A wellbore temperature measuring device

Abstract

This application discloses a wellbore temperature measuring device, including a controller, a data acquisition section, a counterweight section, and a connecting section for connecting the data acquisition section and the counterweight section. The data acquisition section is electrically connected to the controller, and an electrically controlled gate is provided at the bottom of the data acquisition section, which is also electrically connected to the controller. The data acquisition section is used to measure and collect various required data. By opening and closing the electrically controlled gate, the position of a strong acid reagent is adjusted, thereby acting on the connecting section, causing the connection between the connecting section and the counterweight section to fail, thus separating the data acquisition section from the counterweight section, allowing for the recovery of the data acquisition section and the acquisition of data. This application has the beneficial effect of enabling accurate measurement of the temperature field inside a single wellbore.

Description

Technical Field

[0001] This invention relates to the field of wellbore temperature field measurement technology, and in particular to a temperature measurement device for single-well coaxial casing geothermal closed-loop mining. Background Technology

[0002] Geothermal energy is an abundant, relatively inexpensive, and widely distributed renewable energy source. Compared with other new energy sources (such as solar, wind, and biomass energy), geothermal energy has advantages such as wide distribution, less susceptibility to external influences (such as day / night cycles, wind speed, and temperature differences), low carbon emissions, and low maintenance costs. The coaxial casing closed-loop heat extraction technology for geothermal wells is a novel geothermal development technology suitable for medium-deep geothermal energy. Existing research results indicate that the insulation structure and high thermal conductivity cement designed in this technology have a positive effect on heat extraction and supply, and also possess advantages such as high heat exchange efficiency and "heat extraction without water extraction."

[0003] The most common method for geothermal resource extraction is direct water extraction for heat generation. However, this method has limitations, and groundwater extraction can cause problems such as groundwater level drop and formation subsidence. The state advocates developing and utilizing geothermal resources using a "heat extraction without water extraction" approach, and the single-well coaxial casing closed-loop heat exchange system aligns perfectly with this initiative. This system achieves "heat extraction without water extraction" and avoids the limitations of reinjection into low-permeability formations and the pollution of groundwater and formations. Furthermore, the system primarily exchanges heat through forced convection of formation water, natural convection within the annular tube, and heat conduction between the wellbore and the formation. This heat transfer method is significantly more effective than the soil-based heat transfer in buried heat pump systems. In addition, this heat exchange system exchanges heat throughout the entire area in contact with the formation, resulting in a much larger heat exchange area than a single-well U-tube downhole heat exchange system.

[0004] Currently, there is a significant demand for underground temperature field measurement in single-well coaxial casing closed heat exchange systems. However, in traditional temperature field measurement methods, the operation of deploying and retrieving the measuring device underground is cumbersome, resulting in long lead times, low temperature measurement efficiency, and impacting subsequent mining operations. Summary of the Invention

[0005] To address the aforementioned problems, this application provides a wellbore temperature measuring device.

[0006] The wellbore temperature measuring device provided in this application adopts the following technical solution:

[0007] A wellbore temperature measuring device includes a controller, a data acquisition section, a counterweight section, and a connecting section for connecting the data acquisition section and the counterweight section, wherein the data acquisition section is electrically connected to the controller;

[0008] The connecting part includes an outer sleeve, an inner sleeve, and a connector. The diameter of the outer sleeve is larger than the diameter of the inner sleeve. Both the outer sleeve and the inner sleeve are fixedly connected to the bottom of the collection part, and the inner sleeve is located inside the outer sleeve.

[0009] A connecting post is fixedly connected to the top of the counterweight part, and the connecting post is inserted into the inner sleeve. The end of the outer sleeve away from the collection part abuts against the top of the counterweight part.

[0010] The outer sleeve sidewall has two opposite locations, the inner sleeve sidewall has two opposite locations, and the connecting post has corresponding and communicating mounting holes. The connector passes through the mounting holes and is installed on the outer sleeve, the inner sleeve, and the connecting post.

[0011] The bottom of the collection section is provided with an installation groove, in which an electrically controlled gate is installed. The electrically controlled gate is located on one side of the connector and divides the inner cavity of the outer sleeve into a reaction chamber and a storage chamber. The connector is located in the reaction chamber, and the storage chamber stores strong acid. The electrically controlled gate is electrically connected to the controller. When the controller controls the electrically controlled gate to open, the electrically controlled gate retracts towards the bottom of the installation groove, and the strong acid enters the reaction chamber to corrode and dissolve the connector.

[0012] Furthermore, the acquisition section includes a cylindrical mounting bracket, a temperature sensor, a CCL positioner, and a recording chip. The temperature sensor, the CCL positioner, and the recording chip are all mounted on the cylindrical mounting bracket, and are all electrically connected to the controller.

[0013] Furthermore, the cylindrical mounting bracket is also equipped with a direction sensor, which is electrically connected to the controller.

[0014] Furthermore, multiple temperature sensors are provided.

[0015] Furthermore, the counterweight portion is cylindrical in shape, and the central axis of the counterweight portion coincides with the central axis of the cylindrical mounting frame.

[0016] Furthermore, the central axis of the outer sleeve and the central axis of the inner sleeve both coincide with the central axis of the cylindrical mounting bracket, and the central axis of the connecting column coincides with the central axis of the counterweight portion.

[0017] Furthermore, a wellbore temperature measurement method based on the wellbore temperature measuring device includes the following steps:

[0018] S1 Well Selection: Manually select wells based on historical information of each well to identify the wells to be tested; S2 Setting Preset Parameter Values: Based on the historical information of the wells to be tested, set the well depth and test time parameters of the wellbore temperature measuring device respectively;

[0019] S3 Pre-measurement Actions: Open the wellhead of the well to be measured and insert the wellbore temperature measuring device;

[0020] S4 Temperature measurement begins: When the wellbore temperature measuring device enters the well, the well depth is calculated in real time through the CCL positioner coupling. At the same time, the temperature sensor measures the current well depth at which the wellbore temperature measuring device is located, and the temperature data and well depth data are written to the recording chip based on the corresponding time.

[0021] S5 Recovering the Acquisition Section: When the wellbore temperature measuring device reaches a predetermined depth downhole, the controller controls the electrical control gate to open, allowing the strong acid to enter the second chamber and contact and dissolve the connector. This continues until the portion of the connector that passes through the inner casing and the connecting column is completely dissolved. At this point, the connecting column separates from the inner casing, and the acquisition section is lifted by buoyancy and recovered at the wellhead. S6 Data Acquisition and Analysis: After recovery, the recording chip is read to acquire and analyze relevant data.

[0022] Furthermore, step S5 also includes the controller controlling the electric gate to open when the wellbore temperature measuring device reaches a predetermined time downhole.

[0023] In summary, this application includes at least one of the following beneficial technical effects:

[0024] This invention enables effective measurement of the temperature field within a single well. It utilizes a two-stage structure to facilitate both sinking and floating within the wellbore. Data is recorded during the descent using sensors and a CCL positioning algorithm. A counterweight ensures the entire device reaches the bottom of the well, guaranteeing accurate measurement of the temperature field within the wellbore. Furthermore, the device is easy to deploy and retrieve, eliminating the need for mechanical retrieval and saving time. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the structure of a wellbore temperature measuring device according to an embodiment of this application.

[0026] Figure 2 This is a schematic diagram showing the position of the electrically controlled gate in an embodiment of this application.

[0027] Figure 3 This is a schematic diagram of the counterweight portion in an embodiment of this application.

[0028] Figure 4 This is a schematic diagram illustrating the electrical connection between the controller and the electrically controlled gate in the embodiments of this application.

[0029] Figure 5 This is a schematic diagram illustrating the structure of the data acquisition section in the embodiments of this application.

[0030] Explanation of reference numerals in the attached figures:

[0031] 1. Acquisition section; 101. Cylindrical mounting bracket; 102. CCL positioner; 103. Recording chip; 104. Temperature sensor; 105. Direction sensor; 2. Counterweight section; 3. Outer sleeve; 4. Inner sleeve; 5. Connector; 6. Connecting post; 7. Mounting hole; 8. Electrically controlled gate; 9. Reaction chamber; 10. Storage chamber. Detailed Implementation

[0032] The following is in conjunction with the appendix Figure 1-5 This application will be described in further detail.

[0033] Currently, there are many development schemes for deep geothermal energy, mainly including open-loop and closed-loop extraction methods. The main difference lies in whether the heat exchange medium is mixed with the formation fluid. In the closed-loop extraction method, the heat exchange medium is water injected into the wellbore from the surface and is not mixed with the formation fluid. Instead of mixing the fluids for heating, the water in the wellbore circulates within a single well to obtain heat from the bottom layer. Only heat is extracted, not formation water. Therefore, the downhole temperature field can help determine the downhole temperature and development potential. Thus, the single-well "heat extraction without water extraction" approach requires a clear understanding of the downhole temperature field for effective development.

[0034] In order to accurately and effectively measure the temperature field in a single well, this application discloses a wellbore temperature measuring device.

[0035] Reference Figures 1 to 4 A wellbore temperature measuring device includes a controller, a data acquisition part 1, a counterweight part 2, and a connecting part for connecting the data acquisition part 1 and the counterweight part 2. The data acquisition part 1 is electrically connected to the controller.

[0036] Reference Figure 1 , Figure 4 and Figure 5To effectively and accurately measure downhole temperature, the acquisition unit 1 includes a cylindrical mounting frame 101, a CCL locator 102, a recording chip 103, and multiple temperature sensors 104. The CCL locator 102 is used for real-time depth calculation via a coupling; the temperature sensors 104 measure the temperature at the current well depth; and the recording chip 103 records time, various data, and the opening / closing status of the electrically controlled gate 8. The temperature sensors 104, CCL locator 102, and recording chip 103 are all mounted on the cylindrical mounting frame 101 and are electrically connected to the controller. Furthermore, to more accurately determine the device's direction of movement, distinguish between the downhole and return processes, and further verify and improve measurement accuracy, a direction sensor 105 is also mounted on the cylindrical mounting frame 101 and is electrically connected to the controller.

[0037] Reference Figure 1 and Figure 2 The connecting part includes an outer sleeve 3, an inner sleeve 4, and a connector 5. The diameter of the outer sleeve 3 is larger than the diameter of the inner sleeve 4. Both the outer sleeve 3 and the inner sleeve 4 are fixedly connected to the bottom of the cylindrical mounting bracket 101. The inner sleeve 4 is located inside the outer sleeve 3. The central axis of the outer sleeve 3 and the central axis of the inner sleeve 4 are both coincident with the central axis of the cylindrical mounting bracket 101. The connector 5 is specifically a connecting rod.

[0038] Reference Figure 1 and Figure 3 The counterweight part 2 is cylindrical in shape, and a connecting column 6 is fixedly connected to the top of the counterweight part 2. The central axis of the connecting column 6 coincides with the central axis of the counterweight part 2. The connecting column 6 is inserted into the inner sleeve 4. The central axis of the counterweight part 2 coincides with the central axis of the cylindrical mounting frame 101. The end of the outer sleeve 3 away from the cylindrical mounting frame 101 abuts against the top of the counterweight part 2.

[0039] Reference Figure 1 , Figure 2 and Figure 3 Two corresponding and interconnected mounting holes 7 are provided on two opposite parts of the side wall of the outer sleeve 3, two opposite parts of the side wall of the inner sleeve 4, and the connecting post 6. The connector 5 passes through the mounting holes 7 and is installed on the outer sleeve 3, the inner sleeve 4, and the connecting post 6.

[0040] Reference Figures 1 to 5The bottom of the collection section 1 has two mounting slots located on both sides of the connector 5. Each mounting slot contains a corresponding electrically controlled gate 8. The two electrically controlled gates 8, located on both sides of the connector 5, divide the inner cavity of the outer sleeve 3 into a reaction chamber 9 and two storage chambers 10. The connector 5 is located in the reaction chamber 9. Both storage chambers 10 are pre-stored with strong acid. The two electrically controlled gates 8 are electrically connected to the controller. The operator can configure the controller according to the actual situation, thereby controlling one or both electrically controlled gates 8 to open (and / or close). When the electrically controlled gate 8 is in the closed state, the end of the electrically controlled gate 8 away from the collection section 1 is pressed against the top of the counterweight section 2. When the electrically controlled gate 8 receives an opening signal from the controller, the electrically controlled gate 8 moves towards the bottom of the mounting slot and retracts into the mounting slot. The strong acid enters the reaction chamber 9, contacts and corrodes the connector 5.

[0041] Based on the above-mentioned wellbore temperature measuring device, this application also discloses a wellbore temperature measuring method, referring to... Figures 1 to 5 The measurement method specifically includes the following steps:

[0042] S1 Well Selection: Based on the basic information of each well, manual well selection is conducted to identify wells to be tested. Specifically, firstly, abandoned wells are selected for geothermal extraction, and secondly, wells with good total temperature fields in their past production history are selected from the abandoned wells. Both are preliminary selection processes.

[0043] S2 sets preset parameter values ​​for the measuring device: based on the basic information of the well to be measured, the well depth and testing time are set separately. Specifically, the basic information refers to various aspects of the well to be measured, such as: CCL calculates the depth by the number of couplings, the number of couplings can be determined by the number of tubing strings run, and then the approximate downhole location, well inclination, casing damage and deformation, etc., to determine whether it will affect the running of downhole development equipment and calculate development costs, etc.

[0044] S3 Pre-measurement Actions: Open the wellhead of the well to be measured and insert the wellbore temperature measuring device.

[0045] S4 Temperature Measurement Begins: When the wellbore temperature measuring device enters the well, the well depth is calculated in real time via the CCL locator 102 coupling. Simultaneously, the temperature sensor 104 measures the current well depth at which the wellbore temperature measuring device is located, and writes the temperature data to the recording chip 103 based on the corresponding well depth. Specifically, during the initial measurement process, as the device is continuously lowered into the well, under the control of the controller, each sensor detects and feeds back relevant data. The controller writes the received data to the recording chip 103 accordingly. This data includes time, well depth, and temperature. The well depth is calculated with the assistance of the CCL locator 102, and the direction sensor 105 can more accurately determine the precise direction of the device's descent, determining the final inclination and vertical depth calculations. The temperature is detected and fed back by the temperature sensor 104.

[0046] S5 Recovery and Collection Section 1: When the wellbore temperature measuring device reaches a predetermined depth or time downhole, the controller controls the drive mechanism to open the electrically controlled gate 8, allowing the strong acid to contact and dissolve the connector 5. This continues until the portion of the connector 5 passing through the inner casing 4 and the connecting column 6 is completely dissolved. At this point, the connecting column 6 separates from the inner casing 4, and the collection section 1 floats up due to buoyancy, allowing for recovery at the wellhead. The counterweight section 2 remains downhole due to gravity. In practice, dilute sulfuric acid can be used to achieve this step. To prevent dissolution or corrosion by dilute sulfuric acid, the materials of the cylindrical mounting bracket 101, outer casing 3, and inner casing 4 must be selected for their good resistance to strong acids. For example, stainless steel can be used for the cylindrical mounting bracket 101, outer casing 3, and inner casing 4. In particular, chromium-nickel austenitic stainless steel and duplex stainless steel pipes containing molybdenum, copper, and silicon (3%–4%) have better sulfuric acid resistance. To facilitate the dissolution of connector 5 by dilute sulfuric acid, connector 5 can be made of a reactive metal, such as magnesium or iron. For example, if dilute sulfuric acid is chosen as the strong acid and magnesium is chosen as the material for connector 5, the connector 5 can be dissolved by the displacement reaction that occurs between the dilute sulfuric acid and magnesium.

[0047] S6 Data Acquisition and Analysis: After recycling, disassemble the acquisition section 1 to remove the chip, read the recording chip 103, acquire relevant data and perform analysis.

[0048] The implementation principle of a wellbore temperature measuring device according to an embodiment of this application is as follows:

[0049] In practical applications, the wellbore temperature measuring device described in this application connects the acquisition part 1 and the counterweight part 2 together via a connector 5. This allows the device to continuously descend within the well and measure relevant data such as time, well depth, and temperature. After the temperature measurement is completed, the acquisition part 1 and the counterweight part 2 can be separated, transforming the device into a "two-stage structure" that descends and rises separately within the wellbore. This temperature measuring device is convenient to deploy and retrieve, and requires no mechanical retrieval during retrieval, saving time.

[0050] The temperature sensor 104, orientation sensor 105, and CCL positioner 102 in the data acquisition section 1 record relevant data during the descent process. The gravity of the counterweight section 2 ensures that the entire measuring device can be lowered to the bottom of the well, thereby ensuring accurate measurement of the temperature field inside the single wellbore. In summary, this invention has the advantages of simple operation, high measurement efficiency, and accurate data, which can save development costs and improve economic benefits.

[0051] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A wellbore temperature measuring device, characterized in that: It includes a controller, a data acquisition part (1), a counterweight part (2), and a connection part for connecting the data acquisition part (1) and the counterweight part (2), wherein the data acquisition part (1) is electrically connected to the controller; The connecting part includes an outer tube (3), an inner tube (4) and a connector (5). The diameter of the outer tube (3) is larger than the diameter of the inner tube (4). The outer tube (3) and the inner tube (4) are both fixedly connected to the bottom of the collection part (1). The inner tube (4) is located inside the outer tube (3). A connecting post (6) is fixedly connected to the top of the counterweight part (2). The connecting post (6) is inserted into the inner sleeve (4). The outer sleeve (3) is located away from the collection part (1) and abuts against the top of the counterweight part (2). The outer sleeve (3) has two opposite parts on its side wall, the inner sleeve (4) has two opposite parts on its side wall, and the connecting post (6) has corresponding and communicating mounting holes (7). The connector (5) passes through the mounting holes (7) and is installed on the outer sleeve (3), the inner sleeve (4), and the connecting post (6). The bottom of the collection part (1) is provided with an installation groove, and an electrically controlled gate (8) is installed in the installation groove. The electrically controlled gate (8) is located on one side of the connector (5) and divides the inner cavity of the outer sleeve (3) into a reaction chamber (9) and a storage chamber (10). The connector (5) is located in the reaction chamber (9). The storage chamber (10) stores strong acid. The electrically controlled gate (8) is electrically connected to the controller. When the controller controls the electrically controlled gate (8) to open, the electrically controlled gate (8) retracts towards the bottom of the installation groove, and the strong acid enters the reaction chamber (9) to corrode and dissolve the connector (5).

2. A wellbore temperature measuring device according to claim 1, characterized in that: The acquisition section (1) includes a cylindrical mounting bracket (101), a temperature sensor (104), a CCL locator (102), and a recording chip (103). The temperature sensor (104), the CCL locator (102), and the recording chip (103) are all mounted on the cylindrical mounting bracket (101), and the temperature sensor (104), the CCL locator (102), and the recording chip (103) are all electrically connected to the controller.

3. A wellbore temperature measuring device according to claim 2, characterized in that: The cylindrical mounting bracket (101) is also equipped with a direction sensor (105), which is electrically connected to the controller.

4. A wellbore temperature measuring device according to claim 2, characterized in that: Multiple temperature sensors (104) are provided.

5. A wellbore temperature measuring device according to claim 2, characterized in that: The counterweight part (2) is cylindrical in shape, and the central axis of the counterweight part (2) coincides with the central axis of the cylindrical mounting frame (101).

6. A wellbore temperature measuring device according to claim 2, characterized in that: The central axis of the outer sleeve (3) and the central axis of the inner sleeve (4) are both coincident with the central axis of the cylindrical mounting bracket (101), and the central axis of the connecting column (6) coincides with the central axis of the counterweight part (2).

7. A wellbore temperature measuring device according to claim 2, characterized in that: A wellbore temperature measurement method based on the wellbore temperature measuring device includes the following steps: S1 Well Selection: Wells are manually selected based on historical information from each well to identify the wells to be tested. S2 Set preset parameter values: Based on the historical information of the well to be tested, the wellbore temperature measuring device sets the two parameters of well depth and test time respectively; S3 Pre-measurement Actions: Open the wellhead of the well to be measured and insert the wellbore temperature measuring device; S4 Temperature measurement begins: When the wellbore temperature measuring device enters the well, the well depth is calculated in real time through the CCL locator (102) coupling, and the temperature is measured at the current well depth of the wellbore temperature measuring device through the temperature sensor (104). The temperature data and well depth data are written into the recording chip (103) based on the corresponding time. S5 Recovers the collection part (1): When the wellbore temperature measuring device reaches a predetermined depth downhole, the controller controls the electric control gate (8) to open, so that the strong acid enters the reaction chamber (9) to contact and dissolve the connector (5) until the part of the connector (5) that passes through the inner casing (4) and the connecting column (6) is completely dissolved, the connecting column (6) separates from the inner casing (4), and the collection part (1) is lifted up by buoyancy and recovered at the wellhead; S6 Data Acquisition and Analysis: After recovery, the recording chip (103) is read to acquire relevant data and perform analysis.

8. A wellbore temperature measuring device according to claim 7, characterized in that: Step S5 further includes that when the wellbore temperature measuring device reaches a predetermined time downhole, the controller controls the electrically controlled gate (8) to open.

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