A multilayer horizontal well three-dimensional circulation geothermal exploitation structure and construction method

Abstract

The application discloses a kind of multilayer horizontal well three-dimensional circulation geothermal exploitation structure and construction method, it is related to geothermal resource development application technical field, and the present application is with a water injection well and a production well as a production well group, with a process well is drilled from top to bottom multilayer horizontal branch hole, respectively with water injection well and production well straight well borehole connection, multilayer horizontal circulation structure is cemented with each other by well cementing, and central tube is lowered into water injection well, realizes each layer independent closed circulation geothermal energy resource exploitation.The present application compared with prior art has the characteristics such as high heat exchange efficiency, low construction and operation cost, small floor area, no need to fracture, no induced earthquake, especially suitable for geologic conditions of thick thermal reservoir, can be implemented multilayer radial horizontal circulation structure in a process well, with a group of water injection well and production well form closed circulation, increase heat exchange area, substantially improve heat exchange effect.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of geothermal resource development and application, in particular to a multi-layer horizontal well three-dimensional circulation geothermal exploitation structure and construction method. BACKGROUND

[0002] Geothermal energy, as a clean renewable energy, is widely distributed and can be stably and continuously supplied. Geothermal resources can be divided into shallow geothermal resources, medium-deep geothermal resources, hot dry rock geothermal resources and magma-type geothermal resources according to distribution location and occurrence state. The depth of hot dry rock is generally 3000 meters or more, hot dry rock (hot dry rock) contains no or only a small amount of fluid, and the temperature is higher than 180 DEG C. The thermal energy of hot dry rock can be utilized under current technical and economic conditions. The thermal energy of hot dry rock is stored in various metamorphic or crystalline rock bodies. Common hot dry rocks include biotite gneiss, granite and granodiorite. Hot dry rock development and utilization need to artificially create a heat reservoir, inject low-temperature water into the injection well (recharge well) at high pressure, and make the rock body produce cracks. With the continuous injection of low-temperature water, the cracks increase and expand, and are interconnected, and finally form a roughly planar artificial hot dry rock heat reservoir structure. The injected water moves along the cracks and exchanges heat with the surrounding rock, producing high-temperature high-pressure water or water vapor mixture with a temperature of 200-300 DEG C, which is extracted from the production well. The tail water after use returns to the underground through the injection well, forming a closed loop. Since hot dry rock needs to form a fracture network in the development process, this method has high fracturing cost and uncontrollable fracturing direction, and often induces earthquakes during water injection and fracturing, which is one of the main reasons why hot dry rock has not been commercialized. SUMMARY

[0003] The purpose of the present application is to provide a multi-layer horizontal well three-dimensional circulation geothermal exploitation structure and construction method to solve the problems existing in the prior art, effectively avoid the risk of fracturing-induced earthquake disasters, and greatly reduce the development cost of hot dry rock.

[0004] To achieve the above purpose, the present application provides the following scheme:

[0005] The present application provides a multi-layer horizontal well three-dimensional circulation geothermal exploitation structure, which comprises a process well, an injection well and a production well. The process well comprises at least one horizontal circulation structure.

[0006] Each of the horizontal circulation structures comprises at least one first horizontal well and at least one second horizontal well. One end of the first horizontal well is in communication with the injection well, and one end of the second horizontal well is in communication with the production well. The other end of the first horizontal well of the same horizontal circulation structure is in communication with the other end of the second horizontal well.

[0007] When the horizontal circulation structures are at least two, each of the horizontal circulation structures is arranged from top to bottom, and one end of the first horizontal well of different horizontal circulation structures does not communicate with each other;

[0008] A sealing structure is arranged between the other end of the first horizontal well and the process well and between the other end of the second horizontal well and the process well.

[0009] Preferably, the first horizontal well and the second horizontal well of the same horizontal circulation structure are located at the same horizontal position.

[0010] Preferably, in the vertical direction, the vertical distance between adjacent horizontal circulation structures is 50-150 m.

[0011] Preferably, the distance between the injection well and the production well is greater than 50 m; the distance between the process well and the injection well and the distance between the process well and the production well is 400-600 m.

[0012] Preferably, a plurality of central pipes are arranged in the injection well, each of the central pipes is arranged in a nested manner from inside to outside, the space inside the innermost central pipe is an inner space, the space between adjacent central pipes is an adjacent space, and the space between the outermost central pipe and the injection well is an outer space; the inner space, each adjacent space and the outer space are respectively communicated with one end of the first horizontal well of one horizontal circulation structure.

[0013] Preferably, the number of central pipes is one less than the number of horizontal circulation structures.

[0014] Preferably, the first horizontal well of each horizontal circulation structure is respectively communicated with the inner space, each adjacent space from inside to outside and the outer space from bottom to top one by one.

[0015] The application further provides a construction method of the geothermal exploitation structure of the multi-layer horizontal well three-dimensional circulation, comprising the following steps:

[0016] Step one, injection well, production well, process well well site arrangement;

[0017] Step two, drilling the injection well: according to the heat extraction requirement of the thermal reservoir stratum condition, the wellbore structure of the injection well is designed, first, the injection well is drilled, drilled to the predetermined depth, and then the first surface casing is lowered to cement the well, and after the condensation is completed, the drilling is continued to drill vertically to the thermal reservoir depth, and the bottom is a bare hole section;

[0018] Step three, drilling the production well: according to the heat storage stratum condition and heat extraction requirement, the well structure of the production well is designed, the production well is drilled, and after drilling to the predetermined depth, the drilling is stopped, the second surface casing is lowered to cement the well, and after the completion of the cementation, the drilling is continued to drill vertically to the heat storage depth, and the bottom is a bare hole section;

[0019] Step four, the process well and the injection well are connected through the first horizontal well;

[0020] Step five, the process well and the production well are connected through the second horizontal well;

[0021] Step six, according to the same docking mode, the drill bit is lowered into the process well, and the horizontal drilling is performed downwardly and transversely, the docking of the process well and the injection well and the production well is completed in sequence under the guidance of the target docking guide instrument, and the open hole bridge plug and the cementing plug are lowered at the branch points of each layer;

[0022] Step seven, the central pipe and the packer are lowered in the injection well;

[0023] Step eight, water test operation, water injection is performed from the inside space of the injection well, each adjacent space and the outside space in sequence, the return of the production well is observed, and it is ensured that the horizontal circulation structure of each layer is independently circulated;

[0024] Step nine, process well sealing and backfilling: after the three-dimensional circulation test operation of the multi-layer horizontal circulation structure is normal, the cement slurry is injected from the inside of the process well to the wellhead, and the process well is sealed.

[0025] Preferably, in step four, the process well and the injection well are connected through the first horizontal well, and the process well is drilled, drilled to the predetermined depth, the third surface casing is lowered to cement the well, and after the completion of the cementation, the drilling is continued, the drilling assembly is a drill bit, a magnetic signal generating joint, a screw drill, a non-magnetic drill pipe and a drill pipe in sequence, the non-magnetic drill pipe is internally provided with a while-drilling inclinometer, the first horizontal well is directionally drilled to the injection well according to the design requirement, when the magnetic signal generating joint is 120m away from the wellbore of the injection well, the target docking guide instrument is lowered to the predetermined docking depth from the injection well using the logging cable, the first horizontal well is directionally drilled through the target docking guide instrument, the docking is realized, and after the connection, the downhole drilling assembly of the process well is lifted to the branch well opening depth;

[0026] In the step five, the process that the process well and the production well are connected through the second horizontal well butt joint is as follows: according to the while-drilling inclinometer data, adjusting the screw drill tool face, opening the branch well new hole, according to the design requirement, the directional drilling of the second horizontal well is carried out to the production well direction, when the magnetic signal generating joint is 120 m away from the wellbore of the production well, the medium target butt joint guiding instrument is lowered into the predetermined butt joint depth from the production well by using the logging cable, the directional drilling of the second horizontal well is carried out through the medium target butt joint guiding instrument, the butt joint is realized, after the butt joint is connected, the drilling tool is lifted, the open hole bridge plug is lowered into the process well and the cement slurry is injected, the well is cemented and the branch point upper part to the straight well section bottom is blocked.

[0027] The present application has the following technical effects compared with the prior art:

[0028] The present application takes one injection well and one production well as one production well group, one process well is drilled with multiple horizontal branch holes from top to bottom, which are connected with the injection well and the production well straight well bore respectively, the multiple horizontal circulation structures are cemented and sealed with each other, the central pipe is lowered into the injection well, and the independent closed circulation of each layer is realized to exploit the geothermal energy resources. Compared with the prior art, the present application has the characteristics of high heat exchange efficiency, low construction and operation cost, small land occupation, no need of fracturing and no induced earthquake, and is especially suitable for the geological conditions of thick heat reservoir, and can implement the multiple radial horizontal circulation structure in one process well, and form the closed circulation with one group of injection well and production well, increase the heat exchange area and greatly improve the heat exchange effect. The present application meets the development and utilization of clean geothermal resources, meets the environmental protection and energy saving requirements, and has considerable economic benefit and good social benefit. BRIEF DESCRIPTION OF DRAWINGS

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments will be briefly introduced as follows. Obviously, the drawings in the following description only constitute some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor on the basis of these drawings.

[0030] Figure 1 It is a geothermal exploitation structure diagram of the multi-layer horizontal well three-dimensional circulation of the present application Figure 1

[0031] Figure 2 It is a geothermal exploitation structure diagram of the multi-layer horizontal well three-dimensional circulation of the present application Figure 2

[0032] Figure 3 It is a process well and injection well butt joint diagram of the present application

[0033] Figure 4 It is a process well and production well butt joint diagram of the present application ​​

[0034] Wherein: 1-First surface casing, 2-Second surface casing, 3-Third surface casing, 4-Center casing, 5-Packer, 6-Solid seal structure, 7-First horizontal well, 8-Second horizontal well, 9-Drill bit, 10-Magnetic signal generator connector, 11-Screw drill string, 12-Non-magnetic drill pipe, 13-Measuring while drilling instrument, 14-Drill pipe, 15-Logging cable, 16-Target docking guidance instrument, 17-Inner space, 18-Adjacent space, 19-Outer space, 100-Injection well, 200-Production well, 300-Process well. Detailed Implementation

[0035] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] The purpose of this invention is to provide a multi-layer horizontal well three-dimensional circulation geothermal extraction structure and construction method to solve the problems existing in the prior art, effectively avoid the risk of earthquake disasters induced by fracturing, and greatly reduce the development cost of hot dry rock.

[0037] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0038] Example 1

[0039] like Figures 1 to 4 As shown: This embodiment provides a multi-layer horizontal well three-dimensional circulation geothermal extraction structure, including a process well 300, an injection well 100, and an extraction well 200. The process well 300 includes at least one horizontal circulation structure. The injection well 100 and the extraction well 200 are both vertical wells. The process well 300 is a multi-layer multi-branch horizontal well. The wellhead of the injection well 100 is cemented through a first surface casing 1, and an open hole section is left at the bottom of the injection well 100. The wellhead of the extraction well 200 is cemented through a second surface casing 2, and an open hole section is left at the bottom of the extraction well 200. The wellhead of the process well 300 is cemented through a third surface casing 3. A heat insulation layer is provided on the outer wall of the upper wellhead of the extraction well 200 to reduce heat loss.

[0040] Each horizontal circulation structure comprises at least one first horizontal well 7 and at least one second horizontal well 8, the first horizontal well 7 and the second horizontal well 8 are both horizontally arranged, the first horizontal well 7 and the second horizontal well 8 are both open hole sections, and no casing is arranged in view of good formation stability, one end of the first horizontal well 7 is communicated with the injection well 100, the butt joint section of the injection well 100 and the first horizontal well 7 is an open hole section, one end of the second horizontal well 8 is communicated with the production well 200, and the other end of the first horizontal well 7 of the same horizontal circulation structure is respectively communicated with the other end of the second horizontal well 8;

[0041] When the horizontal circulation structure is at least two, each horizontal circulation structure is arranged from top to bottom, and the one end of the first horizontal well 7 of different horizontal circulation structures is not communicated with each other, so that the horizontal circulation structure of each layer and the straight well section of the injection well 100 and the straight well section of the production well 200 form an independent circulation system.

[0042] The other end of the first horizontal well 7 and the process well 300, and the other end of the second horizontal well 8 and the process well 300 are both provided with a sealing structure 6.

[0043] In the embodiment, the first horizontal well 7 and the second horizontal well 8 of the same horizontal circulation structure are located at the same horizontal position; in the vertical direction, the vertical distance between adjacent horizontal circulation structures is 50-150 m.

[0044] In the embodiment, the distance between the injection well 100 and the production well 200 is greater than 50 m; the distance between the process well 300 and the injection well 100 and the distance between the process well 300 and the production well 200 is 400-600 m.

[0045] In the embodiment, a plurality of center pipes 4 are arranged in the injection well 100, the center pipes 4 are oil pipes, the center pipes 4 are arranged in the injection well 100 in a nested manner from inside to outside, the space inside the innermost center pipe 4 is an inner space 17, the space between adjacent center pipes 4 is an adjacent space 18, and the space between the outermost center pipe 4 and the injection well 100 is an outer space 19, the inner space 17, each adjacent space 18 and the outer space 19 are respectively communicated with one end of the first horizontal well 7 of one horizontal circulation structure.

[0046] In the embodiment, the number of the center pipes 4 is less than the number of the horizontal circulation structures by one.

[0047] In the embodiment, the first horizontal well 7 of each horizontal circulation structure is respectively and correspondingly communicated with the inner space 17, each adjacent space 18 from inside to outside and the outer space 19 from bottom to top.

[0048] The multi-layer horizontal well three-dimensional circulation geothermal exploitation structure of the embodiment takes one injection well 100 and one exploitation well 200 as a production well group, and takes one process well 300 drilled in multiple layers from top to bottom as a horizontal circulation structure. The horizontal circulation structure is connected with the vertical wellbore of the injection well 100 and the vertical wellbore of the exploitation well 200 respectively, and is sealed from each other by cementing. A double-layer tubing is lowered into the injection well 100, the bottom of the outer tubing is sealed from the open hole formation (outer space 19) by the packer 5, and the bottom of the inner tubing is sealed from the outer tubing (adjacent space 18) by the packer 5, so as to finally realize independent closed circulation exploitation of geothermal energy resources in each layer.

[0049] Embodiment two

[0050] The embodiment provides a construction method of the multi-layer horizontal well three-dimensional circulation geothermal exploitation structure of embodiment one, including the following steps.

[0051] Step one, well site arrangement of the injection well 100, the exploitation well 200 and the process well 300: referring to Figure 1 The injection well 100 and the exploitation well 200 are taken as a production well group, the wellhead position interval of the injection well 100 and the exploitation well 200 is above 50 m, and the specific position can be adjusted on the ground surface according to buildings or obstacles. The well interval L1, L2 between the wellhead of the process well 300 and the injection well 100 and the exploitation well 200 is preferably 400-600 m;

[0052] Step two, drilling of the injection well 100: the well structure of the injection well 100 is designed according to the heat extraction requirement of the thermal reservoir formation condition. First, the injection well 100 is drilled, and then the drilling is stopped after drilling to the predetermined depth. The first surface casing 1 is lowered for cementing. After the cementing is completed, the drilling is continued to drill vertically to the thermal reservoir depth, and the bottom is an open hole section.

[0053] Step three, drilling of the exploitation well 200: the well structure of the exploitation well 200 is designed according to the heat extraction requirement of the thermal reservoir formation condition. The exploitation well 200 is drilled, and then the drilling is stopped after drilling to the predetermined depth. The second surface casing 2 is lowered for cementing. After the cementing is completed, the drilling is continued to drill vertically to the thermal reservoir depth, and the bottom is an open hole section.

[0054] Step four, connection of the process well 300 and the injection well 100 through the first horizontal well 7: referring to Figure 3Drilling of process well 300 begins. After reaching the predetermined depth, the drill string is pulled out, and the third surface casing 3 is run in for cementing. After cementing, drilling continues. The drill string assembly consists of drill bit 9, magnetic signal generator connector 10, screw drill string 11, non-magnetic drill pipe 12, and drill pipe 14. The non-magnetic drill pipe 12 is equipped with a drilling rig 13. Directional drilling of the first horizontal well 7 is carried out towards injection well 100 according to design requirements. When the magnetic signal generator connector 10 is approximately 120m away from the wellbore of injection well 100, drilling begins from injection well 100. Within 00, the logging cable 15 is lowered into the target docking guidance instrument 16 to the predetermined docking depth. The first horizontal well 7 is guided to directional drilling through the target docking guidance instrument 16. The drilling trajectory control in this stage is obtained through drilling data. The vertical and horizontal deviations of the drill bit 9 are strictly controlled to achieve docking and connection between the first horizontal well 7 and the vertical section of the water injection well 100. After docking and connection, there will be a return flow at the wellhead of the water injection well 100. The pump is started to circulate and remove the cuttings in the hole. The downhole drilling tool of the process well 300 is raised to the opening depth of the branch well.

[0055] Step 5: The process well 300 and the production well 200 are connected via the second horizontal well 8: See [link / reference] Figure 4 According to the data from the logging-while-drilling instrument 13, the tool face of the screw drill string 11 is adjusted to open a new hole for the branch well. The second horizontal well 8 is then directionally drilled towards the production well 200 according to the design requirements. When the magnetic signal generator connector 10 is 120m away from the wellbore of the production well 200, the target docking guide instrument 16 is lowered from the production well 200 using the logging cable 15 to the predetermined docking depth. The second horizontal well 8 is then directionally drilled using the target docking guide instrument 16 to achieve docking and connection between the second horizontal well 8 and the vertical section of the production well 200. The pump is started to circulate and remove cuttings from the hole. The drill string is then lifted, and an open-hole bridge plug is lowered from the process well 300. Cement slurry is used to form a sealing structure in the process well 300 for sealing and cementing. After cementing, the upper part of the branch point to the bottom of the vertical section is sealed.

[0056] Step 6: Following the same docking method, drill bit 9 is lowered into process well 300 and drilled vertically downwards through the hole to carry out the construction of the horizontal circulation structure of each layer. Under the guidance of the target docking guide instrument 16, process well 300 is docked with water injection well 100 and production well 200 in sequence, and open hole bridge plugs and cementing are installed at the branch points of each layer.

[0057] Step 7: Lower the central pipe 4 and packer 5 from the wellhead of injection well 100;

[0058] Step 8: Water supply test run. Water is injected sequentially from water inlet ①, water inlet ② and water inlet ③ of water injection well 100. The return flow of water from well 200 is observed to ensure that the horizontal circulation structure of each layer is an independent circulation.

[0059] Step nine, the process well 300 is sealed and backfilled: in order to avoid excessive occupation of land resources, after the multi-layer horizontal circulation structure is normally operated, the process well 300 is sealed by injecting cement slurry into the well mouth. In this way, the three-dimensional circulation geothermal exploitation under different exploitation modes can be realized, and the features of large heat extraction area, small surface area, high heat exchange efficiency, and low construction cost are achieved.

[0060] The multi-layer horizontal well three-dimensional circulation geothermal construction method of the embodiment takes one injection well 100 and one production well 200 as one production well group, and takes one multi-layer multi-branch horizontal well as a process well 300. The injection well 100 and the production well are straight wells. First, the injection well 100 is drilled, and then the first surface casing 1 is lowered into the well. The well bottom is left as a bare hole section. Then, the production well 200 is drilled, and then the second surface casing 2 is lowered into the well. The well bottom is left as a bare hole section. Then, the straight well section of the process well 300 is drilled, and then the third surface casing 3 is lowered into the well. Then, the first horizontal well 7 is drilled in the direction of the injection well 100. The magnetic signal generating joint 10 is connected between the horizontal well drilling bit 9 and the screw drill 11. When the magnetic joint is about 120 m away from the wellbore of the injection well 100 in a straight line, the center target butt joint guiding instrument 16 is lowered into the injection well 100 to a predetermined depth. The first horizontal well 7 is guided to be connected with the straight well of the injection well 100 by the center target butt joint guiding instrument 16. After the connection, the first horizontal well 7 is raised to the build-up section, the drilling tool posture is adjusted, a new hole is opened, and the second horizontal well 8 is drilled in the direction of the production well 200. When the magnetic joint is about 120 m away from the wellbore of the production well 200 in a straight line, the center target butt joint guiding instrument 16 is lowered into the production well 200 to a predetermined depth. The second horizontal well 8 is guided to be connected with the straight well of the injection well 100 by the center target butt joint guiding instrument 16. After the connection, the downhole drilling bit 9 is raised. The bare hole bridge plug is lowered at the branch point of the first horizontal well 7 and the second horizontal well 8. The cement slurry is used to seal and cement the vertical section of the process well 300. After the cement is cured, the drilling tool is lowered, the through hole is drilled to the bottom to different depths to form directional build-ups, and the three-layer horizontal branch wells are sequentially connected with the injection well 100 and the production well 200. After the downhole drilling tool of the process well 300 is raised, the process well 300 is sealed and cemented by using the cement slurry, and the process well 300 is restored to the ground. The inner and outer two-layer center pipes 4 and the packer 5 are lowered into the injection well 100. After the cold water is injected from different injection openings of the injection well 100, the vertical circulation well group can realize independent circulation and heat extraction of each layer.

[0061] Application example

[0062] Technical requirements:

[0063] The wellbore structure of the injection well 100: the first opening well diameter is Φ311.1 mm, the Φ244.5 mm surface casing is lowered into the well for 1200 m cementing; the second opening well diameter is Φ215.9 mm, the drilling depth is 2000 m, and the well is completed as a bare hole.

[0064] The wellbore structure of the exploitation well 200: the first drilling has a diameter of Φ311.1mm, and a Φ244.5mm surface casing is lowered for cementing for 1200m; the second drilling has a diameter of Φ215.9mm, and the drilling depth is 2100m, and the well is completed as a bare hole.

[0065] The wellbore structure of the process well 300: the first drilling has a diameter of Φ311.1mm, and a Φ244.5mm surface casing is lowered for cementing for 1200m, and is connected with the water injection well 100 with a horizontal displacement of 500m, and the drilling direction is 0°, and is connected with the exploitation well 200 with a horizontal displacement of 526m, and the drilling direction is 20°.

[0066] The specific construction steps are as follows:

[0067] Step one, according to the block geological data, the wellbore structure is designed, and the wellhead positions of the water injection well 100, the exploitation well 200 and the process well 300 are selected, wherein the wellhead distance between the process well 300 and the water injection well 100 is 500m, the wellhead distance between the process well 300 and the exploitation well 200 is 526m, and the wellhead distance between the water injection well 100 and the exploitation well 200 is 146m;

[0068] Step two, the water injection well 100 is drilled in one drilling, the drilling diameter is Φ311.1mm, the drilling depth is 1200m, a Φ244.5mm surface casing is lowered for cementing, and the cement slurry returns to the ground surface; the water injection well 100 is drilled in two drilling, the drilling diameter is Φ215.9mm, the vertical drilling is performed to 2000m for well completion, the mud is circulated, and the eye is reversed after drilling;

[0069] Step three, the exploitation well 200 is drilled in one drilling, the drilling diameter is Φ311.1mm, the drilling depth is 1200m, a Φ244.5mm surface casing is lowered for cementing, and the cement slurry returns to the ground surface; the exploitation well 200 is drilled in two drilling, the drilling diameter is Φ215.9mm, the vertical drilling is performed to 2100m for well completion, the mud is circulated, and the eye is reversed after drilling;

[0070] Step four, when the process well 300 is drilled, the drilling hole diameter is Φ311.1mm, the drilling depth is 1200m, Φ244.5mm surface casing is lowered and cementing is performed, and the cement slurry returns to the ground surface; the second drilling is performed, the drilling hole diameter is Φ215.9mm, vertical drilling is performed to 1500m, and then the directional build-up is performed to the wellbore of the injection well 100, the build-up drilling dogleg is 6° / 30m, the horizontal section is entered at 1950m, and when the drilling is performed to 2040m, the middle target butt joint guiding instrument 16 is lowered from the injection well 100 wellhead through the armored cable connection logging winch, the middle target butt joint guiding instrument 16 is lowered to a depth of 1736m, the process well 300 continues the directional drilling of the horizontal well, in the drilling process, a dynamic magnetic field is generated by the rotating magnetic joint, the middle target butt joint guiding instrument 16 in the non-magnetic drill pipe 12 of the injection well 100 receives the magnetic signal and then performs positioning analysis on the position of the magnetic joint, the directional well engineer performs directional correction according to the deviation result, the magnetic guiding instrument in the process well 300 is pulled out, the process well 300 continues to drill, until the mud returns in the injection well 100, the first horizontal well 7 (C-A-1) of the process well 300 is connected with the injection well 100, and the butt joint depth is 1736m;

[0071] Step five, the drilling tool in the process well 300 is lifted to 1700m, the drilling tool is adjusted clockwise according to the gravity tool face data of the MWD instrument to perform directional drilling of the second horizontal well 8 (C-B-1) horizontal branch hole, the horizontal section is entered at 2050m, and when the drilling is performed to 2100m, the middle target butt joint guiding instrument 16 is lowered from the production well 200 to 1863m, the process well 300 continues to drill, until the mud returns in the production well 200, the second horizontal well 8 (C-B-1) of the process well 300 is connected with the production well 200, and the butt joint depth is 1863m;

[0072] The drilling tool in the process well 300 is pulled out, the bridge plug is lowered to about 1550m, the cement slurry is injected from the process well 300 to cement the bridge plug above, and the cement slurry liquid level depth is about 1480m;

[0073] Step six, after the cementing is cured, the heavy drill pipe is lowered to sweep the plug, the vertical drilling is performed after the bottom hole is probed, the directional build-up is performed when the vertical drilling is performed to 1600m, the butt joint of the first horizontal well 7 (C-A-2) of the process well 300 with the injection well 100 and the butt joint of the second horizontal well 8 (C-B-2) of the process well 300 with the production well 200 are sequentially completed; the drilling tool in the process well 300 is pulled out, the bridge plug is lowered to about 1650m, the cement slurry is injected from the process well 300 to cement the bridge plug above, and the cement slurry liquid level depth is about 1580m;

[0074] After the cementing, the drilling is continued to complete the connection of the first horizontal well 7 (C-A-3) of the process well 300 with the injection well 100 and the connection of the second horizontal well 8 (C-B-3) with the production well 200; the drilling tools in the process well 300 are pulled out, a bridge plug is lowered to about 1750 m, and the cement slurry is injected from the process well 300 to cement the above bridge plug, and the surface equipment of the process well 300 is removed;

[0075] Step seven, a 41 / 2" tubing is lowered from the injection well 100, the drilling tool assembly is 41 / 2" tubing+ bypass joint+ 41 / 2" tubing+ open hole packer+ 41 / 2" tubing, the open hole packer is ensured to be lowered to between the first connection point 1736 m and the second connection point 1836 m through the lengthening of the drilling tool, and after the completion of the lowering of the 41 / 2" tubing drilling tool assembly, the wellhead is hung, and the open hole packer is set by lowering the setting pipe string;

[0076] A 27 / 8" tubing is lowered from the 41 / 2" tubing, a casing packer is connected at the bottom of the tubing, the packer is ensured to be lowered to between the 41 / 2" bypass joint and the bottom 41 / 2" tubing through the lengthening, the 27 / 8" tubing is lowered to completion, the wellhead is hung, and the packer 5 is inflated and sealed;

[0077] Step eight, clear water is pumped through the three injection ports of the injection well respectively, the return of the production well 200 is observed, and it is ensured that each layer can be independently circulated and produced;

[0078] Step nine, the process well 300 is sealed and backfilled: after the multi-layer horizontal circulation structure is normally operated, the cement slurry is injected from the inside of the process well 300 to the wellhead, and the process well 300 is sealed.

[0079] The principles and implementation manners of the present application are described in the specification by using specific examples, and the above description of the examples is only used to help understand the method of the present application and its core idea; meanwhile, for those skilled in the art, according to the idea of the present application, the specific implementation manners and application ranges will be changed. In conclusion, the content of the specification should not be understood as a limitation of the present application.

Claims

1. A multi-layer horizontal well three-dimensional circulation geothermal extraction structure, characterized in that: It includes process wells, injection wells and production wells, wherein the process well includes at least one horizontal circulation structure; Each of the horizontal circulation structures includes at least one first horizontal well and at least one second horizontal well. One end of the first horizontal well is connected to the water injection well, and one end of the second horizontal well is connected to the production well. The other end of the first horizontal well in the same horizontal circulation structure is connected to the other end of the second horizontal well. When there are at least two horizontal circulation structures, each horizontal circulation structure is arranged from top to bottom, and one end of the first horizontal well of different horizontal circulation structures is not connected to each other. A solid sealing structure is provided between the other end of the first horizontal well and the process well, and between the other end of the second horizontal well and the process well; The water injection well is provided with a number of central pipes, which are nested from the inside to the outside. The space inside the innermost central pipe is called the inner space, the space between adjacent central pipes is called the adjacent space, and the space between the outermost central pipe and the water injection well is called the outer space. The inner space, each of the adjacent spaces and the outer space are respectively connected to one end of the first horizontal well of the horizontal circulation structure.

2. The multi-layer horizontal well three-dimensional circulation geothermal extraction structure according to claim 1, characterized in that: The first horizontal well and the second horizontal well of the same horizontal circulation structure are located at the same horizontal position.

3. The multi-layer horizontal well three-dimensional circulation geothermal extraction structure according to claim 1, characterized in that: In the vertical direction, the vertical distance between adjacent horizontal circulation structures is 50~150m.

4. The multi-layer horizontal well three-dimensional circulation geothermal extraction structure according to claim 1, characterized in that: The distance between the injection well and the extraction well is greater than 50m; The distance between the process well and the water injection well, and the distance between the process well and the production well, are 400-600m.

5. The multi-layer horizontal well three-dimensional circulation geothermal extraction structure according to claim 1, characterized in that: The number of central tubes is one less than the number of horizontal circulation structures.

6. The multi-layer horizontal well three-dimensional circulation geothermal extraction structure according to claim 1, characterized in that: Each of the first horizontal wells of the horizontal circulation structures is connected from bottom to top to the inner space, each of the adjacent spaces from the inside to the outside, and the outer space.

7. A construction method for a multi-layer horizontal well three-dimensional circulation geothermal extraction structure according to any one of claims 1-6, characterized in that: Includes the following steps: Step 1: Layout of injection wells, production wells, and process wells; Step 2, Drilling the water injection well: Design the wellbore structure of the water injection well according to the heat recovery requirements of the geothermal reservoir. First, start drilling the water injection well. After drilling to the predetermined depth, pull out the drill string and run in the first surface casing for cementing. After cementing is completed, continue drilling vertically to the geothermal reservoir depth. The bottom is the open hole section. Step 3, Drilling the production well: Design the wellbore structure of the production well according to the heat recovery requirements of the geothermal reservoir, and start drilling the production well. After drilling to the predetermined depth, pull out the drill string and run in the second surface casing for cementing. After cementing is completed, continue drilling vertically to the geothermal reservoir depth. The bottom is the open hole section. Step four: The process well and the injection well are connected via the first horizontal well; Step 5: The process well and the production well are connected via a second horizontal well; Step 6: Following the same docking method, the drill bit is lowered into the process well and drilled vertically downwards through the hole to carry out the construction of the horizontal circulation structure of each layer. Under the guidance of the center target docking guidance instrument, the docking of the process well with the water injection well and the production well is completed in sequence, and the open hole bridge plug and cementing are installed at the branch points of each layer. Step 7: Install the center pipe and packer in the injection well; Step 8: Water supply test run. Water is injected sequentially from the inner space of the injection well, each adjacent space, and the outer space. The return flow from the extraction well is observed to ensure that the horizontal circulation structure of each layer is an independent circulation. Step 9, sealing and backfilling the process well: After the multi-layer horizontal circulation structure has been tested and is running normally, cement slurry is injected from inside the process well to the wellhead to seal the process well.

8. The construction method of the multi-layer horizontal well three-dimensional circulation geothermal extraction structure according to claim 7, characterized in that: In step four, the process well and the injection well are connected through the first horizontal well as follows: Drilling begins in the process well. After drilling to the predetermined depth, the well is pulled out and the third surface casing is run in for cementing. After cementing is completed, drilling continues. The drill string assembly consists of a drill bit, a magnetic signal generator connector, a screw drill string, a non-magnetic drill pipe, and a drill rod. The non-magnetic drill pipe is equipped with a drilling rig. The first horizontal well is directionally drilled in the direction of the injection well according to the design requirements. When the magnetic signal generator connector is 120m away from the wellbore of the injection well, a target docking guide instrument is run from the injection well using a logging cable to the predetermined docking depth. The first horizontal well is directionally drilled through the target docking guide instrument to achieve docking. After docking and connection, the downhole drill string of the process well is pulled up to the opening depth of the branch well. In step five, the process of connecting the process well and the production well through the second horizontal well is as follows: According to the data from the logging-while-drilling instrument, the tool face of the screw drill is adjusted to open a new hole for the branch well. The second horizontal well is directionally drilled in the direction of the production well according to the design requirements. When the magnetic signal generating connector is 120m away from the wellbore of the production well, a center target docking guide instrument is lowered from the production well using a logging cable to the predetermined docking depth. The second horizontal well is directionally drilled through the center target docking guide instrument to achieve docking. After docking and connection, the drill string is lifted, and an open hole bridge plug is lowered from the process well and cement slurry is injected. The well is cemented and the top of the branch point to the bottom of the vertical section is sealed.

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