Geothermal extraction system based on deep abandoned roadway and construction method thereof

Abstract

The invention discloses a geothermal extraction system based on a deep abandoned roadway and a construction method of the geothermal extraction system. The geothermal extraction system based on the deep abandoned roadway comprises a plugging material, a high-temperature water pipeline, a heat pump unit, a low-temperature water pipeline and an inclined drill hole, the heat pump unit is located on the ground or in a shallow underground space, the construction area of the heat pump unit is located above the deep abandoned roadway, and a shallow underground water layer is located above the deep abandoned roadway; the construction method of the geothermal extraction system based on the deep abandoned roadway specifically comprises the steps of drilling an inclined drill hole, blocking the deep abandoned roadway and laying a pipeline. According to the scheme, shallow groundwater and deep surrounding rock are thermally combined, the shallow groundwater is used as a medium, and heat exchange is completed between a deep abandoned roadway and the surrounding rock; compared with a traditional geothermal well, according to the scheme, an original deep abandoned roadway is utilized, the working procedures of deep well drilling, hole fixing, drilling and pipe lowering and the like do not need to be conducted, and the construction cost of the deep geothermal well is reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of geothermal energy extraction, and in particular provides a geothermal energy extraction system based on a deep abandoned tunnel and a construction method thereof. Background Art

[0002] With the development of excavation technology, mining operations have gradually tended to dig deep mines. The deeper the mine, the higher the temperature of the surrounding rock.

[0003] At present, the common method for dealing with deep abandoned tunnels is backfilling and sealing. Since deep tunnels are located deep underground and the temperature of the surrounding rocks is relatively high, they have the potential to become high-quality thermal energy resources.

[0004] Conventional geothermal heat extraction methods require drilling deep wells and installing equipment such as U-shaped pipes or concentric pipes. The equipment cost, construction cost and subsequent maintenance cost are relatively high. Summary of the invention

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is: a geothermal extraction system based on a deep abandoned tunnel, comprising a plugging material, a high-temperature water pipeline, a heat pump unit, a low-temperature water pipeline and an inclined borehole, the heat pump unit is located above the ground or in a shallow underground space, the construction area of ​​the heat pump unit is located above the deep abandoned tunnel, and there is a shallow groundwater layer above the deep abandoned tunnel;

[0006] Drill an inclined borehole between the shallow groundwater layer and the deep abandoned tunnel, the inclined borehole penetrates the shallow rock mass and the deep rock mass, connects the shallow groundwater layer and the deep abandoned tunnel, and introduces groundwater from the shallow groundwater layer into the deep abandoned tunnel;

[0007] The underground port of the high-temperature water pipeline extends into the closed space, and the above-ground port of the high-temperature water pipeline is connected to the circulation input side of the heat pump unit;

[0008] The underground port of the low-temperature water pipeline extends into the shallow groundwater layer, and the above-ground port of the low-temperature water pipeline is connected to the circulation output side of the heat pump unit.

[0009] A construction method of a geothermal extraction system based on deep abandoned tunnels, the specific process is as follows:

[0010] Step 1: Drilling an inclined borehole;

[0011] Deploy the drilling rig into the deep abandoned tunnel and drill from bottom to top;

[0012] The inclination angle of the inclined drilling is α, the number of holes is n, and the hole diameter is d;

[0013] The angle of α is set according to the depth of the shallow groundwater layer and the horizontal distance between the shallow groundwater layer and the deep abandoned tunnel;

[0014] In order to ensure the balance between water intake and water inflow, according to the formula n = K (Q 取 / q 测 ) Calculate the number of openings;

[0015] in:

[0016] n is the number of holes required;

[0017] Q 取 The water intake required for the heat pump unit;

[0018] K is the loss coefficient, which is 1.1 to 1.2;

[0019] q 测 is the single hole flow rate of the test hole.

[0020] Step 2: Block the deep abandoned tunnels;

[0021] Step 3: Laying pipelines;

[0022] Furthermore, in step one, before the drilling construction officially begins, a test hole is first drilled to measure the flow rate, and then a drilling plan for the formal drilling is formulated based on the drilling parameters of the test hole, and continuous drilling is implemented.

[0023] Furthermore, in step one, during the drilling construction process, a borehole back pressure device needs to be installed in the inclined borehole.

[0024] Furthermore, when the upper part of the abandoned tunnel is a loose rock layer, the final hole diameter d of the inclined drilling should be less than 94 mm.

[0025] Furthermore, in step 2, when the deep abandoned tunnel is blocked, high thermal conductivity cement is used to spray the surrounding areas of the abandoned tunnel.

[0026] The beneficial effects of using the present invention are:

[0027] This scheme combines shallow groundwater with deep surrounding rock heat, using shallow groundwater as a medium to complete heat exchange with the surrounding rock in deep abandoned tunnels;

[0028] Compared with traditional geothermal wells, this solution utilizes the original deep abandoned tunnels, and does not require deep well drilling, hole fixing, and drilling pipe laying processes, thus reducing the construction cost of deep geothermal wells.

[0029] At the same time, the construction materials and construction costs required for backfilling deep abandoned tunnels are reduced;

[0030] Shallow groundwater is directly used as the heat exchange medium. The circulation process does not involve the relevant processes such as replenishing hot water, and the water transportation cost is also saved;

[0031] Compared with traditional geothermal wells, deep abandoned tunnels have larger space and larger heat exchange area;

[0032] The depth of deep abandoned tunnels is generally below the shallow groundwater layer, and the existence of groundwater in the stratum is a common geographical condition. Therefore, this plan is not a targeted plan for special geographical environments and has strong promotion value. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a structural schematic diagram of the present invention;

[0034] The reference numerals include: 1. ground surface; 2. shallow groundwater layer; 3. shallow rock mass; 4. deep rock mass; 5. deep abandoned tunnel; 6. sealing material; 7. sealing plate; 8. high-temperature water pipeline; 9. heat pump unit; 10. low-temperature water pipeline; 11. inclined borehole. DETAILED DESCRIPTION

[0035] The present invention is described in detail below with reference to the accompanying drawings.

[0036] Embodiment 1

[0037] Reference Figure 1 , a geothermal extraction system based on a deep abandoned tunnel, comprising a plugging material 6, a high-temperature water pipeline 8, a heat pump unit 9, a low-temperature water pipeline 10 and an inclined borehole 11, the heat pump unit 9 is located above the ground or in a shallow underground space, the construction area of ​​the heat pump unit 9 is located above the deep abandoned tunnel 5, and there is a shallow groundwater layer 2 above the deep abandoned tunnel 5;

[0038] The deep abandoned tunnel 5 is located in the deep rock mass 4;

[0039] An inclined borehole 11 is drilled between the shallow groundwater layer 2 and the deep abandoned tunnel 5. The inclined borehole 11 penetrates the shallow rock mass 3 and the deep rock mass 4, connects the shallow groundwater layer 2 and the deep abandoned tunnel 5, and introduces groundwater from the shallow groundwater layer 2 into the deep abandoned tunnel 5.

[0040] The underground port of the high-temperature water pipeline 8 extends into the closed space, and the above-ground port of the high-temperature water pipeline 8 is connected to the circulation input side of the heat pump unit 9;

[0041] The underground port of the low-temperature water pipeline 10 extends into the shallow underground water layer 2 , and the above-ground port of the low-temperature water pipeline 10 is connected to the circulation output side of the heat pump unit 9 .

[0042] Preferably, a valve is provided on the high-temperature water pipeline 8 to control the heat exchange flow and heat exchange time.

[0043] Cold groundwater in the shallow groundwater layer 2 flows into the deep abandoned tunnel 5, absorbs heat from the deep rock mass 4 inside and around the deep abandoned tunnel 5 and becomes hot water. The hot water circulates to the heat pump unit 9 through the high-temperature water pipeline 8. The heat pump unit 9 exchanges and outputs the heat in the hot water. The cooled water flows back to the shallow groundwater layer 2 through the low-temperature water pipeline 10, forming a closed heat exchange cycle.

[0044] Embodiment 2

[0045] A construction method of a geothermal extraction system based on deep abandoned tunnels, the specific process is as follows:

[0046] Step 1: Drilling an inclined borehole 11.

[0047] Specifically, the drilling rig is deployed into the deep abandoned tunnel 5 and drilling is performed from bottom to top;

[0048] First, a test hole is drilled (using known technical means, based on hydrogeological data and previous geophysical exploration results, the direction, length and angle of the test hole can be preliminarily determined) to measure the flow rate until the shallow groundwater layer 2 is reached;

[0049] Then, a drilling plan for formal drilling is formulated according to the drilling parameters of the test hole, and continuous drilling is carried out to complete the construction of multiple inclined boreholes 11.

[0050] The inclined borehole 11 has an inclination angle of α, a number of holes of n, and a hole diameter of d;

[0051] The angle α is set according to the depth of the shallow groundwater layer 2 and the horizontal distance between the shallow groundwater layer 2 and the deep abandoned tunnel 5;

[0052] In order to ensure the balance between water intake and water inflow, according to the formula n = K (Q 取 / q 测 ) Calculate the number of openings;

[0053] in:

[0054] n is the number of holes required;

[0055] Q 取 The water intake required by the heat pump unit 9;

[0056] K is the loss coefficient (taking into account the leakage of sealed space and drilling holes, which will cause water loss), and is set to 1.1-1.2;

[0057] q 测 is the single hole flow rate of the test hole.

[0058] Preferably, during the drilling construction process, a borehole back pressure device needs to be provided in the inclined borehole 11 to prevent water from gushing out.

[0059] Preferably, when the shallow groundwater layer 2 is deeper, the inclination angle α of the inclined borehole 11 is usually between 45 and 60 degrees to prevent excessive water pressure or excessively fast water flow from eroding the inclined borehole 11;

[0060] When the shallow groundwater layer 2 is relatively shallow, the inclination angle α of the inclined borehole 11 may be a 90-degree vertical hole.

[0061] Preferably, when the upper part of the abandoned tunnel is a loose rock layer, a drilling method of opening a large number of small holes is adopted. In order to avoid hole collapse and tunnel collapse, the final hole diameter d of the inclined drilling hole 11 should be less than 94 mm;

[0062] When the upper part of the abandoned tunnel is hard rock such as slightly weathered or unweathered granite, a drilling method of opening a small number of large holes is adopted, and the specific hole diameter d is set according to the rock hardness measurement data.

[0063] Step 2: seal the deep abandoned tunnel 5.

[0064] Specifically, the two ends of the deep abandoned tunnel 5 are blocked with the blocking material 6 to form a closed space.

[0065] Preferably, when the deep abandoned tunnel 5 is blocked, high thermal conductivity cement is used to spray the surroundings of the abandoned tunnel to reduce the permeability of the closed space and ensure that the groundwater can stay in the closed space for heat exchange;

[0066] In the plugging construction process, the deep abandoned tunnel 5 is firstly cut off with the plugging plate 7, and then the plugging material 6 is poured in.

[0067] Step 3: Laying pipelines.

[0068] Specifically, the high-temperature water pipeline 8 is laid along the abandoned lane until it reaches the ground;

[0069] A hole is drilled downwards from the ground surface 1 around the heat pump unit 9, the hole extending into the shallow groundwater layer 2, and then a low-temperature water pipeline 10 is laid along the hole.

[0070] Preferably, the drilling construction of the inclined borehole 11 adopts a crawler-type special drilling rig for water exploration and drainage.

[0071] The above contents are only preferred embodiments of the present invention. For ordinary technicians in this field, many changes can be made in the specific implementation methods and application scopes based on the ideas of the present invention. As long as these changes do not deviate from the concept of the present invention, they all belong to the protection scope of the present invention.

Claims

1. A geothermal extraction system based on deep abandoned tunnels, characterized by: Including plugging materials, high-temperature water pipelines, heat pump units, low-temperature water pipelines and inclined boreholes, the heat pump units are located above the ground or in shallow underground space, the construction area of ​​the heat pump units is located above the deep abandoned tunnel, and there is a shallow groundwater layer above the deep abandoned tunnel; Drill an inclined borehole between the shallow groundwater layer and the deep abandoned tunnel, the inclined borehole penetrates the shallow rock mass and the deep rock mass, connects the shallow groundwater layer and the deep abandoned tunnel, and introduces groundwater from the shallow groundwater layer into the deep abandoned tunnel; The underground port of the high-temperature water pipeline extends into the closed space, and the above-ground port of the high-temperature water pipeline is connected to the circulation input side of the heat pump unit; The underground port of the low-temperature water pipeline extends into the shallow groundwater layer, and the above-ground port of the low-temperature water pipeline is connected to the circulation output side of the heat pump unit.

2. A construction method of a geothermal extraction system based on deep abandoned tunnels, the specific process is as follows: Step 1: Drilling an inclined borehole; Deploy the drilling rig into the deep abandoned tunnel and drill from bottom to top; The inclination angle of the inclined drilling is α, the number of holes is n, and the hole diameter is d; The angle of α is set according to the depth of the shallow groundwater layer and the horizontal distance between the shallow groundwater layer and the deep abandoned tunnel; In order to ensure the balance between water intake and water inflow, according to the formula n = K (Q 取 / q 测 ) Calculate the number of openings; in: n is the number of holes required to be drilled; Q 取 The water intake required for the heat pump unit; K is the loss coefficient, which is 1.1 to 1.2; q 测 is the single hole flow rate of the test hole; Step 2: Block the deep abandoned tunnels; Step 3: Laying pipelines.

3. A construction method for a geothermal extraction system based on a deep abandoned tunnel according to claim 2, characterized in that: In step one, before the drilling construction officially begins, a test hole is drilled to measure the flow rate, and then a drilling plan for the formal drilling is formulated based on the drilling parameters of the test hole, and continuous drilling is implemented.

4. A construction method for a geothermal extraction system based on a deep abandoned tunnel according to claim 2, characterized in that: In step one, during the drilling construction process, a borehole back pressure device needs to be installed in the inclined borehole.

5. A construction method for a geothermal extraction system based on a deep abandoned tunnel according to claim 2, characterized in that: When the upper part of the abandoned tunnel is loose rock, the final hole diameter d of the inclined drilling should be less than 94mm.

6. A construction method for a geothermal extraction system based on a deep abandoned tunnel according to claim 2, characterized in that: In step 2, when sealing the deep abandoned tunnel, high thermal conductivity cement is used to spray the surrounding areas of the abandoned tunnel.

Images