A pulsating FLUE gases generation apparatus with a discharge valve affixed to its cylinder head

Abstract

An internal combustion apparatus for the extraction of highly viscous crude oils, produces pulsating flue gases at a user established temperature, pressure, volume flow rate and pulsating frequency. The operation logic of the apparatus presents three stages: suction, discharge and exhaust. During the suction stage, the cylinder combustion chamber is substantially filled with a pressurized combustible gases mixture, which after ignition produce large volume of expanding combustion gases at high pressure, which escape through a discharge valve affixed to the cylinder head during the discharge stage. The exhaust stage allows for the remaining combustion to be evacuated. The combustion gases mixed with air and / or other gases produce flue gases at the volume rate required to pressurize the wellbore´s surrounding formation at a specified temperature to lower the oil viscosity. The pulsating effect and the Carbon Dioxide content in the flue gases improves the mobility of the oil to the wellbore.

Description

[0001] A PULSATING FLUE GASES GENERATION APPARATUS WITH A DISCHARGE VALVE AFFIXED TO ITS CYLINDER HEAD

[0002] BACKGROUND OF THE INVENTION

[0003] 1 . Field of the Invention

[0004] The present invention relates to the combustion of combustible gases and apparatus with a discharge valve affixed to the cylinder head for the generation of pulsating hot flue gases to be injected into oil wells in order to lower the viscosity of the Heavy and Extra-Heavy oils and simultaneously and increase the pressure of the formation surrounding the wellbore.

[0005] 2. Description of Related Art

[0006] When the conditions of a reservoir, whether due to the high viscosity of the crude oil or insufficient prevailing formation pressure, do not allow for the oil to be produced efficiently, then Enhanced Oil Recovery (EOR) processes should be implemented in order to facilitate the flow of crude oil from the formation to the wellbore.

[0007] In Enhanced Oil Recovery (EOR), favorable conditions are sought for the flow of fluids in the reservoir, usually, through the addition of heat, chemical interaction between the injected fluid and the crude oil, mass transfer, and change in the properties of said crude oil, so that its mobilization through the formation is facilitated.

[0008] There are several Enhanced Oil Recovery (EOR) techniques and methods available. The implementation of one process over another depends mainly on technical and economic factors. Likewise, it is necessary to establish the production strategy, which could be activating: (i) specific wells, to then produce oil through the surrounding wells; or rather, (ii) a specific well, to then produce oil through the same well.

[0009] One of the methods that can be implemented regardless of the production strategy consists of injecting hot flue gases into the well until a predetermined pressure and temperature in the formation is reached, which allows increasing the production of (i) very high viscosity crude that presents little mobility in said formation, or (ii) oils of any viscosity in formations that present low pressure.

[0010] The production of highly viscous crude oil has posed a great challenge to engineers, particularly when it is required to lift the oil from the formation to the surface. Throughout the years, many potential solutions were implemented with varying success.

[0011] The basic idea is to lower the oil viscosity by any means, but the most efficient way to accomplish this is basically through an increase in temperature. It is well known that the oil viscosity drops several orders of magnitude when the temperature is raised. Once a particular oil reaches its asymptotic lowest viscosity level, it will remain the same even for higher temperatures.

[0012] Other ways to lower the viscosity were to inject different gases or gas mixtures into the wells, with the expectation that they would combine with the oil in the formation by its miscibility and / or solubility characteristics.

[0013] Based on the fact that temperature is the most significant factor in lowering the oil viscosity, most of the processes that appear in the literature and patents are focused on this specific property. Amongst them, the injection of hot gases into the wells has caught much interest. Different hot gases were injected with varying results both from the recovery efficiency and the economic points of view. A well-known technique consists in injecting steam into the well, but the drawback is basically that said steam will condensate forming water, and now it becomes necessary to lift for a while oil with a significant water content. Other popular techniques, considered compressing all sorts of gasses and then injecting them into the wells. Some of the gases used included but were not limited to natural gas from the same reservoir, Carbon Dioxide (CO2), Nitrogen (N2), Oxygen (O2), and other gas mixtures. The important factors affecting their implementation were mostly economical.

[0014] What is known is that Nitrogen (N2) has very low solubility with the oil, so it definitely would transfer heat into the formation and act as a driving force to push said oil from the reservoir to the wellbore. Steam has proven to work in other oil recovery techniques, so if the gas contains a certain amount of water vapor or steam, then it will help heat the oil to lower its viscosity even more. Finally, it is known that Carbon Dioxide (CO2) will dissolve into the oil and effectively transfer heat into the formation further lowering the oil viscosity. A gas mixture that contains all three of these constituents are hot flue gases.

[0015] Hot flue gases offer several advantages over other processes since it is not too complicated to generate, is quite economical, the equipment is simple to use and can be easily mobilized from one location to another, and can be individually tailored for a specific well or cluster of wells.

[0016] In the beginning, the process of generation of hot flue gases for injection in oil wells was considered a simple task. Initially, the exhaust fumes of several diesel trucks were compressed and injected into the wells. Soon the users discovered that this process would typically send fumes that were not completely combusted sometimes with sulfur traces producing high corrosion in the metallic components of the wells (particularly production tubing and casing). Furthermore, non-desirable gases such as Carbon Monoxide (CO) and Nitrogen Oxides (NOx) were also generated, as well as soot and ashes which would plug the formation affecting the mobility of oil from the formation to the wellbore.

[0017] Next, it was thought to mobilize combustion gases from various sources to compression stations and then inject said gases into selected wells; however, this procedure carries significant costs. A more practical concept is to have small hot flue gases generating units that can be moved from well to well and inject the produced gases into those wells individually. This method allows combustion gases to be injected at user-set temperatures until reaching previously established formation pressures.

[0018] Other hot flue gases generation processes were introduced, that produced a continuous flow of combustion gases. A couple of versions were presented in Patents US 6,796,789 and US 5,340,020 where flameless combustion was produced, the former worked without a catalyst, while the latter required a catalyst. Other concepts were Patents US 5,839,270 where the combustion chamber is configured to work with a sliding blade rotary heat- engine. Another concept that produces flameless combustion appears in publication US 201028493A1 where a precombustion chamber adapted to heat and at least combusts a primary fuel. The primary characteristic of these inventions is that all of them produce a continuous flow of flameless combustion gases.

[0019] Some problems of the prior art were that in order to be implemented for applications in the oil industry, it typically required: (i) a posterior cooling means (such as but not limited to a cooling tower type heat exchanger), and (ii) a compressor to increase the pressure of the gases to a user-established level.

[0020] SUMMARY OF THE INVENTION

[0021] A novel pulsating flue gases generator that uses readily available natural gas (or any other combustible gas) mixed with air as a combustible mixture, the subject of this invention patent, was developed providing the user complete control in the production of hot flue gases for injection into oil wells. The combustion gases are produced by the ignition of the stoichiometric mixture of natural gas with an excess of Oxygen (O2) which assures complete combustion. In turn, the hot flue gases are produced by mixing the generated combustion gases with fresh cooling air. The pulsating effect is produced by a piston moved by any reciprocating means (such as a crank shaft), which completely differs from a continuous means (such as a turbine). The combustion gases produced by the ignition of the combustible gases mixture acting on the piston of the reciprocating means, forces the pressure of the system to build up in every stroke until a pre- established wellbore pressure is reached, while the flue gases temperature can easily be controlled with fresh compressed air (or any other heat exchanger means) until said flue gases temperature is cooled to the required operating temperature and the volume rate of combustion gases is controlled by the set volume of the cylinder (or cylinders) and the number of strokes per unit of time. Other potential advantages would be due to the pulsating pressure effect on the formation, where it could be anticipated for the flue gas to penetrate faster into the formation and to take advantage of the slight agitation to help in the mobilization of the oil from said formation to the wellbore.

[0022] The concepts related to the operation of any internal combustion engine are very well known. It is clear that depending on the cycle used or whether the combustion occurs due to a spark (or ignitor) or very high compression that generates the necessary heat, the process basically requires a suction stage where a combustible gas mixture enters the cylinder which is first compressed, then combustion takes place, and finally an exhaust stage where the combustion gases are evacuated from the cylinder. In order for this process to take place, a piston must reciprocally move within a cylinder. Said piston is attached to a link that transmits the reciprocating motion to produce rotation of a crankshaft (as a simple slider crank mechanism). All the known internal combustion processes consider the compression of the combustible mixture in a set ratio established by the combustion chamber volume within the cylinder before the combustion takes place, and once combustion occurs, the expansion of the gases increases the pressure within the cylinder exerting force on the piston which in turn produces torque to turn the crankshaft. This positive displacement process produces a pulsating effect on the exhaust combustion gases during the exhaust stage as they are evacuated after the combustion stage within the cylinder took place. Any internal combustion engine that produces much torque with minimal consumption of combustible gas mixture, is considered very efficient.

[0023] By taking some of the basic concepts of any internal combustion engine, but instead of producing a torque to turn a crankshaft, it is the crankshaft (or any other means) that reciprocally moves a piston within a cylinder; evidently, the purpose of said engine radically changes. In this case, what is sought in this somewhat backward operation of the referred internal combustion engine, is the generation of the largest amount of combustion gases with the least amount of combustible gas mixture.

[0024] The main objective of this invention is to generate large amounts of hot flue gases, produced by the stoichiometric combustion of natural gas, or any other combustible gas, mixed with air with an excess of oxygen (O2) in order to assure that complete combustion takes place, for the purpose of injecting said hot flue gases into oil wells so as to lower the viscosity of highly viscous oil and to pressurize the formation surrounding the wellbore.

[0025] Another important objective of this invention is to produce a pulsating effect of the hot flue gases being injected into any oil well in order to improve the penetration of the gases into the formation surrounding an oil well and provide some agitation that should improve the mobility of the oil from said formation to the wellbore.

[0026] Still, another objective of this invention is to provide a pulsating positive displacement to the hot flue gases being injected into any oil well, in order to accumulate the wellbore pressure in each stroke of the reciprocating means until a user-established maximum pressure within said wellbore is attained.

[0027] Yet, another objective of this invention is to inject into the oil well, as part of the hot flue gases, (i) Carbon Dioxide (CO2) which is highly soluble with the crude oil, thus aiding in lowering even more the viscosity and facilitating the production through the production tubing as said gas expands when it goes from the bottom of the well to the wellhead, and (ii) Nitrogen (N2) which has a very low solubility with said oil, but aids in heating up the oil and providing a piston effect to push the oil from the formation to the wellbore.

[0028] A further objective of this invention is to be able to cool the hot flue gases being injected into any oil well to a user-established maximum temperature, depending on the oil well’s completion characteristics and / or the type of production tubing available.

[0029] Finally, a very important objective of this invention is to provide a user-established volume rate of hot flue gases to be injected into any oilwell per day, depending on the ellipsoid volume surrounding the wellbore to be stimulated.

[0030] Other lesser important objectives are to (i) easily reposition the equipment from one location to another, (ii) reduce or completely eliminate the implementation of an external cooling tower (or any other type of heat exchanger) between the hot flue gas generator and the wellhead, and finally, (iii) be able to control the stoichiometric mixture of the combustible gas and air mixture by means of a gas emission sensor (or a chromatograph) located, when needed, right before the wellhead.

[0031] The flue gases generation apparatus object of this invention is constituted by a combustion component set and a cooling component set. The combustion component set is embodied by one or several cylinders with their corresponding piston, and at least for each cylinder: (i) one sparkplug, (ii) one intake valve, (iii) one exhaust valve, and what is completely novel, (iv) at least one discharge valve. Contrary to other internal combustion engines, the purpose of this engine is to generate as much combustion gases as possible, completely disregarding the torque on a crankshaft. As a matter of fact, in this concept as explained before, it is the piston that is moved by a crankshaft or any other reciprocating means.

[0032] In this invention, a preferred embodiment of the combustible component set is described where the discharge valve is affixed to its cylinder head.

[0033] The operation logic of the hot flue gases generator according to this invention, is completely different from any common internal combustion engine. Here, three definite stages exist: (i) a suction stage, (ii) a discharge stage and (iii) an exhaust stage. In this invention, during the suction stage the intake valve is open and as the piston travels to its farthest position from the cylinder head, its combustion chamber is substantially filled with a pre-compressed stoichiometric mixture of the combustible gas and air, with an excess of Oxygen (O2) in order to assure complete combustion, at a pressure equivalent to what would have been the compression pressure for the ignition to occur (depending on the compression ratio for the particular cylinder volume). Once the piston is nearing its farthest position from the cylinder head the intake valve closes; while the discharge and exhaust valves remain closed, the pressurized combustible mixture is ignited by means of a spark, causing the combustion gases to expand violently opening only the discharge valve (or valves), where the expansion gases at very high pressures are forced to rush out from the combustion chamber and flow into the cooling component set through an exit check valve located between said discharge valve and the mixing chamber of said cooling component set; all of this occurs while the piston is now moving towards the piston’s nearest position to the cylinder head, further aiding the discharge process of the just generated combustion gases. Once the pressure at both sides of the discharge valve becomes the same, said discharge valve will close. Right before this occurs, the exit check valve closes holding back the accumulated pressure between the flue gas generator and the well's wellhead. As soon as the discharge valve closes, the exhaust valve at the cylinder head will open thus evacuating the remaining combustion gases and further liberating the pressure within the cylinder combustion chamber between the piston and the cylinder head, which allows the piston to move freely without any significant counterpressure. Once this process is completed, a new cycle will begin.

[0034] Any preferred embodiment, must take into account that: (i) the discharge valve must be preloaded, by any means known or available to those skilled in the art, in order to avoid its opening while the combustion chamber is being filled with the pre-compressed combustible gas mixture, and (ii) the motion of the piston may be provided by any means that can produce a reciprocating motion.

[0035] When the reciprocating motion of the pistons is provided by the crankshaft of an internal combustion engine with several cylinders, then at least one of the cylinders of the internal combustion engine is used as a power cylinder to impress a rotational motion onto said crankshaft, and at least another one of the cylinders of the internal combustion engine may be used for the generation of combustion gases. Then the handling of the exhaust gases of the cylinders implemented for the generation of combustion gases and the exhaust gases produced by the power cylinders of the reciprocating motion actuator, establish two preferred embodiments for the pulsating flue gas generator; where (i) in the first preferred embodiment, said exhaust gases are discarded into the atmosphere, while in the second preferred embodiment (ii) said exhaust gases (only if the reciprocating motion is provided by an internal combustion engine where the combustible gas mixture for the power cylinders is exactly the same as the combustible gas mixture used for the generation of the hot flue gases) could be cooled and mixed together with the ambient air at the intake end of the fresh air compressor, before being compressed and injected into the mixing chamber of the cooling component set, becoming an additional source of combustion gases with a certain percentage of Carbon Dioxide (CO2). Evidently, this last preferred embodiment, allows taking advantage of all combustion gases generated; however, the main disadvantage is that an additional mixing chamber plus a heat exchanger means are required. An economic analysis should be performed for each particular application, in order to determine which preferred embodiment is to be implemented. Furthermore, optionally, particularly in areas where the ambient temperature is very low or freezing, the second preferred embodiment could take advantage of some or all the hot air that comes out of the engine's fan cooled radiator (part of its own cooling system) which could also be diverted towards the intake end of the fresh air compressor, thus taking advantage of this additional heat source that will increase the air to combustion gases ratio when cooling to the user-specified temperature before entering the well's wellbore.

[0036] Since in this setup, the piston reciprocates within its cylinder, the combustion gases produced will provide a pulsating effect. The frequency of the pulsating effect will depend on the number of strokes per unit of time and the number of cylinders. It is important to clarify, that due to the fact that the number of strokes per unit of time is very low, it is quite impossible to reach a resonant condition in the production tubing, so no damage or fatigue could be expected to occur downhole or with the surface facilities. The pulsating effect downhole should rather aid in the mobility of the flue gases within the oil well formation. A slight agitation could also be expected to occur which would likewise facilitate the flow of the oil from the formation into the well's wellbore.

[0037] It should be understood that the pressure between the exit checkvalve (located right after the discharge valve) and the well's wellbore, will increase slightly with each combustion cycle and it will accumulate over a specific time period. Once the accumulated pressure reaches the pre-established pressure value, it should be maintained at that level until the hot flue gases volume has been attained. At this moment, the system would shut off, ending the hot flue gases injection process. Of course, should any additional pressure be required, an external compressor could also be implemented.

[0038] Since the temperature of the combustion gases exiting the combustion chamber of each cylinder is higher than the user-established maximum flue gas injection temperature (which depends on the well completion characteristics), the simplest way to control said temperature is: (i) for the first preferred embodiment, by mixing these combustion gases with compressed fresh air injected into the mixing chamber of the cooling component set until the user established temperature is reached, while (ii) for the second preferred embodiment, by mixing and cooling the exhaust gases of the cylinders implemented for the generation of combustion gases, the exhaust gases produced by the power cylinders of the reciprocating motion actuator and optionally, the hot air that comes out of the engine's fan cooled radiator, before being compressed and mixed together with the combustion gases within the mixing chamber of the cooling component set. It should be noted that for both preferred embodiments, only if necessary, further cooling might also be provided by a cooling tower or any other type of heat exchanger.

[0039] The volume of the combustion chamber within each gas generator cylinder, the number of such cylinders used for hot flue gas generation and the number of strokes per unit of time, establish the volume rate of hot flue gases that are injected into the well every 24 hours. This volume rate is also adjustable since the number of strokes per unit of time can be easily controlled.

[0040] Regarding the flue gas generator apparatus, the whole equipment setup is expected to be skid mounted which can easily be transported with a truck from one location to another. The clean (all Sulphur traces and contaminants removed) combustible gases could be provided from any source by any means.

[0041] Since the combustion of the stoichiometric mixture of combustible gases and air presents an excess of Oxygen (O2), the combustion is expected to be complete, this means that the hot flue gases will be constituted specifically by Carbon Dioxide (CO2), Nitrogen (N2), steam (H2O) and part of the Oxygen (O2); however, just to assure the quality of the combustion gases, an emissions sensor (or a gas chromatograph) can be placed between the flue gas generator and the well's wellhead to provide the required data to correct the mixture of hot combustible gases and air entering the system in order to assure that the levels of undesirable gas emissions, such as Carbon Monoxide (CO) and / or Nitrogen Oxides (NOx), are below the maximum levels established by the Environmental Protection Agency (EPA) before entering the well.

[0042] The flue gases generator in both preferred assembly embodiments will work according to the operation logic described above, producing hot flue gases which together with the highly soluble Carbon Dioxide (CO2) will lower the viscosity of the crude oil within the well's wellbore and increase the formation pressure surrounding the well pushing the oil towards said well's wellbore. Furthermore, it is expected that the pulsating effect will promote a faster penetration of the flue gases into the formation and the slight agitation, that is likely to be produced, should facilitate the flow of oil towards the referred well's wellbore.

[0043] Each flue gas generator cylinder head, must have at least: (i) a intake valve; however, the number of valves and flow openings through said intake valves, is established by the amount of gas mixture that must enter the combustion chamber of each cylinder during the suction stage, (ii) a discharge valve; however here also, the number of valves and flow openings through said at least one discharge valve, is established by the amount of expanding gases produced within the combustion chamber as soon as the gas mixture is ignited by the spark produced by a sparkplug when combustion takes place, (iii) an exhaust valve; however here likewise, the number of valves and flow openings through said exhaust valves, is established by the amount of combustion gases that remain within the combustion chamber once the produced high-pressure combustion gases have been discharged through the at least one discharge valve, and (iv) a sparkplug; though, redundant sparkplugs may also be installed in order to assure the spark produced by said at least one sparkplug is sufficient to ignite the stoichiometric gas and excess O2 mixture within the substantially filled combustion chamber.

[0044] The combustion chamber volume for each combustion gases generator cylinder is established by the cylinder's bore diameter and stroke length.

[0045] The minimum number of combustion gases generator cylinders required by the flue gases generator may be established by the calculated volume flow rate of flue gases to be injected into the formation surrounding the wellbore that is necessary to increase said formation’s pressure and temperature, divided by the number of strokes per unit of time (could be RPM in an internal combustion engine) and the combustion chamber volume of a single combustion gases generator cylinder. The intake pressure and volume flow rate of flue gases to be injected into a specific well may establish the minimum number of strokes per unit of time required for each combustion gases generator cylinder.

[0046] The number of pulses that the pulsating flue gases generator produces, depends on the summation of the number of strokes produced per unit of time by each combustion gases generator cylinder. The number of strokes per unit of time may be user controlled.

[0047] The temperature of the flue gases to be injected into the oil well's wellbore depends on the pulsating combustion gases produced inside the combustion chamber of each combustion gases generator cylinder to be mixed within the mixing chamber of the cooling component set together with: (i) the amount of compressed fresh ambient air, for the first preferred embodiment, or (ii) the amount of compressed fresh ambient air that requires to be mixed and cooled with the exhaust gases and optionally with the hot air coming from the engine's own cooling system, for the second preferred embodiment.

[0048] A temperature sensor located between the pulsating flue gases generator and the well’s wellhead may control the amount of fresh ambient air to be mixed with the combustion gases. The flue gases injection temperature may be user controlled.

[0049] The pressure of the flue gases to be injected into the well’s wellbore depends on the sudden pressure increase produced by the combustion of the combustible gases mixture within each combustion chamber.

[0050] In both preferred embodiments, the pressure of the flue gases injected into the wellbore is accumulative with each combustion pulse.

[0051] Between the pulsating flue gases generator and the well’s wellhead there may be a pressure sensor that once the pre-established pressure is reached, it will maintain this pressure until the flue gases volume is attained. The pre-established pressure may be user controlled.

[0052] The user may have absolute control over all the parameters required to increase the formation pressure and lower the crude oil’s viscosity. Between the flue gas generator and the well’s wellhead, there may be a gas emission sensor (or a chromatograph) that measures the concentration of the emissions of the generated flue gases that enter the wellbore.

[0053] The stoichiometric combustible gas and air mixture that enters the combustion chamber of each combustion gases generator cylinder through the at least one intake valve, depends on the combustible gas used.

[0054] The gas emission sensor (or a chromatograph) measurements allows control on the intake temperature and amount of air required to attain the proper stoichiometric combustible gas and air mixture that enters the combustion chamber of each combustion gases generator cylinder in order to assure that the combustion is complete and the level of emissions that could cause corrosion of the wellbore metallic components and / or become a health hazard are lower than the maximum levels established by the EPA.

[0055] Optionally, the duct that connects the exit check valve to the cooling component set may include an inlet that could be used if there would be a need to introduce additional gases (such as CO2) or any other substances for added solubility in the crude oil to further reduce its viscosity or facilitate its mobility, even to inhibit corrosion of the metallic components of the completion.

[0056] The number of revolutions per minute (RPM) of the internal combustion engine may depend on the intake gas mixture and temperature, as well as the mass flow rate of combustible gases that is required at the formation surrounding the well’s wellbore.

[0057] If convenient, water vapor may also be injected as a mist into the mixing chamber of the cooling component set so that steam is included within the flue gas mixture depending on the user-established mass flow rate required at the formation surrounding the wellbore.

[0058] Other objects, advantages, and features of the present invention will become apparent from the following detailed description of the invention when read in conjunction with the accompanying drawings and claims.

[0059] BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 , is a general schematic representation of the complete pulsating hot flue gases generation apparatus in the first preferred embodiment of the combustion component set where the discharge valve is attached to its cylinder head and the cooling component set mixes and lowers the temperature of the combustion gases with compressed fresh ambient air.

[0060] Figure 2, is a general schematic representation of the complete pulsating hot flue gases generation apparatus in the second preferred embodiment of the combustion component set where the discharge valve is attached to its cylinder head and the cooling component set mixes and lowers the temperature of the combustion gases with a pre-cooled and recompressed mixture of exhaust gases and other heat sources together with fresh ambient air.

[0061] Figure 3, is a detailed schematic representation of the preferred embodiment of the combustion component set where the discharge valve is affixed to its cylinder head.

[0062] Figure 4, shows the different stages of operation of the preferred embodiment of the combustion component set for both first and second preferred embodiments of the pulsating hot flue gas generation apparatus where the discharge valve is attached to its cylinder head.

[0063] DETAILED DESCRIPTION OF THE INVENTION

[0064] The explanations that appear in this detailed description are valid for any pulsating hot flue gas generator, where the discharge valve is affixed to the cylinder head of a combustion component set actuated by any reciprocating means.

[0065] Figure 1 , presents a schematic representation of the first preferred embodiment of the complete pulsating hot flue gas generation apparatus 10; while in Figure 2, a schematic representation of the second preferred embodiment of the complete pulsating hot flue gas generation apparatus 1 1 is presented. In both figures, at the preferred embodiment of the combustion component set 15, the discharge valve 36 is affixed to the cylinder head 24. The ignition of the combustible gas mixture 89 within cylinder 16 produces the gas generator combustion gases 90 which flow through discharge valve 36 and exit check valve 46 as discharge combustion gases 91 into the mixing chamber 61 of the cooling component set 60 of both pulsating hot flue gas generation apparatus 10 and 1 1 . In both cases, a possible embodiment of a cooling component set is shown; however, since its sole purpose is to mix and cool gases to the user established temperature, in principle, any other heat exchanger design or configuration (even any commercially available units) could be used.

[0066] At this point, it is beneficial to explain in general terms the basic differences between a conventional internal combustion engine and the pulsating hot flue gas generation apparatus 10 and 11. Any internal combustion engine and both pulsating hot flue gas generation apparatus 10 and 1 1 (Figures 1 and 2) present a sparkplug 54 that ignites with spark 55 a combustible gases mixture 89 that enters the combustion chamber 19 (Figure 3) through an intake valve 30. In the conventional engine, the combustible gases mixture enters at very low pressure (atmospheric or close to atmospheric pressure) the combustion chamber of a cylinder during the suction stage, then the combustible gasses mixture is compressed according to an established compression ratio, before the ignition with spark 55 takes place; however, in both pulsating hot flue gas generation apparatus 10 and 1 1 , the combustible gases mixture 89 that enters the combustion chamber 19 through the intake valve 30, is instead at a much higher pressure attained by precompressing said combustible gases mixture 89, and substantially fills the entire combustion chamber 19 of cylinder 16 before the ignition with spark 55 takes place. Additionally, in a conventional engine, due to ignition with spark, a sudden increase of pressure and an increment in the volume of combustion gases pushes a piston generating a torque through a link that provides rotation to a crankshaft; while, in both pulsating hot flue gas generation apparatus 10 and 1 1 the sudden increase of pressure and expanding combustion gases 90 does not push piston 21 , but instead forcibly opens a discharge valve 36 which allows said expanding gases to flow towards the cooling component set 60 and lowering the pressure and temperature of these combustion gases 90. This discharge valve 36 does not exist in a conventional internal combustion engine. Regarding the exhaust stage, the internal combustion engine and both pulsating hot flue gas generation apparatus 10 and 1 1 present exhaust valves 48 that work exactly the same way, when evacuating the remaining combustion gases 90 from the combustion chamber 19 of cylinder 16 to the atmosphere.

[0067] Furthermore, it is important to point out that the piston 21 of both pulsating hot flue gas generation apparatus 10 and 1 1 may be reciprocally actuated by any means; however, when the piston 21 is actuated specifically by an internal combustion engine, then the cylinders of the internal combustion engine that provide the reciprocating motion to the combustion gases generating cylinders 16 through a crankshaft are referred to hereon in as power cylinders.

[0068] The preferred embodiment of the combustion component set 15 for both preferred embodiments of the pulsating hot flue gas generation apparatus 10 and 1 1 is basically comprised of cylinder 16, piston 21 , and cylinder head 24, where said cylinder head 24, in turn, has a sparkplug 54 and a set of valves affixed to it, composed of an intake valve 30, an exhaust valve 48 and a discharge valve 36.

[0069] The intake valve 30, the exhaust valve 48 and the discharge valve 36 affixed to cylinder head 24, present valve stems 31 , 49 and 37 respectively, whose outer cylindrical surfaces make sliding contact with the inner cylindrical surface of valve stem guides 12, 13 and 14 respectively provided in the cylinder head 24.

[0070] The combustible gas 87 is pressurized by the intake gas compressor 57 to produce compressed intake combustible gas 88; while the ambient fresh air 85 is pressurized by the intake air compressor 58 to produce compressed intake air 86. Both compressed intake combustible gas 88 and compressed intake air 86 are mixed within the intake combustible mixing chamber 59 to form a gas generator combustible gas mixture 89, which fuels both pulsating hot flue gas generation apparatus 10 and 1 1 through the intake valve 30.

[0071] In Figure 3, once the ignition of the gas generator combustible gas mixture 89 takes place within the combustion chamber 19 of cylinder 16 due to spark 55, the just generated combustion gases 90 flow as discharge combustion gases 91 from the combustion component set 15 to the mixing chamber 61 of the cooling component set 60 of the preferred embodiments of the pulsating hot flue gas generation apparatus 10 and 1 1 respectively, first through the discharge valve 36 and then through the exit check valve 46.

[0072] Immediately, as soon as the pressure at discharge end of the exit check valve 46 becomes greater than the pressure at the intake end thereof, the discharge valve 36 closes; when this occurs, the exhaust valve 48 opens allowing for the remaining generated combustion gases 90 left within the combustion chamber 19 of cylinder 16 to escape as gas generator cylinder exhaust gases 92 towards the atmosphere as depicted in Figure 1 for the preferred embodiment of pulsating hot flue gas generation apparatus 10 or to the intake end of the gases mixing chamber 82 for the preferred embodiment of pulsating hot flue gas generation apparatus 1 1 shown in Figure 2.

[0073] In the first preferred embodiment of pulsating hot flue gas generation apparatus 10 (Figure 1 ) the discharge combustion gases 91 produced by means of the preferred embodiment of the combustion component set 15 are combined with the pressurized fresh ambient air 85 within the mixing chamber 61 of the cooling component set 60. In this preferred embodiment, the power cylinder exhaust gases 94 produced by the power cylinders, regardless of the chemical composition of the power cylinder combustion gas mixture 81 , together with the gas generator cylinder exhaust gases 92, are both expelled to the atmosphere.

[0074] In the second preferred embodiment of pulsating hot flue gas generation apparatus 1 1 (Figure 2) the discharge combustion gases 91 produced by means of the preferred embodiment of the combustion component set 15, the power cylinder exhaust gases 94 produced by the power cylinders (only when the power cylinder combustion gas mixture 81 of the internal combustion engine is the same as the combustion gas mixture 89 of the flue gas generator cylinders), the optional hot air 95 coming from the air-cooled radiator of the engine's own cooling system, together with fresh air 85 are first mixed and cooled within a gases mixing chamber 82 (could be any heat exchanger means) to a temperature below the air compressor's 84 maximum manufacturer established intake temperature. The cooled gases mixture 97 exiting the gases mixing chamber 82 are pressurized by cooled gas compressor 84. The compressed gases 93 leaving cooled gas compressor 84 are discharged into the mixing chamber 61 of the cooling component set 60.

[0075] When thoroughly mixing gases (gas generation exhaust gases 92, power cylinder exhaust gases 94, hot air from engine's own cooling system 95 and ambient air 85) with different volume flow rates and densities within gases mixing chamber 82, its volume 80 establishes the minimum residency time frame required in order to avoid condensation; therefore, in order to prevent the entraining of liquid into the gas compressor 84 due to an excessively high mixed gases velocity, the gas mixing chamber 82 where the hot gases are mixed and cooled, must have a minimum gases mixing chamber diameter 78 established by the volume flow and density of said mixed gases and a minimum gas mixing chamber height 79 of one and a half times said minimum gases mixing chamber diameter 78. The gases mixing chamber 82 that takes into consideration the established criteria for determining the minimum gases mixing chamber height 79 and minimum gases mixing chamber diameter 78, will produce the gases mixing chamber volume 80.

[0076] In both preferred embodiments of the pulsating hot flue gas generation apparatus 10 and 1 1 , the flue gases 98 are produced by cooling to the user specified temperature, the combination of compressed gases 93 and discharge gases 91 within the mixing chamber 61 of the cooling component set 60.

[0077] The already cooled to the user specified temperature flue gases 98, flow from the cooling component set 60 to the well’s 99 wellhead. These flue gases 98 must flow through several sensors and meters before it enters the well’s 99 wellbore. These sensors are basically: (i) a temperature sensor 67 which signals the temperature controller 72 that controls the amount of compressed fresh ambient air 85 that is to be mixed with the discharge gases 91 to cool and adjust the flue gases 98 temperature to the user established temperature, (ii) a gas emission sensor (or a chromatograph) 70 that measures the flue gases 98 emissions and signals the fresh air volume rate control 74 to adjust the percentage of air in the gas generator combustible gas mixture 89, in order to assure that such emissions are below the maximum levels established by the Environmental Protection Agency (EPA) or other equivalent agency that is responsible for the air quality in a specific jurisdiction, (iii) a pressure sensor 69 which measures the reigning pressure and signals the control panel 73 to make adjustments to the reciprocating actuator means 56 in order to change, if necessary, the number of strokes per unit of time, and optionally, (iv) a volume rate meter 68 which signals the control panel 73 of the amount of flue gases 98 that are being injected into the well's 99 wellbore. This last measurement provided by the volume rate meter 68 allows the operator to know the total volume of flue gases 98 that has been injected into the formation surrounding said well’s 99 wellbore.

[0078] The preferred embodiments of the pulsating flue gas generation apparatus 10 and 1 1 respectively, may be embodied by one or several cylinders. For simplicity purposes, all explanations in this invention patent will be provided for one cylinder, with the understanding that the concepts and claims are extensive to the actual number of cylinders being implemented.

[0079] The preferred embodiment of the combustion component set 15 that appears in Figure 3, is basically constituted by: (i) a cylinder 16, (ii) a piston 21 that reciprocates within said cylinder 16 under actuation thereof by link 28 of any reciprocating actuator means 56, either mechanically (such as a crankshaft or a rack and pinion), pneumatically (such as a pneumatic cylinder), hydraulically (such as a hydraulic cylinder), or any other means that can provide a reciprocating motion to said piston 21 , and (iii) a cylinder head 24 with a sparkplug 54 and affixed suction 30, exhaust 48 and discharge 36 valves.

[0080] The intake valve 30 will be closed when the intake valve head's sealing surface 33 makes a hermetic contact with its corresponding intake valve seat's sealing surface 32. Similarly, the discharge valve 36 will be closed when the discharge valve head's sealing surface 38 makes a hermetic contact with its corresponding discharge valve seat's sealing surface 39. Likewise, the exhaust valve 48 will be closed when the exhaust valve head's sealing surface 51 makes a hermetic contact with its corresponding exhaust valve seat's sealing surface 50. All the valves will open when their valve head's sealing surfaces are separated from their corresponding valve seat's sealing surface. Within cylinder 16 there is a combustion chamber 19 bordered by the inner cylinder surface 17 of cylinder 16, the piston compression side 22 of piston 21 and the cylinder head compression side 25 of said cylinder head 24.

[0081] A feature of the preferred embodiment of the combustion component set 15 is that the outer cylinder surface 18 of cylinder 16, as well as interconnected water passages 26 within the cylinder head 24, are being cooled with water or any other coolant by the engine's own cooling system, which may include a fan cooled radiator or any other type of heat exchanger.

[0082] In the preferred embodiments of the pulsating flue gas generation apparatus 10 and 1 1 respectively, the stoichiometric gas generator combustible gas mixture 89, with an additional percentage of Oxygen (O2) in order to assure that there is complete combustion, enters the combustion chamber 19 through the intake valve 30 located at the cylinder head 24 until the established volume of the combustion chamber 19 is substantially filled with said gas generator combustible gas mixture 89. This gas generator combustible gas mixture 89 is pre-compressed to the user-specified pressure which should be established by the equivalent compression ratio (the compression ratio that a combustion chamber would have in any ordinary internal combustion engine), the pressure required at the well’s 99 wellhead to attain the downhole pressure at the formation surrounding the well’s 99 wellbore and finally the composition of said gas generator combustible gas mixture 89. Depending on said gas generator combustible gas mixture 89, the pre-compression should be typically between a few psi above atmospheric pressure: for example, the minimum could be established at around 20 psi, and the maximum at around 250 psi (these are non-limiting reference values, since the pressure limits may be varied). When the ignition of the pre-compressed gas generator combustible gas mixture 89 within the combustion chamber 19 takes place, by means of a spark 55 produced by sparkplug 54, the pressure of the combustion gases 90 produced (CO2, N2 and H2O) suddenly increases several times (typically between 4 and 15 times the precompression pressure, depending on the combustion chamber 19 dimensional parameters and the gas generator combustible gas mixture 89 used). When combustion takes place, the intake valve 30, the discharge valve 36 and the exhaust valve 48 are all closed, and since the gas generator combustible gas mixture 89 already occupies a large fraction of the overall available combustion chamber 19 volume, in novel accordance with the present invention, the expanding combustion gases 90 can only escape through said discharge valve 36 affixed to the cylinder head 24, and then through exit check valve 46 into the mixing chamber 61 of the cooling component set 60 in Figures 1 and 2. Due to the fact that the volume 65 of said cooling component set 61 is considerably larger than the volume 20 of the combustion chamber 19, the pressure and the temperature will drop significantly to a lesser value. With combustion taking place with each stroke of the piston's 21 reciprocating motion, the pressure at the mixing chamber 61 , as well at the well's 99 wellhead and in turn at the formation surrounding the well’s 99 wellbore, will increase with each stroke of the induced reciprocating motion producing an accumulative effect until the user-specified maximum pressure of the whole system is reached. When this occurs a pressure sensor 69 will send a signal to the flue gas generator control panel 73, in order to maintain this specific pressure condition until the user established flue gas injection volume is attained.

[0083] In the preferred embodiments of the pulsating flue gas generation apparatus 10 and 1 1 respectively, an exit checkvalve 46 that holds the backpressure of the cooling component set 60 may be implemented, depending on whether Case 1 : the discharge valve 36 is pre-loaded, or Case 2: the discharge valve 36 is actuated by any other means. In Case 1 , the implementation of exit check valve 46 is optional and is basically implemented mostly as a safety feature since the discharge valve 36 by itself could do the job of holding the backpressure of the cooling component set 60 during the discharge stage of the pulsating flue gas generator 10; however, in Case 2, said discharge valve 36 is actuated by any other means, therefore exit check valve 46 is no longer optional since now it becomes necessary for this valve to hold back the pressure of the cooling component set 60 during the discharge stage of the flue gas generator 10. Furthermore, in Case 1 , as soon as the discharge valve 36 is closed, the exhaust valve 48, whose stem 49 may be actuated by any means, will open allowing for the remaining combustion gases 90 within combustion chamber 19 to be evacuated as piston 21 moves towards its nearest position to the cylinder head 24; while in Case 2, the discharge valve 36 will be kept open by any means regardless of whether the exit check valve 46 is open or closed, but as soon as the exit check valve 46 is closed, the exhaust valve 48, whose stem 49 may be actuated by any means, will open so that the combustion gases 90 that remain in the said combustion chamber 19 are evacuated as the piston 21 moves towards the nearest position to the cylinder head 24. Moreover, in Case 1 , the discharge valve 36 will close as soon as the force exerted by the combustion chamber 19 pressure becomes lower than the pressure produced by the pre-load acting on the discharge valve stem 37; but in Case 2, the discharge valve 36 will close when an actuator means forcibly pushes said discharge valve stem 37. In both cases, during said discharge stage, the discharge valve 36 will be closed, while the intake valve 30 remains closed.

[0084] The cylinder head 24, in addition to the intake, discharge and exhaust valves 30, 36 and 48 respectively, has a sparkplug 54 which produces a spark 55 when the piston 21 is near its farthest position from the cylinder head 24 and a large fraction (or substantially all) of the volume 20 of the combustion chamber 19 is filled with the pressurized gas generator combustible gases mixture 89. Establishment of when the ignition produced by spark 55 should take place, is in principle determined by the velocity at which the combustion of the pressurized gas generator combustion gases mixture 89 within combustion chamber 19 occurs. What is important, is that the combustion must be complete by the time the discharge valve 36 is forcibly opened due to the sudden volume expansion and pressure increase produced by said combustion. The ignition timing may be user controlled so that no flare should exit the combustion chamber 19 through the discharge valve 36.

[0085] The intake valve 30, whose stem 31 may be actuated by any means, will be open during the suction stage of both pulsating flue gas generator apparatus 10 and 1 1 , that is when the piston 21 is moving between its nearest position to the cylinder head 24 to its farthest position therefrom, allowing for the pressurized gas generator combustible gas mixture 89 to enter the combustion chamber 19 within cylinder 16. Once piston 21 is near the end of the suction stage, said intake valve 30 will close. While all of this occurs during said suction stage, the exhaust valve 48 and the discharge valve 36 are both in their closed state. Once the piston 21 is near its farthest position from the cylinder head 24, and the intake valve 30, the exhaust valve 48 and the discharge valve 36 are all closed, the sparkplug 54 will produce a spark 55 that will ignite the compressed gas generator combustible gas mixture 89 producing the generated combustion gases 90. When this occurs the pressure within the combustion chamber 19 abruptly increases from a preset compression pressure to a very high pressure. Since the combustion chamber 19 is totally enclosed, the just generated combustion gases 90 can only escape through the discharge valve 36. This discharge valve 36 may be preloaded so that it will not open with the compressed pressure of the gas generator combustible gas mixture 89 during the suction stage; but when ignition occurs, with the sudden increase of pressure, said discharge valve 36 will definitively open, allowing for the expanding combustion gases 90 to flow through exit check valve 46 from the relatively small volume 20 of combustion chamber 19 into the very large volume 65 of the mixing compartment 61 of cooling component set 60. Therefore, once said discharge valve 36 opens, the pressure within chamber 19 will immediately drop. Furthermore, the temperature of the expanding combustion gases 90 will also abruptly decrease due to the above-mentioned volume change and also due to the engine's own cooling system.

[0086] It should be clear that in the preferred embodiment of the combustion component set 15 of the pulsating hot flue gas generation apparatus 10 and 11 , the intake valve 30 and the exhaust valve 48 will open and close, through actuation by any means known or available to those skilled in the art, while the discharge valve 36 will open by the force produced by the sudden pressure increase of the expanding generated combustion gases 90, and will close in Case 1 , due to the effect of a preload acting on the valve stem 37 which may be spring-loaded by spring 42 (or forced by any other means) even before the pressure at both sides of the discharge valve 36 becomes equal, and in Case 2, said discharge valve 36 will close when an actuator forcibly pushes its stem 37. The exit check valve 46 will close when the pressure at its discharge end becomes greater that the pressure at its intake end.

[0087] The generated combustion gases 90 that remain within the combustion chamber 19, after the discharge combustion gases 91 have passed beyond the discharge valve 36 and in turn through the exit check valve 46, are evacuated as exhaust gases 92 through the exhaust valve 48 during the exhaust stage, particularly by means of piston 21 as it moves from its farthest position from the cylinder head 24 to its nearest position thereto.

[0088] Specifically in the preferred embodiment of the pulsating flue gas generation apparatus 1 1 in Figure 2, if the reciprocating motion induced to the piston 21 is provided by an internal combustion engine, where the power cylinder combustible gas mixture 81 has exactly the same chemical composition as the gas generator combustible gas mixture 89 used for the pulsating flue gases generation, then its power cylinder exhaust gases 94 may also be diverted towards the intake end of the gases mixing chamber 82. It should be clear, that this setup takes complete advantage of all combustion gases generated.

[0089] In case the power cylinder combustible gas mixture 81 of the internal combustion engine is different from the gas generator combustible gas mixture 89 used for the pulsating flue gas generation, said power cylinder exhaust gases 94 should be discarded by any other means. Naturally, nothing needs to be discarded if another type of reciprocating motion actuator is implemented (such as a pneumatic or hydraulic reciprocating means), and doesn’t rely on a combustion-based energy source for its operation.

[0090] In case the preferred embodiment of the combustion component set 15 is cooled by any heat exchanger means, such as a fan cooled radiator; optionally the hot air 95 generated by the engine's heat exchange process can also be diverted totally or partially to the intake end of the gases mixing chamber 82.

[0091] Since piston 21 reciprocates within cylinder 16 of the preferred embodiment of the combustion component set 15, a pulsating effect will be induced to the just-produced discharge combustion gases 91 . The frequency of the pulsating effect will depend on the number of strokes per unit of time provided by the reciprocating actuator means 56 (see Figures 1 and 2). It is important to clarify, that if the number of strokes per unit of time is kept very low, in accordance with the preferred embodiments of the pulsating flue gas generation apparatus 10 and 1 1 respectively, it is very unlikely to reach a resonant condition in the production tubing, so no damage or fatigue is expected to occur downhole or to any of the surface facilities. The pulsating effect should rather aid in the mobility of the flue gases within the oil well formation. Additionally, a slight agitation should also be expected to occur which in turn could facilitate the flow of the oil from the surrounding formation into the well's 99 wellbore.

[0092] It should be understood that the pressure between the exit check valve 46 right after the discharge valve 36 and the well's 99 wellbore, will increase slightly with each combustion cycle and will accumulate over a specific time period. Once the accumulated pressure reaches a preset pressure value, the system will continue to inject flue gases 98 at this pressure until the user specified volume of gases within the formation is reached. Should the user consider that additional pressure is required, an external compressor could also be implemented.

[0093] In both preferred embodiments of the pulsating flue gas generation apparatus 10 and 1 1 , the compressed gases 93 (air in Figure 1 and mixture of gases in Figure 2) that exits said air compressor 84 through its exhaust end, enters the mixing chamber 61 of the cooling component set 60. It is important to point out that the cooling component set 60 can have any other configuration or could be any other type of heat exchanger than the one shown in Figures 1 and 2; since its sole purpose, is to lower the flue gases 98 temperature.

[0094] In view of the fact that in both preferred embodiments of the pulsating flue gas generation apparatus 10 and 1 1 , the temperature of the generated combustion gases 90 produced by the combustion of the gas generator combustible gas mixture 89 within the combustion chamber 19, by the time they reach, as discharge combustion gases 91 , the mixing chamber 61 of the cooling component set 60, are typically higher than the user- established maximum temperature (which depends on the well’s 99 wellbore completion temperature limitations), the simplest way to control said temperature is by mixing this discharge combustion gases 91 together with cooler compressed gases 93 until the user- established maximum temperature is reached and maintained. Therefore, for the first preferred embodiment of the pulsating flue gas generation apparatus 10, the compressed gas 93 is simply fresh ambient air 85 compressed with compressor 84; while for the second preferred embodiment of the pulsating flue gas generation apparatus 1 1 , the cooler compressed gas 93 corresponds to a blend of hot gases (corresponding to: (i) the gas generator cylinder exhaust gases 92 evacuated from the combustion chamber 19 during the exhaust stage, (ii) the power cylinder exhaust gases 94 produced by the reciprocating motion actuator 56, only if it is an internal combustion engine that uses a power cylinder gas mixture 81 with the same chemical composition as the gas generator combustible gas mixture 89, and (iii) optionally, the hot air 95 coming from the air cooled radiator of the engine's own cooling system) which are first mixed and then cooled by any means within gases mixing chamber 82 to produce a cooled gases mixture 97 whose temperature must be below the maximum manufacturer established intake temperature for compressor 84.

[0095] In both preferred embodiments of the pulsating flue gas generation apparatus 10 and 1 1 , the compressed gas mixture 93 that leaves the compressor 84, as well as, the discharge combustion gases 91 , are both injected through their own gas diffuser 62 (such as a spray nozzle) or any other means into the mixing chamber 61 of cooling component set 60 in order to cool the flue gases 98 temperature, until the user established temperature is reached. It should be noted that, only if necessary, further cooling might be provided by a cooling tower or any other type of heat exchanger.

[0096] Accordingly, in both preferred embodiments of the pulsating flue gas generation apparatus 10 and 1 1 , the volume rate per day of hot flue gases 98 that could be injected into the well’s 99 wellbore every 24 hours is established by (i) the volume 20 (see Figure 3) of the combustion chamber 19 within the cylinder 16, (ii) the number of cylinders that are used for the generation of combustion gases 90, and (iii) the number of strokes per unit of time. This volume rate is also adjustable since the number of strokes per unit of time can be easily controlled.

[0097] The preferred embodiment of the combustion component set 15 of both pulsating hot flue gas generation apparatus 10 and 11 differs substantially from any internal combustion engine, regarding the actuation of piston 21 , the configuration of the cylinder head 24 and what is completely novel, the implementation and location of the discharge valve 36 affixed to its cylinder head 24. In said preferred embodiment of the combustion component set 15, the piston 21 , actuated by actuator link 28 or any other means (could be a link connected to a crankshaft, the rack of a rack and pinion actuator or any other means), moves reciprocally within cylinder 16 having a sliding contact between the piston outer cylindrical surface 23 of piston 21 and the cylinder inner cylindrical surface 17 of cylinder 16. Sealing between these two sliding cylindrical surfaces can be provided by any means (such as piston rings). In this case, the piston 21 could be composed of a single piece and the piston compression side 22 of said piston 21 does not allow gas passage to the other side of the referred piston 21 .

[0098] The operation of the intake valve 30 and the exhaust valve 48 and how they are guided in the preferred embodiment of the combustion component set 15 of both pulsating hot flue gas generation apparatus 10 and 11 , is well known by those skilled in the art. Both the intake valve head's sealing surface 32 and the exhaust valve head's sealing surface 50 located opposite the intake valve head high-pressure end 34 and the exhaust valve head high-pressure end 52 make a hermetic seal with its intake valve seat's sealing surface 33 and its exhaust valve seat's sealing surface 51 respectively. As expected, intake valve 30 and exhaust valve 48 open when intake valve stem 31 and exhaust valve stem 49 move the intake valve head's sealing surface 33 and the exhaust valve head's sealing surface 51 towards the combustion chamber 19 apart from its intake valve seat's sealing surface 32 and its exhaust valve seat's sealing surface 50 respectively, which are affixed to the cylinder head 24; however, the operation of the discharge valve 36 also affixed to cylinder head 24 is backward from the operation of the intake valve 30 and exhaust valve 48, since the discharge valve head’s sealing surface 38 is located at the discharge valve head high-pressure end 40 under the direct effect of the generated combustion gases 90 produced within chamber 19 during the combustion of the combustible gases mixture 89. Here, since stem 37 is preloaded typically by spring 42 or by any other means, the discharge valve head’s sealing surface 38 contacts the discharge valve seat's sealing surface 39 while the combustion chamber 19 is being filled with the combustible gases mixture 89 at a pre-established pressure during the suction stage of both pulsating hot flue gas generator apparatus 10 and 1 1 . As soon as the combustible gases mixture 89 is ignited due to spark 55 produced by sparkplug 54, the just generated very high pressure will immediately open said discharge valve 36, by moving the discharge valve head’s sealing surfaces 38 apart from its discharge valve seat's sealing surface 39.

[0099] As soon as the exit check valve 46 in the preferred embodiment of the combustion component set 15 of pulsating hot flue gas generation apparatus 10 and 1 1 closes, which occurs when the pressure at discharge end of said exit check valve 46 is greater than the its intake end pressure, the exhaust valve 48 opens allowing for the remaining generated combustion gases 90 within combustion chamber 19 to be pushed out as gas generator cylinder exhaust gases 92 by piston 21 as it moves towards the cylinder head 24. When the piston 21 is very near to the inner cylinder head compression side 25 of cylinder head 24, the exhaust valve 48 closes. At the instant said piston 21 changes its direction of motion, the intake valve 30 opens, thus starting the suction stage of both pulsating hot flue gas generator apparatus 10 and 1 1 , and thereby repeating the overall operation cycle.

[0100] Once the discharge combustion gases 91 pass through exit check valve 46 located between the discharge valve 36 and the mixing chamber 61 of the cooling component set 60, these gases, together with the compressed gases 93 (ambient air 85 in Figure 1 and exhaust gases 92 and 94 and optionally hot air 95 from the cooling system of the engine in Figure 2) and optionally other gas or substance 96 (such as Carbon Dioxide or any other gas or a corrosion inhibitor), enter through any type of gas diffuser 62 (or spray nozzle) into said mixing chamber 61 , where they will be cooled to the user-established temperature (typically at less than 300 °F for standard completions and up to 500 °F when Vacuum Insulated Tubing is used).

[0101] When thoroughly mixing gases with different volume flow rates and densities within a vessel, its volume establishes the minimum residency time frame required in order to avoid condensation; therefore, in order to prevent the entraining of liquid into the well's 99 wellhead due to an excessively high flue gases 98 velocity, the gas mixing chamber 61 of said cooling component set 60, regardless of its inner configuration, where the hot gases are mixed and cooled, must have a minimum gas mixing chamber diameter 63 established by the volume flow and density of said flue gases 98 and a minimum gas mixing chamber height 64 of one and a half times said minimum gas mixing chamber diameter 63. The cooling component set 60 that takes into consideration the established criteria for determining the minimum gas mixing chamber height 64 and minimum gas mixing chamber diameter 63 of the vessel, will produce the cooling chamber volume 65.

[0102] The already cooled, to the user specified temperature, hot flue gases 98 that leave the cooling component set 60, of the first preferred embodiment of the pulsating hot flue gas generation apparatus 10 is comprised by: (i) the discharge combustion gases 91 produced during the combustion of the gas generator combustible gas mixture 89 within the combustion chamber 19, (ii) the compressed ambient air 93, and (iii) optionally any other gas or substance 96; while the same hot flue gas 98 that leaves said cooling component set 60, of the second preferred embodiment of the pulsating hot flue gas generation apparatus 1 1 is comprised by: (i) the same discharge combustion gases 91 produced during the combustion of the gas generator combustible gas mixture 89 within the combustion chamber 19, (ii) the compressed gases 93 comprised by the gas generator cylinder exhaust gases 92, (iii) the fresh ambient air 85, (iv) the optional hot air that comes from the engine's own cooling system 95, (v) the optional power cylinder exhaust gases 94, and (vi) optionally any other gas or substance 96.

[0103] Once the already cooled hot flue gases 98 leave the cooling component set 60, and pass through the temperature sensor 67, gas emission sensor 70, pressure sensor 69, and the volume rate measuring devise or recorder 69, they will enter the well’s 99 wellhead. Since the combustion of the gas generator combustible gas mixture 89 occurred in the combustion chamber 19 within cylinder 16 of an apparatus with a reciprocating motion of its piston 21 (or pistons), the generated hot flue gases 98 will have a pulsating effect where each pulse produces an accumulative pressure. In other words, the pressure increases slightly with each stroke of piston 21 , and the downhole end of the well's 99 wellbore will experience these pulses as the flue gas 98 flows into the formation surrounding said well's 99 wellbore. These pulses may produce a slight agitation within the formation, which should facilitate the flow of the oil to the referred downhole end of the well's 99 wellbore, further aiding in the oil production. When the formation surrounding the well's 99 wellbore reaches a user-specified pressure, the pressure sensor 69 located between the cooling component set 60 and the well’s 99 wellhead will send a signal to the control panel 73 of either pulsating hot flue gas generation apparatus 10 or 1 1 , to maintain this pressure until the specified volume of flue gas 98 is reached.

[0104] Operation of the Flue Gas Generator for both preferred embodiments of the pulsating hot flue gas generation apparatus 10 and 11 where the Discharge Valve 36 is affixed to its Cylinder Head 24

[0105] The operation logic developed for both pulsating hot flue gas generation apparatus 10 and 1 1 , according to the preferred embodiment of the combustion component set 15 is completely different from any other internal combustion engine, in the sense that there are three distinct stages. These are the suction stage, the discharge stage and the exhaust stage.

[0106] During the suction stage, the combustion chamber 19 is substantially filled with a pressurized gas generator combustible gas mixture 89 equivalent to what would have been the compression pressure (corresponding to the compression ratio) generated in the compression cycle of any internal combustion engine with a reciprocating piston.

[0107] Once the piston 21 is nearing the end of its suction stage and said combustion chamber 19 is almost completely full with the compressed gas generator combustible gas mixture 89, at least one sparkplug 54 will produce a spark 55 that will ignite said compressed gas generator combustible gas mixture 89 which will generate a sudden pressure surge, depending on said gas generator combustible gas mixture 89 and the initial precompression pressure, which forcibly opens the discharge valve 36 starting the discharge stage.

[0108] Additional to the pressure increase, simultaneously a very large gas volume expansion of the generated combustion gases 90 will occur. This increase in the combustion gases’ volume (which will be several times the volume 20 of the cylinder combustion chamber 19, depending on the gas characteristics, compression ratio, temperature and initial pressure) has to expand somewhere. Since the combustion chamber 19 is completely enclosed and cannot change in dimensions, the just generated combustion gases 90 within combustion chamber 19 will seek to escape as discharge combustion gases 91 through the just opened discharge valve 36, rushing said discharge combustion gases 91 towards the cooling component set 60.

[0109] Apart from the expanding generated combustion gases 90, as soon as piston 21 changes its direction of motion as it now moves towards its nearest position to the cylinder head 24, it will start to push the remaining high pressure generated combustion gases 90 out of the combustion chamber 19, still as discharge combustion gases 91 , until the pressure at discharge end of said exit check valve 46 becomes greater than its intake end pressure, thus ending the discharge stage. As soon as this occurs, (i) said exit check valve 46 closes, (ii) the discharge valve 36 will also close, and (iii) the exhaust valve 48 opens, beginning the exhaust stage, allowing for the remaining generated combustion gases 90 to be evacuated as gas generator cylinder exhaust gases 92 from the combustion chamber 19. In the preferred embodiment of the combustion component set 15, said discharge valve 36 will close as soon as the preload forces acting on the stem 37 of the referred discharge valve 36 overcome the force produced on the discharge valve head high pressure end 34 by the pressure within the combustion chamber 19. Immediately as soon as the discharge valve 36 closes, the exhaust valve 48 opens; thus, as piston 21 keeps moving towards cylinder head 24 the exhaust valve 48 will remain open. Finally, said exhaust valve 48 will close right before the piston 21 reaches the closest position with respect to the cylinder head 24, thus ending the exhaust stage.

[0110] Immediately, when piston 21 changes the direction of motion, and now moves away from the cylinder head 24, the intake valve 30 opens allowing the pre-compressed gas generator combustible gases mixture 89 to enter into the combustion chamber 19 through intake valve 30, thus beginning again the suction stage, thereby repeating the overall operation cycle.

[0111] The preferred embodiment of the combustion component set 15 of both pulsating hot flue gas generation apparatus 10 and 11 cannot be considered a compressor as such, since the sudden pressure increase is due to the expansion of the generated combustion gases 90 right after ignition of the gas generator combustible gas mixture 89 within the combustion chamber 19, and not due to mechanical force produced by the piston 21. Neither can said preferred embodiment of the combustion component set 15 be considered an internal combustion engine as such, since the expansion of generated combustion gases 90 within said combustion chamber 19 practically does not act upon said piston 21 to produce any torque. It is some sort of hybrid whose sole purpose is limited to producing hot flue gases 98. In this concept, the motion of piston 21 may be provided by any independent reciprocating means (either mechanical, pneumatic, hydraulic, or any other).

[0112] Figure 4 present the operation sequence related to the preferred embodiment of the combustion component set 15 of both pulsating hot flue gas generation apparatus 10 and 1 1 , where all the stages discussed above are depicted. In this figure, the intake valve 30 is “I”, the exhaust valve 48 is “E”, the discharge valve 36 is “D” and the exit check valve 46 is “C”. Using this nomenclature together with the numbers that appear in Figures 1 and 2, the following phases may be described:

[0113] Phase (a) - Beginning of Suction Stage: both the exhaust valve 48 (E) and the discharge valve 36 (D) are closed while the intake valve 30 (I) opens allowing the pre-compressed gas generator combustible gas mixture 89 to enter into the combustion chamber 19 of cylinder 16 as the piston 21 starts the suction stage when it begins to move away from cylinder head 24.

[0114] Phase (b) - End of Suction Stage: both the exhaust valve 48 (E) and the discharge valve 36 (D) remain closed as the piston 21 is nearing the farthest distance from the cylinder head 24 almost ending the suction stage. Right before the end of the suction stage, the intake valve 30 (I) closes and the combustion chamber 19 is almost completely full with the pre-compressed gas generator combustible gas mixture 89.

[0115] Phase (c) - Combustion: while the exhaust valve 48 (E), the discharge valve 36 (D) and the intake valve 30 (I) remaining closed, and as piston 21 is even closer to the farthest distance from the cylinder head 24, sparkplug 54 ignites with spark 55 the pre- compressed gas generator combustible gas mixture 89 which in turn generates the combustion gases 90. As the combustion gases 90 are produced immediately within the combustion chamber 19, a very high-pressure surge and a sudden increase in volume of the combustion gases 90 occurs.

[0116] Phase (d) Discharge Stage: both the intake valve 30 (I) and the exhaust valve 48 (E) remain closed. Once the ignition 55 of the pre-compressed gas generator combustible gas mixture 89 takes place within combustion chamber 19, and with the piston 21 now even closer to the to the farthest distance from the cylinder head 24 (but not yet at said farthest distance), due to the very high-pressure surge and the sudden increase in combustion gases 90 volume, the discharge valve 36 (D) forcibly opens, thus beginning the discharge stage. The generated combustion gases 90 rush out of the combustion chamber 19 through the discharge valve 36 (D), and in turn open the exit check valve 46 (C) since the counter-pressure on the other side of exist check valve 46 (C) is at a lower pressure than the pressure of the generated combustion gases 90. Once the generated combustion gases 90 pass through the discharge valve 36, they become the discharge combustion gases 91 . The timing for the ignition 55 should be such that by the time the discharge valve 36 (D) opens, the combustion of the pre-compressed gas generator combustible gas mixture 89 within combustion chamber 19 must be complete, so that there is no flare passing through said discharge valve 36 (D), only the just generated combustion gases 90. Once the pressure within the mixing chamber 61 of the cooling component set 60 becomes greater than the pressure within combustion chamber 19 of the combustion component set 15, both the discharge valve 36 (D) and said exit check valve 46 (C) will close, thus ending the discharge stage.

[0117] Phase (e) - Beginning of the Exhaust Stage: while the intake valve 30 (I) remains closed and soon after the discharge valve 36 (D) closes, the exhaust valve 48 (E) opens allowing for the remaining generated combustion gases 90 within combustion chamber 19 to escape through said exhaust valve 48 (E). The generated combustion gases 90 once they leave the combustion chamber 19 through the exhaust valve 48 (E) become the gas generator cylinder exhaust gases 92. When the exhaust valve 48 (E) opens, the exhaust stage begins as the piston 21 continues moving towards the cylinder head 24. Phase (f): End of the Exhaust Stage: while both the intake valve 30 (I) and the discharge valve 36 (D) remain closed and piston 21 has substantially reached the nearest position with respect to the cylinder head 24, the exhaust valve 48 (E) now also closes, thus ending the exhaust stage.

[0118] Then once the piston 21 changes its direction of motion at its nearest position with respect to the cylinder head 24, the suction stage starts again as indicated in Phase (a), whereupon the overall operation cycle is repeated.

[0119] The preferred embodiment of the combustion component set 15 of both pulsating hot flue gas generation apparatus 10 and 11 could be actuated by any reciprocating means as has already been described; thus, one of the possible means could be an internal combustion engine with several power cylinders, of which one or more of said power cylinders could be transformed into flue gas generation cylinders 16. The power cylinders would actuate the piston 21 within the flue gas generator cylinders 16 with the same internal combustion engine crankshaft. Here, the combustion chamber 19 within each flue gas generator cylinder 16 could be substantially filled with the pre-compressed combustible gases mixture 89 during the suction stage, thus providing after the ignition 55 takes place, the maximum volume of generated combustion gases 90 in each crankshaft revolution per minute (RPM).

[0120] At the time the combustion process takes place in the preferred embodiment of the combustion component set 15 of both pulsating hot flue gas generation apparatus 10 and 1 1 , a specific volume of hot flue gases 98 is injected into the well’s 99 wellbore with each explosive pulse. This process is cumulative and therefore it can be asserted that the volume of expanding combustion gases 90 and the pressure generated in each explosion, is cumulative. It should be understood that through this process of progressive pressurization, the well’s 99 wellhead continually experiences a positive pressure that is the product of the overpressure wave generated at the time of the ignition within each combustion chamber 19, which generates a pulsating effect at the formation surrounding the well’s 99 wellbore ensuring its progressive pressurization. The preferred embodiment of the combustion component set 15 of both pulsating hot flue gas generation apparatus 10 and 1 1 described above will effectively produce the necessary hot flue gases 98 at the user established: (i) temperature, in order to lower the crude oil viscosity, thus facilitating its mobility from the formation to the wellbore, (ii) pressure, to re-pressurize the formation surrounding the well's 99 wellbore, (iii) volume rate, to attain in a predetermined number of days the desired heat stimulation volume, and (iv) pulsation frequency, to aid in faster penetration of the flue gases into the formation and offer slight agitation to further facilitate the crude oil mobility from the formation to the well's 99 wellbore. Apart from these most important parameters, the combustion gases provide an additional benefit in the sense that in their composition, there is a percentage of: (i) Carbon Dioxide (CO2) which is highly soluble in the crude oil further aiding in lowering its viscosity and facilitating its extraction, and (ii) Nitrogen (N2) which offers very low solubility with the crude oil, but has a significant effect in pushing the oil from within the formation to the well's 99 wellbore.

[0121] There could be other valves and additional sensors provided between the cooling component set 60 and the well’s 99 wellhead, though they are not essential parts of either inventive pulsating hot flue gas generation apparatus 10 or 1 1 .

[0122] It is to be understood that the invention is not limited to the illustrations described and shown herein, which are deemed to be merely illustrative of the best mode of carrying out the invention, and which are susceptible to modification of form, size, arrangement of parts and details of operation. The invention rather is intended to encompass all such modifications which are within its spirit and scope as defined by the claims.

Claims

ClaimsThe description of the invention is considered a novelty and, therefore, what is contained in the following clauses are claimed as property:Claim 1 : A flue gas generation apparatus for the generation of pulsating hot flue gases to be injected into an oil well in order to increase formation pressure and lower crude oil viscosity to facilitate mobility of said crude oil towards a wellbore of said oil well, said apparatus including in combination: a combustion component set operable in reciprocating fashion to generate hot pulsating combustion gases and exhaust gases; and a cooling component set where generated hot pulsating combustion gases are mixed with other gases to produce cooled flue gases at a user-established temperature; wherein said combustion component set is comprised by at least one cylinder each having a respective piston and a respective cylinder head, and for each cylinder, at least one: (i) sparkplug, (ii) intake valve, (iii) exhaust valve, and (iv) discharge valve; wherein the cylinder has an outer cylinder surface, an inner cylinder surface that guides the piston and houses the combustion chamber, one end facing the cylinder head and another end facing oppositely thereof; wherein the combustion chamber is within the cylinder, which is bordered by the inner cylinder surface of the cylinder and respective high-pressure ends of the reciprocating piston and the cylinder head; wherein a volume of the combustion chamber is substantially filled with a precompressed combustible gas mixture throughout a suction stage in which the reciprocating piston moves from a position nearest the cylinder head to a position farthest from the cylinder head;wherein the respective high-pressure ends of the reciprocating piston and the cylinder head face the combustion chamber, and the cylinder head has a set of cylindrical valve guides that pass therethrough from the high-pressure end thereof to an opposing outer end, and at least one affixed sparkplug operable at the high- pressure end of the cylinder head; wherein the cylindrical valve guides of the cylinder head guide respective valve stems of: (i) the at least one intake valve, (ii) the at least one exhaust valve, and (iii) the at least one discharge valve; wherein the suction, exhaust and discharge valves of each cylinder are affixed to the respective cylinder head; wherein each intake, exhaust and discharge valve has a respective valve head carried on the respective valve stem, and each valve head has a respective sealing surface that closes the respective valve when said respective sealing surface contacts a corresponding sealing surface of a respective valve seat, and opens the respective valve when said respective sealing surface and said corresponding sealing surface are separated; wherein the valve head of each valve has a high-pressure end facing the combustion chamber and an opposite low-pressure end; wherein the sealing surface of the respective valve head of each of the intake and exhaust valves, and the corresponding sealing surface of the respective valve seat, are located at the low-pressure end of said each of the intake and exhaust valves, respectively; wherein the sealing surface of the respective valve head of the discharge valve, and the corresponding sealing surface of the respective valve seat, are located at the high-pressure end of said discharge valve;wherein an inner surface of each of the cylindrical valve guides slidingly contacts an outer surface of the respective valve stem of one of the suction, discharge and exhaust valves; wherein a separation distance that exists between the sealing surface of the respective valve head of the discharge valve and the corresponding sealing surface of the respective valve seat of the same discharge valve when said discharge valve is open is sufficiently large to handle a volume of combustion gases generated during combustion of the combustible gas mixture; wherein the piston lacks any openings therein that would communicate the high- pressure end thereof, which faces the combustion chamber, with an opposing low- pressure end thereof; wherein at a beginning of a stroke of reciprocating motion of the piston, the piston is at the nearest position to the cylinder head, and at an end of the stroke of the reciprocating motion is when said piston is at a farthest position from the cylinder head; wherein the reciprocating motion of the piston within the cylinder produces a suction stage, a discharge stage and an exhaust stage; wherein the suction stage occurs when during the reciprocating motion, the piston within the cylinder is moving away from the cylinder head and the intake valve is open allowing the entrance of the pre-compressed combustible gases mixture, while the discharge and exhaust valves are held closed; wherein the suction stage begins as soon as the intake valve opens, when the piston is slightly past the beginning of the stroke of the reciprocating motion as the piston starts to move from the nearest position to the cylinder head towards the farthest position from said cylinder head allowing for the pre-compressed combustible gases mixture to start filling the combustion chamber of the cylinder;wherein the suction stage ends as soon as the intake valve closes, when the piston is almost at the end of the stroke as the piston is near the farthest position from the cylinder head, thereby ceasing said filling of the combustion chamber with the precompressed combustible gases mixture; wherein within the combustion chamber, ignition of the pre-compressed combustible gases mixture produced by a spark occurs near the end of the stroke, when the suction, discharge and exhaust valves are all closed; wherein the timing for the ignition is such that the combustion of the pre-compressed combustible gases mixture is completed immediately before the discharge valve opens, preventing passage of any flare through said discharge valve; wherein the discharge stage begins when the discharge valve opens once the combustion of the pre-compressed combustible gases mixture is complete, due to sudden increase in pressure and expansion of the combustion gases, when the piston is short of reaching the end of the stroke, while the intake and exhaust valves remain closed; wherein as soon as the discharge valve opens, both a temperature and a pressure of the combustion gases are lowered while being discharged from the combustion chamber; wherein downstream of the discharge valve there is an exit check valve that holds back a downstream counterpressure; wherein the discharge valve is maintained in a closed state from which said discharge valve is openable when a pressure within the combustion chamber, acting on a surface area of the respective valve head of the discharge valve, imparts an opening force that exceeds a holding force by which said discharge valve is otherwise held closed; wherein the discharge stage ends while the piston moves toward the cylinder head and the discharge valve is closed by said holding force once the exit check valvecloses under drop of the pressure within the combustion chamber to less than the downstream counterpressure; wherein the exhaust stage begins when, during the reciprocating motion, the piston within the cylinder is moving toward the cylinder head and the exhaust valve opens once the discharge valve has closed, during which the intake valve remains closed; wherein the exhaust valve, when opened, allows remnant combustion gases left within the combustion chamber, to be evacuated from said combustion chamber during the exhaust stage; wherein the respective stem of the exhaust valve maintains closed the exhaust valve during the suction and discharge stages, and opens said exhaust valve during the exhaust stage; wherein the exhaust stage ends when the high-pressure end of the piston is at the position nearest to the high-pressure end of the cylinder head; wherein the inner surface of the cylinder as well as the valves affixed to the cylinder head, maintain the pressure produced within the combustion chamber by the combustion of the pre-compressed combustible gas mixture; wherein the exit check valve is located between the discharge valve and the mixing chamber of the cooling component set, allows flow of the combustion gases into said mixing chamber of the cooling component set when the pressure within the combustion chamber of the cylinder of the combustion component set is higher than a pressure within said mixing chamber of the cooling component set, and blocks return of gases from the mixing chamber to the combustion chamber when the pressure within the combustion chamber of the cylinder of the combustion component set is lower than the pressure within said mixing chamber of the cooling component set; wherein owing to opening of the exit check valve only when the pressure within the combustion chamber of the cylinder of the combustion component set is higher thanRECTIFIED SHEET (RULE 91.1 )the pressure within the mixing chamber of the cooling component set, the pressure within the mixing chamber of the cooling component set increases with every stroke of the reciprocating motion; wherein owing to increase of the pressure within the mixing chamber of the cooling component with said every stroke of the reciprocating motion, said increase of the pressure is transmitted to the wellhead through the flue gases; wherein the wellhead continually experiences a positive pressure that is a product of an overpressure wave generated at a time of the ignition within the combustion chamber of the cylinder, which generates a pulsating effect at a formation surrounding the wellbore ensuring progressive pressurization of said formation surrounding the wellbore; and wherein a pressure pulse frequency produced by the pulsating pressure effect of the flue gases, is dependent on the reciprocating motion rate imparted to the piston.Claim 2: The apparatus according to Claim 1 , wherein the cooling component set, where the generated hot pulsating combustion gases are mixed with said other gases to produce the cooled flue gases, comprises a fresh air compressor and a gas mixing chamber; wherein the fresh air compressor receives and compresses fresh ambient air to a pressure slightly above a wellhead pressure, where said wellhead pressure corresponds to summation of pressure losses from the cooling component set to a downhole formation surrounding the wellbore plus a well bottomhole pressure; wherein the fresh air compressor delivers said fresh ambient air into the gas mixing chamber at a temperature below the user-established temperature; wherein the gas mixing chamber is configured to assure a complete mixing of a flue gas mixture corresponding to a summation of: (i) the pulsating hot combustion gases flowing in from the at least one cylinder of the combustion component set, together with (ii) the compressed fresh ambient air from the compressor;wherein within the gas mixing chamber the flue gases are cooled until the user established temperature is reached and maintained; wherein the gas mixing chamber where the flue gases are cooled, in order to prevent entraining of liquid into a wellhead of the oil well due to an excessively high flue gases velocity, has a minimum gas mixing chamber diameter established by a volume flow and density of a chamber flue gases outlet stream and a minimum gas mixing chamber height of one and a half times said minimum gas mixing chamber diameter; wherein a volume of the gas mixing chamber of the cooling component set is a function of the minimum gas mixing chamber diameter and the minimum cooling gases mixing chamber height; wherein the volume of the gas mixing chamber of the cooling component set is sufficiently large to assure complete mixing of the hot pulsating combustion gases with the compressed fresh ambient air; and wherein the cooling gases mixing chamber has an outlet port where the cooled flue gases mixture leaves the cooling gases mixing chamber of the cooling component set first travels towards the wellhead, then onward through the wellbore and finally to a downhole end of the oil well in order to pressurize the downhole formation surrounding said wellbore.Claim 3: The apparatus according to Claim 1 , further comprising an engine with one or more power cylinders, wherein the cooling component set, where the generated hot pulsating combustion gases are mixed with other gases to produce the cooled flue gases, comprises a hot gases mixing chamber, a compressor and a cooling gases mixing chamber; wherein the hot gases mixing chamber is configured to assure a complete mixing of said other gases into a hot gases mixture, corresponding to a summation of: (i) the exhaust gases from the at least one cylinder of the combustion component set, (ii)additional exhaust gases from the one or more power cylinders, (iii) any incoming hot air from a fan cooled radiator of the engine, and (iv) incoming fresh ambient air, which are mixed with said generated hot pulsating combustion gases to form a hot gases mixture; wherein the hot gases mixing chamber cools the hot gases mixture to a temperature below a maximum intake temperature of the compressor; where the hot gases mixing chamber where the hot gases mixture is cooled, in order to prevent entraining of liquid into the compressor due to an excessively high hot gases velocity, has a minimum hot gases mixing chamber diameter established by a volume flow and density of a chamber hot gases outlet stream and a minimum hot gases mixing chamber height of one and a half times said minimum hot gases mixing chamber diameter; wherein the compressor receives the cooled hot gases mixture and performs compression thereof to a pressure slightly above a wellhead pressure of the oil well, which corresponds to a summation of pressure losses from the cooling component set to a downhole formation surrounding the wellbore plus a well bottomhole pressure; wherein the compressor delivers said cooled and compressed hot gases mixture at a temperature below the user-established temperature; wherein the cooling gases mixing chamber is configured to assure a completed mixing of a flue gas mixture corresponding to the summation of: (i) the pulsating hot combustion gases flowing in from the at least one cylinder of the combustion component set, together with (ii) the compressed and cooled hot gases mixture from the compressor; wherein the cooling gases mixing chamber cools the flue gas mixture until the user established temperature is reached and maintained;where the cooling gases mixing chamber where the flue gas mixture is cooled, in order to prevent entraining of liquid into a wellhead of the oil well due to an excessively high flue gases velocity, has a minimum cooling gases mixing chamber diameter established by a volume flow and density of said chamber flue gases outlet stream and a minimum cooling gases mixing chamber height of one and a half times said minimum cooling gases mixing chamber diameter; wherein a volume of the cooling component set is function of the minimum cooling gases mixing chamber diameter and the minimum cooling gases mixing chamber height. And wherein the cooling gases mixing chamber has an outlet port where the cooled flue gases mixture leaves the gases mixing chamber of the cooling component set and travels first towards the wellhead, then onward through the wellbore and finally to a downhole end of the wellbore in order to pressurize the formation surrounding said wellbore.Claim 4: The apparatus according to Claim 2 or 3, wherein a temperature sensor is located between the cooling component set and the wellhead, and controls flow of the fresh ambient air into the mixing chamber until the flue gas mixture leaving said cooling component set is at the user-established temperature.Claim 5: The apparatus according to any one of Claims 2 to 4, wherein a gas emission sensor or equivalent is located between the cooling component set and the oil well, and provides information required to control a chemical composition of the cooled flue gases being injected into the wellbore in order to assure that said cooled flue gases are within user-established composition targets.Claim 6: The apparatus according to any one of Claims 1 to 5, wherein a pressure sensor is located between the cooling component set and the oil well, and is operable to maintain operation of the combustion component set at a user-established well pressure.Claim 7: The apparatus according to any one of Claims 1 to 6, wherein a volume rate measurement device is installed between the cooling component set and the oil well, andmeasures a volume per day being injected into the wellbore, so that once a user- established volume is attained, automatic shut off of the combustion component set is triggered.Claim 8: The apparatus according to Claim 1 , further comprising an internal combustion engine whose crankshaft imparts the reciprocating motion to the piston of the combustion component set.Claim 9: The apparatus according to Claim 8, wherein the internal combustion engine comprises a plurality of cylinders, at least one of which embodies the at least one cylinder of the combustion component set, and at least one other of which is a power stroke cylinder of which a power stroke thereof forces rotation of a crankshaft of said internal combustion engine.Claim 10: The apparatus according to Claim 8 or 9, wherein the power stroke cylinder uses a same combustible gases mixture as the pre-compressed combustible gases mixture used by the at least one cylinder of the combustion component set, and additional exhaust gases generated by said internal combustion engine are recompressed, by a compressor, together with the exhaust gases from the at least one cylinder of the combustion component set and fresh ambient air.Claim 11 : The apparatus according to Claim 10, wherein all of said exhaust gases from the internal combustion engine and the fresh ambient air, prior to compression thereof by said compressor, are first cooled below a maximum intake temperature of the compressor and then, after cooling and compression, are injected into the mixing chamber of the cooling component set.Claim 12: The apparatus according to any one of Claims 1 to 1 1 , wherein the respective valve stem of the discharge valve is preloaded by a spring, and said discharge valve closes when the opening force exerted by the pressure within the combustion chamber drops below a spring force exerted by the spring.Claim 13: The apparatus according to any one of Claims 1 to 1 1 , wherein the respective valve stem of the discharge valve is actuated by a discharge valve actuator, and thedischarge valve remains open until the discharge valve actuator acts to close the discharge valve as soon as the exit check valve closes.Claim 14: The apparatus according to Claims 12 and 13 wherein, during the discharge stage, the exhaust valve opens immediately after the discharge valve closes.Claim 15: The apparatus according to any one of Claims 2, 3, 4, 10 and 1 1 , wherein the hot pulsating combustion gases and fresh ambient air are mixed with at least one other substance.Claim 16: The apparatus according to claim 15 wherein said at least one other substance comprises water mist.Claim 17: A flue gas generation apparatus for the generation of pulsating hot flue gases to be injected into an oil well in order to increase formation pressure and lower crude oil viscosity to facilitate mobility of said crude oil towards a wellbore of said oil well, said apparatus comprising a combustion component set operable in reciprocating fashion to generate hot pulsating combustion gases and exhaust gases, said combustion component set comprising at least one cylinder each having a respective piston and a respective cylinder head, and for each cylinder, at least one: (i) sparkplug, (ii) intake valve, (iii) exhaust valve, and (iv) discharge valve, of which the suction, exhaust and discharge valves of each cylinder are affixed to the respective cylinder head; wherein the piston is driven in reciprocating motion; a stroke of said reciprocating motion of the piston has a start that corresponds to a nearest position of the piston to the cylinder head, and an end that corresponds to a farthest position of the piston from the cylinder head; and the reciprocating motion of the piston within the cylinder includes: a suction stage characterized by movement of the piston away from the cylinder head with the discharge and exhaust valves held closed and the intake valve opento admit a pre-compressed combustible gases mixture, into a combustion chamber delimited between respective high pressure end of the piston and the cylinder head in a manner substantially filling said combustion chamber until closure of the intake valve at an end of said suction stage, and near the end of the stroke, upon which closure the pre-compressed combustible gases mixture is ignited by the at least one sparkplug; a discharge stage that follows the suction stage, near the end of the stroke, after complete combustion of the pre-compressed combustible gases mixture, and start with opening of the discharge valve by a sudden increase in pressure and expansion of combustion gases generated from said combustion, during which discharge state the intake and exhaust valves remain closed; an exhaust stage that follows the discharge stage, begins when the piston is moving toward the cylinder head and, once the discharge valve has closed, the exhaust valve opens, during which exhaust stage the intake valve remains closed, and the open exhaust valve allows remnant combustion gases to be evacuated.RECTIFIED SHEET (RULE 91.1 )

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