Thermal recovery device and process for multi-element thermal fluid of heavy oil well

Abstract

The invention belongs to the technical field of heavy oil recovery, and discloses a heavy oil well multi-element thermal fluid thermal recovery device and process which are high in thermal efficiency, low in environmental influence and high in flexibility. The device comprises a multi-element thermal fluid generating device, a fuel supply module, an oxidizing agent supply module, a heat-carrying medium supply module and an optional nitrogen supply module, the fuel supply module, the oxidizing agent supply module and the heat-carrying medium supply module are respectively connected with the multi-element thermal fluid generating device, and the multi-element thermal fluid generating device comprises a combustion chamber, a fuel inlet communicated with the fuel supply module and an oxidant inlet communicated with the oxidant supply module are formed in the inlet end of the combustion chamber, and an axial heat-carrying medium channel communicated with the heat-carrying medium supply module is formed in the periphery of the combustion chamber; the mixing chamber is simultaneously communicated with the outlet end of the combustion chamber and the outlet of the heat-carrying medium channel; the combustor outlet is communicated with the outlet of the mixing chamber and used for outputting the generated multi-element thermal fluid, and the component regulation and control module is used for regulating the component proportion of the fuel, the oxidizing agent and the heat-carrying medium.

Description

Technical Field

[0001] This invention relates to the field of heavy oil extraction technology, specifically to a multi-element thermal fluid extraction device and process for heavy oil wells. Background Technology

[0002] Heavy oil resources are widely distributed and abundant globally, but their extraction faces significant challenges due to their high content of gum and asphaltene, high viscosity, and poor fluidity. Currently, heavy oil extraction mainly relies on thermal recovery technologies, such as steam injection and steam drive. The basic principle of these technologies is to significantly reduce the viscosity of heavy oil and improve its fluidity by providing heat energy to the oil reservoir, thereby greatly increasing the recovery rate.

[0003] Although existing thermal recovery technologies have achieved results for a certain period of time, they face the following technical bottlenecks: First, energy efficiency and environmental pollution are prominent issues: current thermal recovery processes heavily rely on steam boilers (steam generators). These boilers typically use crude oil or heavy oil as fuel, and their thermal efficiency is generally low, only between 80% and 87%. This means that more than 13% of the fuel energy is wasted through flue gas and other means. More seriously, the combustion of fuel produces enormous amounts of greenhouse gases and pollutants. Statistics show that to inject 3,000 tons of steam into a thermal recovery well, approximately 180 tons of crude oil need to be burned, resulting in the direct emission of about 560 tons of carbon dioxide, 1.8 tons of sulfur dioxide, and 0.47 tons of nitrogen oxides into the atmosphere. This not only exacerbates the global greenhouse effect but also causes severe local air pollution, contradicting the concept of green mining.

[0004] Secondly, it consumes enormous amounts of water and has poor regional adaptability: steam injection and steam drive are typical "high water consumption" processes. Producing one ton of steam requires approximately 1.1 tons of high-quality fresh water. This might be manageable for water-rich regions, but in many heavy oil-rich areas around the world, such as moderately arid and semi-arid regions, water resources are extremely scarce, and the high cost of water resources severely restricts heavy oil development. Furthermore, the large amount of wastewater generated and treated also brings additional environmental burdens and costs.

[0005] Third, thermal efficiency and swept volume are limited: Simple steam thermal recovery relies primarily on the condensation heat transfer of steam. Over-coverage of steam during injection is prone to occur, leading to uneven vertical heating of the oil reservoir and hindering the effective utilization of lower-level crude oil. Simultaneously, heat loss from the wellbore and formation is significant, especially in deep reservoirs where effective heat utilization is even lower. Furthermore, with multiple rounds of extraction, formation pressure decreases, making it difficult to further expand the steam's swept range, thus limiting the ultimate recovery rate.

[0006] Fourth, offshore heavy oil extraction faces unique challenges: offshore platforms are characterized by limited space, limited capacity, extremely high operating costs, and a typical design life of only 20-30 years. Traditional steam boiler systems are bulky and heavy, making them difficult to install and deploy on platforms. Simultaneously, offshore oilfields require development plans that can achieve high-rate, high-recovery extraction within a short period to maximize the recovery of investment and resources over the platform's lifespan. Conventional cold recovery and traditional thermal recovery technologies cannot meet this demanding requirement. Based on the offshore platform's lifespan and an average final recovery rate of 20% for cold recovery, these oilfields will still have a large amount of remaining oil that cannot be extracted after the development period ends, resulting in permanent resource loss.

[0007] Fifth, the technology lacks flexibility and cannot adapt to the diverse needs of oil reservoirs: different reservoirs have different requirements for thermal fluids. For example, for extra-heavy oil, rapid and deep viscosity reduction is the primary task; while for heavy oil with some fluidity but insufficient formation energy, replenishing formation pressure is more critical. Traditional steam has a fixed composition (mainly water vapor), which cannot flexibly adjust its thermodynamic properties and chemical composition to adapt to these diverse needs, resulting in suboptimal extraction efficiency.

[0008] To address these issues, the industry has attempted to inject non-condensable gases (such as nitrogen and carbon dioxide) into steam to create a multi-component thermal fluid. However, existing technologies of this kind are often complex, with a fixed gas-steam mixing ratio and reliance on external gas supply, failing to fundamentally solve problems related to system efficiency, energy consumption, and water resource consumption. Summary of the Invention

[0009] In view of the above problems, this invention proposes a novel multi-element thermal fluid thermal recovery device and process for heavy oil wells that can take into account high thermal efficiency, low environmental impact and high flexibility, so as to be applicable to a variety of harsh conditions, thereby realizing economical, efficient and green heavy oil resource development.

[0010] According to one aspect of the present invention, a multi-component thermal recovery device for heavy oil wells is provided, comprising: a fuel supply module for storing and transporting fuel; an oxidant supply module for providing compressed air or oxygen-enriched air; a heat-carrying medium supply module for providing one of water, medium oil, and heat-carrying gas; a multi-component thermal fluid generator, the inlet of which is connected to the fuel supply module, the oxidant supply module, and the heat-carrying medium supply module respectively via pipelines, for mixing the high-temperature flue gas generated by the combustion of fuel and oxidant with the heat-carrying medium to generate a multi-component thermal fluid; and an optional nitrogen supply module for... Nitrogen gas is injected into the annulus between the injection string and the casing. The multi-component thermal fluid generator includes: a combustion chamber, the inlet end of which has a fuel inlet connected to a fuel supply module and an oxidant inlet connected to an oxidant supply module; an axial heat-carrying medium channel connected to a heat-carrying medium supply module is formed on the outer periphery of the combustion chamber; a mixing chamber connected to the outlet end of the combustion chamber and the outlet of the heat-carrying medium channel; a burner outlet connected to the outlet of the mixing chamber for outputting the generated multi-component thermal fluid; and a component control module for adjusting the component ratio of fuel, oxidant, and heat-carrying medium.

[0011] Furthermore, the composition control module includes: a fuel selection and switching unit, located between the fuel supply module and the fuel inlet, used to select and switch different types of fuel according to received control commands; an oxidant concentration adjustment unit, located between the oxidant supply module and the oxidant inlet, used to prepare and deliver an oxidant with a specific oxygen volume concentration; a heat-carrying medium proportion control unit, located between the heat-carrying medium supply module and the inlet of the heat-carrying medium channel, used to control the injection ratio and total flow rate of the heat-carrying medium; a real-time composition analysis module, located at the burner outlet, used to detect the material composition in the outflowing multi-component thermal fluid in real time; and a central control unit, whose signal input terminal is connected to the real-time composition analysis module, and whose signal output terminal is connected to the fuel selection and switching unit, the oxidant concentration adjustment unit, and the heat-carrying medium proportion control unit respectively. The central control unit pre-stores the target component models of the multi-component thermal fluid required for different reservoir types, and can generate and issue adjustment commands based on the difference between the online fluid composition and the target component model, so as to dynamically control the operating parameters of the fuel selection and switching unit, the oxidant concentration adjustment unit, and the heat-carrying medium proportion control unit, thereby realizing closed-loop control of the adjustment ratio of each component in the multi-component thermal fluid.

[0012] Furthermore, the multi-element heat fluid generating device also includes an atomizing module that can be selectively connected to the fuel supply module. The fuel is selected from at least one of crude oil, diesel, natural gas, and liquefied petroleum gas. When the fuel is crude oil and / or diesel, the atomizing module is turned on and connected to the fuel supply module; when the fuel is natural gas and / or liquefied petroleum gas, the atomizing module is turned off.

[0013] Furthermore, the heat-carrying medium passage is used only to supply medium oil, and the gas-oil ratio of the mixed gas generated by combustion in the combustion chamber to the medium oil is 50:1 to 400:1; or, the heat-carrying medium passage is used only to supply water, and the gas-water ratio of the mixed gas generated by combustion in the combustion chamber to the water is 100:1 to 300:1; or, the heat-carrying medium passage is used only to supply heat-carrying gas, and the gas-water ratio of the mixed gas generated by combustion in the combustion chamber to the heat-carrying gas is 400:1 to 800:1.

[0014] Furthermore, an oil storage pipe for containing circulating hot oil is formed between the outer periphery of the combustion chamber and the heat-carrying medium passage. The oil storage pipe is not connected to the mixing chamber.

[0015] Furthermore, the heavy oil well multi-electro-thermal fluid thermal recovery device also includes: a reagent injection module, the outlet of which is connected to the outlet of the multi-electro-thermal fluid generator, for adding corrosion inhibitors and / or viscosity reducers to the multi-electro-thermal fluid or casing.

[0016] Furthermore, the multi-electro-thermal fluid thermal recovery device for heavy oil wells also includes: a downhole auxiliary heat generation system, which includes an electric heater or a downhole chemical thermal reactor, and is installed at the end of the injection string or in the oil layer.

[0017] According to another aspect of the present invention, a multi-component thermal fluid recovery process for heavy oil wells is proposed, employing the aforementioned multi-component thermal fluid recovery device for heavy oil wells, comprising the following steps: Step 1: Fuel and oxidant are injected into the combustion chamber respectively, and ignited to generate high-temperature flue gas; Step 2: One of water, medium oil, and heat-carrying gas is injected into the heat-carrying medium channel to exchange heat with the high-temperature flue gas, and mixed in the mixing chamber to generate a multi-component thermal fluid with a predetermined temperature and composition, wherein the composition ratio of carbon dioxide, nitrogen, steam, and high-temperature medium oil in the multi-component thermal fluid is controlled by adjusting the composition ratio of fuel, oxidant, and heat-carrying medium through a composition control module; Step 3: The multi-component thermal fluid is injected into the target oil layer through an injection tubing; Step 4: Nitrogen is continuously injected through the annulus between the injection tubing and the casing while injecting the multi-component thermal fluid.

[0018] Furthermore, the injection temperature of the multi-element heat fluid is 120℃ to 350℃, the injection pressure is not less than 35MPa, and the injection rate is 50t / d to 350t / d.

[0019] Furthermore, while injecting the multi-component thermal fluid, the downhole auxiliary heating system is activated to provide auxiliary heating to the vicinity of the injection string or deep oil layer; and / or the chemical injection module is activated to add corrosion inhibitors and / or viscosity reducers to the multi-component thermal fluid or casing.

[0020] Compared with existing thermal recovery technologies such as steam injection, this invention, by modularizing and integrating the multi-element thermal fluid generator and innovatively introducing a component intelligent control module and annular nitrogen injection technology, completely overcomes the inherent defects of traditional technologies, such as low thermal efficiency, huge energy and water consumption, serious CO2 emissions, bulky equipment, and limited reservoir adaptability. It enables high thermal efficiency, low energy consumption, low water consumption, and near-zero pollution extraction operations within a limited platform space. Furthermore, it can tailor multi-element thermal fluid formulations according to reservoir characteristics, thereby significantly improving oil production rate and ultimate recovery rate, providing a revolutionary solution for the economical and green development of heavy oil resources. Attached Figure Description

[0021] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the embodiments of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings: Figure 1 A schematic diagram of the structure of a multi-element thermal fluid recovery device for heavy oil wells according to an embodiment of the present invention is shown; Figure 2 It shows Figure 1 A schematic diagram of the first embodiment of the multi-element thermal fluid generator shown; Figure 3 It shows Figure 1 A schematic diagram of the second embodiment of the multi-element thermal fluid generator shown; Figure 4 A flowchart of a multi-element thermal fluid recovery process for heavy oil wells according to an embodiment of the present invention is shown; Figure 5 A schematic diagram of a multi-element thermal fluid recovery process for heavy oil wells according to an embodiment of the present invention is shown for use in a multi-well group. Detailed Implementation

[0022] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0023] Figure 1 The structure of a multi-element thermal fluid recovery device 100 for heavy oil wells according to an embodiment of the present invention is shown. Figure 1As shown, the heavy oil well multi-element thermal fluid recovery device 100 may include: a fuel supply module 1 for storing and transporting fuel; an oxidant supply module 2 for providing compressed air or oxygen-enriched air; a heat-carrying medium supply module 3 for providing one of water, medium oil, and heat-carrying gas, which may be deoxygenated air, hydrogen, nitrogen, etc.; a multi-element thermal fluid generator 4, whose inlet end is connected to the fuel supply module 1, oxidant supply module 2, and heat-carrying medium supply module 3 respectively via pipelines, for mixing the high-temperature flue gas generated by the combustion of fuel and oxidant with the heat-carrying medium to generate a multi-element thermal fluid; and an optional nitrogen supply module 5 for injecting nitrogen into the annulus between the injection string and the casing. Among these, combined with... Figure 2 and Figure 3 As shown, the multi-component thermal fluid generator 4 may include: a combustion chamber 41, with a fuel inlet 42 connected to the fuel supply module 1 and an oxidant inlet 43 connected to the oxidant supply module 2 at the inlet end of the combustion chamber 41; a heat-carrying medium channel 44 axially connected to the heat-carrying medium supply module 3 formed on the outer periphery of the combustion chamber 41; a mixing chamber 45 connected to both the outlet end of the combustion chamber 41 and the outlet of the heat-carrying medium channel 44; a burner outlet 46 connected to the outlet of the mixing chamber 45 for outputting the generated multi-component thermal fluid; and a component control module (not shown in the figure) for adjusting the component ratio of fuel, oxidant, and heat-carrying medium.

[0024] When the heavy oil well multi-element thermal fluid thermal recovery device 100 of this embodiment of the invention is working, it combines with Figures 1 to 3 As shown, fuel and oxidant are respectively transported to the combustion chamber 41 of the multi-component thermal fluid generator 4 through fuel inlet 42 and oxidant inlet 43 and ignited to generate high-temperature flue gas. Simultaneously, the heat-carrying medium is pumped into the heat-carrying medium channel 44 surrounding the combustion chamber through heat-carrying medium inlet 47. The preheated heat-carrying medium enters the mixing chamber 45 through heat-carrying medium outlet 48 and mixes violently with the high-temperature flue gas in the mixing chamber 45, completing the final heat exchange and generating a multi-component thermal fluid containing steam, nitrogen, carbon dioxide, and possibly high-temperature medium oil. This thermal fluid enters the injection string 102 through burner outlet 46 and is transported to the downhole oil layer. Throughout the injection process, the nitrogen supply module 5 can independently and continuously inject nitrogen into the annulus between the injection string 102 and the casing 101 under the action of the nitrogen booster 51. The nitrogen is used to form a heat insulation layer to reduce heat loss in the injection string 102 and to supplement and maintain the oil layer pressure. This nitrogen merges with the multi-component thermal fluid at the bottom of the well, working together to benefit the oil layer.

[0025] The heavy oil well multi-component thermal recovery device 100 of this invention, by setting up a multi-component thermal fluid generator 4, has a built-in component control module that can adjust the component ratio of fuel, oxidant and heat-carrying medium, so that fuel, oxidant and heat-carrying medium can be adaptively adjusted according to actual needs. For example, by selecting fuels with different carbon-to-hydrogen ratios (such as low-carbon natural gas or high-carbon crude oil), the reference ratio of CO2 and N2 in the combustion products can be directly controlled. When strong viscosity reduction is required, high-carbon fuel can be selected to increase CO2 generation. When gas expansion is required, low-carbon fuel can be selected to generate more N2. By adjusting the oxygen concentration in the oxidant (air or oxygen-enriched air), the combustion process and products can be precisely controlled. For example, increasing the oxygen concentration not only makes combustion more complete and the flame temperature higher, but also significantly improves the purity and partial pressure of CO2 in the flue gas, thereby producing a high-concentration CO2 thermal fluid when needed. By controlling the injection ratio and total amount of water and medium oil, the gas-phase or liquid-phase composition and thermophysical properties of the final thermal fluid can be flexibly determined. This not only enables switching from high water consumption to low water consumption or even waterless conditions, adapting to water-scarce areas, but also optimizes the heat-carrying capacity and sweep efficiency of the fluid by adjusting the gas-water ratio or gas-oil ratio. In addition, traditional steam boilers can only output steam with a fixed composition, while the multi-component thermal fluid recovery device 100 for heavy oil wells in this embodiment of the invention can output a multi-component thermal fluid with dynamically programmable chemical composition and thermodynamic properties by precisely proportioning the above three basic raw materials. This allows an oil well to obtain a customized optimal extraction fluid at different stages of extraction or in reservoirs with different characteristics.

[0026] The component adjustability of the multi-component thermal fluid recovery device 100 for heavy oil wells in this invention is the fundamental prerequisite for achieving all subsequent process effects, such as efficient viscosity reduction (by increasing CO2 content), effective pressurization (by increasing N2 content), and significant water saving (by reducing water content or using medium oil). The modularity and integration of the entire multi-component thermal fluid recovery device 100 make it suitable for space-constrained offshore platforms. The component control module enables flexible adjustment of the multi-component thermal fluid components to meet the personalized needs of different reservoirs. Annular nitrogen injection effectively reduces wellbore heat loss, protects the casing, and replenishes formation energy. This multi-component thermal fluid recovery device 100 achieves a balance of high thermal efficiency, low environmental impact, and strong reservoir adaptability, providing a practical technical equipment for heavy oil extraction.

[0027] In a preferred embodiment, the combustion chamber 41 can be designed as a high-temperature and high-pressure resistant cylinder, and the fuel inlet 42 and oxidant inlet 43 can be designed with special structures (such as cyclones) to promote mixing. The heat-carrying medium channel 44 can be jacketed around the combustion chamber 41, which not only preheats the heat-carrying medium but also effectively cools and protects the walls of the combustion chamber 41. A spiral channel can be formed inside the heat-carrying medium channel 44 to slow down the flow velocity of the heat-carrying medium, thereby enabling sufficient heat exchange between the heat-carrying medium and the heat generated by the high-temperature flue gas. The mixing chamber 45 can be equipped with baffles, static mixers, or atomizing nozzles to ensure vigorous and thorough mixing and heat exchange between the high-temperature flue gas and the heat-carrying medium.

[0028] According to a preferred embodiment of the present invention, the component control module may include: a fuel selection and switching unit, disposed between the fuel supply module 1 and the fuel inlet 42, for selecting and switching different types of fuel according to received control commands; an oxidant concentration adjustment unit, disposed between the oxidant supply module 2 and the oxidant inlet 43, for preparing and delivering an oxidant with a specific oxygen volume concentration; a heat-carrying medium proportion control unit, disposed between the heat-carrying medium supply module 3 and the inlet of the heat-carrying medium channel, for controlling the injection ratio and total flow rate of the heat-carrying medium; and a real-time component analysis module, disposed at the burner outlet 46, for... The system monitors the composition of the outflowing multi-component thermal fluid in real time. It also includes a central control unit, whose signal input is connected to the real-time component analysis module, and whose signal output is connected to the fuel selection and switching unit, the oxidant concentration adjustment unit, and the heat-carrying medium proportion control unit. The central control unit has pre-stored target component models of the multi-component thermal fluid required for different reservoir types. It can generate and issue adjustment commands based on the difference between the online fluid composition and the target component model to dynamically control the operating parameters of the fuel selection and switching unit, the oxidant concentration adjustment unit, and the heat-carrying medium proportion control unit, thereby achieving closed-loop control of the adjustment ratio of each component in the multi-component thermal fluid.

[0029] In this embodiment, the component control module serves as the intelligent core, with its hardware integrated into each pipeline and its software algorithm embedded in the central control unit. By setting up a complete closed-loop control system that includes fuel selection, oxidant concentration adjustment, heat-carrying medium ratio control, real-time component analysis, and the central control unit, a precise, automated, and adaptive control method for the components of multi-element thermal fluids is achieved, ensuring the stable and optimal quality of the produced fluid and maximizing the thermal recovery effect.

[0030] Preferably, the fuel selection and switching unit can be composed of multiple sets of parallel pipelines, high-precision control valves, and flow meters to achieve seamless switching between different fuel sources. The oxidant concentration adjustment unit can integrate a pressure swing adsorption (PSA) oxygen generator or a membrane separation oxygen generator and be coordinated with an air compressor to achieve continuous adjustment of oxygen concentration. The heat-carrying medium proportional control unit can precisely control the mixing ratio or individual flow rate of water and medium oil through a metering pump and proportional valve. The real-time component analysis module can use an online gas chromatograph or an infrared gas analyzer. The central control unit (e.g., a PLC or industrial computer) has a built-in PID control algorithm and reservoir component model database. By receiving feedback signals from the analysis module, it compares and calculates with target values ​​and outputs instructions to drive the actions of each execution unit, forming a high-precision closed-loop control circuit.

[0031] In such Figure 2 and Figure 3 In the preferred embodiment shown, the multi-element thermal fluid generator 4 may further include an atomizing module 40 selectively connected to the fuel supply module 1. The fuel can be selected from at least one of crude oil, diesel, natural gas, and liquefied petroleum gas. When the fuel is crude oil and / or diesel, the atomizing module is turned on and connected to the fuel supply module; when the fuel is natural gas and / or liquefied petroleum gas, the atomizing module is turned off. By setting a selectable atomizing module 40 and limiting the fuel type, the multi-element thermal fluid generator 4 can be compatible with multiple liquid and gaseous fuels, improving the adaptability of the equipment and the flexibility of fuel sources. At the same time, atomization ensures the complete combustion of liquid fuels, improving combustion efficiency and system stability.

[0032] Preferably, the atomization module 40 may include a high-pressure pump, a preheater, and a mechanical atomizing nozzle or a medium atomizing nozzle. Its function is to break the liquid fuel into micron-sized droplets, greatly increasing its contact area with the oxidant, thereby ensuring rapid and complete combustion in the combustion chamber, avoiding carbon buildup and black smoke, and ensuring combustion stability and efficiency.

[0033] According to the present invention, the heat-carrying medium channel 44 can be used to provide one of water, medium oil, and heat-carrying gas. In such cases... Figure 2 In the preferred embodiment shown, the heat-carrying medium channel 44 can be used only to supply medium oil, and the gas-oil ratio of the mixed gas generated by combustion in the combustion chamber 41 to the medium oil is preferably 50:1 to 400:1. This embodiment achieves waterless operation, avoids the use of water resources, and provides a feasible technical solution for heavy oil extraction in arid regions or sea areas with scarce freshwater resources.

[0034] In such Figure 2In the preferred embodiment shown, the heat-carrying medium channel 44 can be used to provide only a small amount of water, and the gas-water ratio of the mixed gas generated by combustion in the combustion chamber 41 is preferably 100:1 to 300:1. This embodiment achieves operation under low-water conditions, greatly saving water resources, providing a feasible technical solution for heavy oil extraction in arid regions or sea areas with scarce freshwater resources, and at the same time broadening the application scope of the process.

[0035] To further optimize thermal management, in situations such as Figure 3 In the preferred embodiment shown, an independent oil storage pipe 49 can be added between the outer periphery of the combustion chamber and the heat-carrying medium channel 44. This oil storage pipe 49 is filled with high-temperature hot oil through the oil storage pipe inlet 471, forming a circulation loop. This loop is isolated from the process medium flowing to the mixing chamber 45. Its main function is to absorb excess heat from the walls of the combustion chamber 41 and transfer it to the water in the heat-carrying medium channel 44. This ensures that the water maintains a uniform temperature throughout the entire axial direction as it flows through the very long heat-carrying medium channel 44, thereby enabling more thorough mixing with the high-temperature flue gas generated in the combustion chamber 41. Simultaneously, the high-temperature hot oil in the oil storage pipe 49 also helps to equalize and protect the combustion chamber 41, preventing heat waste.

[0036] In another preferred embodiment, the heat-carrying medium channel is used only to provide the heat-carrying gas, and the gas-to-water ratio of the mixed gas generated by combustion in the combustion chamber to the heat-carrying gas is 400:1 to 800:1. This embodiment can solve the problem of insufficient freshwater / purified water resources by using gas to carry heat, thereby achieving the effects of gas energy enhancement and viscosity reduction.

[0037] In such Figure 1 In the preferred embodiment shown, the heavy oil well multi-element thermal fluid recovery device 100 may further include a reagent injection module 6, the outlet of which is connected to the outlet of the multi-element thermal fluid generator 4, for adding corrosion inhibitors and / or viscosity reducers to the multi-element thermal fluid or casing 101. By adding the reagent injection module 6, chemical agents such as corrosion inhibitors or viscosity reducers can be added to the system as needed, thereby effectively alleviating the corrosion problem of the wellbore and equipment, and further reducing the viscosity of heavy oil, thus playing a role in assisting to improve the recovery rate and protect the equipment.

[0038] Preferably, the agent injection module 6 may include an agent tank, a small injection pump and an injection head, which can directly inject corrosion inhibitors (such as film-forming amines) into the multi-element hot fluid outlet pipeline, or inject corrosion inhibitors into the annulus to protect the injection string 102 and the sleeve 101.

[0039] In such Figure 1In the preferred embodiment shown, the multi-element thermal fluid recovery device 100 for heavy oil wells may further include a downhole auxiliary heat generation system 7. The downhole auxiliary heat generation system 7 may include an electric heater or a downhole chemical thermal reactor, and is located at the end of the injection string 102 or in the oil layer. This setup enables targeted and enhanced heating near the injection string 102 or in the deep oil layer, and is suitable for extra-heavy oil wells or deep wells with high wellbore heat loss. It effectively expands the heating radius and overcomes the limitations of conventional thermal fluid heating ranges.

[0040] Preferably, in the downhole auxiliary heat generation system, the electric heater can be a sheathed resistance heater, which can be lowered by cable and suspended at the end of the injection string 102, and powered by the electric heating control system 72. The electric heater can also be set in the oil layer 8. The downhole chemical heat generation reactor can inject heat-generating agents (such as a mixture of ammonium nitrate and catalyst) into a specific layer through the downhole reaction heat generation agent supply system 71, and use chemical reaction to locally release heat in the deep oil layer as an effective supplement to the main heat fluid.

[0041] Figure 4 A flowchart of a multi-component thermal recovery process for heavy oil wells according to an embodiment of the present invention is shown. This process, employing the aforementioned multi-component thermal recovery device, may include the following steps: Step 1 (S1): Fuel and oxidant are injected into combustion chamber 41, ignited, and combusted to generate high-temperature flue gas; Step 2 (S2): One of water, medium oil, and heat-carrying gas is injected into heat-carrying medium channel 44 for heat exchange with the high-temperature flue gas, and mixed in mixing chamber 45 to generate a multi-component thermal fluid with a predetermined temperature and composition. The composition ratio of fuel, oxidant, and heat-carrying medium is adjusted by a component control module to control the proportions of carbon dioxide, nitrogen, steam, and high-temperature medium oil in the multi-component thermal fluid; Step 3 (S3): The multi-component thermal fluid is injected into the target oil layer through injection string 102; Step 4 (S4): Simultaneously with the injection of the multi-component thermal fluid, nitrogen is continuously injected through the annulus between injection string 102 and casing 101.

[0042] In the implementation of the multi-component thermal recovery process for heavy oil wells according to this invention, fuel and oxidant are precisely fed into the combustion chamber 41 of the generator in a specific ratio. After ignition, they undergo intense combustion, generating high-temperature flue gas (>1000℃) with CO2, N2, and water vapor as its main components. Simultaneously, the heat-carrying medium (water or medium oil) is preheated by absorbing heat transferred from the wall as it flows through the annular channel outside the combustion chamber 41. Subsequently, the high-temperature flue gas and the preheated heat-carrying medium undergo direct contact and thorough heat exchange in the mixing chamber, ultimately generating a multi-component thermal fluid with adjustable temperature range and component ratios. A real-time component analysis module monitors the outlet multi-component thermal fluid online. The central control unit compares the detection data with a preset target model and dynamically adjusts parameters such as fuel type, oxidant concentration, and medium ratio to achieve closed-loop control, ensuring that the multi-component thermal fluid composition is always optimal. The generated multi-component thermal fluid is injected into the oil reservoir through injection tubing 102. The large amount of heat it carries directly heats the heavy oil, significantly reducing its viscosity. CO2 dissolves in the crude oil, further reducing viscosity and expanding the crude oil. N2, as a non-condensable gas, expands the heating sweep volume and provides driving energy. Simultaneously, nitrogen is continuously injected into the annulus, forming a heat insulation layer in the wellbore to reduce heat loss during the upward movement of the thermal fluid. After entering the oil reservoir at the bottom of the well, it works synergistically with the gas components in the multi-component thermal fluid to form a gas cap at the top of the reservoir, enhancing driving capability. After injection, the well is shut in for several days to allow the heat and gas to fully diffuse and interact. The well is then opened, and oil production is achieved through formation energy self-flow or by running pumps. When production declines, this injection cycle can be repeated, or a continuous injection mode such as multi-component thermal fluid displacement can be adopted.

[0043] Preferably, the component ratio adjustment in step two (S2) is a dynamic process. For example, to enhance viscosity reduction, the system can be instructed to switch to diesel fuel and increase the oxygen concentration; to save water, the system can be instructed to reduce the water flow rate and increase the gas-water ratio. More preferably, the annular nitrogen injection in step four (S4) is a continuous process, and its injection flow rate and pressure need to be optimized according to the wellbore temperature field and formation pressure to ensure thermal insulation and effectively replenish formation energy.

[0044] In a preferred embodiment, the injection temperature of the multi-component thermal fluid is between 120°C and 350°C, the injection pressure is not less than 35 MPa, and the injection rate is between 50 t / d and 350 t / d. This setting is crucial for ensuring the effectiveness of the process. Too low a temperature results in insufficient viscosity reduction, and insufficient pressure prevents overcoming formation pressure for effective injection. This setting ensures that the multi-component thermal fluid has sufficient energy to penetrate the wellbore and effectively heat the oil layer, while also guaranteeing the safety and efficiency of the injection process, providing a critical operating window for economical and efficient extraction.

[0045] In a preferred embodiment, while injecting the multi-component thermal fluid, the downhole auxiliary heating system 7 can be activated to provide auxiliary heating to the vicinity of the injection string 102 or the deep reservoir; and / or the chemical injection module 6 can be activated to add corrosion inhibitors and / or viscosity reducers to the multi-component thermal fluid or casing 101. This setup achieves synergistic effects between the main process and auxiliary measures, and can further enhance the production effect through combined technologies under complex or harsh reservoir conditions, thereby improving the adaptability and effectiveness of the entire process system.

[0046] The multi-element thermal fluid recovery technology for heavy oil wells in this invention can be applied to single-well huff and puff (injection-shutdown-production cycle) or multi-well group displacement (one injection, multiple production) or multi-element thermal fluid assisted gravity drive, exhibiting high flexibility. Specifically, when performing multi-element thermal fluid huff and puff, after injecting a predetermined amount of multi-element thermal fluid, the well can be shut in and shut down for 2-5 days before being opened for oil production; when the daily oil production is lower than the economic limit, the cycle of injection, shut-in, and production can be repeated.

[0047] The following are specific embodiments of the heavy oil well multi-electro-thermal fluid thermal recovery process according to the present invention, and comparative examples using the conventional steam huff and puff process: Comparative Example: A conventional steam injection process was used for production in a directional well of extra-heavy oil (3550m depth, 30m vertical oil layer thickness, 11000mPa·s viscosity at 50℃). This process employed a steam boiler, burning diesel fuel to generate saturated steam at 300℃, which was then injected into the oil layer through insulated tubing. To achieve a heat input comparable to the subsequent examples, approximately 7500 tons of steam needed to be injected cumulatively. The entire process consumed approximately 450 tons of diesel fuel and a staggering 8250 tons of clean water. After injection and well shut-in, production resumed. However, due to the lack of gas-assisted drive and viscosity-reducing effects from the injected pure steam, production declined rapidly, with the well's average daily oil production reaching only 35 tons.

[0048] Example 1: Based on a directional well for extra-heavy oil with the same specifications as the comparative example, the multi-element thermal fluid huff and puff process of this invention is adopted. In this example, the high-temperature flue gas generated by the combustion of diesel and air is efficiently exchanged with softened water through the multi-element thermal fluid generator 4. The oxidant is air with an oxygen concentration of 20%, the air-fuel ratio (mass ratio) is 13.585, the heat-carrying medium is water, the designed gas-water ratio (volume ratio) is 169:1, and the temperature of the multi-element thermal fluid is 300°C.

[0049] First, diesel fuel is pumped from the fuel tank to the combustion chamber 41 of the multi-element thermal fluid generator 4 at a rate of 80 kg / h via an oil injection pump. Pressurized air (pressure less than 25 MPa) is pumped into the combustion chamber 41 of the multi-element thermal fluid generator 4 at a rate of 1100 kg / h via an air compressor and turbocharger. After ignition by the igniter in the multi-element thermal fluid generator 4, the diesel fuel burns, releasing a large amount of heat and generating a high-temperature mixture. Simultaneously, water treated by the water treatment system is pumped into the heat-carrying medium channel 44 at a rate of 6 t / h via a water injection pump. (The water treatment system separates calcium, magnesium, sodium, and other ions in the incoming water based on the principle of reverse osmosis membrane separation, reducing conductivity and softening the water to meet usage requirements.) The large amount of heat released by the diesel fuel combustion and its heat exchange with water generate a multi-element thermal fluid. The composition control module monitors the outlet fluid composition in real time, measuring that the generated multi-element thermal fluid contains 30% N2, 8% CO2, and 62% steam. The composition control module compares the measured proportions of each component in the multi-component thermofluid with the preset target composition model of the multi-component thermofluid required for this reservoir type. By fine-tuning the air-fuel ratio and water flow rate, it ensures composition stability and achieves an air-water ratio of 169:1.

[0050] Then, the generated multi-component thermal fluid at 300℃ and 10MPa is transported to the wellhead via surface pipeline, and then to the bottom of the well via ordinary tubing or insulated tubing. At the bottom of the well, the multi-component thermal fluid is injected into the oil layer through perforated holes at an injection rate of 183 m / s. 3 / d, with a total injection volume of 5170 t. Simultaneously, nitrogen gas is continuously injected into the annulus at an injection rate of 500 Nm. 3 / h.

[0051] After injection is completed, shut down the multi-element thermal fluid generator 4, stop water injection and nitrogen injection, shut in the well for 4 days, open the well to release the oil flow, and after 6 days of self-flow, run in the electric submersible pump for production. When the production is less than 30 cubic meters, restart the above cycle of injection, shut in the well and oil production. This process can be repeated for more than 10 cycles.

[0052] In Example 1, through precise control of the component regulation module, the proportions of nitrogen, carbon dioxide, and water vapor in the produced fluid were stabilized within the optimal range. During this cycle, a total of 5170 tons of multi-component thermal fluid were injected, consuming approximately 300 tons of diesel fuel and 5600 tons of fresh water. Compared to traditional steam injection, while saving 33.3% of fuel and 32.1% of fresh water, the well achieved an average daily oil production of 61 tons after commissioning, representing a significant 74.3% increase in production capacity. This fully demonstrates the substantial advantages of multi-component thermal fluid in improving thermal energy utilization and overall oil displacement efficiency.

[0053] Example 2: The difference from Example 1 is that, while the multi-component thermal fluid generator 4 is burning, the chemical thermal reaction feedstock (such as a mixture of ammonium nitrate and catalyst) is transported to the downhole auxiliary thermal system 7 through the downhole reaction thermal agent supply system. The heat from the multi-component thermal fluid can heat the catalyst and the chemical thermal reaction feedstock, releasing more heat. After injection is completed, the multi-component thermal fluid generator 4 is shut off, the injection medium oil and chemical thermal reaction feedstock are stopped, the well is shut in for 3 days, the well is opened and oil is produced by venting, and after 6 days of self-flowing, an electric submersible pump is installed for production. When the production is less than 30 cubic meters, the above-mentioned injection, shut-in, and oil production cycle is restarted, and the huff and puff cycle can reach 8 cycles.

[0054] Following the operating method of Example 2, downhole chemical reaction-assisted multi-element hot fluid huff and puff was used to produce oil in the heavy oil well. Peak daily oil production reached 75 tons. Compared to traditional steam huff and puff, peak production increased by approximately 114% while saving 33.3% of fuel and 32.1% of clean water. The cumulative oil production over the entire huff and puff cycle reached 20,000 tons. This result demonstrates that this enhanced process has excellent adaptability and production-increasing effect for the extraction of extra-heavy oil.

[0055] Example 3: The difference from Example 1 is that, while the multi-element thermal fluid generator 4 is burning, the electric heater is turned on and set to a power of 200kW. The electric heater can reheat the multi-element thermal fluid, increasing the injection formation temperature. After injection is completed, the generator is turned off, water injection is stopped, the well is shut in for 3 days, the well is opened and oil is produced by venting. After 6 days of self-flowing, an electric submersible pump is installed for production. When the production is less than 30 cubic meters, the above-mentioned injection, shut-in, and oil production cycle is restarted. The churn cycle can reach 8 cycles.

[0056] Following the operating method of Example 3, downhole chemical reaction-assisted multi-element hot fluid huff and puff was used to produce oil in the heavy oil well. Peak daily oil production reached 69 tons. Compared to traditional steam huff and puff, peak production increased by approximately 99% while saving 33.3% of fuel and 32.1% of clean water. The cumulative oil production over the entire huff and puff cycle reached 15,000 tons. This result demonstrates that this enhanced process has excellent adaptability and production-increasing effect for the extraction of extra-heavy oil.

[0057] Example 4: This invention can also be applied to well group displacement modes. In cases such as... Figure 5In the simple well network of one injection and two production wells shown, the well spacing between injection well 10 and the first production well 20 and the second production well 30 is 170m. The multi-element thermal fluid generated during the above process is injected through injection well 10 using a slug injection method. The process involves injecting the multi-element thermal fluid for 3 months, followed by water injection for 1 month, and then injecting the multi-element thermal fluid again for 2 months. Simultaneously, the first production well 20 and the second production well 30 continue normal production. The production cycle is one year, and the production-injection ratio is controlled at 1.4. After applying this displacement technology, the average daily oil production of the two production wells stabilized at 50 tons, representing a 2% to 9% increase in cumulative oil production compared to the traditional steam displacement technology. This result verifies that the present invention not only performs excellently in single-well injection and production but also effectively improves recovery rates in large-scale displacement production. Furthermore, thanks to its high gas-water ratio, it achieves water conservation and energy saving throughout the entire oilfield development cycle.

[0058] As can be seen from the comparison of the above comparative examples and embodiments, the multi-electro-thermal fluid thermal recovery technology for heavy oil wells in the embodiments of the present invention can significantly improve the production capacity and final recovery rate of heavy oil extraction while significantly saving water resources and fuel under different application modes and enhancement measures, resulting in outstanding comprehensive technical and economic benefits.

[0059] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the claims and specification of the present invention. In particular, as long as there is no structural conflict, the various technical features mentioned in the embodiments can be combined in any way. The present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A multi-element thermal fluid recovery device for heavy oil wells, characterized in that, include: Fuel supply module for storing and transporting fuel; Oxidant supply module, used to provide compressed air or oxygen-enriched air; A heat-carrying medium supply module is used to supply one of water, medium oil, and heat-carrying gas; The multi-component heat fluid generator has its inlet end connected to the fuel supply module, the oxidant supply module and the heat-carrying medium supply module via pipelines, respectively, for mixing the high-temperature flue gas generated by the combustion of fuel and oxidant with the heat-carrying medium to generate a multi-component heat fluid. And an optional nitrogen supply module for injecting nitrogen into the annulus between the injection string and the casing. The multi-component thermal fluid generating device includes: a combustion chamber, the inlet end of which has a fuel inlet connected to the fuel supply module and an oxidant inlet connected to the oxidant supply module; an axial heat-carrying medium channel connected to the heat-carrying medium supply module formed on the outer periphery of the combustion chamber; a mixing chamber connected to the outlet end of the combustion chamber and the outlet of the heat-carrying medium channel; a burner outlet connected to the outlet of the mixing chamber for outputting the generated multi-component thermal fluid; and a component control module for adjusting the component ratio of the fuel, oxidant, and heat-carrying medium.

2. The heavy oil well multi-element thermal fluid recovery device according to claim 1, characterized in that, The component regulation module includes: A fuel selection and switching unit is disposed between the fuel supply module and the fuel inlet, and is used to select and switch different types of fuel according to the received control commands; An oxidant concentration regulating unit is disposed between the oxidant supply module and the oxidant inlet, and is used to prepare and deliver an oxidant with a specific oxygen volume concentration; A heat-carrying medium proportional control unit is disposed between the heat-carrying medium supply module and the inlet of the heat-carrying medium channel, and is used to control the injection ratio and total flow rate of the heat-carrying medium. A real-time component analysis module, installed at the burner outlet, is used to detect the material composition of the outflowing multi-component thermal fluid in real time; and The central control unit has its signal input terminal connected to the real-time component analysis module, and its signal output terminal connected to the fuel selection and switching unit, the oxidant concentration adjustment unit, and the heat-carrying medium proportion control unit, respectively. The central control unit has pre-stored target component models of multi-component thermal fluids required for different reservoir types, and can generate and issue adjustment commands based on the difference between the online fluid components and the target component models, so as to dynamically control the operating parameters of the fuel selection and switching unit, the oxidant concentration adjustment unit, and the heat-carrying medium proportion control unit, thereby realizing closed-loop control of the adjustment ratio of each component in the multi-component thermal fluid.

3. The heavy oil well multi-element thermal fluid recovery device according to claim 1 or 2, characterized in that, The multi-element hot fluid generator further includes an atomizing module that can be selectively connected to the fuel supply module. The fuel is selected from at least one of crude oil, diesel, natural gas, and liquefied petroleum gas. When the fuel is crude oil and / or diesel, the atomizing module is turned on and connected to the fuel supply module; when the fuel is natural gas and / or liquefied petroleum gas, the atomizing module is turned off.

4. The heavy oil well multi-element thermal fluid recovery device according to claim 1 or 2, characterized in that, The heat-carrying medium channel is used only to provide medium oil, and the gas-oil ratio of the mixed gas generated by combustion in the combustion chamber to the medium oil is 50:1 to 400:1; or, the heat-carrying medium channel is used only to provide water, and the gas-water ratio of the mixed gas generated by combustion in the combustion chamber to the water is 100:1 to 300:1; or, the heat-carrying medium channel is used only to provide heat-carrying gas, and the gas-water ratio of the mixed gas generated by combustion in the combustion chamber to the heat-carrying gas is 400:1 to 800:

1.

5. The heavy oil well multi-element thermal fluid recovery device according to claim 4, characterized in that, An oil storage pipe for containing circulating hot oil is also formed between the outer periphery of the combustion chamber and the heat-carrying medium channel, and the oil storage pipe is not connected to the mixing chamber.

6. The heavy oil well multi-element thermal fluid recovery device according to claim 1 or 2, characterized in that, The heavy oil well multi-element thermal fluid thermal recovery device further includes: a reagent injection module, the outlet of which is connected to the outlet of the multi-element thermal fluid generator, for adding corrosion inhibitors and / or viscosity reducers to the multi-element thermal fluid or casing.

7. The heavy oil well multi-element thermal fluid recovery device according to claim 1 or 2, characterized in that, The heavy oil well multi-electro-thermal fluid thermal recovery device also includes: a downhole auxiliary heat generation system, which includes an electric heater or a downhole chemical heat generation reactor, and is installed at the end of the injection string or in the oil layer.

8. A multi-element thermal fluid recovery process for heavy oil wells, employing the multi-element thermal fluid recovery device for heavy oil wells according to any one of claims 1-7, characterized in that, Includes the following steps: Step 1: Inject fuel and oxidizer into the combustion chamber respectively, and ignite them to produce high-temperature flue gas; Step 2: Inject one of water, medium oil, and heat-carrying gas into the heat-carrying medium channel to exchange heat with the high-temperature flue gas, and mix them in the mixing chamber to generate a multi-component thermal fluid with a predetermined temperature and composition. The composition ratio of carbon dioxide, nitrogen, steam, and high-temperature medium oil in the multi-component thermal fluid is controlled by adjusting the composition ratio of the fuel, oxidant, and heat-carrying medium through the composition control module. Step 3: Inject the multi-element thermal fluid into the target oil layer through an injection string; Step 4: While injecting the multi-element thermofluid, nitrogen gas is continuously injected through the annulus between the injection string and the casing.

9. The multi-element thermal fluid recovery technology for heavy oil wells according to claim 8, characterized in that, The injection temperature of the multi-element thermal fluid is 120℃ to 350℃, the injection pressure is not less than 35MPa, and the injection rate is 50t / d to 350t / d.

10. The multi-element thermal fluid recovery technology for heavy oil wells according to claim 8, characterized in that, While injecting the multi-component thermal fluid, the downhole auxiliary heating system is activated to provide auxiliary heating to the vicinity of the injection tubing or deep oil layer; and / or the chemical injection module is activated to add corrosion inhibitors and / or viscosity reducers to the multi-component thermal fluid or casing.

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