WO2016082188A1

WO2016082188A1 - Hot dry rock multi-cycle heating system and production method therefor

Info

Publication number: WO2016082188A1
Application number: PCT/CN2014/092490
Authority: WO
Inventors: 张延军; 张佳宁; 白林; 郭亮亮; 李正伟; 于子望; 胡忠君; 许天福
Original assignee: 吉林大学
Priority date: 2014-11-28
Filing date: 2014-11-28
Publication date: 2016-06-02

Abstract

A hot dry rock multi-cycle heating system and a production method therefor. An injection well (1) and a production well (2) are drilled downwards from the ground; a first heat exchange channel (6) and second heat exchange channels (11) are obtained by manual fracturing at different depths of hot dry rock and are in a fracture swarm mode; water that is injected from the injection well (1) at least flows through the first heat exchange channel (6) and the second heat exchange channels (11) and then is drained out from the production well (2), and thus the heating process including at least two heating cycles is completed through one-time water injection and at least two times of heat exchange at different depths. Compared with the existing one-time cycling, the system does not have site requirements, repeated water injection and extraction are needless, operation is simple, and the utilization rate of the hot dry rock thermal energy is greatly improved.

Description

Dry hot rock multi-cycle heating system and production method thereof

Technical field

The invention relates to a thermal energy conversion system and a production method thereof, which utilize the thermal energy in the deep underground and obtain the geothermal energy through heat exchange, in particular, the dry heat rock multi-cycle heating system and the production method thereof.

Background technique

With the development of the economy and the improvement of people's living standards, energy and environmental issues have increasingly become the subject of human concern. Among them, dry hot rock is a kind of clean energy buried deep underground, and its heat is very rich, but it has been Not exploited on a large scale.

At present, domestic medium-deep geothermal energy mining technology is not mature, and reports on multiple-cycle heating have not been found, and there are few reports on artificial fracturing technology. In the world, the single-cycle method is commonly used to obtain geothermal energy, which has defects such as low geothermal energy acquisition rate and low utilization rate.

For example, WO 2012/173916 A1 discloses a system utilizing geothermal energy, the system comprising a production casing and a production pipe located in the production casing. An annular space is formed between the production casing and the production pipe, and the sealing space is provided in the annular space. The system uses a single well operation, the temperature after heating is often not met, and the utilization rate of geothermal energy is low.

US 2013/112402 A1 discloses a geothermal well forming method having a first section, a second section and an arcuate section connecting the first section and the second section to each other. The geothermal well is circulated and heated in the underground, and there are also defects such as "the temperature after heating is often not up to the requirement, and the utilization rate of geothermal energy is low".

Summary of the invention

The object of the present invention is to provide a dry hot rock multi-cycle heating system and a production method thereof according to the defects in the prior art described above, which can make water and dry by using at least two heating cycles in the case of single water injection. The hot rock undergoes multiple heat exchanges, thereby significantly increasing the geothermal energy utilization rate and heat exchange efficiency.

To this end, according to one aspect of the invention, a dry hot rock multi-cycle heating system is provided, comprising:

Injection well

Production well

a fluid passageway in fluid communication with the injection well and the production well, respectively, at a depth relative to the ground;

a first heat exchange passage formed in the underground dry hot rock and at a first depth relative to the ground, the first heat exchange passage being in fluid communication with the injection well and the production well, respectively;

a second heat exchange passage formed in the underground dry hot rock and at a second depth relative to the ground, the second heat exchange passage being in fluid communication with the injection well and the production well, respectively;

a packer consisting of a packing member disposed in the injection well and the production well, respectively;

a water pump, which is disposed in the production well;

Wherein the water injected from the injection well is allowed to be discharged from the production well via the water suction pipe after sequentially flowing through the fluid passage, the first heat exchange passage, and the second heat exchange passage, thereby passing A single water injection and at least two different depths of heat exchange complete the heating process including at least two heating cycles,

The second depth is greater than the first depth, and the certain depth is less than the first depth and the second depth.

Advantageously, each of said first heat exchange passage and said second heat exchange passage is comprised of a natural fracture group or an artificial fracture group extending between said injection well and said production well.

Advantageously, the artificial fracture group can be formed by a manual fracturing method such as a hydraulic fracturing method or an explosion fracture method.

Advantageously, to achieve a desired heat exchange effect, the first depth is set to 3000 meters and the second depth is set to 4000 meters.

Advantageously, the fluid passage is formed by an artificial fracture group formed by a hydraulic fracturing method or an explosion fracture method or formed by a borehole (preferably formed by an artificial fracture group) in which the fluid passage is located Extending between the production wells, the certain depth is 100-300 meters.

Advantageously, the injection well and the production well are arranged parallel to each other with a horizontal distance between 500 and 700 meters.

Advantageously, the injection well and the production well comprise a vertical section and a horizontal section, respectively, the first heat exchange passage being in a vertical section of the injection well and a vertical section of the production well Extending between the segments, the second heat exchange passage extends between a horizontal section of the injection well and a horizontal section of the production well.

Advantageously, said second heat exchange passage is a horizontal section formed in said injection well and said A horizontal fracture group between horizontal sections of the production well having a horizontal distance from a vertical section of the injection well and a vertical section of the production well of at least 500 meters.

Advantageously, the dry hot rock multi-cycle heating system further comprises a casing disposed at a side wall of the vertical section of the injection well and a side wall of the vertical section of the production well, respectively The packer includes a packer disposed in a vertical section of the injection well and a vertical section of the production well, the fluid passage being disposed in a vertical section of the injection well and the Between the vertical sections of the production well, thereby forming such that water injected from the injection well returns after passing through the fluid passage, the vertical section of the production well, the first heat exchange passage A fluid path into the vertical section of the well.

Advantageously, the pumping pipe is disposed in a vertical section of the production well, the packing device comprising a first and second compartments disposed in a vertical section of the injection well a third packing member and a fourth packing member disposed in a vertical section of the production well, the water suction pipe extending through the third packing member and the fourth packing member, And forming a flow annulus between the casing in the vertical section of the production well and the suction pipe, the fluid passage extending above the first heat exchange passage, the first packing member Separating the vertical section of the injection well into an upper zone, a middle zone and a lower zone with the second packing, the third packing and the fourth packing will be of the production well The vertical section is divided into an upper zone, a middle zone and a lower zone, the water injected from the injection well allowing passage through the upper zone of the vertical section of the injection well, the fluid passage, the vertical of the production well a central portion of the straight section and the first heat exchange passage reaching a lower region of the vertical section of the injection well, And then through the second heat exchanger passage, the suction pipe is discharged from a lower region of the production well back vertical section through the production well.

Advantageously, the first packer is disposed 10-20 meters below the fluid passage, and the second packer is disposed 10-20 meters above the first heat exchange passage, The third packing member is disposed 10-20 meters above the fluid passage, and the fourth packing member is disposed 10-20 meters below the first heat exchange passage.

According to another aspect of the present invention, a method of producing a dry hot rock multi-cycle heating system is provided, comprising the steps of:

Drilling wells and production wells from the ground vertically downwards;

Stop drilling when the injection well and the production well are drilled to a certain depth, respectively, and generate fluid passages respectively in fluid communication with the injection well and the production well by horizontal drilling or manual fracturing techniques;

Continuing to drill the injection well and the production well to the first depth, respectively, and fracturing in the underground dry hot rock by artificial fracturing technology, respectively, in fluid communication with the injection well and the production well First heat exchange passage;

Continuing to drill the injection well and the production well separately to the second depth to stop vertical drilling, ending the vertical section of the injection well and the vertical section of the production well, starting Horizontal drilling to create horizontal sections of the injection well and horizontal sections of the production well that are parallel to each other in the underground dry hot rock;

Stop drilling after drilling a certain distance horizontally, and fracturing a second heat exchange channel respectively in fluid communication with the injection well and the production well by a manual fracturing technique;

Inserting a casing into the injection well and the production well, respectively;

Providing a packing member in the casing of the injection well and the production well, respectively, and providing a water suction pipe in the casing of the production well such that water injected from the injection well is allowed to flow through the The fluid passage, the first heat exchange passage, and the second heat exchange passage are discharged from the production well via the water suction pipe.

According to the method of the invention, it is advantageous if the first depth is 3000 meters and the second depth is 4000 meters.

According to the method of the present invention, it is advantageous that the fluid passage is an artificial fracture group formed by a hydraulic fracturing method or an explosion fracture method, the certain depth being 100 to 300 meters.

According to the method of the invention, it is advantageous if the horizontal distance between the injection well and the production well is between 500 and 700 meters.

According to the method of the invention, it is advantageous if the certain distance is at least 500 meters.

According to the method of the invention, it is advantageous if the sleeve is only arranged in the vertical section of the injection well and in the vertical section of the production well.

According to the method of the invention, it is advantageous if the step of providing a packer comprises providing a first packer and a second packer in a vertical section of the injection well and a vertical zone in the production well a third spacer and a fourth spacer are disposed in the segment, the first spacer is disposed at a lower portion of the fluid passage 10-20 meters, and the second spacer is disposed at the first replacement 10-20 meters at the upper portion of the hot aisle, the third packing member is disposed 10-20 meters above the fluid passage, and the fourth packing member is disposed at a lower portion 10 of the first heat exchange passage -20 meters.

According to the method of the present invention, it is advantageous that the water suction pipe extends through the third and fourth packing members, the casing in the vertical section of the production well and the pumping Water pipe structure Flowing water annulus.

The dry hot rock multi-cycle heating system of the present invention and the production method thereof can overcome the defects of the prior art described above, and can achieve the following significant beneficial effects:

The dry hot rock multi-cycle heating system of the present invention is such that the injected water (temperature, for example, T ₀ ) undergoes a heat exchange with the dry hot rock when flowing through the first depth (for example, 3000 m) (the temperature rises, for example, to T ₁ ), then a high energy utilization system that again exchanges heat with dry hot rock (temperature rises to T ₂ ) as it flows through a second depth (eg, 4000 meters). The invention solves the problem that the geothermal energy acquisition rate and the utilization rate are low for a long time, that is, it adopts multiple cycles (at least two cycles) under a single injection in different depths of the underground, and improves the injection water and the dry hot rock. Utilization of heat exchange. Compared with the previous single cycle, the present invention does not improve the requirements of the site, nor does it greatly increase the difficulty of the technology. The invention does not need to be injected and extracted multiple times (for example, twice), and is simple and convenient to use, and has low production cost and remarkable work efficiency. The invention greatly improves the utilization rate of the dry heat thermal energy and improves the practicality of the dry hot rock by at least two heat exchanges of different depths. In addition, the production method of the dry heat rock multi-cycle heating system of the present invention is simple, convenient, and economical.

DRAWINGS

The invention will be described in more detail below with reference to the drawings and embodiments illustrated by way of example.

1 is a schematic structural view of a dry hot rock multi-cycle heating system according to an embodiment of the present invention;

Figure 2 shows the flow direction of the dry hot rock multi-cycle heating system of Figure 1.

detailed description

1 is a schematic view showing the structure of a dry hot rock multi-cycle heating system according to an embodiment of the present invention.

As shown in FIG. 1, the dry heat rock multi-cycle heating system of this embodiment of the present invention mainly comprises an injection well 1, a production well 2, a fluid passage 5, a first heat exchange passage 6, and a second heat exchange passage 11.

The horizontal distance between the injection well 1 and the production well 2 can be set to be about 500-700 meters. Injection well 1 and production well 2 comprise a vertical section and a horizontal section, respectively. A sleeve 3 is respectively provided at the side wall of the vertical section, and there is no sleeve in the horizontal section.

The fluid channel 5 extends between a vertical section of the injection well 1 and a vertical section of the production well 2, which is in fluid communication with the injection well 1 and the production well 2 and at a depth of approximately 100-300 meters with respect to the ground. . According to this embodiment, the fluid passage 5 is constructed of a group of artificial fractures that can be formed by various manual fracturing methods known in the art, such as existing hydraulic fracturing or burst crushing. Of course, as previously mentioned, the fluid passage 5 can also be formed by a bore.

The first heat exchange passage 6 is formed in the underground dry hot rock, which is at a first depth with respect to the ground and extends between the vertical section of the injection well 1 and the vertical section of the production well 2. According to this embodiment, the first heat exchange passage 6 is composed of an artificial fracture group, which can be formed, for example, by a hydraulic fracturing method or an explosion fracture method. Of course, as previously mentioned, the first heat exchange passage 6 can also be composed of a natural fracture group. The first heat exchange passage 6 is in fluid communication with the injection well 1 and the production well 2, respectively.

The second heat exchange passage 11 is formed in the underground dry hot rock, which is at a second depth with respect to the ground and extends between the horizontal section of the injection well 1 and the horizontal section of the production well 2. The horizontal distance between the second heat exchange passage 11 and the vertical section of the injection well 1 and the vertical section of the production well 2 is at least 500 meters. According to this embodiment, the second heat exchange passage 11 is constituted by an artificial fracture group which is formed, for example, by a hydraulic fracturing method or an explosion fracture method. Of course, as previously mentioned, the second heat exchange passage 11 can also be composed of a natural fracture group. The second heat exchange passage 6 is in fluid communication with the injection well 1 and the production well 2, respectively.

Refer to the existing dry hot rock well, which has a general depth of about 4,000 meters. Further, in the above-described dry hot rock multi-cycle heating system of the present invention, heat exchange is typically performed by a two-layer artificial fracture group formed, for example, by a hydraulic fracturing technique. Considering that the hydraulic fracturing technology has a large range of influences, small laws, and uncertain directionality, there should be a certain distance between the two layers of artificial fracture groups. However, the closer to the ground, the lower the temperature of the rock mass. If the above distance is too large, the heating effect will be reduced. To this end, according to the above embodiment of the invention, the first depth is designed to be approximately 3000 meters and the second depth is designed to be approximately 4000 meters.

The hot rock multi-cycle heating system further includes a packing device and a pumping pipe 4, the packing device including a first packing member 7 and a second packing member 8 disposed in a vertical section of the injection well 1 and a third packer 9 and a fourth packer 10 disposed in a vertical section of the production well 2, the pumping pipe 4 passing through the third packer 9 and the fourth packer 10 Extending in the vertical section of the production well 2, and forming a flow annulus between the casing 3 in the vertical section of the production well 2 and the suction pipe 4. Preferably, the first packing member 7 is disposed 10-20 meters below the fluid passage 5, and the second packing member 8 is disposed 10-20 meters above the first heat exchange passage 6, the third packing member 9 Set at the upper 10-20 meters of the fluid passage 5, the fourth packing member 10 is disposed 10-20 meters below the first heat exchange passage 6. At the office.

The packers of the present invention can be made by existing packer techniques known in the art. For example, if you need to adapt to higher temperatures, you can use reinforced concrete sealing technology: that is, after the casing is lowered into the well, the steel bars are erected and the concrete is poured; if quick and convenient performance is considered, the stone sealing technology can be used. : that is, the rock body corresponding to the caliper is made and placed in the sealing position, and then the concrete seal is poured; or the rubber can be sealed, for example, a special rubber sleeve is arranged on the outer side of the relevant component, and the water is automatically injected after the water is injected. Expanding, thereby achieving the desired containment. Obviously, those skilled in the art can freely choose a suitable isolation technology according to experience and actual needs, and details are not described herein again.

With the above structural design of the present invention, the first packing member 7 and the second packing member 8 divide the vertical section of the injection well 1 into an upper region, a middle region and a lower region, and a third packing member 9 and a fourth portion The packer 10 divides the vertical section of the production well 2 into an upper zone, a middle zone and a lower zone. In this case, the water injected from the injection well 1 may sequentially pass through the upper region of the vertical section of the injection well 1, the fluid passage 5, the central portion of the vertical section of the production well 2, and the first heat exchange passage 6 to the injection. The lower region of the vertical section of the well 1 and then through the second heat exchange passage 11, the lower region of the vertical section of the production well 2, is discharged from the production well 2 via the water suction pipe 4.

The casing 3 of the present invention can be disposed in sections in the injection well 1 and the production well 2. The fluid passage 5, the portion of the first heat exchange passage 6 that is in contact with the injection well 1 and the production well 2 may not be provided with a casing. Alternatively, an outlet opening to the fluid passage 5 is provided in the side wall of the casing 3 in the injection well 1, and a filtering means may be provided at the outlet to prevent the inflow of impurities such as sand.

In connection with Figure 2, the dry hot rock multi-cycle heating system of the present invention can be used, for example, as follows:

First, install pumping equipment at the wellhead of production well 2;

Water is injected into the injection well 1 at a temperature of, for example, T ₀ . Due to the barrier of the first packing member 7 in the injection well 1, water flows through the fluid passage 5 into the flowing water between the casing 3 of the production well 2 and the suction pipe 4. Annulus

The water flows downward in the flowing water annulus of the production well 2, since the barriers of the third packing member 9 and the fourth packing member 10 of the production well 2 flow through the first heat exchange passage 6 and then flow into the injection well 1, Therefore, the water temperature rises to T ₁ and the first heating cycle is completed;

In a water injection well, through the second heat exchange passage 11 into the production well by a horizontal section of the vertical section 2 is a horizontal section flows, the temperature rises again to T _2, then water from the horizontal section of the well production flow 2 Up to the vertical section, through the barrier of the fourth packing 10 in the production well 2, the water flows into the water suction pipe 4 to complete the second heating cycle;

Finally, water is withdrawn from the wellhead of production well 2 by pumping equipment.

Obviously, the dry hot rock multi-cycle heating system according to the present invention is a high-energy utilization system in which the injected water (temperature T ₀ ) flows through the first heat exchange passage 6 for the first heat exchange with the dry hot rock (temperature Raising to T ₁ ), completing the first heating cycle, and then performing heat exchange with the dry hot rock (temperature rises to T ₂ ) while flowing through the second heat exchange passage 11 to complete the second heating cycle. The first heat exchange passage 6 is located approximately 3,000 meters below ground, wherein the dry hot rock temperature is approximately 120 °C. The second heat exchange passage 11 is located approximately 4000 meters underground and the dry hot rock temperature is approximately 160 °C. It has been empirically estimated that the temperature of the withdrawn water is approximately 60-80 ° C by the above two heat exchanges.

The dry hot rock multi-cycle heating system according to the above embodiment of the present invention can be produced by the following method, which comprises the following steps:

The injection well 1 and the pumping well 2 are drilled vertically from the ground, and the horizontal distance between the injection well 1 and the pumping well 2 is about 500-700 meters;

When the injection well 1 and the pumping well 2 are drilled to about 100-300 meters, respectively, the drilling is stopped, and the fluid passage (ie, the upper fracture group) 5 passing through the two wells is fractured by a manual fracturing technique (preferably hydraulic pressure technology);

Continue to drill to about 3000 meters to stop drilling, and then fracture the first heat exchange channel (ie, the lower crack group) 6 through the two wells by manual fracturing technology;

Continue to drill to about 4,000 meters to stop vertical drilling, change to horizontal drilling, horizontal drilling at least 500 meters to stop drilling, and again through the artificial fracturing technology to fracture out the second heat exchange channel through the two wells (ie horizontal crack Group)11;

The casing 3 is lowered into the injection well 1 and the pumping well 2, respectively, and the second packer 8 is disposed at the upper 10-20 meters of the first heat exchange passage 6 in the casing 3 of the injection well 1 in the fluid passage a first packer 7 is disposed at a lower portion of 10 to 10-20 meters;

A fourth packer 10 is disposed 10-20 meters below the first heat exchange passage 6 in the casing 3 of the pumping well 2, and a third packer 9 is disposed 10-20 meters above the fluid passage 5. ;

A water suction pipe 4 is provided in the casing 3 of the vertical section of the pumping well 2, the water suction pipe 4 passes through the third packer 9 and the fourth packer 10, and a water flow is formed between the casing 3 and the water suction pipe 4. Annulus.

Specific examples of the above-described dry hot rock multi-cycle heating system according to the present invention are given below.

Example 1

Two injection wells 1 and 2, which are parallel to each other and 500 meters apart, are drilled on the surface. Note Well 1 and production well 2 will include vertical and horizontal sections, respectively. The vertical section of injection well 1 and production well 2 has a depth of 4000 meters and the horizontal section has a length of 500 meters. The wall of the vertical section of the injection well 1 and the production well 2 are both sleeves 3 of the same material, and a suction pipe 4 is provided in a vertical section inside the casing 3 of the production well 2.

The first drilling depth of the injection well 1 and the production well 2 is 100 meters, and then hydraulic fracturing is simultaneously performed at the bottom of the injection well 1 and the production well 2 to obtain a fluid passage (upper fracture group) 5.

After the first fracturing is completed, the injection well 1 and the production well 2 respectively continue to drill to a depth of 3000 m to stop drilling, and a second hydraulic fracturing to obtain the first heat exchange channel (lower fracture group) ) 6. Then continue to drill the borehole and continue to drill to 4000 meters to change to horizontal drilling, keep the two wells parallel, drill the length of 500 meters to stop drilling, and carry out the third hydraulic fracturing to obtain the second heat exchange channel (horizontal crack group) )11.

In order to achieve a secondary heating cycle (double cycle), a first packing member 7 and a second packing member 8 are provided in the injection well 1, and a third packing member 9 and a fourth partitioning are provided in the production well 2 Item 10. The first spacer 7 is disposed 10 meters below the fluid passage 5 in the casing 3 of the injection well 1; the packing member 8 is disposed 10 meters above the first heat exchange passage 6 in the casing 3 of the injection well 1 . The third packing member 9 and the fourth packing member 10 are both disposed between the casing 3 of the production well 2 and the water suction pipe 4, and the third packing member 9 is disposed 10 meters above the fluid passage 5, and the fourth sealing member The spacer 10 is disposed 10 meters below the first heat exchange passage 6 between the casing 3 of the production well 2 and the water suction pipe 4.

A pressurizing device and a water injection device are installed at the wellhead of the injection well 1. A pump and a water storage device are installed at the wellhead of the production well 2.

In use, a large amount of water having a temperature of T ₀ can be continuously injected into the injection well 1 by means of a water injection device, and pressurized by a pressurizing device, and the water is heated by a dry hot rock multi-cycle heating system. Due to the barrier of the packing member 7, water flows through the fluid passage 5 into the flowing water annulus between the casing 3 in the production well 2 and the suction pipe 4; the water flows downward in the production well 2 due to the third partition packer member 9 and the fourth barrier 10, flows through the first heat exchange passages 6, heated to T _1, flows into the injector 1, to complete the first heating cycle. Next, water injection wells in a horizontal section by a vertical flow sections, the heat exchanger through the second flow passage 11 to the horizontal section of the production well 2 is heated to T _2. Water flows from the horizontal section of the production well 2 to the vertical section, and under the barrier of the fourth packing 10, flows into the water suction pipe 4 to complete the second heating cycle. At the wellhead of the production well 2, the hot water heated by the dry hot rock is taken out through the water pumping pipe 4 and the pump, and then stored in the water storage device to complete the cycle of obtaining the geothermal energy.

Example 2

Two injection wells 1 and 2, which are parallel to each other and 700 meters apart, are drilled on the surface.

The first drilling depth of the injection well 1 and the production well 2 is 300 meters, and then hydraulic fracturing is simultaneously performed at the bottom of the injection well 1 and the production well 2 to obtain the fluid passage 5.

The injection well 1 and the production well 2 are drilled vertically and drilled vertically. When drilling to 3000 meters, a second hydraulic fracturing is performed to obtain the first heat exchange passage 6.

The injection well 1 and the production well 2 Yanyuan drilling continue to drill vertically downwards, drilling to 4000 meters to change to horizontal drilling, horizontal drilling of injection well 1 and production well 2, horizontal length of 500 meters, forming L-shaped The well still keeps the injection well 1 parallel to the production well 2. Hydraulic fracturing is performed at a horizontal section of 4,000 meters deep underground to obtain a second heat exchange passage 11.

The sleeve 3 is disposed in the injection well 1, the second packing member 8 is disposed 20 meters above the first heat exchange passage 6, and the first packing member 7 is disposed at 20 meters below the fluid passage 5.

A casing 3 is provided in the production well 2, and a water suction pipe 4 is provided inside the casing 3, and a fourth packing member 10 is disposed between the casing 3 and the water suction pipe 4 at a position 20 meters below the first heat exchange passage 6. At the upper 20 meters of the fluid passage 5, a third packing member 9 is provided between the sleeve 3 and the suction pipe 4.

A pressurizing device and a water injection device are installed near the wellhead of the injection well 1. A pump and a water storage device are installed near the wellhead of the production well 2.

Example 3

Two injection wells 1 and 2, which are parallel to each other and 600 meters apart, are drilled on the surface.

The first drilling depth of the injection well 1 and the production well 2 is 150 meters, and then hydraulic fracturing is simultaneously performed at the bottom of the injection well 1 and the production well 2 to obtain the fluid passage 5.

The injection well 1 and the production well 2 Yanyuan drilling continue to drill vertically downwards, drilling to 4000 meters to change to horizontal drilling, horizontal drilling of injection well 1 and production well 2, horizontal length of 600 meters, forming L-shaped The well still keeps the injection well 1 parallel to the production well 2. Hydraulic fracturing is performed at a horizontal section of 4,000 meters deep underground to obtain a second heat exchange passage 11.

A sleeve 3 is provided in the injection well 1, a second packing member 8 is provided 20 meters above the first heat exchange passage 6, and a first packing member 7 is provided at the lower 20 meters of the fluid passage 5.

A casing 3 is provided in the production well 2, and a suction pipe 4 is provided inside the casing 3, and a fourth packing member is disposed between the casing 3 and the suction pipe 4 20 meters below the first heat exchange passage 6. 10; At the upper 20 meters of the fluid passage 5, a third packing member 9 is provided between the sleeve 3 and the suction pipe 4.

The dry hot rock multi-cycle heating system and the production method thereof of the invention can be widely applied in the fields of thermal power generation, heating equipment and the like.

The invention has been described in detail above with reference to the preferred embodiments and specific examples. It is to be understood that the above-described preferred embodiments and specific examples are intended to be illustrative and not restrictive. Various modifications or changes may be made thereto by those skilled in the art based on the present invention. For example, although the embodiment of the present invention exemplifies the present invention by performing two heat exchanges, it is obvious that the third heat exchange channel may be additionally provided for the third heat exchange as appropriate according to actual needs. Further, the heat energy utilization efficiency is further provided; in addition, although the material or configuration of some of the components in the present invention has been exemplarily described in the above description, it will be apparent to those skilled in the art that various common general knowledge or routines known in the art may be used. The technology makes various changes or reasonable choices for the materials, structures, and various details of the components that are not shown or described herein; and, for example, although specific values or ranges of values for some dimensions are given in the present invention, The numerical value or numerical range is not necessarily limited to this, but may be changed or modified within a certain range according to actual needs. These variations and modifications do not depart from the spirit and scope of the invention.

List of reference signs

1 injection well

2 production well

3 casing

4 pumping pipe

5 fluid channel

6 first heat exchange channel

7 first spacer

8 second partition

9 third partition

10 fourth partition

11 second heat exchange channel

Claims

A dry hot rock multi-cycle heating system comprising:

Injection well (1);

Production well (2);

a fluid passage (5) in fluid communication with the injection well (1) and the production well (2), respectively, at a depth relative to the ground;

a first heat exchange passage (6) formed in the underground dry hot rock and at a first depth relative to the ground, the first heat exchange passage (6) and the injection well (1) and the production, respectively Well (2) is in fluid communication;

a second heat exchange passage (11) formed in the underground dry hot rock and at a second depth relative to the ground, the second heat exchange passage (11) and the injection well (1) and the production, respectively Well (3) is in fluid communication;

a packer consisting of a packing member respectively disposed in the injection well (1) and the production well (2);

a water pump (4) disposed in the production well (2);

Wherein the water injected from the injection well (1) is allowed to pass through the fluid passage (5), the first heat exchange passage (6), and the second heat exchange passage (11) in sequence. The water suction pipe (4) is discharged from the production well (2), thereby completing a heating process including at least two heating cycles by a single water injection and at least two heat exchanges of different depths.

The second depth is greater than the first depth, and the certain depth is less than the first depth and the second depth.
The dry hot rock multi-cycle heating system according to claim 1, wherein each of said first heat exchange passage (6) and said second heat exchange passage (11) is constituted by said injection well (1) A natural fracture group or an artificial fracture group extending between the production well (2).
The dry hot rock multi-cycle heating system according to claim 2, wherein the artificial fracture group is formed by a hydraulic fracturing method or an explosion fracture method.
The dry hot rock multi-cycle heating system of claim 1 wherein said first depth is 3000 meters and said second depth is 4000 meters.
The dry hot rock multi-cycle heating system according to claim 1, wherein said fluid passage (5) is formed by an artificial fracture group formed by a hydraulic fracturing method or an explosion fracture method or Formed by a borehole, the fluid passage (5) extends between the injection well (1) and the production well (2), the depth being 100-300 meters.
The dry hot rock multi-cycle heating system according to claim 1, characterized in that the injection well (1) and the production well (2) are arranged parallel to each other with a horizontal distance between 500-700 Meter.
The dry hot rock multi-cycle heating system according to claim 1, wherein said injection well (1) and said production well (2) comprise a vertical section and a horizontal section, respectively, said first exchange a hot aisle (6) extending between a vertical section of the injection well (1) and a vertical section of the production well (2), the second heat exchange passage (11) being in the injection well The horizontal section of (1) extends between the horizontal section of the production well (2).
The dry heat rock multi-cycle heating system according to claim 7, wherein said second heat exchange passage (11) is a horizontal section formed in said injection well (1) and said production well (2) a horizontal fracture group (11) between horizontal sections, a horizontal distance from a vertical section of the injection well (1) and a vertical section of the production well (2) of at least 500 Meter.
The dry hot rock multi-cycle heating system according to claim 7, further comprising a side wall respectively disposed in a vertical section of the injection well (1) and a vertical of the production well (2) a casing (3) at a side wall of the section, the packing means comprising a seal respectively disposed in a vertical section of the injection well (1) and a vertical section of the production well (2) a partition, the fluid passage (5) being disposed between a vertical section of the injection well (1) and a vertical section of the production well (2), thereby forming such that from the injection well ( 1) The injected water returns to the vertical of the injection well (1) after passing through the fluid passage (5), the vertical section of the production well (2), and the first heat exchange passage (6) The fluid path of the section.
A dry hot rock multi-cycle heating system according to claim 9, wherein said water suction pipe (4) is disposed in a vertical section of said production well (2), said isolation means comprising a first packer (7) and a second packer (8) in a vertical section of the injection well (1), a third disposed in a vertical section of the production well (2) a packing member (9) and a fourth packing member (10), the water suction pipe (4) extending through the third packing member (9) and the fourth packing member (10), and A water flow annulus is formed between the casing (3) in the vertical section of the production well (2) and the water suction pipe (4), and the fluid passage (5) is in the first heat exchange passage ( Extending upwardly of 6), the first partition (7) and the second packing (8) separate the vertical section of the injection well (1) into an upper zone, a middle zone and a lower zone The third packing member (9) and the first Four partitions (10) divide the vertical section of the production well (2) into an upper zone, a middle zone and a lower zone, and water injected from the injection well (1) is allowed to pass through the injection well in sequence ( The upper region of the vertical section of 1), the fluid passage (5), the central region of the vertical section of the production well (2), and the first heat exchange passage (6) reach the injection well a lower region of the vertical section of (1), and then passing through the second heat exchange passage (11), the lower region of the vertical section of the production well (2) via the water suction pipe (4) Discharged from the production well (2).
A dry hot rock multi-cycle heating system according to claim 10, wherein said first packing member (7) is disposed 10-20 meters below said fluid passage (5), said second a packing member (8) is disposed 10-20 meters above the first heat exchange passage (6), and the third packing member (9) is disposed at an upper portion 10-20 of the fluid passage (5) At the meter, the fourth packing member (10) is disposed 10-20 meters below the first heat exchange passage (6).
A method for producing a dry hot rock multi-cycle heating system, comprising the following steps:

Drilling the injection well (1) and the production well (2) vertically from the ground;

Stop drilling when the injection well (1) and the production well (2) are drilled to a certain depth, respectively, and generate the same with the injection well (1) and by the horizontal drilling or manual fracturing technique respectively Production well (2) fluid communication fluid passage (5);

Continuing to drill the injection well (1) and the production well (2) to a first depth to stop drilling, respectively, by artificial fracturing technology in the underground dry hot rock and respectively to the injection well ( 1) a first heat exchange channel (6) in fluid communication with the production well (2);

Continue to drill the injection well (1) and the production well (2) to a second depth to stop vertical drilling, ending the vertical section of the injection well (1) and the production well ( 2) drilling of the vertical section, starting horizontal drilling to create a horizontal section of the injection well (1) parallel to each other and a horizontal section of the production well (2) in the underground dry hot rock ;

After drilling a certain distance horizontally, stopping drilling, and fracturing a second heat exchange channel (11) respectively in fluid communication with the injection well (1) and the production well (2) by manual fracturing technology;

Inserting a casing (3) into the injection well (1) and the production well (2), respectively;

A packing member is disposed in the casing (3) of the injection well (1) and the production well (2), respectively, and a water suction pipe is disposed in the casing (3) of the production well (2) (4) ) such that water injected from the injection well (1) is allowed to flow through the fluid passage (5), the first heat exchange passage (6) and the second heat exchange passage (11) in sequence. It is discharged from the production well (2) via the water suction pipe (4).
The method for producing a dry heat rock multi-cycle heating system according to claim 12, wherein the first heat exchange passage (6) and the second heat exchange passage (11) are respectively subjected to hydraulic fracturing Or an artificial crack group formed by a bursting method.
The method of producing a dry hot rock multi-cycle heating system according to claim 12, wherein said first depth is 3000 meters and said second depth is 4000 meters.
The method for producing a dry heat rock multi-cycle heating system according to claim 12, wherein the fluid passage (5) is an artificial fracture group formed by a hydraulic fracturing method or an explosion fracture method, the certain depth It is 100-300 meters.
The method of producing a dry hot rock multi-cycle heating system according to claim 12, characterized in that the horizontal distance between the injection well (1) and the production well (2) is 500-700 meters.
A method of producing a dry hot rock multi-cycle heating system according to claim 12, wherein said certain distance is at least 500 meters.
A method of producing a dry hot rock multi-cycle heating system according to claim 12, characterized in that said casing (3) is provided only in a vertical section of said injection well (1) and said production well ( 2) in the vertical section.
A method of producing a dry hot rock multi-cycle heating system according to claim 12, wherein the step of providing a packer comprises providing a first packer in a vertical section of the injection well (1) ( 7) and a second packing member (8) and a third packing member (9) and a fourth packing member (10) disposed in a vertical section of the production well (2), the first seal a partition (7) is disposed 10-20 meters below the fluid passage (5), and the second packing (8) is disposed 10-20 meters above the first heat exchange passage (6) Wherein the third packing member (9) is disposed 10-20 meters above the fluid passage (5), and the fourth packing member (10) is disposed at the first heat exchange passage (6) The lower part is 10-20 meters.
A method of producing a dry heat rock multi-cycle heating system according to claim 19, wherein said water suction pipe (4) passes through said third packing member (9) and said fourth packing member ( 10) Extension, a water flow annulus is formed between the casing (3) in the vertical section of the production well (2) and the suction pipe (4).