Segmented structure analysis method and terminal device based on medium-depth or deep geothermal well

Abstract

The application discloses a kind of based on middle-deep or deep geothermal well segmented structure analysis method and terminal equipment, belong to geothermal energy development technical field, can solve middle-deep, deep geothermal well because of flow resistance estimation deviation leads to design failure, cause system overall energy efficiency low problem.The method comprises the following steps: S1, determine the multiple sets of structure design parameters of geothermal well, and calculate the total resistance of each group of structure design parameters corresponding to geothermal well side;S2, according to each geothermal well side total resistance determines the type of corresponding geothermal well side circulating water pump, and calculates the pump operating cost of circulating water pump;S3, calculate the center tube cost expense and geothermal well heating revenue expense corresponding to each group of structure design parameters;S4, according to the total resistance of multiple sets of structure design parameters corresponding to geothermal well side, pump operating cost, center tube cost expense and geothermal well heating revenue expense, determine the optimal structure parameters of geothermal well.The application is used for the structure design of middle-deep geothermal well.

Description

Technical Field

[0001] This invention relates to a method and terminal equipment for segmented structural analysis of medium-deep or deep geothermal wells, belonging to the field of geothermal energy development technology. Background Technology

[0002] Geothermal energy, as a stable, clean, and renewable baseload energy source, is receiving increasing attention globally. Against the backdrop of accelerated low-carbon energy transition, my country has a wide distribution of medium-deep geothermal energy resources (buried at depths of 2000-3000 meters). However, due to currently immature development and utilization technologies, its resource potential has not been fully realized. While deep geothermal energy (buried at depths greater than 3000 meters) has even greater resource potential, it remains largely in the scientific research and preliminary exploration stages due to limitations in key technologies such as efficient heat extraction, with very few practical engineering applications.

[0003] Medium-deep and deep geothermal coaxial casing heat exchange systems have become a key emerging technology for development due to their advantages such as "heat extraction without water extraction, minimal environmental disturbance, and safe operation." However, their efficient design and reliable operation and maintenance heavily rely on accurate prediction of the complex flow processes within the wellbore. Existing methods for calculating flow resistance are insufficient to accurately calculate the flow resistance of this system under special design conditions, such as different burial depths, segmented structures, and fluid property variations with temperature. Given that the investment in a single medium-deep or deep geothermal well can reach tens of millions of yuan, design errors due to inaccurate flow resistance estimations will pose significant risks: on the one hand, insufficient pump power selection will lead to insufficient circulation flow, significantly reducing heat extraction efficiency; on the other hand, excessive pump power will result in equipment redundancy, increased energy consumption, and even overload damage. All of these problems may lead to low overall system energy efficiency, and in severe cases, even project failure. Summary of the Invention

[0004] This invention provides a method and terminal equipment for segmented structural analysis of medium-deep or deep geothermal wells, which can solve the problem of design errors caused by flow resistance estimation deviations in medium-deep and deep geothermal wells, resulting in low overall system energy efficiency and even project failure in severe cases.

[0005] On one hand, the present invention provides a method for segmented structural analysis of medium-deep or deep geothermal wells, wherein the geothermal well includes a variable-diameter wellbore and a variable-diameter central pipe, and the geothermal well is divided into multiple open segments according to the gap width between the variable-diameter wellbore and the variable-diameter central pipe. The method includes:

[0006] S1. Determine multiple sets of structural design parameters for the geothermal well and calculate the total resistance on the geothermal well side corresponding to each set of structural design parameters;

[0007] S2. Determine the type of circulating water pump corresponding to each geothermal well based on the total resistance on each geothermal well side, and calculate the pump operating cost of the circulating water pump.

[0008] S3. Calculate the cost of the central pipe and the revenue from geothermal well heating corresponding to each set of structural design parameters.

[0009] S4. Based on the total resistance of the geothermal well side, pump operating costs, central pipe costs, and geothermal well heating revenue costs corresponding to multiple sets of structural design parameters, determine the optimal structural parameters of the geothermal well.

[0010] Optionally, calculate the total resistance on the geothermal well side for each set of structural design parameters, specifically including:

[0011] Calculate the total resistance of the geothermal well corresponding to each set of structural design parameters;

[0012] Calculate the total resistance of the machine room pipeline network and the total resistance of the equipment of the geothermal well, and determine the total resistance of the geothermal well side corresponding to each set of structural design parameters based on the total resistance of the geothermal well, the total resistance of the machine room pipeline network and the total resistance of the equipment.

[0013] Optionally, calculate the total resistance of the geothermal well corresponding to each set of structural design parameters, specifically including:

[0014] Calculate the total resistance of the inner cavity pipe, the total resistance of the annulus pipe, and the resistance of the bottom center pipe of the geothermal well corresponding to each set of structural design parameters;

[0015] The total resistance of the geothermal well corresponding to each set of structural design parameters is obtained by summing the total resistance of the inner cavity pipe, the total resistance of the annular pipe, and the resistance of the bottom center pipe.

[0016] Optionally, calculate the total resistance of the internal piping of the geothermal well corresponding to each set of structural design parameters, specifically including:

[0017] Calculate the total friction resistance and total local resistance of the inner cavity pipe in the geothermal well corresponding to each set of structural design parameters, and sum the total friction resistance and total local resistance of the inner cavity pipe to obtain the total resistance of the inner cavity pipe of the corresponding geothermal well.

[0018] Optionally, calculate the total friction resistance along the inner pipe of the geothermal well corresponding to each set of structural design parameters, specifically including:

[0019] Calculate the Reynolds number of the inner cavity of the inner cavity pipe in each section of the geothermal well corresponding to each set of structural design parameters, and determine the hydraulic resistance coefficient of the inner cavity of the corresponding section based on the inner cavity Reynolds number;

[0020] The friction resistance of the corresponding open section of the inner cavity pipe is determined based on the hydraulic resistance coefficient of the inner cavity, and the friction resistance of all open sections of the inner cavity pipe is summed to obtain the total friction resistance of the inner cavity pipe in the corresponding geothermal well.

[0021] Optionally, calculate the total local resistance of the internal pipes in the geothermal well corresponding to each set of structural design parameters, specifically including:

[0022] Calculate the variable diameter local resistance coefficient of the inner cavity pipe in each section of the geothermal well corresponding to each set of structural design parameters;

[0023] The local resistance of the inner pipe in each opening segment is determined based on the local resistance coefficient of the variable diameter and the water flow velocity of the corresponding opening segment. The local resistance of the inner pipe in all opening segments is summed to obtain the total local resistance of the inner pipe in the corresponding geothermal well.

[0024] Optionally, calculate the total resistance of the annular pipe in the geothermal well corresponding to each set of structural design parameters, specifically including:

[0025] Calculate the total friction resistance, total coupling resistance, and total diameter change resistance of the annular pipe in the geothermal well corresponding to each set of structural design parameters, and sum the total friction resistance, total coupling resistance, and total diameter change resistance of the annular pipe to obtain the total resistance of the annular pipe in the corresponding geothermal well.

[0026] Optionally, calculate the total friction resistance of the annulus pipe in the geothermal well corresponding to each set of structural design parameters, specifically including:

[0027] Calculate the annular Reynolds number of the annular pipe in each open section of the geothermal well corresponding to each set of structural design parameters, and determine the annular hydraulic resistance coefficient of the corresponding open section based on the annular Reynolds number;

[0028] The friction resistance of the corresponding open section of the annulus pipe is determined based on the annulus hydraulic resistance coefficient, and the friction resistance of all open sections of the annulus pipe is summed to obtain the total friction resistance of the annulus pipe in the corresponding geothermal well.

[0029] Optionally, S4 specifically includes:

[0030] The total revenue of the geothermal well is determined based on the pump operating cost, central pipe cost, and geothermal well heating revenue cost corresponding to each set of structural design parameters.

[0031] The optimal segmented structural parameters of the geothermal well are determined based on the total resistance and total revenue cost corresponding to multiple sets of structural design parameters.

[0032] On the other hand, the present invention provides a terminal device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the steps of any of the above-described methods for segmented structural analysis of medium-deep or deep geothermal wells.

[0033] The beneficial effects that this invention can produce include:

[0034] The present invention provides a segmented structural analysis method based on medium-deep or deep geothermal wells. It calculates the total resistance of the geothermal well-side system by segmenting and summarizing the data, and optimizes the selection of circulating water pumps based on this. Then, it comprehensively calculates the operating costs of the water pumps and the cost of the central pipe, and combines the benefits generated by the heat extraction of the system to evaluate the economic benefits of different structural design parameter schemes, so as to support scientific decision-making and system optimization.

[0035] The present invention provides a segmented structural analysis method for medium-deep or deep geothermal wells. Based on refined structural design parameters input by the user (such as well shaft dimensions, outer diameter and wall thickness of the central pipe, length of each segment, and pipe wall friction coefficient), and combined with fluid mechanics theory, the Reynolds number is first calculated. This invention accurately identifies the flow state region (laminar flow zone, hydraulically smooth zone, mixed friction zone, or completely rough zone), thereby precisely determining the hydraulic friction resistance coefficient. Based on this, it calculates the frictional and local resistance of each region segment by segment, ultimately summing up the total flow resistance of the entire well under different depths and segment configurations. This invention follows the logical path of "technical parameters - equipment selection - economic evaluation," conducting economic benefit assessments of different technical solutions to support scientific decision-making and system optimization.

[0036] The present invention provides a segmented structure analysis method based on medium-deep or deep geothermal wells. The calculation results can support several key engineering decisions: first, optimizing the structural matching between the well diameter and the central pipe diameter; second, quantitatively analyzing the impact of the inner wall roughness of the central pipe on system resistance; third, providing a basis for formulating the optimal circulation flow control strategy; fourth, providing accurate and reliable data support for the selection of circulation pump flow rate and head, effectively avoiding problems such as "oversized pump for undersized load" or "insufficient capacity," and ensuring efficient and economical system operation; and fifth, comprehensively analyzing economic efficiency and optimizing the segmented structure. Therefore, this invention can quickly and accurately calculate the flow resistance of coaxial casing heat exchange systems in medium-deep and deep geothermal wells under complex conditions such as different burial depths, segmented structures, and fluid properties varying with temperature. This provides reliable basic data for the selection and operation of circulating water pumps on the geothermal well side, ensuring that the system reaches the design flow rate and guarantees its stable and efficient operation. This method is not only the core support for the optimization of system technical solutions and key parameters, but also a key prerequisite for effectively controlling investment risks and ensuring the successful implementation of projects. It is of great significance for the efficient, sustainable, and economical operation of heating systems in medium-deep and deep coaxial casing geothermal wells. Attached Figure Description

[0037] Figure 1 A flowchart of a method for segmented structural analysis of medium-deep or deep geothermal wells provided in an embodiment of the present invention;

[0038] Figure 2 This is a schematic diagram of a segmented structural model of a medium-deep or deep geothermal well provided for an embodiment of the present invention. Detailed implementation manners

[0039] The present invention will be described in detail below in conjunction with embodiments, but the present invention is not limited to these embodiments.

[0040] An embodiment of the present invention provides a method for analyzing the segmented structure of a medium-depth or deep geothermal well, as Figure 1 and Figure 2 shown. The geothermal well includes a variable-diameter wellbore and a variable-diameter central pipe. The geothermal well is divided into multiple open sections according to the gap width between the variable-diameter wellbore and the variable-diameter central pipe. The method includes:

[0041] S1. Determine multiple groups of structural design parameters of the geothermal well, and calculate the total side resistance of the geothermal well corresponding to each group of structural design parameters.

[0042] The medium-depth or deep geothermal well adopts a closed-loop circulation mode of "annular injection and central pipe reflux": after the low-temperature circulating medium is pressurized by the circulating water pump, it first enters the annular pipeline between the outer casing and the central pipe, and is transported downward to the bottom of the well; it enters the inner cavity of the central pipe through the bottom turning device. The medium absorbs the heat of the surrounding rock formation during the descending process, the temperature rises, and returns to the ground through the central pipe; subsequently, the high-temperature medium enters the heat pump system to release heat for heating, and the cooled medium is pumped into the geothermal well again by the circulating water pump to complete continuous circulation.

[0043] The variable-diameter wellbore structure is divided into three well sections: the first open section, the second open section, and the third open section according to the drilling process; correspondingly, the design of the variable-diameter central pipe is subdivided into the first open section, the second open section, the second open section, the third open section, and the third open section, as Figure 2 shown, to match the geological conditions and engineering design requirements of different well sections. To support refined design, the present invention sets the following parameters:

[0044] (1) The well diameter and depth of each well section (the first open section, the second open section, and the third open section);

[0045] (2) The outer diameter, wall thickness, and service length of the central pipe for each corresponding segmented section of the central pipe (the first open section, the second open section, the second open section, the third open section, the third open section, which will be described below with section).

[0046] The wellbore structure and the central pipe configuration can be customized section by section according to the actual geological data and engineering requirements. The design process is based on the thermal physical properties of the formation, structural characteristics, hydrogeological parameters, and construction factors, and high-precision hydraulic and thermal coupling calculations are carried out based on this model to optimize the system performance and improve the heat extraction efficiency and economy.

[0047] The calculation of the total resistance on the geothermal well side for each set of structural design parameters specifically includes:

[0048] (1) Calculate the total resistance of the geothermal well corresponding to each set of structural design parameters.

[0049] Specifically, it includes:

[0050] Calculate the total resistance of the inner cavity pipe, the total resistance of the annular pipe, and the resistance of the bottom center pipe of the geothermal well corresponding to each set of structural design parameters.

[0051] The total resistance of the geothermal well corresponding to each set of structural design parameters is obtained by summing the total resistance of the inner cavity pipe, the total resistance of the annular pipe, and the resistance of the bottom center pipe.

[0052] Specifically, the calculation of the total resistance of the inner cavity pipe of the geothermal well corresponding to each set of structural design parameters involves: calculating the total friction resistance and total local resistance of the inner cavity pipe of the geothermal well corresponding to each set of structural design parameters, and summing the total friction resistance and total local resistance of the inner cavity pipe to obtain the total resistance of the inner cavity pipe of the corresponding geothermal well.

[0053] 1) Calculate the total friction resistance along the inner pipe of the geothermal well corresponding to each set of structural design parameters, specifically including:

[0054] Calculate the Reynolds number of the inner cavity of the inner cavity pipe in each section of the geothermal well corresponding to each set of structural design parameters, and determine the hydraulic resistance coefficient of the inner cavity of the corresponding section based on the Reynolds number.

[0055] The friction resistance of the corresponding open section of the inner cavity pipe is determined based on the hydraulic resistance coefficient of the inner cavity, and the friction resistance of all open sections of the inner cavity pipe is summed to obtain the total friction resistance of the inner cavity pipe in the corresponding geothermal well.

[0056] 2) Calculate the total local resistance of the internal pipes in the geothermal well corresponding to each set of structural design parameters, specifically including:

[0057] Calculate the variable diameter local resistance coefficient of the inner cavity pipe in each section of the geothermal well corresponding to each set of structural design parameters;

[0058] The local resistance of the inner pipe in each opening section is determined based on the local resistance coefficient of the variable diameter and the water flow velocity of the corresponding opening section. The local resistance of the inner pipe in all opening sections is then summed to obtain the total local resistance of the inner pipe in the corresponding geothermal well.

[0059] Specifically, calculating the total resistance of the annular pipe in the geothermal well corresponding to each set of structural design parameters includes:

[0060] Calculate the total friction resistance, total coupling resistance, and total diameter change resistance of the annular pipe in the geothermal well corresponding to each set of structural design parameters, and sum the total friction resistance, total coupling resistance, and total diameter change resistance of the annular pipe to obtain the total resistance of the annular pipe in the corresponding geothermal well.

[0061] The above calculation of the total friction resistance of the annulus pipe in the geothermal well corresponding to each set of structural design parameters specifically includes:

[0062] Calculate the annular Reynolds number of the annular pipe in each open section of the geothermal well corresponding to each set of structural design parameters, and determine the annular hydraulic resistance coefficient of the corresponding open section based on the annular Reynolds number;

[0063] The friction resistance of the corresponding open section of the annulus pipe is determined based on the annulus hydraulic resistance coefficient, and the friction resistance of all open sections of the annulus pipe is summed to obtain the total friction resistance of the annulus pipe in the corresponding geothermal well.

[0064] (2) Calculate the total resistance of the machine room network and the total resistance of the equipment of the geothermal well, and determine the total resistance of the geothermal well side corresponding to each set of structural design parameters based on the total resistance of the geothermal well, the total resistance of the machine room network and the total resistance of the equipment.

[0065] The calculation process of the total resistance on the side of a geothermal well is described in detail below.

[0066] 1. Calculate the total resistance of the internal pipes of the geothermal well.

[0067] (1) Calculate the total friction resistance along the inner cavity of the pipe. .

[0068] 1) Inner cavity tube Friction along the section :

[0069] (1)

[0070] (2)

[0071] (3)

[0072] In the formula: for Friction resistance along the pipe within the section; for Hydraulic resistance coefficient of the pipe within the section; for Length of the central section of the pipe; The inner diameter of the tube within the segment; The average density of the medium in the inner cavity of the pipe; for Fluid velocity within the segment of the pipe; The flow rate of the fluid; for The area of ​​the inner cavity of the tube. (See attached diagram) Figure 2 As shown, Option 1 is acceptable. , , , .

[0073] 2) Hydraulic resistance coefficient of the inner cavity pipe calculate.

[0074] ①Intraluminal Reynolds number Calculation:

[0075] (4)

[0076] In the formula: for Reynolds number in the segment ; for Fluid velocity within the segment of the pipe; for Inner diameter of the segment's internal cavity; for The kinematic viscosity coefficient of water within the segment of the pipe; see Table 1 below for details.

[0077] Table 1. Kinematic Viscosity Coefficient

[0078]

[0079] ② Hydraulic resistance coefficient of the inner cavity pipe calculate:

[0080] a. This is a laminar flow region;

[0081] (5)

[0082] b. This is a hydraulically smooth region;

[0083] (6)

[0084] (7)

[0085] in hour,

[0086] (8)

[0087] c. This is a region of mixed friction;

[0088] (9)

[0089] d. , which is a rough region;

[0090] (10)

[0091] In the formula: The equivalent absolute roughness of the inner wall of the tube; for Reynolds number in the segment ; for Inner diameter of the segment's internal cavity; for Hydraulic resistance coefficient of the pipe within the segment.

[0092] ③ Total frictional resistance along the inner cavity of the pipe calculate:

[0093] (11)

[0094] In the formula: This represents the total frictional resistance along the inner cavity of the tube. The friction resistance along the opening section of the inner cavity pipe; For the inner cavity tube, two openings Friction resistance along the section; For the inner cavity tube, two openings Friction resistance along the section; Three-section internal tube Friction resistance along the section; Three-section internal tube The frictional resistance along the section.

[0095] (2) Calculate the total local resistance of the internal tube. .

[0096] The local resistance of the internal pipe is mainly the resistance from the diameter change along the water flow direction. The diameter change is handled according to the "sudden expansion" structure. The local resistance coefficient of the diameter change is calculated by the following formula, and the corresponding flow velocity head is: (Sudden contraction resistance head) , , .

[0097] (12)

[0098] (13)

[0099] (14)

[0100] (15)

[0101] (16)

[0102] In the formula: It is a three-section The pipe diameter and area before and after the sudden contraction; It is a three-section The pipe diameter and area before and after the sudden expansion; For two openings The pipe diameter and area before and after the sudden expansion; For two openings The pipe diameter and area before and after the sudden expansion; It is a three-section Local resistance coefficient of the cavity with varying diameter; It is a three-section Local resistance coefficient of the cavity with varying diameter; For two openings Local resistance coefficient of the cavity with varying diameter; For two openings Local resistance coefficient of the cavity with varying diameter; The density of the water flow; It is a three-section Water flow velocity within the segment cavity; For two openings Water flow velocity within the segment cavity; For two openings Water flow velocity within the segment cavity; This represents the total local resistance of the internal cavity.

[0103] (3) Calculate the total resistance of the internal tube. .

[0104] (17)

[0105] In the formula: This represents the total resistance of the internal tube. This represents the total local resistance of the internal cavity tube; This represents the total frictional resistance along the inner cavity of the pipe.

[0106] 2. Calculate the total resistance of the annulus of the geothermal well.

[0107] (1) Calculate the total friction resistance of the annular pipe .

[0108] Hydraulic radius of annular pipe The value is defined as the ratio of the cross-sectional area of ​​the flow path to the wetted perimeter.

[0109] (18)

[0110] (19)

[0111] (20)

[0112] (twenty one)

[0113] In the formula: for Outer diameter of the well casing; for Duanjing casing wall thickness; for Inner diameter of the well casing; for Outer diameter of the central tube section; for Hydraulic radius of the annular pipe section; for Equivalent diameter of the annular pipe section.

[0114] 1) Annular Pipeline Friction resistance along the section calculate:

[0115] (twenty two)

[0116] (twenty three)

[0117] (twenty four)

[0118] In the formula: for Friction resistance along the annular pipeline; for Hydraulic resistance coefficient of the annular pipe section; for Length of the central section of the pipe; The average density of the medium; for Fluid velocity in the annular pipe section; for Equivalent diameter of the annular pipe section; The flow rate of the fluid; for Area of ​​the annular pipe section; for Inner diameter of the well casing; for Outer diameter of the central pipe of the section.

[0119] 2) Hydraulic resistance coefficient of annular pipe calculate.

[0120] ① Circular Reynolds Number Calculation:

[0121] (25)

[0122] In the formula: For the ring Reynolds number ; for Fluid velocity within the segment of the pipe; for Equivalent diameter of the annular pipe section; for The kinematic viscosity coefficient of water within the segment of the pipe.

[0123] ② Hydraulic resistance coefficient of annular pipe calculate:

[0124] a. This is a laminar flow region;

[0125] (26)

[0126] b. This is a hydraulically smooth region;

[0127] (27)

[0128] (28)

[0129] in hour,

[0130] (29)

[0131] c. This is a region of mixed friction;

[0132] (30)

[0133] d. , which is a rough region;

[0134] (31)

[0135] In the formula: The hydraulic resistance coefficient of the annular pipe; for Segment Reynolds Number ; The equivalent absolute roughness of the annular pipe wall is 0.06 mm, assuming it is a seamless steel pipe. This is the equivalent diameter of the annular pipe.

[0136] 3) Total frictional resistance of the annular pipeline calculate:

[0137] (32)

[0138] In the formula: The total frictional resistance of the annular pipeline; The friction resistance along the opening section of the annular pipeline; For the second opening of the annular pipeline Friction resistance along the section; For the second opening of the annular pipeline Friction resistance along the section; Three-way opening for annular pipeline Friction resistance along the section; Three-way opening for annular pipeline The frictional resistance along the section.

[0139] (2) Calculate the total resistance of the couplings in the annular pipe. .

[0140] 1) The resistance of each coupling segment is calculated using the following formula:

[0141] (33)

[0142] In the formula: for Segment coupling resistance; for Number of segment couplings; for Section coupling resistance coefficient; The density of the water flow; for Water flow velocity at the joint.

[0143] 2) Total coupling resistance of the annular pipeline .

[0144] (34)

[0145] In the formula: The total resistance of the couplings in the annular pipeline; For the resistance of the coupling in the annular pipeline; For the second opening of the annular pipeline Segment coupling resistance; For the second opening of the annular pipeline Segment coupling resistance; Three-way opening for annular pipeline Segment coupling resistance; Three-way opening for annular pipeline Section coupling resistance.

[0146] (3) Calculate the total resistance of the annulus of the geothermal well. .

[0147] (35)

[0148] In the formula: The total resistance of the annular pipeline; The total frictional resistance of the annular pipeline; The total resistance of the annular pipe coupling; This represents the total resistance of the annular pipe with varying diameter.

[0149] 3. Calculate the resistance of the central pipe at the bottom of the geothermal well. .

[0150] The resistance of the center tube at the bottom of the well is calculated using the following formula:

[0151] (36)

[0152] In the formula: The local resistance coefficient at the bottom of the central tube; The density of the water flow; It is a three-section The velocity of water flow in the cavity.

[0153] 4. Calculate the total resistance of the geothermal well .

[0154] (37)

[0155] In the formula: This represents the total resistance of the geothermal well. This represents the total resistance of the internal tube. The total resistance of the annular pipeline; This represents the resistance of the central tube at the bottom of the well.

[0156] 5. Calculate the total resistance of the geothermal well's machine room piping network. .

[0157] (38)

[0158] (39)

[0159] (40)

[0160] (41)

[0161] (42)

[0162] (43)

[0163] In the formula: The local drag coefficient for variable diameter is recommended to be 0.5; This represents the total number of variable diameters. The local resistance coefficient for the tee is 1, which is recommended. This represents the total number of tees; The local resistance coefficient for the elbow is recommended to be 0.5. This represents the total number of elbows; The local resistance coefficient of the heat meter is recommended to be 1.5; This represents the total number of heat meters. The recommended value for the local resistance coefficient of the valve is 0.5. This represents the total number of valves. for The recommended local resistance coefficient for this type of filter is 8. for Total number of type filters; The recommended value for the local resistance coefficient of the flexible connector is 2. This represents the total number of flexible connections. The recommended local resistance coefficient for the check valve is 7. Total number of check valves; This represents the sum of the local resistance coefficients of the computer room and outdoor pipelines; This represents the total resistance between the computer room and the outdoor pipe network. This is the hydraulic resistance coefficient between the computer room and the outdoor pipeline; This refers to the inner diameter of the pipes connecting the computer room and the outdoor area. This refers to the outer diameter of the pipes connecting the computer room and the outside. For the wall thickness of the pipes between the computer room and the outside; The equivalent absolute roughness of the pipes between the computer room and the outdoor area is 0.5 mm, as defined in the "Practical Heating and Air Conditioning Design Manual (Second Edition)". This refers to the length of the pipeline between the computer room and the outdoor area; The density of the water flow; The fluid velocity in the pipes connecting the computer room and the outdoor area; The flow rate of the fluid; This refers to the area of ​​the computer room and outdoor pipelines.

[0164] 6. Calculate the total equipment resistance of the geothermal well. .

[0165] (44)

[0166] In the formula, This represents the total resistance of the equipment. For the equipment's heat pump resistance; For the resistance of the equipment plate; For resistance to other equipment.

[0167] 7. Calculate the total resistance on the side of the geothermal well. .

[0168] (45)

[0169] In the formula: This represents the total resistance on the geothermal well side. This represents the total resistance of the geothermal well. The total resistance of the computer room piping network; This represents the total resistance of the equipment.

[0170] S2. Determine the type of circulating water pump corresponding to each geothermal well based on the total resistance on each geothermal well side, and calculate the pump operating cost of the circulating water pump.

[0171] (1) Determine the type of circulating water pump for the geothermal side.

[0172] Shaft power of geothermal circulating water pump It can be calculated using the following formula:

[0173] (46)

[0174] (47)

[0175] (48)

[0176] (49)

[0177] In the formula: These are the performance parameters of the circulating water pump on the side of the geothermal well. The safety factor for the capacity of the circulating water pump motor on the geothermal well side; The density of the water flow; The flow rate of the fluid; This refers to the flow rate of the circulating water pump on the side of the geothermal well. The shaft power of the circulating water pump on the side of the geothermal well; Power of the circulating water pump on the side of the geothermal well; This represents the total resistance on the geothermal well side. This refers to the head of the circulating water pump on the side of the geothermal well.

[0178] (2) Determine the operating cost of the geothermal circulating water pump.

[0179] (50)

[0180] In the formula: This refers to the unit price of electricity. Operating life (in years); Number of days of operation; This refers to the number of times the device is run per day. Power of the circulating water pump on the side of the geothermal well; This refers to the operating costs of the circulating water pump on the side of the geothermal well.

[0181] S3. Calculate the cost of the central pipe and the revenue from geothermal well heating corresponding to each set of structural design parameters.

[0182] (1) Determine the cost of the central pipe:

[0183] (51)

[0184] In the formula: Centralized management of costs and expenses; This refers to the length of the center section of the pipe. For two openings Length of the central section of the pipe; For two openings Length of the central section of the pipe; It is a three-section Length of the central section of the pipe; It is a three-section Length of the central section of the pipe; The unit price per meter of the central pipeline in a single section; For two openings Unit price per meter of central pipeline; For two openings Unit price per meter of central pipeline; It is a three-section Unit price per meter of central pipeline; It is a three-section Price per meter of pipeline in the center section.

[0185] (2) Determine the revenue and cost of geothermal well heating.

[0186] (52)

[0187] In the formula: This refers to the unit price of heat supply; Total heat supply; This refers to the revenue and expenses generated from heating supply.

[0188] In practical applications, based on the segmented structure model of geothermal wells, by setting key parameters such as well body structure dimensions, central pipe diameter and wall thickness, length of each segment, circulation flow rate and formation thermal properties, geothermal heat simulation software can be used to simulate and calculate the total heat supply under different well depths, different structural dimensions and different flow rates.

[0189] S4. Based on the total resistance of the geothermal well side, pump operating costs, central pipe costs, and geothermal well heating revenue costs corresponding to multiple sets of structural design parameters, determine the optimal structural parameters of the geothermal well.

[0190] Specifically, it includes:

[0191] The total revenue of a geothermal well is determined based on the pump operating costs, central pipe costs, and geothermal well heating revenue costs corresponding to each set of structural design parameters.

[0192] The optimal structural parameters of the geothermal well are determined based on the total resistance and total revenue cost corresponding to multiple sets of structural design parameters.

[0193] For medium-deep and deep geothermal well systems, the design process is based on formation thermal properties, structural characteristics, and hydrogeological parameters, and involves segmented wellbore structure design. This invention uses a five-segment structure as a benchmark (the number of segments can be dynamically adjusted according to formation properties). By setting key parameters such as well depth, number of segments, length of each segment, wellbore structural dimensions, central pipe diameter and wall thickness, and circulation flow rate, the system calculates core indicators such as total well-side resistance, geothermal-side circulating water pump operating costs, central pipe costs, and heating revenue costs. Finally, through multi-dimensional comparative analysis and a comprehensive evaluation of thermal performance and economics, the optimal geothermal well system structural design scheme is selected, achieving a balance between technical feasibility and economic rationality.

[0194] This invention expands the coverage of medium-deep to deep wellbore, adopts segmented parametric modeling, and accurately determines the flow state, thereby achieving precise calculation of system resistance and providing a core basis for multi-scheme comparison and optimization.

[0195] 1. Expanded Algorithm Coverage: The algorithm is designed for coaxial heat exchange systems in medium-deep (2000~3000 meters) and deep (>3000 meters) wells, covering the entire well depth range. The algorithm can calculate friction loss, local resistance, and total pressure drop based on different well depths, pipe diameter combinations, fluid properties (temperature, viscosity, density), and flow conditions.

[0196] 2. Segmented Parametric Model Setting: Breaking through the limitations of traditional uniform parametric models, a segmented parametric modeling method is adopted. Based on the detailed design of the geothermal well, the well body is divided into 5 continuous segments, and each segment is assigned corresponding engineering parameters, including well depth, well diameter, central pipe diameter, wall thickness, circulating medium temperature and flow rate, etc., thereby achieving a precise digital mapping of the actual physical structure and properties of the geothermal well.

[0197] 3. Precise identification and calculation of flow state regions in the heating field: Unlike conventional heating pipe networks that simply use mixed friction zones to calculate flow resistance, this invention is based on the five-segment division of geothermal wells, setting parameters such as roughness, pipe diameter, and wall thickness. Combined with different flow conditions, it can accurately identify the flow state regions of the annulus and inner cavity (laminar flow region, hydraulically smooth region, mixed friction region, or completely rough region), thereby achieving precise calculation of water flow resistance.

[0198] 4. Provides strong basis for multi-scheme comparison and optimization of segmented heat exchange: It can quickly evaluate the impact of different central pipe / well diameter combinations, insulation structure, laying length, roughness and flow rate on system resistance. At the same time, combined with economic evaluation, it helps to select the best technical solution, improve system energy efficiency, and provide a reliable basis for comparison and selection of multiple design schemes.

[0199] Another embodiment of the present invention provides a terminal device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the steps of the segmented structure analysis method based on medium-deep or deep geothermal wells as described above.

[0200] The aforementioned terminal equipment provides key design optimization tools for medium-deep and deep geothermal energy projects, with the following specific functions:

[0201] (1) Accurate calculation of flow resistance under different well depth conditions.

[0202] For medium-deep and deep geothermal wells, it supports the calculation of friction resistance, local resistance and total pressure drop under different well depths, pipe diameter combinations, fluid properties (temperature, viscosity, density) and flow rates, ensuring the accuracy of design parameters.

[0203] (2) Segmented structure multi-scheme comparison and optimization.

[0204] It can quickly assess the impact of different combinations of central / outer pipe diameters, insulation structures, laying lengths, and flow rates on system resistance, assist in the selection of optimal technical solutions, and provide a basis for comparison and selection of multiple design schemes.

[0205] (3) Analysis of the influence of the roughness of the central tube.

[0206] The system analyzes the influence of pipe wall roughness of central and outer pipes of different materials on fluid flow resistance, further improving the accuracy of hydraulic calculations and the predictive ability of long-term system reliability.

[0207] (4) Operation control strategy.

[0208] Determining the optimal injection flow rate and temperature provides a data foundation for intelligent control and energy-saving operation, optimizes system operating parameters, and improves energy efficiency.

[0209] (5) A circulating water pump is preferred.

[0210] Based on the system's hydraulic calculations, the flow rate and head parameters of the circulating water pumps are optimized to avoid reduced heat extraction efficiency due to insufficient pump capacity or energy waste due to over-configuration. This provides a quantitative basis for pipe diameter selection, pump set configuration, and operating parameter optimization, avoiding over-design or under-capacity.

[0211] (6) Improve system energy efficiency.

[0212] By accurately calculating resistance loss, the energy consumption of the circulating pump is reduced, the overall heat extraction efficiency is improved, and the high efficiency of the system in actual operation is ensured.

[0213] (7) Economic analysis.

[0214] Based on the segmented geothermal system structure, this study comprehensively considers the operating costs of the circulating water pump and the initial investment cost of the central pipe, as well as the revenue generated by the system's heat extraction. It conducts a full life-cycle economic benefit assessment of different technical solutions to provide a quantitative basis for optimized design and decision-making.

[0215] (8) Promote standardization and engineering.

[0216] To develop reusable and scalable design tools to facilitate the standardized implementation of deep geothermal projects and promote the standardization and large-scale application of technologies.

[0217] This invention not only improves the scientific design level of deep geothermal projects, but also provides reliable technical support for subsequent similar projects, promoting the efficient development and utilization of deep geothermal energy.

[0218] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and all fall within the scope of the technical solution.

Claims

1. A method for segmented structural analysis of medium-deep or deep geothermal wells, characterized in that, The geothermal well includes a variable-diameter wellbore and a variable-diameter central pipe. The geothermal well is divided into multiple sections according to the gap width between the variable-diameter wellbore and the variable-diameter central pipe. The method includes: S1. Determine multiple sets of structural design parameters for the geothermal well and calculate the total resistance on the geothermal well side corresponding to each set of structural design parameters; S2. Determine the type of circulating water pump corresponding to each geothermal well based on the total resistance on each geothermal well side, and calculate the pump operating cost of the circulating water pump. S3. Calculate the cost of the central pipe and the revenue from geothermal well heating corresponding to each set of structural design parameters. S4. Based on the total resistance of the geothermal well side, pump operating costs, central pipe costs, and geothermal well heating revenue costs corresponding to multiple sets of structural design parameters, determine the optimal structural parameters of the geothermal well. The calculation of the total geothermal well-side resistance corresponding to each set of structural design parameters in S1 specifically includes: Calculate the total resistance of the inner cavity pipe, the total resistance of the annulus pipe, and the resistance of the bottom center pipe of the geothermal well corresponding to each set of structural design parameters; and sum the total resistance of the inner cavity pipe, the total resistance of the annulus pipe, and the resistance of the bottom center pipe of the geothermal well corresponding to each set of structural design parameters to obtain the total resistance of the geothermal well corresponding to each set of structural design parameters. Calculate the total resistance of the machine room piping network and the total resistance of the equipment of the geothermal well, and determine the total resistance of the geothermal well side corresponding to each set of structural design parameters based on the total resistance of the geothermal well, the total resistance of the machine room piping network and the total resistance of the equipment; The calculation of the total resistance of the internal pipes of the geothermal well corresponding to each set of structural design parameters specifically includes: Calculate the Reynolds number of the inner cavity of the inner cavity pipe in each section of the geothermal well corresponding to each set of structural design parameters, and determine the hydraulic resistance coefficient of the inner cavity of the corresponding section based on the inner cavity Reynolds number; The friction resistance of the corresponding open section of the inner cavity pipe is determined based on the hydraulic resistance coefficient of the inner cavity. The friction resistance of all open sections of the inner cavity pipe is summed to obtain the total friction resistance of the inner cavity pipe in the corresponding geothermal well. The variable diameter local resistance coefficient of the inner cavity pipe in each open section of the geothermal well corresponding to each set of structural design parameters is calculated. The local resistance of the inner cavity pipe in each open section is determined based on the variable diameter local resistance coefficient and the water flow velocity of the corresponding open section of the inner cavity pipe. The local resistance of all open sections of the inner cavity pipe is summed to obtain the total local resistance of the inner cavity pipe in the corresponding geothermal well. The total friction resistance and the total local resistance of the inner cavity pipe are then summed to obtain the total resistance of the inner cavity pipe in the corresponding geothermal well. The calculation of the total resistance of the annular pipe in the geothermal well corresponding to each set of structural design parameters specifically includes: Calculate the annular Reynolds number of the annular pipe in each section of the geothermal well corresponding to each set of structural design parameters, determine the annular hydraulic resistance coefficient of the corresponding section based on the annular Reynolds number, determine the friction resistance of the annular pipe in the corresponding section based on the annular hydraulic resistance coefficient, and sum the friction resistance of the annular pipe in all sections to obtain the total friction resistance of the annular pipe in the corresponding geothermal well. Calculate the total friction resistance and total diameter change resistance of the annular pipe in the geothermal well corresponding to each set of structural design parameters, and sum the total friction resistance, total friction resistance, and total diameter change resistance of the annular pipe to obtain the total resistance of the annular pipe in the corresponding geothermal well.

2. The method according to claim 1, characterized in that, S4 specifically includes: The total revenue of the geothermal well is determined based on the pump operating cost, central pipe cost, and geothermal well heating revenue cost corresponding to each set of structural design parameters. The optimal segmented structural parameters of the geothermal well are determined based on the total resistance and total revenue cost corresponding to multiple sets of structural design parameters.

3. A terminal device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the steps of the segmented structure analysis method based on medium-deep or deep geothermal wells as described in claim 1 or 2.

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