CN114673479B - Based on heterogeneous state CO 2 Horizon type geothermal strengthening mining method - Google Patents

Abstract

The invention discloses a multi-phase _CO2 -based layered geothermal intensified mining method, which adopts the mining mode of "single main well reformation and heat improvement-auxiliary well monitoring", which greatly reduces the drilling cost and improves the single drilling cost. Utilization efficiency: using the principle of phase change expansion and cracking after heating when liquid CO ₂ is injected into the geothermal layer to increase the volume reformation range, and at the same time as the phase change and cracking, with the continuous increase of internal pressure and temperature, the CO ₂ gas becomes The _CO2 fluid in the supercritical state, after the cracking is completed, the _CO2 fluid in the supercritical state will carry a large amount of geothermal energy after heat exchange with the geothermal layer, and finally the _CO2 fluid in the high temperature supercritical state enters the heat exchanger. The heat exchange is carried out to cool down, so that the extracted heat is used for the power generation device to generate electricity. After the heat exchange is completed, the cooled CO ₂ gas is cooled down and re-liquefied into liquid CO ₂ through the low temperature condenser, thus realizing the closed-loop utilization of CO ₂ working fluid; finally Improve the overall mining efficiency of geothermal resources.

Description

A Horizontal Geothermal Enhanced Mining Method Based on Multiphase CO2

technical field

The invention relates to a multiphase _CO2 -based stratum-type geothermal intensified mining method, which is mainly suitable for high-efficiency geothermal mining of deep hot dry rock reservoirs with low permeability and dense rock formations.

Background technique

Affected by increasingly scarce resources and environmental pollution, the traditional energy structure is facing application threats that cannot be ignored, and frequent environmental problems have also brought doubts to traditional energy consumption. my country's geothermal resources are very rich and have great application potential. According to statistics, the base of China's deep geothermal resources is 2.09×10 ⁷ EJ, equivalent to 856 trillion tons of standard coal. Calculated according to the 2% lower limit of the exploitation rate of hot dry rock geothermal resources, the exploitable amount of deep geothermal energy is about 17 trillion tons of standard coal. Therefore, the development of deep geothermal resources is increasingly favored by countries and researchers all over the world.

According to the distribution characteristics of existing geothermal energy, it can generally be divided into shallow geothermal energy (surface to 200m underground), hydrothermal geothermal energy (200m-3000m underground), and dry hot rock geothermal energy (under 3000m underground). Existing scholars often propose to use the double-well enhanced geothermal recovery mode to modify the hot dry rock reservoir by setting at least one injection well to inject high-pressure water to enhance its permeability and fluid flow, and then drive the low-temperature working fluid to flow through the modified geothermal reservoir. The reservoir fracture network extracts heat energy, and the working medium flow carrying heat is extracted and utilized through the set production wells. This method has been widely used all over the world and has achieved relatively good technological breakthroughs, but there are also some application limitations. For example, using high-pressure water to stimulate dry hot rock reservoirs will consume a lot of water resources, there are great limitations in the application of hot dry rock reservoir stimulation in some water-scarce areas; the process of high-pressure water stimulation reservoirs is mostly affected by in-situ stress, and the range of pressure relief produced is multi-directional, making it difficult to achieve Effective control of layer fracturing; conventional reservoir stimulation methods have a narrow stimulation range, and the later period of working fluid flow is limited, so it is difficult to obtain sufficient heat; and the existing dual-well production mode is often limited Due to the stimulation ability of injection wells, production continuity problems are prone to occur. In addition, the publication number is: CN114033346A, and the invention patent titled "a deep geothermal mining method based on carbon dioxide medium" discloses a method for geothermal mining using carbon dioxide as a heat transfer medium. Although it does not require high-pressure water injection, it still requires The double well mode is set up, and a CO ₂ phase-change cracker is also installed in the well for fracturing, but the installation of the CO ₂ phase-change cracker is relatively difficult, and the cracking range is limited, and the heat exchange medium injected into the well is Supercritical CO ₂ , which not only requires large-scale heating equipment and pressurization equipment, but also consumes a lot of energy. Therefore, this method will also lead to high mining costs of geothermal resources and low heat exchange efficiency; therefore, how to provide a method , can effectively reduce the complexity and cost of drilling construction, and can effectively ensure the heat transfer efficiency after geothermal resources are exploited, and ultimately improve the overall exploitation efficiency of geothermal resources, which is one of the research directions of this industry.

Contents of the invention

Aiming at the problems existing in the above-mentioned prior art, the present invention provides a multi-phase _CO2 -based layer-type geothermal enhanced mining method, which can effectively reduce the complexity and construction cost of drilling construction, and can effectively ensure the exploitation of geothermal resources The final heat exchange efficiency will ultimately improve the overall exploitation efficiency of geothermal resources.

In order to achieve the above object, the technical solution adopted in the present invention is: a layer-type geothermal enhanced mining method based on multiphase CO ₂ , the specific steps are:

A. First, use a drilling rig to drill downward on the ground, so that the borehole passes through the overlying strata to reach the hot dry rock reservoir to form a shaft. The shaft is divided into the overlying stratum section and the hot dry rock reservoir section. The diameter of the shaft is 300- 400mm, the bottom of the shaft enters within 150-200m of the hot dry rock reservoir;

B. Install the directional drill bit on the drilling rig, and extend the directional drill bit into the hot dry rock reservoir, so that the directional drill bit drills in sequence from the shaft along the same horizontal direction at different depths in the hot dry rock reservoir to form three horizontal drilling wells, and from From top to bottom, the first horizontal drilling, the second horizontal drilling and the third horizontal drilling are respectively set, and the slag and slurry are discharged when the drilling is withdrawn; In the overburden directly above the first horizontal well;

C. Install a high-pressure sealer at the junction of the overlying formation section and the hot dry rock reservoir section of the shaft to seal off the hot dry rock reservoir section of the shaft; Extend into the shaft and pass through the high-pressure sealer, where one end of the heat-insulating liquid injection pipe extends into the second horizontal drilling, and a heat-resistant and pressure-resistant packer is installed at one end of the heat-insulating liquid injection pipe to seal the second horizontal drilling; heat insulation One end of the extraction pipe is located in the hot dry rock reservoir section of the shaft;

D. The other end of the insulated liquid injection pipe is connected to the outlet of the _CO2 pump body, the other end of the adiabatic extraction pipe is connected to the inlet of the heat exchanger, and the heat outlet of the heat exchanger is connected to the power generation device through the heat transfer pipeline for heat exchange The fluid discharge outlet of the device is connected to one end of the cryogenic condenser tube, and the other end of the cryogenic condenser tube is connected to the inlet of the _CO2 pump body, and then the monitoring device is sent to the end hole of the monitoring well, and the monitoring device is connected to the multiple on the ground through the optical fiber data transmission line. The source data inversion system is connected, and the layout of the multiphase CO ₂ geothermal recovery system is completed;

E. When starting geothermal exploitation, first start the _CO2 pump body for a period of time, so that it can inject the high-pressure and low-temperature liquid _CO2 fluid in the low-temperature condensation pipe into the second horizontal drilling through the heat-insulating liquid injection pipe, and the low-temperature liquid _CO2 fluid at the first The temperature in the second horizontal drilling continues to rise due to the influence of geothermal temperature. At this time, the liquid CO ₂ fluid undergoes a transient phase transition during the heat absorption process to form CO ₂ gas. Since the second horizontal drilling is blocked, the high-pressure expansion generated by it has a negative effect on the second horizontal drilling. The hot dry rock around the drilling well is subjected to impact fracturing, and the impact fracturing process is completed once, and then the above process is repeated and the CO ₂ pump body is started for a period of time. After several cycles of fracturing, the hot dry rock around the second horizontal drilling A complex fracture network is formed. At the same time, the monitoring device monitors the geological conditions below in real time, and feeds the monitoring data back to the multi-source data inversion system. The multi-source data inversion system determines the fracturing of the geothermal layer based on the monitoring data. And adjust the injection pressure and injection flow rate of the CO ₂ pump body according to the fracturing situation until the second horizontal drilling well is monitored to pass through the fracture network to the first horizontal drilling well and the third horizontal drilling well respectively, and the CO ₂ pump body is stopped to complete the work. cracking process;

F. When the fracture network (13) connects the first horizontal well, the second horizontal well and the third horizontal well, the liquid _CO2 fluid injected continuously for multiple cycles is under the joint action of the geothermal temperature and the pressure generated by gasification , the liquid CO ₂ fluid phase changes to form CO ₂ gas will become CO ₂ fluid in supercritical state, and then due to the lower gas pressure in the first horizontal drilling and the third horizontal drilling, the CO ₂ fluid in supercritical state at this time Enter the first horizontal drilling well and the third horizontal drilling well along the fracture network, and continue to absorb heat, and finally enter the adiabatic extraction pipe through the shaft;

G. The high-temperature CO ₂ fluid enters the heat exchanger through the adiabatic extraction pipe. In the heat exchanger, through the radiation heat exchange process, the separated heat enters the power generation device through the heat transfer pipeline for power generation. After the heat exchange is completed, the cooled CO ₂ The gas enters the cryogenic condenser, and the CO ₂ gas is re-liquefied into liquid CO ₂ for storage through the cooling effect of the cryogenic condenser;

H. When the heat value separated by the heat exchanger is lower than the set value, repeat steps E to G, so as to increase the heat value separated by the heat exchanger, and so on, and finally realize the geothermal exploitation of hot dry rock.

Further, the monitoring device includes microseismic monitoring probes, ultrasonic probes and gas monitoring probes, and each probe is wrapped in thermal insulation to isolate high temperature. With this structure, data can be collected on the fracturing of the geothermal layer through a variety of different probes, which facilitates the accuracy of subsequent data processing.

Further, the drilling diameters of the first horizontal drilling, the second horizontal drilling and the third horizontal drilling are all 150-180mm, and the drilling lengths are all in the range of 200-300m.

Further, the azimuth error of the first horizontal drilling, the second horizontal drilling and the third horizontal drilling on the spatial horizon is less than 5°, the third horizontal drilling is arranged at the bottom of the shaft, the second horizontal drilling and the first horizontal drilling Drilling wells are respectively arranged at positions 60m and 120m above the third horizontal drilling well. Adopting this arrangement not only facilitates fracturing of the geothermal layer, but also better realizes heat exchange exploitation of the geothermal layer.

Further, the maximum withstand pressure of the high pressure sealer is 150MPa, and the maximum withstand temperature is 500°C. This can ensure its sealing effect.

Furthermore, the maximum temperature and pressure that the temperature and pressure resistant packer can withstand is 600°C and 200Mpa. This can ensure its sealing effect.

Further, both the heat-insulated liquid injection pipe and the heat-insulated extraction pipe are made of flexible materials, and the maximum temperature they can withstand is 500°C; the diameter of the heat-insulated liquid injection pipe is 80 mm, and the diameter of the heat-insulated extraction pipe is 150 mm. This setting ensures that the _CO2 medium injected into the geothermal layer through the adiabatic liquid injection pipe is in a liquid state, which facilitates the development of follow-up work.

Further, the injection pressure of the CO ₂ pump body can be adjusted in the range of 10-70MPa, and the injection flow range is in the range of 5-10L/min. This parameter range can meet the control requirements of the CO ₂ pump during fracturing and ensure the smooth progress of fracturing.

Compared with the prior art, the present invention combines the injection well and the extraction well into one, and combines it with various phases of CO ₂ , through directional pressure relief technology and different phases of CO ₂ phase transitions to generate The energy of the geothermal reservoir can be expanded to expand the area of geothermal reservoir stimulation, and multiple monitoring sensors can be combined to realize in-situ monitoring to ensure the smooth progress of fracturing. Into the geothermal layer, there is no need for additional installations, and the monitoring well is only located in the overlying bottom layer. On the one hand, this method forms a single-well production that can integrate reservoir transformation, working fluid-driven heat extraction, and working fluid heating. method, which greatly reduces the drilling cost and improves the utilization efficiency of a single well; on the other hand, when liquid CO ₂ is injected into the geothermal layer, the principle of phase change expansion fracturing after heating is used to increase the volume reconstruction range, and at the same time of phase change fracturing, As the internal pressure and temperature continue to increase, the CO ₂ gas becomes a CO ₂ fluid in a supercritical state. After the fracturing is completed (that is, when the fracture network connects each drilling well), at this time, the strong flow of the supercritical state is used Advantages such as high resistance and low friction enter into the multi-scale pore-fracture structure of the fracture network so that the CO ₂ fluid in the supercritical state exchanges heat with the geothermal layer, and carries a large amount of geothermal energy. Finally, the CO ₂ fluid in the high-temperature supercritical state passes through the adiabatic The extraction pipe enters the heat exchanger for heat exchange and cooling, so that the extracted heat is used in the power generation device to generate electricity. After the heat exchange is completed, the cooled CO ₂ gas enters the low-temperature condenser tube, and the CO ₂ gas is regenerated through the cooling effect of the low-temperature condenser tube. Liquefied into liquid _CO2 for storage, as a source of working fluid for subsequent injection, thus realizing the closed-loop utilization of _CO2 working fluid; in addition, through the setting of monitoring wells, microseismic technology, acoustic wave technology and gas monitoring technology are used to monitor reservoir fracturing In the transformation process and gas migration law, with the help of the existing deep learning algorithm to train and predict massive data, it can effectively adjust the injection parameters of different stages of CO ₂ working fluid, and finally ensure the smooth progress of fracturing and effectively ensure the geothermal energy. The heat exchange efficiency after resource mining improves the overall mining efficiency of geothermal resources.

Description of drawings

Fig. 1 is a structural schematic diagram of the present invention.

In the figure: 1-overlying formation; 2-hot dry rock reservoir; 3-vertical well; 4-first horizontal drilling; 5-second horizontal drilling; 6-third horizontal drilling; 7-insulation liquid injection pipe; 8 -high pressure sealer; 9-temperature and pressure resistant packer; 10-CO ₂ pump body; 11-insulated extraction pipe; 12-heat exchanger; 13-heat transfer pipeline; 14-power generation device; 15-low temperature condensation 16-fracture network; 17-multi-source data inversion system; 18-optical fiber data transmission line; 19-monitoring well; 20-monitoring device.

Detailed ways

The present invention will be further described below.

As shown in Figure 1, the concrete steps of the present invention are:

A. First, use a drilling rig to drill downwards on the ground, so that the borehole passes through the overlying stratum 1 to reach the hot dry rock reservoir 1 to form a shaft 3. The shaft 3 is divided into an overlying stratum section and a hot dry rock reservoir section. 3 has a diameter of 300-400mm, and the bottom of shaft 3 enters within 150-200m of hot dry rock reservoir 1;

B. Install the directional drill bit on the drilling rig, and extend the directional drill bit into the hot dry rock reservoir 2, so that the directional drill bit drills sequentially from the shaft 3 along the same horizontal direction at different depths in the hot dry rock reservoir 2 to form three horizontal drilling wells , the drilling diameters of the three horizontal drilling wells are all 150-180mm, the drilling lengths are all in the range of 200-300m, and they are respectively set as the first horizontal drilling 4, the second horizontal drilling 5 and the third horizontal drilling 6 from top to bottom , the azimuth error of the first horizontal drilling 4, the second horizontal drilling 5 and the third horizontal drilling 6 on the spatial horizon is less than 5°, the third horizontal drilling 6 is arranged at the bottom of the shaft 3, the second horizontal drilling 4 and The first horizontal drilling well 3 is respectively arranged at positions 60m and 120m above the third horizontal drilling well 5; adopting this arrangement not only facilitates cracking of the geothermal layer, but also better realizes heat exchange and exploitation of the geothermal layer; Slag discharge and slurry discharge; then use a drilling rig to drill a monitoring well 19 from the ground, so that the final hole position of the monitoring well 19 is in the overlying formation 1 directly above the first horizontal drilling 4;

C. Install a high-pressure sealer 8 at the junction of the overlying formation section of the vertical shaft 3 and the hot dry rock reservoir section to seal off the hot dry rock reservoir section of the vertical shaft 3; the maximum withstand pressure of the high pressure sealer 8 is 150MPa, The maximum withstand temperature is 500°C, which can ensure its sealing effect; then both the end of the heat-insulating liquid injection pipe 7 and the end of the heat-insulated extraction pipe 11 are extended into the shaft 3 and passed through the high-pressure sealer 8, wherein the heat-insulated liquid injection pipe One end of 7 extends into the second horizontal drilling 5, and a heat-resistant and pressure-resistant packer 9 is installed at one end of the adiabatic liquid injection pipe 7 to seal the second horizontal drilling; the maximum temperature that the temperature-resistant and pressure-resistant packer 9 can withstand is 600 ℃, the maximum pressure is 200Mpa. This can ensure its sealing effect; one end of the heat-insulating extraction pipe 11 is located in the hot dry rock reservoir section of the shaft 3;

D, the other end of the heat-insulating liquid injection pipe 7 is connected to the outlet of the _CO2 pump body 10, the other end of the heat-insulated extraction pipe 7 is connected to the inlet of the heat exchanger 11, and the heat outlet of the heat exchanger 11 is connected to the heat transfer pipeline 13 The power generation device 14 is connected, the fluid outlet of the heat exchanger 11 is connected to one end of the low-temperature condensation pipe 15, and the other end of the low-temperature condensation pipe 15 is connected to the inlet of the _CO2 pump body 10, and then the monitoring device 20 is sent into the end hole of the monitoring well 19 position, the monitoring device 20 is connected to the multi-source data inversion system 17 on the ground through the optical fiber data transmission line 18, and the monitoring device 20 includes microseismic monitoring probes, ultrasonic probes and gas monitoring probes, and each probe is used for thermal insulation wrapping. for high temperature isolation. Adopting this structure can carry out data acquisition to the fracturing situation of geothermal layer by a variety of different probes, facilitate the accuracy of follow-up data processing, and complete the layout work of the multiphase _CO2 geothermal recovery system; the heat-insulating liquid injection pipe 7 and The adiabatic extraction pipe 11 is made of flexible materials, and the maximum temperature it can withstand is 500°C; the diameter of the adiabatic liquid injection pipe 7 is 80 mm, and the diameter of the adiabatic extraction pipe 11 is 150 mm. This arrangement ensures that the _CO2 medium injected into the geothermal layer by the heat-insulating liquid injection pipe 7 is in a liquid state, which is convenient for the development of follow-up work;

E. When starting geothermal exploitation work, start the _CO2 pump body 10 for a period of time to make it inject the high-pressure and low-temperature liquid _CO2 fluid in the low-temperature condensation pipe 15 into the second horizontal drilling 5 through the heat-insulating liquid injection pipe 7, and the low-temperature liquid The CO ₂ fluid in the second horizontal drilling 5 is affected by the geothermal temperature and continues to heat up. At this time, the liquid CO ₂ fluid undergoes a transient phase change during the heat absorption process to form CO ₂ gas. Since the second horizontal drilling 5 is blocked, the produced The high-pressure expansion impacts the hot dry rock around the second horizontal drilling 5 to complete a shock fracturing process, and then repeats the above process and starts the CO ₂ pump body 10 for a period of time. After multiple cyclic fracturing processes, the The hot dry rock around the second horizontal drilling 5 forms a complex fracture network 16, while the monitoring device 20 monitors the geological conditions below in real time, and feeds the monitoring data back to the multi-source data inversion system 17, the multi-source data inversion system 17 Determine the fracturing situation of the geothermal layer according to the monitoring data, and adjust the injection pressure and injection flow rate of the _CO2 pump body 10 according to the fracturing situation until the second horizontal drilling 5 passes through the fracture network 16 and respectively connects with the first horizontal drilling well. 4 and the third horizontal drilling 6 break through, stop the CO ₂ pump body 10 to complete the fracturing process; the injection pressure of the CO ₂ pump body 10 can be adjusted in the range of 10-70MPa, and the injection flow range is 5-10L/min . This parameter range can meet the control requirements of the _CO2 pump body 10 during fracturing, and ensure the smooth progress of fracturing;

F. When the fracture network 16 connects the first horizontal well 4, the second horizontal well 5 and the third horizontal well 6, the liquid _CO2 fluid injected continuously for multiple cycles acts together at the geothermal temperature and the pressure generated by gasification Next, liquid CO ₂ fluid phase transition forms CO ₂ gas will become _CO in supercritical state Fluid, then because the air pressure in the first horizontal drilling 4 and the third horizontal drilling 6 is low, now the gas in supercritical state The CO ₂ fluid enters the first horizontal well 4 and the third horizontal well 6 along the fracture network 16, continues to absorb heat, and finally enters the heat-insulated extraction pipe 11 through the shaft 3;

G. The high-temperature _CO2 fluid enters the heat exchanger 12 through the adiabatic extraction pipe 11, and the separated heat enters the power generation device 14 through the heat transfer pipeline 13 through the radiation heat exchange process in the heat exchanger 12 to generate electricity, and the heat exchange is completed Afterwards, the cooled _CO2 gas enters the low-temperature condensation pipe 15, and the _CO2 gas is re-liquefied into liquid _CO2 by the cooling effect of the low-temperature condensation pipe 15 for storage;

H. When the heat value separated by the heat exchanger 12 is lower than the set value, repeat steps E to G, thereby increasing the heat value separated by the heat exchanger 12, and so on, and finally realize the geothermal exploitation of the hot dry rock.

The above-mentioned high-pressure sealer 8, temperature-resistant and pressure-resistant packer 9, _CO2 pump body 10, heat exchanger 12, power generation device 14, cryogenic condenser tube 15, multi-source data inversion system 17 and monitoring device 20 are all existing equipment or devices, which can be obtained through market purchase; where the multi-source data inversion system 17 uses known deep learning algorithms and filtering and noise reduction techniques to analyze and process the monitoring data after receiving the monitoring data fed back by the monitoring device 20, so as to achieve Visualization of cracking process. It is convenient to adjust the pressure and flow rate of the _CO2 pump body in time according to the fracturing situation. The low-temperature condensation pipe 15 can continuously lower the temperature of the inflowing CO ₂ gas, so that its phase changes into a liquid CO ₂ fluid.

The above is only a preferred embodiment of the present invention, it should be pointed out that for those of ordinary skill in the art, without departing from the principle of the present invention, some improvements and modifications can also be made, and these improvements and modifications are also possible. It should be regarded as the protection scope of the present invention.

Claims (8)

1. Based on heterogeneous state CO ₂ The horizon type geothermal reinforced mining method is characterized by comprising the following specific steps:

A. firstly, drilling downwards on the ground by using a drilling machine, so that a drilled hole penetrates through an overburden stratum to reach a dry hot rock reservoir to form a vertical shaft, and the vertical shaft is divided into an overburden stratum section and a dry hot rock reservoir section;

B. installing a directional drill bit on a drilling machine, extending the directional drill bit into the hot dry rock reservoir, sequentially drilling the directional drill bit at different depths of the hot dry rock reservoir along the same horizontal direction from a vertical shaft to form three horizontal drilling wells, respectively setting the three horizontal drilling wells as a first horizontal drilling well, a second horizontal drilling well and a third horizontal drilling well from top to bottom, and discharging slag and slurry during the back drilling; drilling a monitoring well from the ground by using a drilling machine, and enabling the final hole position of the monitoring well to be located in an overlying stratum right above the first horizontal drilling well;

C. installing a high-pressure sealer at the junction of the overburden section and the dry and hot rock reservoir section of the vertical shaft to seal the dry and hot rock reservoir section of the vertical shaft; then, one end of a heat insulation liquid injection pipe and one end of a heat insulation extraction pipe both extend into the vertical well and penetrate through the high-pressure sealer, wherein one end of the heat insulation liquid injection pipe extends into a second horizontal well, and a temperature-resistant pressure packer is installed at one end of the heat insulation liquid injection pipe to plug the second horizontal well; one end of the heat insulation extraction pipe is positioned in a dry and hot rock reservoir section of the vertical shaft;

D. the other end of the heat-insulating liquid injection pipe and CO ₂ The outlet of the pump body is connected, the other end of the heat insulation extraction pipe is connected with the inlet of the heat exchanger, the heat discharge port of the heat exchanger is connected with the power generation device through the heat transfer pipeline, the fluid discharge port of the heat exchanger is connected with one end of the low-temperature condensation pipe, and the other end of the low-temperature condensation pipe is connected with the CO ₂ The inlet of the pump body is connected, then the monitoring device is sent to the final hole position of the monitoring well, the monitoring device is connected with the multisource data inversion system on the ground through an optical fiber data transmission line, and the multiphase CO is completed ₂ Laying a geothermal exploitation system;

E. when geothermal exploitation work is started, CO is started first ₂ Pumping the pump body for a period of time to pump the high-pressure low-temperature liquid CO in the low-temperature condensation pipe ₂ Injecting fluid into the second horizontal well via the insulated injection pipe, low temperature liquid CO ₂ The fluid is continuously heated in the second horizontal well under the influence of geothermal temperature, and liquid CO is obtained ₂ The fluid absorbs heat and undergoes transient phase change to form CO ₂ Gas, because the second horizontal drilling well is blocked, the generated high-pressure expansion effect impacts and cracks the hot dry rock around the second horizontal drilling well to complete one impact cracking process, and then the process is repeated to restart CO ₂ After the pump body is subjected to a plurality of times of cyclic fracturing processes for a period of time, the hot dry rock around the second horizontal drilling well forms a complex fracture network, meanwhile, the monitoring device monitors the geological condition below the second horizontal drilling well in real time, the monitoring data are fed back to the multi-source data inversion system to determine the fracturing condition of the geothermal layer according to the monitoring data, and the CO is adjusted according to the fracturing condition ₂ The injection pressure and the injection flow of the pump body are controlled until the second horizontal drilling well is communicated with the first horizontal drilling well and the third horizontal drilling well through the fracture network respectively, and the CO is stopped ₂ The pump body finishes the cracking process;

F. when the fracture network interpenetrates the first horizontal well, the second horizontal well and the third horizontal well, the liquid CO is injected due to continuous multiple circulation ₂ The liquid CO is generated by the combined action of geothermal temperature and pressure generated by gasification ₂ Fluid phase change to CO ₂ The gas will become CO in a supercritical state ₂ The fluid, then CO in the supercritical state due to the lower gas pressure in the first horizontal well and the third horizontal well ₂ The fluid enters a first horizontal well and a third horizontal well along the fracture network, continuously absorbs heat, and finally enters an insulated extraction pipe through a vertical well;

G. high temperature CO ₂ Fluid enters the heat exchanger through the heat insulation extraction pipe, separated heat in the heat exchanger enters the power generation device through the heat transfer pipeline in the radiation heat exchange process to generate power, and the cooled CO after heat exchange is finished ₂ The gas enters the low-temperature condenser pipe, and the CO is cooled by the low-temperature condenser pipe ₂ Gas re-liquefaction into liquid CO ₂ Storing;

H. and E, when the heat value separated by the heat exchanger is lower than a set value, repeating the steps from E to G, so that the heat value separated by the heat exchanger is increased, and circulating the steps in such a way, and finally realizing the geothermal exploitation of the dry hot rock.

2. The method of claim 1 based on multiphase CO ₂ The horizon-type geothermal intensified mining method is characterized in that the monitoring deviceThe device comprises a microseismic monitoring probe, an ultrasonic probe and a gas monitoring probe, wherein each probe is used for isolating high temperature by adopting a thermal insulation wrapping mode.

3. The multiphase CO-based fuel as claimed in claim 1 ₂ The method for the horizon type geothermal enhanced exploitation is characterized in that the drilling diameters of the first horizontal drilling well, the second horizontal drilling well and the third horizontal drilling well are all 150-180mm, and the drilling lengths are all in the range of 200-300 m.

4. The method of claim 1 based on multiphase CO ₂ The horizon type geothermal energy intensified mining method is characterized in that the azimuth angle error of the first horizontal well, the second horizontal well and the third horizontal well on the spatial horizon is less than 5 degrees, the third horizontal well is arranged at the bottom position of the vertical shaft, and the second horizontal well and the first horizontal well are respectively arranged at the positions of 60m and 120m above the third horizontal well.

5. The multiphase CO-based fuel as claimed in claim 1 ₂ The horizon type geothermal strengthening exploitation method is characterized in that the maximum withstand pressure of the high-pressure sealer is 150MPa, and the maximum withstand temperature is 500 ℃.

6. The multiphase CO-based fuel as claimed in claim 1 ₂ The horizon type geothermal strengthening exploitation method is characterized in that the maximum temperature which the temperature and pressure resistant packer can bear is 600 ℃, and the maximum pressure is 200Mpa.

7. The method of claim 1 based on multiphase CO ₂ The horizon type geothermal energy reinforced exploitation method is characterized in that the heat insulation liquid injection pipe and the heat insulation extraction pipe are both made of flexible materials, and the maximum temperature capable of being borne by the heat insulation liquid injection pipe and the heat insulation extraction pipe is 500 ℃; the pipe diameter of the heat-insulation liquid injection pipe is 80mm, and the pipe diameter of the heat-insulation extraction pipe is 150mm.

8. A method according to claim 1, based on multiple phasesCO ₂ The horizon-type geothermal enhanced mining method of (1), characterized in that the CO is ₂ The adjustable range of the injection pressure of the pump body is 10-70MPa, and the injection flow range is 5-10L/min.

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