Method and device for enhanced heat and mass transfer rate in horizontal well groups

Abstract

The application discloses a kind of oil exploitation method and device for strengthening the rate of horizontal well group heat mass transfer, the method comprises: when meeting preset heating condition, start heating, at this time, close the production well in the horizontal well group, open the injection well in the horizontal well group, open the electric heater arranged in the injection well, and inject hot gas into the injection well, wherein the heating condition comprises: the daily gas production of the production well is less than the preset production value and the horizontal well group produces horizontal fracture and / or vertical fracture meeting the requirements;After heating is completed, the injection well is closed, the production well is opened, and oil exploitation is started.The application proposes a synergistic heating method combining electric heating and hot gas injection, and uses a cyclic production mode, significantly improves the reservoir heating rate and heat mass transfer efficiency, effectively improves the oil exploitation effect and efficiency of the horizontal well group.

Description

Technical Field

[0001] This invention relates to the field of oil extraction technology, and more specifically, to an oil extraction method and apparatus for enhancing the heat and mass transfer rate of horizontal well groups. Background Technology

[0002] Medium- and low-maturity shale oil and oil shale resources are abundant and are important alternative energy sources to conventional oil and gas, but they require heating and maturation before extraction. In-situ underground conversion technology has the advantages of small footprint and environmental friendliness, and has become one of the core technologies for the efficient development of medium- and low-maturity shale oil. According to the heat transfer method, in-situ conversion technology can be divided into two categories: heat conduction and heat convection. According to the heating method, it can be divided into four categories: electric conduction heating, hot fluid heating, combustion heating, and radiation heating. Among them, electric conduction heating and hot fluid heating are relatively mature, with multiple processes already available. Combustion heating technology has high energy utilization, but high extraction costs and complex processes. Radiation heating technology can achieve uniform heating, but the equipment is expensive and the heating range is limited.

[0003] Currently, the main heating method in in-situ conversion technology is electric heating, but electric heating alone has low heating efficiency. How to improve the heating efficiency of single electric heating and the low efficiency of heat transfer, and improve the heating efficiency of reservoirs to enhance the oil extraction efficiency and effectiveness of medium- and low-maturity shale oil and oil shale, is an urgent problem that existing technologies need to solve. Summary of the Invention

[0004] In order to solve at least one of the technical problems in the background art, the present invention proposes a method and apparatus for oil extraction that enhances the heat and mass transfer rate of horizontal well groups.

[0005] To achieve the above objectives, according to one aspect of the present invention, a method for enhancing the heat and mass transfer rate of oil extraction using horizontal well groups is provided, the method comprising:

[0006] When the preset heating conditions are met, heating begins. At this time, the production well in the horizontal well group is closed, the injection well in the horizontal well group is opened, the electric heater installed in the injection well is turned on, and hot gas is injected into the injection well. The heating conditions include: the daily gas production of the production well is less than the preset production value and the horizontal well group produces horizontal and / or vertical fractures that meet the requirements.

[0007] After heating is complete, the injection well is closed and the production well is opened to begin oil extraction.

[0008] Optionally, the oil extraction method for enhancing heat and mass transfer rate in horizontal well groups further includes:

[0009] During oil extraction, the rate of gas discharge is controlled to be below a preset rate, and the discharged gas is collected.

[0010] Optionally, the horizontal well group may be used for reservoir stimulation via volumetric fracturing.

[0011] Optionally, the hot gas is carbon dioxide gas with a temperature not lower than 300°C.

[0012] Optionally, the heating section of the electric heater is located within the reservoir, the power of each meter of the heating section of the electric heater is 100W to 2000W, and the surface heating temperature of the electric heater is 350℃ to 500℃.

[0013] Optionally, vertical fractures must be designed so that the fracture height does not exceed the oil layer thickness; horizontal fractures must be designed to use zipper-style cross fracturing, and the distance between the main fractures must not exceed 2 / 3 of the well spacing.

[0014] Optionally, the oil extraction method for enhancing heat and mass transfer rate in horizontal well groups further includes:

[0015] During the heating process, when the injection pressure of the hot gas reaches a preset pressure value and the injection speed of the hot gas drops below the preset injection speed, the injection well is closed, the injection of the hot gas is stopped, and the electric heater continues to work while the well is shut down for a preset duration.

[0016] To achieve the above objectives, according to another aspect of the present invention, an oil extraction apparatus for enhancing the heat and mass transfer rate of a horizontal well group is provided, the apparatus comprising:

[0017] A heating control unit is used to start heating when preset heating conditions are met. At this time, the production well in the horizontal well group is closed, the injection well in the horizontal well group is opened, the electric heater installed in the injection well is turned on, and hot gas is injected into the injection well. The heating conditions include: the daily gas production of the production well is less than the preset production value and the horizontal well group produces horizontal and / or vertical cracks that meet the requirements.

[0018] The production control unit is used to close the injection well and open the production well to begin oil extraction after heating is complete.

[0019] Optionally, the oil extraction apparatus for enhancing heat and mass transfer rate in the horizontal well group further includes:

[0020] An exhaust control unit is used to control the rate of exhaust gas to below a preset rate and to collect the exhaust gas during oil extraction.

[0021] Optionally, the heating control unit is further configured to, during the heating process, close the injection well and stop injecting the hot gas when the injection pressure of the hot gas reaches a preset pressure value and the injection speed of the hot gas drops below a preset injection speed, so that the electric heater continues to work and simultaneously perform a preheating process for a preset duration.

[0022] To achieve the above objectives, according to another aspect of the present invention, a computer device is also provided, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the steps of the above-described method for enhancing the thermal and mass transfer rate of a horizontal well group in oil extraction.

[0023] To achieve the above objectives, according to another aspect of the present invention, a computer-readable storage medium is also provided, on which a computer program / instruction is stored, which, when executed by a processor, implements the steps of the above-described oil extraction method for enhancing the thermal and mass transfer rate of horizontal well groups.

[0024] To achieve the above objectives, according to another aspect of the present invention, a computer program product is also provided, comprising a computer program / instructions that, when executed by a processor, implement the steps of the above-described oil extraction method for enhancing the thermal and mass transfer rate of horizontal well groups.

[0025] The beneficial effects of this invention are as follows:

[0026] This invention proposes a synergistic heating method combining electric heating and hot gas injection, as well as a cyclic extraction mode, which significantly improves the reservoir heating rate and heat and mass transfer efficiency, effectively enhancing the effect and efficiency of horizontal well group oil extraction, and providing an innovative and economically feasible technical solution for the efficient development of medium and low maturity shale oil. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. In the drawings:

[0028] Figure 1 This is a first flowchart of the oil extraction method for enhancing heat and mass transfer rate with horizontal well groups according to an embodiment of the present invention;

[0029] Figure 2 This is a second flowchart of the oil extraction method for enhancing heat and mass transfer rate in horizontal well groups according to an embodiment of the present invention;

[0030] Figure 3This is a first structural block diagram of an oil extraction device for enhancing heat and mass transfer rate in a horizontal well group according to an embodiment of the present invention.

[0031] Figure 4 This is a second structural block diagram of an oil extraction device for enhancing heat and mass transfer rate in a horizontal well group according to an embodiment of the present invention.

[0032] Figure 5 This is a schematic diagram of a computer device according to an embodiment of the present invention. Detailed Implementation

[0033] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0034] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0035] It should be noted that the terms "comprising" and "having" and any variations thereof in the specification, claims and accompanying drawings of this invention are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to such processes, methods, products or devices.

[0036] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0037] Figure 1 This is a first flowchart of an oil extraction method for enhancing heat and mass transfer rate in horizontal well groups according to an embodiment of the present invention, as shown below. Figure 1 As shown, in one embodiment of the present invention, the oil extraction method for enhancing the heat and mass transfer rate of horizontal well groups includes steps S101 and S102.

[0038] Step S101: When the preset heating conditions are met, heating begins. At this time, the production well in the horizontal well group is closed, the injection well in the horizontal well group is opened, the electric heater installed in the injection well is turned on, and hot gas is injected into the injection well. The heating conditions include: the daily gas production of the production well is less than the preset production value, and the horizontal well group produces horizontal and / or vertical fractures that meet the requirements.

[0039] In this step, the heating process is initiated based on a comprehensive assessment of the reservoir and well group. First, the system determines whether preset heating conditions are met. These conditions include two key factors: the daily gas production rate of the production well and the formation of fractures. The heating process is only initiated when the daily gas production rate of the production well is lower than the preset production value. This is because a lower daily gas production rate usually indicates lower reservoir pressure, meaning the oil or gas resources in the reservoir have not yet been fully exploited. In this case, the heating process can support subsequent oil and gas flow. Additionally, the fracture conditions within the well group also affect whether heating is initiated. Horizontal and vertical fractures significantly affect the propagation and transfer of hot gas. In this invention, the well group needs to meet certain fracture conditions, such as fracture length and direction, to ensure that hot gas can be evenly distributed and penetrate deep into the reservoir, thereby improving heat transfer efficiency. Heating treatment will only begin when the fractures meet the requirements.

[0040] In this invention, the production well is first shut down during the heating process to avoid interference from oil production operations. Then, the injection well is opened, and hot gas (such as CO2) is injected to raise the reservoir temperature. Furthermore, an electric heater within the well is activated to further enhance the reservoir heating effect. By providing additional heat, the electric heater helps raise the reservoir temperature, promotes oil and gas flow, and reduces oil and gas viscosity.

[0041] In one embodiment of the present invention, the preset production value can be flexibly adjusted according to the reservoir size, oilfield characteristics, and extraction experience to ensure optimal results during reservoir heating. In an optional embodiment, the preset production value is specifically 200m³. 3 / d.

[0042] Step S102: After heating is complete, the injection well is closed and the production well is opened to begin oil extraction.

[0043] In this invention, once the heating process is complete, i.e., the reservoir temperature reaches the preset target, the hot gas injection process in the injection well will stop. During this process, the injection well is shut down, and the injection of hot gas is stopped. Then, the production well is reopened, and oil extraction begins. In this way, the heated reservoir can provide highly fluid oil and gas, facilitating extraction by the production well and improving the efficiency and effectiveness of oil extraction.

[0044] Therefore, this invention combines the daily gas production of the production well with the fracture formation to precisely control heating conditions. During the heating process, the combined heating method using hot gas and an electric heater not only effectively increases the reservoir temperature but also controls the rate and range of temperature increase, avoiding resource waste caused by overheating. Furthermore, through precise operational control, the system promptly switches to oil extraction mode after heating is complete to ensure maximum resource extraction.

[0045] like Figure 2 As shown, in one embodiment of the present invention, the oil extraction method for enhancing the heat and mass transfer rate of horizontal well groups of the present invention further includes step S103.

[0046] Step S103: During oil extraction, control the rate of gas discharge to below a preset rate and collect the discharged gas.

[0047] During extraction, the gas emission rate in production wells is typically influenced by various factors, including reservoir pressure, oil and gas flowability, and extraction methods. To ensure proper regulation of oil and gas flowability and prevent excessive gas emission, the system needs to precisely control the gas emission rate. An excessively high emission rate can lead to uneven distribution of hot gases within the reservoir, affecting heat and mass transfer efficiency and consequently reducing oil recovery. Furthermore, excessively rapid gas emission can also result in excessively low reservoir pressure, hindering subsequent oil and gas extraction.

[0048] Therefore, in step S103, the system sets a suitable upper limit for the gas discharge rate based on the reservoir size, the actual conditions of the oilfield, and expert experience. This upper limit ensures that the gas discharge is not too rapid, thereby maintaining stable pressure within the reservoir and promoting smoother oil and gas flow. In a specific embodiment, the preset gas discharge rate can be set to 2000 m³ / s. 3 / d. This value is not fixed and can be adjusted according to the reservoir characteristics, production progress, and technical requirements of the oilfield. For example, larger reservoirs may require higher gas emission rates, while smaller reservoirs may require lower rates to avoid excessively rapid gas emission affecting the thermodynamic state of the reservoir.

[0049] In this invention, in addition to controlling the gas emission rate, the emitted gas is also collected. By collecting the gas, its composition and quantity can be monitored in real time, providing data support for subsequent production decisions. In one embodiment of this invention, analysis of the emitted gas can determine reservoir pressure changes, temperature distribution, and oil and gas flowability, information crucial for adjusting gas injection strategies and production plans.

[0050] In one embodiment of the present invention, the horizontal well group employs volumetric fracturing for reservoir stimulation. The horizontal well group design of the present invention includes injection wells and production wells, with at least one injection well and at least four production wells. This configuration makes oil and gas extraction more efficient, enabling the extraction of oil from reservoirs at different locations and depths.

[0051] In one embodiment of the present invention, the horizontal well group employs volumetric fracturing to stimulate the reservoir, thereby improving its permeability and enhancing oil and gas flow. Volumetric fracturing involves injecting fracturing fluid under high pressure to create a complex network of fractures within the reservoir, thus expanding the stimulation area and improving the flow channels for oil and gas. Specifically, fracturing fluid is first pumped into the wellbore, gradually increasing the pressure to cause tensile fracturing of the reservoir rock and the formation of the main fracture. Subsequently, proppant is continuously injected to keep the fractures open and prevent them from closing. Multi-stage fracturing technology is used during the fracturing process to allow the fractures to extend fully at different layers, maximizing the reservoir stimulation effect. The volumetric fracturing method used in this invention can effectively improve the production efficiency of low-permeability reservoirs, enhance oil and gas recovery, and provide better channel conditions for subsequent heat and mass transfer.

[0052] In one embodiment of the present invention, the hot gas is carbon dioxide gas (CO2) with a temperature not lower than 300°C.

[0053] In one embodiment of the present invention, the heating section of the electric heater is located within the reservoir, the power of each meter of the heating section of the electric heater is 100W to 2000W, the surface heating temperature of the electric heater is 350°C to 500°C, and the electric heater includes at least one of a resistance heater, an electromagnetic heater, a radio frequency heater, and a DC electric heater.

[0054] In one embodiment of the invention, the heating section of the electric heater is located within the reservoir to directly heat the oil, gas, and rocks within the reservoir. Because the heater is located inside the reservoir, it allows for more precise control of heat transfer, ensuring that hot gases can fully diffuse to every area of ​​the reservoir. The primary function of the electric heater is to provide thermal energy, thereby reducing the viscosity of the oil layer or promoting the flow of oil and gas, making it easier to extract oil and gas from the reservoir.

[0055] In one embodiment of the present invention, the requirement for vertical fractures is that the fracture height does not exceed the thickness of the oil layer; the requirement for horizontal fractures is that zipper-type cross fracturing is used, and the distance between the main fractures does not exceed 2 / 3 of the well spacing.

[0056] In this invention, the presence of fractures is crucial for the effective transport of hot gases. A well-distributed network of horizontal and vertical fractures provides an efficient heat conduction path, allowing hot gases to rapidly penetrate all areas of the reservoir. Inadequate fractures, however, can lead to wasted heat or poor localized heating. Therefore, fracture design and control directly impact heating efficiency and subsequent oil extraction efficiency. To ensure optimal heating, this invention sets requirements for fracture quality before heating; the heating process can only be initiated when fractures meet these requirements. This design ensures that fracture formation is beneficial and meets the optimal requirements for reservoir development, thereby avoiding poor hot gas transport or wasted heat energy due to fracture issues.

[0057] In this invention, the requirement for vertical fractures is that the fracture height does not exceed the oil layer thickness. This requirement aims to limit the longitudinal development range of vertical fractures and ensure that the fracture depth does not exceed the oil layer thickness. Vertical fractures generally facilitate the vertical propagation of hot gases, but excessively deep fractures may lead to excessive heat diffusion, preventing effective concentration and utilization within the oil layer, thus affecting heating efficiency. By controlling the fracture depth, heat is concentrated within the effective oil layer area, improving the efficiency of hot gas transmission and contributing to optimized oil and gas recovery.

[0058] In this invention, the requirement for horizontal fractures is the use of zipper-style cross-fracture, with the distance between main fractures not exceeding 2 / 3 of the well spacing. Zipper-style cross-fracture is a fracturing technique commonly used in horizontal wells or multi-section wells. It optimizes the fracture network by alternately fracturing different fracture segments. The advantage of this method is that it can form an effective fracture network in multiple sections of a horizontal well, improving the seepage path of oil and gas and the efficiency of hot gas transmission, thereby increasing oil and gas recovery efficiency. The zipper-style cross-fracture operation method can effectively avoid the overdevelopment of a single fracture and prevent heat leakage or ineffective heating caused by excessively rapid local fracture expansion.

[0059] The requirement in this invention that the distance between the main fractures should not exceed 2 / 3 of the well spacing aims to optimize the spacing and distribution of horizontal fractures to ensure optimal interaction between them. Well spacing refers to the distance between two wells, and a certain distance is typically maintained in oil extraction to ensure effective oil and gas flow. Limiting the distance between the main fractures to 2 / 3 of the well spacing means that the fracture network will form within a more compact area, which helps improve fracture connectivity and the efficiency of hot gas transport. Smaller fracture spacing increases fracture density, allowing hot gas to propagate rapidly and uniformly heat the entire oil reservoir without wasting energy.

[0060] In one embodiment of the present invention, the oil extraction method for enhancing heat and mass transfer rate in horizontal well groups further includes:

[0061] During the heating process, when the injection pressure of the hot gas reaches a preset pressure value and the injection speed of the hot gas drops below the preset injection speed, the injection well is closed, the injection of the hot gas is stopped, and the electric heater continues to work while the well is shut down for a preset duration.

[0062] In this invention, the injection pressure of the hot gas (such as carbon dioxide) needs to meet certain requirements during the heating process. Controlling the injection pressure ensures that the hot gas can effectively penetrate into the reservoir and provide heating. If the injection pressure is too low, the hot gas may not be able to effectively penetrate the deeper parts of the reservoir, resulting in poor heating; while excessively high pressure may cause reservoir damage or even wellbore instability. Therefore, setting a preset pressure value is an optimized control of the heating process. In one embodiment of this invention, the preset pressure value ranges from 10 MPa to 20 MPa. This pressure range is selected based on a comprehensive consideration of reservoir size, gas characteristics, and expert experience. By reasonably controlling the injection pressure, it can be ensured that the hot gas is evenly distributed within the reservoir, effectively transferring heat energy and improving extraction efficiency.

[0063] In this invention, during the heating process, when the injection rate of the injected hot gas drops below a certain preset value, it indicates that the reservoir has fully absorbed the heat, the injection efficiency of the hot gas decreases, and continued injection may lead to resource waste. Therefore, the system stops injecting hot gas at this point. The purpose of controlling the preset injection rate is to ensure effective injection of hot gas while avoiding exceeding the reservoir's absorption capacity, thus ensuring economic efficiency. In one embodiment of this invention, the preset injection rate is 500m³ / h. 3 / d, the specific value of this injection rate is determined by the size of the reservoir and expert experience, and may be adjusted appropriately according to the characteristics of the actual reservoir. When the injection rate is lower than this preset value, injection is stopped to prevent ineffective gas injection and reduce operating costs.

[0064] In one embodiment of the present invention, the preset duration can be determined according to actual circumstances. In an optional embodiment, the preset duration can be 8 to 10 days.

[0065] In this invention, after the injection of hot gas is stopped, the system does not immediately terminate the heating process, but continues heating using an electric heater. The electric heater can continue to heat the reservoir even without hot gas; this stage is called the well-clogging stage. The purpose of well-clogging is to use the electric heater to maintain the reservoir temperature, ensuring that the reservoir maintains a relatively high temperature even without hot gas injection, and gradually permeating all parts of the oil layer, improving oil and gas flow. While the electric heater continues to operate, it effectively prevents the reservoir temperature from dropping, ensuring that the thermal energy of the oil layer is maintained at an ideal level, preparing for subsequent extraction processes.

[0066] In this invention, the setting of the well-sealing time plays a crucial role in the final oil and gas extraction effect. An excessively long well-sealing time may lead to unnecessary energy waste, while an excessively short time may fail to achieve effective heating, affecting the oil and gas recovery rate. Therefore, the preset well-sealing time needs to be scientifically and rationally set based on the specific reservoir conditions and heating effect. In one embodiment of this invention, the well-sealing time ranges from 8 to 10 days. This range is derived after a thorough analysis of reservoir characteristics and heating effect and can be adjusted appropriately according to actual conditions. The purpose of the well-sealing stage is to ensure that the heat within the reservoir is preserved to the maximum extent, while preparing for the next stage of oil extraction.

[0067] Therefore, this invention, by precisely controlling the injection pressure and rate of hot gas and stopping gas injection at the appropriate time to enter the well-closing stage, utilizes an electric heater to maintain a high temperature, ensuring that the heat energy within the reservoir is not lost and enhancing the heat gas transfer efficiency. Furthermore, the proper design of the well-closing stage can provide a good thermal energy guarantee for subsequent oil extraction processes, optimize oil and gas recovery rates, improve extraction efficiency, and ultimately achieve efficient resource utilization.

[0068] In one specific embodiment of the present invention, during the heating process, when the carbon dioxide gas (CO2) injection pressure reaches 10-20 MPa and the injection speed decreases to 500 m / s... 3 When the gas flow rate is below / d, close the injection well and stop gas injection. The electric heater continues to operate, and the well is kept closed for 8-10 days.

[0069] In one embodiment of the present invention, the method further includes:

[0070] The injection pressure and temperature of the hot gas during the heating stage were determined by triaxial rock mechanics experiments and X-ray diffraction analysis.

[0071] This invention utilizes heated triaxial rock mechanics experiments to test the changes in the mechanical properties of reservoir cores under different temperatures (e.g., 50℃ to 450℃) and pressures (e.g., 5 MPa to 15 MPa), particularly indices such as compressive strength and elastic modulus. These tests allow for the identification of a suitable range of gas injection temperature and pressure to ensure effective fracturing of the reservoir and improve hydrocarbon flowability. For example, experimental data shows that the optimal gas injection pressure is between 10 MPa and 20 MPa, and the optimal injection temperature range is between 300℃ and 450℃. This range effectively promotes fracture propagation while avoiding adverse effects.

[0072] Then, this invention utilizes X-ray diffraction (XRD) to analyze the changes in mineral composition in rock samples, particularly the expansion and thermal deformation characteristics of clay minerals. By understanding the effect of temperature on mineral composition, the temperature of hot gas injection can be optimized to ensure that excessive mineral expansion or reservoir stability is not affected by excessively high temperatures. Based on X-ray diffraction analysis data, this invention identifies a temperature range that ensures thermal fracturing of the reservoir is promoted without adversely affecting the minerals.

[0073] Based on the results of heated triaxial rock mechanics experiments and X-ray diffraction analysis, this invention determines an optimal hot gas injection temperature range. Specifically, through heated triaxial rock mechanics experiments, this invention determines that rocks exhibit optimal fracture propagation capacity under conditions of 300℃ to 400℃ and 10MPa to 20MPa; through X-ray diffraction analysis, it is determined that clay mineral expansion is controllable and reservoir structure is stable within this temperature range. Therefore, the gas injection temperature is optimized to 300℃ to 400℃, and the gas injection pressure is optimized to 10MPa to 20MPa.

[0074] In one embodiment of the present invention, the method further includes:

[0075] The injection volume of the hot gas during the heating stage was determined by nano-CT digital core testing.

[0076] In one embodiment of the present invention, this step determines the minimum and maximum injection volume of the hot gas during the heating phase.

[0077] In one embodiment of the present invention, nano-CT technology can be used to perform high-precision three-dimensional scanning of reservoir cores to obtain the pore structure, fracture characteristics, and oil and gas distribution of the cores. The scanning results can yield data on residual oil saturation and porosity of the cores. Combining the three-dimensional images of the cores, the distribution and saturation of oil and gas within the cores can be analyzed, and the required gas injection volume can be estimated by simulating the gas injection process. Based on this, the minimum and maximum gas injection volumes for the heating stage can be determined. The minimum injection volume ensures sufficient hot gas penetration into the reservoir to activate untapped oil and gas, while the maximum injection volume avoids resource waste or reservoir damage caused by excessive gas injection.

[0078] In one specific embodiment of the present invention, the reservoir is a horizontal cylindrical reservoir with a height of 20m and a radius of 6m, and the total volume of the reservoir is approximately 2252.2m³. 3 The injection wellbore is 20m long and 0.1m in radius. The production well spacing is 2m. The electric heater is 19m long and 0.02m in radius. The reservoir is a porous medium with a porosity of 0.1. The initial reservoir temperature is 20℃. The heat consumption rate is 2KW. The initial gas temperature is 350℃.

[0079] This embodiment provides a method for enhancing the heat and mass transfer rate of oil extraction using horizontal well groups, which includes the following specific steps:

[0080] (1) The design includes a horizontal well group consisting of one injection well and four production wells. The injection well is heated by an electric heater, and then the injected hot CO2 gas is used for secondary heating.

[0081] (2) Determine whether horizontal or vertical cracks that meet the requirements have been generated in the well group;

[0082] (3) Close the production well, open the injection well, and simultaneously turn on the electric heater of the injection well to inject hot CO2 gas;

[0083] (4) After heating is complete, open the production well and collect the discharged gas;

[0084] (5) When the daily gas production of the production well is less than 200m³ 3 When / d, production is stopped and the heating process of step (3) is restarted. This cycle is repeated to achieve enhanced heat and mass transfer heating.

[0085] In step (1), the horizontal well group consists of one injection well and four production wells. The horizontal well group employs volumetric fracturing. Hot CO2 gas is injected at a temperature of 350°C.

[0086] In step (1), the power of the electric heater per meter of heating section is 2000W, and the surface heating temperature of the electric heater is 350℃-500℃.

[0087] In step (2), the vertical crack has a length of 0.5m; the main horizontal crack has a length of 1m.

[0088] In step (3), when the CO2 injection pressure reaches 20 MPa and the injection speed reaches 500 m / s... 3 When / d, close the injection well and stop gas injection, while the electric heater continues to work and the well is shut off for 10 days.

[0089] In step (4), the exhaust gas rate is controlled to 1000 m / s. 3 / d and below.

[0090] The horizontal wellbore method used in this embodiment to enhance heat and mass transfer rate achieved efficient temperature rise in the reservoir, with a reservoir volume exceeding 300°C of 1536.6 m³. 3 (Single electric heating: 371.5m) 3 ).

[0091] As can be seen from the above embodiments, the oil extraction method for enhancing heat and mass transfer rate in horizontal well groups of the present invention achieves at least the following beneficial effects:

[0092] 1. Compared with conventional methods that use numerical simulation to determine heat and mass transfer parameters, this invention employs a combination of laboratory experiments and numerical simulation, considering fracture type and gas injection rate, to determine heating efficiency parameters. This approach can illustrate the temperature variation characteristics of the reservoir and obtain optimal implementation parameters.

[0093] 2. This invention uses heated triaxial rock mechanics experiments and X-ray diffraction analysis to determine the injection pressure and temperature of CO2 by measuring the changes in clay mineral composition with temperature. Compared with conventional general injection, this invention can effectively achieve reservoir thermal cracking and high-temperature and high-pressure reservoir stimulation.

[0094] 3. This invention employs a circulating injection of hot gas, achieving a perfect combination of efficient heating and increased production. It can leverage different functions and advantages to maximize the development effect of supercritical steam injection.

[0095] 4. This invention uses the residual oil saturation obtained from nano-CT digital core testing to determine the gas injection volume, which can effectively determine the minimum and maximum gas injection volumes, achieving the best results while avoiding excessive gas waste.

[0096] 5. This invention proposes a method to improve reservoir heating efficiency by using hot gas-assisted electric heating, which can enhance the heat and mass transfer rate to a greater extent compared with conventional electric heating methods.

[0097] It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions, and although a logical order is shown in the flowchart, in some cases the steps shown or described may be executed in a different order than that shown here.

[0098] Based on the same inventive concept, embodiments of the present invention also provide an oil extraction apparatus for enhancing the thermal mass transfer rate of horizontal well groups, which can be used to implement the oil extraction method for enhancing the thermal mass transfer rate of horizontal well groups described in the above embodiments, as described in the following embodiments. Since the principle of solving the problem with the oil extraction apparatus for enhancing the thermal mass transfer rate of horizontal well groups is similar to that of the oil extraction method for enhancing the thermal mass transfer rate of horizontal well groups, embodiments of the oil extraction apparatus for enhancing the thermal mass transfer rate of horizontal well groups can refer to embodiments of the oil extraction method for enhancing the thermal mass transfer rate of horizontal well groups, and repeated descriptions will not be repeated. As used below, the terms "unit" or "module" can refer to a combination of software and / or hardware that performs a predetermined function. Although the apparatus described in the following embodiments is preferably implemented in software, hardware implementation, or a combination of software and hardware, is also possible and contemplated.

[0099] Figure 3 This is a first structural block diagram of an oil extraction device for enhancing heat and mass transfer rate in a horizontal well group according to an embodiment of the present invention, as shown below. Figure 3 As shown, in one embodiment of the present invention, the oil extraction apparatus for enhancing the heat and mass transfer rate of horizontal well groups includes:

[0100] Heating control unit 1 is used to start heating when preset heating conditions are met. At this time, the production well in the horizontal well group is closed, the injection well in the horizontal well group is opened, the electric heater installed in the injection well is turned on, and hot gas is injected into the injection well. The heating conditions include: the daily gas production of the production well is less than the preset production value and the horizontal well group produces horizontal and / or vertical cracks that meet the requirements.

[0101] Production control unit 2 is used to close the injection well and open the production well to begin oil extraction after heating is completed.

[0102] Figure 4 This is a second structural block diagram of an oil extraction device for enhancing heat and mass transfer rate in a horizontal well group according to an embodiment of the present invention, as shown below. Figure 4 As shown, in one embodiment of the present invention, the oil extraction apparatus for enhancing heat and mass transfer rate in horizontal well groups further includes:

[0103] The exhaust control unit 3 is used to control the rate of exhaust gas to below a preset rate and to collect the exhaust gas during oil extraction.

[0104] In one embodiment of the present invention, the heating control unit is further configured to, during the heating process, close the injection well and stop injecting the hot gas when the injection pressure of the hot gas reaches a preset pressure value and the injection speed of the hot gas drops below a preset injection speed, so that the electric heater continues to work and simultaneously perform a preset time of well simmering.

[0105] To achieve the above objectives, according to another aspect of this application, a computer device is also provided. For example... Figure 5 As shown, the computer device includes a memory, a processor, a communication interface, and a communication bus. The memory stores a computer program that can run on the processor. When the processor executes the computer program, it implements the steps in the method of the above embodiments.

[0106] The processor can be a central processing unit (CPU). The processor can also be other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, or combinations of the above types of chips.

[0107] Memory, as a non-transitory computer-readable storage medium, can be used to store non-transitory software programs, non-transitory computer-executable programs, and units, such as the program units corresponding to the above-described method embodiments of the present invention. The processor executes various functional applications and data processing of the processor by running the non-transitory software programs, instructions, and modules stored in the memory, thereby implementing the methods described in the above-described method embodiments.

[0108] The memory may include a program storage area and a data storage area. The program storage area may store the operating system and applications required for at least one function; the data storage area may store data created by the processor, etc. Furthermore, the memory may include high-speed random access memory and non-transitory memory, such as at least one disk storage device, flash memory device, or other non-transitory solid-state storage device. In some embodiments, the memory may optionally include memory remotely located relative to the processor, which can be connected to the processor via a network. Examples of such networks include, but are not limited to, the Internet, corporate intranets, local area networks, mobile communication networks, and combinations thereof.

[0109] The one or more units are stored in the memory and, when executed by the processor, perform the methods described in the above embodiments.

[0110] The specific details of the aforementioned computer equipment can be understood by referring to the relevant descriptions and effects in the above embodiments, and will not be repeated here.

[0111] To achieve the above objectives, according to another aspect of this application, a computer-readable storage medium is also provided, which stores a computer program that, when executed in a computer processor, implements the steps in the above-described method for enhancing the thermal and mass transfer rate of horizontal well groups in oil extraction. Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The program can be stored in a computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. The storage medium can be a magnetic disk, optical disk, read-only memory (ROM), random access memory (RAM), flash memory, hard disk drive (HDD), or solid-state drive (SSD), etc.; the storage medium may also include combinations of the above types of memory.

[0112] To achieve the above objectives, according to another aspect of this application, a computer program product is also provided, comprising a computer program / instructions that, when executed by a processor, implement the steps of the above-described oil extraction method for enhancing the thermal and mass transfer rate of horizontal well groups.

[0113] Obviously, those skilled in the art will understand that the modules or steps of the present invention described above can be implemented using general-purpose computing devices. They can be centralized on a single computing device or distributed across a network of multiple computing devices. Optionally, they can be implemented using computer-executable program code, thereby storing them in a storage device for execution by a computing device, or fabricating them separately as individual integrated circuit modules, or fabricating multiple modules or steps as a single integrated circuit module. Thus, the present invention is not limited to any particular hardware and software combination.

[0114] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for oil extraction using horizontal well groups to enhance heat and mass transfer rate, characterized in that, include: When the preset heating conditions are met, heating begins. At this time, the production well in the horizontal well group is closed, the injection well in the horizontal well group is opened, the electric heater installed in the injection well is turned on, and hot gas is injected into the injection well. The heating conditions include: the daily gas production of the production well is less than the preset production value and the horizontal well group produces horizontal and / or vertical fractures that meet the requirements. After heating is complete, the injection well is closed and the production well is opened to begin oil extraction.

2. The oil extraction method for enhancing heat and mass transfer rate in horizontal well groups according to claim 1, characterized in that, Also includes: During oil extraction, the rate of gas discharge is controlled to be below a preset rate, and the discharged gas is collected.

3. The oil extraction method for enhancing heat and mass transfer rate in horizontal well groups according to claim 1, characterized in that, The horizontal well group uses volumetric fracturing to stimulate the reservoir.

4. The oil extraction method for enhancing heat and mass transfer rate in horizontal well groups according to claim 1, characterized in that, The hot gas is carbon dioxide gas with a temperature not lower than 300°C.

5. The oil extraction method for enhancing heat and mass transfer rate in horizontal well groups according to claim 1, characterized in that, The heating section of the electric heater is located within the reservoir, the power of each meter of the heating section of the electric heater is 100W to 2000W, and the surface heating temperature of the electric heater is 350℃ to 500℃.

6. The oil extraction method for enhancing heat and mass transfer rate in horizontal well groups according to claim 1, characterized in that, The requirement for vertical fractures is that the fracture height does not exceed the thickness of the oil layer; the requirement for horizontal fractures is that zipper-type cross fracturing is used, and the distance between the main fractures does not exceed 2 / 3 of the well spacing.

7. The oil extraction method for enhancing heat and mass transfer rate in horizontal well groups according to claim 1, characterized in that, Also includes: During the heating process, when the injection pressure of the hot gas reaches a preset pressure value and the injection speed of the hot gas drops below the preset injection speed, the injection well is closed, the injection of the hot gas is stopped, and the electric heater continues to work while the well is shut down for a preset duration.

8. An oil extraction device for enhancing heat and mass transfer rate in horizontal well groups, characterized in that, include: A heating control unit is used to start heating when preset heating conditions are met. At this time, the production well in the horizontal well group is closed, the injection well in the horizontal well group is opened, the electric heater installed in the injection well is turned on, and hot gas is injected into the injection well. The heating conditions include: the daily gas production of the production well is less than the preset production value and the horizontal well group produces horizontal and / or vertical cracks that meet the requirements. The production control unit is used to close the injection well and open the production well to begin oil extraction after heating is complete.

9. The oil extraction apparatus for enhancing heat and mass transfer rate in horizontal well groups according to claim 8, characterized in that, Also includes: An exhaust control unit is used to control the rate of exhaust gas to below a preset rate and to collect the exhaust gas during oil extraction.

10. The oil extraction apparatus for enhancing heat and mass transfer rate in horizontal well groups according to claim 8, characterized in that, The heating control unit is also used to, during the heating process, when the injection pressure of the hot gas reaches a preset pressure value and the injection speed of the hot gas drops below a preset injection speed, close the injection well, stop injecting the hot gas, and allow the electric heater to continue working while simultaneously performing a preset period of well simmering.

11. A computer device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the steps of the method according to any one of claims 1 to 7.

12. A computer-readable storage medium having a computer program / instructions stored thereon, characterized in that, When the computer program / instructions are executed by the processor, they implement the steps of the method according to any one of claims 1 to 7.

13. A computer program product comprising a computer program / instructions, characterized in that, When the computer program / instructions are executed by the processor, they implement the steps of the method according to any one of claims 1 to 7.

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