Method for calculating allowable exploitation quantity of cavity tubular heat storage geothermal resource development and utilization project

Abstract

The invention discloses a method for calculating the allowable mining quantity of a cavity-tube-shaped heat storage geothermal resource development and utilization project, and the method comprises the following steps: S1, on the basis of geothermal geological survey of a geothermal field, finding out the distribution characteristics of a main heat control and water guide structure; and S2, according to actual geothermal resource development and utilization engineering requirements, the minimum exploited geothermal water temperature value meeting the actual development and utilization engineering requirements is determined. And S3, calculating the maximum allowable water level burial depth meeting the temperature condition of the exploited geothermal water in the step S2 through a data statistical analysis method, and setting the maximum allowable water level burial depth as the maximum water level burial depth value. And S4, establishing an initial model and a prediction model by adopting a parameter model. And S5, when the corresponding water level fitted by adjusting the actual mining quantity is lowered to the water level calculated in the step S3, the actual mining quantity fitted at the stage is the allowable mining quantity value meeting the actual mining temperature limiting condition. The calculation result better meets the actual production and exploitation requirements, and sustainable development and utilization of geothermal resources are protected.

Description

Technical Field

[0001] The invention belongs to the technical field of geological exploration, and in particular relates to a method for calculating the allowable extraction volume for a geothermal resource development and utilization project of a cavity tubular heat storage. Background Art

[0002] The existing technology calculates the allowable extraction volume of geothermal resources in the cavity-shaped heat reservoir controlled by fault structure by analytical method, numerical method, heat storage method, etc., but the above methods all have their own limitations. For example, for geothermal fields with cavity-shaped heat reservoirs, since the geothermal fluids are confined in the heat reservoir space with cavity-shaped distribution, the specific influence radius of the geothermal fluid cannot be given when the analytical method is used for calculation. Similarly, since the geothermal resources of cavity-shaped heat reservoirs come from the deep crust, the existing exploration technology cannot clearly determine the thermal reservoir thickness of the geothermal fluid in the vein-shaped heat reservoir. Karst heat reservoirs also cannot give effective influence radius data. The calculation parameters such as the heat reservoir thickness, heat reservoir area, and influence radius required for the calculation cannot be accurately obtained. Some parameters usually use empirical parameters, and the calculation results cannot truly reflect the allowable extraction volume of the actual geothermal field. Summary of the invention

[0003] The present invention provides a method for calculating the allowable extraction volume for geothermal resource development and utilization projects of cavity tubular heat storage. The use of this calculation method is based on the analytical calculation of the allowable extraction volume of geothermal fields under the conditions of the maximum allowable water level burial depth under the conditions of development and utilization temperature limitations. It can greatly improve the evaluation accuracy of the recoverable resource volume of geothermal wells, make the calculation results more in line with the actual production and exploitation needs, and thus protect the sustainable development and utilization of geothermal resources.

[0004] To achieve the above object, the present invention provides the following technical solution: a method for calculating the allowable extraction volume for a geothermal resource development and utilization project of a tubular heat storage, characterized in that the method for calculating the allowable extraction volume comprises the following steps: S1: Based on the geothermal geological survey of the geothermal field, the distribution characteristics of the main heat-controlling and water-conducting structures are identified, and special geothermal monitoring wells are selected in the core area with the highest temperature and the largest water volume of the geothermal field to conduct long-term dynamic monitoring of the water level and temperature of the geothermal fluid. At the same time, the actual production volume of the geothermal wells in various geothermal fields is regularly counted in long series and dynamic statistics, and summarized in the database; S2: According to the actual needs of geothermal resource development and utilization projects, determine the minimum geothermal water temperature value that meets the actual needs of the development and utilization project. This temperature value is a dynamic value that changes with the actual project needs; S3: Summarize and organize the data in the database obtained in step S1, use the real and reliable long-sequence observation data of geothermal field water level, water temperature, and production volume, calculate the maximum allowable water level burial depth that meets the geothermal water temperature conditions of step S2 through data statistical analysis, and set it as the maximum water level burial depth value under the long-term large-scale production state of the well; S4: using the parameter model to preliminarily fit the data in the database obtained in step S1, and establish an initial model and a prediction model; S5: After verifying the model established in step S4, the recoverable resources of the geothermal field under the maximum allowable water level calculated in step S3 are continuously simulated and calculated by continuously increasing the actual extraction volume of the geothermal field in the model. When the corresponding water level fitted by adjusting the actual extraction volume drops to the water level calculated in step S3, the actual extraction volume fitted in this stage is the allowable extraction volume value that meets the actual extraction temperature limit conditions.

[0005] Preferably, in step S1, long-term dynamic monitoring of the water level and water temperature of the geothermal fluid is performed, and long-sequence dynamic statistics of the actual production of thermal wells in various geothermal fields are performed for a period of more than or equal to ten years; the frequency of long-term dynamic monitoring of the water level and water temperature of the geothermal fluid is at least six times a month; and long-sequence dynamic statistics of the actual production of thermal wells in various geothermal fields are performed at least once a month.

[0006] Preferably, the minimum temperature value of the extracted geothermal water in step S2 is defined according to the actual application scenario of the geothermal resources in the development and utilization project; the actual application scenario of the geothermal resources is ultimately defined according to the utilization purpose of different development and utilization projects.

[0007] Preferably, the final limitation based on the utilization purpose of different development and utilization projects includes limiting the minimum water temperature to 43°C when used for floor heating, limiting the minimum water temperature to above 50°C when used for radiator heating, and limiting the water temperature to 38°C when used for bathing.

[0008] Preferably, the step S3 calculates the maximum allowable water level depth that meets the geothermal water temperature conditions of step S2 by a data statistical analysis method, the data statistical analysis method includes linear fitting and least squares curve fitting, and comprehensively selects the equation with the highest fitting coefficient for fitting, thereby determining the maximum water level depth under the limited minimum mining temperature.

[0009] Preferably, the software for establishing the initial model and the prediction model in step S4 includes COMSOL, VARFLOW, and LUMPFIT, and the software with the highest fitting coefficient is selected to establish the initial model and the prediction model.

[0010] Preferably, the actual mining volume is adjusted in step S5 by adjusting the mining volume in an increasing or decreasing manner; the mining volume is increased or decreased synchronously based on the monthly average mining volume, thereby minimizing calculation errors.

[0011] Compared with the prior art, the present invention has the following beneficial effects: 1. The method for calculating the allowable extraction volume of the utilization project is to calculate the maximum allowable extraction volume that meets the actual production needs of the geothermal resource development and utilization project based on the long-term water level, water temperature and water volume monitoring data and the minimum extraction temperature limited by the actual development and utilization project, so as to provide a reference basis for the sustainable development and utilization of geothermal resources; 2. The analysis and calculation of the allowable extraction volume of geothermal fields under the conditions of the maximum allowable water level burial depth under the conditions of development and utilization temperature limitation can greatly improve the evaluation accuracy of the recoverable resources of geothermal wells, making the calculation results more in line with the actual production and exploitation needs, thereby protecting the sustainable development and utilization of geothermal resources; Other features and advantages of the present disclosure will become apparent from the following detailed description of exemplary embodiments of the present disclosure with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure or related technologies, the drawings required for use in the embodiments or related technical descriptions will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0013] Figure 1 It is a schematic diagram of the spatial form of the cavity-tube heat storage of the present invention and the difficulty in calculating the allowable extraction volume of geothermal resources in the prior art; Figure 2 It is a schematic diagram of the steps of the calculation method of the present invention; Figure 3 Step S1 of the calculation method embodiment of the present invention is a dynamic statistical chart of long-series observation of water level, water temperature and extraction volume for many years of geothermal resource development and utilization; Figure 4 This is a schematic diagram of determining the maximum water level burial depth under the minimum mining temperature and limiting the optimal fitting curve in step S3 of the calculation method embodiment of the present invention; Figure 5 This is a comparison chart of prediction model determination and analysis in step S4 of the calculation method embodiment of the present invention; Figure 6 The maximum allowable mining volume comparison chart under the maximum allowable water level burial depth is fitted in step S5 of the calculation method embodiment of the present invention; DETAILED DESCRIPTION

[0014] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0015] Unless otherwise specifically stated, the relative arrangement of the parts and steps described in these embodiments, numerical expressions and numerical values ​​do not limit the scope of the present invention. At the same time, it should be understood that, for ease of description, the sizes of the various parts shown in the accompanying drawings are not drawn according to the actual proportional relationship. The technology, method and equipment known to ordinary technicians in the relevant field may not be discussed in detail, but in appropriate cases, the technology, method and equipment should be regarded as a part of the authorization specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters represent similar items in the following drawings, so once a certain item is defined in an accompanying drawing, it does not need to be further discussed in subsequent drawings.

[0016] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used here to describe the spatial positional relationship between a device or feature and other devices or features as shown in the figure. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figure. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0017] See also Figure 1-6 The present invention provides a technical solution: a method for calculating the allowable extraction volume for a geothermal resource development and utilization project of a tubular heat storage, the method comprising the following steps: S1: Based on the geothermal geological survey of the geothermal field, the distribution characteristics of the main heat-controlling and water-conducting structures are identified, and special geothermal monitoring wells are selected in the core area with the highest temperature and the largest water volume of the geothermal field to conduct long-term dynamic monitoring of the water level and temperature of the geothermal fluid. At the same time, the actual production volume of the geothermal wells in various geothermal fields is regularly counted in long series and dynamic statistics, and summarized in the database; S2: According to the actual needs of geothermal resource development and utilization projects, determine the minimum geothermal water temperature value that meets the actual needs of the development and utilization project. This temperature value is a dynamic value that changes with the actual project needs; S3: Summarize and organize the data in the database obtained in step S1, use the real and reliable long-sequence observation data of geothermal field water level, water temperature, and production volume, calculate the maximum allowable water level burial depth that meets the geothermal water temperature conditions of step S2 through data statistical analysis, and set it as the maximum water level burial depth value under the long-term large-scale production state of the well; S4: using the parameter model to preliminarily fit the data in the database obtained in step S1, and establish an initial model and a prediction model; S5: After verifying the model established in step S4, the recoverable resources of the geothermal field under the maximum allowable water level calculated in step S3 are continuously simulated and calculated by continuously increasing the actual extraction volume of the geothermal field in the model. When the corresponding water level fitted by adjusting the actual extraction volume drops to the water level calculated in step S3, the actual extraction volume fitted in this stage is the allowable extraction volume value that meets the actual extraction temperature limit conditions.

[0018] In step S1, long-term dynamic monitoring of the water level and water temperature of the geothermal fluid is performed, and long-sequence dynamic statistics of the actual production of thermal wells in various geothermal fields are performed for a period of more than or equal to ten years; the frequency of long-term dynamic monitoring of the water level and water temperature of the geothermal fluid is at least six times a month; long-sequence dynamic statistics of the actual production of thermal wells in various geothermal fields are performed at least once a month.

[0019] The minimum temperature of the extracted geothermal water in step S2 is limited according to the actual application scenario of geothermal resources in the development and utilization project; the actual application scenario of geothermal resources is ultimately limited by the utilization purpose of different development and utilization projects. The ultimate limitation based on the utilization purpose of different development and utilization projects includes limiting the minimum water temperature to 43°C when used for floor heating, limiting the minimum water temperature to above 50°C for radiator heating, and limiting the water temperature to 38°C for bathing.

[0020] Step S3 calculates the maximum allowable water level depth that meets the geothermal water temperature conditions of step S2 through data statistical analysis. The data statistical analysis method includes linear fitting and least squares curve fitting, and comprehensively selects the equation with the highest fitting coefficient for fitting, thereby determining the maximum water level depth under the limited minimum mining temperature.

[0021] The software used to establish the initial model and the prediction model in step S4 includes COMSOL, VARFLOW, and LUMPFIT, and the software with the highest fitting coefficient is selected to establish the initial model and the prediction model.

[0022] In step S5, the actual mining volume is adjusted in an increasing or decreasing manner; the mining volume is increased or decreased synchronously based on the monthly average mining volume, thereby minimizing calculation errors. Example

[0023] Step S1, conduct long-sequence dynamic observation of the water level, water temperature and extraction volume of a geothermal resource area, and draw a curve chart of the statistical data from 1992 to 2016, such as Figure 3 As shown; Steps S2 and S3, the geothermal resources determined in the area are used for hot spring bathing, and the minimum exploitation temperature is determined to be 38°C. Through a variety of data statistical analysis methods, including linear fitting, least squares curve fitting, etc., the maximum allowable water level burial depth under the condition of geothermal water temperature of 38°C is calculated, and it is set as the maximum burial depth of the water level in the state of long-term large-scale exploitation of the well to be 20m. Figure 4 shown.

[0024] Step S4, using COMSOL, VARFLOW, LUMPFIT and other parameter models, preliminarily fit the data in the database obtained in step S1, and found that LUMPFIT is the software with the highest fitting coefficient, so it is used to establish the initial model and the prediction model, and to make the comparison curves of water level depth and mining volume and date respectively. The specific comparison curves are shown in Figure 5 shown.

[0025] Step S5, in the LUMPFIT model, by continuously increasing the actual extraction value of the geothermal field, continuously simulate and calculate the recoverable resources of the geothermal field under the maximum allowable water level burial depth of 20m calculated in step S3. When the corresponding water level fitted by adjusting the actual extraction amount drops to the water level 20m calculated in step S3, the actual extraction amount fitted in this stage is the allowable extraction amount value under the actual extraction temperature limit condition. The specific fitting process and the comparison chart of the maximum mining volume obtained are shown in Figure 6 shown.

[0026] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for calculating the allowable extraction volume for a geothermal resource development and utilization project of a cavity-tube heat storage, characterized in that: The method for calculating the allowable production volume comprises the following steps: S1: Based on the geothermal geological survey of the geothermal field, the distribution characteristics of the main heat-controlling and water-conducting structures are identified, and special geothermal monitoring wells are selected in the core area with the highest temperature and the largest water volume of the geothermal field to conduct long-term dynamic monitoring of the water level and temperature of the geothermal fluid. At the same time, the actual production volume of the geothermal wells in various geothermal fields is regularly counted in long series and dynamic statistics, and summarized in the database; S2: According to the actual needs of geothermal resource development and utilization projects, determine the minimum geothermal water temperature value that meets the actual needs of the development and utilization project. This temperature value is a dynamic value that changes with the actual project needs; S3: Summarize and organize the data in the database obtained in step S1, use the real and reliable long-sequence observation data of geothermal field water level, water temperature, and production volume, calculate the maximum allowable water level burial depth that meets the geothermal water temperature conditions of step S2 through data statistical analysis, and set it as the maximum water level burial depth value under the long-term large-scale production state of the well; S4: using the parameter model to preliminarily fit the data in the database obtained in step S1, and establish an initial model and a prediction model; S5: After verifying the model established in step S4, the recoverable resources of the geothermal field under the maximum allowable water level calculated in step S3 are continuously simulated by continuously increasing the actual extraction volume of the geothermal field in the model. When the corresponding water level fitted by adjusting the actual extraction volume drops to the water level calculated in step S3, the actual extraction volume fitted in this stage is the allowable extraction volume value that meets the actual extraction temperature limit conditions.

2. A method for calculating the allowable extraction volume for a geothermal resource development and utilization project of a tubular heat storage according to claim 1, characterized in that: In step S1, long-term dynamic monitoring of the water level and water temperature of the geothermal fluid is performed, and long-sequence dynamic statistics of the actual production of thermal wells in various geothermal fields are performed for a period of more than or equal to ten years; the frequency of long-term dynamic monitoring of the water level and water temperature of the geothermal fluid is at least six times a month; and long-sequence dynamic statistics of the actual production of thermal wells in various geothermal fields are performed at least once a month.

3. A method for calculating the allowable extraction volume for a geothermal resource development and utilization project of a tubular heat storage according to claim 1, characterized in that: The minimum geothermal water temperature value in step S2 is limited according to the actual geothermal resource application scenario of the development and utilization project; The actual geothermal resource application scenarios are ultimately defined based on the utilization purposes of different development and utilization projects.

4. A method for calculating the allowable extraction volume for a geothermal resource development and utilization project of a tubular heat storage according to claim 3, characterized in that: The final limitation based on the purpose of different development and utilization projects includes that when used for floor heating, the minimum water temperature is limited to 43°C, when used for radiator heating, the minimum water temperature is limited to above 50°C, and when used for bathing, the water temperature is limited to 38°C.

5. The method for calculating the allowable extraction volume for the development and utilization project of geothermal resources in a cavity-tube heat storage according to claim 1 is characterized by: The step S3 calculates the maximum allowable water level depth that meets the geothermal water temperature conditions of step S2 by using a data statistical analysis method. The data statistical analysis method includes linear fitting and least squares curve fitting, and comprehensively selects the equation with the highest fitting coefficient for fitting, thereby determining the maximum water level depth under the limited minimum mining temperature.

6. A method for calculating the allowable extraction volume for a geothermal resource development and utilization project of a tubular heat storage according to claim 1, characterized in that: The software used to establish the initial model and the prediction model in step S4 includes COMSOL, VARFLOW, and LUMPFIT, and the software with the highest fitting coefficient is selected to establish the initial model and the prediction model.

7. The method for calculating the allowable extraction volume for the development and utilization project of geothermal resources in a cavity-tube heat storage according to claim 1 is characterized by: The actual mining volume in step S5 is adjusted by increasing or decreasing the mining volume; the mining volume is increased or decreased synchronously based on the monthly average mining volume, thereby minimizing calculation errors.

Images