Injection-production fluid heat extraction experiment device and method under high-temperature and high-pressure conditions

Abstract

The invention discloses an injection and production fluid heat extraction experiment device and method under the high-temperature and high-pressure condition, and relates to the technical field of thermal oil extraction. The injection and production fluid heat extraction experiment device comprises a gas injection assembly, a hydraulic control system, a high-temperature and high-pressure system and a data acquisition and temperature control system; the high-temperature and high-pressure system comprises an injection pipe, a heat exchange pipe, an extraction pipe and a constant-temperature box, the hydraulic control system comprises a computer, a flow rate pump, a back-pressure valve and a condenser, and the gas injection assembly comprises a first gas cylinder, a second gas cylinder, a first three-way valve, a second three-way valve, a third three-way valve and a fourth three-way valve. The invention adopts the injection and production fluid heat extraction experiment device and method under the high-temperature and high-pressure conditions. Under the indoor condition, the comparison of the heat extraction capacity of the communication well and the branch well, the comparison of the heat extraction capacity of water and CO2, the influence of different heat exchange tube specifications on the heat extraction capacity and the heat extraction capacity comparison of the influence on the heat extraction capacity under the conditions of different temperatures, pressures and flow speeds can be realized.

Description

Technical Field

[0001] The invention relates to the technical field of thermal oil production, and in particular to an experimental device and method for extracting heat from injection and production fluid under high temperature and high pressure conditions. Background Art

[0002] Geothermal energy is a clean, stable, and widely distributed renewable energy source. It is also believed to be able to meet the growing energy needs of humans in the future. Of the total geothermal utilization in my country, shallow geothermal utilization combined with heat pumps accounts for about 60%, while traditional hydrothermal geothermal utilization for centralized heating accounts for less than 20%. Therefore, the current development and utilization of medium and deep geothermal energy urgently needs to solve the contradiction between people's growing demand for heat and sustainable green development of geothermal energy. It is necessary to develop a technology that is efficient in heat extraction and acceptable to the market that "extracts heat without taking water".

[0003] In a closed geothermal heat extraction system, the performance of the circulating fluid is a key factor in determining the efficient extraction and utilization of geothermal resources. Given that current evaluation methods mostly focus on a single dimension, it is difficult to fully capture the comprehensive performance of the circulating fluid in a complex and changeable geothermal environment. It is particularly urgent to build a comprehensive and systematic evaluation system. This evaluation system needs to comprehensively consider the thermophysical properties (such as specific heat capacity and thermal conductivity), fluidity (such as viscosity and flow properties), long-term operating stability, and compatibility with the environment of the circulating fluid to ensure that the selected circulating fluid can maximize the heat exchange efficiency of the geothermal system while meeting the requirements of clean and sustainable development. Summary of the invention

[0004] The purpose of the present invention is to provide an experimental device and method for heat extraction by injection and production of fluids under high temperature and high pressure conditions, to solve the problems raised in the above-mentioned background technology, and to use water and CO2 as comparison objects and as working fluids for circulating heat extraction, in order to accurately simulate the geothermal environment under different temperature and pressure conditions, and to deeply analyze and compare the production temperature performance of the two.

[0005] To achieve the above-mentioned purpose, the present invention provides an experimental device for heat extraction of fluid injection and production under high temperature and high pressure conditions, comprising a gas injection component, a hydraulic control system, a high temperature and high pressure system and a data acquisition and temperature control system, the data acquisition and temperature control system comprising a temperature control box and a temperature measuring probe, the high temperature and high pressure system comprising an injection pipe, a heat exchange pipe, a production pipe, and a constant temperature box, the hydraulic control system comprising a computer, a flow rate pump, a back pressure valve and a condenser, the gas injection component comprising a first gas cylinder, a second gas cylinder, a first three-way valve, a second three-way valve, a third three-way valve and a fourth three-way valve; The first gas cylinder and the second gas cylinder are both provided with pistons.

[0006] Preferably, the first three-way valve and the second three-way valve are respectively arranged at the upper and lower ends of the first gas cylinder, the third three-way valve and the fourth three-way valve are respectively arranged at the upper and lower ends of the second gas cylinder, the first three-way valve and the third three-way valve are connected through a pipeline 1, an outlet is arranged at the end of the pipeline 1, the second three-way valve and the fourth three-way valve are connected through a pipeline 2, and the end of the pipeline 2 is connected to the flow rate pump; The first three-way valve is provided with valve one and valve two, the second three-way valve is provided with valve three and valve four, the third three-way valve is provided with valve five and valve six, and the fourth three-way valve is provided with valve seven and valve eight.

[0007] Preferably, the thermostat includes a thermostat 1 and a thermostat 2, and both the thermostat 2 and the thermostat 1 are provided with resistance wires and a heat preservation layer; The heat exchange tubes include heat exchange tube 1 and heat exchange tube 2, and heat exchange tube 2 and heat exchange tube 1 are respectively arranged inside thermostatic box 2 and thermostatic box 1.

[0008] Preferably, four temperature measuring probes are provided, one end of each of the four temperature measuring probes is connected to a temperature control box, the other end of one of the temperature measuring probes is connected to a constant temperature box one, the other end of one of the temperature measuring probes is connected to a constant temperature box two, and the other ends of two of the temperature measuring probes are connected to the production pipe.

[0009] Preferably, one end of heat exchange tube one is connected to the hydraulic control system through an injection pipe, the other end of heat exchange tube one is connected to one end of heat exchange tube two through a connecting pipe, and the other end of heat exchange tube two is connected to the production pipe.

[0010] Preferably, a connecting valve 1 and a connecting valve 2 are respectively provided on the injection pipe and the connecting pipe.

[0011] Preferably, one end of heat exchange tube 1 and heat exchange tube 2 are connected to the hydraulic control system through the injection pipe, and the other end of heat exchange tube 2 and heat exchange tube 1 are connected to the production pipe.

[0012] Preferably, a connecting valve 1 and a connecting valve 2 are respectively provided at the connection point between the injection pipe and the heat exchange pipe 1, and at the connection point between the injection pipe and the heat exchange pipe 2.

[0013] A method for injecting and extracting fluid heat under high temperature and high pressure conditions comprises the following steps: Step S11, connect the experimental device in series, first connect the injection pipe and the extraction pipe to the heat exchange pipe 1 and the heat exchange pipe 2 respectively, then connect one end of the four temperature measuring probes to the temperature control box, and the other ends to the constant temperature box 1, the constant temperature box 2 and the extraction pipe respectively, and finally connect the outlet end of the constant temperature box 1 with the inlet end of the constant temperature box 2 through the connecting pipe, so that the injected fluid first flows through the heat exchange pipe 1 in the constant temperature box 1 and then enters the heat exchange pipe 2 in the constant temperature box 2. The size of the heat exchange pipe 1 is selected to be 6m long, and the length of the heat exchange pipe 2 is selected to be 1.5m; Step S12, turn on the power of the temperature control box, set the temperature of the thermostat box 1 to 15°C, and the temperature of the thermostat box 2 to 75°C according to the actual formation temperature of the study area. After setting, turn on the heating button until the temperature in the thermostat box 1 and the thermostat box 2 is heated to the set temperature and remains stable; Step S13, opening the connecting valve 1 and the connecting valve 2 to allow the injection fluid to be injected into the device; Step S14, open valve 1, valve 3, valve 6 and valve 7, close the remaining valves, remove pipeline 1, connect one end to the liquefied CO2 storage tank, and connect the other end to valve 2 and valve 6 respectively, inject CO2 into the first gas cylinder and the second gas cylinder, wait for a while until the pressure between the first gas cylinder and the second gas cylinder is equal, close valve 2, valve 3, valve 6 and valve 7, remove pipeline 1, restore to the initial state, and connect the outlet to the injection pipe; Step S15, opening valve 1, valve 4, valve 5 and valve 8, so as to inject water into the first gas cylinder and the second gas cylinder through the flow pump to push CO2 into the injection pipe; Step S16, opening the hydraulic control system, setting the injection pressure to 10 MPa and 20 MPa respectively, and starting to inject the fluid; Step S17: After a period of time, when the temperature displayed by the temperature control box is stable, observe and record the temperature data at the outlet of the extraction pipe; Step S18, set the temperature of the thermostat box 2 to 100°C and 150°C respectively, keep the temperature of the thermostat box 1 unchanged to carry out the experiment, and when the displayed temperature of the thermostat box is stable again, observe and record the temperature data at the outlet of the production pipe; Step S19, analyzing the temperature data, the magnitude of the temperature data reflects the heat extraction capacity when the injected working fluid is CO2.

[0014] Another method of injecting and extracting fluid heat under high temperature and high pressure conditions comprises the following steps: Step S21, connect the experimental device in parallel, connect the injection pipe to one end of the heat exchange tube 1 and the heat exchange tube 2, connect the extraction pipe to the other end of the heat exchange tube 1 and the heat exchange tube 2, and then connect one end of the four temperature measuring probes to the temperature control box, and the other ends to the constant temperature box 1, the constant temperature box 2 and the extraction pipe, so that the injected fluid can enter the heat exchange tube 1 and the heat exchange tube 2 in the constant temperature box 1 and the constant temperature box 2 respectively along the injection pipe, and be discharged from the same extraction pipe. The size of the heat exchange tube 1 and the heat exchange tube 2 is 1.5m long; Step S22, turn on the power of the temperature control box, set the temperature of the thermostat box 1 to 15°C and the temperature of the thermostat box 2 to 75°C according to the actual formation temperature of the study area, and turn on the heating button until the temperature in the thermostat box 1 and the thermostat box 2 is heated to the set temperature and remains stable; Step S23, close the connecting valve 1, open the connecting valve 2, so that all the fluid enters only the thermostat 2, simulating the connecting well type; Step S24, open valve 1, valve 3, valve 6 and valve 7, close the remaining valves, remove pipeline 1, connect one end to the liquefied CO2 storage tank, and connect the other end to valve 2 and valve 6 respectively, inject CO2 into the first gas cylinder and the second gas cylinder, wait for a while until the pressure between the first gas cylinder and the second gas cylinder is equal, close valve 2, valve 3, valve 6 and valve 7, remove pipeline 1, restore to the initial state, and connect the outlet to the injection pipe; Step S25, opening valve 1, valve 4, valve 5 and valve 8, so as to inject water into the first gas cylinder and the second gas cylinder through the flow pump to push CO2 into the injection pipe; Step S26, opening the hydraulic control system, setting the injection pressure to 10 MPa and 20 MPa, and starting to inject the fluid; Step S27, after a period of time, when the temperature displayed by the temperature control box is stable, observe and record the temperature data at the outlet of the extraction pipe; Step S28, open both the connecting valve 1 and the connecting valve 2, at which time the fluid flows through the heat exchange tube 1 and the heat exchange tube 2 at the same time, simulating the branch well type, and then set the temperature of the thermostat box 2 to 100°C and 150°C respectively, and the temperature of the thermostat box 1 remains unchanged. After the displayed temperature of the thermostat box is stabilized again, observe and record the temperature data at the outlet of the production pipe; Step S29, analyzing the data. The temperature data reflects the heat exchange capacity of the fluid under different well types.

[0015] Therefore, the present invention adopts the above-mentioned experimental device and method for heat extraction from injection and production fluid under high temperature and high pressure conditions, which can realize the comparison of heat extraction capacity of connecting wells and branch wells under indoor conditions, the comparison of heat extraction capacity of water and CO2, the influence of different heat exchange tube specifications on heat extraction capacity, and the comparison of heat extraction capacity under different temperature, pressure and flow rate conditions.

[0016] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A schematic diagram of a serial connection of an experimental device and method for extracting heat from injection and production fluid under high temperature and high pressure conditions according to the present invention; Figure 2 A schematic diagram of a parallel connection of an experimental device and method for extracting heat from injection and production fluid under high temperature and high pressure conditions according to the present invention; Figure 3It is a structural schematic diagram of a gas injection assembly of an embodiment of an experimental device and method for injecting and extracting heat from fluid under high temperature and high pressure conditions of the present invention; Figure 4 This is a series type experimental flow chart of an experimental device and method for extracting heat from injection and production fluid under high temperature and high pressure conditions according to the present invention; Figure 5 It is a parallel type experimental flow chart of an experimental device and method for extracting heat from injection and production fluid under high temperature and high pressure conditions of the present invention; Figure numerals: 1. hydraulic control system; 2. constant temperature box 1; 3. constant temperature box 2; 4. injection pipe; 5. production pipe; 6. connecting pipe; 7. connecting valve 1; 8. connecting valve 2; 9. temperature control box; 10. temperature measuring probe; 11. first gas cylinder; 12. second gas cylinder; 13. first three-way valve; 14. second three-way valve; 15. third three-way valve; 16. fourth three-way valve; 17. pipeline 1; 18. pipeline 2; 19. valve 1; 20. valve 2; 21. valve 3; 22. valve 4; 23. valve 5; 24. valve 6; 25. valve 7; 26. valve 8; 27. piston. DETAILED DESCRIPTION

[0018] The technical solution of the present invention is further described below through the accompanying drawings and embodiments.

[0019] Unless otherwise defined, the technical terms or scientific terms used in the present invention should be understood by people with ordinary skills in the field to which the present invention belongs. The words "first", "second" and similar words used in the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. "Include" or "comprise" and similar words mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0020] Example See also Figure 1-5 The present invention provides an experimental device for injecting and extracting heat from fluid under high temperature and high pressure conditions, including a gas injection component, a hydraulic control system 1, a high temperature and high pressure system, and a data acquisition and temperature control system.

[0021] like Figure 3As shown, the gas injection assembly includes a first gas cylinder 11, a second gas cylinder 12, a first three-way valve 13, a second three-way valve 14, a third three-way valve 15 and a fourth three-way valve 16. The first three-way valve 13 and the second three-way valve 14 are respectively arranged at the upper and lower ends of the first gas cylinder 11, the third three-way valve 15 and the fourth three-way valve 16 are respectively arranged at the upper and lower ends of the second gas cylinder 12, the first three-way valve 13 and the third three-way valve 15 are connected through a pipeline 17, and an outlet is arranged at the end of the pipeline 17, the second three-way valve 14 and the fourth three-way valve 16 are connected through a pipeline 2 18, and the end of the pipeline 2 18 is connected to the flow rate pump. The first three-way valve 13 is provided with a valve 19 and a valve 2 20, the second three-way valve 14 is provided with a valve 3 21 and a valve 4 22, the third three-way valve 15 is provided with a valve 5 23 and a valve 6 24, and the fourth three-way valve 16 is provided with a valve 7 25 and a valve 8 26. The maximum volume of a single gas cylinder is 2L. A piston 27 is provided in the first gas cylinder 11 and the second gas cylinder 12. Water is injected into the gas cylinder through a flow pump to increase the pressure at one end of the piston 27, thereby pushing the piston 27 to gradually discharge the CO2 filled at the other end.

[0022] The hydraulic control system 1 includes a computer, a flow rate pump, a back pressure valve and a condenser. The hydraulic control system 1 can inject a selected fluid into the experimental device, wherein the computer can display the flow rate and injection pressure of the injected fluid in real time; the flow rate pump controls the flow rate of the injected fluid, and the maximum injection flow rate can reach 10ml / min; the back pressure valve controls the pressure in the entire device, and as the injected fluid accumulates in the device, the pressure in the entire system increases until it reaches the set pressure and can be discharged, and the maximum injection pressure can reach 20MPa. The condenser can cool the high-temperature fluid discharged after heat exchange. The hydraulic control system 1 is a structure in the prior art and will not be described in detail here.

[0023] The high temperature and high pressure system includes an injection pipe 4, a heat exchange pipe, a production pipe 5, a thermostat and a connecting valve. The opening and closing of the connecting valve determines whether the injected fluid can enter the heat exchange pipe from the injection pipe 4. The diameter of the heat exchange pipe, the injection pipe 4, the production pipe 5 and the connecting pipe 6 are all 6mm, the wall thickness is 2mm, and they can withstand an injection pressure of 40MPa.

[0024] The thermostat box includes a thermostat box 1 2 and a thermostat box 2 3. The thermostat box 2 3 and the thermostat box 1 2 are both provided with resistance wires and a heat preservation layer. The resistance wires can evenly heat the box body of the thermostat box, and the heat preservation layer prevents the heat inside the box body of the thermostat box from being lost to the outside. The heat exchange tube includes a heat exchange tube 1 and a heat exchange tube 2. The heat exchange tube 2 and the heat exchange tube 1 are respectively arranged inside the thermostat box 2 3 and the thermostat box 1 2.

[0025] The whole process is that the injected fluid enters the heat exchange tube through the injection pipe 4, exchanges heat in the heat exchange tube, and then enters the extraction pipe 5 and is discharged. The heat exchange tube has different lengths, including 0.25m, 0.5m, 1m, 1.5m and 6m. Different sizes determine the time the fluid stays in the heat exchange tube. Under the same flow rate, the longer the heat exchange tube, the longer the heat exchange time, and the fluid can exchange heat more fully. The extraction tube also has different sizes, which determine its heat dissipation area. The longer the length, the larger the heat dissipation area.

[0026] The data acquisition and temperature control system includes a temperature control box 9 and a temperature probe 10. Four temperature probes 10 are provided. One end of each of the four temperature probes 10 is connected to the temperature control box 9. The other end of one of the temperature probes 10 is connected to the thermostat box 1 2. The other end of one of the temperature probes 10 is connected to the thermostat box 2 3. The other ends of two temperature probes 10 are connected to the production pipe 5. The temperature control box 9 can control the temperature in the thermostat box. When the power of the temperature control box 9 is turned on and the temperature of the required thermostat box is set, the heating switch is turned on, and the resistance wire in the thermostat box starts to heat continuously. The temperature probe 10 monitors the temperature in the thermostat box in real time until the set temperature is reached. The resistance wire stops heating, and the thermostat box enters the insulation state, so that the temperature is constant at the set temperature. The temperature control box 9 can achieve a set temperature of 250°C at most. In addition, since there are two temperature probes 10 connected to both ends of the production pipe 5, the display screen of the temperature control box 9 can also display the temperature of the fluid at both ends of the production pipe 5.

[0027] Example 1 Taking a certain place as the study area, the heat exchange injection-production experiment was carried out to simulate the sandstone heat reservoir of Guantao Formation at a depth of 1600m. Ordinary experimental water was selected as the injected fluid.

[0028] like Figure 1 As shown, the connection is made in series, one end of the heat exchange tube 1 is connected to the hydraulic control system 1 through the injection tube 4, the other end of the heat exchange tube 1 is connected to one end of the heat exchange tube 2 through the connecting tube 6, and the other end of the heat exchange tube 2 is connected to the extraction tube 5. The injection tube 4 and the connecting tube 6 are respectively provided with a connecting valve 1 7 and a connecting valve 2 8.

[0029] like Figure 4 As shown, the method of the above-mentioned fluid injection and production heat extraction experimental device under high temperature and high pressure conditions includes the following steps: Step S11, connect the experimental device in series, first connect the injection pipe 4 and the extraction pipe 5 to the heat exchange tube 1 and the heat exchange tube 2 respectively, then connect one end of the four temperature probes 10 to the temperature control box 9, and the other ends to the constant temperature box 1 2, the constant temperature box 2 3 and the extraction pipe 5 respectively, and finally connect the outlet end of the constant temperature box 1 2 with the inlet end of the constant temperature box 2 3 through the connecting pipe 6, so that the injected fluid first flows through the heat exchange tube 1 in the constant temperature box 1 2 and then enters the heat exchange tube 2 in the constant temperature box 2 3. The size of the heat exchange tube 1 is selected to be 6m long, and the length of the heat exchange tube 2 is selected to be 1.5m; Step S12, turn on the power of the temperature control box 9, set the temperature of the thermostat box 1 2 to 15°C, and the temperature of the thermostat box 2 3 to 75°C according to the actual formation temperature of the study area. After setting, turn on the heating button until the temperature in the thermostat box 1 2 and the thermostat box 2 3 is heated to the set temperature and remains stable; Step S13, opening the connecting valve 1 7 and the connecting valve 2 8 to allow the injection fluid to be injected into the device; Step S14, open valve 19, valve 3 21, valve 6 24 and valve 7 25, close the remaining valves, remove pipeline 17, connect one end to the liquefied CO2 storage tank, and connect the other end to valve 20 and valve 6 24 respectively, inject CO2 into the first gas cylinder 11 and the second gas cylinder 12, wait for a while until the pressure between the first gas cylinder 11 and the second gas cylinder 12 is equal, close valve 20, valve 3 21, valve 6 24 and valve 7 25, remove pipeline 17, restore to the initial state, and connect the outlet to the injection pipe 4; Step S15, opening valve 19, valve 4 22, valve 5 23 and valve 8 26, so as to inject water into the first gas cylinder 11 and the second gas cylinder 12 through the flow pump to push CO2 into the injection pipe 4; Step S16, open the hydraulic control system 1, set the flow rate to 5 ml / min, set the injection pressure to 10 MPa and 20 MPa respectively, and start injecting the fluid; Step S17, after a period of time, when the displayed temperature of the temperature control box 9 is stable, observe and record the temperature data at the outlet of the production pipe 5; Step S18, set the temperature of the thermostat box 2 3 to 100°C and 150°C respectively, keep the temperature of the thermostat box 2 unchanged to carry out the experiment, and when the displayed temperature of the temperature control box 9 is stable again, observe and record the temperature data at the outlet of the extraction pipe 5; Step S19, analyzing the temperature data, the magnitude of the temperature data reflects the heat exchange capacity of the fluid under different injection temperature conditions.

[0030] To study the heat exchange capacity of the fluid under different injection flow rates, it is only necessary to ensure that the injection temperature and injection pressure remain unchanged, and only adjust the flow pump to control the flow rate, such as setting the flow rate to 2ml / min, 5ml / min, and 8ml / min, and analyze the flow temperature at the outlet pipe 5 under the three injection flow rates; to study the heat exchange capacity of the fluid under different injection pressures, it is only necessary to ensure that the injection temperature and injection flow rate remain unchanged, and only adjust the back pressure valve to control the pressure in the entire system, such as setting the pressure to 6MPa, 8MPa, and 10MPa, and analyze the flow temperature at the outlet pipe under the three injection pressures.

[0031] Example 2 Similarly, a certain place was selected as the study area. The simulated formation conditions were that the two pipelines of the branch wells were located at depths of 1200m and 1600m respectively, and the injection fluid was ordinary experimental water.

[0032] like Figure 2 As shown, the connection is made in parallel, one end of the heat exchange tube 1 and the heat exchange tube 2 are connected to the hydraulic control system 1 through the injection pipe 4, and the other ends of the heat exchange tube 2 and the heat exchange tube 1 are connected to the extraction pipe 5. The connection point between the injection pipe 4 and the heat exchange tube 1 and the connection point between the injection pipe 4 and the heat exchange tube 2 are respectively provided with a connecting valve 1 7 and a connecting valve 2 8.

[0033] like Figure 5 As shown, the method of the above-mentioned fluid injection and production heat extraction experimental device under high temperature and high pressure conditions includes the following steps: Step S21, connect the experimental device in parallel, connect the injection pipe 4 to one end of the heat exchange tube 1 and the heat exchange tube 2, connect the extraction pipe 5 to the other end of the heat exchange tube 1 and the heat exchange tube 2, and then connect one end of the four temperature probes 10 to the temperature control box 9, and the other ends to the constant temperature box 1 2, the constant temperature box 2 3 and the extraction pipe 5, so that the injected fluid can enter the heat exchange tube 1 and the heat exchange tube 2 in the constant temperature box 1 2 and the constant temperature box 2 3 along the injection pipe 4, and be discharged from the same extraction pipe 5. The size of the heat exchange tube 1 and the heat exchange tube 2 is 1.5m long; Step S22, turn on the power of the temperature control box 9, set the temperature of the thermostat box 1 2 to 15°C and the temperature of the thermostat box 2 3 to 75°C according to the actual formation temperature of the study area, and turn on the heating button until the temperature in the thermostat box 1 2 and the thermostat box 2 3 is heated to the set temperature and remains stable; Step S23, close the connecting valve 1 7, open the connecting valve 2 8, so that all the fluid enters only the thermostatic box 2 3, simulating the connecting well type; Step S24, open valve 19, valve 3 21, valve 6 24 and valve 7 25, close the remaining valves, remove pipeline 17, connect one end to the liquefied CO2 storage tank, and connect the other end to valve 20 and valve 6 24 respectively, inject CO2 into the first gas cylinder 11 and the second gas cylinder 12, wait for a while until the pressure between the first gas cylinder 11 and the second gas cylinder 12 is equal, close valve 20, valve 3 21, valve 6 24 and valve 7 25, remove pipeline 17, restore to the initial state, and connect the outlet to the injection pipe 4; Step S25, opening valve 19, valve 4 22, valve 5 23 and valve 8 26, so as to inject water into the first gas cylinder 11 and the second gas cylinder 12 through the flow pump to push CO2 into the injection pipe 4; Step S26, open the hydraulic control system 1, set the flow rate to 5 ml / min, set the injection pressure to 10 MPa and 20 MPa respectively, and start injecting the fluid; Step S27, after a period of time, when the displayed temperature of the temperature control box 9 is stable, observe and record the temperature data at the outlet of the production pipe 5; Step S28, open both the connecting valve 1 7 and the connecting valve 2 8, and the fluid flows through the heat exchange tube 1 and the heat exchange tube 2 at the same time, simulating a branch well type, and after the displayed temperature of the temperature control box 9 stabilizes again, observe and record the temperature data at the outlet of the production pipe 5; Step S29, analyzing the temperature data. The temperature data reflects the heat exchange capacity of the fluid under different well types.

[0034] Therefore, the present invention adopts the above-mentioned experimental device and method for heat extraction from injection and production fluid under high temperature and high pressure conditions, which can realize the comparison of heat extraction capacity of connecting wells and branch wells under indoor conditions, the comparison of heat extraction capacity of water and CO2, the influence of different heat exchange tube specifications on heat extraction capacity, and the comparison of heat extraction capacity under different temperature, pressure and flow rate conditions.

[0035] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. An experimental device for heat extraction of injection and production fluid under high temperature and high pressure conditions, characterized in that: It includes a gas injection component, a hydraulic control system, a high temperature and high pressure system and a data acquisition and temperature control system. The data acquisition and temperature control system includes a temperature control box and a temperature measuring probe. The high temperature and high pressure system includes an injection pipe, a heat exchange pipe, a production pipe, and a constant temperature box. The hydraulic control system includes a computer, a flow rate pump, a back pressure valve and a condenser. The gas injection component includes a first gas cylinder, a second gas cylinder, a first three-way valve, a second three-way valve, a third three-way valve and a fourth three-way valve; The first gas cylinder and the second gas cylinder are both provided with pistons.

2. The experimental device for heat extraction from injection and production fluid under high temperature and high pressure conditions according to claim 1, characterized in that: The first three-way valve and the second three-way valve are respectively arranged at the upper and lower ends of the first gas cylinder, the third three-way valve and the fourth three-way valve are respectively arranged at the upper and lower ends of the second gas cylinder, the first three-way valve and the third three-way valve are connected through a pipeline 1, an outlet is arranged at the end of the pipeline 1, the second three-way valve and the fourth three-way valve are connected through a pipeline 2, and the end of the pipeline 2 is connected to the flow rate pump; The first three-way valve is provided with valve one and valve two, the second three-way valve is provided with valve three and valve four, the third three-way valve is provided with valve five and valve six, and the fourth three-way valve is provided with valve seven and valve eight.

3. The experimental device for heat extraction from injection and production fluid under high temperature and high pressure conditions according to claim 2, characterized in that: The thermostatic box includes a thermostatic box 1 and a thermostatic box 2, and both the thermostatic box 2 and the thermostatic box 1 are provided with resistance wires and a heat preservation layer; The heat exchange tubes include heat exchange tube 1 and heat exchange tube 2, and heat exchange tube 2 and heat exchange tube 1 are respectively arranged inside thermostatic box 2 and thermostatic box 1.

4. The experimental device for heat extraction of injection and production fluid under high temperature and high pressure conditions according to claim 3, characterized in that: Four temperature measuring probes are provided, one end of each of the four temperature measuring probes is connected to the temperature control box, the other end of one of the temperature measuring probes is connected to the constant temperature box 1, the other end of one of the temperature measuring probes is connected to the constant temperature box 2, and the other ends of two of the temperature measuring probes are connected to the production pipe.

5. The experimental device for heat extraction from injection and production fluid under high temperature and high pressure conditions according to claim 4, characterized in that: One end of the heat exchange tube 1 is connected to the hydraulic control system through the injection pipe, the other end of the heat exchange tube 1 is connected to one end of the heat exchange tube 2 through the connecting pipe, and the other end of the heat exchange tube 2 is connected to the extraction pipe.

6. The experimental device for heat extraction from injection and production fluid under high temperature and high pressure conditions according to claim 5, characterized in that: A connecting valve 1 and a connecting valve 2 are respectively arranged on the injection pipe and the connecting pipe.

7. The experimental device for heat extraction from injection and production fluid under high temperature and high pressure conditions according to claim 4, characterized in that: One end of the heat exchange tube 1 and the heat exchange tube 2 are connected to the hydraulic control system through the injection pipe, and the other end of the heat exchange tube 2 and the heat exchange tube 1 are connected to the production pipe.

8. The experimental device for heat extraction from injection and production fluid under high temperature and high pressure conditions according to claim 7, characterized in that: A connecting valve 1 and a connecting valve 2 are respectively arranged at the connection point between the injection pipe and the heat exchange pipe 1 and the connection point between the injection pipe and the heat exchange pipe 2.

9. A method for applying the experimental device for heat extraction from fluid injection under high temperature and high pressure conditions as described in claim 6, characterized in that: The following steps are involved: Step S11, connect the experimental device in series, first connect the injection pipe and the extraction pipe to the heat exchange pipe 1 and the heat exchange pipe 2 respectively, then connect one end of the four temperature measuring probes to the temperature control box, and the other ends to the constant temperature box 1, the constant temperature box 2 and the extraction pipe respectively, and finally connect the outlet end of the constant temperature box 1 with the inlet end of the constant temperature box 2 through the connecting pipe, so that the injected fluid first flows through the heat exchange pipe 1 in the constant temperature box 1 and then enters the heat exchange pipe 2 in the constant temperature box 2. The size of the heat exchange pipe 1 is selected to be 6m long, and the length of the heat exchange pipe 2 is selected to be 1.5m; Step S12, turn on the power of the temperature control box, set the temperature of the thermostat box 1 to 15°C, and the temperature of the thermostat box 2 to 75°C according to the actual formation temperature of the study area. After setting, turn on the heating button until the temperature in the thermostat box 1 and the thermostat box 2 is heated to the set temperature and remains stable; Step S13, opening the connecting valve 1 and the connecting valve 2 to allow the injection fluid to be injected into the device; Step S14, open valve 1, valve 3, valve 6 and valve 7, close the remaining valves, remove pipeline 1, connect one end to the liquefied CO2 storage tank, and connect the other end to valve 2 and valve 6 respectively, inject CO2 into the first gas cylinder and the second gas cylinder, wait for a while until the pressure between the first gas cylinder and the second gas cylinder is equal, close valve 2, valve 3, valve 6 and valve 7, remove pipeline 1, restore to the initial state, and connect the outlet to the injection pipe; Step S15, opening valve 1, valve 4, valve 5 and valve 8, so as to inject water into the first gas cylinder and the second gas cylinder through the flow pump to push CO2 into the injection pipe; Step S16, opening the hydraulic control system, setting the injection pressure to 10 MPa and 20 MPa respectively, and starting to inject the fluid; Step S17: After a period of time, when the temperature displayed by the temperature control box is stable, observe and record the temperature data at the outlet of the extraction pipe; Step S18, set the temperature of the thermostat box 2 to 100°C and 150°C respectively, keep the temperature of the thermostat box 1 unchanged to carry out the experiment, and when the displayed temperature of the thermostat box is stable again, observe and record the temperature data at the outlet of the production pipe; Step S19, analyzing the temperature data, the magnitude of the temperature data reflects the heat extraction capacity when the injected working fluid is CO2.

10. A method for applying the experimental device for heat extraction from fluid injection under high temperature and high pressure conditions as described in claim 8, characterized in that: The following steps are involved: Step S21, connect the experimental device in parallel, connect the injection pipe to one end of the heat exchange tube 1 and the heat exchange tube 2, connect the extraction pipe to the other end of the heat exchange tube 1 and the heat exchange tube 2, and then connect one end of the four temperature measuring probes to the temperature control box, and the other ends to the constant temperature box 1, the constant temperature box 2 and the extraction pipe, so that the injected fluid can enter the heat exchange tube 1 and the heat exchange tube 2 in the constant temperature box 1 and the constant temperature box 2 respectively along the injection pipe, and be discharged from the same extraction pipe. The size of the heat exchange tube 1 and the heat exchange tube 2 is 1.5m long; Step S22, turn on the power of the temperature control box, set the temperature of the thermostat box 1 to 15°C and the temperature of the thermostat box 2 to 75°C according to the actual formation temperature of the study area, and turn on the heating button until the temperature in the thermostat box 1 and the thermostat box 2 is heated to the set temperature and remains stable; Step S23, close the connecting valve 1, open the connecting valve 2, so that all the fluid enters only the thermostat 2, simulating the connecting well type; Step S24, open valve 1, valve 3, valve 6 and valve 7, close the remaining valves, remove pipeline 1, connect one end to the liquefied CO2 storage tank, and connect the other end to valve 2 and valve 6 respectively, inject CO2 into the first gas cylinder and the second gas cylinder, wait for a while until the pressure between the first gas cylinder and the second gas cylinder is equal, close valve 2, valve 3, valve 6 and valve 7, remove pipeline 1, restore to the initial state, and connect the outlet to the injection pipe; Step S25, opening valve 1, valve 4, valve 5 and valve 8, so as to inject water into the first gas cylinder and the second gas cylinder through the flow pump to push CO2 into the injection pipe; Step S26, opening the hydraulic control system, setting the injection pressure to 10 MPa and 20 MPa, and starting to inject the fluid; Step S27, after a period of time, when the temperature displayed by the temperature control box is stable, observe and record the temperature data at the outlet of the extraction pipe; Step S28, open both the connecting valve 1 and the connecting valve 2, at which time the fluid flows through the heat exchange tube 1 and the heat exchange tube 2 at the same time, simulating the branch well type, and then set the temperature of the thermostat box 2 to 100°C and 150°C respectively, and the temperature of the thermostat box 1 remains unchanged. After the displayed temperature of the thermostat box is stabilized again, observe and record the temperature data at the outlet of the production pipe; Step S29, analyzing the data. The temperature data reflects the heat exchange capacity of the fluid under different well types.

Images