A geothermal mining system

Abstract

The embodiment of the present application discloses a geothermal extraction system, including an undisturbed well, an extraction well and a reinjection well, wherein the reinjection well is located upstream of the undisturbed well, and the extraction well is located downstream of the undisturbed well. This solution combines the two geothermal extraction technologies of water extraction and reinjection and heat exchange in undisturbed wells, but it is not a simple superposition of the two technologies. Specifically, on the basis of utilizing geothermal energy, the extraction well and the reinjection well can also increase the hydraulic gradient of the heat storage flow field between the upstream and downstream of the undisturbed well to accelerate the groundwater flow rate and promote the recovery of the geothermal field. The groundwater flow rate of the heat storage flow field is accelerated, and the heat exchange efficiency of the undisturbed heat exchange system shows an increasing trend, which can effectively alleviate the phenomenon of cold and heat accumulation in the undisturbed heat exchange system.

Description

Technical Field

[0001] The present application relates to the field of geothermal mining technology, and in particular to a geothermal mining system. Background Art

[0002] Today, the world's energy crisis and environmental problems are becoming increasingly severe. The development of new alternative energy sources with large reserves and environmental friendliness has gradually attracted the attention of scientists from various countries. Geothermal resources have become a new type of clean energy that countries around the world focus on researching and developing due to their extremely high cleanliness, operational stability and wide spatial distribution.

[0003] Medium-deep hydrothermal geothermal resources are widely distributed in my country, with huge resources. The main development and utilization methods are water extraction and recharge and non-interference underground heat exchange. Water extraction and recharge face the problem of recharge difficulties during the mining process, and it is often impossible to achieve 100% recharge. The discharge of geothermal water that has not been recharged causes a waste of groundwater resources and also causes environmental geological problems; non-interference underground heat exchange is limited by the thermal properties of the heat storage medium and the heat exchange area between the heat pipe and the medium. The heat exchange capacity is generally less than 50kW in actual applications, and as the use time increases, it will cause cold accumulation around the well, and the heat exchange capacity will continue to decline.

[0004] Therefore, how to solve the problem of cold accumulation around undisturbed wells has become a technical problem that needs to be solved urgently by those skilled in the art. Summary of the invention

[0005] The present application proposes a geothermal production system to solve the problem of cold accumulation around wells without interference with the wells.

[0006] In order to achieve the above-mentioned purpose, the present application provides a geothermal production system, including a non-interference well, a production well and a reinjection well.

[0007] The reinjection well is located upstream of the undisturbed well, and the production well is located downstream of the undisturbed well. The reinjection well and the production well are used to increase the hydraulic gradient of the heat storage flow field between the upstream and downstream of the undisturbed well to accelerate the flow rate of groundwater.

[0008] Preferably, in the above geothermal production system, the distance between the production well and the non-interference well is smaller than the distance between the reinjection well and the non-interference well.

[0009] Preferably, in the above geothermal production system, the distance between the production well and the non-interference well is greater than half of the reservoir influence radius and less than the reservoir influence radius.

[0010] Preferably, in the above geothermal production system, the distance between the reinjection well and the non-interference well is greater than the reservoir influence radius and less than three times the reservoir influence radius.

[0011] Preferably, in the above geothermal production system, there is at least one production well and at least one reinjection well, and the production well corresponds to the reinjection well one by one.

[0012] Preferably, in the above-mentioned geothermal production system, the non-interference wells are arranged in a rectangular shape.

[0013] Preferably, in the above geothermal production system, the distance between two adjacent non-interference wells is 3-10 m.

[0014] The embodiment of the present application provided by the embodiment of the present application discloses a geothermal extraction system, including an undisturbed well, an extraction well and a reinjection well, wherein the reinjection well is located upstream of the undisturbed well, and the extraction well is located downstream of the undisturbed well. This scheme combines the two geothermal extraction technologies of water extraction and reinjection and undisturbed well heat exchange, but it is not a simple superposition of the two technologies. Specifically, on the basis of utilizing geothermal energy, the extraction well and the reinjection well can also increase the hydraulic gradient of the heat storage flow field between the upstream and downstream of the undisturbed well to accelerate the groundwater flow rate and promote the recovery of the geothermal field. The groundwater flow rate of the heat storage flow field is accelerated, and the heat exchange efficiency of the undisturbed heat exchange system shows an increasing trend, which can effectively alleviate the phenomenon of cold and heat accumulation in the undisturbed heat exchange system. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. Obviously, the drawings described below are only some examples or embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without creative work, and the present application can also be applied to other similar scenarios based on the provided drawings. Unless it is obvious from the language environment or otherwise explained, the same reference numerals in the figures represent the same structure or operation.

[0016] Figure 1 is a front view of the geothermal mining system of the present application;

[0017] Figure 2 It is a top view of the geothermal extraction system of the present application.

[0018] in:

[0019] 1. Non-interference well, 2. Production well, 3. Recharge well. DETAILED DESCRIPTION

[0020] The present application will be further described in detail below in conjunction with the accompanying drawings and embodiments. It will be understood that the specific embodiments described herein are only used to explain the related application, rather than to limit the application. The described embodiments are only a part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present application.

[0021] See also Figure 1 and Figure 2 .

[0022] Some embodiments of the present application disclose a geothermal production system, including an undisturbed well 1, a production well 2 and a reinjection well 3, wherein the reinjection well 3 is located upstream of the undisturbed well 1 and the production well 2 is located downstream of the undisturbed well 1.

[0023] The geothermal mining system disclosed in this scheme combines two geothermal mining technologies, water extraction and reinjection and non-interference well heat exchange, but it is not a simple superposition of the two technologies. Specifically, on the basis of utilizing geothermal energy, the mining well 2 and reinjection well 3 can also increase the hydraulic gradient of the heat storage flow field between the upstream and downstream of the non-interference well 1, accelerate the groundwater flow rate, and promote the recovery of the geothermal field; the groundwater flow rate of the heat storage flow field is accelerated, and the heat exchange efficiency of the non-interference heat exchange system is increasing, which can effectively alleviate the phenomenon of cold and heat accumulation in the non-interference heat exchange system.

[0024] At the same time, water injection and reinjection heat exchange only requires a small amount of extraction and reinjection to achieve the effect of increasing the hydraulic gradient of the heat storage flow field between the upstream and downstream of the undisturbed well 1, which greatly reduces the difficulty of reinjection of water injection and reinjection to a certain extent. After all, the larger the reinjection amount, the more difficult it is to achieve 100% reinjection. Specifically, it is only necessary to determine the extraction amount according to the actual reinjection amount of the reservoir to solve the reinjection problem of water injection and reinjection, and at the same time achieve the purpose of increasing the hydraulic gradient of the heat storage flow field between the upstream and downstream of the undisturbed well 1, thereby improving the efficiency of geothermal utilization.

[0025] Among them, water recharge is to pump underground hot water to the ground, extract the heat energy therein through a heat exchanger, and then recharge it into the underground. The extraction well 2 and the recharge well 3 are connected to the water source heat pump unit through pipelines, and the water source heat pump unit is connected to the domestic water supply equipment through pipelines.

[0026] Mid-deep undisturbed downhole heat exchange utilizes the natural geothermal temperature of mid-deep formations to preheat the circulating medium, circulates the internal fluid of a single well through coaxial casing in a deep well, and exchanges heat with the formation based on heat conduction. It is a geothermal heating method that only takes heat but not water.

[0027] The water injection and reinjection of the geothermal extraction system disclosed in the present application and the undisturbed well 1 can both transport geothermal heat to the outside. The water injection and reinjection can not only meet the geothermal utilization but also increase the hydraulic gradient upstream and downstream of the undisturbed well 1, increase the water flow rate, and accelerate the geothermal recovery of the well field of the undisturbed well 1, thereby improving the heat exchange efficiency of the undisturbed well 1.

[0028] First, the thermal reservoir characteristics of the heat storage flow field are investigated and studied to obtain the depth, thickness, pumping layer, natural groundwater flow direction and reservoir influence radius of the thermal reservoir; then, a reinjection well 3 is arranged upstream of the natural flow field, and a production well 2 is arranged downstream, and the number of production wells 2 and reinjection wells 3 is increased or decreased according to the well field range of the non-interference well 1. Specifically, the number of production wells 2 and reinjection wells 3 is at least one, and the production wells 2 and reinjection wells 3 correspond one to one.

[0029] In the embodiment where there are multiple production wells 2 and reinjection wells 3, the multiple production wells 2 can be distributed equidistantly or unequally, and the multiple reinjection wells 3 can be distributed equidistantly or unequally, and the specific distribution method is determined according to the characteristics of the thermal reservoir.

[0030] In this scheme, the distance between the production well 2 and the non-interference well 1 is smaller than the distance between the recharge well 3 and the non-interference well 1. The temperature of the water in the production well 2 is higher than that in the recharge well 3, so as to reduce the influence of the low-temperature return water of the recharge well 3 on the heat exchange of the non-interference well, and at the same time reduce the influence of the cold and heat accumulation of the non-interference well 1 on the temperature of the production well 2.

[0031] In this scheme, the distance between the mining well 2 and the undisturbed well 1 is greater than half of the reservoir influence radius and less than the reservoir influence radius. If the distance between the mining well 2 and the undisturbed well 1 is too small, cold accumulation will occur in the undisturbed well 1 field, causing the outlet water temperature of the mining well 2 to decrease. If the distance is too large, the hydraulic gradient will be reduced, which is not conducive to accelerating the groundwater flow rate, and the effect of alleviating the cold accumulation around the undisturbed well 1 is not significant.

[0032] In this scheme, the distance between the recharge well 3 and the undisturbed well 1 is greater than the reservoir influence radius and less than three times the reservoir influence radius. If the distance between the production well 2 and the undisturbed well 1 is too small, the low-temperature return water of the recharge well 3 will reduce the heat exchange efficiency of the undisturbed well 1. If the distance between the production well 2 and the undisturbed well 1 is too large, the hydraulic gradient will be reduced, which is not conducive to accelerating the groundwater flow rate, and the effect of alleviating the cold accumulation around the undisturbed well 1 is not significant.

[0033] The reservoir influence radius is the distance from the center of the wellbore to the boundary of the influence range.

[0034] like Figure 2As shown, the non-interference wells 1 are arranged in a rectangular shape. The spacing between the non-interference wells 1 is generally 3-10m, the number of the non-interference wells 1 is increased or decreased as needed, and the arrangement is adjusted according to the thermal reservoir conditions and is not limited to a rectangle.

[0035] This solution achieves artificial enhanced geothermal exploitation by setting a reinjection well 3 upstream of the undisturbed well 1 and a production well 2 downstream, thereby alleviating the continuous decrease in heat exchange and improving the geothermal utilization efficiency of the heat reservoir.

[0036] The above description is only a preferred embodiment of the present application and an explanation of the technical principles used, and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. The scope of application involved in the present application is not limited to the technical solution formed by a specific combination of the above-mentioned technical features, but should also cover other technical solutions formed by any combination of the above-mentioned technical features or their equivalent features without departing from the above-mentioned application concept. For example, the above-mentioned features are replaced with the technical features with similar functions disclosed in this application (but not limited to) to form a technical solution.

Claims

1. A geothermal mining system, characterized in that: It includes undisturbed wells (1), production wells (2) and reinjection wells (3). The reinjection well (3) is located upstream of the undisturbed well (1), and the production well (2) is located downstream of the undisturbed well (1). The reinjection well (3) and the production well (2) are used to increase the hydraulic gradient of the heat storage flow field between the upstream and downstream of the undisturbed well (1) to accelerate the flow rate of groundwater. The distance between the production well (2) and the non-interference well (1) is greater than half of the reservoir influence radius and less than the reservoir influence radius.

2. The geothermal mining system according to claim 1, characterized in that: The distance between the production well (2) and the non-interference well (1) is smaller than the distance between the reinjection well (3) and the non-interference well (1).

3. The geothermal mining system according to claim 1 or 2, characterized in that: The distance between the reinjection well (3) and the non-interference well (1) is greater than the reservoir influence radius and less than three times the reservoir influence radius.

4. The geothermal mining system according to claim 1, characterized in that: There is at least one extraction well (2) and at least one reinjection well (3), and the extraction well (2) corresponds to the reinjection well (3) in one-to-one correspondence.

5. The geothermal mining system according to claim 1, characterized in that: The non-interference wells (1) are arranged in a rectangular shape.

6. The geothermal mining system according to claim 1, characterized in that: The distance between two adjacent undisturbed wells (1) is 3-10 m.

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