the local cost of electrical power, the user of the present invention may find it advantageous to use the hydrogen in different proportions for these various purposes.

[00104] Hydrogen gas may be mixed with the carbon dioxide gas and injected into the oil well. Alternatively, the hydrogen may be separated from the carbon dioxide.
The hydrogen gas may be injected into the oil well, followed by injecting carbon dioxide gas.
Alternatively, the carbon dioxide gas may be injected first, followed by injecting the hydrogen gas.

[00105] In an alternative embodiment, the hydrogen gas may be sold to the petrochemical, or other industry. In the future, it may also be sold as a fuel for hydrogen-electric cars.
Alternatively, the hydrogen may be burned, using for example a gas turbine, to generate electricity. The electricity may be used to provide power for various operations of the oil site.
Alternatively, the electricity may be sold to utility companies by feeding the electricity back into the grid.

[00106] The scale of the present invention is simultaneously portable and also sized to generate sufficient driver gas for economic recovery of oil. For example, consider a near-depleted oil well that presently generates 1 barrel of oil per day.
Established industry guidelines estimate 1 additional barrel of oil recovered for every 5,000 to 10,000 standard cubic feet (5-10 kcf) of COz injected into a near-depleted oil well. Therefore, in order to bring the capacity of the near-depleted oil well up from 1 Ba/day to 100 Ba/day, the present invention should be sized to generate approximately 1,000,000 standard cubic feet (1,000 kcf) of COz per day. That is, in one embodiment of the present invention used for enhanced oil recovery in an oil field producing 100 barrels per day, an embodiment of the present invention should be sized to produce an output of COz gas on the order of one million cubic feet per day (1 MMcf/day).

[00107] However, the present invention is by no means limited to an apparatus that produces COz at a rate of 1 MMcf/day. For example, if an oil well is expected to produce 10 Ba/day, an embodiment of the present invention may be sized to produce an amount of COz equal to approximately 100,000 standard cubic feet (100 kcf) per day. Alternatively, if an oil field is expected to produce 1,000 Ba/day, an embodiment of the present invention may be sized to produce an amount of COz equal to approximately 10 million standard cubic feet (10 MMcf) per day. Since the volume of the reaction chamber, and hence the volume of COz produced, grows as the cube of the linear dimension of the reaction chamber, an apparatus that produces 10 times the amount of COz would have a linear footprint increase of approximately 2.2 times (cube-root of 10). That is, an apparatus sized to produce 10 MMcf/day of COz would only be sized about two times larger in each linear dimension than an apparatus designed to produce 1 MMcf/day of CO2.

[00108] Therefore, based on the above analysis, it is apparent that an apparatus according to the present invention may be produced/manufactured for any appropriate oil well and/or oil field size at only a small incremental increase in production/manufacturing cost.
Therefore, the present invention is a highly economical, highly portable, and highly modular apparatus that may be customized to an oil well and/or oil field of any size. Therefore, the present invention may be sized appropriately, and any mention of particular sizes in this description is illustratively of but a few particular embodiments of the present invention, and is not meant to limit the scope of the present application to any particular size described.

[00109] The present invention may also be configured as a modular system, which may include all or part of the following set of components:

[00110] A method of transportation, such as a truck, boat, or aircraft, upon which the system is mounted or carried, thereby making it portable.

[00111] A fuel reformer, capable of reacting a fuel with water to produce a mixture of COz and hydrogen gas, sized to an output rate appropriate for enhanced oil recovery operations.
Depending upon the availability and cost of local fuel types, the reformer can be designed to operate with various candidate organic material feedstocks, including coal, crude oil, crop or forestry residues or other forms of biomass, alcohols, natural gas, refined petroleum products, oil shale, tars, and urban, industrial, or rural waste products. Examples of the design of such driver gas reformers are discussed above.

[00112] A gas separator, capable of separating the COz from the hydrogen, thereby giving the user of the present invention a choice of how much hydrogen to send underground with the C02, and how much to retain for surface utilization. Candidate separator systems include sorption beds, COz freezers, membranes, and centrifugal separators.

[00113] A high pressure compressor, capable of sending the COz as well as the portion of hydrogen intended for underground use, deep into the well for use in oil extraction. The compressor should be effectively explosion proof. This can be accomplished by using an explosion-proof pump, or alternatively by housing a pump that is not rated explosion-proof within a container that provides an inert environment.

[00114] A set of heat exchangers, designed to maximize the thermal efficiency of the reformer system.

[00115] A power generator, such as a gas turbine, internal combustion engine, or fuel cell system, capable of utilizing the hydrogen product separated by the gas separated to generate electricity.

[00116] A set of controls which can use subsurface data to regulate the operation of the system, thereby allowing it to operate with minimal human supervision or labor. The subsurface data may include total pressure, partial pressure of carbon dioxide, partial pressure of hydrogen, temperature, and/or viscosity of the oil.

[00117] A gas capture system that allows the COz and hydrogen that is released from the oil emerging from the ground to be captured and sent via the compressor back underground for reuse.

[00118] The above components may be mixed and matched by the user of the present invention in appropriate combinations based on local conditions and market prices. For example, if the oil site has a high power requirement, or the local cost of electricity is high, the H2 gas may be separated from the COz using a gas separator as described above, and the H2 may be burned in a gas turbine to generate electricity. The electricity may be either used onsite to provide power for the oil field, or else sold to an electric distribution company by feeding the electricity into the electric grid. Therefore, a portable and modular system is created for enhancing oil recovery wherever a candidate oil field may be.

ECONOMICS OF HYDROGEN GAS PRODUCTION

[00119] As discussed in greater detail throughout the present disclosure, the reforming of fuel is provided for production of driver gas used in the extraction of oil from the ground or from an oil well. In one embodiment, the generated driver gas, e.g., hydrogen-rich gas, is used for recovering materials from currently economically non-viable resources, including extracting oil trapped in depleted wells, liquefying oil shale, and forcing out methane trapped in coal beds.
Currently there are tens of thousands of depleted oil wells all over the world, which collectively possess billions of barrels of petroleum resources that cannot conventionally be extracted by economic means.

[00120] The driver gas of the present invention is injected into the ground, where it softens highly viscous petroleum residues and displaces and mobilizes them for economic recovery.

[00121] These uses compare with the use of helium or other stored compressed gases as driver gas at an oil well recovery site. However, such gases are normally transported at very high pressures (2,200 psi) and in very heavy gas bottles (e.g., K-bottles, weighing approximately 55 kg each with, for example, only 1.1 kg of He). Using easily transported methanol to perform Reaction 1 or 2, or better yet, crude petroleum from the site itself, allows the production of a high-hydrogen-concentration gas without a large electrical requirement needed for electrolytic gas generators. In this sense, gas generation for use in the field provides a significant cost benefit over conventional methods for generating a hydrogen-rich gas.

[00122] Process embodiments of the present invention can take place as a reforming reaction temperature between 200 C and 400 C, depending on the fuel source and catalyst, and more preferably at about 400 C. As such, the reforming feed, i.e., fuel and water sources, are heated to boiling temperature, vaporized, then continued to be heated to the above temperature range, where they react to from driver gas. After the reforming reaction, the gas product can be cooled.
The heat is provided by combustion of a fuel or via a non-combustible source.

[00123] With regard to using a combustible reaction to supply the energy to drive the reforming reaction, a spark plug, incandescent wire, or any other ignition device is typically used to initiate the reaction.

[00124] The following description is provided as an illustrative example and is not meant to limit the description herein.

[00125] Step 1: Preheat Reformer Feed, Cooling of Gas [00126] The reformer feed (fuel and water) enters the system at 20 C. Use of methanol will be provided for illustrative purposes. The average boiling temperature for the CH3OH and H20 is approximately 90 C. Assuming as an example a small system with a driver gas production rate of 100 standard liters per minute, the heat required to preheat the reformer feed from 20 C to 90 C is 202 J/s. The heat lost during this step is 4 J/s. The aim of this heat exchanger is to have the gas exit at about 35 C. Knowing the preheat will require a total of 206 J/s, the inlet temperature of the hydrogen-rich gas needed is calculated to be 130 C. A heat exchanger model shows that a total length of 2.6 m of tube-in-tube exchanger is needed.
Coiled, the resulting height is about 9 cm.

[00127] Step 2: Begin Boiling Reformer Feed, Begin Cooling Gas [00128] The hydrogen-rich gas will be leaving the reaction chamber at about 400 C. As it cools to 130 C, a heat of 613 J/s is produced, 16.5 J/s of which is lost. To vaporize the CH3OH
and H20, 1308 J/s is needed. Therefore, the gas partially boils the reformer feed. The total length of the tube-in-tube required for this process is 2.1 m. When coiled, the resulting height is about 7 cm. The heat exchangers for Steps 1 and 2 are combined into a single unit.

[00129] Step 3: Finish Boiling Reformer Feed, Cool the Combustion Gas [00130] After Step 2, the reforming feed still needs 710 J/s to finish vaporizing, and in this step, 42 J/s is lost. As calculated in Step 5, the combustion gas will leave the reformer at about 648 C. Giving the reforming feed the heat it needs to boil brings the combustion gas temperature down to 127 C. This takes a length of 2.8 m of the tube-in-tube exchanger, which is about 10 cm high when coiled.

[00131] Step 4: Finish Heating Reformer Feed [00132] The reforming feed is already vaporized and will finish heating when it contacts the top plate of a combustion chamber. Heating the reforming feed from 90 C to 400 C requires 518 J/s. This amount of heat brings the temperature of the combustion gas from 1650 C to 1360 C.

[00133] Step 5: Reforming Reaction [00134] To reform CH3OH & H20, 1080 J/s of power may be used in this example.
This section of the heat exchanger also loses 94 J/s to the surroundings.
Accommodating this, the combustion gas temperature drops from 1360 C to 648 C. The design length of this multiple tube section is about 20 cm.

[00135] An equation for determining the heat used or needed for these processes is Q=Y-mCpOT. The calculations lead to obtaining the AH and heat lost across a given section and the section's length. The heat exchange formulas and calculation methods used for the reformer system design are given in Incropera and DeWitt (1996).

[00136] The following example is provided by way of illustration and is not intended as limiting. An oil recovery estimate of a typical embodiment of the present invention is provided herein. Based on the literature, hydrogen is estimated to displace oil from underground reservoirs with a usage of between 400 to 1200 SCF per barrel, depending on the depth of the oil and other like factors. As such, a value of 800 SCF of reformer gas is used in the following calculation for each barrel of oil recovered.

[00137] One barrel of oil is equal to 42 gallons which weighs approximately 126 kg. The 800 SCF is equal to 21,600 standard liters, which is 982 moles of reformer gas.
When the reformer is using a crude petroleum as the reformer fuel, with an average formula of CH2, then the reforming reaction can be represented by Reaction 15:

[00138] Reaction 15: CH2 + 2H20 --> COz + 3H2 [00139] It can also be seen that the produced reformer gas has the same mixture ratio as if it were commercial methanol as the reformer fuel (see Reaction 2). The average molecular weight of the reformer gas in both cases is 12.5 g/mole.

[00140] Accordingly, the 982 moles of reformer gas are equal to 12.275 kg, which produces 126 kg of oil or 0.097 kg reformer gas/kg of oil.

[00141] However, in the case of Reaction 15, only 14/50 (0.28) of the reformer gas owes its mass to the petroleum. In the case of Reaction 2, 32/50 (0.64) of the reformer gas owes its mass to the methanol.

[00142] Therefore, to produce one kg of oil, the reformer needs to use either 0.097 x 0.28 =
0.027 kg of oil or 0.097 x 0.64 = 0.062 kg of methanol. Using the numbers from Reaction 15, only 2.7% of the oil drawn from the well is required in the reformer in order to drive the rest of the oil out of the well. Alternatively, using the numbers from Reaction 2, 62 grams of methanol is required for every kg of oil produced. Methanol currently is selling for about $0.30/kg. With oil costing approximately $63/barrel, oil is worth about $0.50/kg. In this case, an amount of methanol worth 1.86 cents would recover approximately 50 cents worth of oil, which is a methanol sacrifice equal to 3.72% of the value of the oil produced.

[00143] This example shows that using either Reaction 15 or Reaction 2 is economically feasible for the recovery of oil from a depleted oil well. The use of local petroleum appears to be more efficient, but the use of commercial methanol as a reformer feed eliminates the need to eliminate sulfur or other catalyst poisoning contaminants from crude oil prior to catalyst reformation. Importantly, the above example shows that the reformer embodiments of the present invention, used for producing driver gas, are extremely efficient.

ECONOMICS OF CARBON DIOXIDE PRODUCTION

[00144] The preceding discussion focused on the economics of hydrogen gas production.
Importantly, the processes of the present invention also produce significant quantities of COz.
While the yield from COz Enhanced Oil Recovery (EOR) techniques varies depending upon the reservoir in question, it is generally taken in the industry that where conditions are appropriate for the technique, yields of about 1 barrel of oil per 5,000 to 10,000 standard cubic feet (5-10 kcf) of gaseous COz can be expected. (For a conservative estimate, the following discussion will assume 1 barrel of oil per 10 kcf COz.) For this reason, COz EOR is generally viewed as a viable method to use under conditions where COz can be obtained at a cost of $2/kcf or less (i.e. the cost of COz is less than approximately $20/bbl of oil recovered.) Unfortunately, currently COz supplies are only available at such costs if the oil field in question is situated a comparatively short distance from either natural COz reservoirs or large scale artificial COz sources such as coal-fired power plants, ethanol plants, or steel mills. This situation leaves most oil fields that could otherwise be good candidates for COz EOR stranded out of reach of effective economic recovery.

[00145] As recognized by the present inventors, the invention is a modular, highly portable apparatus/system that may be taken to wherever the oil site may be. Therefore, the present invention provides COz at an economic cost at the oil site. As an example demonstrating the potential economic utility of the present invention, consider the case of a coal-fired unit, whose owner-operator decides to use all of the COz product for EOR, while directing all of the hydrogen for another use, for example, power generation. In this example, the owner-operator has decided to utilize a solid hydrocarbon, such as coal, for the reforming reaction as well as the combustion reaction because, i.e., the coal is readily and cheaply available, as is often the case at oil sites.

[00146] The reforming reaction for coal is shown in Reaction 16:

[00147] Reaction 16: C + 2H20 --> COz + 2H2 AH = +40 kcal/mole [00148] This reaction is endothermic, but can be driven by the exothermic burning of coal as shown in Reaction 17:

[00149] Reaction 17: C + 02 -> COz AH = -92 kcal/mole [00150] Accordingly, four units of Reaction 17 can drive nine units of Reaction 16, leaving:

[00151] Reaction 18: 13C + 18H20 + 402 -> 13 COz + 18H2 OH= -8 kcal/mole [00152] So, in the nearly energy-neutral Reaction (18), 156 kg of C produce 13 kmoles (10.6 kcf) of COz and 18 kmoles (14.7 kcf) of hydrogen.

[00153] A typical price for coal is $30/tonne, or $0.03/kg. At this price, the 156 kg of C
would cost about $4.68. But since this is producing 10.6 kcf of C02, the cost in feedstock per kcf of COz produced comes out to $0.44/kcf, well below the approximately $2/kcf industry benchmark for economic C02-EOR.

[00154] However, in addition, the apparatus according to the present invention has also generated 18 kmoles (14.7 kcf) of hydrogen. The hydrogen may be used with the carbon dioxide in enhanced oil recovery as described in greater detail above. Alternatively, the hydrogen gas may be separated, and used separately from the carbon dioxide gas. For example, the hydrogen gas may be burned in a gas turbine, or sold on the open market to the petrochemicals industry for crude oil refinery, or to other parties for other purposes. If hydrogen becomes a more popular clean-burning fuel in the future, the hydrogen may be sold for other purposes, such as to the transportation industry for hydrogen-electric cars. Alternatively, as noted previously, the hydrogen may be mixed with the carbon dioxide, and used in conjunction with the carbon dioxide for enhanced oil recovery.

[00155] The hydrogen gas may be burned in a gas turbine to produce power, in accordance with Reaction 19:

[00156] Reaction 19: H2 + 1/2 02 --> H20 AH = -66 kcal/mole [00157] Reaction 18 produces 18 kmoles of hydrogen, which translates to 1,188,000 kcal 4,989,600 kJ = 1386 kWt-hr of energy. Assuming a thermal-to-electrical conversion efficiency of 33%, this transforms to 462 kWe-hr. At a typical electricity price of $0.10/kWe, this amount of power is worth $46.20.

[00158] Therefore, by using the present invention, an operator transformed $4.68 worth of coal into $46.20 worth of electricity plus an amount of COz worth $21.20 at the standard EOR
acceptable rate of $2/kcf, and which can be used to recover 1.06 barrels of oil, worth $63.60 at a typical expected price of $60/bbl. Taken together, the value of the electricity plus that of the recovered oil amount to $109.80, or about 23.5 times as much as the $4.68 worth of coal consumed in the process.

[00159] It should be noted that this is a worst case scenario for the operation of the present invention, because by being burned for electricity, the 18 kmoles of hydrogen yield a lower monetary return than the 13 moles of COz. If the hydrogen can be used with equal effectiveness as COz as a means of driving oil out of the ground as described above, instead of producing $46.20 worth of electricity, the hydrogen would yield $88.06 worth of oil, for a total return of $151.66, or 32.4 times the value of the coal consumed.

[00160] Of course, the operator of the present invention will have other costs besides coal, including capital equipment, labor, taxes, insurance, etc., but as shown by the analysis below, provided these and other normal business matters are handled effectively, the potential for profit from such a system could be quite large.

[00161] Profit would be enhanced further if some of the COz and/or H2 used to recover oil can be recaptured and recycled after the oil is brought to the surface.
Effective use of such techniques would make many fuels much more expensive than coal highly attractive for utilization in the present invention. Also note that in the above example, power is being produced without the emission of any COz to the Earth's atmosphere. As a result of widespread concern over global warming, proposals are being considered to create taxes on COz emissions, with typical figures mentioned in the range of $50/tonne COz released. This is equivalent to a tax on coal use of $14/tonne, roughly 47% the cost of typical coal. The present invention would allow coal to be burned to produce power without incurring such penalties.

[00162] Considering the figures from the above example, if 156 kg/day of coal produces 10.6 kcf of COz and 14.7 kcf of hydrogen, then 14,716 kg of coal per day will be needed to supply 1 MMcf of COz, as well as 1.39 MMcf of hydrogen (MMcf = million cubic feet).

[00163] Assuming an oil yield of 1 barreU10,000 cf of COz, such an operation could be expected to recover 100 barrels/day, for a cash value at $60/bbl of $6,000.
The hydrogen will yield 43,585 kWe-hr of electricity, for a total sales value at $0.10/kWe-hr of $4,358/day, and an output power level of 1,816 kWe. At $30/tonne, the cost of the coal to feed the apparatus of the present invention will be just $441/day.

[00164] Thus the total gross income generated by the system of the present invention would be $10,358/day, or about $3.8 million per year. Coal costs will be about $160,000 per year.
Assuming a payroll of $400,000/year for a five-man operating crew, plus $200,000 per year to make interest and principal payments on a total plant and equipment valued at $2 million, plus another $240,000 per year to cover other costs, a total overhead budget of $1 million/year is obtained. Therefore, net profit from system operations according to the principles of the present invention would be about $2.8 million/year.

[00165] The above economic analyses show that both hydrogen and carbon dioxide generated by the present invention, taken alone or in combination, may be profitably used to extract oil from underground or underwater sources, such as depleted oil wells. Similar calculations may be used to show that various other fuel sources for the reforming reaction and the combustion reaction may be profitably used to extract oil from depleted oil wells.
Similar calculations may also be used to show that the principles of the present invention may be used to extract natural gas from underground or underwater sources, such as depleted natural gas reservoirs.

[00166] While the methods disclosed herein have been described and shown with reference to particular operations performed in a particular order, it will be understood that these operations may be combined, sub-divided, or re-ordered to form equivalent methods without departing from the teachings of the present invention. Accordingly, unless specifically indicated herein, the order and grouping of the operations is not a limitation of the present invention.

[00167] While the invention has been particularly shown and described with reference to embodiments thereof, it will be understood by those skilled in the art that various other changes in the form and details may be made without departing from the spirit and scope of the invention.

Claims (42)

1. A method for recovering oil from a near-depleted oil well, comprising:
providing a portable fuel reforming apparatus at a site of the oil well;
reforming a fuel source with water within said apparatus to generate driver gas, the driver gas comprising a mixture of hydrogen gas and carbon dioxide gas;
compressing the driver gas to a pressure appropriate for the oil well;
injecting the driver gas into the oil well; and recovering the oil from the near-depleted oil well.

2. The method of claim 1, wherein the reforming operation further comprises:
combusting a combustible material with oxygen to release energy; and heating the fuel source and water with the energy released from the combustion of the combustible material to a temperature above the reforming reaction point, wherein the fuel source is reacted with water to generate the driver gas.

3. The method of claim 2, further comprising:
mixing an amount of water with the fuel source prior to the addition of energy from the combustion of the combustible material.

4. The method of claim 2, further comprising:
cooling the driver gas, wherein the heat released from the cooling of the driver gas is used to heat the fuel source and/or water to a temperature above the fuel source and/or water's vaporization point.

5. The method of claim 2, wherein the reforming reaction fuel source and combustible material are the same.

6. The method of claim 2, wherein the reforming reaction fuel source and/or combustible material are an alcohol.

7. The method of claim 2, wherein the reforming reaction fuel source and/or combustible material are a crude petroleum product.

8. The method of claim 2, wherein the reforming reaction fuel source and/or combustible material are a refined petroleum product.

9. The method of claim 2, wherein the reforming reaction fuel source and/or combustible material are coal or a derivative of coal.

10. The method of claim 2, further comprising:
contacting a catalyst to the fuel source, wherein the catalyst reduces the temperature and amount of energy required to heat the fuel source and water to a temperature above which the reforming reaction will proceed.

11. The method of claim 2, further comprising:
cooling the driver gas to a temperature below the fuel source's boiling point.

12. A portable apparatus for recovering oil from a near-depleted oil well, comprising:
a first reaction chamber for combusting a combustible material with oxygen to release energy;
a second reaction chamber for reforming a fuel source with water to generate driver gas, a portion of the second chamber positioned within a portion of the first chamber, the second chamber having an outlet and fluidly isolated from the first chamber; and an injection line, operatively connected to the outlet of the second chamber, for injecting the driver gas into the oil well, wherein the energy released in the first chamber heats the fuel source and water in the second chamber to a temperature above the fuel source's vaporization point, thereby reforming fuel source and water into driver gas exiting the portable apparatus via the injection line into the oil well, and wherein the portable apparatus is sized to generate an amount of driver gas appropriate for the near-depleted oil well.

13. The apparatus of claim 12, further comprising:
a first feed leading into an inlet on the first reaction chamber for receiving the combustible material from a first storage container;
a second feed leading into an inlet on the second reaction chamber for receiving the fuel source from a second storage container; and a third feed leading into the inlet on the second reaction chamber for receiving water from a third storage container.

14. The apparatus of claim 13, wherein the second storage container includes a mixture of water with the fuel source.

15. The apparatus of claim 13, further comprising:
a first heat exchanger coupled with an outlet of the first reaction chamber and thermodynamically coupled with the inlet or interior of the second chamber, the first heat exchanger for heating the fuel source.

16. The apparatus of claim 13, further comprising:
a second heat exchanger coupled with the outlet of the second reaction chamber and thermodynamically coupled with the inlet of the second reaction chamber, the second heat exchanger for pre-heating the fuel source and for cooling the driver gas.

17. The apparatus of claim 13, wherein a heat exchanger is positioned within the second reaction chamber, and gases entering this heat exchanger from the first reaction chamber are used to heat the second reaction chamber to the temperature required for the reforming reaction to proceed.

18. The apparatus of claim 12, wherein the first reaction chamber includes an igniter for igniting the combustible material.

19. The apparatus of claim 12, wherein the second reaction chamber is adapted to receive a catalyst to reduce the amount of energy required to heat the fuel source and water to a temperature above which the reforming reaction will proceed.

20. The apparatus of claim 12, wherein the combustible material and reforming fuel source are the same.

21. The apparatus of claim 12, wherein the combustible material and/or reforming fuel source are an alcohol.

22. The apparatus of claim 12, wherein the combustible material and/or reforming fuel source are a crude petroleum product.

23. The apparatus of claim 12, wherein the combustible material and/or reforming fuel source are a refined petroleum product.

24. The apparatus of claim 12, wherein the combustible material and/or reforming fuel source are coal or a derivative of coal.

25. The apparatus of claim 12, wherein the driver gas comprises hydrogen gas.

26. The apparatus of claim 12, wherein the driver gas comprises carbon dioxide gas.

27. The apparatus of claim 12, wherein the driver gas comprises carbon dioxide gas and hydrogen gas.

28. The apparatus of claim 12, sized to produce driver gas at a rate of approximately 100 thousand standard cubic feet per day to 10 million standard cubic feet per day.

29. A portable apparatus for recovering oil from a near-depleted oil well, comprising:
a reaction chamber for reacting a reformer fuel, an oxidizing agent, and water, the reaction chamber having at least one inlet for receiving the reformer fuel, oxidizing agent, and water and at least one outlet for release of the produced driver gas; and an injection line, operatively connected to the outlet of the reaction chamber, for injecting the driver gas into the oil well, wherein the reaction chamber reacts the reformer fuel and the water, thereby generating driver gas exiting the portable apparatus via the injection line into the oil well, and wherein the portable apparatus is sized to generate an amount of driver gas appropriate for the near-depleted oil well.

30. The apparatus of claim 29, wherein the reformer fuel is coal or a derivative of coal.

31. The apparatus of claim 29, further comprising:
a heating element for heating the reaction chamber to a predetermined temperature required to perform an autothermal reforming reaction between the reformer fuel, oxidizing agent, and water.

32. The apparatus of claim 29, further comprising:
a counter-flow heat exchanger to transfer heat from the released driver gas to the incoming reformer fuel.

33. The apparatus of claim 29, further comprising:
a catalyst bed integrated within the reaction chamber to facilitate the autothermal reforming reaction between the reformer fuel, oxidizing agent, and water.

34. The apparatus of claim 29, wherein the driver gas comprises hydrogen gas.

35. The apparatus of claim 29, wherein the driver gas comprises carbon dioxide gas.

36 36. The apparatus of claim 29, wherein the driver gas comprises carbon dioxide gas and hydrogen gas.

37. The apparatus of claim 29, sized to produce driver gas at a rate of approximately 100 thousand standard cubic feet per day to 10 million standard cubic feet per day.

38. A method for recovering natural gas from a near-depleted natural gas reservoir, comprising:
providing a portable fuel reforming apparatus at a site of the natural gas reservoir;
reforming a fuel source with water within said apparatus to generate driver gas, the driver gas comprising a mixture of hydrogen gas and carbon dioxide gas;
compressing the driver gas to a pressure appropriate for the natural gas reservoir;
injecting the driver gas into the natural gas reservoir; and recovering the natural gas from the near-depleted natural gas reservoir.

39. The method of claim 38, wherein the reforming operation further comprises:

combusting a combustible material with oxygen to release energy; and heating the fuel source and water with the energy released from the combustion of the combustible material to a temperature above the reforming reaction point, thereby the fuel source is reacted with water to generate the driver gas.

40. The method of claim 39, further comprising:
utilizing a portion of the natural gas recovered from the natural gas reservoir as the fuel source and/or as the combustible material.

41. A portable apparatus for recovering natural gas from a near-depleted natural gas reservoir, comprising:
a reaction chamber for reacting a reformer fuel, an oxidizing agent, and water, the reaction chamber having at least one inlet for receiving the reformer fuel, oxidizing agent, and water and at least one outlet for release of the produced driver gas; and an injection line, operatively connected to the outlet of the reaction chamber, for injecting the driver gas into the oil well, wherein the reaction chamber reacts the reformer fuel with the water, thereby generating driver gas exiting the portable apparatus via the injection line into the natural gas reservoir, and wherein the portable apparatus is sized to generate an amount of driver gas appropriate for the near-depleted natural gas reservoir.

42. The apparatus of claim 41, wherein a portion of the natural gas recovered from the natural gas reservoir is used as the reformer fuel.