L-shaped well same-well extraction and irrigation method and system

Abstract

The invention relates to a same-well extraction and irrigation method and system for an L-shaped well. The system comprises at least one well group, each well group at least comprises two L-shaped wells arranged at intervals, and well pipes are arranged in the L-shaped wells; the at least one heat compensation system is matched with the well group; the control device is arranged corresponding to the well group, the heat supply input end is connected with the water outlet end of the L-shaped well, the heat supply output end is connected with a lower-stage unit, the heat compensation input end is connected with the heat compensation system, the heat compensation output end is connected with the well pipe, and the control device is configured to decide the working mode of the L-shaped well in the same group and the regulation and control state of the well pipe based on the heat supply output end and the water outlet temperature of each well. The method specifically comprises the steps of judging the working mode and the recovery mode of the L-shaped well, selecting the recovery mode and adjusting the water outlet flow. The collecting modules are arranged at the water outlet ends of the L-shaped wells and the heat supply output end of the control device. Through well group binding, real-time monitoring and intelligent regulation and control, parallel heat collection and recovery are achieved, and heat supply continuity and energy recycling are guaranteed.

Description

Technical Field

[0001] This invention relates to the field of geothermal technology, specifically to a method and system for simultaneous extraction and irrigation of L-shaped wells. Background Technology

[0002] L-shaped wells are widely used in the extraction and injection of medium- and low-temperature geothermal resources due to their advantages such as small footprint and reasonable heat exchange path. Their core working principle is as follows: a casing well is run into the well, consisting of a water injection pipe and a heat exchange pipe arranged concentrically. The low-temperature working fluid enters from the water injection pipe in the center of the casing, completes heat exchange in the high-temperature formation through the bottom pipe, and then flows out through the heat exchange pipe on the outside of the water injection pipe for utilization. However, existing L-shaped well extraction and injection systems have the following inherent defects: First, continuous heat extraction leads to a "cold accumulation" phenomenon in the surrounding formation, meaning the temperature field continuously decreases and the heat exchange efficiency declines year by year. Second, the natural recovery rate of geothermal fields is much slower than the extraction rate (the natural recovery cycle usually takes several years). If the well group needs to be restored, heat extraction must be interrupted, leading to unstable heating. Existing heat replenishment technologies mostly involve "directly injecting hot water into the reinjection well," which easily dissipates heat and cannot be paralleled with the heat extraction process, making it difficult to achieve a balance between uninterrupted heating and efficient recovery. Therefore, there is an urgent need in this field for an L-shaped well simultaneous extraction and irrigation technology that can achieve parallel heat extraction and restoration and ensure continuous heating supply. Summary of the Invention

[0003] To overcome the shortcomings of existing L-shaped well simultaneous production and irrigation systems, according to one aspect of this application, an L-shaped well simultaneous production and irrigation system is provided, the system comprising: At least one well group, each well group including at least two L-shaped wells spaced apart, wherein well pipes are installed in the L-shaped wells; At least one heat replenishment system is provided in conjunction with the well group; A control device is provided corresponding to the well group. The heating input terminal of the control device is connected to the water outlet terminal of the L-shaped well in the same group. The heating output terminal of the control device is connected to the lower-level unit. The heat replenishment input terminal of the control device is connected to the heat replenishment system. The heat replenishment output terminal of the control device is connected to the well pipe of the L-shaped well. The data acquisition module is installed at the water outlet of each L-shaped well and the heating output of the control device to monitor the water temperature and flow rate of the L-shaped well and the control device in real time. The control device is configured to: Based on the temperature at the heating output end and the outlet water temperature of each L-shaped well, a decision is made on whether the L-shaped wells are in parallel operation mode or single well operation mode, and the well pipes of the same group of L-shaped wells are adjusted. The control status includes determining the working mode and recovery mode of the L-shaped well, selecting the recovery mode of the L-shaped well, and adjusting the outflow rate of the L-shaped well.

[0004] Preferably, the well casing includes a heat outlet pipe and a heat exchange pipe arranged concentrically from the inside out; The heat exchange tube is installed close to the well wall and a recovery layer is provided between it and the well wall. An isolation tube is provided between the heat exchange tube and the heat outlet tube. The recovery layer is a heat-conducting structure. The outer wall of the recovery layer is in close contact with the well wall. The recovery layer is connected to the outside of the heat exchange tube. A first heat replenishment inlet is provided at the top of the recovery layer. The isolation tube is concentrically arranged with the heat outlet tube and spaced apart on the outside of the heat outlet tube. The two ends of the isolation tube are respectively sealed to the outer ends of the two ends of the heat outlet tube. A second heat replenishment inlet and a heat replenishment return outlet are provided at the sealed connection of the top ends of the isolation tube and the heat outlet tube. The first heat input port and the second heat input port are respectively connected to the heat output terminal of the control device; The output ends of the heat outlet pipes are respectively connected to the heating input ends of the control device.

[0005] Preferably, the control device includes a processing control unit, a heating unit, and a supplementary heating unit; The input end of the heating unit is connected to the output end of the heat outlet pipe located in the same group of L-shaped wells, and the output end of the heating unit is connected to one input end of the lower-level unit and the supplementary heating unit. The other input terminal of the heating unit is connected to the output terminal of the heating system, and the output terminal of the heating unit is connected to the first heating input port and the second heating input port respectively; The processing and control unit is connected to the acquisition module, the heating unit, and the supplementary heating unit, respectively.

[0006] Preferably, the processing control unit is configured as follows: Based on the outlet water temperature of each L-type well in the same group and the outlet water temperature of the heating unit, a decision is generated to determine whether the L-type wells in the same group are in parallel working mode or a specific well in the group is in working mode. Based on the water outlet temperature of each L-shaped well, a decision is made on whether to continue operation or to perform recovery. Based on the heat outlet pipes of each L-shaped well and the outlet water temperature and flow rate of the heating unit, a decision on the heat replenishment mode of the heat replenishment unit and the output flow rate of the heat outlet pipes of the L-shaped well are generated. The heat replenishment mode includes either the waste heat of the heating unit or the heat replenishment system, or both combined to replenish heat. On the one hand, it maintains the stability of the heat output of the heating unit, and on the other hand, it maintains the stability of the outlet water temperature and outlet water flow at the heat output end of the heating unit, while realizing the recycling and local utilization of resources in the same group. The heat output flow rate decision is as follows: if the outlet water temperature of the heating unit and the outlet water temperature of one or more L-shaped wells in the same group are within the lower limit of the temperature threshold, then the outlet water flow rate of the corresponding L-shaped well is controlled to control the heat exchange time in the well, so that the outlet water temperature of the heating unit is within the threshold range.

[0007] Preferably, the acquisition module includes: a first temperature sensor disposed at the output end of the heat pipe of each L-shaped well, and a second temperature sensor and a flow sensor disposed at the heating output end of the control device; the first temperature sensor, the second temperature sensor, and the flow sensor are electrically connected to the processing control unit respectively.

[0008] Preferably, the heating unit and the supplementary heating unit include adjacent heating chambers and supplementary heating chambers; A heating output end is provided on one side of the heating chamber, and a heating input end is provided on the other side of the heating chamber; the heating output end is connected to the lower-level unit; the number of heating input ends matches the number of L-shaped wells in the same group, and each is connected to the output end of the heat outlet pipe of the L-shaped well; each heating input end is provided with a first flow regulating valve. A heat replenishment channel is provided between the heat replenishment cavity and the heating cavity. The heat replenishment cavity is provided with a heat replenishment input end and a heat replenishment output end. The heat replenishment input end is connected to the heat replenishment system, and the heat replenishment output end is connected to the first heat replenishment input port and the second heat replenishment input port, respectively. A control valve is provided in the heat replenishment channel, and a second flow regulating valve is provided at the first heat replenishment input port and the second heat replenishment input port, respectively. The controllers of the control valve, the first flow regulating valve, and the second flow regulating valve are respectively connected to the processing control unit.

[0009] Preferably, the processing control unit is configured to execute an adaptive control strategy, which is coupled with at least the following features: Real-time outlet water temperature (T) and flow rate (Q); Single-well historical temperature decay rate (α); Real-time heat load demand (D) of the lower-level unit; And the wellbore thermal recovery potential (P) predicted based on the formation thermal property model; The execution logic of the control strategy includes: a. Predictive control based on temperature decay rate (α) and real-time flow rate (Q): When the α of a single well exceeds the preset threshold and the real-time Q is high, the processing control unit predicts that the well will enter a period of rapid temperature decay and performs the following operations in advance: reduce the outflow rate of the well to prolong the downhole heat exchange time, and start low-frequency supplementary heating of its recovery layer to delay the formation of cold accumulation. b. Collaborative decision-making based on heat load demand (D) and heat recovery potential (P): During periods of low heating load (small D), if the system detects that a well has high heat recovery potential (large P), it will automatically switch the well to recovery mode and use the heat replenishment system and waste heat from the heating unit to provide high-intensity heat replenishment, thereby achieving energy storage during low load periods. c. Heat replenishment optimization based on flow rate (Q) and recovery potential (P): For a single well in recovery mode, the flow rate and temperature setpoint of its heat replenishment medium are jointly determined by the well's real-time outlet water temperature (T) and thermal recovery potential (P). For wells with low P values, a heat replenishment mode with low flow rate and high temperature is adopted to reduce heat loss. For wells with high P values, a heat replenishment mode with high flow rate and moderate temperature is adopted to accelerate the expansion of the thermal influence radius.

[0010] Preferably, the prediction model for the wellbore thermal recovery potential (P) takes at least the following parameters as input: The well's cumulative heat recovery during the past operating cycle; The basic temperature and thermal conductivity of the formation in which the well is located; The duration and total amount of heat replenishment for the most recent recovery mode of this well; The spacing between adjacent working wells within the same group and the intensity of their thermal interference; The processing control unit dynamically adjusts the rotation and recovery plan of each well in the well group based on the P value output by the prediction model.

[0011] Preferably, all components in the system are high-temperature and corrosion-resistant.

[0012] According to another aspect of this application, a method for simultaneous production and irrigation in an L-shaped well is provided, employing the aforementioned L-shaped well simultaneous production and irrigation system, the method comprising: S1: Bind at least two L-shaped wells into a group, and configure a control device and at least one heat replenishment system for the group of wells; the control device serves as a transfer and maintenance center, and is connected to the well pipe, lower-level unit and heat replenishment system of each L-shaped well, so as to realize the delivery of the water from the L-shaped well to the lower-level unit, and the delivery of the heat energy of the heat replenishment system to the well pipe of the corresponding L-shaped well through the control device. S2: The data acquisition module monitors the outlet water temperature and flow rate at the heating output end of the control device in real time, as well as the outlet water temperature and flow rate of each L-shaped well, and feeds the monitoring data back to the processing and control unit of the control device. S3: The processing and control unit performs the following decision-making and control operations based on the monitoring data: S31: Based on the overall outlet water temperature at the heating output end of the control device and the single well outlet water temperature of each L-shaped well, determine whether the system should be in multi-well collaborative working mode or single-well working mode. S32: For a single well that has entered recovery mode, heat is supplied to its well casing through the heating unit, and the water temperature of the well is continuously monitored. When the difference between the water temperature of the well and the water temperature of the working well is within the allowable range, the recovery mode is terminated and the system is switched back to the multi-well parallel working mode. S33: Based on the monitored temperature and flow data, dynamically adjust the opening of the flow regulating valve at the outlet of each L-shaped well and the heating mode of the heating unit to ensure stable heating output temperature and flow; the heating mode includes using the waste heat of the heating unit alone, using the heating system alone, or both in combination.

[0013] Preferably, in step S31, the working mode decision specifically includes: If the overall outlet water temperature at the heating output end of the control device is within the set output temperature range, and the outlet water temperature of each individual well is within the working temperature threshold, then the multi-well parallel working mode is adopted. If the overall outlet water temperature at the heating output end of the control device is greater than or equal to the upper limit threshold of the set output temperature, or if the outlet water temperature of a certain single well is less than the lower limit threshold of the working temperature and the outlet water temperature of the other single wells is greater than or equal to the lower limit threshold of the working temperature, then the single well with an outlet water temperature greater than or equal to the lower limit threshold of the working temperature is used as the working well and enters the single well working mode, while the single well with an outlet water temperature less than the lower limit threshold of the working temperature enters the recovery mode. If the overall outlet water temperature at the heating output end of the control device is within the lower limit threshold range of the set output temperature, and the outlet water temperature of each individual well is within the working temperature threshold range, then by adjusting the outlet water flow rate of each individual well, the heat exchange time of the working fluid in the well is extended, so that the overall outlet water temperature rises back to the set output temperature range. If the overall outlet water temperature at the heating output end of the control device is within the lower limit threshold range of the set output temperature, and the outlet water temperature of all single wells is less than the lower limit threshold of the working temperature, then the supplementary heating system is activated to supplement heat to each well pipe through the supplementary heating unit to ensure that the overall outlet water temperature is within the set output temperature range. If the overall outlet water temperature and flow rate at the heating output end of the control device are much greater than the set output temperature and flow rate, then a portion of the outlet water will be circulated to the supplementary heating unit, and the number of working wells will be adjusted to reduce the heating load.

[0014] Preferably, in step S33, the dynamic adjustment includes: A combined regulation stage based on flow adaptation and thermal recovery potential: Flow pre-regulation: Based on the predicted changes in downstream heat load demand (D), the number of working wells and their total outflow rate are adjusted in advance to ensure that the system's heating capacity smoothly tracks load changes; Temperature-flow coordinated regulation: Based on the real-time outlet water temperature (T) of each working well, the outlet water flow rate of each well is finely adjusted to ensure the overall outlet water temperature after mixing is stable; Recovery strategy matching and adjustment: For a single well entering the recovery mode, a differentiated heat replenishment flow rate and temperature are matched according to its thermal recovery potential (P) to achieve high efficiency and energy saving in the recovery process.

[0015] Compared with the prior art, the beneficial effects of this application are as follows: This application utilizes at least two L-shaped wells to form a well group. The control device dynamically regulates the working status of each well in the well group, as well as the output status of each individual well and the well group as a whole, based on the data collected by the acquisition module. The decision system enters a multi-well parallel working mode or a single-well working mode, supporting the simultaneous entry of other wells into recovery mode while some wells are extracting heat, thus avoiding "cold accumulation" of the formation around the well caused by continuous heat extraction from a single well. By rotating heat extraction and recovery among wells within the well group, it prevents the continuous decay of the formation temperature field caused by long-term extraction from a single well, maintains the overall heat exchange efficiency of the well group, and solves the pain point of traditional systems where heat supply must be interrupted during recovery. It can restore inefficient wells without stopping the overall heat supply, ensuring the continuity of heat energy supply to lower-level units and avoiding heat supply interruptions caused by well recovery.

[0016] The well casing in this application includes a heat outlet pipe, an isolation pipe, and a heat exchange pipe arranged concentrically from the inside out. A recovery layer with a heat-conducting structure is provided between the heat exchange pipe and the well wall. A first heat replenishment inlet is provided at the top of the recovery layer. A second heat replenishment inlet and a heat replenishment return inlet are provided between the isolation pipe and the heat outlet pipe. The heat replenishment medium can be directionally transported to the recovery layer and the isolation pipe. The two ends of the isolation pipe are sealed to the heat outlet pipe to form an independent heat-insulating cavity. The recovery layer is close to the well wall, and the heat of the heat replenishment medium can be directly transferred to the formation, avoiding the heat loss caused by the general heating of the traditional reinjection well. The isolation pipe maintains the cavity temperature through heat replenishment, which can prevent the high-temperature working medium in the heat outlet pipe from exchanging heat with the low-temperature environment outside, and reduce the heat loss during the transportation of the working medium. When the well is working, the recovery layer can help improve the heat exchange efficiency between the heat exchange pipe and the formation. In the recovery mode, it can provide directional heat replenishment, which can improve the utilization rate of the well casing by doing two things at once.

[0017] The control device includes a processing control unit, a heating unit, and a supplementary heating unit. The supplementary heating unit can select from three supplementary heating modes: waste heat from the heating unit, one from the supplementary heating system, or a combination of both. The processing control unit dynamically adjusts the opening of the first flow regulating valve at the outlet of each well based on the single-well temperature, flow rate, and overall heating temperature and flow rate. This controls the heat exchange time of the working fluid within the well and the status of the control valve in the supplementary heating channel. This prioritizes the use of waste heat from the heating unit for supplementary heating, activating the supplementary heating system only when insufficient, reducing external energy consumption and enabling local recycling of resources from wells within the same group. By adjusting the flow regulating valve opening (e.g., reducing the opening and extending the heat exchange time when the temperature approaches the lower threshold), combined with multi-mode supplementary heating, the overall heating output temperature can be kept stable. When the overall heating temperature / flow rate far exceeds the set value, a portion of the effluent can be circulated into the supplementary heating unit (for insulation of the isolation pipe) and the number of working wells can be reduced, flexibly matching downstream load changes and avoiding energy waste.

[0018] This avoids cold accumulation caused by continuous heating from a single well, solves the problem of inevitable interruption during restoration in existing technologies, and ensures continuous heating supply. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the overall structure of an L-shaped well-injection and irrigation system according to an embodiment of this application; Figure 2 This is a schematic diagram of the control device in an L-shaped well simultaneous production and irrigation system according to an embodiment of this application; Figure 3 This is a schematic diagram of the well casing structure in an L-shaped well production and irrigation system according to an embodiment of this application; Figure 4 This is a schematic diagram of the principle framework of an L-shaped well co-production and irrigation system in an embodiment of this application; In the attached image: 1. First L-shaped well; 2. Second L-shaped well; 3. Recovery layer; 4. Heat exchanger pipe; 5. Isolation pipe; 6. Heat outlet pipe; 7. Heat replenishment system; 8. Control device; 9. Heat supply inlet; 10. Flow regulating valve; 11. Heat replenishment outlet; 12. Heat supply outlet; 13. Heat replenishment channel; 14. Control valve; 15. Switching valve; 16. Heat replenishment inlet. Detailed Implementation

[0020] An L-shaped well-injection system, the system comprising: At least one well group, each well group including at least two L-shaped wells spaced apart, wherein well pipes are installed in the L-shaped wells; At least one heat replenishment system is provided in conjunction with the well group; A control device is provided corresponding to the well group. The heating input terminal of the control device is connected to the water outlet terminal of the L-shaped well in the same group. The heating output terminal of the control device is connected to the lower-level unit. The heat replenishment input terminal of the control device is connected to the heat replenishment system. The heat replenishment output terminal of the control device is connected to the well pipe of the L-shaped well. The data acquisition module is installed at the water outlet of each L-shaped well and the heating output of the control device to monitor the water temperature and flow rate of the L-shaped well and the control device in real time. The control device is configured to: Based on the temperature at the heating output end and the outlet water temperature of each L-shaped well, a decision is made on whether the L-shaped wells are in parallel operation mode or single well operation mode, and the well pipes of the same group of L-shaped wells are adjusted. The control status includes determining the working mode and recovery mode of the L-shaped well, selecting the recovery mode of the L-shaped well, and adjusting the outflow rate of the L-shaped well.

[0021] Furthermore, the well casing includes a heat outlet pipe and a heat exchange pipe arranged concentrically from the inside out; The heat exchange tube is installed close to the well wall and a recovery layer is provided between it and the well wall. An isolation tube is provided between the heat exchange tube and the heat outlet tube. The recovery layer is a heat-conducting structure. The outer wall of the recovery layer is in close contact with the well wall. The recovery layer is connected to the outside of the heat exchange tube. A first heat replenishment inlet is provided at the top of the recovery layer. The isolation tube is concentrically arranged with the heat outlet tube and spaced apart on the outside of the heat outlet tube. The two ends of the isolation tube are respectively sealed to the outer ends of the two ends of the heat outlet tube. A second heat replenishment inlet and a heat replenishment return outlet are provided at the sealed connection of the top ends of the isolation tube and the heat outlet tube. The first heat input port and the second heat input port are respectively connected to the heat output terminal of the control device; The output ends of the heat outlet pipes are respectively connected to the heating input ends of the control device.

[0022] It should be noted that: In this application, the second heat replenishment inlet and the heat replenishment return inlet are respectively connected to the cavity formed by the isolation tube and the heat outlet tube; while maintaining the temperature inside the isolation tube in a constant balance, the energy after the isolation tube is insulated is used elsewhere; the heat replenishment system delivers the heat preservation medium to the sealed cavity between the isolation tube and the heat outlet tube through the second heat replenishment inlet, and the medium returns to the heat replenishment system from the heat replenishment return inlet after heat exchange, realizing recycling.

[0023] In this application, the spiral plate heat exchanger or finned heat conduction structure is made of materials that are resistant to high temperature and corrosion.

[0024] Furthermore, the control device includes a processing control unit, a heating unit, and a supplementary heating unit; The input end of the heating unit is connected to the output end of the heat outlet pipe located in the same group of L-shaped wells, and the output end of the heating unit is connected to one input end of the lower-level unit and the supplementary heating unit. The other input terminal of the heating unit is connected to the output terminal of the heating system, and the output terminal of the heating unit is connected to the first heating input port and the second heating input port respectively; The processing and control unit is connected to the acquisition module, the heating unit, and the supplementary heating unit, respectively.

[0025] It should be noted that: The processing control unit described in this application is a programmable processor.

[0026] Furthermore, the processing control unit is configured to: Based on the outlet water temperature of each L-type well in the same group and the outlet water temperature of the heating unit, a decision is generated to determine whether the L-type wells in the same group are in parallel working mode or a specific well in the group is in working mode. Based on the water outlet temperature of each L-shaped well, a decision is made on whether to continue operation or to perform recovery. Based on the heat outlet pipes of each L-shaped well and the outlet water temperature and flow rate of the heating unit, a decision on the heat replenishment mode of the heat replenishment unit and the output flow rate of the heat outlet pipes of the L-shaped well are generated. The heat replenishment mode includes either the waste heat of the heating unit or the heat replenishment system, or both combined to replenish heat. On the one hand, it maintains the stability of the heat output of the heating unit, and on the other hand, it maintains the stability of the outlet water temperature and outlet water flow at the heat output end of the heating unit, while realizing the recycling and local utilization of resources in the same group. The heat output flow rate decision is as follows: if the outlet water temperature of the heating unit and the outlet water temperature of one or more L-shaped wells in the same group are within the lower limit of the temperature threshold, then the outlet water flow rate of the corresponding L-shaped well is controlled to control the heat exchange time in the well, so that the outlet water temperature of the heating unit is within the threshold range.

[0027] Furthermore, the acquisition module includes: a first temperature sensor disposed at the output end of the heat pipe of each L-shaped well, and a second temperature sensor and a flow sensor disposed at the heating output end of the control device; the first temperature sensor, the second temperature sensor, and the flow sensor are electrically connected to the processing control unit respectively.

[0028] Furthermore, the heating unit and the supplementary heating unit include adjacent heating chambers and supplementary heating chambers; A heating output end is provided on one side of the heating chamber, and a heating input end is provided on the other side of the heating chamber; the heating output end is connected to the lower-level unit; the number of heating input ends matches the number of L-shaped wells in the same group, and each is connected to the output end of the heat outlet pipe of the L-shaped well; each heating input end is provided with a first flow regulating valve. A heat replenishment channel is provided between the heat replenishment cavity and the heating cavity. The heat replenishment cavity is provided with a heat replenishment input end and a heat replenishment output end. The heat replenishment input end is connected to the heat replenishment system, and the heat replenishment output end is connected to the first heat replenishment input port and the second heat replenishment input port, respectively. A control valve is provided in the heat replenishment channel, and a second flow regulating valve is provided at the first heat replenishment input port and the second heat replenishment input port, respectively. The controllers of the control valve, the first flow regulating valve, and the second flow regulating valve are respectively connected to the processing control unit.

[0029] It should be noted that, in this application, the control valve is an electric flow regulating valve; The switching valve is a flow divider valve; In this application, all valves are automatic valves and can be controlled by a processing control unit.

[0030] Furthermore, the processing control unit is configured to execute an adaptive control strategy, which is coupled with at least the following features: Real-time outlet water temperature (T) and flow rate (Q); Single-well historical temperature decay rate (α); Real-time heat load demand (D) of the lower-level unit; And the wellbore thermal recovery potential (P) predicted based on the formation thermal property model; The execution logic of the control strategy includes: a. Predictive control based on temperature decay rate (α) and real-time flow rate (Q): When the α of a single well exceeds the preset threshold and the real-time Q is high, the processing control unit predicts that the well will enter a period of rapid temperature decay and performs the following operations in advance: reduce the outflow rate of the well to prolong the downhole heat exchange time, and start low-frequency supplementary heating of its recovery layer to delay the formation of cold accumulation. b. Collaborative decision-making based on heat load demand (D) and heat recovery potential (P): During periods of low heating load (small D), if the system detects that a well has high heat recovery potential (large P), it will automatically switch the well to recovery mode and use the heat replenishment system and waste heat from the heating unit to provide high-intensity heat replenishment, thereby achieving energy storage during low load periods. c. Heat replenishment optimization based on flow rate (Q) and recovery potential (P): For a single well in recovery mode, the flow rate and temperature setpoint of its heat replenishment medium are jointly determined by the well's real-time outlet water temperature (T) and thermal recovery potential (P). For wells with low P values, a heat replenishment mode with low flow rate and high temperature is adopted to reduce heat loss. For wells with high P values, a heat replenishment mode with high flow rate and moderate temperature is adopted to accelerate the expansion of the thermal influence radius.

[0031] Furthermore, the prediction model for the wellbore thermal recovery potential (P) requires at least the following parameters as input: The well's cumulative heat recovery during the past operating cycle; The basic temperature and thermal conductivity of the formation in which the well is located; The duration and total amount of heat replenishment for the most recent recovery mode of this well; The spacing between adjacent working wells within the same group and the intensity of their thermal interference; The processing control unit dynamically adjusts the rotation and recovery plan of each well in the well group based on the P value output by the prediction model.

[0032] Furthermore, all components in the system are high-temperature and corrosion-resistant.

[0033] According to another aspect of this application, a method for simultaneous production and irrigation in an L-shaped well is provided, employing the aforementioned L-shaped well simultaneous production and irrigation system, the method comprising: S1: Bind at least two L-shaped wells into a group, and configure a control device and at least one heat replenishment system for the group of wells; the control device serves as a transfer and maintenance center, and is connected to the well pipe, lower-level unit and heat replenishment system of each L-shaped well, so as to realize the delivery of the water from the L-shaped well to the lower-level unit, and the delivery of the heat energy of the heat replenishment system to the well pipe of the corresponding L-shaped well through the control device. S2: The data acquisition module monitors the outlet water temperature and flow rate at the heating output end of the control device in real time, as well as the outlet water temperature and flow rate of each L-shaped well, and feeds the monitoring data back to the processing and control unit of the control device. S3: The processing and control unit performs the following decision-making and control operations based on the monitoring data: S31: Based on the overall outlet water temperature at the heating output end of the control device and the single well outlet water temperature of each L-shaped well, determine whether the system should be in multi-well collaborative working mode or single-well working mode. S32: For a single well that has entered recovery mode, heat is supplied to its well casing through the heating unit, and the water temperature of the well is continuously monitored. When the difference between the water temperature of the well and the water temperature of the working well is within the allowable range, the recovery mode is terminated and the system is switched back to the multi-well parallel working mode. S33: Based on the monitored temperature and flow data, dynamically adjust the opening of the flow regulating valve at the outlet of each L-shaped well and the heating mode of the heating unit to ensure stable heating output temperature and flow; the heating mode includes using the waste heat of the heating unit alone, using the heating system alone, or both in combination.

[0034] Furthermore, the working mode decision specifically includes: If the overall outlet water temperature at the heating output end of the control device is within the set output temperature range, and the outlet water temperature of each individual well is within the working temperature threshold, then the multi-well parallel working mode is adopted. If the overall outlet water temperature at the heating output end of the control device is greater than or equal to the upper limit threshold of the set output temperature, or if the outlet water temperature of a certain single well is less than the lower limit threshold of the working temperature and the outlet water temperature of the other single wells is greater than or equal to the lower limit threshold of the working temperature, then the single well with an outlet water temperature greater than or equal to the lower limit threshold of the working temperature is used as the working well and enters the single well working mode, while the single well with an outlet water temperature less than the lower limit threshold of the working temperature enters the recovery mode. If the overall outlet water temperature at the heating output end of the control device is within the lower limit threshold range of the set output temperature, and the outlet water temperature of each individual well is within the working temperature threshold range, then by adjusting the outlet water flow rate of each individual well, the heat exchange time of the working fluid in the well is extended, so that the overall outlet water temperature rises back to the set output temperature range. If the overall outlet water temperature at the heating output end of the control device is within the lower limit threshold range of the set output temperature, and the outlet water temperature of all single wells is less than the lower limit threshold of the working temperature, then the supplementary heating system is activated to supplement heat to each well pipe through the supplementary heating unit to ensure that the overall outlet water temperature is within the set output temperature range. If the overall outlet water temperature and flow rate at the heating output end of the control device are much greater than the set output temperature and flow rate, then a portion of the outlet water will be circulated to the supplementary heating unit, and the number of working wells will be adjusted to reduce the heating load.

[0035] In step S33, the dynamic adjustment includes: A combined regulation stage based on flow adaptation and thermal recovery potential: Flow pre-regulation: Based on the predicted changes in downstream heat load demand D, the number of working wells and their total outflow rate are adjusted in advance to ensure that the system's heating capacity smoothly tracks load changes; Temperature-flow coordinated regulation: Based on the real-time outlet water temperature T of each working well, the outlet water flow rate of each well is finely adjusted to ensure the overall outlet water temperature after mixing is stable; Recovery strategy matching and adjustment: For a single well entering recovery mode, a differentiated heat replenishment flow rate and temperature are matched according to its thermal recovery potential P to achieve high efficiency and energy saving in the recovery process.

[0036] It should be noted that: In this application, throughout the entire production and irrigation process, the heat replenishment system continuously provides a heat source to the isolation layer to prevent the outlet water temperature from being affected by temperature. Whether the recovery layer is replenished depends on the working state of the corresponding well. The recovery layer adopts a heat-conducting structure. On the one hand, under the normal working mode of a single well, the heat exchange efficiency of the heat exchange tube is improved through the heat-conducting layer. On the other hand, when a single well is in recovery mode, the recovery efficiency of the well wall of the single well is improved through the structure.

[0037] When all wells in the same group enter recovery mode, the control device reports to the higher level to promptly allocate resources from nearby well groups and ensure the normal operation of the lower-level units corresponding to the recovered well group.

[0038] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0039] Example: like Figure 1 and Figure 2 As shown, this embodiment uses two L-shaped wells forming a well group as an example to illustrate an L-shaped well co-production and irrigation system described in this application. The system includes: a well group consisting of a first L-shaped well 1 and a second L-shaped well 2, a heating system 7 and a control device 8 configured corresponding to the well group; wherein L-shaped well pipes are installed in the first L-shaped well 1 and the second L-shaped well 2 respectively.

[0040] In this embodiment, the output ends of the heat outlet pipes 6 of the first L-shaped well 1 and the second L-shaped well 2 are respectively connected to the two heat supply inlets 9 of the heating unit in the control device 8 through pipes. A first flow regulating valve 10 is installed at each heat supply inlet 9. The heat supply outlet 12 of the heating unit in the control device 8 is connected to the lower-level unit, thereby forming a heat collection path. In this embodiment, the control device 8 includes a processing control unit, and a heating unit and a supplementary heating unit in two adjacent independent cavities; the output end of the supplementary heating system 7 is connected to the supplementary heating input port 16 of the supplementary heating unit in the control device 8 through a pipeline; a switching valve 15 is installed at the supplementary heating output port 11 of the supplementary heating unit in the control device 8, and the switching valve 15 is connected to the first supplementary heating input port and the second supplementary heating input port (located at the connection between the isolation pipe 5 and the top of the heat outlet pipe 6) of the first L-shaped well 1 and the second L-shaped well 2 respectively; the heating cavity and the supplementary heating cavity are connected by a supplementary heating channel 13, and a control valve 14 is installed in the supplementary heating channel 13 to control the connection between the two, thereby forming a supplementary heating path.

[0041] like Figure 3As shown, in this embodiment, the well pipe includes a heat outlet pipe 6 and a heat exchange pipe 4 arranged concentrically from the inside to the outside, as well as a recovery layer 3 between the heat exchange pipe and the well wall, and an isolation pipe 5 between the heat exchange pipe 4 and the heat outlet pipe 6. The recovery layer 3 is a spiral plate or finned heat-conducting structure that is in close contact with the well wall.

[0042] In this embodiment, the acquisition module includes a first temperature sensor and a first flow sensor respectively disposed at the output end of the heat outlet pipe 6 of the first L-shaped well 1 and the second L-shaped well 2, and a second temperature sensor and a second flow sensor disposed at the heat supply output port 12 of the control device 8.

[0043] like Figure 4 As shown, the first temperature sensor and the first flow sensor, as well as the second temperature sensor and the second flow sensor, are all connected to the processing control unit via an RS485 bus; the processing control unit is connected to the controller of the first flow regulating valve 10, the second flow regulating valve, the control valve 14, and the heating system 7, respectively.

[0044] The processing and control unit controls the operating status of the heat replenishment path and the heat collection path based on the real-time data collected by the first temperature sensor, the first flow sensor, the second temperature sensor, and the second flow sensor. Specifically: Based on the overall heating output temperature and overall output flow rate collected by the control device 8, as well as the output temperature and output flow rate of each well, the processing control unit determines that the overall temperature is within the set range and the temperature of each well is higher than the working threshold. In this case, the multi-well parallel working mode is executed. At this time, the control valve 14 of the heat replenishment channel is closed and the recovery layer does not need to be heated. The heating unit directly mixes the hot water from the two wells and delivers it downstream to ensure stable heating.

[0045] If the processing control unit determines that the overall temperature is close to the lower limit and the temperature of a single well is abnormally lower than the lower limit threshold range of the set working temperature, then the abnormal well in the two wells will enter the recovery mode and the other well will work. At this time, the heat replenishment system 7 will be started, and heat will be delivered to the abnormal well through the switching valve 15. The temperature of the abnormal well will be continuously monitored. When the temperature meets the normal working requirements, the corresponding first flow regulating valve will be opened to switch it to the multi-well parallel mode.

[0046] If the processing control unit determines that the overall temperature is abnormal and the temperature of all individual wells is below the threshold, it will execute the whole-well heating mode until the whole well recovers to the working temperature. At this time, it will promptly allocate heat to adjacent well groups to avoid heating interruption.

[0047] When the processing control unit determines that the overall temperature is close to the lower limit and the abnormal temperature of a single well is within the lower limit threshold range of the set working temperature, the heat exchange rate is controlled by the first flow regulating valve 10 to increase the outlet water temperature.

[0048] The heat replenishment includes either synergistic heat replenishment from residual heat in the same well group and heat replenishment system 7, or heat replenishment solely through heat replenishment system 7. The specific heat replenishment mode depends on the overall output temperature and flow rate of the heating unit. If both the overall output temperature and flow rate exceed the upper limit of the set output threshold range, control valve 14 (a flow valve) is opened. While ensuring the overall output temperature and flow rate remain within the set output threshold range, excess residual heat is supplied to the cavity of the heat replenishment unit, where it is combined with the heat source provided by heat replenishment system 7 and supplied to the recovery layer and isolation pipe for insulation of the water inlet and outlet and well wall recovery. If both the overall output temperature and flow rate are within the set output threshold range, heat replenishment is performed solely through heat replenishment system 7.

Claims

1. An L-shaped well-injection and irrigation system, characterized in that, The system includes: At least one well group, each well group including at least two L-shaped wells spaced apart, wherein well pipes are installed in the L-shaped wells; At least one heat replenishment system is provided in conjunction with the well group; A control device is provided corresponding to the well group. The heating input terminal of the control device is connected to the water outlet terminal of the L-shaped well in the same group. The heating output terminal of the control device is connected to the lower-level unit. The heat replenishment input terminal of the control device is connected to the heat replenishment system. The heat replenishment output terminal of the control device is connected to the well pipe of the L-shaped well. The data acquisition module is installed at the water outlet of each L-shaped well and the heating output of the control device to monitor the water temperature and flow rate of the L-shaped well and the control device in real time. The control device is configured to: Based on the temperature at the heating output end and the outlet water temperature of each L-shaped well, a decision is made on whether the L-shaped wells are in parallel operation mode or single well operation mode, and the well pipes of the same group of L-shaped wells are adjusted. The control status includes determining the working mode and recovery mode of the L-shaped well, selecting the recovery mode of the L-shaped well, and adjusting the outflow rate of the L-shaped well.

2. The L-shaped well-injection and irrigation system according to claim 1, characterized in that, The well casing includes a heat outlet pipe and a heat exchange pipe arranged concentrically from the inside to the outside; The heat exchange tube is installed close to the well wall and a recovery layer is provided between it and the well wall. An isolation tube is provided between the heat exchange tube and the heat outlet tube. The recovery layer is a heat-conducting structure. The outer wall of the recovery layer is in close contact with the well wall. The recovery layer is connected to the outside of the heat exchange tube. A first heat replenishment inlet is provided at the top of the recovery layer. The isolation tube is concentrically arranged with the heat outlet tube and spaced apart on the outside of the heat outlet tube. The two ends of the isolation tube are respectively sealed to the outer ends of the two ends of the heat outlet tube. A second heat replenishment inlet and a heat replenishment return outlet are provided at the sealed connection of the top ends of the isolation tube and the heat outlet tube. The first heat input port and the second heat input port are respectively connected to the heat output terminal of the control device; The output ends of the heat outlet pipes are respectively connected to the heating input ends of the control device.

3. The L-shaped well simultaneous production and irrigation system according to claim 2, characterized in that, The control device includes a processing control unit, a heating unit, and a supplementary heating unit; The input end of the heating unit is connected to the output end of the heat outlet pipe located in the same group of L-shaped wells, and the output end of the heating unit is connected to one input end of the lower-level unit and the supplementary heating unit. The other input terminal of the heating unit is connected to the output terminal of the heating system, and the output terminal of the heating unit is connected to the first heating input port and the second heating input port respectively; The processing and control unit is connected to the acquisition module, the heating unit, and the supplementary heating unit, respectively.

4. The L-shaped well-injection and irrigation system according to claim 3, characterized in that, The processing control unit is configured to: Based on the outlet water temperature of each L-type well in the same group and the outlet water temperature of the heating unit, a decision is generated to determine whether the L-type wells in the same group are in parallel working mode or a specific well in one of them is in working mode. Based on the water outlet temperature of each L-shaped well, a decision is made on whether to continue operation or to perform recovery. Based on the heat outlet pipes of each L-shaped well and the outlet water temperature and flow rate of the heating unit, a decision on the heat replenishment mode of the heat replenishment unit and the output flow rate of the heat outlet pipes of the L-shaped well are generated. The heat replenishment mode includes either the waste heat of the heating unit or the heat replenishment system, or both combined to replenish heat. On the one hand, it maintains the stability of the heat output of the heating unit, and on the other hand, it maintains the stability of the outlet water temperature and outlet water flow at the heat output end of the heating unit, while realizing the recycling and local utilization of resources in the same group. The heat output flow rate decision is as follows: if the outlet water temperature of the heating unit and the outlet water temperature of one or more L-shaped wells in the same group are within the lower limit of the temperature threshold, then the outlet water flow rate of the corresponding L-shaped well is controlled to control the heat exchange time in the well, so that the outlet water temperature of the heating unit is within the threshold range.

5. The L-shaped well simultaneous production and irrigation system according to claim 3, characterized in that, The heating unit and the supplementary heating unit include adjacent heating chambers and supplementary heating chambers; A heating output end is provided on one side of the heating chamber, and a heating input end is provided on the other side of the heating chamber; the heating output end is connected to the lower-level unit; the number of heating input ends matches the number of L-shaped wells in the same group, and each is connected to the output end of the heat outlet pipe of the L-shaped well; each heating input end is provided with a first flow regulating valve. A heat replenishment channel is provided between the heat replenishment cavity and the heating cavity. The heat replenishment cavity is provided with a heat replenishment input end and a heat replenishment output end. The heat replenishment input end is connected to the heat replenishment system, and the heat replenishment output end is connected to the first heat replenishment input port and the second heat replenishment input port, respectively. A control valve is provided in the heat replenishment channel, and a second flow regulating valve is provided at the first heat replenishment input port and the second heat replenishment input port, respectively. The controllers of the control valve, the first flow regulating valve, and the second flow regulating valve are respectively connected to the processing control unit.

6. The L-shaped well-injection and irrigation system according to claim 3, characterized in that, The processing control unit is configured to execute an adaptive control strategy, which is coupled with at least the following features: Real-time outlet water temperature T and flow rate Q; The rate of temperature decay α in the history of a single well; The real-time heat load demand D of the lower-level unit; And the wellbore thermal recovery potential P predicted based on the formation thermal property model; The execution logic of the control strategy includes: a. Predictive control based on temperature decay rate α and real-time flow rate Q: When α of a certain well exceeds the preset threshold and its real-time Q is high, the processing control unit predicts that the well will enter a period of rapid temperature decay and performs the following operations in advance: reduce the outflow rate of the well to prolong the downhole heat exchange time, and start low-frequency supplementary heating of its recovery layer to delay the formation of cold accumulation. b. Based on the coordinated decision of heat load demand D and heat recovery potential P: During periods of low heating load, i.e., when D is small, if the system detects that a well has a high heat recovery potential, i.e., when P is large, the well will be automatically switched to recovery mode, and the heat replenishment system and the waste heat of the heating unit will be used to provide high-intensity heat replenishment to achieve energy storage during low load periods. c. Heat replenishment optimization based on flow rate Q and recovery potential P: For a single well in recovery mode, the flow rate and temperature setpoint of its heat replenishment medium are jointly determined by the real-time outlet water temperature T and the heat recovery potential P of the well. For wells with low P value, a heat replenishment mode with low flow rate and high temperature is adopted to reduce heat loss. For wells with high P value, a heat replenishment mode with high flow rate and moderate temperature is adopted to accelerate the expansion of the thermal influence radius.

7. The L-shaped well-injection and irrigation system according to claim 6, characterized in that, The prediction model for the wellbore thermal recovery potential P requires at least the following parameters: The well's cumulative heat recovery during the past operating cycle; The basic temperature and thermal conductivity of the formation in which the well is located; The duration and total amount of heat replenishment for the most recent recovery mode of this well; The spacing between adjacent working wells within the same group and the intensity of their thermal interference; The processing control unit dynamically adjusts the rotation and recovery plan of each well in the well group based on the P value output by the prediction model.

8. A method for simultaneous production and irrigation in an L-shaped well, characterized in that, The method of using an L-shaped well with simultaneous production and irrigation system as described in any one of claims 1 to 7 includes: S1: Bind at least two L-shaped wells into a group, and configure a control device and at least one heat replenishment system for the group of wells; the control device serves as a transfer and maintenance center, and is connected to the well pipe, lower-level unit and heat replenishment system of each L-shaped well, so as to realize the delivery of the water from the L-shaped well to the lower-level unit, and the delivery of the heat energy of the heat replenishment system to the well pipe of the corresponding L-shaped well through the control device. S2: The data acquisition module monitors the outlet water temperature and flow rate at the heating output end of the control device in real time, as well as the outlet water temperature and flow rate of each L-shaped well, and feeds the monitoring data back to the processing and control unit of the control device. S3: The processing and control unit performs the following decision-making and control operations based on the monitoring data: S31: Based on the overall outlet water temperature at the heating output end of the control device and the single well outlet water temperature of each L-shaped well, determine whether the system should be in multi-well collaborative working mode or single-well working mode. S32: For a single well that has entered recovery mode, heat is supplied to its well casing through the heating unit, and the water temperature of the well is continuously monitored. When the difference between the water temperature of the well and the water temperature of the working well is within the allowable range, the recovery mode is terminated and the system is switched back to the multi-well parallel working mode. S33: Based on the monitored temperature and flow data, dynamically adjust the opening of the flow regulating valve at the outlet of each L-shaped well and the heating mode of the heating unit to ensure stable heating output temperature and flow; the heating mode includes using the waste heat of the heating unit alone, using the heating system alone, or both in combination.

9. The method for simultaneous production and irrigation in an L-shaped well according to claim 8, characterized in that, In step S31, the working mode decision specifically includes: If the overall outlet water temperature at the heating output end of the control device is within the set output temperature range, and the outlet water temperature of each individual well is within the working temperature threshold, then the multi-well parallel working mode is adopted. If the overall outlet water temperature at the heating output end of the control device is greater than or equal to the upper limit threshold of the set output temperature, or if the outlet water temperature of a certain single well is less than the lower limit threshold of the working temperature and the outlet water temperature of the other single wells is greater than or equal to the lower limit threshold of the working temperature, then the single well with an outlet water temperature greater than or equal to the lower limit threshold of the working temperature is used as the working well and enters the single well working mode, while the single well with an outlet water temperature less than the lower limit threshold of the working temperature enters the recovery mode. If the overall outlet water temperature at the heating output end of the control device is within the lower limit threshold range of the set output temperature, and the outlet water temperature of each individual well is within the working temperature threshold range, then by adjusting the outlet water flow rate of each individual well, the heat exchange time of the working fluid in the well is extended, so that the overall outlet water temperature rises back to the set output temperature range. If the overall outlet water temperature at the heating output end of the control device is within the lower limit threshold range of the set output temperature, and the outlet water temperature of all single wells is less than the lower limit threshold of the working temperature, then the supplementary heating system is activated to supplement heat to each well pipe through the supplementary heating unit to ensure that the overall outlet water temperature is within the set output temperature range. If the overall outlet water temperature and flow rate at the heating output end of the control device are much greater than the set output temperature and flow rate, then a portion of the outlet water will be circulated to the supplementary heating unit, and the number of working wells will be adjusted to reduce the heating load.

10. The method for simultaneous production and irrigation in an L-shaped well according to claim 9, characterized in that, In step S33, the dynamic adjustment includes: A combined regulation stage based on flow adaptation and thermal recovery potential: Flow pre-regulation: Based on the predicted changes in downstream heat load demand D, the number of working wells and their total outflow rate are adjusted in advance to ensure that the system's heating capacity smoothly tracks load changes; Temperature-flow coordinated regulation: Based on the real-time outlet water temperature T of each working well, the outlet water flow rate of each well is finely adjusted to ensure the overall outlet water temperature after mixing is stable; Recovery strategy matching and adjustment: For a single well entering recovery mode, a differentiated heat replenishment flow rate and temperature are matched according to its thermal recovery potential P to achieve high efficiency and energy saving in the recovery process.

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