Non-contact type abandoned well safety monitoring system and method

Abstract

The invention provides a non-contact type abandoned well safety monitoring system and method.The system comprises a ground control cabinet, an underground tester, a well leaving intelligent device and a plurality of underground sensors, the ground control cabinet is connected with the underground tester through a cable and supplies power to the underground tester, and the underground sensor is connected with the underground tester through a cable; the ground control cabinet is connected with the underground tester, bidirectional communication between the ground control cabinet and the underground tester is carried out, bidirectional wireless communication between the underground tester and the well-staying intelligent device is realized through electromagnetic waves, the underground tester supplies power to the well-staying intelligent device through the electromagnetic waves, and the well-staying intelligent device is solidified in a cement plug on the uppermost layer. And the plurality of underground sensors are connected through cables. According to the non-contact type abandoned well safety monitoring system and method, testing of cement plug descending of an abandoned well is achieved for the first time, testing of physical parameters of the lower portion of the cement plug can be achieved by descending an underground tester, all electronic components are packaged in a mechanical shell and are not electrically connected with the outside, and the service life of the electronic components is longer.

Description

Technical Field

[0001] The invention relates to the technical field of oilfield development, and in particular to a non-contact abandoned well safety monitoring system and method. Background Art

[0002] As oilfield development enters the middle and late stages, a large number of production wells are no longer worth exploiting and using due to geological or engineering reasons and are classified as abandoned wells. At present, the commonly used treatment solution for abandoned wells is to inject one or more cement plugs into the abandoned wells. The length and number of cement plugs vary according to different domestic and international standards. After the cement plugs are injected, the temperature and pressure of the production layer and casing cement ring of the abandoned well may change due to changes in the oil production or water injection pressure of the adjacent wells. Therefore, abandoned wells pose potential safety risks.

[0003] Patent CN108661622B relates to a method for testing the plugging effect of a waste gas well in a gas storage facility. The invention discloses a method for testing the plugging effect of an abandoned well in a gas storage facility, and belongs to the field of well repair operations. The method comprises: clearing the wellbore above the cement plug in the abandoned well. While lowering the MFE test string into the wellbore, clean water is injected into the MFE test string to form a liquid cushion, ensuring that the reservoir pressure below the cement plug is greater than the liquid cushion pressure in the MFE test string. After the MFE test string is lowered to a predetermined depth, the MFE test string is sealed at the wellbore 50-100m away from the top surface of the cement plug. The MFE test string is used to open and close the well, and the test pressure in the MFE test string during the closing period is obtained. If the difference between the test pressure and the liquid cushion pressure is less than or equal to 0.5MPa, the plugging is qualified, otherwise, it is unqualified. This method has high testing accuracy and will not damage the cement plug.

[0004] Patent CN115452256A provides a closed wall performance test device and method for compressed gas energy storage in abandoned shaft space, which relates to the technical field of rock mechanics test devices. The device includes a box body, a water pressure sealing cover, an air pressure sealing cover, a water-filled cavity, an air-filled cavity, a truncated cone cavity, a water supply pipeline, a loading system and a monitoring device. Concrete is poured in the box body, and the upper bottoms at both ends of the truncated cone cavity are respectively connected to the water-filled cavity and the air-filled cavity. The water supply pipeline is connected to the water-filled cavity, and the air pump is connected to the air-filled cavity. The loading system simulates the pressure of the overlying surrounding rock and the lateral surrounding rock, and the monitoring device determines the stress and displacement changes in the closed wall. By using this device to conduct experiments, the air tightness can be judged by detecting the ion concentration of the liquid in the water-filled cavity. Through simulation, the air tightness of the closed wall under different water pressures, air pressures, and surrounding rock pressures, as well as stress, displacement, etc. can also be detected.

[0005] Patent CN207440306U provides a deep-buried abandoned well detection device, including a magnetizing coil and a posture measurement module, a vector data detection module and a host installed on a back frame. Two high-precision GPS are installed in the horizontal direction on the top of the back frame. The vector sensor module is installed at the bottom of the support rod, as close to the ground as possible. The sensor support rod and the back frame are connected by a universal joint to keep the sensor support rod always vertically downward when the back frame moves. The data acquisition system uses a computer, which is connected to the GPS and vector sensor through a cable to control and receive GPS and vector sensor data, and display and analyze in real time; the magnetizing coil can emit a pulse voltage of a fixed frequency after being energized to generate an artificial magnetic field to fully magnetize the metal body. Compared with the prior art, the utility model can realize comprehensive detection of the entire survey area plane, overcome the drawbacks of repeated work and omissions in the prior art, greatly improve the detection efficiency and accuracy, and reduce the occurrence of false detection and missed detection; at the same time, the setting of the artificial magnetic field solves the defect of low detection accuracy of deep-buried abandoned wells.

[0006] The above-mentioned comparative patents disclose a test method for the plugging effect of abandoned wells in gas storage facilities, a closed wall performance test device and method for compressed gas storage in abandoned wells, and a deep-buried abandoned well detection device. The above three patents involve testing methods for abandoned wells, but they are different from the principles and methods of the present invention. Currently, there is no existing literature or patents showing that there is no simple and effective method for real-time monitoring of abandoned wells, which fails to solve the technical problem we want to solve. For this reason, we have invented a new non-contact abandoned well safety monitoring system and method. Summary of the invention

[0007] The object of the present invention is to provide a non-contact abandoned well safety monitoring system and method which realizes the testing of cement plugs in abandoned wells and can test the physical parameters of the lower part of the cement plug by lowering a downhole tester.

[0008] The objective of the present invention can be achieved through the following technical measures: a non-contact abandoned well safety monitoring system, which includes a ground control cabinet, a downhole tester, a well-retaining intelligent device and multiple downhole sensors. The ground control cabinet and the downhole tester are connected by a cable to power the downhole tester and perform two-way communication between the ground control cabinet and the downhole tester. The downhole tester and the well-retaining intelligent device perform two-way wireless communication through electromagnetic waves, and the downhole tester powers the well-retaining intelligent device through electromagnetic waves. The well-retaining intelligent device is solidified in the topmost cement plug, and the multiple downhole sensors are connected by cables.

[0009] The purpose of the present invention can also be achieved by the following technical measures:

[0010] The cement plug has multiple levels, and a downhole sensor is installed at the bottom of each level of the cement plug.

[0011] Cement plugs are permanently placed in the well. The length, number and depth of the cement plugs should be based on relevant abandoned well standards.

[0012] The downhole sensor has multiple testing functions, including but not limited to temperature, pressure, and toxic gas testing.

[0013] The well-retaining intelligent device has no power supply inside and is in a passive and unpowered state when in the well for a long time. The upper end of the well-retaining intelligent device is open, and the downhole tester is lowered into the well through a cable and inserted into the well-retaining intelligent device for docking.

[0014] The well retention intelligent device comprises a circuit part and a mechanical part.

[0015] The circuit part comprises a first wireless communication coil, a second wireless power supply coil, a power supply module, a communication module, a main control module and a sensor driving module. The second wireless power supply coil is connected to the power supply module through wires to supply power to each module of the well-retaining intelligent device; the first wireless communication coil is connected to the communication module through wires to realize two-way communication between the well-retaining intelligent device and the downhole measurement and control instrument; the power supply module supplies power to the communication module, the main control module and the sensor driving module through wires; the main control module is connected to the communication module through wires to realize two-way communication; the sensor driving module is connected to the multiple downhole sensors through cables; the main control module is connected to the sensor module through wires to supply power to the sensor module and read signals from the multiple downhole sensors.

[0016] The mechanical structure includes an outer cylinder and an inner cylinder. The inner cylinder is hollow, with an open upper end and a closed lower end. The outer side of the inner cylinder is wound with the first wireless communication coil and the second wireless power supply coil from top to bottom. The first wireless communication coil and the second wireless power supply coil are located in an annular space formed by the outer cylinder and the inner cylinder. The power supply module, the communication module, the main control module, and the sensor driving module are located inside the outer cylinder, at the lower part of the inner cylinder.

[0017] The downhole tester includes a cable communication module, a power module, a second main control module, a wireless communication module, a second power supply module, a third wireless communication coil, and a fourth wireless power supply coil. The power module is connected to the cable communication module, the second main control module, the wireless communication module, and the second power supply module through wires and supplies power; the cable connected to the ground control cabinet is connected to the power module and supplies power, and is connected to the cable communication module for bidirectional communication; the second main control module is respectively connected to the cable communication module and the wireless communication module to achieve bidirectional communication; the wireless communication module is connected to the third wireless communication coil; and the second power supply module is connected to the fourth wireless power supply coil.

[0018] The fourth wireless power supply coil is located at the lowest end of the downhole measurement and control instrument, and the third wireless communication coil is located at the upper part of the fourth wireless power supply coil; when the downhole measurement and control instrument is inserted into the upper end of the well-retention intelligent device, the fourth wireless power supply coil and the third wireless communication coil at the lowest end of the downhole measurement and control instrument correspond to the physical positions of the second wireless power supply coil and the first wireless communication coil at the upper end of the well-retention intelligent device.

[0019] The purpose of the present invention can also be achieved by the following technical measures: a non-contact abandoned well safety monitoring method, which adopts a non-contact abandoned well safety monitoring system, including:

[0020] Step 1: Connect the lower part of the well-retaining intelligent device to multiple downhole sensors through cables at the wellhead to test the changes in physical parameters of the lower part of the cement plug;

[0021] Step 2, the well-retaining intelligent device is solidified in the wellbore together with the cement plug, the opening of the well-retaining intelligent device is upward, and it is located on the upper part of the uppermost cement plug; multiple downhole sensors connected to the well-retaining intelligent device are sequentially located in the lower space of each level of cement plug; the number of sensors is the same as the number of cement plugs;

[0022] Step 3, when it is necessary to test the physical parameters of the lower part of the cement plug, connect the downhole tester through a cable from the wellhead, lower the downhole tester into the well, and conduct two-way communication with the well intelligent device through electromagnetic waves to test the physical parameters of the lower part of the cement plug;

[0023] Step 4: After the test is completed, pull the cable and lift the downhole tester out of the wellhead.

[0024] The purpose of the present invention can also be achieved by the following technical measures:

[0025] In step 3, the downhole tester also supplies power to the well-retaining intelligent device through electromagnetic waves.

[0026] The non-contact abandoned well safety monitoring system and method in the present invention creatively realizes the testing of cement plugs in abandoned wells for the first time. The physical parameters of the lower part of the cement plug can be tested by inserting a downhole tester. The length and number of cement plugs do not affect the test function. The non-contact abandoned well safety monitoring system does not contain batteries, and its life is not affected by batteries. It is in a power-off state in the well for a long time. When the production of the adjacent well is dynamically adjusted, the reservoir can be dynamically monitored by monitoring the pressure changes of the production layer of the abandoned well; all electronic components of the non-contact abandoned well safety monitoring system are encapsulated in a mechanical housing, with no electrical connection to the outside world, and the life of the electronic components is longer. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1It is a schematic diagram of the non-contact abandoned well safety monitoring system and the well structure of the present invention;

[0028] Figure 2 A schematic diagram of an intelligent well retention device in a specific embodiment of the present invention;

[0029] Figure 3 It is a top view of the mechanical structure of the well retention intelligent device in a specific embodiment of the present invention;

[0030] Figure 4 It is a side view of the mechanical structure of the well retention intelligent device in a specific embodiment of the present invention;

[0031] Figure 5 It is a schematic diagram of a downhole tester in a specific embodiment of the present invention. DETAILED DESCRIPTION

[0032] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0033] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations and / or combinations thereof.

[0034] The non-contact abandoned well safety monitoring system of the present invention includes a ground control cabinet, a downhole tester, a well-retaining intelligent device and multiple downhole sensors. The ground control cabinet and the downhole tester are connected by a cable to power the downhole tester and perform two-way communication between the ground control cabinet and the downhole tester. The downhole tester and the well-retaining intelligent device achieve two-way wireless communication through electromagnetic waves, and the downhole tester powers the well-retaining intelligent device through electromagnetic waves. The well-retaining intelligent device is solidified in the topmost cement plug and is connected to the multiple downhole sensors through cables.

[0035] The non-contact abandoned well safety monitoring method of the present invention is to solidify the non-contact downhole safety measurement and control system in the wellbore together with the cement plug. The lower part of the non-contact downhole safety measurement and control system is connected to multiple sensors through cables to test the changes in the physical parameters of the lower part of the cement plug. There is no battery inside the non-contact abandoned well safety monitoring system. When it is necessary to test the physical parameters of the lower part of the cement plug, a downhole tester is connected from the wellhead through a cable. The downhole tester is lowered into the well, and two-way communication is carried out with the non-contact abandoned well safety monitoring system through electromagnetic waves. The downhole safety measurement and control device is powered by electromagnetic waves, thereby realizing the test of the physical parameters of the lower part of the cement plug; after the test is completed, the cable is pulled to lift the downhole tester out of the wellhead.

[0036] The following are several specific embodiments of the present invention.

[0037] Example 1

[0038] In a specific embodiment 1 of the present invention, a non-contact abandoned well safety monitoring system is provided. Figure 1 As shown, it includes: a ground control cabinet 1, a downhole tester 2, a well-retaining intelligent device 3, a first cement plug 4, a first sensor 5, a second cement plug 6, a second sensor 7, a third cement plug 8, a third sensor 9, and a casing 10. The ground control cabinet 1 and the downhole tester 2 are connected by a cable to realize power supply to the downhole tester 2 and realize two-way communication between the ground control cabinet 1 and the downhole tester 2; the downhole tester 2 and the well-retaining intelligent device 3 realize two-way wireless communication through electromagnetic waves, and the downhole tester 2 realizes power supply to the well-retaining intelligent device 3 through electromagnetic waves.

[0039] The well-retaining intelligent device 3 is solidified in the top cement plug and connected to multiple sensors downhole through a cable. A downhole sensor is installed at the bottom of each cement plug, a first sensor 5 is installed at the bottom of the first cement plug 4, a second sensor 7 is installed at the bottom of the second cement plug 6, and a third sensor 9 is installed at the bottom of the third cement plug 8.

[0040] The casing 10 is a steel metal material with a cylindrical structure, and is connected from the wellhead to the bottom of the well by a plurality of metal pipes with buckles at both ends. The function of the casing 10 is to cement the well, fix the formation sediment, and prevent the well wall from collapsing.

[0041] Downhole sensors have one or more parameter testing functions, such as temperature, pressure, and toxic gas testing. Cement plugs are permanently placed in the well. The length, number, and depth of the cement plugs should be based on relevant abandoned well standards. There is no power supply inside the well-retaining intelligent device, and it is in a passive and unpowered state when it is in the well for a long time. The upper end of the well-retaining intelligent device is open, and the downhole tester is lowered into the well through a cable and inserted into the well-retaining intelligent device to connect with it.

[0042] Example 2

[0043] In a specific embodiment 3 of the present invention, the well-retaining intelligent device is solidified in the upper section of the topmost cement plug, and mainly comprises a circuit part and a mechanical part.

[0044] The well retention intelligent device, wherein the circuit part includes, Figure 2 As shown: wireless communication coil a1, wireless power supply coil a2, power supply module a3, communication module a4, main control module a5, sensor drive module a6. The wireless power supply coil a2 is connected to the power supply module a3 through wires to supply power to each module circuit of the well-retaining intelligent device; the wireless communication coil a1 is connected to the communication module a4 through wires to realize two-way communication between the well-retaining intelligent device and the downhole measuring and controlling instrument; the power supply module a3 supplies power to the communication module a4, the main control module a5, and the sensor drive module a6 through wires; the main control module a5 is connected to the communication module a4 through wires to realize two-way communication; the main control module a5 is connected to the sensor module a6 through wires to realize the sensor signal reading of the sensor module a6; the sensor drive module a6 is connected to multiple sensors downhole through cables.

[0045] The intelligent well retention device, wherein the mechanical part is as follows Figure 3 and Figure 4 As shown. The mechanical structure consists of an outer cylinder c1 and an inner cylinder c2; the inner cylinder c2 is hollow, open at the upper end and closed at the lower end. The outer side of the inner cylinder c2 is wound with a wireless communication coil a1 and a wireless power supply coil a2 from top to bottom, and the two coils are located in the annular space formed by the outer cylinder c1 and the inner cylinder c2. The power supply module a3, the communication module a4, the main control module a5, and the sensor drive module a6 are located inside the outer cylinder c1, at the lower part of the inner cylinder c2.

[0046] Example 3

[0047] In a specific embodiment 3 of the present invention, a downhole tester such as Figure 5 As shown, it includes: cable b0, cable communication module b1, power module b2, main control module b3, wireless communication module b4, power supply module b5, wireless communication coil b6, and wireless power supply coil b7; cable b0 is connected to the ground control cabinet 1; power module b2 is connected to the cable communication module b1, main control module b3, wireless communication module b4, and power supply module b5 through wires and supplies power; cable b0 is connected to the power module b2 and supplies power, and is connected to the cable communication module b1 and communicates bidirectionally; main control module b3 is respectively connected to the cable communication module b1 and the wireless communication module b4 and realizes bidirectional communication; wireless communication module b4 is connected to the wireless communication coil b6; power supply module b5 is connected to the wireless power supply coil b7;

[0048] The positions of the functional modules of the downhole tester are as follows: the wireless power supply coil b7 is located at the lowest end of the downhole measuring and controlling instrument, and the wireless communication coil b6 is located at the upper part of the wireless power supply coil b7; when the downhole measuring and controlling instrument is inserted into the upper end of the well-retaining intelligent device, the wireless power supply coil b7 and the wireless communication coil b6 at the lowest end of the downhole measuring and controlling instrument correspond to the physical positions of the wireless power supply coil a2 and the wireless communication coil a1 at the upper end of the well-retaining intelligent device.

[0049] Example 4

[0050] In a specific embodiment 4 of the present invention, the working principle of the non-contact abandoned well safety monitoring system is introduced in three parts: two-way communication and one-way power supply.

[0051] The working principle of the two-way communication part is: from the wellhead to the underground communication, the ground control cabinet 1 transmits the communication signal to the underground measurement and control instrument 2 through the cable. The cable communication module b1 in the underground measurement and control instrument 2 converts the signal into a signal that can be recognized by the main control module b3. After analysis, the main control module b3 sends the communication signal to the wireless communication module b4, and the wireless communication module b4 sends the communication signal to the wireless communication coil b6; then it is sent to the space in the wellbore through electromagnetic waves; in the well-retaining intelligent device 3, the wireless communication coil a1 receives the electromagnetic wave and transmits it to the communication module a4, and then transmits it to the main control module a5. After the main control module a5 analyzes the instruction, it sends a read signal instruction to the sensor drive module a6; from the underground to the wellhead communication, the motor monitoring circuit in the sensor drive module a6 transmits the parameter signals of each underground sensor to the main control module a5, and then a4, a1, b6, b4, b3, b1, b0, 1;

[0052] Power supply working principle: the control cabinet 1 transmits electric energy to the power module b2 in the downhole measurement and control instrument 2 through a cable. After the voltage of b2 is converted, it supplies power to the modules b3, b4 and b5 respectively. After the b5 module performs high-frequency inversion and resonance compensation on the current, it is coupled to the wireless power supply coil b7 and sent to the space in the wellbore. After the wireless power supply coil a2 in the well-retaining intelligent device 3 receives the wireless power signal, it is sent to the power supply module a3. After the voltage is converted, the power supply module a3 supplies power to the sensor drive module a6, the main control module a5 and the communication module a4 respectively.

[0053] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions recorded in the aforementioned embodiments or replace some of the technical features therein with equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

[0054] Except for the technical features described in the specification, all other technical features are known technologies to those skilled in the art.

Claims

1. Non-contact abandoned well safety monitoring system, characterized in that: The non-contact abandoned well safety monitoring system includes a ground control cabinet, a downhole tester, an intelligent device for retaining the well and multiple downhole sensors. The ground control cabinet and the downhole tester are connected by a cable to power the downhole tester and perform two-way communication between the ground control cabinet and the downhole tester. The downhole tester and the intelligent device for retaining the well achieve two-way wireless communication through electromagnetic waves, and the downhole tester powers the intelligent device for retaining the well through electromagnetic waves. The intelligent device for retaining the well is solidified in the topmost cement plug and is connected to the multiple downhole sensors through cables.

2. The non-contact abandoned well safety monitoring system according to claim 1 is characterized in that: The cement plug has multiple levels, and a downhole sensor is installed at the bottom of each level of the cement plug.

3. The non-contact abandoned well safety monitoring system according to claim 2 is characterized in that: Cement plugs are permanently placed in the well. The length, number and depth of the cement plugs should be based on relevant abandoned well standards.

4. The non-contact abandoned well safety monitoring system according to claim 1 is characterized in that: The downhole sensor has multiple testing functions, including temperature, pressure, and toxic gas testing.

5. The non-contact abandoned well safety monitoring system according to claim 1 is characterized in that: The well-retaining intelligent device has no power supply inside and is in a passive and unpowered state when in the well for a long time. The upper end of the well-retaining intelligent device is open, and the downhole tester is lowered into the well through a cable and inserted into the well-retaining intelligent device for docking.

6. The non-contact abandoned well safety monitoring system according to claim 1, characterized in that: The well retention intelligent device comprises a circuit part and a mechanical part.

7. The non-contact abandoned well safety monitoring system according to claim 6, characterized in that: The circuit part comprises a first wireless communication coil, a second wireless power supply coil, a power supply module, a communication module, a main control module and a sensor driving module. The second wireless power supply coil is connected to the power supply module through wires to supply power to each module of the well-retaining intelligent device; the first wireless communication coil is connected to the communication module through wires to realize two-way communication between the well-retaining intelligent device and the downhole measurement and control instrument; the power supply module supplies power to the communication module, the main control module and the sensor driving module through wires; the main control module is connected to the communication module through wires to realize two-way communication; the sensor driving module is connected to the multiple downhole sensors through cables; the main control module is connected to the sensor module through wires to supply power to the sensor module and read signals from the multiple downhole sensors.

8. The non-contact abandoned well safety monitoring system according to claim 7, characterized in that: The mechanical structure includes an outer cylinder and an inner cylinder. The inner cylinder is hollow, with an open upper end and a closed lower end. The outer side of the inner cylinder is wound with the first wireless communication coil and the second wireless power supply coil from top to bottom. The first wireless communication coil and the second wireless power supply coil are located in an annular space formed by the outer cylinder and the inner cylinder. The power supply module, the communication module, the main control module, and the sensor driving module are located inside the outer cylinder, at the lower part of the inner cylinder.

9. The non-contact abandoned well safety monitoring system according to claim 8, characterized in that: The downhole tester includes a cable communication module, a power module, a second main control module, a wireless communication module, a second power supply module, a third wireless communication coil, and a fourth wireless power supply coil. The power module is connected to the cable communication module, the second main control module, the wireless communication module, and the second power supply module through wires and supplies power; the cable connected to the ground control cabinet is connected to the power module and supplies power, and is connected to the cable communication module for bidirectional communication; the second main control module is respectively connected to the cable communication module and the wireless communication module to achieve bidirectional communication; the wireless communication module is connected to the third wireless communication coil; and the second power supply module is connected to the fourth wireless power supply coil.

10. The non-contact abandoned well safety monitoring system according to claim 9, characterized in that: The fourth wireless power supply coil is located at the lowest end of the downhole measurement and control instrument, and the third wireless communication coil is located at the upper part of the fourth wireless power supply coil; when the downhole measurement and control instrument is inserted into the upper end of the well-retention intelligent device, the fourth wireless power supply coil and the third wireless communication coil at the lowest end of the downhole measurement and control instrument correspond to the physical positions of the second wireless power supply coil and the first wireless communication coil at the upper end of the well-retention intelligent device.

11. A non-contact abandoned well safety monitoring method, characterized in that: The non-contact abandoned well safety monitoring method adopts the non-contact abandoned well safety monitoring system according to claim 1, comprising: Step 1: Connect the lower part of the well-retaining intelligent device to multiple downhole sensors through cables at the wellhead to test the changes in physical parameters of the lower part of the cement plug; Step 2, the well-retaining intelligent device is solidified in the wellbore together with the cement plug, the opening of the well-retaining intelligent device is upward, and it is located on the upper part of the uppermost cement plug; multiple downhole sensors connected to the well-retaining intelligent device are sequentially located in the lower space of each level of cement plug; the number of sensors is the same as the number of cement plugs; Step 3, when it is necessary to test the physical parameters of the lower part of the cement plug, connect the downhole tester through a cable from the wellhead, lower the downhole tester into the well, and conduct two-way communication with the well intelligent device through electromagnetic waves to test the physical parameters of the lower part of the cement plug; Step 4: After the test is completed, pull the cable and lift the downhole tester out of the wellhead.

12. The non-contact abandoned well safety monitoring system according to claim 11, characterized in that: In step 3, the downhole tester also supplies power to the well-retaining intelligent device through electromagnetic waves.

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