Heavy oil heat-flow coupling development experimental device and method based on microwave-assisted gravity drainage

Abstract

The invention provides a heavy oil thermal-flow coupling development experimental device and method based on microwave-assisted gravity drainage, and belongs to the field of oil-gas field development. The experimental device comprises a three-dimensional oil reservoir simulation system, a microwave-assisted heating system, a horizontal well injection-production regulation and control system and a multi-field monitoring system; the microwave auxiliary heating system comprises a microwave generation regulation and control system, a microwave transmission system and a shaft integrated microwave radiator, the microwave generation regulation and control system comprises an industrial grade microwave generator, a power regulator and a PLC, and the microwave transmission system comprises a microwave coaxial cable and a microwave waveguide tube bundle; and the microwave generator is continuously connected with the microwave waveguide tube bundle and the shaft integrated microwave radiator. According to the heavy oil thermal-flow coupling development experimental device and method based on microwave-assisted gravity oil drainage, the technical problems that an existing deep heavy oil thermal recovery experimental device cannot reproduce a'thermal-flow-force 'multi-field coupling environment, the microwave heating adaptability is poor, and the experimental scale and the field deviation is large are solved. The heavy oil thermal-flow coupling development experimental device and method based on microwave-assisted gravity oil drainage solve the technical problems that an existing deep heavy oil thermal recovery experimental device cannot reproduce the'thermal-flow-force' multi-field coupling environment.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of oil and gas field development, and in particular to a heavy oil thermal-flow coupling development experimental device and method based on microwave-assisted gravity drainage. BACKGROUND

[0002] At present, with the increasing depletion of shallow heavy oil resources, the demand for heavy oil in society continues to remain at a high level. In order to meet this demand, the oil and gas development field gradually extends its tentacles to deep heavy oil resources. Globally, efficient heavy oil development technologies such as steam huff and puff, steam / solvent assisted gravity drainage (SAGD) and gas assisted gravity drainage (GAGD) have become the mainstream means for current heavy oil development through reducing heavy oil viscosity and improving its flowability. Among them, gravity drainage technology relies on the core mechanism of "heating viscosity reduction-gravity driving-horizontal well production", which has achieved remarkable results in the commercial development of shallow heavy oil reservoirs, with recovery efficiency exceeding 30%.

[0003] However, when these technologies are applied to deep heavy oil development, they face many challenges. Specifically, in the SAGD technology, the injected high-temperature steam or heated gas will lose a lot of heat to the surrounding rock through the wellbore and the formation during long-distance migration, resulting in rapid decrease of the steam dryness at the bottom of the well, and thus it is difficult to achieve large-scale thermal viscosity reduction of heavy oil. On the other hand, the CO2 or N2 gas used in GAGD technology has significantly improved solubility under high pressure, and part of the gas dissolved in the formation water loses its displacement ability, while the low thermal conductivity of the gas makes the thermal efficiency much lower than that of steam, with limited heating range.

[0004] In view of the above problems, microwave-assisted heating technology shows its unique advantages. This technology can efficiently and accurately transfer heat energy to the target deep heavy oil reservoir, providing a new idea for solving the problem of deep heavy oil development. At present, the heavy oil thermal recovery experimental devices commonly used in laboratories mainly focus on the simulation of single thermal field or flow field, and it is difficult to reproduce the complex environment of "thermal-flow-force" multi-field coupling in deep reservoirs. This limitation restricts the research and application of new technologies such as microwave-assisted gravity drainage. In particular, the existing devices are mostly designed based on traditional thermal recovery technologies, and lack of adaptability to new heating methods such as microwaves. Although some thermal coupling devices can apply confining pressure to simulate ground stress, they do not fully consider the dynamic interaction between fluid flow and heat transfer in the reservoir pores, resulting in the inability to accurately measure key parameters such as heavy oil viscosity change, fluid seepage velocity, temperature field distribution under microwave heating.

[0005] In addition, the experimental scale of the existing experimental device is mostly centimeter level, which is difficult to reflect the propagation law of microwave energy, thermal cavity expansion characteristics and macro effect of gravity drainage in actual oil reservoir. This leads to a large deviation between experimental data and field application, which cannot provide reliable experimental support for parameter optimization of microwave assisted gravity drainage technology. Therefore, it is particularly urgent and important to develop a device and method which can realize thermal-flow coupling environment simulation of deep heavy oil reservoir, adapt to microwave heating technology and have macro scale experimental capability. SUMMARY

[0006] The purpose of the present application is to provide a heavy oil thermal-flow coupling development experimental device and method based on microwave assisted gravity drainage, which solves the technical problems that the existing deep heavy oil thermal recovery experimental device cannot reproduce the "thermal-flow-force" multi-field coupling environment, the microwave heating adaptability is poor and the experimental scale deviates greatly from the field.

[0007] To achieve the above purpose, the present application provides a heavy oil thermal-flow coupling development experimental device based on microwave assisted gravity drainage, which comprises a three-dimensional oil reservoir simulation system, a microwave assisted heating system, a horizontal well injection-production control system and a multi-field monitoring system, The microwave assisted heating system comprises a microwave generation control system, a microwave transmission system and a wellbore integrated microwave radiator, the microwave generation control system comprises an industrial microwave generator, a power regulator and a PLC controller, the microwave transmission system comprises a microwave coaxial cable and a microwave waveguide bundle, and the microwave generator is connected in series with the microwave waveguide bundle and the wellbore integrated microwave radiator; The horizontal well injection-production control system comprises an injection supply system, a metering and control system and a double horizontal well pattern system, the double horizontal well pattern system comprises an upper injection-production wellbore and a lower production wellbore, the upper injection-production wellbore and the lower production well are arranged at a target design distance apart along the height direction of the three-dimensional sand filling model, and the well site fixing mechanism adopts a threaded pin tightening structure and a through hole embedding and sealing of the model wrapping shell; The wellbore integrated microwave radiator comprises an outer conductor, an inner conductor and a dielectric filling part, the outer conductor has a microwave radiation port with a wave permeable medium on the side surface, the wellbore integrated microwave radiator is connected with the waveguide bundle and the short circuit cover at both ends respectively, and the wellbore integrated microwave radiator is a double conductor structure coaxial with the double horizontal wellbore.

[0008] Preferably, the three-dimensional oil reservoir simulation system comprises a three-dimensional microwave adaptation wrapping shell, a sealing and heat preservation system, a trap pressure maintaining system and a heavy oil porous medium filler, and the heavy oil porous medium filler is filled in the three-dimensional microwave adaptation wrapping shell; The three-dimensional microwave adaptation wrapping shell is made of a stainless steel composite plate containing a metal matrix and a heat insulation core layer, and a rotary adjusting mechanism is installed on the outer vertical surface of the stainless steel composite plate outside the three-dimensional microwave adaptation wrapping shell; The sealing and heat preservation system comprises a composite heat insulation layer, a microwave shielding layer and a sealing and anti-infiltration structure. The composite heat insulation layer comprises, from inside to outside, a high-temperature resistant ceramic fiber layer, an aerogel felt layer and a silica heat preservation coating. The microwave shielding layer comprises a tinned copper mesh sandwiched between the ceramic fiber layer and the aerogel felt layer. The sealing and anti-infiltration structure comprises a fluororubber sealing ring at the joint of the three-dimensional microwave adaptive wrapping shell and an annular recess thereof. The closed pressure maintaining system comprises a single-cylinder plunger type confining pressure pump, a hydraulic loading part, a pressure buffer tank and a pressure feedback control module. The output end of the single-cylinder plunger type confining pressure pump is connected to the hydraulic loading part through a high-pressure pipeline. The hydraulic loading part is in the form of an annular structure and is embedded around a metal frame outside the wrapping shell of the three-dimensional sand filling model. The pressure buffer tank is in communication with the inside of the wrapping shell of the three-dimensional sand filling model through a pipeline. The pressure feedback control module comprises a pressure sensor and a PLC controller. The pressure sensor is installed inside the model and at the outlet of the pressure buffer tank.

[0009] Preferably, the injection supply system comprises a double-cylinder plunger type displacement pump, a liquid supply intermediate container, a displacement gas cylinder and a gas flow control meter. The output end of the double-cylinder plunger type displacement pump is connected to the liquid supply intermediate container through a liquid distribution three-way valve. The output end of the displacement gas cylinder is connected to the gas flow control meter. The output ends of the liquid supply intermediate container and the gas flow control meter are connected to a six-way valve and an upper injection wellbore of the double horizontal well pattern system, respectively. The metering, measuring and control system comprises a measuring cylinder connected to the outlet of the six-way valve and an electronic balance matched with the lower end of the measuring cylinder.

[0010] Preferably, the multi-field monitoring system comprises a temperature field monitoring system, a pressure field monitoring system, a saturation field monitoring system and a data acquisition unit. The temperature field monitoring system comprises a distributed temperature sensitive optical fiber and a temperature detection array. The temperature sensitive optical fiber is laid in a grid shape inside the three-dimensional sand filling model. The temperature detection array is uniformly arranged along the axes of the upper injection wellbore, the lower production wellbore and the inner wall of the three-dimensional sand filling model. The pressure field monitoring system comprises a pressure detection array and an electronic pressure gauge. The pressure detection array is embedded in the porous medium inside the three-dimensional sand filling model. The electronic pressure gauge is installed at the first six-way valve outlet of the injection supply system, the second six-way valve inlet and the front end of the back pressure valve of the lower production wellbore.

[0011] Preferably, the wellbore integrated microwave radiator is coaxially embedded inside the upper horizontal injection wellbore of the wrapping shell of the three-dimensional sand filling model. The wellbore integrated microwave radiator is fixed and sealed to the inner wall of the wellbore through flanges at both ends. One end of the microwave waveguide bundle penetrates the tinned copper mesh microwave shielding layer of the sealing and heat preservation system outside the wrapping shell of the three-dimensional model, is connected to the microwave radiator through a metal sealing joint, and the other end of the microwave waveguide bundle is connected to the external microwave generation and control system through a microwave coaxial cable.

[0012] The experimental method for developing thickened oil based on microwave-assisted gravity drainage and heat-flow coupling comprises the following steps: S1, constructing a physical model of deep thickened oil reservoir: according to the reservoir porosity, permeability, burial depth characteristics and crude oil properties, a high-pressure thickened oil reservoir is constructed, a microwave-assisted heating system and a double horizontal well network system are arranged in the reservoir, a saturated thickened oil porous medium is prepared and filled in a three-dimensional microwave adaptive wrapping shell, and after adjusting to the target porosity, thickened oil is injected to a stable oil production state; S2, microwave-assisted heating and injection-production system debugging: start the microwave-assisted heating system, set the heating mode and initial power through the PLC controller, control the injection fluid through the injection supply system to supplement the energy, test the microwave-assisted heating and wellbore connection ability, check the sealing property of each system connection and the equipment running state; S3, microwave-assisted drainage and multi-field parameter acquisition: start the injection-production, pressure regulation system and microwave-assisted heating system, use the multi-field monitoring system to synchronously collect data, including temperature, pressure data and oil saturation data through pressure, conductivity and heat conduction inversion, sample and record at fixed time intervals; S4, experimental parameter optimization and data verification: dynamically adjust the experimental parameters according to the monitoring results of S3, if the temperature of a certain area is lower than the critical value of thickened oil viscosity reduction, increase the power of the corresponding microwave radiator through the power regulator, or increase the injection pressure to increase the liquid production; when the model liquid production is continuously low, the experiment is terminated; calculate the experimental oil production and the oil production based on the saturation, if the deviation is ≤5%, the data meets the law of conservation of mass, which can be used to analyze the influence law of microwave power and injection parameters on heat-flow coupling effect, and to carry out error analysis and reliability evaluation on experimental data.

[0013] Preferably, the pressure field saturation inversion expression is: ; wherein, is a pressure conductivity coefficient, is a pressure conductivity undetermined coefficient, is the permeability of the porous medium, is the porosity, is the viscosity, is the fluid comprehensive compressibility coefficient, is the oil saturation; ; wherein, is a conductivity coefficient, is a conductivity undetermined coefficient, is the fluid resistivity, is the porosity, is the oil saturation; ; wherein, k is the thermal conductivity, k is the thermal conductivity of the rock, oil phase and water phase, k is the thermal conductivity, So is the oil saturation.

[0014] Therefore, the present application adopts the above-mentioned heavy oil thermal-flow coupling development experimental device and method based on microwave-assisted gravity drainage, and the technical effects are as follows: 1. Adapt to the development needs of deep heavy oil: combining microwave-assisted heating technology and gravity drainage technology, through a large-size three-dimensional porous medium model as an experimental carrier, combined with a wellbore integrated microwave radiator and a dual horizontal well structure, directional transmission of microwave energy is realized, energy loss in the process of thermal recovery of deep heavy oil is reduced, and the development needs of deep heavy oil are accurately adapted.

[0015] 2. Reliable data are ensured by a multi-field monitoring system: equipped with a pressure-conducting, electricity-conducting and heat-conducting multi-physical field monitoring system, combined with a clear saturation inversion formula, the dynamic changes of key parameters such as temperature, pressure and saturation can be captured simultaneously, ensuring that the measurement error is controlled within ≤5%, and providing accurate data support for parameter adjustment of microwave-assisted gravity drainage technology.

[0016] 3. Macro-scale experimental capability improves technology conversion efficiency: the injection-production system can realize injection of multiple media such as formation water, solvent and displacement gas, the microwave system supports power adjustment and heating mode switching, and is matched with a trap pressure maintaining system and a sealed heat preservation system to reproduce the deep reservoir environment, and the experimental data can directly guide the field well pattern deployment and parameter setting. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 It is a logic flow chart of the heavy oil thermal-flow coupling development experimental device and method based on microwave-assisted gravity drainage technology of the present application; Figure 2 It is a device connection schematic diagram of the heavy oil thermal-flow coupling development experiment based on microwave-assisted gravity drainage technology of the present application; Figure 3 It is a device design schematic diagram with microwave-assisted heating wellbore based on microwave-assisted gravity drainage technology in the present application; Figure 4 It is a logic schematic diagram for improving the development effect of heavy oil based on microwave-assisted gravity drainage technology in the present application; Figure 5 It is an oil saturation distribution field diagram generated by using steam-assisted gravity drainage technology in Example 1; Figure 6 It is an oil saturation distribution field diagram generated by using microwave-assisted gravity drainage technology in Example 1.

[0018] REFERENCE NUMERALS 10. Dual-cylinder plunger displacement pump; 11. Three-way valve for liquid distribution; 12. Intermediate liquid supply container; 13. Displacement gas cylinder; 14. Gas flow controller; 15. Six-way valve; 16. Back pressure valve; 17. Measuring cylinder; 18. Electronic balance; 19. Single-cylinder plunger confining pressure pump; 20. Three-dimensional microwave adapter enclosure; 21. PLC controller; 22. Wellbore integrated microwave radiator; 23. Upper injection wellbore; 24. Lower production wellbore; 25. Rotary controller; 30. Data processing computer; 31. Temperature detection array; 32. Pressure detection array; 33. Potential detection array; 201. Perforated wellbore; 202. Horizontal well heel microwave fixing device; 204. Outer conductor inner copper tube; 205. Polytetrachloroethylene electrode; 206. Microwave radiating port; 207. Flexible microwave conduit bundle; 208. Horizontal well toe fixing device. Detailed Implementation

[0019] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0020] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains.

[0021] Example 1 like Figure 1 As shown, this invention provides a thermal-fluid coupled development experimental device and method for heavy oil based on microwave-assisted gravity drainage technology. It is based on a reservoir simulation system and its associated reservoir development system, with microwave-assisted gravity drainage technology for the development of deep heavy oil as the core, and uses multi-field calibration of heavy oil saturation as an extension to form a comprehensive development evaluation method for deep heavy oil.

[0022] like Figures 2-3 As shown, the device includes a reservoir simulation development system, a microwave-assisted heating system, a horizontal well injection and production control system, and a multi-field monitoring system. Each system is connected in coordination through pipelines and data lines to realize the simulation of thermal-fluid coupling environment and parameter monitoring during the development simulation of deep heavy oil reservoirs under microwave-assisted gravity drainage.

[0023] The three-dimensional reservoir simulation system includes a three-dimensional microwave-adaptive encapsulation shell 20, a sealing and insulation system, a trapping and pressure-maintaining system, and a porous medium filling material for heavy oil. The three-dimensional microwave-adaptive encapsulation shell 20 is made of a stainless steel composite plate comprising a metal matrix and an insulating core layer. A rotation controller 25 is installed on the outer surface of the stainless steel composite plate surrounding the shell to construct heavy oil reservoirs at different dip angles. The three-dimensional microwave-adaptive encapsulation shell 20 is filled with a porous medium structure with rock particles as the framework and clay minerals as the cementing agent. In this embodiment, 40-mesh quartz sand was selected as the rock skeleton, and a 1:1 mixture of 160-mesh montmorillonite and kaolinite powder was selected as the clay mineral interstitial material. The clay minerals adhered to the surface of the quartz sand by means of an ultrasonic oscillating suspender (400W, 30kHz) and NaHCO3 solution. After the mixed particles were oscillated for 45 minutes and dried at 80℃ for 4 hours, they were soaked in simulated heavy oil with a viscosity of 7500 mPa·s at 50℃ and heated and stirred at 130℃ for 2.5 hours to ensure full adsorption. The mixture was filled into the three-dimensional microwave-adaptive encapsulation shell 20 by a layered compaction method, with each layer being 6 cm thick. The layers were compacted by a 10MPa hydraulic compactor to stabilize the porosity at 0.32 and the permeability at 1200 mD, matching the physical properties of the target deep oil reservoir. A deep, single-layer heavy oil reservoir with a burial depth of 2000 meters and a formation pressure of 20 MPa was simulated. Perforated completion was used in conjunction with a dual horizontal well network. Development simulation experiments were conducted using microwave-assisted hot water supplementation gravity drainage (experimental group) and steam-assisted gravity drainage (control group). By comparing the oil production efficiency, changes in oil saturation, and thermal utilization efficiency of the two development methods, the effectiveness of microwave-assisted gravity drainage technology in the development of deep heavy oil reservoirs was verified.

[0024] The sealing and insulation system includes a composite insulation layer, a microwave shielding layer, and a sealing and seepage-proof structure. The composite insulation layer, from the inside out, consists of a high-temperature resistant ceramic fiber layer, an aerogel felt layer, and a silica insulation coating, effectively blocking direct heat conduction between the model's interior and exterior. The microwave shielding layer includes a tin-plated copper mesh sandwiched between the ceramic fiber layer and the aerogel felt layer, preventing microwave energy loss and ensuring heating efficiency. The sealing and seepage-proof structure includes a fluororubber sealing ring at the shell joint and its associated annular groove, effectively preventing leakage of high-pressure fluids and the entry of external air, making it suitable for simulating high-pressure trap conditions in deep heavy oil reservoirs. The trap pressure-maintaining system consists of a single-cylinder plunger-type confining pressure pump 19, a hydraulic loading unit, a pressure buffer tank, and a pressure feedback control module. A single-cylinder plunger-type confining pressure pump 19 injects hydraulic oil into the annular hydraulic loading section (embedded in the outer metal frame of the enclosure shell) to apply a confining pressure of 20MPa to simulate ground stress; the pressure buffer tank is pre-filled with 20MPa nitrogen and connected to the inside of the enclosure shell to compensate for pressure fluctuations; the pressure sensor monitors the pressure inside the model in real time, and the confining pressure pump and back pressure valve 16 are linked through the PLC controller 21 to ensure that the pressure fluctuation is less than 0.5MPa, thus reproducing the deep reservoir trap environment.

[0025] The horizontal well network injection-production control system includes an injection supply system, a metering and control system, and a wellbore configuration system. The injection supply system includes a dual-cylinder plunger displacement pump 10, a three-way valve 11, an intermediate supply container 12 (containing formation water and heavy oil), a displacement gas cylinder 13, a gas flow controller 14, and a six-way valve 15. The metering and control system includes a measuring cylinder 17 connected to the outlet of the six-way valve 15 and an electronic balance 18 at its lower end. In the control group, the displacement gas cylinder 13 can be replaced with a steam generator to re-inject steam into the simulated reservoir system. The fluid flow rate within the gas supply unit, such as the gas cylinder or steam generator, is recorded by the gas flow controller 14. Each supply unit is connected to the upper injection-displacement wellbore 23 via the six-way valve 15.

[0026] The wellbore system is designed based on gravity drainage logic and employs a perforated completion method. The upper injection wellbore 23 and the lower production wellbore 24 are arranged at 20cm intervals along the height of the casing. The well location fixing mechanism is a threaded fastening structure that fits tightly into the through-hole within the casing, enabling material exchange between external fluids and the reservoir without leakage. Sand-proof springs are fitted on the outer wall of the wellbore to meet sand control requirements and prevent porous media particles from clogging the wellbore.

[0027] The microwave-assisted heating system includes a microwave generation and control system, a microwave transmission system, and a well-integrated microwave radiator 22. The microwave generation and control system includes an industrial-grade microwave generator, a power regulator, and a PLC controller 21. The microwave transmission system includes a microwave coaxial cable and a microwave waveguide bundle.

[0028] The microwave-assisted heating system (for the experimental group only) includes an industrial-grade microwave generator, a microwave waveguide bundle, and a wellbore-integrated microwave radiator 22. The radiator has a dual-conductor structure, with five sets of wellbore-integrated microwave radiators 22 arranged axially and coaxially embedded within the upper injection wellbore 23, sealed at both ends with flanges. One end of the waveguide bundle is connected to the radiator via a tin-plated copper mesh, and the other end is connected to the microwave generator via a coaxial cable, ensuring directional transmission of microwave energy to the reservoir. Specifically, within the wellbore equipped with microwave-assisted heating, a perforated wellbore 201 is drilled in the horizontal wellbore to facilitate fluid communication. A horizontal wellbore-end microwave fixing device 202 is welded to the periphery of the wellbore at the wellhead to fix the wellbore-integrated microwave radiator 22. This radiator consists of an outer conductor and an inner copper tube 204 forming the main structure, surrounded by a polytetrafluoroethylene (PTFE) electrode 205 to facilitate the transmission of electrical energy around the wellbore and to generate heat through resistance to heat the heavy oil around the wellbore. Precise microwave radiation is achieved through the microwave radiation port 206 on the flexible microwave conduit bundle 207, and the overall fixation is finally completed by the horizontal well toe fixing device 208.

[0029] Three points need to be noted when arranging the microwave radiator with the upper injection well: First, ensure that the microwave radiator is completely coaxial with the upper injection well to avoid misalignment between the radiator and the well screen, which would prevent the microwave energy from being effectively radiated to the porous medium. Second, the length of the microwave radiator should match the length of the upper horizontal steam injection well to prevent obstruction of microwave transmission. Third, the vertical distance between the lower production well 24 and the upper injection well should be greater than the effective heating radius of the microwave to avoid direct heating of the fluid in the production well by the microwave, which would affect the monitoring of production parameters.

[0030] The multi-field monitoring system is applicable to both sets of experiments: temperature field monitoring uses a distributed temperature-sensitive optical fiber + K-type thermocouple as a temperature detection array 31; pressure field monitoring uses a 48-unit pressure detection array 32 + 16 electronic pressure gauges (installed near the injection and production ends) as a pressure detection array; and conductivity field monitoring uses uniformly inserted electrodes to measure resistivity at various locations as a potential detection array 33. Saturation field monitoring integrates pressure conduction, conductivity, and thermal conduction subsystems, transmitting data to a data processing computer 30, and dynamically generating field distribution maps.

[0031] Based on the three-dimensional reservoir simulation system shared by the two sets of experiments, according to Figure 2 Connect the various devices: Install a dual horizontal well and a pressure / potential / temperature detection array 31 inside the enclosure, lay a bottom plate heating device, and seal and insulate the walls; after filling with oil sand, use a single-cylinder plunger-type confining pressure pump 19 to apply 20MPa confining pressure, and use a double-cylinder plunger-type displacement pump 1010 to saturate heavy oil until stable oil production is achieved at the outlet. Measure the saturated oil mass using an electronic balance 18, which is 36582g; age at 85℃ for 144h to ensure pressure balance, at which point the initial oil saturation is 0.81.

[0032] In the experimental control group, steam-assisted gravity drainage was used to inject high-temperature steam into a simulated deep heavy oil reservoir through a horizontal well network using a steam generator. The multi-field monitoring system simultaneously collected data and formed various physical field maps: in the first 3 hours, an effective hot cavity with a radius of 12cm was formed around the injection wellbore; after 6 hours, the hot cavity expanded to 18cm, and the production wellbore began to produce oil stably; after 10 hours, the water content of the produced fluid exceeded 90%, and the experiment was stopped, with a cumulative oil production of 4826g.

[0033] like Figure 5 As shown, after the experiment, the oil saturation was inverted based on data such as pressure field, temperature field, and electrical field, and the final average oil saturation was 0.47, with a recovery rate of 42.0%. The deviation between the experimental oil production and the calculated oil production (4952g) was 2.5%≤5%, and the data conformed to the law of conservation of mass.

[0034] The expression for the inversion of pressure field saturation is: ; in, The pressure conductivity coefficient, All of these are undetermined coefficients for pressure conduction. For porous media permeability, Porosity Viscosity, The overall compressibility coefficient of the fluid. Oil saturation; ; in, The conductivity coefficient, The conductivity coefficient is undetermined. For fluid resistivity, Porosity Oil saturation; ; in, Thermal conductivity, The thermal conductivity of the rock, oil phase, and water phase are given. So represents porosity, and So represents oil saturation.

[0035] like Figure 4 As shown, in the experimental research group using microwave-assisted gravity oil drainage, a dual-cylinder plunger displacement pump 10 was used to inject hot water into a simulated deep heavy oil reservoir through a horizontal well network. The microwave generator was set to pulse heating mode, and the PLC controller 21 was linked to the temperature detection array 31. When the reservoir temperature was <80℃ (the critical value for viscosity reduction of heavy oil), the power was automatically increased. The back pressure valve 16 controlled the pressure at 20MPa, and the multi-field monitoring system collected data synchronously.

[0036] Microwave preheating for 30 minutes (reaching 80℃ in a 5cm area around the injection wellbore), followed by starting the displacement pump to inject hot water; a 14cm radius hot cavity is formed in the first 3 hours, and the hot cavity expands to 20cm after 6 hours, and the production wellbore begins to produce oil stably; the experiment is stopped after 10 hours when the water cut exceeds 90%, with a cumulative oil production of 5683g.

[0037] like Figure 6 As shown, after the experiment, the oil saturation was inverted based on data such as pressure field, temperature field, and electrical field, and the final average oil saturation was 0.38, with a recovery rate of 53.1%. The deviation between the experimental oil production and the calculated oil production (5817g) was 2.3%≤5%, indicating that the data was accurate.

[0038] Comparing the two experimental groups, the recovery rate of the experimental group with microwave-assisted gravity drainage (53.1%) was 11.1 percentage points higher than that of the control group with steam-assisted gravity drainage (42.0%), and the oil production rate was increased by 18.8%. The thermal efficiency of the experimental group (38.2% (microwave directional heating + hot water supplementation)) was significantly higher than that of the control group (25.6% (steam long-distance heat dissipation)). This proves that microwave-assisted hot water supplementation gravity drainage technology is more suitable for deep heavy oil development. The experiment yielded the optimal parameters such as microwave power and fluid injection rate, which can directly guide the deployment of well networks and the optimization of development parameters in the field.

[0039] Therefore, this invention employs the aforementioned experimental device and method for the thermal-fluid coupling development of heavy oil based on microwave-assisted gravity drainage. It integrates microwave-assisted heating and gravity drainage technologies, constructs a multi-field monitoring system, and achieves system synergy and macroscopic experimental capabilities. This provides an efficient and reliable technical solution for the development of deep heavy oil. The device uses a pressure- and temperature-resistant, microwave-shielded tin-plated and silica-based shell to construct a novel development technology suitable for heavy oil reservoirs under deep high-temperature and high-pressure conditions. This technology compensates for the insufficient heat transfer capacity of injected steam under high pressure, solves the problem of "overheating near the well while stagnation in distant wells," and guides the efficient tapping of potential during the physical simulation of microwave-assisted gravity drainage development of deep heavy oil.

[0040] 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 preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A device for the development of heavy oil by thermal-flow coupling based on microwave-assisted gravity drainage, characterized in that, The experimental device comprises a three-dimensional oil reservoir simulation system, a microwave-assisted heating system, a horizontal well injection-production control system and a multi-field monitoring system. The microwave-assisted heating system comprises a microwave generation control system, a microwave transmission system and a wellbore integrated microwave radiator, the microwave generation control system comprises an industrial microwave generator, a power regulator and a PLC controller, the microwave transmission system comprises a microwave coaxial cable and a microwave waveguide bundle, and the microwave generator is connected with the microwave waveguide bundle and the wellbore integrated microwave radiator. The horizontal well injection-production control system comprises an injection supply system, a metering control system and a double horizontal well network system, the double horizontal well network system comprises an upper injection-production wellbore and a lower production wellbore, the upper injection-production wellbore and the lower production wellbore are arranged at a target design distance apart along the height direction of a three-dimensional sand filling model, and a threaded pin structure is adopted for the well site fixing mechanism to be embedded and sealed with a through-hole wellbore of a model wrapping shell. The wellbore integrated microwave radiator comprises an outer conductor, an inner conductor and a dielectric filling part, the outer conductor has a microwave radiation port with a wave permeable medium on the side surface, the two ends of the wellbore integrated microwave radiator are connected with the waveguide bundle and a short-circuit cover respectively, and the wellbore integrated microwave radiator is a double-conductor structure coaxial with the double horizontal wellbore.

2. The experimental device for heavy oil thermal-flow coupling development based on microwave-assisted gravity drainage according to claim 1, characterized in that, The three-dimensional oil reservoir simulation system comprises a three-dimensional microwave adaptive wrapping shell, a sealing and heat preservation system, a trap pressure maintaining system and a heavy oil porous medium filler, and the heavy oil porous medium filler is filled in the three-dimensional microwave adaptive wrapping shell. The three-dimensional microwave adaptive wrapping shell is made of a stainless steel composite plate containing a metal base and a heat insulation core layer, and a rotary adjusting mechanism is installed on the outer vertical surface of the stainless steel composite plate of the three-dimensional microwave adaptive wrapping shell. The sealing and heat preservation system comprises a composite heat insulation layer, a microwave shielding layer and a sealing and anti-seepage structure, the composite heat insulation layer comprises, from inside to outside, a high-temperature resistant ceramic fiber layer, an aerogel felt layer and a silica heat preservation coating. The microwave shielding layer comprises a tinned copper mesh sandwiched between the ceramic fiber layer and the aerogel felt layer, and the sealing and anti-seepage structure comprises a fluororubber sealing ring at the joint of the three-dimensional microwave adaptive wrapping shell and an annular recess attached thereto. The trap pressure maintaining system comprises a single-cylinder plunger type confining pressure pump, a hydraulic loading part, a pressure buffer tank and a pressure feedback control module, the output end of the single-cylinder plunger type confining pressure pump is connected with the hydraulic loading part through a high-pressure pipeline, the hydraulic loading part is in the form of an annular structure and is embedded around a metal frame outside the three-dimensional sand filling model wrapping shell, the pressure buffer tank is connected with the inside of the three-dimensional sand filling model wrapping shell through a pipeline, and the pressure feedback control module comprises a pressure sensor and a PLC controller, and the pressure sensor is installed inside the model and at the outlet of the pressure buffer tank.

3. The experimental device for heavy oil thermal-flow coupling development based on microwave-assisted gravity drainage according to claim 1, characterized in that, The injection supply system comprises a double-cylinder plunger type displacement pump, a liquid supply intermediate container, a displacement gas cylinder and a gas flow control meter, the output end of the double-cylinder plunger type displacement pump is connected with the liquid supply intermediate container through a liquid distribution three-way valve, the output end of the displacement gas cylinder is connected with the gas flow control meter, and the output ends of the liquid supply intermediate container and the gas flow control meter are connected with a six-way valve and the upper injection-production wellbore of the double horizontal well network system respectively; The metering control system comprises a measuring cylinder connected with the outlet of the six-way valve and an electronic balance matched with the lower end of the measuring cylinder.

4. The experimental device for heavy oil thermal-flow coupling development based on microwave-assisted gravity drainage according to claim 1, characterized in that, The multi-field monitoring system comprises a temperature field monitoring system, a pressure field monitoring system, a saturation field monitoring system and a data acquisition unit, The temperature field monitoring system is composed of a distributed temperature-sensitive optical fiber and a temperature detection array, the temperature-sensitive optical fiber is laid in a grid shape in the inside of the three-dimensional sand filling model, and the temperature detection array is uniformly arranged along the upper injection-production wellbore, the lower production wellbore axis and the inner wall of the three-dimensional sand filling model. The pressure field monitoring system comprises a pressure detection array and an electronic pressure gauge, the pressure detection array is embedded in the porous medium in the three-dimensional sand filling model, and the electronic pressure gauge is installed at the outlet of the first six-way valve of the injection supply system, the inlet of the second six-way valve and the front end of the back pressure valve of the lower production wellbore.

5. The experimental device for heavy oil thermal-flow coupling development based on microwave-assisted gravity drainage according to claim 1, characterized in that, The wellbore integrated microwave radiator is coaxially embedded in the upper horizontal injection-production wellbore inside the wrapping shell of the three-dimensional sand filling model, the wellbore integrated microwave radiator is fixed and sealed to the wellbore inner wall through flanges at both ends, one end of the microwave waveguide bundle passes through the tinned copper mesh microwave shielding layer of the sealing and heat preservation system outside the three-dimensional model wrapping shell, is connected with the microwave radiator through a metal sealing joint, and the other end of the microwave waveguide bundle is connected with the external microwave generation and control system through a microwave coaxial cable.

6. The experimental method for the development of heavy oil by coupling heat and flow based on microwave-assisted gravity drainage, according to the experimental device for the development of heavy oil by coupling heat and flow based on microwave-assisted gravity drainage according to claims 1-5 is applied to the measurement, characterized in that, The method comprises the following steps: S1, constructing a deep heavy oil reservoir physical model: according to the reservoir porosity, permeability, burial depth characteristics and crude oil properties, a high-pressure heavy oil reservoir is constructed, a microwave-assisted heating system and a double-horizontal well pattern system are arranged in the reservoir, a porous medium saturated with heavy oil is prepared and filled in a three-dimensional microwave adaptive wrapping shell, and after adjusting to the target porosity, heavy oil is injected to a stable oil production state; S2, microwave-assisted heating and injection-production system debugging: start the microwave-assisted heating system, set the heating mode and initial power through the PLC controller, control the injection fluid through the injection supply system to supplement the energy, test the microwave-assisted heating and wellbore interconnection capacity, and check the sealing property of the system connection and the equipment operation state; S3, microwave-assisted oil discharge and multi-field parameter acquisition: start the injection-production, pressure control system and microwave-assisted heating system, synchronously acquire data by using the multi-field monitoring system, including temperature, pressure data and oil saturation data obtained by inversion through pressure guiding, electricity guiding and heat guiding, and sample and record at fixed time intervals; S4, experimental parameter optimization and data verification: dynamically adjust the experimental parameters according to the monitoring results of S3, if the temperature of a certain area is lower than the critical value of heavy oil viscosity reduction, the power of the corresponding microwave radiator is increased through the power regulator, or the injection pressure is increased to increase the liquid production; when the model liquid production is continuously low, the experiment is terminated; The experimental oil production and the oil production calculated based on the saturation are compared, if the deviation is less than or equal to 5%, the data meets the law of conservation of mass, and can be used to analyze the influence law of microwave power and injection parameters on the heat-flow coupling effect, and to perform error analysis and reliability evaluation on the experimental data.

7. The experimental method for developing heavy oil by heat-flow coupling based on microwave-assisted gravity drainage according to claim 6, characterized in that, The pressure field saturation inversion expression is: ； wherein, is the pressure conductivity, are pressure conductivity undetermined coefficients, is the porous medium permeability, is the porosity, is the viscosity, is the fluid overall compressibility, is the oil saturation; ； wherein, is the electrical conductivity, is the electrical conductivity, is the fluid resistivity, is the porosity, is the oil saturation; ； wherein is the thermal conductivity, is the thermal conductivity of the rock, oil phase and water phase, is the porosity, So is the oil saturation.

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