Electromagnetic induction detection instrument for plastic zone around well

Abstract

The invention provides an electromagnetic induction detection instrument for a plastic zone around a well. The electromagnetic induction detection instrument comprises a transmitting module, a receiving module, a probe supporting frame, a data transmission and communication module, a positioning module, a power module and an instrument shell. The instrument mainly works based on the electromagnetic induction principle, an alternating magnetic field is generated through the transmitting module, the magnetic field is spread in a stratum around a well, and when the magnetic field encounters a plastic deformation area, the electromagnetic property of the stratum can change, so that a secondary magnetic field is generated; and after the receiving module receives the secondary magnetic field signal, the signal is subjected to a series of processing, so that the relevant information of the plastic zone around the well can be determined. The instrument has the advantages of high efficiency, accuracy, real-time performance and the like, and can provide technical support for the fields of oil and gas development, underground engineering construction and the like.

Description

Technical Field

[0001] The present invention relates to the fields of oil and gas development, underground engineering construction, and engineering detection technologies. Specifically, it relates to an electromagnetic induction detection instrument for the plastic zone around a well, which is used to detect the plastic deformation area of the formation around the well and can provide technical support for fields such as oil and gas development and underground engineering construction. Background Art

[0002] During the development of oil and gas fields, operations such as drilling and well completion will disturb the formation around the well, resulting in the emergence of plastic deformation areas in the formation. The existence of these plastic zones will affect the stability of the wellbore, increase the risks of wellbore collapse and casing damage, and thus affect the normal production and lifespan of oil and gas wells. In underground engineering construction, such as subway tunnels and deep foundation pit excavations, it will also disturb the surrounding formation and form plastic zones, posing a threat to the safety and stability of the project.

[0003] Currently, the methods for detecting the plastic zone around a well mainly include core drilling, acoustic logging, etc., but these methods have some deficiencies. Core drilling is costly, inefficient, and can only obtain information on local formations; acoustic logging is greatly affected by factors such as formation porosity and fluid properties, and the accuracy of the detection results needs to be improved. Therefore, an efficient, accurate, and real-time detection instrument for the plastic zone around a well is needed. Summary of the Invention

[0004] The purpose of the present invention is to provide an electromagnetic induction detection instrument for the plastic zone around a well, which can efficiently, accurately, and real-time detect the plastic deformation area of the formation around the well and provide technical support for fields such as oil and gas development and underground engineering construction.

[0005] The technical solution of the present invention is: an electromagnetic induction detection instrument for the plastic zone around a well, including a transmitting module, a receiving module, a probe support frame, a data transmission and communication module, a positioning module, a power supply module, and an instrument housing.

[0006] 1. Transmitting module:

[0007] (1) Transmitting coil

[0008] Structure and material: The transmitting coil is a hollow solenoid structure wound with multi-turn copper enameled wire. The enameled wire has good insulation performance to prevent inter-turn short circuits. Copper enameled wire is selected because copper has high electrical conductivity, which can effectively reduce resistance loss and improve electromagnetic conversion efficiency.

[0009] Size parameters: Its outer diameter is designed according to the wellbore size, generally between 50 and 200 mm. For example, in oil and gas wells with a smaller diameter, a transmitting coil with an outer diameter of 50 - 100 mm can be selected; while in large underground engineering boreholes, a coil with an outer diameter of 150 - 200 mm can be chosen. The number of turns is 100 - 500 turns. More turns can enhance the magnetic field strength, but it will also increase the resistance and inductance of the coil, which needs to be comprehensively considered during the design.

[0010] Function: When an alternating current passes through the transmitting coil, an alternating magnetic field will be generated, and this magnetic field will propagate to the formation around the well, providing an initial magnetic field for subsequent electromagnetic induction detection.

[0011] Adopting magnetic field focusing technology: Add a magnetic lens, a magnetic field focusing element, around the transmitting coil to direct the magnetic field more concentratedly to the formation around the well; the magnetic lens can help reduce the diffusion and attenuation of the magnetic field when passing through the instrument housing.

[0012] (2) Transmitting circuit

[0013] The transmitting circuit is connected to the transmitting coil and is used to provide an alternating current for the transmitting coil. The transmitting circuit includes a signal generator, a power amplifier, and a matching circuit.

[0014] Signal generator: It can generate a sine wave signal with a specific frequency, and the frequency range is 1 - 10 kHz. Different formation conditions and detection requirements may require different frequencies. Lower frequencies can penetrate deeper formations, but the resolution is relatively low; higher frequencies have higher resolution, but the penetration depth is limited. For example, when detecting the plastic zone in shallow formations, a frequency of 5 - 10 kHz can be selected; while when detecting deep formations, a frequency of 1 - 3 kHz can be chosen.

[0015] Power amplifier: Amplify the weak signal generated by the signal generator to sufficient power, generally between 10 and 100 W. The power amplifier needs to have good linearity and stability to ensure that the amplified signal is not distorted. For example, when the signal power generated by the signal generator is 10 mW, after being amplified by the power amplifier, the output power can reach 50 W.

[0016] Matching circuit: It is used to achieve impedance matching between the transmitting circuit and the transmitting coil. Since the transmitting coil has certain inductance and resistance, its impedance may not match the output impedance of the transmitting circuit, which will lead to a reduction in energy transfer efficiency. The matching circuit can adjust the circuit parameters to make the output impedance of the transmitting circuit match the impedance of the transmitting coil, thereby improving the energy transfer efficiency and converting more electrical energy into magnetic field energy.

[0017] (3) Transmitting module housing

[0018] Material: The housing of the transmitting module is made of high-strength and corrosion-resistant engineering plastic, glass fiber-reinforced polyamide (PA66-GT30), which is used to protect the transmitting coil and the transmitting circuit. Glass fiber-reinforced polyamide (PA66-GT30) has good mechanical properties and chemical stability, and can withstand the harsh downhole environmental conditions.

[0019] Structure: The housing of the transmitting module is cylindrical, and sealed end caps are provided at both ends. The sealed end caps are made of fluororubber (FKM), which has good waterproof, dustproof, corrosion-resistant and sealing properties, and can effectively prevent moisture, dust, etc. from entering the interior of the transmitting module to protect the transmitting coil and the transmitting circuit. PTFE filler is added to fluororubber (FKM) to improve its compressive resistance and wear resistance.

[0020] Installation method: The housing of the transmitting module is installed on the probe support frame through taper thread connection. The thread connection has high connection strength and sealing performance, and the thread surface is treated with PTFE coating to reduce friction corrosion.

[0021] 2. Receiving module:

[0022] (1) Receiving coil

[0023] Structure and material: It is also a hollow solenoid wound with multi-turn copper enameled wire, and is arranged coaxially with the transmitting coil.

[0024] Dimension parameters: Its outer diameter is the same as that of the transmitting coil, and the number of turns is 50 - 300 turns. The number of turns and dimensions of the receiving coil need to be matched according to the parameters of the transmitting coil and the requirements of detection sensitivity.

[0025] Function: It is used to receive the secondary magnetic field signal generated by electromagnetic induction in the formation around the well. When the alternating magnetic field generated by the transmitting coil encounters the plastic deformation area of the formation around the well, the electromagnetic characteristics of the formation will change, thereby generating a secondary magnetic field, and the receiving coil can sense this secondary magnetic field and convert it into an electrical signal.

[0026] (2) Receiving circuit

[0027] The receiving circuit is connected to the receiving coil and is used to amplify, filter and process the received secondary magnetic field signal. The receiving circuit includes a preamplifier, a band-pass filter, an analog-to-digital converter and a signal processor.

[0028] Preamplifier: Amplify the received weak secondary magnetic field signal by 10 - 100 times. Since the secondary magnetic field signal is very weak, the preamplifier has the characteristics of high gain and low noise to improve the signal-to-noise ratio.

[0029] Band - pass filter: It is used to filter out noise interference and only allow signals within a specific frequency range to pass through. The frequency range of the band - pass filter matches that of the transmitted signal. For example, if the frequency of the transmitted signal is 5 kHz, the frequency range of the band - pass filter can be set to 4.5 - 5.5 kHz, thereby effectively filtering out noise signals of other frequencies.

[0030] Analog - to - digital converter: It converts analog signals into digital signals. The resolution and sampling rate of the analog - to - digital converter affect the accuracy and real - time performance of the signals. Higher resolution can improve the accuracy of the signals, and higher sampling rate can ensure the real - time performance of the signals.

[0031] Signal processor: It analyzes and processes digital signals to extract information related to the plastic zone around the wellbore. It uses a digital signal processor (DSP) and processes the signals through specific algorithms such as spectral analysis and feature extraction, thereby determining whether there is a plastic deformation zone around the wellbore and the location and extent of the plastic zone.

[0032] (3) Receiver module housing

[0033] Material and structure: It has the same material and structure as the transmitter module housing, is made of high - strength and corrosion - resistant engineering plastics, and is used to protect the receiving coil and receiving circuit; the receiver module housing is cylindrical with sealed end caps at both ends.

[0034] Installation method: It is installed on the probe support frame through tapered threads, keeping a certain distance from the transmitter module housing to avoid mutual interference; the thread surface is treated with PTFE coating to reduce frictional corrosion.

[0035] 3. Probe support frame:

[0036] Material: It is made of high - strength and lightweight aluminum alloy material. Aluminum alloy has the advantages of low density, high strength, and corrosion resistance, which can reduce the weight of the instrument while ensuring the strength of the probe support frame, improving portability and installation efficiency.

[0037] Structure: It is installed at the bottom of the instrument, has a rail structure, and has good support and stability. The transmitter module and receiver module can slide along the rail to the appropriate position and then be fixed.

[0038] Function: It is used to support the transmitter module and receiver module, and can adjust the installation positions of the transmitter module and receiver module according to actual needs to ensure the detection effect. For example, under different wellbore conditions, it may be necessary to adjust the distance and angle between the transmitter module and the receiver module to obtain the best detection signal.

[0039] 4. Data transmission and communication module:

[0040] The data transmission and communication module is installed in the installation cavity of the instrument, and it includes a wireless communication module and a wired communication interface.

[0041] The wireless communication module adopts wireless communication technologies such as low-power LoRa and WIA-PA, and is used to transmit the processed detection data to the ground monitoring terminal in real time; adopting industrial-grade standards, it has the characteristics of strong anti-interference ability and long transmission distance; during the transmission process, the wireless communication module will automatically encode and encrypt the data to ensure the security and integrity of the data.

[0042] The wired communication interface adopts a fiber optic interface and is used for data interaction with other downhole devices or for wired data transmission when necessary.

[0043] 5. Positioning module: Installed in the installation cavity of the instrument and connected to the receiving module. Adopting the downhole positioning technology that combines RFID and WSN, it can determine the position of the instrument in the well in real time and transmit the position information to the receiving module, so as to more accurately analyze the information of the plastic area at different positions on the wellbore.

[0044] 6. Power module:

[0045] (1) Power supply design

[0046] The power module is installed in the installation cavity of the instrument and connected to other corresponding components. The power module adopts a portable and detachable rechargeable high-energy density lithium battery pack. The lithium battery has the advantages of large capacity, small volume, and light weight, and can provide stable power supply for the instrument. The power module supports large capacity and energy-saving modes to ensure that the instrument can work stably for a long time.

[0047] The power module has good heat dissipation, waterproof and dustproof functions, ensuring that the power module can still maintain stability and durability in the harsh downhole environment.

[0048] (2) Circuit design of the power module

[0049] An intelligent protection circuit is provided, which has functions such as overcharge protection, over-discharge protection, and short-circuit protection to ensure the safety of the power module during use.

[0050] A battery power monitoring circuit is provided, which can monitor the battery power in real time. By detecting parameters such as the voltage and current of the battery to judge the remaining battery power, an alarm signal will be triggered when the power is lower than the set value to remind the staff to charge in time.

[0051] 7. Instrument shell:

[0052] Material: The instrument shell is cylindrical and made of high-strength corrosion-resistant non-magnetic nickel-based alloy, with good sealing performance and mechanical strength. The inside is filled with shock-absorbing materials, which can effectively protect the internal components from the harsh downhole environment.

[0053] Structure: Inside the instrument housing, there is an installation cavity for installing and fixing components such as the data transmission and communication module, positioning module, and power module; on the outside, there are interfaces for easy installation and maintenance, and a stone mill mechanical seal ring and a quick locking mechanism are adopted.

[0054] The present invention has the following beneficial effects:

[0055] High efficiency: The detection speed is fast, and it can complete the detection of the formation around the well in a large range in a short time.

[0056] Accuracy: Utilizing the principle of electromagnetic induction, it is not affected by factors such as porosity and fluid properties, and the detection results are accurate and reliable.

[0057] Real-time performance: It can detect the plastic deformation area of the formation around the well in real time, and provide a basis for engineering decision-making in a timely manner.

[0058] Non-destructive: There is no need to perform destructive operations such as drilling and coring on the wellbore, reducing damage to the wellbore.

[0059] Convenient operation: The instrument adopts a modular design, with a simple structure, clear connections between modules, facilitating installation; the modules are relatively independent of each other, easy to maintain and upgrade; and the usage method is simple. Description of the drawings

[0060] Figure 1 It is a schematic diagram of the overall structure of the instrument in Embodiment 1 of the present invention.

[0061] Reference numerals:

[0062] In the figure, 1 is the transmitting module, 2 is the receiving module, 3 is the probe support frame, 4 is the data transmission and communication module, 5 is the positioning module, 6 is the power module, and 7 is the instrument housing. Specific embodiments

[0063] In addition, the specific details disclosed below are only for the purpose of illustration and easy understanding, rather than limitation. The following details do not limit that the present invention must be implemented with the following specific details. The basic concept of the present invention is described below in conjunction with specific embodiments. However, it should be noted that the advantages, benefits, effects, etc. mentioned in the present invention are only examples and not limitations, and it cannot be considered that these advantages and effects are essential for each embodiment of the present invention.

[0064] It should be noted that in the present invention, unless otherwise clearly defined and limited, terms such as "installation", "connection", "coupling", "design", etc. should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components or the interaction relationship between two components. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0065] Unless otherwise defined, all technical and scientific terms used in the present invention have the same meanings as those commonly understood by those skilled in the technical field to which the present invention belongs. The terms used in the description of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0066] It should also be noted that the provided drawings only illustrate the basic concept of the present invention in a schematic manner. Only the components related to the present invention are shown in the drawings, rather than being drawn according to the number, shape, and size of the components in actual implementation. The types, quantities, and proportions of the components in actual implementation can be changed arbitrarily, and the component layout type may also be more complex.

[0067] The following will clearly and completely describe the specific implementation manners of the present invention in combination with embodiments and drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments.

[0068] Embodiment 1

[0069] An electromagnetic induction detection instrument for the plastic zone around a well includes a transmitting module, a receiving module, a probe support frame, a data transmission and communication module, a positioning module, a power supply module, and an instrument housing.

[0070] 1. Transmitting module:

[0071] (1) Transmitting coil

[0072] Structure and material: The transmitting coil is a hollow solenoid structure wound with multi-turn copper enameled wire. The enameled wire has good insulation performance to prevent short circuits between turns. Copper enameled wire is selected because copper has high electrical conductivity, which can effectively reduce resistance loss and improve electromagnetic conversion efficiency.

[0073] Size parameters: Its outer diameter is designed according to the wellbore size, generally between 50 and 200 mm. For example, in oil and gas wells with a smaller diameter, a transmitting coil with an outer diameter of 50 - 100 mm can be selected; while in large underground engineering boreholes, a coil with an outer diameter of 150 - 200 mm can be chosen. The number of turns is 100 - 500 turns. More turns can enhance the magnetic field strength, but it will also increase the resistance and inductance of the coil, which needs to be comprehensively considered during design.

[0074] Function: When an alternating current passes through the transmitting coil, an alternating magnetic field will be generated, and this magnetic field will propagate to the formation around the well, providing an initial magnetic field for subsequent electromagnetic induction detection.

[0075] Adopting magnetic field focusing technology: Add a magnetic lens, a magnetic field focusing element, around the transmitting coil to direct the magnetic field more concentratedly to the formation around the well; the magnetic lens can help reduce the diffusion and attenuation of the magnetic field when passing through the instrument housing.

[0076] (2) Transmitting circuit

[0077] The transmitting circuit is connected to the transmitting coil and is used to provide an alternating current for the transmitting coil. The transmitting circuit includes a signal generator, a power amplifier, and a matching circuit.

[0078] Signal generator: It can generate a sine wave signal with a specific frequency, and the frequency range is 1 - 10 kHz. Different formation conditions and detection requirements may require different frequencies. Lower frequencies can penetrate deeper formations, but the resolution is relatively low; higher frequencies have higher resolution, but the penetration depth is limited. For example, when detecting the plastic zone in shallow formations, a frequency of 5 - 10 kHz can be selected; while when detecting deep formations, a frequency of 1 - 3 kHz can be chosen.

[0079] Power amplifier: Amplify the weak signal generated by the signal generator to sufficient power, generally between 10 and 100 W. The power amplifier needs to have good linearity and stability to ensure that the amplified signal is not distorted. For example, when the signal power generated by the signal generator is 10 mW, after being amplified by the power amplifier, the output power can reach 50 W.

[0080] Matching circuit: It is used to achieve impedance matching between the transmitting circuit and the transmitting coil. Since the transmitting coil has a certain inductance and resistance, its impedance may not match the output impedance of the transmitting circuit, which will lead to a reduction in energy transfer efficiency. The matching circuit can adjust the circuit parameters to make the output impedance of the transmitting circuit match the impedance of the transmitting coil, thereby improving the energy transfer efficiency and converting more electrical energy into magnetic field energy.

[0081] (3) Transmitting module housing

[0082] Material: The housing of the transmitting module is made of high-strength and corrosion-resistant engineering plastic, glass fiber-reinforced polyamide (PA66-GT30), which is used to protect the transmitting coil and the transmitting circuit. Glass fiber-reinforced polyamide (PA66-GT30) has good mechanical properties and chemical stability, and can withstand the harsh downhole environmental conditions.

[0083] Structure: The housing of the transmitting module is cylindrical, with sealed end caps at both ends. The sealed end caps are made of fluororubber (FKM), which has good waterproof, dustproof, corrosion-resistant and sealing properties, and can effectively prevent moisture, dust, etc. from entering the inside of the transmitting module to protect the transmitting coil and the transmitting circuit. PTFE filler is added to fluororubber (FKM) to improve its compressive resistance and wear resistance.

[0084] Installation method: The housing of the transmitting module is installed on the probe support frame through taper thread connection. The thread connection has high connection strength and sealing performance, and the thread surface is treated with PTFE coating to reduce friction corrosion.

[0085] 2. Receiving module:

[0086] (1) Receiving coil

[0087] Structure and material: It is also a hollow solenoid wound with multi-turn copper enameled wire and arranged coaxially with the transmitting coil.

[0088] Dimension parameters: Its outer diameter is the same as that of the transmitting coil, and the number of turns is 50 - 300 turns. The number of turns and dimensions of the receiving coil need to be matched according to the parameters of the transmitting coil and the requirements of detection sensitivity.

[0089] Function: It is used to receive the secondary magnetic field signal generated by electromagnetic induction in the formation around the wellbore. When the alternating magnetic field generated by the transmitting coil encounters the plastic deformation area of the formation around the wellbore, the electromagnetic characteristics of the formation will change, thus generating a secondary magnetic field. The receiving coil can sense this secondary magnetic field and convert it into an electrical signal.

[0090] (2) Receiving circuit

[0091] The receiving circuit is connected to the receiving coil and is used to amplify, filter and process the received secondary magnetic field signal. The receiving circuit includes a preamplifier, a band-pass filter, an analog-to-digital converter and a signal processor.

[0092] Preamplifier: Amplify the received weak secondary magnetic field signal by 10 - 100 times. Since the secondary magnetic field signal is very weak, the preamplifier has the characteristics of high gain and low noise to improve the signal-to-noise ratio of the signal.

[0093] Band - pass filter: It is used to filter out noise interference and only allow signals within a specific frequency range to pass through. The frequency range of the band - pass filter matches that of the transmitted signal. For example, if the frequency of the transmitted signal is 5 kHz, the frequency range of the band - pass filter can be set to 4.5 - 5.5 kHz, thus effectively filtering out noise signals of other frequencies.

[0094] Analog - to - digital converter: It converts analog signals into digital signals. The resolution and sampling rate of the analog - to - digital converter affect the accuracy and real - time performance of the signals. A higher resolution can improve the accuracy of the signals, and a higher sampling rate can ensure the real - time performance of the signals.

[0095] Signal processor: It analyzes and processes digital signals to extract information related to the plastic zone around the wellbore. It uses a digital signal processor (DSP) to perform spectrum analysis, feature extraction, etc. on the signals through specific algorithms, thereby determining whether there is a plastic deformation area in the formation around the wellbore and the location and extent of the plastic zone.

[0096] (3) Housing of the receiving module

[0097] Material and structure: It has the same material and structure as the housing of the transmitting module, is made of high - strength and corrosion - resistant engineering plastics, and is used to protect the receiving coil and receiving circuit; the housing of the receiving module is cylindrical, with sealed end caps at both ends.

[0098] Installation method: It is installed on the probe support frame through taper threads, and maintains a certain distance from the housing of the transmitting module to avoid mutual interference; the thread surface is treated with PTFE coating to reduce frictional corrosion.

[0099] 3. Probe support frame:

[0100] Material: It is made of high - strength and lightweight aluminum alloy material. Aluminum alloy has the advantages of low density, high strength, and corrosion resistance, which can reduce the weight of the instrument while ensuring the strength of the probe support frame, improving portability and installation efficiency.

[0101] Structure: It is installed at the bottom of the instrument, has a rail structure, and has good support and stability. The transmitting module and the receiving module can slide along the rail to the appropriate position and then be fixed.

[0102] Function: It is used to support the transmitting module and the receiving module, and can adjust the installation positions of the transmitting module and the receiving module according to actual needs to ensure the detection effect. For example, under different wellbore conditions, it may be necessary to adjust the distance and angle between the transmitting module and the receiving module to obtain the best detection signal.

[0103] 4. Data transmission and communication module:

[0104] The data transmission and communication module is installed in the installation cavity of the instrument, and it includes a wireless communication module and a wired communication interface.

[0105] The wireless communication module adopts wireless communication technologies such as low-power LoRa and WIA-PA, and is used to transmit the processed detection data to the ground monitoring terminal in real time; it adopts industrial-grade standards, and has the characteristics of strong anti-interference ability and long transmission distance; during the transmission process, the wireless communication module will automatically encode and encrypt the data to ensure the security and integrity of the data.

[0106] The wired communication interface adopts a fiber optic interface, and is used for data interaction with other downhole devices or for wired data transmission when necessary.

[0107] 5. Positioning module: Installed in the installation cavity of the instrument and connected to the receiving module. It adopts the downhole positioning technology that combines RFID and WSN, can determine the position of the instrument in the well in real time, and transmit the position information to the receiving module, so as to analyze the information of the plastic area at different positions of the wellbore more accurately.

[0108] 6. Power supply module:

[0109] (1) Power supply design

[0110] The power supply module is installed in the installation cavity of the instrument and connected to other corresponding components. The power supply module adopts a portable and detachable rechargeable high-energy density lithium battery pack. The lithium battery has the advantages of large capacity, small volume, and light weight, and can provide stable power supply for the instrument.

[0111] The power supply module supports large capacity and energy-saving modes to ensure that the instrument can work stably for a long time.

[0112] The power supply module has good heat dissipation, waterproof and dustproof functions, ensuring that the power supply module can still maintain stability and durability in the harsh downhole environment.

[0113] (2) Circuit design of the power supply module

[0114] An intelligent protection circuit is provided, which has functions such as overcharge protection, over-discharge protection, and short-circuit protection to ensure the safety of the power supply during use.

[0115] A battery power monitoring circuit is provided, which can monitor the battery power in real time. It judges the remaining battery power by detecting parameters such as the voltage and current of the battery. When the power is lower than the set value, an alarm signal will be triggered to remind the staff to charge in time.

[0116] 7. Instrument housing:

[0117] Material: The instrument housing is cylindrical and made of high-strength corrosion-resistant non-magnetic nickel-based alloy, with good sealing performance and mechanical strength. The interior is filled with shock-absorbing materials, which can effectively protect the internal components from the harsh downhole environment.

[0118] Structure: Inside the instrument housing, there is an installation cavity for installing and fixing components such as data transmission and communication modules, positioning modules, and power modules; on the outside, there are interfaces for easy installation and maintenance, using graphite mechanical seal rings and quick-locking mechanisms.

[0119] Overview of the assembly process of the instrument of the present invention:

[0120] After winding the transmitting coil, connect it to the transmitting circuit, and encapsulate the transmitting circuit in the transmitting module housing, and seal it with a sealing end cover.

[0121] After winding the receiving coil, connect it to the receiving circuit, and encapsulate the receiving circuit in the receiving module housing, and seal it with a sealing end cover.

[0122] Install the transmitting module and the receiving module on the probe support frame through taper thread connection, and adjust the spacing and position between the transmitting module and the receiving module.

[0123] Install the probe support frame in the installation cavity of the instrument through high-strength corrosion-resistant pin shafts.

[0124] Install the data transmission and communication module, positioning module, and power module in the corresponding installation cavities of the instrument, and connect the connecting wires between the modules.

[0125] Overview of the usage method of the instrument of the present invention:

[0126] Preparation before detection: Before putting the instrument into the well for detection, the staff needs to conduct a comprehensive inspection of the instrument to ensure that it can work properly. Check whether each component of the instrument is damaged and whether it can work normally; check whether the power of the power module is sufficient. If the power is insufficient, replace the battery in time or use the supporting charger to charge; check whether the connections between components such as the data transmission and communication module, receiving module, and power module are normal. After checking, establish a communication connection with the instrument through the ground monitoring terminal.

[0127] Lower the instrument: Use a special lowering device (such as a cable winch) to slowly lower the instrument into the well. During the lowering process, the staff needs to closely observe the operating status of the lowering device and the feedback signal of the instrument to ensure that the instrument can reach the predetermined detection position smoothly and accurately. At the same time, view the preliminary data transmitted back by the instrument in real time through the ground monitoring terminal to judge whether the instrument is working properly; if the data is abnormal, immediately stop lowering and check whether the instrument has a fault.

[0128] Data acquisition, transmission, and processing: After the instrument starts working, the signal generator generates a sine wave signal with a specific frequency. After being amplified by the power amplifier, it is transmitted to the transmitting coil through the matching circuit, and the transmitting coil generates an alternating magnetic field. The magnetic field propagates in the formation around the wellbore. When it encounters a plastic deformation area, the electromagnetic properties of the formation change, thereby generating a secondary magnetic field. After the receiving coil receives the secondary magnetic field signal, it transmits it to the receiving circuit. The receiving circuit amplifies, filters, and processes the signal to extract information related to the plastic zone around the wellbore.

[0129] The data transmission and communication module transmits the processed detection data to the ground monitoring terminal in real time for further processing and analysis by the staff.

[0130] Maintenance process: The maintenance of the instrument includes regular inspections, cleaning, and calibration. Regular inspections mainly check whether components such as the instrument shell, each module, and connecting wires are in good condition and whether they need to be replaced, and check the battery power to ensure the power supply of the instrument; cleaning mainly removes dirt and deposits on the surfaces of each component of the instrument to ensure the sensitivity of each component; calibration is to calibrate the instrument regularly according to the usage situation to ensure its measurement accuracy and precision.

[0131] Precautions: During use, the instrument should be comprehensively inspected regularly to ensure its normal operation; the instrument should be kept away from strong magnetic fields, high temperatures, etc. to avoid affecting the accuracy of the detection results; when installing and disassembling the instrument, careful operation should be taken to avoid damaging each component.

[0132] The working principle of the instrument of the present invention is as follows:

[0133] I. Overview of the overall principle

[0134] The instrument of the present invention mainly works based on the principle of electromagnetic induction. An alternating magnetic field is generated by the transmitting module. This magnetic field propagates in the formation around the wellbore. When it encounters a plastic deformation area, the electromagnetic properties of the formation change, thereby generating a secondary magnetic field. After the receiving module receives this secondary magnetic field signal, through a series of processing and analysis, the information related to the plastic zone around the wellbore can be determined.

[0135] II. Detailed principle description

[0136] (1) The transmitting module generates an alternating magnetic field

[0137] Signal generation: The signal generator in the transmitting circuit generates a sine wave signal with a specific frequency (1 - 10 kHz). The selection of this frequency is determined according to the characteristics of the formation around the wellbore and the detection requirements. Lower frequencies can penetrate deeper formations, but the resolution is relatively low; higher frequencies have higher resolution, but the penetration depth is limited.

[0138] For example, when detecting the plastic zone of shallow strata, a frequency of 5 - 10 kHz can be selected; while when detecting deep strata, a frequency of 1 - 3 kHz can be selected.

[0139] Signal amplification and matching: The power amplifier amplifies the weak signal generated by the signal generator to sufficient power (10 - 100 W). Since the transmitting coil requires a certain amount of power to generate a magnetic field with sufficient intensity to penetrate the formation around the well and be effectively received by the receiving module.

[0140] The matching circuit is used to achieve impedance matching between the transmitting circuit and the transmitting coil. Since the transmitting coil has a certain inductance and resistance, its impedance may not match the output impedance of the transmitting circuit, which will lead to a decrease in the energy transfer efficiency. The matching circuit can adjust the circuit parameters to make the output impedance of the transmitting circuit match the impedance of the transmitting coil, thereby improving the energy transfer efficiency and converting more electrical energy into magnetic field energy.

[0141] Alternating magnetic field generation: The amplified signal passes through the transmitting coil, which is a hollow solenoid wound with a multi - turn copper enameled wire. When an alternating current passes through the transmitting coil, according to Ampere's circuital law, an alternating magnetic field will be generated around it. This alternating magnetic field propagates towards the formation around the well with the transmitting coil as the center.

[0142] (2) Propagation of the alternating magnetic field in the formation around the well and generation of the secondary magnetic field

[0143] Response of normal formation: In a normal elastic formation, the electromagnetic properties of the formation are relatively stable. During the propagation of the alternating magnetic field, it will induce an electric current in the formation. However, due to the uniformity and elasticity of the formation, the distribution and change of the induced current are relatively regular, and the generated secondary magnetic field is relatively weak and stable.

[0144] Response of the plastic deformation area: When the alternating magnetic field encounters the plastic deformation area of the formation around the well, the situation will change. Plastic deformation will cause changes in the pore structure, particle arrangement, etc. of the formation, thereby changing the electromagnetic properties (such as conductivity, permeability) of the formation.

[0145] This change in electromagnetic properties will make the distribution and change of the induced current in the formation no longer regular, thereby generating a stronger secondary magnetic field. The intensity and distribution characteristics of the secondary magnetic field are related to factors such as the location, scope, and degree of deformation of the plastic deformation area.

[0146] (3) Receiving and processing the secondary magnetic field signal by the receiving module

[0147] Signal reception: The receiving coil is arranged coaxially with the transmitting coil, and it is also a hollow solenoid wound with a multi - turn copper enameled wire. The receiving coil can sense the secondary magnetic field generated by electromagnetic induction in the formation around the well and convert it into an electrical signal.

[0148] Since the secondary magnetic field signal is very weak, the electrical signal received by the receiving coil is also very weak and needs to be amplified by a preamplifier. The preamplifier amplifies the signal by 10 to 100 times to improve the signal-to-noise ratio of the signal.

[0149] Signal filtering: The amplified signal may contain various noise interferences. In order to extract the useful secondary magnetic field signal, a band-pass filter is needed for filtering. The frequency range of the band-pass filter matches the frequency range of the transmitted signal, allowing only signals within a specific frequency range to pass through, thereby filtering out noise signals of other frequencies.

[0150] Signal digitization: The filtered analog signal is converted into a digital signal by an analog-to-digital converter. The resolution and sampling rate of the analog-to-digital converter will affect the accuracy and real-time performance of the signal. A higher resolution can improve the accuracy of the signal, and a higher sampling rate can ensure the real-time performance of the signal.

[0151] Signal analysis and processing: The signal processor analyzes and processes the digital signal. It uses a digital signal processor (DSP) to perform spectrum analysis, feature extraction, etc. on the signal through specific algorithms. For example, by analyzing features such as the frequency components and amplitude changes of the signal, it is determined whether there is a plastic deformation area around the well and the location and scope of the plastic zone.

[0152] (4) Data transmission and result presentation

[0153] Data transmission: The data transmission and communication module transmits the processed detection data to the ground monitoring terminal in real time.

[0154] Result presentation: After receiving the detection data, the ground monitoring terminal can further process and analyze the data through professional data processing and analysis software, and present the detection results in the form of intuitive graphs, reports, etc. Staff can understand the distribution of the plastic zone around the well based on these results, providing technical support for oil and gas development and underground engineering construction, etc.

[0155] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. An electromagnetic induction detection instrument for the plastic zone around a well, comprising a transmitting module, a receiving module, a probe support frame, a data transmission and communication module, a positioning module, a power module, and an instrument housing.

2. The apparatus according to claim 1, characterized in that The transmitting module includes a transmitting coil, a transmitting circuit, and a transmitting module housing; The structure and material of the transmitting coil: a hollow solenoid structure formed by winding multiple turns of copper enameled wire; the enameled wire has good insulation performance and can prevent short circuits between turns; copper enameled wire is selected because copper has high conductivity, which can effectively reduce resistance loss and improve electromagnetic conversion efficiency; The dimensional parameters of the transmitting coil are as follows: its outer diameter is designed according to the borehole size, generally between 50 and 200 mm; the number of turns is 100 to 500 turns; The function of the transmitting coil is as follows: when an alternating current passes through the transmitting coil, an alternating magnetic field is generated, and the magnetic field propagates to the formation around the well, providing an initial magnetic field for subsequent electromagnetic induction detection; The transmitting coil adopts a magnetic field focusing technology: a magnetic field focusing element, a magnetic lens, is added around the transmitting coil to direct the magnetic field more concentratedly toward the formation around the well; the magnetic lens can help reduce the diffusion and attenuation of the magnetic field when passing through the instrument housing; The transmitting circuit is connected to the transmitting coil and is used to provide an alternating current to the transmitting coil. The transmitting circuit includes a signal generator, a power amplifier and a matching circuit. The signal generator can generate a sine wave signal of a specific frequency, with a frequency range of 1 to 10 kHz. Different formation conditions and detection requirements may require different frequencies. A lower frequency can penetrate deeper formations, but the resolution is relatively low; a higher frequency has a higher resolution, but the penetration depth is limited. For example, when detecting the plastic zone of a shallow formation, a frequency of 5 to 10 kHz can be selected; and when detecting a deep formation, a frequency of 1 to 3 kHz can be selected. The power amplifier amplifies the weak signal generated by the signal generator to a sufficient power, generally between 10 and 100W; the power amplifier needs to have good linearity and stability to ensure that the amplified signal is not distorted; for example, when the signal power generated by the signal generator is 10mW, after amplification by the power amplifier, the output power can reach 50W; The matching circuit is used to achieve impedance matching between the transmitting circuit and the transmitting coil. Since the transmitting coil has a certain inductance and resistance, its impedance may not match the output impedance of the transmitting circuit, which will lead to reduced energy transmission efficiency. The matching circuit can adjust the circuit parameters to match the output impedance of the transmitting circuit with the impedance of the transmitting coil, thereby improving the energy transmission efficiency and converting more electrical energy into magnetic field energy. The transmitting module housing is made of high-strength and corrosion-resistant engineering plastic glass fiber reinforced polyamide (PA66-GT30) to protect the transmitting coil and transmitting circuit; Glass fiber reinforced polyamide (PA66-GT30) has good mechanical properties and chemical stability, and can withstand the harsh environmental conditions underground; The transmitting module housing is cylindrical, with sealed end caps at both ends; the sealed end caps are made of fluororubber (FKM), which has good waterproof, dustproof, corrosion-resistant and sealing properties, and can effectively prevent moisture, dust, etc. from entering the interior of the transmitting module, protecting the transmitting coil and transmitting circuit; PTFE filler is added to the fluororubber (FKM) to improve pressure resistance and wear resistance; The transmitting module housing is mounted on the probe support frame through a tapered thread connection; the thread connection has high connection strength and sealing performance, and the thread surface is PTFE-plated to reduce friction corrosion.

3. The apparatus according to claim 1, characterized in that The receiving module includes a receiving coil, a receiving circuit, and a receiving module housing; The structure and material of the receiving coil: a hollow solenoid made of multiple turns of copper enameled wire, coaxially arranged with the transmitting coil; The size parameters of the receiving coil: its outer diameter is the same as that of the transmitting coil, and the number of turns is 50 to 300 turns; the number of turns and size design of the receiving coil need to be matched according to the parameters of the transmitting coil and the detection sensitivity requirements; The receiving coil is used to receive the secondary magnetic field signal generated by electromagnetic induction in the formation around the well. When the alternating magnetic field generated by the transmitting coil encounters the plastic deformation area of ​​the formation around the well, the electromagnetic characteristics of the formation will change, thereby generating a secondary magnetic field. The receiving coil can sense this secondary magnetic field and convert it into an electrical signal. The receiving circuit is connected to the receiving coil and is used to amplify, filter and process the received secondary magnetic field signal; the receiving circuit includes a preamplifier, a bandpass filter, an analog-to-digital converter and a signal processor; The preamplifier amplifies the received weak secondary magnetic field signal by 10 to 100 times; since the secondary magnetic field signal is very weak, the preamplifier has the characteristics of high gain and low noise to improve the signal-to-noise ratio; The bandpass filter is used to filter out noise interference and only allow signals in a specific frequency range to pass through; the frequency range of the bandpass filter matches the frequency range of the transmitted signal. For example, if the frequency of the transmitted signal is 5kHz, the frequency range of the bandpass filter can be set to 4.5-5.5kHz, thereby effectively filtering out noise signals of other frequencies; The analog-to-digital converter converts analog signals into digital signals. The resolution and sampling rate of the analog-to-digital converter will affect the accuracy and real-time performance of the signal. A higher resolution can improve the accuracy of the signal, and a higher sampling rate can ensure the real-time performance of the signal. The signal processor: analyzes and processes the digital signal to extract information related to the plastic zone around the well; it uses a digital signal processor (DSP) to perform spectrum analysis, feature extraction and other processing on the signal through a specific algorithm, so as to determine whether there is a plastic deformation area in the formation around the well and the location and range of the plastic zone; The receiving module housing is made of the same material and structure as the transmitting module housing, and is made of high-strength and corrosion-resistant engineering plastic glass fiber reinforced polyamide (PA66-GT30), which is used to protect the receiving coil and receiving circuit; the receiving module housing is cylindrical, and sealed end caps are provided at both ends; the receiving module housing is installed on the probe support frame through a tapered thread connection, and a certain distance is maintained with the transmitting module housing to avoid mutual interference; The thread surface is PTFE-plated to reduce friction corrosion.

4. The apparatus according to claim 1, characterized in that The probe support frame is made of high-strength and lightweight aluminum alloy material; aluminum alloy has the advantages of low density, high strength, and corrosion resistance, and can reduce the weight of the instrument while ensuring the strength of the probe support frame, thereby improving portability and installation efficiency; The probe support frame is installed at the bottom of the instrument and has a guide rail structure, which has good support and stability; The transmitting module and the receiving module can be slid along the guide rail to a suitable position and then fixed; The probe support frame is used to support the transmitting module and the receiving module, and the installation positions of the transmitting module and the receiving module can be adjusted according to actual needs to ensure the detection effect; for example, under different wellbore conditions, it may be necessary to adjust the distance and angle between the transmitting module and the receiving module to obtain the best detection signal.

5. The apparatus according to claim 1, characterized in that The data transmission and communication module is installed in the installation cavity of the instrument, and includes a wireless communication module and a wired communication interface; The wireless communication module adopts low-power LoRa, WIA-PA and other wireless communication technologies to transmit the processed detection data to the ground monitoring terminal in real time; it adopts industrial-grade standards and has the characteristics of strong anti-interference ability and long transmission distance; during the transmission process, the wireless communication module will automatically encode and encrypt the data to ensure the security and integrity of the data; The wired communication interface adopts an optical fiber interface, which is used for data interaction with other equipment underground or for wired data transmission when necessary.

6. The apparatus according to claim 1, characterized in that The positioning module is installed in the installation cavity of the instrument and connected to the receiving module; the downhole positioning technology integrating RFID and WSN is adopted to determine the position of the instrument in the downhole in real time and transmit the position information to the receiving module so as to more accurately analyze the information of the plastic areas at different positions of the well wall.

7. The apparatus according to claim 1, characterized in that The power module is installed in the installation cavity of the instrument and connected to other corresponding components; the power module adopts a portable, detachable, rechargeable, high-energy-density lithium battery pack. The lithium battery has the advantages of large capacity, small size, light weight, etc., and can provide a stable power supply for the instrument; The power module supports large capacity and energy-saving mode to ensure that the instrument can work stably and permanently; The power module has good heat dissipation, waterproof and dustproof functions, ensuring that the power module can still maintain stability and durability in the harsh environment underground; The power module is equipped with an intelligent protection circuit with functions such as overcharge protection, over-discharge protection, and short-circuit protection to ensure the safety of the power supply during use; the power module is equipped with a power monitoring circuit that can monitor the battery power in real time; the remaining power of the battery is judged by detecting the battery voltage, current and other parameters. When the power is lower than the set value, an alarm signal will be triggered to remind the staff to charge in time.

8. The apparatus according to claim 1, characterized in that The instrument housing is cylindrical and made of high-strength, corrosion-resistant, non-magnetic nickel-based alloy, with good sealing and mechanical strength. The interior is filled with shockproof materials, which can effectively protect the internal components from the harsh environment underground. The instrument housing is provided with an installation cavity inside for installing and fixing components such as data transmission and communication modules, positioning modules and power modules; the outside is provided with an interface for easy installation and maintenance, and adopts a stone-ground mechanical sealing ring and a quick locking mechanism.

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