A method for realizing efficient in-situ hydrogen production in a heavy oil reservoir by using a horizontal well electric heating device

Abstract

The application discloses a method for realizing efficient in-situ hydrogen production in a heavy oil reservoir by using an electric heating device of a horizontal well, and relates to the technical field of heavy oil reservoir development. The method comprises the following steps: S1, at least one horizontal injection well and one horizontal production well are arranged in the heavy oil reservoir to form a double horizontal well injection-production well pattern; an electric heating pipe is arranged in the downhole section of the horizontal injection well; S2, the electric heating pipe is started to gradually increase the reservoir temperature of the near-wellbore zone of the horizontal injection well to 600 DEG C to establish a high-temperature reaction field; the method can expand the swept volume of the in-situ hydrogen production reaction in the reservoir by arranging the double horizontal well injection-production well pattern formed by the horizontal injection well and the horizontal production well and by establishing a continuous high-temperature reaction field by the electric heating pipe, and can form a stable three-dimensional reaction space, so that the problems of insufficient vertical utilization and low reaction efficiency of the near-wellbore zone in the traditional straight well pattern can be solved.

Description

Technical Field

[0001] This invention relates to the field of heavy oil reservoir development technology, specifically to a method for efficient in-situ hydrogen production from heavy oil reservoirs using a horizontal well electric heating device. Background Technology

[0002] China possesses abundant heavy oil resources, but their complex physical and chemical properties make extraction difficult and inefficient. Heavy oil reservoirs are challenging to develop due to their high viscosity and poor fluidity. In the later stages of development, heavy oil reservoirs exhibit high water content and low oil saturation. In-situ gasification of heavy oil reservoirs for hydrogen production is an effective method for sustainable development. This method not only extracts heavy oil resources but also stores carbon dioxide. Hydrogen energy, as a clean energy source, has diverse applications, such as heating and power generation. However, common methods of hydrogen production through water electrolysis are energy-intensive and costly. Using reservoirs as underground reactors and crude oil resources as reactants for underground hydrogen production is an emerging approach. The current main idea is to inject oxygen-containing gas into the reservoir, causing partial combustion of the oil and gas. This provides the necessary temperature for hydrogen production and supplies gases such as carbon dioxide. High-temperature steam is also injected, followed by the reaction to produce hydrogen under high-temperature conditions.

[0003] To address these issues, a new hydrogen production method needs to be developed to improve hydrogen production efficiency, energy utilization, and fuel utilization, while reducing costs and achieving efficient in-situ hydrogen production from heavy oil reservoirs. Based on the current problems in in-situ hydrogen production from heavy oil, this paper proposes a method to generate a high-temperature reaction field underground using a horizontal well electric heating device. This is combined with a network of horizontal and vertical wells to inject a hydrogen-producing catalyst, further expanding the underground reaction volume and efficiently producing hydrogen. Furthermore, this method achieves efficient in-situ underground hydrogen production by adjusting the injection and production parameters. Summary of the Invention

[0004] The purpose of this invention is to provide a method for efficient in-situ hydrogen production from heavy oil reservoirs using a horizontal well electric heating device, in order to solve the problems of low hydrogen production efficiency, low energy and fuel utilization, high cost, insufficient vertical utilization of traditional vertical well networks, and low near-wellbore reaction efficiency in the existing technology.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a method for efficient in-situ hydrogen production from heavy oil reservoirs using a horizontal well electric heating device, comprising the following steps:

[0006] S1. Deploy at least one horizontal injection well and one horizontal production well in the heavy oil reservoir to form a dual horizontal well injection-production network; install a downhole electric heating pipe in the downhole section of the horizontal injection well;

[0007] S2. Activate the downhole electric heating pipe to gradually raise the reservoir temperature in the near-wellbore zone of the horizontal injection well to 600°C in order to establish a high-temperature reaction field;

[0008] S3. Injecting deoxygenated air into the reservoir through the horizontal injection well, wherein the deoxygenated air carries a high-temperature resistant gaseous nanocatalyst.

[0009] S4. In the high-temperature reaction field, the heavy oil undergoes thermal cracking and incomplete oxidation to generate a mixed gas containing hydrogen, methane, carbon oxides and coke.

[0010] S5. A multi-stage hydrogen-methane separation membrane system is installed in the downhole section of the horizontal production well to separate the mixed gas generated in step four and obtain high-purity hydrogen and methane.

[0011] S6. Part or all of the methane separated in step S5 is reinjected into the heavy oil reservoir through the horizontal injection well, where it undergoes a reforming reaction under high temperature and catalyst to generate hydrogen again.

[0012] S7. Water is injected into the reservoir through the horizontal injection well. The water forms near-critical water under the high temperature and high pressure environment of the reservoir. It undergoes water-gas conversion reaction and coke gasification reaction with carbon oxides and coke produced by incomplete oxidation and pyrolysis, and continuously produces hydrogen.

[0013] Furthermore, in step S2, the downhole electric heating tube is started using a stepped heating method, specifically: first, the temperature is increased to 300°C at a rate of 50°C per hour, and after stabilizing for 2 hours, the temperature is increased to 600°C at a rate of 30°C per hour; a distributed fiber optic temperature sensor is used to monitor the temperature of the horizontal well section in real time, and the heating power of the downhole electric heating tube is automatically adjusted according to the monitored temperature through the electrical control cabinet.

[0014] Further, in step S3, the injection flow rate of the oxygen-depleted air is 5-10 m³ / min, and the injection pressure is 5-10 MPa; the gas-phase nanocatalyst is nano-iron oxide or nano-nickel oxide.

[0015] Further, in step S5, the separation process of the hydrogen-methane multi-stage separation membrane system includes:

[0016] The mixed gas first enters the primary membrane module, where hydrogen with a purity of 50-60% and methane with a purity of 80-85% are separated.

[0017] The hydrogen separated in the first stage enters the second-stage membrane module for purification to a purity of 80-90%.

[0018] The hydrogen separated in the second stage enters the third-stage membrane module, ultimately yielding high-purity hydrogen with a purity of over 95%.

[0019] The methane trapped by each membrane module is collected and then reinjected or transported out through pipelines.

[0020] Furthermore, the membrane module used in the hydrogen-methane multi-stage separation membrane system is a ceramic membrane or MOFs composite membrane that is resistant to high and low temperatures, and the structure is a hollow fiber structure. The separation driving force is the natural pressure difference between the feed side and the permeate side.

[0021] Further, in step S6, the injection flow rate of reinjected methane is 2-5 m³ / min, and the injection pressure is 8-15 MPa; the reforming reaction includes one or more of the following: methane cracking reaction, methane steam reforming reaction, and methane carbon dioxide reforming reaction.

[0022] Furthermore, in step S7, the pressure of the injected water is 15-20 MPa, forming near-critical water in a reservoir environment with a temperature of 600℃ and a pressure of 20 MPa or higher; the water-gas conversion reaction is CO + H2O ⇌ CO2 + H2, and the coke gasification reaction is C + H2O ⇌ CO + H2.

[0023] Furthermore, in step S3, the gas carrying the gaseous nanocatalyst is uniformly distributed downhole.

[0024] Furthermore, in step S5, the direct export of hydrogen and the reinjection or export of methane are achieved through the downhole hydrogen separation and export pipeline and the downhole methane separation and export reinjection pipeline integrated into the hydrogen-methane multi-stage separation membrane system.

[0025] Compared with existing technologies, the present invention provides a method for efficient in-situ hydrogen production from heavy oil reservoirs using a horizontal well electric heating device. By deploying a dual horizontal well injection-production well network consisting of horizontal injection wells and horizontal production wells, and combining this with the establishment of a continuous high-temperature reaction field using downhole electric heating pipes, the swept volume of the in-situ hydrogen production reaction in the reservoir is effectively expanded, forming a stable three-dimensional reaction space. This overcomes the problems of insufficient vertical utilization of traditional vertical well networks and low reaction efficiency in the near-wellbore zone, significantly improving hydrogen production efficiency and single-well productivity.

[0026] By employing the injection of oxygen-reduced air carrying high-temperature resistant gaseous nanocatalysts, and combining this with the subsequent injection of water to form a near-critical water environment, a continuous reaction chain of "incomplete oxidation - thermal cracking - water-gas conversion - coke gasification" was constructed. This achieved efficient conversion of reactants and full utilization of hydrogen, thereby significantly improving the integrity of the hydrogen production reaction and the final yield of hydrogen while avoiding the consumption of generated hydrogen.

[0027] By installing a multi-stage membrane separation system with integrated hydrogen and methane separation and output pipelines in the downhole of the horizontal production well, in-situ efficient separation and purification of hydrogen and methane in the produced gas is achieved. Methane can be intelligently reinjected to participate in the reforming reaction, thus constructing an integrated system for downhole product separation and reactant recycling. While directly obtaining high-purity hydrogen products, carbon resources are recycled, improving process economy and resource utilization. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this invention. For those skilled in the art, other drawings can be obtained based on these drawings.

[0029] Figure 1 This is a schematic diagram of a method provided in an embodiment of the present invention;

[0030] Figure 2 A schematic diagram of a multi-stage hydrogen-methane purification downhole separation membrane device provided in an embodiment of the present invention;

[0031] Figure 3 This is a flowchart of a method provided in an embodiment of the present invention.

[0032] Explanation of reference numerals in the attached figures:

[0033] 1. Heavy oil reservoir; 2. Horizontal injection well; 3. Downhole electrically heated pipe; 4. Horizontal production well; 5. Hydrogen-methane multi-stage separation membrane system; 6. Downhole hydrogen separation and export pipeline; 7. Downhole methane separation and export / reinjection pipeline; 8. Gasification reaction hydrogen production area; 5-1. Methane separation pipeline of primary membrane module; 5-2. Methane separation pipeline of secondary membrane module; 5-3. Methane separation pipeline of tertiary membrane module; 5-4. Hydrogen separation pipeline of primary membrane module; 5-5. Hydrogen separation pipeline of secondary membrane module; 5-6. Hydrogen separation pipeline of tertiary membrane module. Detailed Implementation

[0034] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0035] As attached Figure 1 To be continued Figure 3 As shown:

[0036] Example 1:

[0037] This invention provides a method for efficient in-situ hydrogen production from heavy oil reservoirs using a horizontal well electric heating device, comprising the following steps:

[0038] Target reservoir and well pattern deployment:

[0039] A typical heavy oil reservoir was selected as target heavy oil reservoir 1. This reservoir has a depth of 800 meters, an effective thickness of 15 meters, a formation porosity of 25%, a permeability of 500 millidarcy, and a surface degassed heavy oil viscosity of 5000 mPa·s. A dual-horizontal well injection-production well network was deployed in this reservoir. The horizontal sections of both horizontal injection well 2 and horizontal production well 4 are 400 meters long, located vertically within the same reservoir, with a designed horizontal spacing of 80 meters.

[0040] Installation and initialization of key equipment:

[0041] Within the horizontal section of the injection well 2, a high-temperature, corrosion-resistant mineral-insulated (MI) cable-type downhole electric heating pipe 3 is installed. At the end of the horizontal section of the production well 4, a hydrogen-methane multi-stage separation membrane system 5 is installed. This system is connected to the surface hydrogen collection system and methane treatment unit via a downhole hydrogen separation and export pipeline 6 and a downhole methane separation and export / reinjection pipeline 7, respectively. Simultaneously, a distributed fiber optic temperature sensing system is deployed in the wellbore and near-wellbore area of ​​both the injection and production wells to monitor temperature field changes in real time.

[0042] Establish a high-temperature reaction field:

[0043] Start the downhole electric heating pipe 3 in horizontal injection well 2. A stepped heating strategy is adopted to protect the equipment and heat the reservoir evenly: first, the bottom hole temperature is increased from the initial 40°C to 300°C at a rate of 50°C per hour, and maintained at this temperature for 2 hours to allow heat to be conducted to the deeper reservoir; then, the temperature is increased at a rate of 30°C per hour, and finally the temperature of the reservoir around the horizontal well section is stabilized at 600°C, thereby establishing a large-scale, continuous and stable high-temperature reaction field.

[0044] Injecting reactants and catalysts:

[0045] Simultaneously with electric heating, deoxygenated air is injected into the already high-temperature reservoir through horizontal injection well 2. The deoxygenated air has an oxygen volume concentration of 15% and is continuously injected via a surface pressurization device at an injection pressure of 8 MPa and a flow rate of 8 m³ / min. This deoxygenated air flow uniformly carries pre-prepared high-temperature resistant gaseous nanocatalysts, consisting of iron oxide (Fe₂O₃) nanoparticles with an average particle size of 50 nanometers. By optimizing the injection process and airflow distribution, the catalyst can effectively enter and distribute within the reservoir pores with the airflow.

[0046] In-situ hydrogen production reaction start-up:

[0047] In a high-temperature reaction field of 600℃, heavy oil undergoes a series of complex chemical reactions with deoxygenated air and catalyst:

[0048] Thermal cracking reaction: The heavy components in heavy oil crack to produce light hydrocarbons, methane and hydrogen.

[0049] Incomplete oxidation reaction: Heavy oil reacts with a limited concentration of oxygen to produce carbon monoxide (CO), carbon dioxide (CO2) and some hydrogen, while also producing coke deposits.

[0050] These reactions continue deep within the reservoir (i.e., the hydrogen production zone 8 of the gasification reaction), generating a mixed gas rich in hydrogen, methane, carbon monoxide, and carbon dioxide.

[0051] Product separation and methane reinjection:

[0052] The mixed gas generated by the reaction flows to the horizontal production well 4 under the drive of formation pressure. The gas then enters the downhole hydrogen-methane multi-stage separation membrane system 5. This system uses alumina ceramic hollow fiber membrane modules that can withstand temperatures up to 600℃, utilizing the natural pressure difference across the membrane as the separation driving force.

[0053] The mixed gas first enters the primary membrane module, where hydrogen permeates preferentially, resulting in hydrogen with a purity of approximately 55%, while retaining methane with a purity of approximately 82%.

[0054] The first-stage permeate gas enters the second-stage membrane module for further purification, increasing the hydrogen purity to 85%.

[0055] The secondary permeate gas eventually enters the tertiary membrane module, producing high-purity hydrogen with a purity of up to 96%. This hydrogen is then directly transported to the surface for collection and utilization through a dedicated downhole hydrogen separation and export pipeline 6.

[0056] The methane gas trapped by each membrane module is collected and reinjected into the high-temperature area near the wellbore of the horizontal injection well 2 through the downhole methane separation and reinjection pipeline 7, with a flow rate of 3 m³ / min and a pressure of 10 MPa by the surface booster equipment.

[0057] Near-critical water reaction and system circulation:

[0058] The reinjected methane undergoes a methane steam reforming reaction (CH4 + H2O ⇌ CO + 3H2) under the combined action of the high-temperature reservoir and the nanocatalyst, and then generates hydrogen again.

[0059] Simultaneously, treated boiler water was injected into the reservoir through horizontal injection well 2 at a pressure of 18 MPa. The water rapidly transformed into near-critical water under the reservoir's high temperature of 600℃ and high pressure exceeding 20 MPa. This near-critical water exhibits extremely high activity, undergoing coke gasification (C + H₂O ⇌ CO + H₂) with the previously generated coke, and a water-gas conversion reaction with carbon monoxide (CO + H₂O ⇌ CO₂ + H₂). These two reactions continuously consume solid residues and CO, while generating a large amount of hydrogen, thus significantly improving the final hydrogen yield and resource utilization efficiency.

[0060] System Operation and Results: Through the above steps, this system establishes a highly efficient and cyclical in-situ hydrogen production system. By monitoring and adjusting the electric heating power and gas and water injection parameters in real time via the ground control cabinet, the system can maintain long-term stable operation. Ultimately, the downhole membrane separation system continuously produces green hydrogen with a purity ≥96%, achieving efficient in-situ hydrogen production and resource utilization in heavy oil reservoirs.

[0061] Example 2:

[0062] This embodiment is basically the same as the previous embodiment. The difference is that by changing the type of gas-phase nanocatalyst and optimizing the injection parameters, efficient in-situ hydrogen production from heavy oil reservoirs can also be achieved, demonstrating the flexibility and universality of this technical solution.

[0063] The geological conditions of the heavy oil reservoir 1, the deployment of the dual horizontal well network (including the well spacing and horizontal section length of the horizontal injection well 2 and the horizontal production well 4), the model and stepped heating program of the downhole electric heating pipe 3 (i.e., first heating to 300°C at 50°C / hour and holding at that temperature for 2 hours, then heating to 600°C at 30°C / hour), and the hydrogen-methane multi-stage separation membrane system 5 installed in the horizontal production well 4 and its separation process (three-stage purification to finally obtain high-purity hydrogen) are all exactly the same as in Example 1.

[0064] Replacement of gas-phase nanocatalysts:

[0065] Unlike Example 1, which used iron oxide (Fe2O3) nanoparticles, this example uses nickel oxide (NiO) nanoparticles with an average particle size of 30 nanometers as the gas-phase nanocatalyst injected through horizontal injection well 2. This catalyst also possesses excellent high-temperature resistance (stable withstanding 600℃) and high dispersibility, enabling it to effectively penetrate deep into the reservoir under the influence of deoxygenated air. In preliminary laboratory evaluations, this nano-nickel oxide catalyst exhibited high catalytic activity for methane reforming and water-gas conversion reactions.

[0066] Optimization and adjustment of oxygen-reduced air injection parameters:

[0067] This embodiment specifically adjusts the composition and injection parameters of the deoxygenated air to better match the reaction characteristics of the nickel-based catalyst and explore optimal hydrogen production efficiency:

[0068] Oxygen concentration: The oxygen volume concentration in the deoxygenated air was reduced from 15% in Example 1 to 10%. The purpose of this measure is to further enhance the incomplete oxidation reaction and inhibit the complete combustion of heavy oil, thereby providing heat for the reaction and generating more carbon monoxide (CO) for subsequent water-gas conversion reactions and coke as a solid-phase reactant.

[0069] Injection flow rate and pressure: The injection flow rate of deoxygenated air was adjusted from 8 m³ / min to 5 m³ / min, while the injection pressure was increased from 8 MPa to 10 MPa. Injecting at a lower flow rate and higher pressure is beneficial for prolonging the contact and reaction residence time of the reactant gas, catalyst, and heavy oil in the high-temperature reservoir, and for promoting the spread of the injected gas to deeper reservoirs, thereby potentially improving the hydrogen yield and fuel utilization rate of a single reaction cycle.

[0070] The system was started and operated according to the modified parameters. Once the downhole temperature field stabilized at 600℃, low-oxygen-concentration (10%) air carrying nano-nickel oxide catalyst was injected. Monitoring data showed that the thermal cracking and incomplete oxidation reactions were successfully initiated, and horizontal production well 4 began producing mixed gas.

[0071] After the mixed gas enters the hydrogen-methane multi-stage separation membrane system 5, it is efficiently separated. Finally, high-purity hydrogen with a purity of no less than 95% is obtained through the downhole hydrogen separation and export pipeline 6. Simultaneously, the separated methane is reinjected into the formation through the downhole methane separation and export reinjection pipeline 7, where a significant methane reforming reaction occurs under the highly efficient catalysis of a nano-nickel oxide catalyst, continuously replenishing the system with hydrogen.

[0072] Conclusion: This embodiment confirms that replacing the gas-phase nanocatalyst with nano-nickel oxide (NiO), and accordingly adjusting the oxygen concentration of the deoxygenated air to 10%, the injection flow rate to 5 m³ / min, and the pressure to 10 MPa, can also successfully achieve in-situ efficient hydrogen production from heavy oil reservoirs.

[0073] Example 3:

[0074] This embodiment describes the specific structure, workflow, and control method of a downhole multi-stage membrane separation and methane reinjection system.

[0075] The hydrogen-methane multi-stage separation membrane system 5 is directly installed in the downhole horizontal section of the horizontal production well 4, and its specific composition is as follows:

[0076] Membrane Module: The core of the system adopts a three-stage series metal-organic framework (MOF) composite hollow fiber membrane module. This membrane material is specially designed to operate stably for a long time in downhole environments with high temperature of 600℃ and high pressure of 20MPa, and has high selectivity for hydrogen and methane.

[0077] Piping Integration: The system integrates two independent downhole output pipelines.

[0078] Downhole hydrogen separation and export pipeline 6: This is a dedicated pipeline that starts from the permeate side outlet of the three-stage membrane module and extends directly to the surface hydrogen purification and storage unit.

[0079] Downhole Methane Separation and Reinjection Pipeline 7: This is a dedicated pipeline used to collect and transport methane-enriched gas from the choke side of all membrane modules. This pipeline connects at the wellhead to an automatically controlled three-way valve and a small downhole booster pump.

[0080] Detailed process flow of multi-stage membrane separation:

[0081] The mixed gas (mainly composed of H2, CH4, CO, and CO2) from the hydrogen production zone 8 of the gasification reaction enters the hydrogen-methane multi-stage separation membrane system 5 under downhole pressure. The separation and purification process is as follows:

[0082] Primary separation: The mixed gas first enters the primary membrane module. Here, hydrogen (H2) preferentially permeates through the membrane wall, resulting in hydrogen with a purity of approximately 58% in the hydrogen separation line 5-4 of the primary membrane module. Most of the methane (CH4) and other gases are retained, forming a methane-enriched gas with a purity of approximately 81% in the methane separation line 5-1 of the primary membrane module.

[0083] Secondary separation: The hydrogen permeating from the primary membrane (58% purity) then enters the secondary membrane module for further purification. In the hydrogen separation line 5-5 of the secondary membrane module, the hydrogen purity is increased to 87%. The residual methane retained in the secondary membrane module flows into the methane separation line 5-2 of the secondary membrane module.

[0084] Three-stage separation: The hydrogen permeate from the second stage (87% purity) finally enters the third-stage membrane module. In the hydrogen separation pipeline 5-6 of the third-stage membrane module, high-purity hydrogen with a purity of up to 97.5% is produced. This gas is directly transported to the surface through the downhole hydrogen separation and export pipeline 6, and can be used as product gas without secondary treatment.

[0085] Methane aggregation: All methane-enriched gas from the primary, secondary, and tertiary membrane modules is aggregated into the downhole methane separation and reinjection pipeline 7 via pipelines 5-1, 5-2, and 5-3, respectively. The methane purity in the aggregated gas mixture is maintained above 83%.

[0086] Intelligent control strategy for methane reinjection:

[0087] The high-purity methane gas collected faces two path choices in the downhole methane separation and reinjection pipeline 7. This process is intelligently controlled by the surface control system based on real-time operating conditions.

[0088] Monitoring and Decision-Making: The system analyzes the hydrogen production rate and purity from the wellhead of horizontal production well 4 in real time. When the hydrogen production rate is detected to be lower than the preset threshold, or when the downhole gas composition analyzer detects a decrease in the activity of the reforming reaction zone, the control system determines that it is necessary to strengthen methane reinjection to replenish the reactants.

[0089] Injection Execution: The control system then instructs the automatic control of the three-way valve to direct most or all of the collected methane gas into the reinjection process. A small downhole booster pump starts, injecting methane gas at a flow rate of 4 m³ / min and a pressure of 12 MPa through the pipeline into the 600°C high-temperature zone near the wellbore of horizontal injection well 2.

[0090] The reaction after reinjection: Under high temperature and with the pre-placed nanocatalyst (whether Fe2O3 in Example 1 or NiO in Example 2), the reinjected methane rapidly undergoes a methane-carbon dioxide reforming reaction (CH4 + CO2 ⇌ 2CO + 2H2) and a methane cracking reaction (CH4 ⇌ C + 2H2), generating additional hydrogen and carbon monoxide. The carbon monoxide can then participate in the water-gas conversion reaction to continue producing hydrogen. This process achieves the recycling of carbon resources and an increase in hydrogen production.

[0091] External output mode: When the system produces hydrogen stably and no additional reactants are needed, the three-way valve can direct some methane to the ground for collection and utilization as a byproduct.

[0092] Conclusion: This embodiment details the specific implementation of the downhole multi-stage membrane separation and reinjection system, demonstrating that this subsystem can efficiently and stably complete in-situ hydrogen purification and intelligent methane recycling in the harsh downhole environment described in this invention, which is key to ensuring the efficient operation of the entire method.

[0093] The foregoing has only described certain exemplary embodiments of the present invention by way of illustration. Undoubtedly, those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the foregoing drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A method for efficient in-situ hydrogen production from heavy oil reservoirs using a horizontal well electric heating device, characterized in that, Includes the following steps: S1. Deploy at least one horizontal injection well (2) and one horizontal production well (4) in the heavy oil reservoir (1) to form a dual horizontal well injection and production network; install a downhole electric heating pipe (3) in the downhole section of the horizontal injection well (2). S2. Start the downhole electric heating pipe (3) to gradually raise the reservoir temperature in the near-well zone of the horizontal injection well (2) to 600°C in order to establish a high-temperature reaction field; S3. Inject deoxygenated air into the reservoir through the horizontal injection well (2), wherein the deoxygenated air carries a high-temperature resistant gaseous nanocatalyst. S4. In the high-temperature reaction field, the heavy oil undergoes thermal cracking and incomplete oxidation to generate a mixed gas containing hydrogen, methane, carbon oxides and coke. S5. A hydrogen-methane multi-stage separation membrane system (5) is installed in the downhole section of the horizontal production well (4) to separate the mixed gas generated in step four and obtain high-purity hydrogen and methane. S6. Part or all of the methane separated in step S5 is reinjected into the heavy oil reservoir (1) through the horizontal injection well (2), and undergoes a reforming reaction under high temperature and catalyst to generate hydrogen again. S7. Water is injected into the reservoir through the horizontal injection well (2). The water forms near-critical water under the high temperature and high pressure environment of the reservoir. It reacts with carbon oxides and coke produced by incomplete oxidation and pyrolysis to produce water-gas conversion reaction and coke gasification reaction, and continuously produces hydrogen.

2. The method for efficient in-situ hydrogen production from heavy oil reservoirs using a horizontal well electric heating device according to claim 1, characterized in that, In step S2, the downhole electric heating tube (3) is started using a stepped heating method, specifically: first, the temperature is raised to 300°C at a rate of 50°C per hour, and after stabilizing for 2 hours, the temperature is raised to 600°C at a rate of 30°C per hour; a distributed fiber optic temperature sensor is used to monitor the temperature of the horizontal well section in real time, and the heating power of the downhole electric heating tube (3) is automatically adjusted by the electrical control cabinet according to the monitored temperature.

3. The method for efficient in-situ hydrogen production from heavy oil reservoirs using a horizontal well electric heating device according to claim 1, characterized in that, In step S3, the injection flow rate of the oxygen-reduced air is 5-10 m³ / min, and the injection pressure is 5-10 MPa; the gas-phase nanocatalyst is nano-iron oxide or nano-nickel oxide.

4. The method for efficient in-situ hydrogen production from heavy oil reservoirs using a horizontal well electric heating device according to claim 1, characterized in that, In step S5, the separation process of the hydrogen-methane multi-stage separation membrane system (5) includes: The mixed gas first enters the primary membrane module, where hydrogen with a purity of 50-60% and methane with a purity of 80-85% are separated. The hydrogen separated in the first stage enters the second-stage membrane module for purification to a purity of 80-90%. The hydrogen separated in the second stage enters the third-stage membrane module, ultimately yielding high-purity hydrogen with a purity of over 95%. The methane trapped by each membrane module is collected and then reinjected or transported out through pipelines.

5. A method for efficient in-situ hydrogen production from heavy oil reservoirs using a horizontal well electric heating device according to claim 4, characterized in that, The hydrogen-methane multi-stage separation membrane system (5) uses a high- and low-temperature resistant ceramic membrane or MOFs composite membrane with a hollow fiber structure. The separation driving force is the natural pressure difference between the feed side and the permeate side.

6. The method for efficient in-situ hydrogen production from heavy oil reservoirs using a horizontal well electric heating device according to claim 1, characterized in that, In step S6, the injection flow rate of reinjected methane is 2-5 m³ / min, and the injection pressure is 8-15 MPa; the reforming reaction includes one or more of the following: methane cracking reaction, methane steam reforming reaction, and methane carbon dioxide reforming reaction.

7. A method for efficient in-situ hydrogen production from heavy oil reservoirs using a horizontal well electric heating device according to claim 1, characterized in that, In step S7, the pressure of the injected water is 15-20 MPa, and near-critical water is formed in a reservoir environment with a temperature of 600℃ and a pressure of 20 MPa or higher; the water-gas conversion reaction is CO + H2O ⇌ CO2 + H2, and the coke gasification reaction is C + H2O ⇌ CO + H2.

8. A method for efficient in-situ hydrogen production from heavy oil reservoirs using a horizontal well electric heating device according to claim 1, characterized in that, In step S3, the gas carrying the gaseous nanocatalyst is uniformly distributed downhole.

9. A method for efficient in-situ hydrogen production from heavy oil reservoirs using a horizontal well electric heating device according to claim 1, characterized in that, In step S5, the direct export of hydrogen and the reinjection or export of methane are achieved through the downhole hydrogen separation and export pipeline (6) and the downhole methane separation and export reinjection pipeline (7) integrated into the hydrogen-methane multi-stage separation membrane system (5).

Images