Reasonable mining and irrigation well spacing calculation method and system for thermal breakthrough constraint of terrestrial heat on well mining and irrigation system

Abstract

The invention discloses a reasonable mining and irrigation well spacing calculation method and system for thermal breakthrough constraint of terrestrial heat on a well mining and irrigation system, and relates to the technical field of data processing. On the basis of the law of conservation of energy, a mining and irrigation well spacing calculation model is built, and the mining and irrigation well spacing calculation model is obtained after derivation of a reasonable mining and irrigation well spacing calculation formula of the well mining and irrigation system through existing terrestrial heat; and the thermal reservoir parameters are input into the extraction and irrigation well spacing calculation model to be processed, and the extraction and irrigation well spacing is obtained. According to the method, more accurate prediction of the thermal breakthrough time of the mining well is realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of data processing, and particularly relates to a method and system for calculating a reasonable interwell distance of a geothermal interwell production and injection system under the constraint of thermal breakthrough. BACKGROUND

[0002] Geothermal resources are the geothermal energy inside the earth that can be economically utilized by human beings, and are a kind of renewable clean energy with large reserves, wide distribution and green low carbon. In recent years, renewable clean energy is becoming increasingly scarce, and environmental problems are becoming increasingly serious, so geothermal energy has gradually attracted people's attention, and a round of geothermal development has been launched. However, large-scale exploitation of deep geothermal water will cause the heat reservoir pressure to drop, reduce the utilization rate of geothermal resources, and direct discharge of tail water will also cause serious waste of water resources and thermal pollution and water chemical pollution of the surrounding environment. Geothermal reinjection plays an important role in improving the utilization rate of geothermal resources, reducing tail water discharge and maintaining heat reservoir pressure, and realizing the sustainable utilization of geothermal resources.

[0003] Because the temperature of the reinjected geothermal tail water is much lower than the temperature of the reservoir, reinjection will inevitably cause the temperature of the reservoir to decrease. When the cold front of the reinjected tail water moves to the production well, it will cause thermal breakthrough of the production well. As the water temperature of the production well continues to decrease, the utilization rate of geothermal resources also rapidly decreases until the production well loses its value.

[0004] Therefore, it is of great significance to study the temperature change of the production well caused by geothermal tail water reinjection. The derivation of the existing theoretical formula for calculating the reasonable interwell distance of a geothermal interwell production and injection system under the constraint of thermal breakthrough is based on ideal assumptions, and only considers the forced convection of cold water into the heat reservoir after reinjection, without considering the influence of heat exchange between cold and hot water in the heat reservoir. SUMMARY

[0005] The present application aims to provide a method and system for calculating a reasonable interwell distance of a geothermal interwell production and injection system under the constraint of thermal breakthrough, so as to provide a scientific basis for the optimal design of a geothermal interwell production and injection system, and achieve the goal of prolonging the service life of the geothermal system, improving the efficiency of geothermal resource exploitation, and ensuring the sustainable development of medium and deep geothermal resources.

[0006] In one aspect, to achieve the above-mentioned purpose, the present application provides a method for calculating a reasonable interwell distance of a geothermal interwell production and injection system under the constraint of thermal breakthrough, comprising: obtaining the heat reservoir parameters of the region to be measured; constructing an interwell distance calculation model based on the law of conservation of energy, wherein the interwell distance calculation model is obtained by deducing the existing formula for calculating the reasonable interwell distance of a geothermal interwell production and injection system; inputting the heat reservoir parameters into the interwell distance calculation model for processing to obtain the interwell distance.

[0007] Preferably, the thermal reservoir parameters include a thermal reservoir effective thickness, a thermal reservoir density, a recharged water specific heat capacity, a recharged water volume and a thermal reservoir specific heat capacity; wherein the thermal reservoir effective thickness is obtained from a geothermal well completion report, and the thermal reservoir density, the recharged water specific heat capacity, the recharged water volume and the thermal reservoir specific heat capacity are all obtained after test.

[0008] Preferably, the reasonable recharging well spacing of the geothermal well recharging system is derived by a formula, including: The recharging well is regarded as a low-temperature source point, that is, the recharged low-temperature water forms a radial temperature gradient in the thermal reservoir. The recharging well spacing is divided into several small equal parts by a differential model, and the heat loss of the ring body at a distance d from the recharging well is calculated. x x The total heat loss of the thermal reservoir at the heat breakthrough is calculated by integration. According to the principle that the heat extracted by the surface heat exchange system is equal to the total heat loss of the thermal reservoir, the recharging well spacing calculation model is derived.

[0009] Preferably, the heat loss of the ring body at a distance d from the recharging well is calculated as: x In the formula, E lost-dx Q is the heat loss of the ring body at a distance d from the recharging well, x H is the thermal reservoir effective thickness, H T0 is the water temperature, T T1 is the recharged water temperature, T D0 is the reasonable recharging well spacing of the geothermal well recharging system, r ρ is the thermal reservoir density, p C is the thermal reservoir specific heat capacity. C

[0010] Preferably, the total heat loss of the thermal reservoir at the heat breakthrough includes: When d > D0, the heat breakthrough occurs, and the total heat loss of the thermal reservoir is: In the formula, E lost Q is the total heat loss of the thermal reservoir.

[0011] Preferably, the heat extracted by the surface heat exchange system is: In the formula, E used Q is the heat extracted by the surface heat exchange system, Q V is the recharged water volume, t ​​​​​​​a design operation life of the well injection and production system, p w a recharge water density, C w a specific heat capacity of the recharge water.

[0012] Preferably, the well injection and production system distance calculation model is: ; In the formula, r 0 is a reasonable well injection and production system distance of the geothermal well injection and production system, p w a recharge water density, C w a specific heat capacity of the recharge water, Q a recharge water amount, t a design operation life of the well injection and production system, H an effective thickness of the heat reservoir, represents a heat capacity per unit volume of the heat reservoir.

[0013] Preferably, the heat capacity per unit volume of the heat reservoir is: ; In the formula, is a porosity of the heat reservoir, p r is a density of the heat reservoir rock, C r is a specific heat capacity of the heat reservoir rock.

[0014] Preferably, conditions applicable to the well injection and production system distance calculation model include: the heat reservoir is homogeneous and isotropic, the roof depth and thickness are the same, the permeability and porosity are stable; the layer, well structure and well depth of the production well and the injection well are the same, and the water filter pipes all pass through the heat reservoir; the recharge water temperature is constant, and the initial heat reservoir temperature is constant.

[0015] In another aspect, to achieve the above-mentioned purpose, the present application also provides a reasonable well injection and production system distance calculation system for a geothermal well injection and production system heat breakthrough constraint, comprising: a parameter acquisition module: used for acquiring heat reservoir parameters of a region to be measured; a model construction module: used for constructing a well injection and production system distance calculation model based on the law of conservation of energy, wherein the well injection and production system distance calculation model is obtained by deducing an existing reasonable well injection and production system distance calculation formula of the geothermal well injection and production system; a result output module: used for inputting the heat reservoir parameters into the well injection and production system distance calculation model for processing to obtain a well injection and production system distance.

[0016] Compared with the prior art, the present application has the following advantages and technical effects: The present application provides a calculation model of well spacing, which, compared with the prior art, considers the heat exchange between cold water and hot water after the cold water is injected into the hot reservoir, improves the prediction accuracy of the thermal breakthrough time of the production well, and realizes more accurate prediction of the thermal breakthrough time of the production well. BRIEF DESCRIPTION OF DRAWINGS

[0017] The accompanying drawings, which form a part of the present application, are intended to provide further understanding of the present application, and the illustrative embodiments of the present application and their description serve the purpose of explaining the present application. The accompanying drawings should not be construed as an inappropriate limitation on the present application. In the drawings: Figure 1 Flow chart of the reasonable well spacing calculation method of the geothermal pair well production and injection system thermal breakthrough constraint of the embodiment of the present application; Figure 2 Schematic diagram of the geothermal pair well production and injection engineering in the embodiment of the present application; Figure 3 Schematic diagram of the recharging low-temperature water cold front migration and geothermal field evolution in the embodiment of the present application; Figure 4 Schematic diagram of the recharging well as a source point in the embodiment of the present application x d of the radius x Plan position map. DETAILED DESCRIPTION

[0018] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0019] It should be noted that the steps shown in the flow chart of the accompanying drawings can be executed in a computer system such as a group of computer executable instructions, and although the logical order is shown in the flow chart, in some cases, the steps shown or described herein can be executed in an order different from that shown herein.

[0020] The present embodiment proposes a reasonable well spacing calculation method of the geothermal pair well production and injection system thermal breakthrough constraint, as shown in Figure 1 , including: obtaining the thermal reservoir parameters of the region to be measured; constructing a well spacing calculation model based on the law of conservation of energy, wherein the well spacing calculation model is obtained by deducing the existing reasonable well spacing calculation formula of the geothermal pair well production and injection system; inputting the thermal reservoir parameters into the well spacing calculation model for processing to obtain the well spacing.

[0021] Specifically, the embodiment is based on the principle of energy conservation (the first law of thermodynamics), and a calculation model of the distance between the production well and the injection well is constructed based on the heat exchange between hot and cold water in the heat reservoir, so that the occurrence time of the hot breakthrough of the production well is accurately predicted, thereby providing a scientific basis for the optimized design of the geothermal well pair system, and achieving the goals of prolonging the service life of the geothermal system, improving the exploitation efficiency of geothermal resources, and ensuring the sustainable development of medium-deep geothermal resources.

[0022] Further, the heat reservoir parameters include a heat reservoir effective thickness, a heat reservoir density, a specific heat capacity of the recharge water, a recharge water volume, and a specific heat capacity of the heat reservoir; the heat reservoir effective thickness is obtained from a geothermal well completion report, and the heat reservoir density, the specific heat capacity of the recharge water, the recharge water volume, and the specific heat capacity of the heat reservoir are obtained after test.

[0023] Further, the reasonable distance between the production well and the injection well of the existing geothermal well pair system is derived, including: The recharge well is regarded as a low-temperature source point, that is, the recharge of low-temperature water forms a radial temperature gradient in the heat reservoir; The distance between the production well and the injection well is divided into several small equal parts through a differential model, and the heat loss of the recharge well x d x The width of the annular body, and the total heat loss of the heat reservoir at the time of the hot breakthrough is calculated by integration; According to the principle that the heat extracted by the surface heat exchange system is equal to the total heat loss of the heat reservoir, the calculation model of the distance between the production well and the injection well is derived.

[0024] Specifically, based on the reasonable distance between the production well and the injection well of the existing geothermal well pair system, that is, the calculation formula of the hot breakthrough time of the production well of the geothermal well pair system proposed by Bodvarsson in 1972, the main applicable conditions and the specific formula are as follows: The heat reservoir is horizontal and equal in thickness, the overburden and the underlying rock are impermeable, the initial temperature of the aquifer and the overburden and underlying rock temperature are the same, and the overburden and the underlying rock temperature of the heat reservoir is constant; The production rate, recharge flow rate, and recharge water temperature are stable, the horizontal and vertical heat conduction of the heat reservoir is ignored, the water and rock in the heat reservoir instantaneously reach thermal equilibrium, and the temperature of the rock and water is the same; It is assumed that the heat transfer of heat conduction can be ignored relative to convective heat transfer, and after ignoring the heat conduction term, the cold front will move radially around the recharge well, and the calculation formula of the hot breakthrough time of the production well of the geothermal well pair system is obtained: ; In the formula, r 0 is the reasonable distance between the production well and the injection well of the geothermal well pair system; Q is the recharge water volume; tThe design operation life of the well-pumping system; H The effective thickness of the thermal reservoir (i.e. the aquifer thickness); p w The recharge water density; C w The specific heat capacity of the recharge water; The thermal capacity per unit volume of the thermal reservoir, i.e. ; In the formula, The porosity of the thermal reservoir, p r The density of the thermal reservoir rock, C r The specific heat capacity of the thermal reservoir rock.

[0025] The existing formula for calculating the reasonable well-pumping well spacing of the well-pumping system can be obtained by formula transformation: ; The above formula is the existing formula for calculating the reasonable well-pumping well spacing of the well-pumping system, and the basic framework of the formula for calculating the reasonable well-pumping well spacing of the well-pumping system is established accordingly: ; In the formula, r 0 represents the reasonable well-pumping well spacing of the well-pumping system, Q The recharge water volume, t The design operation life of the well-pumping system, p The density of the thermal reservoir (including geothermal water and reservoir matrix), C The specific heat capacity of the thermal reservoir (including geothermal water and reservoir matrix), f The function operation represents that the reasonable well-pumping well spacing of the well-pumping system is a function of the recharge water volume Q , the design operation life of the well-pumping system t , the effective thickness of the thermal reservoir H , the density of the thermal reservoir p , and the specific heat capacity of the thermal reservoir C .

[0026] Based on the basic framework of the formula for calculating the reasonable well-pumping well spacing of the well-pumping system, combined with the principle of energy conservation (the first law of thermodynamics), a more clear physical meaning method is adopted to derive the theoretical formula for calculating the reasonable well-pumping well spacing of the well-pumping system, which is more in line with the process of heat extraction and migration of recharge low-temperature water in the thermal reservoir; The formula for calculating the reasonable well-pumping well spacing of the well-pumping system is mainly derived based on the evolution and distribution law of the geothermal field under the condition of multi-year recharge: The thermal reservoir is homogeneous and isotropic, the roof depth and thickness are the same, the permeability and porosity are stable; In geothermal extraction and irrigation projects, the extraction wells and the reinjection wells have the same extraction stratum, the same well structure and depth, and the filter pipes all pass through the geothermal reservoir. The initial temperature of the thermal reservoir is the water extraction temperature. T 0, Recharge water temperature T 1 refers to the temperature of the filter pipe section of the recharge well during continuous recharge; Low-temperature water mixes with high-temperature geothermal water in the reservoir and draws heat from the geothermal water in the pores and fissures of the reservoir rocks, creating a temperature gradient between the migrating cold front and the reinjection well. The temperature from the leading edge of the cold front to the reinjection well is T 1≤ T ≤ T 0, where, T This represents the temperature at any point within the geothermal reservoir. Outside the leading edge of the cold front, the temperature is the initial temperature of the reservoir, i.e., the same water intake temperature. T 0. Without interference from reinjected low-temperature water, a thermal breakthrough is considered to have occurred until the cold front reaches the production well. Figure 2 As shown, red indicates high-temperature water in thermal storage, and blue indicates low-temperature water in recharge.

[0027] The derivation process of the theoretical calculation formula for the reasonable well spacing in a well-injection and injection system includes: Using the reinjection wellbore as the low-temperature source, T = T 1. Under the drive of high head pressure, the reinjected low-temperature water moves from the reinjection well to the surrounding area, so as to... x A temperature gradient increases with radius. When a low-temperature cold front ( T = T 0) Transported to the production well, i.e. x = r When the temperature of the well drops at 0°C, it is considered a thermal breakthrough. Figure 3 As shown.

[0028] Based on the mathematical concept of differential calculus, the distance between the production and injection wells is divided into countless infinitesimal equal parts, and the distance from the injection well on the plane is calculated. x d x The heat lost by the wide annular body, such as Figure 4 The process of obtaining the result is as follows: d x Temperature of point T dx : ; d x Temperature drop : ; Right now: ; dx The heat lost by the point is E lost-dx : ; According to the integral concept, the heat lost by the well to d x The heat lost by the thermal reservoir column of radius r is: ; That is: ; In the formula: ; Then: ; In the formula, E lost The heat lost by the well to d x The heat lost by the thermal reservoir column of radius r, that is, the total heat lost by the thermal reservoir, H The effective thickness of the thermal reservoir, T 0 is the temperature of the water taken, T 1 is the temperature of the recharged water, r 0 is the moving radius of the low-temperature front, p The density of the thermal reservoir, C The specific heat capacity of the thermal reservoir.

[0029] Further, the total heat lost by the thermal reservoir at the time of thermal breakthrough includes: When x = r 0, thermal breakthrough occurs, at which time the heat lost by the thermal reservoir is: ; In the formula, E lost The total heat lost by the thermal reservoir.

[0030] Geothermal water is extracted from T 0 temperature, T 1 temperature recharged, and the heat extracted by the surface heat exchange system E used That is: ; In the formula, t The design and operation life of the well extraction and recharge system.

[0031] According to the foregoing, the heat lost by the thermal reservoir E lost is equal to the heat extracted by the surface heat exchange system E used That is: ; The above formula meets the relationship between the basic framework variables , and a calculation model of the well spacing is derived by formula transformation: .

[0032] By comparing the calculation model of the well spacing and the existing calculation formula, it can be found that the two formulas only differ in the constant term coefficient. The theoretical calculation result of the well spacing of the well production and injection system considering the heat exchange between the hot and cold water in the thermal reservoir derived in the embodiment is times the calculation result of the existing calculation formula, and has greater safety redundancy.

[0033] When the well spacing calculation model is used for actual calculation, the effective thickness of the thermal reservoir H , the density of the thermal reservoir p (including geothermal water and reservoir matrix), the specific heat capacity of the thermal reservoir C (including geothermal water and reservoir matrix), and other formula calculation required parameters need to be determined according to the thermal reservoir developed by the well production and injection system; Based on the collected regional stratum lithology, aquifer hydraulic properties, burial characteristics, thermal reservoir characteristics, and other geothermal geological data and the permeability coefficient, the hydraulic conductivity coefficient, the water storage coefficient, the specific heat, the thermal conductivity coefficient, the density, and other hydrodynamic and thermal physical parameters, the parameter assignment of the theoretical calculation formula of the thermal breakthrough critical time is carried out. The above geological, hydrogeological, and geothermal geological data can be obtained from the existing geological and mineral exploration departments and the petroleum department.

[0034] Based on the established well spacing calculation model, the reasonable well spacing under the conditions of different well production and injection amounts and the design operation time of the well production and injection system is directly calculated.

[0035] The embodiment also provides a reasonable well spacing calculation system of the geothermal well production and injection system constrained by the thermal breakthrough of the well production and injection system, which comprises: A parameter acquisition module is configured to acquire the thermal reservoir parameters of a to-be-measured region; A model construction module is configured to construct a well spacing calculation model based on the law of conservation of energy, wherein the well spacing calculation model is obtained by deducing an existing reasonable well spacing calculation formula of the geothermal well production and injection system; A result output module is configured to input the thermal reservoir parameters into the well spacing calculation model for processing to obtain the well spacing.

[0036] In order to more clearly express the technical scheme of the present application, the following provides specific embodiments for introducing the scheme: Step one: determining the basic framework of the well production and injection system reasonable well spacing calculation formula and its applicable conditions; The applicable conditions include: The thermal reservoir is horizontal and equal in thickness, the overburden and underlying rock are impermeable, the initial temperature of the aquifer and the overburden and underlying rock are the same, and the temperature of the overburden and the underlying rock of the thermal reservoir is constant; The production and recharge flow are stable, the recharge water temperature is stable, the horizontal and vertical heat conduction of the thermal reservoir is ignored, the water and rock in the thermal reservoir instantaneously reach thermal equilibrium, and the temperature of the rock and water is the same; The heat transfer of heat conduction can be ignored relative to convective heat transfer, and after ignoring the heat conduction term, the cold front surface will migrate radially with the recharge well as the center.

[0037] The basic framework is: The existing formula for calculating the reasonable well spacing of the geothermal well production and recharge system is: ; In the formula, r 0 is the reasonable well spacing of the geothermal well production and recharge system; Q is the recharge water volume; t is the design production time of the well production and recharge system; H is the effective thickness of the thermal reservoir (i.e. the thickness of the aquifer); p w is the recharge water density; C w is the specific heat capacity of the recharge water; represents the heat capacity per unit volume of the thermal reservoir, i.e. ; In the formula, is the porosity of the thermal reservoir, p r is the density of the thermal reservoir rock, C r is the specific heat capacity of the thermal reservoir rock.

[0038] According to this, the basic framework of the formula for calculating the reasonable well spacing of the well production and recharge system is established: ; In the formula, f is a function operation, which means that the reasonable well spacing of the well production and recharge system is a function of the recharge water volume Q , the design operation period of the well production and recharge system t , the effective thickness of the thermal reservoir H , the density of the thermal reservoir p , and the specific heat capacity of the thermal reservoir C .

[0039] Step 2: Derivation of the formula for calculating the reasonable well spacing of the well production and recharge system and determination of the applicable conditions; Based on the basic framework of the formula for calculating the reasonable distance between the production and injection wells, combined with the principle of energy conservation (the first law of thermodynamics), a more reasonable method is used to derive the theoretical formula for calculating the reasonable distance between the production and injection wells, which is more consistent with the process of heat extraction and migration of low-temperature water in the thermal reservoir and has a clearer physical meaning.

[0040] The applicable conditions include: The thermal reservoir is homogeneous and isotropic, with the same roof depth and thickness, stable permeability and porosity; The production layer of the production well and the injection layer of the injection well are the same in the geothermal production and injection project, and the well structure, well depth, and filter pipe are the same and pass through the thermal reservoir; The initial temperature of the thermal reservoir is the water temperature T 0, the temperature of the injected water is T 1, and the temperature of the filter pipe section of the injection well is The low-temperature water mixes with the high-temperature geothermal water in the thermal reservoir and extracts the heat contained in the geothermal water and rocks in the pore and fissure of the thermal reservoir, forming a temperature gradient decreasing from the cold front to the injection well; The temperature of the cold front front edge is T 1≤ T ≤ T 0, where T is the temperature of any point in the thermal reservoir. Outside the cold front front edge, the temperature is the initial temperature of the thermal reservoir T 0, i.e., the same water temperature T 0, which is not disturbed by the injected low-temperature water, until the cold front reaches the production well, which is considered to have occurred thermal breakthrough; The derivation process is as follows: The injection wellbore is a low-temperature source point, T = T 1, and the injected low-temperature water migrates to the surrounding under the driving of high water head pressure, forming a temperature gradient increasing with x as the radius.

[0041] When the low-temperature cold front ( T = T 0) migrates to the production well, i.e., x = r 0, the temperature of the production well decreases, which is considered to have occurred thermal breakthrough, as shown in Figure 3 .

[0042] According to the concept of mathematical differentiation, the distance between the production and injection wells is divided into countless small equal parts, and the heat loss of the d x width ring-shaped body at a distance of x from the injection well is calculated, as follows: The temperature of the d x point is T dx : ; d x Point of reduced temperature : ; That is: ; d x Point of lost heat E lost-dx is: ; According to the integral concept, the well to d x The heat lost by the thermal reservoir column of radius d is: ; That is: ; In the formula: ; Then: ; When x = r 0, that is, when thermal breakthrough occurs, the heat lost by the thermal reservoir is: ; In the formula, E lost is the total heat lost by the thermal reservoir.

[0043] Geothermal water is extracted from T 0 temperature, T 1 temperature re-injection, the heat extracted by the surface heat exchange system E used That is: ; In the formula, t is the design operating life of the well production and injection system.

[0044] According to the foregoing, the heat lost in the thermal reservoir E lost is equal to the heat extracted by the surface heat exchange system E used That is: ; The well spacing calculation model is derived: .

[0045] Step three: determine the basic parameters of the reasonable well spacing calculation formula of the geothermal well production and injection system; The parameter assignment of the theoretical calculation formula of the thermal breakthrough critical time is performed based on the collected geothermal geological data such as regional stratum lithology, aquifer hydraulic property, burial characteristics and thermal reservoir characteristics and the hydrodynamic and thermal physical parameters such as permeability coefficient, transmissivity, water storage coefficient, specific heat, thermal conductivity and density.

[0046] thermal reservoir effective thickness H and thermal reservoir porosity ϕ The reinjection water density p w , the specific heat capacity of the reinjection water C w , the density of the thermal reservoir rock p r and the specific heat capacity of the thermal reservoir rock C r can be obtained directly from the geothermal well completion report.

[0047] Step four: calculation of the reasonable production and injection well spacing of the well pair injection system; Based on the established production and injection well spacing calculation model, the reasonable production and injection well spacing under the conditions of different production and injection amounts and design operation time of the well pair injection system is directly calculated.

[0048] For the thermal reservoir effective thickness H of the typical well pair injection system = 120 m, the design operation time t of the well pair injection system = 50 years, the production and injection amount Q = 70 m 3 / h, the reinjection water density p w = 985 kg / m 3 , the specific heat capacity of the reinjection water C w = 4178 J / (kg·℃), the thermal reservoir porosity ϕ = 0.3, the density of the thermal reservoir rock p r = 2000 kg / m 3 , and the specific heat capacity of the thermal reservoir rock C r = 890 J / (kg·℃), the reasonable production and injection well spacing of the well pair injection system can be directly calculated as 636.2 m.

[0049] Compared with the previous thermal breakthrough critical time calculation formula, the production and injection well spacing calculation model provided in the embodiment considers the heat exchange between the cold water and the hot water after the cold water is injected into the thermal reservoir, improves the prediction accuracy of the thermal breakthrough time of the production well, and realizes more accurate prediction of the thermal breakthrough time of the production well.

[0050] The above merely provides the preferred embodiments of the present application, and the protection scope of the present application is not limited thereto, and any changes or substitutions within the technical scope disclosed by the present application should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A method for calculating the reasonable well spacing for geothermal well production and irrigation systems to address thermal exceedance constraints, characterized in that... include: Obtain the thermal reservoir parameters of the area to be tested; A calculation model for the spacing between production and irrigation wells is constructed based on the law of conservation of energy. The calculation model is derived from the existing formula for calculating the reasonable spacing between production and irrigation wells in geothermal well production and irrigation systems. The thermal reservoir parameters are input into the production-injection well spacing calculation model for processing to obtain the production-injection well spacing.

2. The method for calculating the reasonable well spacing for geothermal well production and irrigation systems in accordance with claim 1, characterized in that, The parameters of the geothermal reservoir include the effective thickness of the geothermal reservoir, the density of the geothermal reservoir, the specific heat capacity of the reinjection water, the reinjection water volume, and the specific heat capacity of the geothermal reservoir. The effective thickness of the geothermal reservoir is obtained from the geothermal well completion report, while the density of the geothermal reservoir, the specific heat capacity of the reinjection water, the reinjection water volume, and the specific heat capacity of the geothermal reservoir are all obtained through experimental testing.

3. The method for calculating the reasonable well spacing for geothermal well production and irrigation systems in accordance with claim 1, characterized in that, This paper derives the formula for calculating the reasonable well spacing in existing geothermal well production and irrigation systems, including: The recharge well is regarded as a low temperature source point, that is, the low temperature water recharged forms a radial temperature gradient in the thermal reservoir; By using a differential model, the distance between the production and injection wells is divided into several small equal parts, and the distance to the reinjection well is calculated. x d x The heat loss of the wide annular structure is calculated, and the total heat loss of the thermal reservoir during thermal breakthrough is calculated by integration. Based on the principle that the heat extracted by the surface heat exchange system is equal to the total heat loss of the thermal reservoir, the calculation model for the well spacing is derived.

4. The method for calculating the reasonable well spacing for geothermal well production and irrigation systems in accordance with claim 3, characterized in that, Calculate the distance from the recharge well x The heat lost by the annular structure is: ； In the formula, E lost-dx For the distance from the injection well x The heat lost by the annular structure, H The effective thickness of the thermal reservoir, T 0 represents the water temperature. T 1 represents the recharge water temperature. r 0 represents the optimal spacing between geothermal wells for the extraction and irrigation system. ρ Density of the thermal reservoir C This represents the specific heat capacity of the thermal reservoir.

5. The method for calculating the reasonable well spacing for geothermal well production and irrigation systems in accordance with claim 4, characterized in that, The calculation of the total heat loss of the reservoir during the thermal breakthrough includes: when When a thermal breakthrough occurs, the heat lost by the thermal reservoir is: ； In the formula, E lost This represents the total heat loss from the thermal reservoir.

6. The method for calculating the reasonable well spacing for geothermal well production and irrigation systems in accordance with claim 5, characterized in that, The heat extracted by the surface heat exchange system is: ； In the formula, E used The heat extracted by the surface heat exchange system Q This refers to the amount of water used for recharge. t To determine the design service life of the well production and irrigation system, ρ w For the density of the recharge water, C w This refers to the specific heat capacity of the reinjection water.

7. The method for calculating the reasonable well spacing for geothermal well production and irrigation systems in accordance with claim 1, characterized in that, The calculation model for the spacing between the production and irrigation wells is as follows: ； In the formula, r 0 represents the optimal spacing between geothermal wells for the extraction and irrigation system. ρ w For the density of the recharge water, C w For the specific heat capacity of the reinjection water, Q This refers to the amount of water used for recharge. t To determine the design service life of the well production and irrigation system, H The effective thickness of the thermal reservoir, This indicates the heat capacity per unit volume of the thermal reservoir.

8. The method for calculating the reasonable well spacing for geothermal well production and irrigation systems in accordance with claim 7, characterized in that, The thermal capacity per unit volume of the thermal reservoir for: ； In the formula, For the porosity of the thermal reservoir, ρ r The density of the thermal reservoir rock, C r This represents the specific heat capacity of the thermal reservoir rock.

9. The method for calculating the reasonable well spacing for geothermal well production and irrigation systems in accordance with claim 1, characterized in that, The conditions under which the calculation model for the spacing between production and irrigation wells is applicable include: The thermal reservoir is homogeneous and isotropic, with the same burial depth and thickness of the top plate, and stable permeability and porosity. The production well and the injection well have the same stratigraphic position, well structure and well depth, and the filter pipes of both wells pass through the thermal reservoir. The reinjection water temperature is constant, and the initial thermal storage temperature is constant.

10. A system for calculating the reasonable well spacing for geothermal well production and irrigation systems to address thermal exceedance constraints, used to implement the method described in any one of claims 1-9, characterized in that, include: Parameter acquisition module: used to acquire the thermal reservoir parameters of the area to be tested; Model building module: used to build a calculation model for the spacing between production and irrigation wells based on the law of conservation of energy. The calculation model for the spacing between production and irrigation wells is obtained by deriving the reasonable calculation formula for the spacing between production and irrigation wells in existing geothermal well production and irrigation systems. The result output module is used to input the thermal reservoir parameters into the production-injection well spacing calculation model for processing, and obtain the production-injection well spacing.

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