CN114673480B - Based on heterogeneous CO 2 Multi-lateral-layer position type geothermal enhanced mining method for medium - Google Patents
Based on heterogeneous CO 2 Multi-lateral-layer position type geothermal enhanced mining method for medium Download PDFInfo
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- 238000000034 method Methods 0.000 title claims abstract description 45
- 238000005065 mining Methods 0.000 title claims abstract description 17
- 238000005553 drilling Methods 0.000 claims abstract description 139
- 239000007788 liquid Substances 0.000 claims abstract description 53
- 239000012530 fluid Substances 0.000 claims abstract description 50
- 239000011435 rock Substances 0.000 claims abstract description 44
- 238000005338 heat storage Methods 0.000 claims abstract description 38
- 238000005336 cracking Methods 0.000 claims abstract description 16
- 230000008859 change Effects 0.000 claims abstract description 13
- 238000010248 power generation Methods 0.000 claims abstract description 11
- 238000009413 insulation Methods 0.000 claims description 47
- 238000002347 injection Methods 0.000 claims description 40
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- 238000012546 transfer Methods 0.000 claims description 8
- 238000009833 condensation Methods 0.000 claims description 7
- 230000005494 condensation Effects 0.000 claims description 7
- 125000004122 cyclic group Chemical group 0.000 claims description 6
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- 238000007906 compression Methods 0.000 claims description 3
- 238000007599 discharging Methods 0.000 claims description 3
- 238000002309 gasification Methods 0.000 claims description 3
- 230000005855 radiation Effects 0.000 claims description 3
- 239000002893 slag Substances 0.000 claims description 3
- 239000002002 slurry Substances 0.000 claims description 3
- 230000001052 transient effect Effects 0.000 claims description 3
- 238000005086 pumping Methods 0.000 claims description 2
- 230000009466 transformation Effects 0.000 abstract description 8
- 238000004519 manufacturing process Methods 0.000 description 7
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 4
- 238000010276 construction Methods 0.000 description 4
- 238000005516 engineering process Methods 0.000 description 3
- 230000004048 modification Effects 0.000 description 3
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- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 3
- 229910002092 carbon dioxide Inorganic materials 0.000 description 2
- 239000001569 carbon dioxide Substances 0.000 description 2
- 239000003245 coal Substances 0.000 description 2
- 238000011160 research Methods 0.000 description 2
- 238000007789 sealing Methods 0.000 description 2
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK 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
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK 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. optimising the spacing of wells
- E21B43/305—Specific pattern of wells, e.g. optimising the spacing of wells comprising at least one inclined or horizontal well
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- 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
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- 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
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Abstract
The invention discloses a method based on multiphase CO 2 A multi-lateral-layer geothermal intensified mining method for a medium comprises the steps of drilling a vertical shaft from the ground to a dry hot rock reservoir, sequentially forming a heat storage pool, a first horizontal drilling group, a second horizontal drilling group and a third horizontal drilling group in the vertical shaft, and distributing multi-phase CO 2 A geothermal mining system; by using liquid CO 2 The phase change expansion cracking principle after being heated when being injected into the geothermal layer increases the volume transformation range, and enables CO to be cracked in phase change manner 2 The gas becomes CO in a supercritical state 2 Fluid, CO in supercritical state after completion of fracturing 2 After heat exchange is carried out between the fluid and the geothermal layer, the fluid is concentrated and gathered in a heat storage pool formed in advance according to the plume characteristics of the fluid and the geothermal layer, and finally CO in a supercritical state 2 The 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; therefore, the heat exchange efficiency after the geothermal resources are mined is effectively ensured, and the overall mining efficiency of the geothermal resources is improved.
Description
Technical Field
The invention relates to a method based on multiphase CO 2 The method is mainly suitable for the geothermal efficient exploitation of dry-hot rock strata with wide reservoir area, compact stratum structure and poor permeability.
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 radix of deep geothermal resources in China is 2.09 multiplied by 10 7 EJ, equivalent to 856 trillion tons standard coal. The exploitation amount of deep geothermal energy is about 17 trillion tons of standard coal by calculating according to the lower limit of 2 percent of the exploitation rate of 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.
The mode mainly considers three main links of strengthening modification of an injection well, heat carrying of low-temperature fluid and heat lifting of a production well, a fracture structure is formed by fracturing modification of a geothermal reservoir, low-temperature working media are driven to move along the fracture structure to carry a large amount of geothermal energy, and finally heat is lifted and taken through the production well. The method has achieved certain successful practice, but still has certain technical shortcomings, for example, the method reforms the reservoir through the hydraulic measure, on one hand, a large amount of water resources are consumed, and on the other hand, for many water resource-deficient areas, the geothermal exploitation cost is undoubtedly and greatly increased, and on the other hand, the method improves the reservoir through the hydraulic measure, and on the other hand, the method can not only save the geothermal exploitation cost, but also can save the energy, and on the other hand, the method can save the energy and save the energyAfter the geothermal reservoir is modified, more single cracks are generated, the low-temperature working medium has a limited heat extraction range, and efficient heat extraction is difficult to realize; according to the method, an injection well and a production well need to be drilled, the ground arrangement of the production well is mostly limited by the reservoir transformation fracture expansion direction, the practical situation of ground drilling is difficult to consider sometimes, the contradiction between the exploitation progress and the place of origin is easy to cause, meanwhile, the drilling of the production well needs to consume a large amount of manpower and material resources, the site selection of the production well needs to be determined by means of geophysical prospecting technologies such as microseisms, the accuracy of data analysis and inversion of the microseisms technology is poor, and the correctness of site selection of the production well is difficult to achieve. 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 still requires a twin well pattern and CO to be placed in the well 2 The phase change cracking device performs cracking, and CO 2 The 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 CO 2 Therefore, 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; therefore, how to provide a method can effectively ensure the heat exchange efficiency after geothermal resources are exploited under the condition of effectively reducing the complexity of drilling construction and the construction cost, and finally improve the overall exploitation efficiency of the geothermal resources is one of the research directions in the industry.
Disclosure of Invention
Aiming at the problems in the prior art, the invention provides a multiphase CO-based catalyst 2 The multi-lateral-layer geothermal strengthening exploitation method of the medium 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 the geothermal resources.
In order to achieve the purpose, the invention adopts the technical scheme that: based on heterogeneous CO 2 Multi-lateral-layer position type geothermal enhanced mining method for medium, in particular to a method for mining geothermal energy in a multi-lateral-layer position type geothermal enhanced mining methodThe method comprises the following steps:
A. firstly, drilling downwards on the ground by using a drilling machine, so that a drill hole penetrates through an overlying rock stratum to reach a dry hot rock reservoir to form a vertical shaft, and the vertical shaft is divided into an overlying rock layer section and a dry hot rock reservoir section; the diameter of the vertical shaft is 350-400 mm, and the bottom of the vertical shaft enters the dry and hot rock storage layer within the range of 180-200 m;
B. installing a directional drill bit on a drilling machine, reaming the wall of the vertical shaft well at a position 40-60 m away from the overburden layer at the dry and hot rock storage layer section of the vertical shaft through the directional drill bit, and forming a heat storage pool after reaming; drilling four horizontal wells in the hot dry rock reservoir along four different directions from the vertical shaft at a distance below the heat storage pool through a directional drill bit at the same horizontal plane to serve as a first horizontal well drilling group, and drilling four horizontal wells in the hot dry rock reservoir along four different directions from the vertical shaft at a distance below the first horizontal well drilling group through the directional drill bit at the same horizontal plane to serve as a second horizontal well drilling group; finally, drilling four horizontal wells in the hot dry rock reservoir along four different directions from the vertical shaft at the same horizontal plane through a directional drill bit at a distance below the second horizontal well drilling group to serve as a third horizontal well drilling group, and discharging slag and slurry during withdrawal of the wells;
C. installing a high-pressure well plugging device at the junction of the overburden section and the dry and hot rock reservoir section of the vertical shaft to plug 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 well plugging device, wherein one end of the heat insulation liquid injection pipe extends into the second horizontal well drilling group, one end of the heat insulation liquid injection pipe is connected with an inlet of a four-way flow divider, four outlets of the four-way flow divider are respectively a horizontal pipe I, a horizontal pipe II, a horizontal pipe III and a horizontal pipe IV, the initial state is a compression state, the heat insulation liquid injection pipe enters a dry and hot rock reservoir and is popped out and stretched by thermal expansion, and the horizontal pipe I, the horizontal pipe II, the horizontal pipe III and the horizontal pipe IV are respectively inserted into four horizontal well drilling of the second horizontal well drilling group; one end of the heat insulation extraction pipe is positioned in the heat storage pool;
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-insulating extraction pipe is connected with the inlet of the heat exchanger, and the heat discharge port of the heat exchanger is connected with the power generation device through the heat transfer pipelineThe fluid outlet of the heat exchanger is connected with one end of a low-temperature condensing tube, and the other end of the low-temperature condensing tube is connected with CO 2 The inlet of the pump body is connected to complete multi-phase CO 2 Laying a geothermal exploitation system;
E. when geothermal exploitation is started, CO is started first 2 Pumping the liquid CO into the low-temperature condenser tube for a period of time 2 Fluid is respectively injected into each horizontal well of the second horizontal well group through the first horizontal pipe, the second horizontal pipe, the third horizontal pipe and the fourth horizontal pipe by the heat insulation liquid injection pipe and the four-way flow divider, and the four-way flow divider is used for adjusting CO 2 The flow rate of the fluid entering the four horizontal pipes controls the pressure in each pipe, and low-temperature liquid CO 2 The fluid is continuously heated in four horizontal drilling wells of the second horizontal drilling well group under the influence of the geothermal temperature, and at the moment, the liquid CO is heated 2 The fluid absorbs heat and undergoes transient phase change to form CO 2 The gas, the high pressure expansion effect produced by the gas, impacts and cracks the dry hot rock around each of the four horizontal drilling wells to complete one-time impact cracking process, and then the process is repeated to start CO 2 After the pump body is subjected to cyclic fracturing for a period of time, the hot dry rocks around the second horizontal drilling group form a complex fracture network, and if an overpressure or underpressure state occurs in one horizontal drilling hole in the cyclic fracturing process, the four-way diverter is adjusted to control the CO entering the horizontal pipe corresponding to the horizontal drilling hole 2 Reducing or increasing the fluid flow so as to keep the fracturing effect of the four horizontal drilling wells, and completing the fracturing process until the second horizontal drilling well group is communicated with the first horizontal drilling well group and the third horizontal drilling well group through the fracture network;
F. when the fracture network interpenetrates the first horizontal drilling group, the second horizontal drilling group and the third horizontal drilling group, the liquid CO is continuously injected for multiple times of circulation 2 Under the combined action of geothermal temperature and pressure generated by gasification, liquid CO 2 Phase change of fluid to form CO 2 The gas will become CO in a supercritical state 2 Fluid, then due to the lower gas pressure in the first horizontal drilling group and the third horizontal drilling groupCO in the supercritical state 2 The fluid enters the first horizontal drilling group and the third horizontal drilling group along the fracture network, continuously absorbs heat, and finally CO in a supercritical state 2 The fluid is gathered in the heat storage pool through the vertical shaft due to the plume characteristic;
G. CO in heat storage tank 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 a low-temperature condensing pipe, and CO is cooled by the low-temperature condensing 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 E to G, so that the heat value separated by the heat exchanger is increased, circulating the steps in such a way, and finally realizing the geothermal exploitation of the dry hot rock.
Further, the horizontal wells of each of the first, second and third horizontal well groups are at 90 ° therebetween; and the azimuthal error of the horizontal borehole between groups at the spatial horizon is less than 5 deg.. 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, in the step B, the horizontal drilling diameters of the first horizontal drilling group, the second horizontal drilling group and the third horizontal drilling group are all 100-120 mm, and the drilling lengths are all in the range of 150-200 m; the first horizontal drilling group is positioned in the range of 20-40 m below the heat storage pool, the second horizontal drilling group is positioned in the range of 80-100 m below the heat storage pool, and the third horizontal drilling group is positioned in the range of 140-180 m below the heat storage pool.
Furthermore, the first horizontal pipe, the second horizontal pipe, the third horizontal pipe and the fourth horizontal pipe are all provided with one-way valves. The structure is added, so that each horizontal pipe can flow in a single direction, and CO injected into the horizontal drilling well is prevented 2 And (5) medium backflow.
Further, the maximum tolerance pressure of the high-pressure blowout preventer is 150MPa, and the maximum tolerance temperature is 500 ℃. Thus ensuring its sealing effect.
Further, the shape of the heat storage pool is an ellipsoid shape, the radius of the heat storage pool along the radial direction of the vertical shaft is 30m, and the radius of the heat storage pool along the axial direction of the vertical shaft is 10m. By adopting the heat storage tank with the shape and the size, the supercritical CO in the heat storage tank can be effectively realized 2 The converging effect of the fluid.
Further, the heat-insulation liquid injection pipe, the heat-insulation gas extraction pipe, the first horizontal pipe, the second horizontal pipe, the third horizontal pipe and the fourth horizontal pipe are all made of flexible materials, and the maximum temperature capable of being borne by the heat-insulation liquid injection pipe, the heat-insulation gas extraction pipe, the first horizontal pipe, the second horizontal pipe, the third horizontal pipe and the fourth horizontal pipe is 500 ℃; the pipe diameter of the heat-insulation liquid injection pipe is 120mm, and the pipe diameter of the heat-insulation extraction pipe is 150mm; the pipe diameters of the first horizontal pipe, the second horizontal pipe, the third horizontal pipe and the fourth horizontal pipe are all 80mm. The arrangement ensures that CO is injected into the geothermal layer through the heat-insulation liquid injection pipe and the horizontal pipes 2 The medium is in a liquid state, so that the subsequent work is facilitated.
Further, the CO is 2 The adjustable range of the injection pressure of the pump body is 10-70 MPa, and the injection flow range is 5-10L/min. The parameter range can meet the requirement of cracking on CO 2 The 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 phases 2 Combined by directional pressure relief technology and CO in different phases 2 The area of a geothermal reservoir transformation area is enlarged by energy generated during phase change, and a single-main-well transformation heat-extraction mining mode is realized, namely only one well extends into the geothermal layer without being additionally arranged, so that on one hand, a single-well mining mode capable of integrating the reservoir transformation, working medium driving heat extraction, working medium heat extraction and other processes is formed, the drilling cost is greatly reduced, and the utilization efficiency of single drilling is improved; on the other hand using liquid CO 2 The 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 out 2 The gas becomes CO in a supercritical state 2 After fracturing is finished (namely, when the fracture network is communicated with each drilling group), the fluid utilizes the strong fluidity, low frictional resistance and the like of the supercritical stateMaking CO in supercritical state enter multiscale Kong Liexi structure of fracture network 2 After the fluid exchanges heat with the geothermal layer, a large amount of geothermal energy is carried, and then CO in a supercritical state is carried 2 The fluid is concentrated and gathered in a heat storage pool formed in advance according to the characteristics of the plume, and finally CO in a supercritical state 2 Fluid 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 power generation of the power generation device, and the cooled CO after heat exchange is finished 2 The gas enters a low-temperature condensing pipe, and CO is cooled by the low-temperature condensing pipe 2 Gas re-liquefaction into liquid CO 2 Is stored to be used as a working medium source for subsequent injection, thereby realizing CO 2 Closed-loop utilization of working media; therefore, the heat exchange efficiency after the geothermal resources are mined is effectively ensured, and the overall mining efficiency of the geothermal resources is improved.
Drawings
FIG. 1 is a schematic view of the overall structure of the present invention;
FIG. 2 is a top plan view of the first horizontal well group of FIG. 1;
FIG. 3 is a side view of a four-way diverter of the present invention;
fig. 4 is a top view of fig. 3.
In the figure: 1-an overburden; 2-a hot dry rock reservoir; 3-a vertical shaft; 4-a first horizontal drilling group; 5-a second horizontal drilling group; 6-a third horizontal drilling group; 7-a heat storage pool; 8-CO 2 A pump body; 9-heat insulation liquid injection pipe; 10-high pressure blowout preventer; 11-a four-way diverter; 11-1-horizontal pipe I; 11-2-horizontal pipe II; 11-3-horizontal pipe III; 11-4-horizontal tube four; 12-heat insulation extraction pipe; 13-a heat exchanger; 14-a heat transfer circuit; 15-a power generation device; 16-a cryocondensation tube; 17-fracture network.
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, so that a drill hole penetrates through an overburden 1 to reach a dry hot rock reservoir 2 to form a vertical shaft 3, and the vertical shaft 3 is divided into an overburden layer section and a dry hot rock reservoir section; the diameter of the vertical shaft 3 is 350-400 mm, and the bottom of the vertical shaft 3 enters the range of 180-200 m in the dry hot rock reservoir 2;
B. installing a directional drill bit on a drilling machine, reaming the wall of the vertical shaft 3 at a position 40-60 m away from the overburden layer of the dry and hot rock reservoir of the vertical shaft 3 through the directional drill bit, and forming a heat storage pool 7 after reaming; the thermal storage tank 7 is formed in an ellipsoidal shape, and has a radius of 30m in the radial direction of the shaft 3 and a radius of 10m in the axial direction of the shaft 3. By adopting the heat storage tank 7 with the shape and the size, the heat storage tank 7 can effectively realize the supercritical state CO 2 The converging effect of the fluid. Drilling four horizontal wells in the hot dry rock reservoir 2 from the vertical shaft 3 in four different directions at a distance below the heat storage pool 7 through a directional drill bit on the same horizontal plane to serve as a first horizontal well drilling group 4, and drilling four horizontal wells in the hot dry rock reservoir 2 from the vertical shaft 3 in four different directions at a distance below the first horizontal well drilling group 4 through the directional drill bit on the same horizontal plane to serve as a second horizontal well drilling group 5; finally, drilling four horizontal wells in the hot dry rock reservoir 2 from the vertical well 3 along four different directions on the same horizontal plane at a distance below the second horizontal well drilling group 5 through a directional drill bit to serve as a third horizontal well drilling group 6, and discharging slag and slurry during withdrawal of the wells; the horizontal drilling angles of the first horizontal drilling group 4, the second horizontal drilling group 5 and the third horizontal drilling group 6 are 90 degrees; and the azimuthal error of the horizontal borehole between groups at the spatial horizon is less than 5 deg.. 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; wherein the horizontal drilling diameters of the first horizontal drilling group 4, the second horizontal drilling group 5 and the third horizontal drilling group 6 are all 100-120 mm, and the drilling lengths are all in the range of 150-200 m; the first horizontal drilling group 4 is positioned in the range of 20-40 m below the heat storage pool 7, the second horizontal drilling group 5 is positioned in the range of 80-100 m below the heat storage pool 7, and the third horizontal drilling group 6 is positioned in the range of 140-180 m below the heat storage pool 7;
C. and installing a high-pressure blowout preventer 10 at the junction of the overburden section and the dry hot rock reservoir section of the vertical shaft 3, wherein the maximum withstand pressure of the high-pressure blowout preventer 10 is 150MPa, and the maximum withstand temperature is 500 ℃. Thus, the sealing effect can be ensured; dry hot rock storage for shaft 3Plugging the layer section; then, one end of a heat insulation liquid injection pipe 9 and one end of a heat insulation extraction pipe 12 both extend into the vertical shaft 3 and penetrate through the high-pressure well plugging device 10, wherein one end of the heat insulation liquid injection pipe 9 extends into the second horizontal well group 5, one end of the heat insulation liquid injection pipe 9 is connected with an inlet of a four-way flow divider 11, four outlets of the four-way flow divider 11 are respectively a first horizontal pipe 11-1, a second horizontal pipe 11-2, a third horizontal pipe 11-3 and a fourth horizontal pipe 11-4, the initial state is a compression state, and the heat insulation liquid injection pipe enters the dry and hot rock reservoir layer 2 to be heated, expanded, ejected and extended, so that the first horizontal pipe 11-1, the second horizontal pipe 11-2, the third horizontal pipe 11-3 and the fourth horizontal pipe 11-4 are respectively inserted into four horizontal wells of the second horizontal well group 5; one end of the heat insulation extraction pipe 12 is positioned in the heat storage pool 7; wherein, the first horizontal pipe 11-1, the second horizontal pipe 11-2, the third horizontal pipe 11-3 and the fourth horizontal pipe 11-4 are all provided with one-way valves. The structure is added, so that each horizontal pipe can flow in a single direction, and CO injected into the horizontal drilling well is prevented 2 Medium backflow;
D. the other end of the heat insulation liquid injection pipe 9 and CO 2 The outlet of the pump body 8 is connected, the other end of the heat insulation extraction pipe 12 is connected with the inlet of the heat exchanger 13, the heat discharge port of the heat exchanger 13 is connected with the power generation device 15 through the heat transfer pipeline 14, the fluid discharge port of the heat exchanger 13 is connected with one end of the low-temperature condensation pipe 16, and the other end of the low-temperature condensation pipe 16 is connected with the CO 2 The inlet of the pump body 8 is connected to complete multiphase CO 2 Laying a geothermal exploitation system; wherein the heat insulation liquid injection pipe 9, the heat insulation extraction pipe 12, the first horizontal pipe 11-1, the second horizontal pipe 11-2, the third horizontal pipe 11-3 and the fourth horizontal pipe 11-4 are made of flexible materials and can bear the maximum temperature of 500 ℃; the pipe diameter of the heat-insulation liquid injection pipe 9 is 120mm, and the pipe diameter of the heat-insulation extraction pipe 12 is 150mm; the pipe diameters of the first horizontal pipe 11-1, the second horizontal pipe 11-2, the third horizontal pipe 11-3 and the fourth horizontal pipe 11-4 are all 80mm. The arrangement ensures that CO injected into the geothermal layer through the heat insulation liquid injection pipe 9 and each horizontal pipe 2 The medium is in a liquid state, so that the subsequent work is facilitated.
E. When geothermal exploitation work is started, CO is started first 2 Pump body 8 for a period of time, CO 2 The adjustable range of the injection pressure of the pump body 8 is 10-70 MPa, and the injection flow range is 5-10L/min. The parameter range can meet the requirement of CO in cracking 2 The pump body 8 is required to be regulated and controlled, so that the fracturing is ensured to be smoothly carried out; so that the high-pressure low-temperature liquid CO in the low-temperature condensation pipe 16 is mixed with the high-pressure low-temperature liquid CO 2 Fluid is respectively injected into each horizontal well of the second horizontal well group 5 through a first horizontal pipe 11-1, a second horizontal pipe 11-2, a third horizontal pipe 11-3 and a fourth horizontal pipe 11-4 by the aid of a heat insulation liquid injection pipe 9 and a four-way flow divider 11, and the four-way flow divider 11 adjusts CO 2 The flow rate of the fluid entering the four horizontal pipes controls the pressure in each pipe, and the low-temperature liquid CO 2 The fluid is continuously heated up by the influence of the geothermal temperature in the four horizontal drilling wells of the second horizontal drilling well group 5, and the liquid CO is used 2 The fluid absorbs heat and undergoes transient phase change to form CO 2 The gas, the high pressure expansion effect produced by the gas, impacts and cracks the dry hot rock around each of the four horizontal drilling wells to complete one-time impact cracking process, and then the process is repeated to start CO 2 After the pump body 8 is subjected to a plurality of cyclic cracking processes for a period of time, the hot dry rocks around the second horizontal drilling group 5 form a complex fracture network, and in the cyclic cracking process, if an overpressure or underpressure state occurs in one of the horizontal drilling wells, the four-way diverter 11 is adjusted to control the CO entering the horizontal pipe corresponding to the horizontal drilling well 2 The flow rate of the fluid is reduced or increased, so that the fracturing effect of the four horizontal drilling wells is kept, and the fracturing process is completed until the second horizontal drilling well group 5 is communicated with the first horizontal drilling well group 4 and the third horizontal drilling well group 6 through the fracture network 17;
F. when the fracture network 17 interpenetrates the first horizontal drilling group 4, the second horizontal drilling group 5 and the third horizontal drilling group 6, the liquid CO is continuously injected for a plurality of times in a circulating manner 2 Under the combined action of geothermal temperature and pressure generated by gasification, liquid CO 2 Phase change of fluid to form CO 2 The gas will become CO in a supercritical state 2 The fluid, then CO, now in a supercritical state due to the lower gas pressure in the first 4 and third 6 horizontal drilling strings 2 The fluid enters the first horizontal drilling group 4 and the third horizontal drilling group 6 along the fracture network 17 and continuously absorbs heat, and finally CO in a supercritical state 2 Fluid due toThe plume characteristics of the heat exchange pool are gathered in the heat storage pool 7 through a vertical shaft;
G. CO in the heat storage tank 7 2 Fluid enters a heat exchanger 13 through a heat insulation extraction pipe 12, separated heat in the heat exchanger 13 enters a power generation device 15 through a heat transfer pipeline 14 in a 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 16, and the temperature of the gas is reduced by the low-temperature condenser pipe 16 to ensure that CO is condensed 2 Gas is liquefied into liquid CO 2 Storing;
H. and (4) when the heat value separated by the heat exchanger 13 is lower than a set value, repeating the steps from E to G, so that the heat value separated by the heat exchanger 13 is increased, and circulating the steps in such a way, and finally realizing geothermal exploitation of the dry hot rock.
The high pressure blowout preventer 10, the four-way flow divider 11 and CO 2 The pump body 8, the heat exchanger 13, the power generation device 15, the low-temperature condensation pipe 16 and the one-way valve are all existing equipment or devices and can be purchased and obtained in the market; wherein the cryocondensation tubes 16 are capable of condensing the inflowing CO 2 The gas is continuously cooled to change the phase into liquid CO 2 A fluid. The four-way splitter 11 has CO regulation 2 The flow rate of the fluid entering the four horizontal pipes controls the pressure in each horizontal pipe, and if an overpressure or underpressure condition occurs in one of the horizontal drilling wells, the four-way diverter 11 is adjusted to control the CO entering the horizontal pipe corresponding to the horizontal drilling well 2 The fluid flow is reduced or increased to maintain the fracturing effect of the four horizontal wells.
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 CO 2 The multi-lateral layer position type geothermal strengthening mining method of the medium 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 layer to reach a dry hot rock reservoir layer to form a vertical shaft, and the vertical shaft is divided into an overburden layer section and a dry hot rock reservoir section;
B. installing a directional drill bit on a drilling machine, reaming the wall of the vertical shaft well at a position 40-60 m away from the overburden layer at the dry and hot rock storage layer section of the vertical shaft through the directional drill bit, and forming a heat storage pool after reaming; drilling four horizontal wells in the hot dry rock reservoir along four different directions from the vertical shaft at a distance below the heat storage pool through a directional drill bit at the same horizontal plane to serve as a first horizontal well drilling group, and drilling four horizontal wells in the hot dry rock reservoir along four different directions from the vertical shaft at a distance below the first horizontal well drilling group through the directional drill bit at the same horizontal plane to serve as a second horizontal well drilling group; finally, drilling four horizontal wells in the hot dry rock reservoir along four different directions from the vertical shaft at the same horizontal plane through a directional drill bit at a distance below the second horizontal well drilling group to serve as a third horizontal well drilling group, and discharging slag and slurry during withdrawal of the wells;
C. installing a high-pressure blowout preventer at the junction of the overburden reservoir section and the dry and hot rock reservoir section of the vertical shaft, and plugging 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 well plugging device, wherein one end of the heat insulation liquid injection pipe extends into the second horizontal well drilling group, one end of the heat insulation liquid injection pipe is connected with an inlet of a four-way flow divider, four outlets of the four-way flow divider are respectively a horizontal pipe I, a horizontal pipe II, a horizontal pipe III and a horizontal pipe IV, the initial state is a compression state, the heat insulation liquid injection pipe enters a dry and hot rock reservoir and is popped and stretched by thermal expansion, and the horizontal pipe I, the horizontal pipe II, the horizontal pipe III and the horizontal pipe IV are respectively inserted into four horizontal well drilling of the second horizontal well drilling group; one end of the heat insulation extraction pipe is positioned in the heat storage pool;
D. the other end of the heat insulation liquid injection pipe is connected with 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 to complete multi-phase CO 2 Laying a geothermal mining system;
E. when geothermal exploitation 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 Fluid is respectively injected into each horizontal well of the second horizontal well group through the first horizontal pipe, the second horizontal pipe, the third horizontal pipe and the fourth horizontal pipe by the heat insulation liquid injection pipe and the four-way flow divider, and the four-way flow divider is used for adjusting CO 2 The flow rate of the fluid entering the four horizontal pipes controls the pressure in each pipe, and low-temperature liquid CO 2 The fluid is continuously heated by the influence of geothermal temperature in four horizontal drilling wells of the second horizontal drilling well group, and the liquid CO is heated 2 The fluid absorbs heat and undergoes transient phase change to form CO 2 The gas, the high pressure expansion effect produced by the gas, impacts and cracks the dry hot rock around each of the four horizontal drilling wells to complete one-time impact cracking process, and then the process is repeated to start CO 2 After the pump body is subjected to cyclic fracturing for a period of time, the hot dry rocks around the second horizontal drilling group form a complex fracture network, and if an overpressure or underpressure state occurs in one horizontal drilling in the cyclic fracturing process, the CO entering the horizontal pipe corresponding to the horizontal drilling is subjected to adjustment of the four-way flow divider 2 Reducing or increasing the fluid flow so as to keep the fracturing effect of the four horizontal drilling wells, and completing the fracturing process until the second horizontal drilling well group is communicated with the first horizontal drilling well group and the third horizontal drilling well group through the fracture network;
F. when the fracture network interpenetrates the first horizontal drilling group, the second horizontal drilling group and the third horizontal drilling group, the liquid CO is continuously injected for multiple times of circulation 2 Under the combined action of geothermal temperature and pressure generated by gasification, liquid CO 2 Fluid phase change to CO 2 The gas will become CO in a supercritical state 2 The fluid, then CO in a supercritical state due to the lower gas pressure in the first horizontal drilling group and the third horizontal drilling group 2 The fluid enters the first horizontal drilling group and the third horizontal drilling group along the fracture network, continuously absorbs heat, and finally CO in a supercritical state 2 The fluid passes through due to its plume characteristicsThe vertical shaft is converged in the heat storage pool;
G. CO in heat storage tank 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 a low-temperature condensing pipe, and CO is cooled by the low-temperature condensing 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 multiphase CO-based according to claim 1 2 The method is characterized in that horizontal drilling wells of the first horizontal drilling well group, the second horizontal drilling well group and the third horizontal drilling well group are 90 degrees; and the azimuthal error of the horizontal borehole between groups at the spatial horizon is less than 5 deg..
3. The multiphase CO-based according to claim 1 2 The multi-lateral-layer geothermal enhanced mining method for the medium is characterized in that in the step B, the horizontal drilling diameters of the first horizontal drilling group, the second horizontal drilling group and the third horizontal drilling group are all 100-120 mm, and the drilling lengths are all in the range of 150-200 m; the first horizontal drilling group is positioned in the range of 20-40 m below the heat storage pool, the second horizontal drilling group is positioned in the range of 80-100 m below the heat storage pool, and the third horizontal drilling group is positioned in the range of 140-180 m below the heat storage pool.
4. The multiphase CO-based according to claim 1 2 The medium multi-side layer position type geothermal strengthening exploitation method is characterized in that the first horizontal pipe, the second horizontal pipe, the third horizontal pipe and the fourth horizontal pipe are all provided with one-way valves.
5. The base of claim 1In multiphase CO 2 The multi-lateral-layer horizontal geothermal enhanced mining method of the medium is characterized in that the maximum withstand pressure of the high-pressure blowout preventer is 150MPa, and the maximum withstand temperature is 500 ℃.
6. The multiphase CO-based according to claim 1 2 The multi-lateral-layer position type geothermal enhanced mining method of the medium is characterized in that the heat storage pool is in an ellipsoid shape, the radius of the heat storage pool along the radial direction of the vertical shaft is 30m, and the radius of the heat storage pool along the axial direction of the vertical shaft is 10m.
7. The multiphase CO-based according to claim 1 2 The multi-lateral-layer position type geothermal energy intensified mining method of the medium is characterized in that the heat insulation liquid injection pipe, the heat insulation extraction pipe, the first horizontal pipe, the second horizontal pipe, the third horizontal pipe and the fourth horizontal pipe are made of flexible materials, and the maximum temperature capable of being borne by the flexible materials is 500 ℃; the pipe diameter of the heat-insulation liquid injection pipe is 120mm, and the pipe diameter of the heat-insulation extraction pipe is 150mm; the pipe diameters of the first horizontal pipe, the second horizontal pipe, the third horizontal pipe and the fourth horizontal pipe are all 80mm.
8. Multiphase CO-based in accordance with claim 1 2 Method for the lateral zonal geothermal-intensified exploitation of a medium, characterized in that said CO is introduced into a medium 2 The adjustable range of the injection pressure of the pump body is 10-70 MPa, and the injection flow range is 5-10L/min.
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