CN114673479A - Based on heterogeneous state CO2Horizon type geothermal strengthening mining method - Google Patents

Based on heterogeneous state CO2Horizon type geothermal strengthening mining method Download PDF

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CN114673479A
CN114673479A CN202210491063.6A CN202210491063A CN114673479A CN 114673479 A CN114673479 A CN 114673479A CN 202210491063 A CN202210491063 A CN 202210491063A CN 114673479 A CN114673479 A CN 114673479A
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well
heat
horizontal
geothermal
temperature
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CN114673479B (en
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徐吉钊
翟成
余旭
孙勇
陈爱坤
石克龙
丁熊
吴西卓
蔡渝梁
王帅
徐鹤翔
王宇
黄婷
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China University of Mining and Technology CUMT
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China University of Mining and Technology CUMT
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    • E—FIXED CONSTRUCTIONS
    • E21—EARTH DRILLING; MINING
    • E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
    • E21B43/25—Methods for stimulating production
    • E21B43/26—Methods for stimulating production by forming crevices or fractures
    • E21B43/2605—Methods for stimulating production by forming crevices or fractures using gas or liquefied gas
    • E—FIXED CONSTRUCTIONS
    • E21—EARTH DRILLING; MINING
    • E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
    • E21B43/30—Specific pattern of wells, e.g. optimizing the spacing of wells
    • E21B43/305—Specific pattern of wells, e.g. optimizing the spacing of wells comprising at least one inclined or horizontal well
    • E—FIXED CONSTRUCTIONS
    • E21—EARTH DRILLING; MINING
    • E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B47/00—Survey of boreholes or wells
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24T—GEOTHERMAL COLLECTORS; GEOTHERMAL SYSTEMS
    • F24T10/00—Geothermal collectors
    • F24T10/10—Geothermal collectors with circulation of working fluids through underground channels, the working fluids not coming into direct contact with the ground
    • F24T10/13—Geothermal collectors with circulation of working fluids through underground channels, the working fluids not coming into direct contact with the ground using tube assemblies suitable for insertion into boreholes in the ground, e.g. geothermal probes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/10—Geothermal energy

Abstract

The invention discloses a method based on multiphase CO2The horizon type geothermal energy intensified mining method adopts a mining mode of 'single main well transformation heat extraction-auxiliary well monitoring', greatly reduces the drilling cost and improves the utilization efficiency of single drilling; by using liquid CO2The transformation expansion cracking principle of phase change after being heated when being injected into the geothermal layer increases the volume transformation range, and the CO is continuously increased along with the continuous increase of the internal pressure and temperature while the transformation cracking is carried out2The gas becomes CO in a supercritical state2The fluid, after fracturing is completed, now CO in supercritical state2Carrying a large amount of geothermal energy after the heat exchange between the fluid and the geothermal layer, and finally carrying out high-temperature supercritical CO2The fluid enters the heat exchanger to exchange heat and cool, so that the heat extracted by the fluid is used for generating power by the power generation device, and the cooled CO is cooled after heat exchange is finished2The gas is cooled by a low-temperature condensing pipe and is liquefied into liquid CO2Thereby realizing CO2Closed-loop utilization of working media; finally, the overall exploitation efficiency of geothermal resources is improved.

Description

Based on heterogeneous state CO2Horizon type geothermal strengthening mining method
Technical Field
The invention relates to a method for preparing a catalyst based on multiphase CO2The horizon type geothermal strengthening exploitation method is mainly suitable for the geothermal high-efficiency exploitation of deep dry hot rock reservoirs with low permeability and compact rock stratums.
Background
Under the influence of increasingly scarce resource quantity and environmental pollution, the traditional energy structure faces non-negligible application threats, and frequent environmental problems bring questions to traditional energy consumption. The geothermal resources in China are very rich, and the application potential is huge. According to statistics, the base number of deep geothermal resources in China is 2.09 multiplied by 107EJ, equivalent to 856 trillion tons of standard coal. The exploitability of the deep geothermal energy is about 17 trillion tons of standard coal calculated according to the lower limit of 2 percent of the exploitation rate of the geothermal resources of the dry hot rock. Therefore, deep geothermal resource development is becoming more and more popular among countries and research researchers in the world.
According to the existing geothermal energy distribution characteristics, the method can be generally divided into shallow geothermal energy (200 m from the surface to the underground), hydrothermal geothermal energy (200 m-3000m underground) and dry hot rock geothermal energy (3000 m underground). The existing scholars mostly propose to utilize a double-well enhanced geothermal exploitation mode, and improve a hot dry rock reservoir by arranging at least one injection well and injecting high-pressure water, so that the permeability and the fluid flow rate of the hot dry rock reservoir are enhanced, then a low-temperature working medium is driven to flow through an improved reservoir fracture network to extract heat energy, and the working medium flow carrying heat is extracted and utilized through the arranged production well. The method is widely applied in the world, and better technical breakthrough is obtained, but some application limitations also exist, for example, a great amount of water resources are consumed in the process of modifying the hot dry rock reservoir by using high-pressure water, and the method has great application limitation on modifying the hot dry rock reservoir in some water resource deficient areas; the process of reforming the reservoir by high-pressure water is mostly influenced by ground stress, the generated pressure relief range is multidirectional, and the effective control of reservoir fracturing is difficult to achieve; the transformation range of the conventional reservoir transformation mode is narrow, the interval through which the working medium flows in the later period is limited, and sufficient heat is difficult to obtain; and the existing adopted double-well exploitation mode is usually limited by the transformation capability of the injection well, and the production continuation problem is easy to occur. In addition, publication numbers are: CN114033346A entitled "a method for deep geothermal exploitation based on carbon dioxide medium" discloses a method for geothermal exploitation using carbon dioxide as a heat transfer medium, which does not require high pressure water injection, but because it still requires a twin well mode and also places CO into the well2The phase change cracking device performs cracking, and CO2The phase change cracking device is relatively difficult to install and limited in cracking range, and the heat exchange medium injected into the well is supercritical CO2Therefore, not only large heating equipment and pressurizing equipment are needed, but also a large amount of energy is consumed, so that the exploitation cost of geothermal resources is high and the heat exchange efficiency is low due to the mode; thus, how to provide a method which can effectively reduceUnder the conditions of drilling construction complexity and construction cost, the heat exchange efficiency after geothermal resources are mined can be effectively ensured, and the overall mining efficiency of the geothermal resources is finally improved, so that the method is one of the research directions of the industry.
Disclosure of Invention
Aiming at the problems in the prior art, the invention provides a method based on multiphase CO2The horizon type geothermal strengthening exploitation method can effectively reduce the complexity of drilling construction and construction cost, effectively ensure the heat exchange efficiency after geothermal resources are exploited, and finally improve the overall exploitation efficiency of geothermal resources.
In order to achieve the purpose, the invention adopts the technical scheme that: based on heterogeneous state CO2The horizon type geothermal reinforced mining method comprises the following specific steps:
A. firstly, drilling downwards on the ground by using a drilling machine, so that a drill hole penetrates through an overburden stratum to reach a dry and hot rock reservoir to form a vertical shaft, wherein the vertical shaft is divided into an overburden stratum section and a dry and hot rock reservoir section, the diameter of the vertical shaft is 400mm, and the bottom of the vertical shaft enters the dry and hot rock reservoir within the range of 150mm and 200 m;
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, 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 respectively, and discharging slag and slurry during withdrawal of the drilling wells; drilling a monitoring well from the ground by using a drilling machine, and enabling the final hole position of the monitoring well to be positioned in the 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. thermal insulationThe other end of the liquid injection pipe and CO2The 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 CO2The 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 completed2Laying a geothermal exploitation system;
E. when geothermal exploitation work is started, CO is started first2Pumping the pump body for a period of time to pump the high-pressure low-temperature liquid CO in the low-temperature condensation pipe2Injecting fluid into the second horizontal well via the insulated injection pipe, low temperature liquid CO2The fluid is continuously heated in the second horizontal well under the influence of the geothermal temperature, and liquid CO is used2The fluid absorbs heat and undergoes transient phase change to form CO2Gas, because the second horizontal drilling well is blocked, the generated high-pressure expansion effect impacts and cracks the dry hot rock around the second horizontal drilling well to complete one-time impact and crack process, and then the process is repeated to start CO2After the pump body is subjected to the repeated cyclic fracturing process 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 and feeds monitoring data back to the multi-source data inversion system, the multi-source data inversion system determines the fracturing condition of the geothermal layer according to the monitoring data and adjusts CO according to the fracturing condition2The 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 stopped2The pump body works to finish the cracking process;
F. when the fracture network (13) interpenetrates the first horizontal well, the second horizontal well and the third horizontal well, liquid CO is injected due to continuous multiple circulation2Under the combined action of geothermal temperature and pressure generated by gasification, liquid CO2Fluid phase change to CO2The gas can becomeCO in supercritical state2The fluid, then CO, now in supercritical state due to the lower gas pressure in the first horizontal well and the third horizontal well2The 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 CO2Fluid 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 finished2The gas enters a low-temperature condensing pipe, and CO is cooled by the low-temperature condensing pipe2Gas re-liquefaction into liquid CO2Storing;
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.
Furthermore, the monitoring device comprises a microseismic monitoring probe, an ultrasonic probe and a gas monitoring probe, and each probe is used for isolating high temperature by adopting a thermal insulation wrapping mode. By adopting the structure, the data acquisition can be carried out on the cracking condition of the geothermal layer through various probes, and the accuracy of subsequent data processing is facilitated.
Further, 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.
Further, the azimuth angle error of the first horizontal well, the second horizontal well and the third horizontal well on the space 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 positions 60m and 120m above the third horizontal well. By adopting the arrangement, the cracking of the geothermal layer is facilitated, and the heat exchange exploitation of the geothermal layer can be better realized.
Further, the maximum withstand pressure of the high-pressure sealer is 150MPa, and the maximum withstand temperature is 500 ℃. Thus, the sealing effect can be ensured.
Further, the maximum temperature which the temperature and pressure resistant packer can bear is 600 ℃, and the maximum pressure is 200 Mpa. Thus, the sealing effect can be ensured.
Further, the heat-insulation liquid injection pipe and the heat-insulation gas 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 gas 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 150 mm. The arrangement ensures that CO injected into the geothermal layer through the heat insulation liquid injection pipe2The medium is in a liquid state, so that the subsequent work is facilitated.
Further, the CO is2The adjustable range of the injection pressure of the pump body is 10-70MPa, and the injection flow range is 5-10L/min. The parameter range can meet the requirement of cracking on CO2The smooth operation of the fracturing is ensured according to the regulation and control requirements of the pump body.
Compared with the prior art, the invention combines an injection well and an extraction well into a whole and combines the injection well and the extraction well with CO in various phases2Combined by directional pressure relief technology and CO in different phases2The area of a geothermal reservoir transformation area is enlarged by energy generated during phase change, in-situ monitoring is realized by combining various monitoring sensors, smooth implementation of fracturing is guaranteed, and a single main well transformation heat extraction-auxiliary well monitoring mining mode is provided, namely only one well extends into the geothermal layer, additional arrangement is not needed, and a monitoring well is only positioned in an overlying bottom layer; on the other hand by means of liquid CO2The transformation expansion cracking principle of phase change after being heated when being injected into the geothermal layer increases the volume transformation range, and the CO is continuously increased along with the continuous increase of the internal pressure and temperature while the transformation cracking is carried out2The gas becomes CO in a supercritical state2After fracturing is finished (namely when the fracture network is communicated with all drilled wells), the fluid enters a multi-scale hole fracture structure of the fracture network by utilizing the advantages of strong fluidity, low friction resistance and the like of the supercritical state of the fluid to ensure that CO in the supercritical state is introduced2After heat exchange between fluid and geothermal layer, the fluid carries a large amount of geothermal energy and finally CO in high-temperature supercritical state2Fluid enters the heat exchanger through the heat insulation extraction pipe for heat exchange and cooling, so that the heat extracted by the fluid is used for generating power by the power generation device, and the cooled CO is cooled after heat exchange2The gas enters a low-temperature condensing pipe, and CO is cooled by the low-temperature condensing pipe2Gas re-liquefaction into liquid CO2Is stored to be used as a working medium source for subsequent injection, thereby realizing CO2Closed-loop utilization of working media; in addition, by setting the monitoring well, the microseismic technology, the acoustic technology and the gas monitoring technology are utilized to monitor the reservoir fracturing modification process and the gas migration rule respectively, the mass data are trained and predicted by means of the existing deep learning algorithm, and the CO can be adjusted2The injection parameters of different stages of the working medium are effectively adjusted, so that the smooth implementation of fracturing is finally ensured, the heat exchange efficiency after geothermal resources are mined is effectively ensured, and the overall mining efficiency of the geothermal resources is improved.
Drawings
Fig. 1 is a schematic structural view of the present invention.
In the figure: 1-an overburden; 2-a hot dry rock reservoir; 3-a vertical shaft; 4-first horizontal drilling; 5-second horizontal drilling; 6-third horizontal drilling; 7-heat insulation liquid injection pipe; 8-high pressure sealer; 9-temperature pressure resistant packer; 10-CO2A pump body; 11-heat insulation extraction pipe; 12-a heat exchanger; 13-a heat transfer circuit; 14-a power generation device; 15-a cryocondensation tube; 16-a fracture network; 17-a multi-source data inversion system; 18-fiber optic data transmission line; 19-a monitoring well; 20-monitoring device.
Detailed Description
The present invention will be further explained below.
As shown in fig. 1, the method comprises the following specific steps:
A. firstly, drilling downwards on the ground by using a drilling machine, enabling the drill hole to penetrate through an overburden stratum 1 to reach a dry hot rock reservoir stratum 1 to form a vertical shaft 3, dividing the vertical shaft 3 into an overburden stratum section and a dry hot rock reservoir stratum section, wherein the diameter of the vertical shaft 3 is 400mm, and the bottom of the vertical shaft 3 enters the range of 150-200m inside the dry hot rock reservoir stratum 1;
B. installing a directional drill bit on a drilling machine, extending the directional drill bit into the dry and hot rock reservoir 2, and sequentially drilling the directional drill bit into three horizontal wells from the vertical well 3 along the same horizontal direction at different depths of the dry and hot rock reservoir 2, wherein the drilling diameters of the three horizontal wells are all 150-180mm, the drilling lengths are all in the range of 200-300m, and are respectively set as a first horizontal well 4, a second horizontal well 5 and a third horizontal well 6 from top to bottom, the azimuth angle errors of the first horizontal well 4, the second horizontal well 5 and the third horizontal well 6 on the spatial level are smaller than 5 degrees, the third horizontal well 6 is arranged at the bottom of the vertical well 3, and the second horizontal well 4 and the first horizontal well 3 are respectively arranged at the positions 60m and 120m above the third horizontal well 5; by adopting the arrangement, the cracking of the geothermal layer is facilitated, and the heat exchange exploitation of the geothermal layer can be better realized; and slag and slurry are discharged when the drill is withdrawn; then, drilling a monitoring well 19 from the ground by using a drilling machine, and enabling the final hole position of the monitoring well 19 to be positioned in the overburden 1 right above the first horizontal drilling well 4;
C. installing a high-pressure sealer 8 at the junction of the overburden section and the dry and hot rock reservoir section of the vertical shaft 3 to seal the dry and hot rock reservoir section of the vertical shaft 3; the maximum withstand pressure of the high-pressure sealer 8 is 150MPa, and the maximum withstand temperature is 500 ℃, so that the sealing effect of the high-pressure sealer can be ensured; then, one end of a heat insulation liquid injection pipe 7 and one end of a heat insulation extraction pipe 11 both extend into the vertical shaft 3 and penetrate through a high-pressure sealer 8, wherein one end of the heat insulation liquid injection pipe 7 extends into the second horizontal drilling well 5, and a temperature-resistant pressure packer 9 is installed at one end of the heat insulation liquid injection pipe 7 to plug the second horizontal drilling well; the maximum temperature which the temperature-resistant pressure packer 9 can bear is 600 ℃, and the maximum pressure is 200 Mpa. Thus, the sealing effect can be ensured; one end of the heat insulation extraction pipe 11 is positioned in the dry hot rock reservoir section of the vertical shaft 3;
D. the other end of the heat-insulating liquid injection pipe 7 is connected with CO2The outlet of the pump body 10 is connected, the other end of the heat insulation extraction pipe 7 is connected with the inlet of the heat exchanger 11, the heat discharge port of the heat exchanger 11 is connected with the power generation device 14 through the heat transfer pipeline 13, the fluid discharge port of the heat exchanger 11 is connected with one end of the low-temperature condensation pipe 15, and the other end of the low-temperature condensation pipe 15 is connected with the CO2The inlet of the pump body 10 is connected, then the monitoring device 20 is sent to the final hole position of the monitoring well 19, the monitoring device 20 is connected with the multisource data inversion system 17 on the ground through the optical fiber data transmission line 18, and the monitoring device 20 comprisesThe device comprises a microseismic monitoring probe, an ultrasonic probe and a gas monitoring probe, wherein each probe is used for isolating high temperature in a thermal insulation wrapping mode. By adopting the structure, the data acquisition can be carried out on the cracking condition of the geothermal layer through various different probes, the accuracy of subsequent data processing is convenient, and the multiphase CO is completed2Laying a geothermal exploitation system; the heat-insulation liquid injection pipe 7 and the heat-insulation gas extraction pipe 11 are both made of flexible materials, and the maximum temperature capable of being borne by the heat-insulation liquid injection pipe is 500 ℃; the pipe diameter of the heat-insulation liquid injection pipe 7 is 80mm, and the pipe diameter of the heat-insulation extraction pipe 11 is 150 mm. The arrangement ensures that CO injected into the geothermal layer through the heat-insulating injection pipe 72The medium is in a liquid state, so that the subsequent work is facilitated to be carried out;
E. when geothermal exploitation work is started, CO is started first2The pump body 10 is operated for a period of time to pump the high pressure cryogenic liquid CO in the cryocondensation tubes 152Injecting fluid into the second horizontal well 5 via the insulated injection pipe 7, low temperature liquid CO2The fluid is continuously heated in the second horizontal well 5 by the influence of the geothermal temperature, and the liquid CO is used2The fluid absorbs heat and undergoes transient phase change to form CO2Gas, because the second horizontal drilling well 5 is blocked, the generated high-pressure expansion effect impacts and cracks the hot dry rock around the second horizontal drilling well 5 to complete one impact cracking process, and then the process is repeated to restart the CO2After the pump body 10 is subjected to a period of time and a plurality of times of cyclic fracturing processes, the hot dry rocks around the second horizontal well 5 form a complex fracture network 16, meanwhile, the monitoring device 20 monitors the geological condition below the second horizontal well in real time and feeds monitoring data back to the multi-source data inversion system 17, the multi-source data inversion system 17 determines the fracturing condition of the geothermal layer according to the monitoring data and adjusts CO according to the fracturing condition2The injection pressure and the injection flow of the pump body 10 are detected until the second horizontal drilling well 5 is respectively communicated with the first horizontal drilling well 4 and the third horizontal drilling well 6 through the fracture network 16, and the CO stops2The pump body 10 finishes the fracturing process; the CO is2The adjustable range of the injection pressure of the pump body 10 is 10-70MPa, and the injection flow range is 5-10L/min. The parameter range can meet the requirement of cracking on CO2Regulatory requirements of the pump body 10The smooth proceeding of the fracturing is ensured;
F. when the fracture network 16 interpenetrates the first horizontal drilling well 4, the second horizontal drilling well 5 and the third horizontal drilling well 6, liquid CO is injected due to continuous multiple circulation2Under the combined action of geothermal temperature and pressure generated by gasification, liquid CO2Fluid phase change to CO2The gas will become CO in a supercritical state2The fluid, then CO in the supercritical state due to the lower gas pressure in the first horizontal well 4 and the third horizontal well 62The fluid enters the first horizontal well 4 and the third horizontal well 6 along the fracture network 16, continuously absorbs heat, and finally enters the heat insulation extraction pipe 11 through the vertical shaft 3;
G. high temperature CO2Fluid enters a heat exchanger 12 through a heat insulation extraction pipe 11, separated heat in the heat exchanger 12 enters a power generation device 14 through a heat transfer pipeline 13 in a radiation heat exchange process to generate power, and the cooled CO after heat exchange is finished2The gas enters the low-temperature condensation pipe 15, and the temperature of the gas is reduced by the low-temperature condensation pipe 15 to ensure that CO is condensed2Gas re-liquefaction into liquid CO2Storing;
H. and when the calorific value separated from the heat exchanger 12 is lower than a set value, repeating the steps E to G, so that the calorific value separated from the heat exchanger 12 is increased, circulating the steps, and finally realizing the geothermal exploitation of the dry hot rock.
The high-pressure sealer 8, the temperature-resistant packer 9 and CO2The pump body 10, the heat exchanger 12, the power generation device 14, the low-temperature condenser tube 15, the multi-source data inversion system 17 and the monitoring device 20 are all existing equipment or devices and can be obtained through market purchase; wherein, the multisource data inversion system 17 receives the monitoring data fed back by the monitoring device 20 and then adopts the known deep learning algorithm and the filtering noise reduction technology to analyze and process the monitoring data, thereby realizing the visualization of the fracturing process. Is convenient for timely adjusting CO in the follow-up process according to the cracking condition2Pressure and flow rate of the pump body. The low temperature condenser 15 can condense the inflowing CO2The gas is continuously cooled to change the phase into liquid CO2A fluid.
The above description is only of the preferred embodiments of the present invention, and it should be noted that: it will be apparent to those skilled in the art that various modifications and adaptations can be made without departing from the principles of the invention and these are intended to be within the scope of the invention.

Claims (8)

1. Based on heterogeneous state CO2The 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, 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 respectively, and discharging slag and slurry during withdrawal of the drilling wells; 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 hot rock reservoir section of the vertical shaft;
D. the other end of the heat insulation liquid injection pipe is connected with CO2The 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 CO2The inlet of the pump body is connected, then the monitoring device is sent into the final hole position of the monitoring well, and the monitoring device is connected with the multisource number on the ground through an optical fiber data transmission lineAccording to the connection of an inversion system, completing multiphase CO2Laying a geothermal exploitation system;
E. when geothermal exploitation work is started, CO is started first2Pumping the pump body for a period of time to pump the high-pressure low-temperature liquid CO in the low-temperature condensation pipe2Injecting fluid into the second horizontal well via the insulated injection pipe, low temperature liquid CO2The fluid is continuously heated in the second horizontal well under the influence of the geothermal temperature, and liquid CO is used2The fluid absorbs heat and undergoes transient phase change to form CO2Gas, because the second horizontal drilling well is blocked, the generated high-pressure expansion effect impacts and cracks the dry hot rock around the second horizontal drilling well to complete one-time impact and crack process, and then the process is repeated to start CO2After the pump body is subjected to the repeated cyclic fracturing process 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 multisource 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 condition2The injection pressure and the injection flow of the pump body are detected until the second horizontal drilling well is respectively communicated with the first horizontal drilling well and the third horizontal drilling well through the fracture network, and the CO is stopped2The pump body works to finish 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 circulation2Under the combined action of geothermal temperature and pressure generated by gasification, liquid CO2Fluid phase change to CO2The gas will become CO in a supercritical state2The fluid, then CO, now in supercritical state due to the lower gas pressure in the first horizontal well and the third horizontal well2The 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 CO2The fluid enters the heat exchanger through the heat insulation extraction pipe and passes through the spoke in the heat exchangerThe separated heat enters the power generation device through the heat transfer pipeline in the heat injection and exchange process to generate power, and the cooled CO is cooled after heat exchange is finished2The gas enters a low-temperature condensing pipe, and CO is cooled by the low-temperature condensing pipe2Gas re-liquefaction into liquid CO2Storing;
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 multiphase CO-based fuel as claimed in claim 12The horizon type geothermal energy intensified mining method is characterized in that the monitoring device comprises a microseismic monitoring probe, an ultrasonic probe and a gas monitoring probe, and each probe is used for isolating high temperature in a thermal insulation wrapping mode.
3. The multiphase CO-based fuel as claimed in claim 12The 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-.
4. The multiphase CO-based fuel as claimed in claim 12The horizon type geothermal enhanced exploitation method is characterized in that the azimuth angle error of the first horizontal well, the second horizontal well and the third horizontal well in the space horizon is less than 5 degrees, the third horizontal well is arranged at the bottom of the vertical shaft, and the second horizontal well and the first horizontal well are respectively arranged at the positions 60m and 120m above the third horizontal well.
5. The multiphase CO-based fuel as claimed in claim 12The 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. According to claim1 said one is based on multiphase state CO2The 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 200 Mpa.
7. The multiphase CO-based fuel as claimed in claim 12The 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 150 mm.
8. The multiphase CO-based fuel as claimed in claim 12The horizon-type geothermal enhanced mining method of (1), characterized in that the CO is2The 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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