Long-time multi-point underground temperature measuring system and method

Abstract

The invention relates to a long-time multi-point underground temperature measuring system and a long-time multi-point underground temperature measuring method. The system comprises an underground measurement unit, a lifting unit, a data acquisition and processing unit and an Internet of Things unit, the underground measuring unit is composed of a plurality of underground instruments, each underground instrument is hung on a single-core cable through an instrument bus, and the single-core cable simultaneously realizes power supply and uplink transmission of coded temperature data. The lifting unit completes lowering and lifting of the single-core cable and the underground measuring unit through a variable-frequency winch control system; the data acquisition and processing unit decodes the uploaded data to obtain the temperature of each measuring point, associatively stores the temperature with the acquisition time and the well depth, and displays the well temperature change on a local interface in real time; the Internet of Things unit sends the temperature, time and well depth data to a remote server or a cloud platform through a mobile communication network to realize remote query and centralized management of underground temperature data; according to the invention, long-time monitoring of multi-depth underground temperature is realized on a single cable, the anti-interference capability is strong, and the system is suitable for oil and gas wells, geothermal wells and other scenes.

Description

Technical Field

[0001] This invention belongs to the field of downhole exploration technology, specifically relating to a long-term, multi-point downhole temperature measurement system and method. Background Technology

[0002] In downhole exploration and development fields such as oil, geothermal energy, and underground space, long-term, multi-point gradient monitoring of downhole temperature is of great significance. The relevant data directly relates to reservoir evaluation, production capacity analysis, casing integrity assessment, and wellbore integrity and safe operation. Continuous observation of temperature changes at different depths in the wellbore allows for more detailed analysis of fluid migration, the location of thermal breakthrough fronts, and the impact of downhole operations on the formation, providing fundamental data support for development scheme optimization and safety decisions.

[0003] Currently, many well sites still rely heavily on manual downhole temperature measurement or intermittent logging operations to obtain downhole temperature data. These methods are labor-intensive, costly, and have long measurement cycles, making it difficult to reflect dynamic changes in downhole temperature in a timely manner. Furthermore, errors can easily be introduced due to manual operation and repeated instrument deployment, making it difficult to guarantee the continuity and reliability of the data, and hindering long-term trend analysis and anomaly identification.

[0004] Existing downhole temperature measurement systems typically employ multi-core or multi-channel cables for power supply and signal transmission, resulting in low system integration, complex wiring, and high overall costs. In the complex electromagnetic environment of downhole systems, cables are susceptible to electromagnetic interference from frequency converters, motors, and other sources when transmitting power and data signals, leading to signal distortion or loss. Furthermore, some traditional systems only store and display data locally on the surface, lacking the remote transmission and centralized management capabilities integrated with IoT platforms. This makes it difficult for users to obtain and flexibly access downhole temperature data in a timely manner, limiting the application value of well temperature information in production management and intelligent analysis.

[0005] Therefore, there is an urgent need for a long-term, multi-point downhole temperature measurement system with a relatively simple structure, strong anti-interference ability, capable of multi-point temperature acquisition on a single cable, supporting long-term continuous monitoring, and reliably transmitting data to a remote platform for centralized storage and visual management, so as to improve the automation level and data utilization efficiency of downhole temperature monitoring. Summary of the Invention

[0006] This invention provides a long-term, multi-point downhole temperature measurement system and method to solve problems in the prior art such as limited downhole temperature monitoring points, discontinuous measurement, complex cable structure, and insufficient anti-interference and long-distance transmission capabilities.

[0007] To achieve the above objectives, the technical solution of the present invention is as follows: In a first aspect, the present invention provides a long-term, multi-point downhole temperature measurement system, comprising: A downhole measurement unit is used to be deployed inside the wellbore and to collect temperature parameters at multiple depths in the formation. The downhole measurement unit includes multiple downhole instruments connected by a single-core cable. Each downhole instrument includes a temperature sensor, a signal conditioning circuit, an analog-to-digital converter, a main processor, and a bus drive circuit. The multiple downhole instruments are interconnected through an instrument bus located inside the downhole measurement unit. The surface hoisting unit includes a surface winch and its drive control system, used to carry and lower or raise the downhole measurement unit to a predetermined layer via the single-core cable; The ground data acquisition and processing unit is electrically connected to the downhole measurement unit via the single-core cable. It is used to supply power to the downhole measurement unit and interact with the downhole measurement unit. The ground data acquisition and processing unit includes a data decoding unit and a data storage unit. The data decoding unit is used to decode the coded temperature data uploaded via the single-core cable to obtain temperature information. The data storage unit is used to store the temperature information and the time and depth information corresponding to the temperature information. The Internet of Things (IoT) unit is connected to the ground data acquisition and processing unit and is used to send the temperature information to a remote server or cloud platform via a mobile communication network. The single-core cable is used to supply power to the downhole measurement unit and to transmit the coded temperature data.

[0008] Furthermore, the instrument bus is a TPS bus, which simultaneously provides power to multiple downhole instruments and carries the temperature data of each downhole instrument via the single-core cable.

[0009] Furthermore, the main processor is configured to perform Manchester encoding on the acquired temperature data and couple the Manchester-encoded data to the single-core cable for transmission via the bus driver circuit; the data decoding unit includes a Manchester decoding chip for decoding the Manchester-encoded data transmitted via the single-core cable.

[0010] Furthermore, the ground lifting unit includes a variable frequency winch control system, which includes a noise reduction system, a main control chip, a detection and control module, and an alarm module. The noise reduction system is used to suppress electromagnetic interference generated during the operation of the variable frequency drive unit and the motor. The main control chip is an industrial-grade microcontroller. The detection and control module detects and controls the frequency converter, motor, depth measurement device, and tension sensor through bus and CAN communication. The alarm module is used to output a switch alarm signal to trigger external safety devices when the depth or tension exceeds a preset upper limit.

[0011] Furthermore, the data storage unit includes a NAND flash memory and a ferroelectric memory, wherein the NAND flash memory is used to store well temperature data, time information, and depth information. The storage capacity of the data storage unit is configured according to the fastest sampling frequency set by the user. The ground data acquisition and processing unit is configured to allow the user to set the sampling time interval for temperature data and the time interval for sending data to the Internet of Things unit.

[0012] Furthermore, the IoT unit employs an industrial-grade 4G or GPRS communication module and an external high-gain wall-mounted antenna to stably transmit the temperature information to the remote server or cloud platform in a wide temperature environment.

[0013] Furthermore, the measurement system also includes a wellhead device, which includes a cable sealing flange, a water injection port and a water injection valve, a pressure relief port and a pressure relief valve. The cable sealing flange adopts a double-cone sealing structure to achieve wellhead sealing when the single-core cable passes through the wellhead. The pressure relief port and the pressure relief valve are used to release wellhead pressure before and after lowering or raising the downhole measurement unit. The water injection port and the water injection valve are used to inject water into the well during downhole measurement.

[0014] Secondly, the present invention provides a method for long-term, multi-point downhole temperature measurement, comprising: Downhole measurement unit deployment: The downhole measurement unit, which includes multiple downhole instruments, is connected to the surface data acquisition and processing unit via a single-core cable. The multiple downhole instruments are interconnected through an instrument bus located inside the downhole measurement unit and communicate with the surface data acquisition and processing unit via the single-core cable. The downhole measurement unit is lowered to the target layer inside the wellbore using a surface hoisting unit. Temperature acquisition and encoding: Temperature signals at their respective locations are acquired by the temperature sensors of each downhole instrument. These signals are then converted into digital data by a signal conditioning circuit and an analog-to-digital converter. The main processor of the downhole instrument packages and encodes the digital data according to a bus protocol, and the encoded temperature data is coupled to the single-core cable and transmitted to the surface via a bus drive circuit. Ground decoding and storage: The ground data acquisition and processing unit supplies power to the downhole measurement unit through the single-core cable and receives the coded temperature data. The data decoding unit decodes the coded temperature data to obtain the temperature information of each measuring point, and stores the temperature information and the corresponding time and depth information in the data storage unit. Remote transmission and display: The IoT unit receives the temperature information and packages it to send to a remote server or cloud platform via a mobile communication network for remote terminals to query, display and manage.

[0015] Furthermore, before the deployment step of the downhole measurement unit, the wellhead device operation step is also included: opening the pressure relief valve to release the wellhead pressure, unscrewing the cable sealing flange, passing the single-core cable connecting the downhole measurement unit through the center hole of the cable sealing flange and opening the wellhead valve, lowering the downhole measurement unit to the target layer and then tightening the cable sealing flange and closing the pressure relief valve; during the measurement process, water is injected into the well through the water injection port and water injection valve.

[0016] Furthermore, in the remote transmission and display step, the remote server generates a temperature gradient curve based on the received temperature information and corresponding depth information, and stores the logging data in a database for long-term archiving and analysis.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: The long-term multi-point downhole temperature measurement system provided in this invention uses a single-core cable to simultaneously power and transmit data to the downhole measurement unit. Compared to multi-core or multi-channel cable solutions, this significantly simplifies the downhole cable structure, improves system reliability, and reduces deployment difficulty and cost. Multiple downhole instruments are connected internally via an instrument bus, enabling each instrument to independently acquire and address data, achieving multi-point measurement without increasing the number of cables passing through the wellhead. The surface data acquisition and processing unit integrates data decoding, storage, and local display functions, and allows users to set sampling and upload intervals according to their needs, resulting in strong system adaptability. The accompanying wellhead device uses a dedicated cable sealing flange and pressure relief / water injection structure, ensuring reliable sealing when the single-core cable passes through the wellhead and facilitating wellhead pressure release and water injection operations, thus improving long-term operational safety. Overall, the system of this invention has a compact structure and high integration, making it suitable for widespread application in downhole scenarios such as oil and gas wells and geothermal wells.

[0018] The long-term, multi-point downhole temperature measurement method provided in this invention connects multiple downhole instruments to the same single-core cable and instrument bus, enabling temperature acquisition at multiple depths within the wellbore during a single deployment. This achieves continuous, long-term monitoring at multiple points, avoiding the operational risks and data discontinuity issues associated with repeatedly deploying and retrieving temperature measurement tools. The method digitizes the downhole temperature signals and encodes them downhole. Through surface data decoding and storage, the temperature information is linked and archived with the acquisition time and well depth information, providing complete time and spatial axes for the well temperature data. This facilitates temperature gradient analysis and long-term trend assessment. Furthermore, the method incorporates an Internet of Things (IoT) unit to automatically upload the collected multi-point downhole temperature data to a remote server or cloud platform at set intervals, reducing manual transcription and compilation workload and improving data utilization efficiency and remote maintenance capabilities.

[0019] Of course, implementing the various technical solutions of this invention does not necessarily require achieving all of the advantages described above at the same time. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other embodiments can be obtained from these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the downhole system configuration according to an embodiment of the present invention; Figure 2 This is a block diagram of the downhole measurement unit structure according to an embodiment of the present invention; Figure 3 This is a flowchart of ground unit data processing according to an embodiment of the present invention; Figure 4 This is a schematic diagram of the wellhead device according to an embodiment of the present invention.

[0022] In the diagram, 100 is the downhole measurement unit, 200 is the surface lifting unit, 300 is the surface data acquisition and processing unit, 400 is the Internet of Things unit, 500 is the wellhead device, and 110 is the downhole instrument. Detailed Implementation

[0023] The present invention will now be described in further detail with reference to specific embodiments and accompanying drawings. Similar elements in different embodiments are referred to by associated similar element reference numerals. In the following embodiments, many details are described to facilitate a better understanding of this application. However, those skilled in the art will readily recognize that some features may be omitted in different situations, or may be replaced by other elements, materials, or methods. In some cases, certain operations related to this application are not shown or described in the specification. This is to avoid obscuring the core parts of this application with excessive description. For those skilled in the art, detailed description of these related operations is not necessary; they can fully understand the related operations based on the description in the specification and general technical knowledge in the art.

[0024] Furthermore, the features, operations, or characteristics described in the specification can be combined in any suitable manner to form various embodiments. At the same time, the steps or actions in the method description can be rearranged or adjusted in a manner obvious to those skilled in the art. Therefore, the various orders in the specification and drawings are only for the clear description of a particular embodiment and do not imply a necessary order, unless otherwise stated that a particular order must be followed.

[0025] Example 1 As Figure 1 shown, a long-term multi-point downhole temperature measurement system provided in this embodiment includes a downhole measurement unit 100, a surface lifting unit 200, a surface data acquisition and processing unit 300, and an Internet of Things unit 400. Preferably, the system further includes a wellhead device 500 that is matched with a single-core cable for sealing when the cable passes through the wellhead and wellhead pressure management. Each unit forms a complete measurement link through a single-core cable and signal connection to achieve long-term continuous monitoring of multi-point downhole temperatures and remote data transmission.

[0026] In this embodiment, the downhole measurement unit 100 is arranged in the target wellbore, electrically connected to the surface data acquisition and processing unit 300 through a single-core cable, and the lowering and lifting control is performed by the surface lifting unit 200. The Internet of Things unit 400 communicates with the surface data acquisition and processing unit 300 and is used to upload the measured multi-point downhole temperature data to a remote server or cloud platform.

[0027] In the specific implementation manner of the downhole measurement unit 100, as Figure 2 shown, the downhole measurement unit 100 is composed of multiple downhole instruments 110 (such as T1, T2, T3,..., Tn, etc.) arranged axially in sequence. Each downhole instrument 110 is electrically connected to the single-core cable through an instrument bus. Each downhole instrument 110 internally includes a temperature sensor, a signal conditioning circuit, an analog-to-digital converter ADC, a main processor, and a bus driver circuit. The temperature sensor is preferably a PT1000 platinum resistance sensor for collecting the downhole temperature signal at the corresponding depth position, with high temperature measurement accuracy and long-term stability. The signal conditioning circuit converts the resistance signal output by the temperature sensor into a stable voltage signal suitable for analog-to-digital conversion and filters out interference components. The analog-to-digital converter converts the analog voltage signal into digital temperature data. The main processor preferably uses an industrial-grade single-chip microcomputer for periodically collecting temperature data, preprocessing the collected data, and packing and encoding the data according to the bus protocol; the bus driver circuit converts the digital signal output by the main processor into an electrical signal that meets the bus transmission requirements and couples it to the single-core cable.

[0028] In this embodiment, multiple downhole instruments 110 are connected in parallel to the same single-core cable through an instrument bus. Preferably, the instrument bus adopts a TPS bus structure, and each downhole instrument 110 has an independent address identifier, and addressing and data polling are achieved through the bus protocol. The single-core cable simultaneously provides power for the downhole measurement unit 100 and carries the encoded temperature data sent by each downhole instrument 110, realizing a multi-point measurement structure of a single-core cable combined with a bus multi-node, reducing the number of downhole cables and the number of cable penetration holes at the wellhead, and facilitating construction and long-term operation.

[0029] The specific implementation of the surface hoisting unit 200 is as follows. The surface hoisting unit 200 mainly includes a winch mechanical body, a frequency converter drive unit, a high-precision depth measuring device, and a frequency converter winch control system. The winch mechanical body is used to wind and release the single-core cable, thereby driving the downhole measuring unit 100 to move up and down along the wellbore. The frequency converter drive unit converts the fixed power frequency power supply into a frequency-adjustable AC power supply to regulate the speed and output torque of the drive motor, making the lowering and hoisting process of the downhole measuring unit smooth and controllable.

[0030] The main control chip of the variable frequency winch control system is preferably an industrial-grade microcontroller, used to achieve stable control of the frequency converter and winch actuator under wide temperature and vibration environments. The system interacts with the frequency converter, depth measurement device, and tension sensor via bus and CAN communication. On one hand, it sends start / stop and speed control commands to the frequency converter; on the other hand, it acquires well depth and cable tension signals in real time. To reduce the impact of electromagnetic interference generated during the operation of the frequency converter and motor on the single-core cable signal and downhole precision measuring instruments, this embodiment incorporates a noise suppression module in the variable frequency winch control system. Electromagnetic interference is suppressed through filtering, shielding, and grounding measures, improving the overall anti-interference capability of the system.

[0031] In terms of safety control, the ground hoisting unit 200 supports threshold settings for depth and tension, as well as alarm interlocking functions. Users can preset upper limits for depth and tension. When the actual depth or tension reaches the preset value, the system outputs a switch alarm signal to trigger external safety devices to implement protective actions such as deceleration or stopping. Furthermore, when the system detects a depth of 0 meters, it automatically executes zero-position protection, stopping the winch operation to prevent damage to equipment and the wellhead due to misoperation. The system only allows the winch to be restarted after the user confirms the reset via the control panel. Through the above monitoring and interlocking mechanisms, the safety and reliability of the system's lowering and hoisting processes are improved.

[0032] The specific implementation of the ground data acquisition and processing unit 300 is as follows: Figure 3 As shown. This unit uses an industrial-grade embedded computer or a dedicated data acquisition and control board as its core, integrating modules such as a data decoding unit, a depth acquisition unit, and a data storage unit. The front end of the data decoding unit is connected to a single-core cable, receiving coded signals from the downhole measurement unit 100 through isolation and filtering circuits. A dedicated Manchester decoding chip decodes the Manchester-encoded data stream to recover the digital temperature data and address information of each downhole instrument 110. The decoded valid data is encapsulated into standard data frames. One path is provided to the local display interface for plotting temperature versus time and depth curves, while the other path is written to the data storage unit. Simultaneously, it can be transmitted to the IoT unit 400 via a serial port or bus interface.

[0033] The depth acquisition unit is used to acquire the pulse or coded signals output by the winch depth measurement device, and to protect, filter, and shape the signals. By counting the depth pulses and combining this with the winch drum diameter and cable winding condition, the real-time depth information of the downhole measurement unit 100 in the wellbore can be obtained. The digital gate circuits in the depth acquisition unit are used to shape the input signal to obtain a count signal with clear amplitude and edges, thereby improving the accuracy of depth measurement.

[0034] The data storage unit is used for long-term storage of well temperature data, acquisition time information, and corresponding depth information. In this embodiment, the data storage unit includes a NAND flash memory and a ferroelectric memory. The NAND flash memory is used to store a large amount of measurement data and time and depth information, while the ferroelectric memory can be used to store key configuration parameters and important status information. The data storage capacity can be configured according to the sampling time interval set by the user to meet the storage requirements under long-term, intensive sampling conditions. The ground data acquisition and processing unit 300 provides a human-machine interface, allowing users to set the temperature sampling interval, data storage strategy, and the time interval for uploading data to the Internet of Things unit 400.

[0035] The specific implementation of the IoT unit 400 is as follows. The IoT unit 400 communicates with the ground data acquisition and processing unit 300, using an industrial-grade 4G or GPRS communication module as the core communication device. This module has wide operating temperature capabilities and can be connected to an external high-gain wall-mounted antenna to improve signal coverage and transmission stability. The IoT unit 400 packages the data from the data acquisition and processing unit 300 according to a preset strategy and, according to a set period or triggering conditions, sends the temperature and corresponding time and depth information of multiple points downhole to a remote server or cloud platform via a mobile communication network. The remote side can deploy data receiving and display software on an industrial control computer or server to store, visualize, and generate reports of the received logging data. Multiple master station access can be configured as needed to achieve cross-regional and cross-departmental data sharing and centralized management.

[0036] The specific implementation of the wellhead device 500 is as follows: Figure 4As shown, the wellhead device 500 is primarily a three-way assembly with a dual-valve structure. The upper part features a cable sealing flange with a double-cone sealing structure to ensure reliable sealing when a single-core cable passes through the wellhead. The three-way assembly has a water injection port and a water injection valve on the side, and a pressure relief port and a pressure relief valve at the bottom. In use, before lowering the device into the well, the wellhead pressure is first released through the pressure relief valve. After confirming the pressure has dropped to a safe range, the cable sealing flange is loosened, and the single-core cable connecting the downhole measurement unit 100 is passed through the center hole of the flange. The upper and lower valves are then opened sequentially, and the surface winch is started to lower the downhole measurement unit 100 to the predetermined layer. After the instrument is in place, the cable sealing flange is tightened to the specified torque, and the pressure relief valve is closed. If necessary, water is injected into the well through the water injection port and water injection valve. After completion, the water injection valve is closed. This wellhead device 500 ensures sealing and safety during cable entry and exit from the wellhead, while also facilitating pressure release and water injection operations, making it suitable for long-term online monitoring.

[0037] In summary, the long-term multi-point downhole temperature measurement system described in this embodiment, through the coordinated work of the downhole measurement unit 100, the surface lifting unit 200, the surface data acquisition and processing unit 300, the Internet of Things unit 400, and the wellhead device 500, achieves long-term continuous monitoring of downhole temperature at multiple points based on a single cable, and supports local storage and remote transmission of data. The overall structure and function correspond to the system solution in the claims.

[0038] Example 2 This embodiment provides a long-term, multi-point downhole temperature measurement method, which can be implemented based on the long-term, multi-point downhole temperature measurement system described in Embodiment 1. This method is applicable to wellbore environments such as oil and gas wells and geothermal wells, enabling long-term continuous monitoring of downhole temperatures at multiple depths. Specifically, it includes the following steps: Step 1: Deployment and System Initialization of the Downhole Measurement Unit: First, preparatory operations are performed at the wellhead. The operator opens the wellhead pressure relief valve and observes the pressure gauge until the wellhead pressure drops to a safe range. The cable sealing flange is then loosened, and the single-core cable connecting to the downhole measurement unit is passed through the center hole of the cable sealing flange and electrically connected to the surface hoisting unit and the surface data acquisition and processing unit. Subsequently, the upper and lower valves at the wellhead are opened sequentially, and the variable frequency winch control system is started. The downhole measurement unit is smoothly lowered down the wellbore to the predetermined target layer. During the lowering process, the variable frequency winch control system collects depth and tension signals in real time through the depth measurement device and tension sensor. When the depth or tension approaches the preset upper limit, an alarm is issued or external safety devices are activated to slow down or stop the process, ensuring the lowering process is safe and controllable. After the downhole measurement unit reaches the target depth range and is stably suspended, the cable sealing flange is tightened to the specified torque, the pressure relief valve is closed, and water is injected through the water injection port if necessary, completing the system initialization.

[0039] Step Two: Temperature Acquisition and Encoding: After the downhole measurement unit is stably positioned, multiple downhole instruments begin operating according to a preset sampling cycle under the unified scheduling of their internal main processors. The temperature sensor within each downhole instrument acquires the temperature signal at its depth. The signal conditioning circuit converts the resistance signal output by the temperature sensor into a stable analog voltage signal, which is then converted into digital temperature data by the analog-to-digital converter. The main processor packages the acquired digital temperature data according to the instrument bus protocol and the address information of each downhole instrument, encodes the data frames using Manchester encoding, and loads them onto a single-core cable via the bus driver circuit for transmission to the surface. During this process, the single-core cable is powered by the surface data acquisition and processing unit and simultaneously carries the encoded temperature data uploaded by each downhole instrument, enabling periodic acquisition and serial transmission of temperatures from multiple measurement points.

[0040] Step 3: Surface Decoding and Storage: The surface data acquisition and processing unit is operational throughout the monitoring process, receiving coded signals from the single-core cable via the front-end interface. The data decoding unit isolates, filters, and shapes the input signal, then uses a Manchester decoding chip to decode the signal, recovering the digital temperature data and corresponding address information uploaded by each downhole instrument. The depth acquisition unit synchronously receives depth signals from the depth measurement device, protects, filters, and shapes the depth signals, and obtains the current well depth information of the downhole measurement unit through counting and conversion. The data storage unit associates the decoded temperature data of each measuring point with the corresponding acquisition time and well depth information, and stores it in memory to form a measurement record of downhole temperature changes over time and depth. The surface data acquisition and processing unit can also display multi-point temperature and depth information in real time on a local display interface in the form of curves or lists, and provides a parameter setting interface for setting operating parameters such as temperature sampling interval, data retention period, and upload interval.

[0041] Step 4: Remote Transmission and Display: The IoT unit, according to a pre-set upload strategy, reads temperature, time, and depth data within a specific time window from the ground data acquisition and processing unit. After packaging the data, it transmits it to a remote server or cloud platform via an industrial-grade 4G mobile communication module or a general packet radio service module. The IoT unit can select an appropriate upload interval based on the sampling frequency and data volume, ensuring data timeliness while reducing communication bandwidth usage. The remote server parses, stores, and manages the received data, generating temperature gradient curves and historical temperature curves according to well number, measurement frequency, and time interval. These curves are available for viewing and analysis by management personnel on industrial computers, large-screen display terminals, or web interfaces. By configuring alarm rules, when well temperature changes at certain depths exceed preset thresholds, the cloud platform can push alarm information to relevant personnel to assist in on-site operational decision-making.

[0042] Step 5: Long-Term Operation Monitoring and Downhole Measurement Unit Retrieval: During long-term system operation, the downhole measurement unit can remain suspended at the target depth, continuously completing temperature acquisition, surface decoding and storage, and remote transmission and display according to the procedures described in Steps 2 to 4. Depending on operational requirements, operators can use the surface hoisting unit to appropriately raise or lower the downhole measurement unit to obtain temperature distribution data for different depth ranges. When it is necessary to terminate the measurement or perform maintenance, data upload from the IoT unit is stopped. The variable frequency winch control system controls the winch to smoothly raise the downhole measurement unit to the wellhead, closes the water injection valve and wellhead valve, opens the pressure relief valve to release remaining pressure, and finally removes the cable sealing flange and retrieves the downhole measurement unit. This completes one full long-term, multi-point downhole temperature measurement cycle.

[0043] Through the above steps, the long-term multi-point downhole temperature measurement method provided in this embodiment achieves long-term continuous monitoring of downhole temperatures at multiple depths based on a single-core cable and instrument bus structure. It combines a surface data acquisition and processing unit and an Internet of Things (IoT) unit to complete data decoding, storage, and remote transmission. The method steps are consistent with the downhole measurement unit deployment steps, temperature acquisition and encoding steps, surface decoding and storage steps, and remote transmission and display steps defined in the claims. The above description is merely a preferred embodiment of this disclosure and an explanation of the technical principles used. Those skilled in the art should understand that the scope of this disclosure is not limited to the technical solutions formed by specific combinations of the above-mentioned technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-mentioned technical features or their equivalent features without departing from the above-mentioned disclosed concept. For example, technical solutions formed by substituting the above-mentioned features with (but not limited to) technical features with similar functions disclosed in this disclosure.

[0044] Furthermore, while the operations are described in a specific order, this should not be construed as requiring these operations to be performed in the specific order shown or in a sequential order. In certain environments, multitasking and parallel processing may be advantageous. Similarly, while several specific implementation details are included in the above discussion, these should not be construed as limiting the scope of this disclosure. Certain features described in the context of individual embodiments may also be implemented in combination in a single embodiment. Conversely, various features described in the context of a single embodiment may also be implemented individually or in any suitable sub-combination in multiple embodiments.

Claims

1. A long-term, multi-point downhole temperature measurement system, characterized in that, include: A downhole measurement unit is used to be deployed inside the wellbore and to collect temperature parameters at multiple depths in the formation. The downhole measurement unit includes multiple downhole instruments connected by a single-core cable. Each downhole instrument includes a temperature sensor, a signal conditioning circuit, an analog-to-digital converter, a main processor, and a bus drive circuit. The multiple downhole instruments are interconnected through an instrument bus located inside the downhole measurement unit. The surface hoisting unit includes a surface winch and its drive control system, used to carry and lower or raise the downhole measurement unit to a predetermined layer via the single-core cable; The ground data acquisition and processing unit is electrically connected to the downhole measurement unit via the single-core cable. It is used to supply power to the downhole measurement unit and interact with the downhole measurement unit. The ground data acquisition and processing unit includes a data decoding unit and a data storage unit. The data decoding unit is used to decode the coded temperature data uploaded via the single-core cable to obtain temperature information. The data storage unit is used to store the temperature information and the time and depth information corresponding to the temperature information. The Internet of Things (IoT) unit is connected to the ground data acquisition and processing unit and is used to send the temperature information to a remote server or cloud platform via a mobile communication network. The single-core cable is used to supply power to the downhole measurement unit and to transmit the coded temperature data.

2. The long-term multi-point downhole temperature measurement system according to claim 1, characterized in that, The instrument bus is a TPS bus, which provides power to multiple downhole instruments simultaneously and carries the temperature data of each downhole instrument via the single-core cable.

3. The long-term multi-point downhole temperature measurement system according to claim 1 or 2, characterized in that, The main processor is configured to perform Manchester encoding on the collected temperature data and couple the Manchester-encoded data to the single-core cable for transmission via the bus driver circuit; the data decoding unit includes a Manchester decoding chip for decoding the Manchester-encoded data transmitted via the single-core cable.

4. The long-term multi-point downhole temperature measurement system according to claim 1, characterized in that, The ground lifting unit includes a variable frequency winch control system, which comprises a noise reduction system, a main control chip, a detection and control module, and an alarm module. The noise reduction system is used to suppress electromagnetic interference generated during the operation of the variable frequency drive unit and the motor. The main control chip is an industrial-grade microcontroller. The detection and control module detects and controls the frequency converter, motor, depth measurement device, and tension sensor via bus and CAN communication. The alarm module outputs a switch alarm signal to trigger external safety devices when the depth or tension exceeds a preset upper limit.

5. The long-term multi-point downhole temperature measurement system according to claim 1, characterized in that, The data storage unit includes a NAND flash memory and a ferroelectric memory. The NAND flash memory is used to store well temperature data, time information, and depth information. The storage capacity of the data storage unit is configured according to the fastest sampling frequency set by the user. The ground data acquisition and processing unit is configured to allow the user to set the sampling time interval for temperature data and the time interval for sending data to the Internet of Things unit.

6. The long-term multi-point downhole temperature measurement system according to claim 1, characterized in that, The IoT unit uses an industrial-grade 4G or GPRS communication module and an external high-gain wall-mounted antenna to stably transmit the temperature information to the remote server or cloud platform in a wide temperature environment.

7. The long-term multi-point downhole temperature measurement system according to claim 1, characterized in that, The measurement system also includes a wellhead device, which includes a cable sealing flange, a water injection port and a water injection valve, a pressure relief port and a pressure relief valve. The cable sealing flange adopts a double-cone sealing structure to achieve wellhead sealing when the single-core cable passes through the wellhead. The pressure relief port and the pressure relief valve are used to release wellhead pressure before and after lowering or raising the downhole measurement unit. The water injection port and the water injection valve are used to inject water into the well during downhole measurement.

8. A method for long-term, multi-point downhole temperature measurement, characterized in that, include: Downhole measurement unit deployment: The downhole measurement unit, which includes multiple downhole instruments, is connected to the surface data acquisition and processing unit via a single-core cable. The multiple downhole instruments are interconnected through an instrument bus located inside the downhole measurement unit and communicate with the surface data acquisition and processing unit via the single-core cable. The downhole measurement unit is lowered to the target layer inside the wellbore using a surface hoisting unit. Temperature acquisition and encoding: Temperature signals at their respective locations are acquired by the temperature sensors of each downhole instrument. These signals are then converted into digital data by a signal conditioning circuit and an analog-to-digital converter. The main processor of the downhole instrument packages and encodes the digital data according to a bus protocol, and the encoded temperature data is coupled to the single-core cable and transmitted to the surface via a bus drive circuit. Ground decoding and storage: The ground data acquisition and processing unit supplies power to the downhole measurement unit through the single-core cable and receives the coded temperature data. The data decoding unit decodes the coded temperature data to obtain the temperature information of each measuring point, and stores the temperature information and the corresponding time and depth information in the data storage unit. Remote transmission and display: The IoT unit receives the temperature information and packages it to send to a remote server or cloud platform via a mobile communication network for remote terminals to query, display and manage.

9. The long-term multi-point downhole temperature measurement method according to claim 8, characterized in that, Before the deployment of the downhole measurement unit, the wellhead device operation steps are also included: opening the pressure relief valve to release the wellhead pressure, unscrewing the cable sealing flange, passing the single-core cable connecting the downhole measurement unit through the center hole of the cable sealing flange and opening the wellhead valve, lowering the downhole measurement unit to the target layer and then tightening the cable sealing flange and closing the pressure relief valve; during the measurement process, water is injected into the well through the water injection port and water injection valve.

10. The long-term multi-point downhole temperature measurement method according to claim 8, characterized in that, In the remote transmission and display step, the remote server generates a temperature gradient curve based on the received temperature information and corresponding depth information, and stores the logging data in a database for long-term archiving and analysis.

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