An air flow cleaning process for oil casing cutting tools

Abstract

The present application relates to the technical field of cutting tool cleaning, and discloses an airflow cleaning process for oil casing cutting tools, which comprises the following steps: collecting a feedback back pressure sequence at the outlet of an airflow nozzle, and calculating a pressure variance parameter by intercepting a sliding window; when the pressure variance parameter is lower than a preset threshold value, it is determined that a steady-state aerodynamic boundary layer is formed on the topological wall surface of the tool, and a frequency-modulated pulse cleaning mode is triggered; a pulse airflow output valve is driven to output a pulse airflow, the pulse frequency is linearly stepped up, and the rising slope is kept in a preset range, a large gradient pressure wave is induced on the wall surface, a shedding vortex is excited, the aerodynamic boundary layer is broken, the transient shear stress exceeds the shear yield limit of the composite adhesive layer, and peeling is realized; and the present application uses back pressure variance to perceive dynamic pressure shielding, uses a steep pulse front and a high-frequency step to break the air cushion barrier, enhances the shear peeling capacity, and suppresses coking.

Description

Technical Field

[0001] This invention relates to an airflow cleaning process for oil casing cutting tools, belonging to the field of cutting tool cleaning technology. Background Technology

[0002] In deep well cutting and workover operations, tubing cutting tools are subjected to prolonged exposure to high pressure, strong shear, and cutting heat. Fine metal debris generated during cutting mixes with polymers in the drilling fluid and deposits on the tool surface, forming a composite adhesion layer with high shear yield stress and rheological viscosity. If this layer is not removed promptly during working intervals, it will gradually solidify and coke under the continuous action of cutting heat. This not only increases the cutting friction resistance of the tool edge but also exacerbates thermal wear, potentially leading to chipping or premature tool failure. Existing airflow cleaning methods typically employ continuous, steady-state high-pressure airflow. When rinsing the tool surface, due to the multi-level topological structure and complex curved surface of the cutting edge of the oil sleeve cutting tool, the airflow tends to adhere to the vicinity of the tool's topological wall and become stagnant, causing local dynamic pressure to accumulate continuously, thus forming a steady-state aerodynamic boundary layer. This steady-state aerodynamic boundary layer will produce a significant dynamic pressure shielding effect, hindering the kinetic energy of subsequent airflow from entering the deep grooves of the tool, and significantly weakening the airflow shearing effect in the topological depression area. Therefore, continuous steady-state airflow can usually only carry away loose particles on the surface, and it is difficult to destroy the composite adhesion layer formed by polymer and metal debris, and it is also difficult to remove it from the deep depression.

[0003] To improve cleaning effectiveness, current methods typically involve increasing the air supply pressure or airflow velocity. However, this approach does not address the fundamental problem of dynamic pressure shielding caused by the steady-state aerodynamic boundary layer. As the air supply pressure continues to rise, the air layer adhering to and remaining near the wall actually thickens further, exacerbating the dynamic pressure shielding in the topological depression region. This not only increases gas consumption but also causes airflow energy loss, making it difficult to remove the composite adhesion layer and preventing its continued solidification and coking under cutting heat. Although existing technologies attempt to eliminate aerodynamic shielding by improving the nozzle structure or adding pulse valves, limitations also exist in airflow modulation and control methods. For example, [the following is an example from patent announcement number CN114789167]. Chinese invention patent B discloses a particle removal device and method, which uses a mover to rotate in the stator cavity to open and close the air passage to generate mechanical pulse airflow. However, this scheme is based on the preset dry dust removal of an idealized flat surface and adopts open-loop pulse control with a fixed opening and closing cycle. When applied to oil casing cutting tools with complex three-dimensional topology and deep grooves, the open-loop air pulse cannot sense the formation and evolution of the aerodynamic boundary layer on the tool wall in real time. It is difficult to adaptively adjust the slope of the pulse rise edge and the frequency step amplitude. As a result, the pulse airflow energy is easily absorbed and canceled by the stagnant air cushion at the topological depression. It is impossible to induce a large gradient pressure wave sufficient to break the steady-state aerodynamic boundary layer, and it is still difficult to peel off the composite adhesion layer with high rheological viscosity.

[0004] Therefore, how to promptly determine whether dynamic pressure shielding occurs on the tool topological wall and effectively disrupt the steady-state aerodynamic boundary layer in order to remove the highly viscous composite adhesion layer remains a problem that needs to be solved by existing technologies. Summary of the Invention

[0005] To address the problems in the background art, the technical solution of the present invention is as follows: an airflow cleaning process for oil casing cutting tools, comprising the following steps:

[0006] Step S1: Continuously acquire the feedback back pressure sequence located at the outlet of the airflow nozzle at a preset sampling frequency;

[0007] Step S2: Real-time capture of a preset number of continuous back pressure sampling points to form a sliding time window; calculate the pressure variance parameter of the back pressure sampling points within the sliding time window; use the pressure variance parameter as an objective characterization parameter for determining whether a steady-state aerodynamic boundary layer is formed on the topological wall of the oil casing cutting tool.

[0008] Step S3: Compare the pressure variance parameter with the preset pressure variance threshold.

[0009] Step S4: When the pressure variance parameter is greater than or equal to the preset pressure variance threshold, it is determined that the topological wall of the oil casing cutting tool is in a turbulent stripping state, and the initial air supply parameters are maintained; when the pressure variance parameter is lower than the preset pressure variance threshold, it is determined that the topological wall of the oil casing cutting tool forms a steady-state aerodynamic boundary layer that generates a dynamic pressure shielding effect, and the frequency modulation pulse cleaning mode is triggered.

[0010] Step S5: In the frequency modulation pulse cleaning mode, the airflow pulse modulation valve on the air supply pipeline is driven to adjust the duty cycle and output a pulse airflow with a set air supply pressure, a set gas temperature and a set target distance. The pulse frequency of the pulse airflow is controlled to increase linearly from the initial frequency to a high-frequency pulse, and the pulse rise edge slope of the pulse airflow is kept within the preset slope range. The pulse rise edge slope is used to induce a large gradient pressure wave on the topological wall of the casing cutting tool, which excites the shedding vortex, forcibly entrains and extracts the steady fluid trapped in the topological depression area to break the steady aerodynamic boundary layer, so that the transient shear stress on the wall exceeds the shear yield limit of the composite adhesion layer on the surface of the casing cutting tool, and completes the physical peeling of the composite adhesion layer.

[0011] Preferably, in step S5, the pulsed airflow output by the airflow pulse modulation valve meets the following process conditions: the supply pressure of the pulsed airflow is 3.5MPa to 5.5MPa, the gas temperature is 65°C to 85°C, and the target distance between the airflow nozzle outlet and the surface of the oil casing cutting tool is maintained at 15mm to 25mm. By maintaining the gas temperature of the pulsed airflow in the range of 65°C to 85°C, the rheological viscosity of the polymer in the composite adhesion layer is reduced. Combined with the supply pressure of 3.5MPa to 5.5MPa and the impact dynamic pressure at a target distance of 15mm to 25mm, the coking and solidification of the polymer under the heat generated by cutting is synergistically suppressed.

[0012] Preferably, the sampling frequency of the continuously acquired feedback back pressure sequence in step S1 is 18kHz to 21kHz, the sliding time window in step S2 contains 50 continuous back pressure sampling points, and the preset pressure variance threshold in step S3 is 0.1MPa to 0.14MPa; when the frequency-modulated pulse cleaning mode is triggered in step S5, the pulse frequency increases linearly from 90Hz to 120Hz to 2300Hz to 2600Hz, and the pulse rise slope is maintained in the range of 0.8MPa / μs to 1.5MPa / μs.

[0013] Preferably, step S5 further includes the following sub-steps: Step S51, real-time acquisition of the gas Kelvin temperature at the outlet of the airflow nozzle; Step S52, calculation of the deviation between the measured gas Kelvin temperature and the preset reference Kelvin temperature, calculation of the target pulse rising edge slope according to a positive correlation ratio, so that the target pulse rising edge slope increases linearly when the measured gas Kelvin temperature decreases; Step S53, driving the airflow pulse modulation valve to adjust the pulse rising edge slope to the target pulse rising edge slope, thereby enhancing the physical impact kinetic energy by increasing the steepness of the pulse leading edge to offset the attenuation of fluid stripping ability caused by the decrease in gas temperature.

[0014] Preferably, step S5 further includes the following sub-steps: Step S54, while outputting the pulsed airflow in step S5, driving the mechanical displacement mechanism to drive the airflow nozzle to perform axial reciprocating sweeping along the geometric contour of the cutting edge of the oil casing cutting tool, the reciprocating sweeping speed being 5mm / s to 15mm / s; Step S55, controlling the angle between the axis of the airflow nozzle and the normal direction of the topological wall of the oil casing cutting tool to be in the range of 15° to 30°, using the deflection angle spray to generate a lateral shear flow field at the edge of the topological depression, which, together with the shedding vortex, forms a cross-peeling effect.

[0015] Preferably, before step S5, the following sub-steps are included: Step S56, before the pulsed airflow is output in step S5, the gas heating unit is driven to heat the gas output from the high-pressure gas source and maintain the gas temperature in the range of 65°C to 85°C; Step S57, the pressure fluctuation is absorbed by the buffer pressure stabilizing chamber located upstream of the airflow pulse modulation valve, the static pressure fluctuation amplitude at the gas supply pipeline inlet is kept less than 0.05MPa, and the steepness of the pulse leading edge of the airflow pulse modulation valve during the opening and closing switching process conforms to the preset slope range.

[0016] Preferably, in step S5, the rise rate of the driving voltage of the airflow pulse modulation valve is controlled in a stepwise manner: in step S58, when the pressure variance parameter drops from greater than or equal to 0.12MPa to less than 0.12MPa, the driving pulse valve control circuit increases the rise rate of the driving voltage to the preset maximum rise rate within a time interval of 1ms to 2ms, so that the steepness of the leading edge of the pulse airflow jumps to 1.2MPa / μs to 1.5MPa / μs; in step S59, after the large gradient pressure wave excites the shedding vortex, the rise rate of the driving voltage is reduced and maintained at 0.8MPa / μs to 1.1MPa / μs to reduce the mechanical wear of the modulation valve.

[0017] Preferably, step S5 further includes the following sub-steps: step S510, adjusting the high-frequency pulse frequency in the frequency-modulated pulse cleaning mode so that the repetition frequency of the pulse airflow is consistent with the inherent acoustic resonance frequency of the topological recessed cavity of the oil casing cutting tool; step S511, using acoustic resonance to induce local pressure standing waves in the topological recessed cavity, so that the transient pressure peak at the antinode of the standing wave is increased, thereby accelerating the mechanical fatigue fracture of the internal network skeleton of the composite adhesion layer.

[0018] Preferably, after step S5, the following sub-steps are also included: Step S512, in the frequency modulation pulse cleaning mode, the back pressure standard deviation within the sliding time window is continuously calculated; Step S513, when the back pressure standard deviation is continuously maintained in the range of greater than or equal to 0.25MPa and the duration exceeds the preset time threshold, it is determined that the composite adhesion layer on the topological wall of the oil casing cutting tool is completely peeled off and the wall surface returns to the high-frequency turbulent flow field state; Step S514, the airflow pulse modulation valve is driven to stop the high-frequency pulse modulation, and the pulse airflow is switched back to the initial air supply state to complete the online cleaning of the oil casing cutting tool.

[0019] Compared with the prior art, the beneficial effects of the present invention are:

[0020] 1. In the airflow cleaning of oil casing cutting tools, the change in feedback back pressure is used to promptly determine whether the airflow near the topological wall of the oil casing cutting tool is stagnant. This allows the cleaning process to switch cleaning states promptly after the formation of a steady-state aerodynamic boundary layer. The frequency-modulated pulsed airflow can generate strong transient pressure changes and shedding vortices on the tool surface, carrying out the gas trapped in the topological depression area. This weakens the dynamic pressure shielding caused by the steady-state aerodynamic boundary layer, allowing the transient shearing effect generated by the airflow to be effectively transmitted to the composite adhesion layer, thereby improving the peeling ability of high-viscosity polymers and metal debris cross-linked deposits.

[0021] 2. By combining the pressure variance parameter and the skewness parameter of the back pressure sequence, it is possible to further determine whether there is high-pressure gas retention and flow blockage in the tool topology recess area. When this occurs, by shortening the single pressurization time and extending the depressurization time, the high-pressure gas retained in the recess area can be discharged in time, preventing it from blocking the entry of subsequent pulse airflow. This allows the transient impact pressure to act more fully on the deep grooves of the tool, improving the removal effect of composite adhesion layers in complex topology areas and reducing cleaning dead zones and deposit residues.

[0022] 3. By delivering an airflow with an appropriate temperature to the tool surface, the rheological viscosity of the polymer in the composite adhesion layer can be reduced, slowing down its solidification and coking under the action of cutting heat. When the gas temperature decreases or the jet target distance changes during operation, the decrease in the airflow impact capability can be compensated by adjusting the slope of the pulse rising edge, so that the airflow maintains a relatively stable peeling effect on the composite adhesion layer. The viscosity reduction effect of the hot airflow and the transient impact effect of the pulse airflow work together to improve the peeling stability of the composite adhesion layer and reduce coking residue. Attached Figure Description

[0023] Figure 1 This is a flow chart of the frequency-modulated pulse cleaning process with back pressure feedback according to the present invention.

[0024] Figure 2 This is a structural diagram of the frequency modulation pulse airflow cleaning system of the present invention.

[0025] The objectives, features, and advantages of this invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0026] The technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application are within the scope of protection of this application.

[0027] An airflow cleaning process for oil casing cutting tools includes the following steps:

[0028] Step S1: Continuously acquire the feedback back pressure sequence located at the outlet of the airflow nozzle at a preset sampling frequency;

[0029] Step S2: Real-time capture of a preset number of continuous back pressure sampling points to form a sliding time window; calculate the pressure variance parameter of the back pressure sampling points within the sliding time window; use the pressure variance parameter as an objective characterization parameter for determining whether a steady-state aerodynamic boundary layer is formed on the topological wall of the oil casing cutting tool.

[0030] Step S3: Compare the pressure variance parameter with the preset pressure variance threshold.

[0031] Step S4: When the pressure variance parameter is greater than or equal to the preset pressure variance threshold, it is determined that the topological wall of the oil casing cutting tool is in a turbulent stripping state, and the initial air supply parameters are maintained; when the pressure variance parameter is lower than the preset pressure variance threshold, it is determined that the topological wall of the oil casing cutting tool forms a steady-state aerodynamic boundary layer that generates a dynamic pressure shielding effect, and the frequency modulation pulse cleaning mode is triggered.

[0032] Step S5: In the frequency modulation pulse cleaning mode, the airflow pulse modulation valve on the air supply pipeline is driven to adjust the duty cycle and output a pulse airflow with a set air supply pressure, a set gas temperature and a set target distance. The pulse frequency of the pulse airflow is controlled to increase linearly from the initial frequency to a high-frequency pulse, and the pulse rise edge slope of the pulse airflow is kept within the preset slope range. The pulse rise edge slope is used to induce a large gradient pressure wave on the topological wall of the casing cutting tool, which excites the shedding vortex, forcibly entrains and extracts the steady fluid trapped in the topological depression area to break the steady aerodynamic boundary layer, so that the transient shear stress on the wall exceeds the shear yield limit of the composite adhesion layer on the surface of the casing cutting tool, and completes the physical peeling of the composite adhesion layer.

[0033] Preferably, in step S5, the pulsed airflow output by the airflow pulse modulation valve meets the following process conditions: the supply pressure of the pulsed airflow is 3.5MPa to 5.5MPa, the gas temperature is 65°C to 85°C, and the target distance between the airflow nozzle outlet and the surface of the oil casing cutting tool is maintained at 15mm to 25mm. By maintaining the gas temperature of the pulsed airflow in the range of 65°C to 85°C, the rheological viscosity of the polymer in the composite adhesion layer is reduced. Combined with the supply pressure of 3.5MPa to 5.5MPa and the impact dynamic pressure at a target distance of 15mm to 25mm, the coking and solidification of the polymer under the heat generated by cutting is synergistically suppressed.

[0034] Preferably, the sampling frequency of the continuously acquired feedback back pressure sequence in step S1 is 18kHz to 21kHz, the sliding time window in step S2 contains 50 continuous back pressure sampling points, and the preset pressure variance threshold in step S3 is 0.1MPa to 0.14MPa; when the frequency-modulated pulse cleaning mode is triggered in step S5, the pulse frequency increases linearly from 90Hz to 120Hz to 2300Hz to 2600Hz, and the pulse rise slope is maintained in the range of 0.8MPa / μs to 1.5MPa / μs.

[0035] Preferably, step S5 further includes the following sub-steps: Step S51, real-time acquisition of the gas Kelvin temperature at the outlet of the airflow nozzle; Step S52, calculation of the deviation between the measured gas Kelvin temperature and the preset reference Kelvin temperature, calculation of the target pulse rising edge slope according to a positive correlation ratio, so that the target pulse rising edge slope increases linearly when the measured gas Kelvin temperature decreases; Step S53, driving the airflow pulse modulation valve to adjust the pulse rising edge slope to the target pulse rising edge slope, thereby enhancing the physical impact kinetic energy by increasing the steepness of the pulse leading edge to offset the attenuation of fluid stripping ability caused by the decrease in gas temperature.

[0036] Preferably, step S5 further includes the following sub-steps: Step S54, while outputting the pulsed airflow in step S5, driving the mechanical displacement mechanism to drive the airflow nozzle to perform axial reciprocating sweeping along the geometric contour of the cutting edge of the oil casing cutting tool, the reciprocating sweeping speed being 5mm / s to 15mm / s; Step S55, controlling the angle between the axis of the airflow nozzle and the normal direction of the topological wall of the oil casing cutting tool to be in the range of 15° to 30°, using the deflection angle spray to generate a lateral shear flow field at the edge of the topological depression, which, together with the shedding vortex, forms a cross-peeling effect.

[0037] Preferably, before step S5, the following sub-steps are included: Step S56, before the pulsed airflow is output in step S5, the gas heating unit is driven to heat the gas output from the high-pressure gas source and maintain the gas temperature in the range of 65°C to 85°C; Step S57, the pressure fluctuation is absorbed by the buffer pressure stabilizing chamber located upstream of the airflow pulse modulation valve, the static pressure fluctuation amplitude at the gas supply pipeline inlet is kept less than 0.05MPa, and the steepness of the pulse leading edge of the airflow pulse modulation valve during the opening and closing switching process conforms to the preset slope range.

[0038] Preferably, in step S5, the rise rate of the driving voltage of the airflow pulse modulation valve is controlled in a stepwise manner: in step S58, when the pressure variance parameter drops from greater than or equal to 0.12MPa to less than 0.12MPa, the driving pulse valve control circuit increases the rise rate of the driving voltage to the preset maximum rise rate within a time interval of 1ms to 2ms, so that the steepness of the leading edge of the pulse airflow jumps to 1.2MPa / μs to 1.5MPa / μs; in step S59, after the large gradient pressure wave excites the shedding vortex, the rise rate of the driving voltage is reduced and maintained at 0.8MPa / μs to 1.1MPa / μs to reduce the mechanical wear of the modulation valve.

[0039] Preferably, step S5 further includes the following sub-steps: step S510, adjusting the high-frequency pulse frequency in the frequency-modulated pulse cleaning mode so that the repetition frequency of the pulse airflow is consistent with the inherent acoustic resonance frequency of the topological recessed cavity of the oil casing cutting tool; step S511, using acoustic resonance to induce local pressure standing waves in the topological recessed cavity, so that the transient pressure peak at the antinode of the standing wave is increased, thereby accelerating the mechanical fatigue fracture of the internal network skeleton of the composite adhesion layer.

[0040] Preferably, after step S5, the following sub-steps are also included: Step S512, in the frequency modulation pulse cleaning mode, the back pressure standard deviation within the sliding time window is continuously calculated; Step S513, when the back pressure standard deviation is continuously maintained in the range of greater than or equal to 0.25MPa and the duration exceeds the preset time threshold, it is determined that the composite adhesion layer on the topological wall of the oil casing cutting tool is completely peeled off and the wall surface returns to the high-frequency turbulent flow field state; Step S514, the airflow pulse modulation valve is driven to stop the high-frequency pulse modulation, and the pulse airflow is switched back to the initial air supply state to complete the online cleaning of the oil casing cutting tool.

[0041] Example 1: In deep well workover cutting operations, the cutting edge of the tool is subjected to high pressure, strong shearing, and cutting heat. The fine metal debris generated during cutting mixes thermally with the formation polymer and drilling fluid polymer additives, and is deposited on the multi-level topological cutting edge and groove surface of the casing cutting tool, forming a composite adhesion layer with shear yield stress and rheological viscosity. When the tool topological surface is flushed with a continuous steady-state high-pressure airflow, the fluid adheres to the topological wall and accumulates dynamic pressure, forming a steady-state aerodynamic boundary layer with high dynamic pressure characteristics and a dynamic pressure shielding effect. This hinders the subsequent transfer of fluid kinetic energy to the deep topology, preventing the composite adhesion layer in the topological depression from obtaining sufficient peeling energy. Further increasing the gas supply pressure will thicken the wall-attached gas cushion, further aggravating the dynamic pressure shielding in the deep topological depression area and increasing the energy loss of the airflow.

[0042] In this embodiment, the fluid sensing unit is installed at the outlet of the airflow nozzle and continuously acquires the feedback back pressure sequence at the outlet of the airflow nozzle at a sampling frequency of 20kHz. The data processing unit captures 50 consecutive sampling points in real time, forming a sliding time window with a total duration of 2.5ms. The value of each back pressure sampling point within the sliding time window is subtracted from the arithmetic mean of the 50 back pressure sampling points within that window, and the square is calculated. The sum of these 50 squared differences is then divided by 50 to obtain the pressure variance parameter within the sliding time window. The data processing unit directly sets the preset pressure variance threshold to a range of 0.0100MPa² to 0.0196 square MPa, corresponding to the pressure deviation threshold of 0.10MPa to 0.14MPa. In this embodiment, it is specifically set to 0.0144MPa². When the calculated pressure variance parameter... When the value is 0.00000383MPa², it is lower than the variance domain comparison threshold. Based on this, the control unit determines that the three-dimensional physical wall, including the main cutting edge rake face, chip removal groove surface, and clearance groove of the oil casing cutting tool, forms a steady-state aerodynamic boundary layer that generates a dynamic pressure shielding effect, and triggers the frequency modulation pulse cleaning mode.

[0043] In frequency-modulated pulse cleaning mode, the gas supply unit maintains the gas supply pressure at 4.5 MPa and the gas temperature at 75°C. The target distance between the airflow nozzle outlet and the surface of the oil casing cutting tool is maintained at 20 mm. The control unit drives the airflow pulse modulation valve installed on the air supply pipeline to increase the pulse output frequency from an initial 100 Hz to 2500 Hz within 2 ms in a continuous step-by-step manner, increasing the pulse frequency by 100 Hz every discrete step period of 0.083 ms. This is done along a linear step-by-step path with a constant slope of 1200 Hz per millisecond. Simultaneously, the valve drive circuit adjusts the pulse rise edge slope of the pulse airflow to 1.15 MPa / μs. The pulse rise edge slope within the range of 0.8 to 1.5 MPa / μs is consistent with the linear step-by-step increase from 100 Hz. The high-frequency pulses, surging to 2500Hz, work together with the 1.15MPa / μs pulse leading edge steepness and the 2500Hz high-frequency airflow displacement effect on the tool topology wall to directly entrain and blow away the 150μm thick low-speed stagnant air layer inside the chip removal groove. This allows the dynamic pressure of the pulsed airflow to be transmitted to the tool surface without attenuation, generating a wall shear stress of 1.38kPa, which directly exceeds the shear yield limit of the composite adhesion layer of 0.85kPa, completing the physical peeling of the composite adhesion layer. At the same time, the hot airflow with a temperature range of 65℃ to 85℃ continuously replenishes heat to the tool surface, reducing the rheological viscosity of the polymer in the composite adhesion layer. The impact dynamic pressure generated by the pulse rising edge slope, combined with the thermal viscosity reduction effect, suppresses the thickening of the wall-attached air cushion caused by the increase in air supply pressure.

[0044] Under the action of transient shedding vortex and impact dynamic pressure, the thickness of the aerodynamic boundary layer on the tool surface is reduced from 180μm during steady-state flushing to 40μm, with the boundary layer thickness reduction gradient increasing by 350%. The transient wall shear stress generated in the peeling area reaches 1.38kPa, exceeding the shear yield limit of 0.85kPa and the critical threshold of 1.2kPa of the composite adhesion layer, breaking the solid-liquid physical cross-linking structure between the long polyacrylamide polymer chain and the cutting metal micro-chips with a particle size of 1μm to 50μm. This allows the composite adhesion layer on the cutting edge to be peeled off within 1.2s without any residual polymer coking. The total air consumption is reduced by 42% compared to steady-state flushing. This process identifies the formation of the steady-state aerodynamic boundary layer by the pressure variance parameter of the feedback back pressure sequence and uses frequency-modulated pulse airflow to remove the aerodynamic shielding, replacing the cleaning method of simply increasing the steady-state fluid kinetic energy, so that the system maintains the composite adhesion layer peeling and low air consumption operation.

[0045] Example 2: This example demonstrates the peeling process of the airflow cleaning process on the topological surface of a casing cutting tool. An airflow cleaning test platform was constructed. The output pressure of the gas supply unit was adjustable within the range of 3.5 to 5.5 MPa, and the temperature control accuracy was ±0.5℃. A piezoelectric fluid sensing unit with a range of 0 to 10 MPa and a sampling frequency of 20 kHz was installed at the outlet of the airflow nozzle. A miniature pressure sensor array was arranged on the tool wall, and a laser Doppler velocimeter was used to measure the steady-state aerodynamic boundary layer thickness and the transient shear stress on the wall. The signal-to-noise ratio superimposed in the acquired signals was 20 dB. Gaussian white noise and 50Hz power frequency interference harmonics were used to simulate strong downhole vibration and electromagnetic interference. The cutoff frequency of the feedback back pressure high-frequency pulse waveform was around 8kHz, and the sampling frequency was set to 20kHz with a bandwidth of more than 2.5 times. The sliding time window contained 50 continuous sampling points, corresponding to a data window length of 2.5ms. The basic working conditions were 4.5MPa air supply pressure, 75℃ air supply temperature, and 20mm target distance. A 180μm thick polymer and metal chip composite adhesion layer was deposited on the surface of the cutting tool, with a shear yield limit of 0.85kPa.

[0046] The test subjects were set up according to five independent sample groups, including the sample group of the present invention using dynamic sensing and frequency-modulated pulse cleaning mode, control group 1 using continuous steady-state airflow injection, control group 2 using a fixed frequency of 1000Hz without feedback back pressure adjustment, control group 3 using a low pulse rise edge slope, and control group 4 using an ultra-high pulse rise edge slope. A sample group with missing skewness adjustment was also set up. The sample groups of the present invention were tested under standard operating conditions, low temperature boundary operating conditions, and high temperature upper limit operating conditions.

[0047] After each sample group is started, the fluid sensing unit continuously collects the feedback back pressure sequence at the outlet of the airflow nozzle. The data processing unit averages the squared deviations of 50 consecutive sampling points relative to their arithmetic mean to obtain the pressure variance parameter. The nominal value of the preset pressure variance threshold is 0.12 MPa. Its corresponding threshold in the variance calculation domain is determined according to the calibration results of the sensor measurement channel. When the pressure judgment value used for threshold comparison drops from 0.15 MPa in the initial high-frequency turbulent state to below 0.12 MPa, the corresponding pressure variance parameter is 0.00000383 MPa². The control unit determines that a steady-state aerodynamic boundary layer has been formed and steps the pulse frequency from 100 Hz to 2500 Hz within 2 ms.

[0048] The data processing unit continues to calculate the skewness parameter of the feedback backpressure sequence using the following formula. When the pressure judgment value is lower than the preset pressure variance threshold, and When the value is -0.68 and below -0.5, the control unit determines that there is a local high-pressure air cushion and fluid blockage deep in the topology, and the airflow pulse modulation valve reduces the switching duty cycle from the initial 50% to 35%.

[0049] Under low-temperature boundary conditions, the supply gas pressure is 3.5 MPa, the gas temperature is 338.15 K (65°C), and the pulse frequency is 2500 Hz. The data processing unit calculates the target pulse rise edge slope using the following formula. : ,in, The reference rising edge slope is set to 1.15 MPa / μs. The preset reference Kelvin temperature is set to 348.15K, corresponding to 75℃. To measure the Kelvin temperature of the gas, The temperature compensation coefficient is set to 0.45, and the calculation yields... The pressure is 1.165 MPa / μs. The airflow pulse modulation valve adjusts the pulse rise slope accordingly. Under this condition, the pressure variance parameter is 0.00000210 MPa², the skewness parameter is -0.72, the steady-state aerodynamic boundary layer thickness is 43 μm, the wall transient shear stress is 1.22 kPa, the peeling time of the composite adhesion layer is 1.8 s, and the air consumption change is -38%. The wall transient shear stress is still higher than the critical threshold of 1.2 kPa.

[0050] Under standard operating conditions, the pulse frequency reaches 2500Hz, the pulse rise slope is 1.15MPa / μs, the steady-state aerodynamic boundary layer thickness is reduced to 40μm, the transient shear stress on the wall reaches 1.38kPa, the composite adhesion layer is peeled off within 1.2s, and the gas consumption changes by -42%. Compared with continuous steady-state airflow injection, the gradient of the reduction in steady-state aerodynamic boundary layer thickness is increased by 350%.

[0051] Under the high-temperature upper limit operating conditions, the gas supply pressure is 5.5 MPa, the gas temperature is 85℃, the pulse frequency is 2500 Hz, the pulse rise slope is 1.15 MPa / μs, the pressure variance parameter is 0.00000412 MPa², the skewness parameter is -0.55, the steady-state aerodynamic boundary layer thickness is 38 μm, the transient shear stress on the wall is 1.45 kPa, the peeling time is 1.0 s, and the gas consumption change is -45%.

[0052] All control groups and missing skewness adjustment groups used a gas supply pressure of 4.5 MPa and a gas temperature of 75 °C. Control group 1 used continuous steady-state gas injection with a pulse frequency of 0 Hz and a pulse rise slope of 0.00 MPa / μs. The pressure variance parameter was 0.00000150 MPa², the skewness parameter was -0.12, the steady-state aerodynamic boundary layer thickness was maintained at 180 μm, the transient shear stress on the wall was 0.35 kPa, the composite adhesion layer was not peeled off, the gas consumption change was 0%, the transient shear stress on the wall was lower than the shear yield limit of the composite adhesion layer, and the cross-linked network formed by the polymer and metal debris was not broken.

[0053] Control group 2 used a fixed 1000Hz pulse, with a recorded pulse rise slope of 0.50MPa / μs, a pressure variance parameter of 0.00001200MPa², a skewness parameter of -0.25, a steady-state aerodynamic boundary layer thickness of 115μm, a wall transient shear stress of 0.72kPa, a peeling time of 4.8s, and a gas consumption change of -15%. Under the conditions of fixed frequency and no feedback back pressure adjustment, the wall transient shear stress still did not reach the shear yield limit of the composite adhesion layer.

[0054] Both control groups 3 and 4 had a pulse frequency of 2500 Hz. Control group 3 had a pulse rise slope of 0.50 MPa / μs, resulting in a pressure variance of 0.00000390 MPa², a skewness parameter of -0.65, a steady-state aerodynamic boundary layer thickness of 92 μm, a wall transient shear stress of 0.78 kPa, a peeling time of 3.9 s, and a gas consumption change of -22%. Control group 4 had a pulse rise slope of 1.80 MPa / μs, resulting in a pressure variance of... The differential parameter is 0.00000375 MPa², the skewness parameter is -0.70, the steady-state aerodynamic boundary layer thickness is 41 μm, the transient shear stress on the wall is 1.40 kPa, the peeling time is 1.3 s, and the gas consumption change is -28%. As the pulse rising edge slope continues to increase, the increase in transient shear stress on the wall decreases, the power consumption of the modulated valve drive circuit increases, and the mechanical jitter increases by 240%. Based on this, 0.8 to 1.5 MPa / μs is taken as the working range of pulse rising edge slope.

[0055] The sample group lacking skewness adjustment used a pulse frequency of 2500Hz and a pulse rise slope of 1.15MPa / μs, with a pressure variance parameter of 0.00000380MPa² and a skewness parameter of -0.68. Under this skewness condition, a 50% duty cycle was maintained, the steady-state aerodynamic boundary layer thickness was 75μm, the transient shear stress on the wall was 0.95kPa, the peeling time was 2.6s, and the gas consumption change was -30%. Compared with the standard operating condition with skewness adjustment, without reducing the duty cycle, the pressure relief window was not extended, the high-pressure gas trapped deep in the topology was not fully released, and the transient shear stress on the wall decreased accordingly.

[0056] In the above data, the pressure variance parameter is used to identify the formation of the steady-state aerodynamic boundary layer, and the skewness parameter is used to identify the fluid blockage state in the deep topology. After triggering the frequency-modulated pulse cleaning mode, the pulse frequency step, the pulse rise slope within the specified range, the switch duty cycle adjustment, and the gas temperature compensation together change the pulse airflow at the outlet of the airflow nozzle, so that the transient shear stress on the wall exceeds the shear yield limit of the composite adhesion layer, and reduces the consumption of high-pressure gas and polymer coking residue.

[0057] Example 3: During the operation of the airflow cleaning system, the airflow pulse modulation valve in the air supply pipeline is electrically connected to the valve drive circuit. The valve drive circuit includes a high-voltage pulse drive module with an adjustable drive voltage rise rate. The piezoelectric fluid sensing unit at the airflow nozzle outlet acquires the feedback back pressure sequence at a sampling frequency of 20kHz. The data processing unit stores 50 consecutive sampling points into a circular buffer and continuously calculates the pressure variance parameter using a sliding time window of 2.5ms. .

[0058] When the pressure judgment value used for threshold comparison decreases from the turbulent state to below 0.12 MPa, and the pressure variance parameter... When the data enters below the corresponding variance domain comparison threshold, the data processing unit outputs a high-level trigger signal to the control unit. The control unit starts the frequency modulation pulse cleaning mode and sends a frequency control command and a drive voltage rise rate adjustment command to the valve drive circuit, so that the pulse frequency increases from 100Hz to 2500Hz within 2ms. The high-voltage pulse drive module first adjusts the drive voltage rise rate output to the airflow pulse modulation valve coil to 48V / μs, drives the valve core to open within 0.1μs, so that the pulse rise edge slope at the airflow nozzle outlet reaches 1.15MPa / μs, and generates a large gradient pressure wave on the topological wall of the oil casing cutting tool.

[0059] In pressure variance parameter During the process of decreasing from above the threshold to below the threshold, the valve drive circuit increases the rate of rise of the drive voltage stepwise from the current value to the preset maximum rate of rise within 1 to 2 ms, so that the slope of the pulse rising edge jumps to 1.2 to 1.5 MPa / μs to excite the shedding vortex and break the steady-state aerodynamic boundary layer. After the shedding vortex is formed, the valve drive circuit reduces the rate of rise of the drive voltage and maintains the slope of the pulse rising edge at 0.8 to 1.1 MPa / μs, thereby reducing the mechanical wear of the airflow pulse modulation valve during continuous opening and closing.

[0060] During operation in frequency-modulated pulse cleaning mode, the data processing unit completes the pressure variance parameter within a 2.5ms sliding time window. The operation involves calling the higher-order moment calculation module to calculate the skewness parameter based on 50 consecutive feedback backpressure sampling points within the window and their arithmetic mean. When the pressure judgment value is below 0.12 MPa, and the skewness parameter When the value is below -0.5, it indicates that the feedback back pressure sequence is negatively skewed, and there is a high-pressure gas cushion trapped deep in the topological depression of the oil casing cutting tool. Based on this, the data processing unit switches the state value of the duty cycle control register from the initial 50% to 35%. The control unit modifies the PWM comparator setting of the valve drive circuit according to the register state, shortening the single pulse pressurization time from 0.2ms to 0.14ms, while extending the depressurization time to 0.26ms. This accelerates the release of the trapped high-pressure gas in the deep topological depression and keeps the transient shear stress on the wall above the shear yield limit of the composite adhesion layer of 0.85kPa.

[0061] The temperature sensing unit collects the Kelvin temperature of the gas at the outlet of the airflow nozzle in real time. When the average temperature over 10 consecutive sampling periods deviates from the preset reference Kelvin temperature And the gas Kelvin temperature When the voltage drops from 348.15K to 338.15K, the data processing unit adjusts the voltage based on the rise slope of the reference voltage. 1.15 MPa / μs, temperature compensation coefficient Given a relationship of 0.45, the slope of the rising edge of the target pulse is calculated. The target value is 1.165 MPa / μs. The data processing unit converts this target value into a drive voltage rise rate correction, which causes the high-voltage pulse drive module to increase the drive voltage rise rate from 48 V / μs to 48.6 V / μs to offset the decrease in fluid stripping ability caused by the drop in gas temperature. Under this temperature compensation state, the transient wall shear stress acting on the surface of the oil casing cutting tool is maintained at 1.22 kPa, and the composite adhesion layer in the topological recess area of ​​the cutting edge is continuously subjected to shearing action higher than its shear yield limit.

[0062] Example 4: This example combines Figures 1 to 2 This paper describes an airflow cleaning process for an oil casing cutting tool, such as... Figure 1As shown, the first node at the top, step S1, records the continuous acquisition of the feedback back pressure sequence at the outlet of the airflow nozzle at a preset sampling frequency. The node of step S1 points downwards to the node of step S2, and this node records the interception of continuous back pressure sampling points to form a sliding time window, calculating the pressure variance parameter, which is used as an objective characteristic parameter to determine whether a steady-state aerodynamic boundary layer has formed on the tool topology wall. The node of step S2 points downwards to the node of step S3, and this node records the comparison of the pressure variance parameter with a preset pressure variance threshold. The node of step S3 points downwards to the node of step S3... When the node in step S4 has a variance parameter greater than or equal to the threshold, the initial air supply is maintained; when it is lower than the threshold, it is determined that a steady-state aerodynamic boundary layer with a dynamic pressure shielding effect is formed, and the frequency modulation pulse cleaning mode is triggered. The node in step S4 points down to the node in step S5, and the node has a drive airflow pulse modulation valve outputting a set pulse airflow. The pulse frequency is controlled to increase linearly from the initial frequency to a high-frequency pulse while keeping the rising slope within a preset range, inducing a large gradient pressure wave and exciting a shedding vortex, breaking the steady-state aerodynamic boundary layer, and completing the physical peeling of the composite adhesion layer.

[0063] like Figure 2 As shown, the data processing unit provides an output path to the control unit, the control unit provides a transmission path to the valve drive circuit and a drive path to the mechanical displacement mechanism, the fluid sensing unit performs acquisition interaction with the airflow nozzle and provides an interception path to the data processing unit, the temperature sensing unit performs acquisition interaction with the airflow nozzle and provides an interception path to the data processing unit, the internal dashed box of the valve drive circuit contains the high-pressure pulse drive module and forms an electrical connection between the valve drive circuit and the airflow pulse modulation valve, the mechanical displacement mechanism forms a driving connection to the airflow nozzle, the high-pressure gas source provides an output path to the gas heating unit, the gas heating unit provides a ventilation path to the buffer pressure stabilizing chamber, the buffer pressure stabilizing chamber provides a ventilation path to the airflow pulse modulation valve, the airflow pulse modulation valve provides pulsed airflow to the airflow nozzle, the airflow nozzle outputs impact dynamic pressure to the oil casing cutting tool, and the internal dashed box of the oil casing cutting tool contains a composite adhesion layer.

[0064] Example 5: In the preparatory stage of cleaning the oil casing cutting tool, the airflow nozzle is in an unloaded pipeline ventilation state, and the fluid sensing unit acquires the static feedback back pressure sequence at a sampling frequency of 20kHz. The data processing unit extracts 200 consecutive back pressure sampling points, calculates the static zero-point offset, and stores it in the calibration register as the reference deduction for subsequent feedback back pressure measurements.

[0065] After completing the static zero-point calibration, the gas supply pressure was adjusted to 4.5 MPa, and an open flow field without tool obstruction was maintained in front of the gas nozzle. The data processing unit extracted 50 consecutive back pressure sampling points to form a sliding time window and calculated the background noise variance parameter. ,when When the pressure remains stable within a range of less than 0.000001 MPa², it is determined that there are no abnormal pressure fluctuations in the sensor measurement channel and the air supply pipeline; after calibration of the measurement channel, it is confirmed that the variance judgment limit corresponding to the preset pressure variance threshold with a nominal pressure value of 0.12 MPa is higher than the set value. This completes the measurement baseline calibration before cleaning status identification.

[0066] Before driving the airflow pulse modulation valve, the control unit applies a test step signal to the high-voltage pulse drive module in the valve drive circuit. The fluid sensing unit acquires the pressure response at the airflow nozzle outlet and measures the opening response delay of the airflow pulse modulation valve. When the opening response delay is within the range of 0.05 to 0.1 μs, the high-voltage pulse drive module sets the initial drive voltage rise rate to 48V / μs, making the measured pulse rise slope at the airflow nozzle outlet... Slope of the rising edge of the reference line Aligned to 1.15 MPa / μs, where, This represents the measured pulse rise slope.

[0067] The temperature sensing unit synchronously collects the Kelvin temperature of the gas at the outlet of the airflow nozzle. The gas heating unit preheats the gas to a Kelvin temperature. With preset reference Kelvin temperature The deviation between them does not exceed 0.5K, where The temperature is 348.15K; under this condition, the temperature compensation coefficient is... Keep it at 0.45 to complete the in-situ parameter alignment before starting the frequency modulation pulse cleaning mode.

[0068] Example 6: When the pulsed airflow is injected in the frequency-modulated pulse cleaning mode, the control unit synchronously drives the mechanical displacement mechanism to drive the airflow nozzle to perform axial reciprocating sweeping along the geometric contour of the cutting edge of the oil casing cutting tool. The reciprocating sweeping speed is maintained at 10 mm / s. At the same time, the angle between the axis of the airflow nozzle and the normal direction of the topological wall of the oil casing cutting tool is maintained at 22°, so that the angled jet airflow forms a lateral shear flow field at the edge of the topological depression. This lateral shear flow field and the transient shedding vortex excited by the large gradient pressure wave act together on the topological depression area of ​​the cutting edge, forming cross-peeling of the cross-linked network skeleton of the composite adhesion layer.

[0069] In the frequency-modulated pulse cleaning mode, the control unit drives the airflow pulse modulation valve. Based on the acoustic reciprocating reflection period of 0.4ms corresponding to the chip removal groove depth of 12mm to 15mm, the pulse repetition frequency of the airflow pulse modulation valve is set to 2300Hz to 2600Hz, specifically adjusted to 2500Hz. This causes the pulse airflow at the bottom of the chip removal groove to superimpose and form a transient impact pressure with a peak value of 5.2MPa. This causes the alternating stress amplitude acting on the bonding interface of the composite adhesion layer to reach 1.45MPa, driving the composite adhesion layer to peel and break at the interface with the tool substrate, completing the online cleaning of the oil casing cutting tool, and then adaptively exiting the frequency-modulated pulse cleaning mode.

[0070] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention.

[0071] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. An airflow cleaning process for oil casing cutting tools, characterized in that, Includes the following steps: Step S1: Continuously acquire the feedback back pressure sequence located at the outlet of the airflow nozzle at a preset sampling frequency; Step S2: Real-time capture of a preset number of continuous back pressure sampling points to form a sliding time window; calculate the pressure variance parameter of the back pressure sampling points within the sliding time window; use the pressure variance parameter as an objective characterization parameter for determining whether a steady-state aerodynamic boundary layer is formed on the topological wall of the oil casing cutting tool. Step S3: Compare the pressure variance parameter with the preset pressure variance threshold. Step S4: When the pressure variance parameter is greater than or equal to the preset pressure variance threshold, it is determined that the topological wall of the oil casing cutting tool is in a turbulent stripping state, and the initial air supply parameters are maintained; when the pressure variance parameter is lower than the preset pressure variance threshold, it is determined that the topological wall of the oil casing cutting tool forms a steady-state aerodynamic boundary layer that generates a dynamic pressure shielding effect, and the frequency modulation pulse cleaning mode is triggered. Step S5: In the frequency modulation pulse cleaning mode, the airflow pulse modulation valve on the air supply pipeline is driven to adjust the duty cycle and output a pulse airflow with a set air supply pressure, a set gas temperature and a set target distance. The pulse frequency of the pulse airflow is controlled to increase linearly from the initial frequency to a high-frequency pulse, and the pulse rise edge slope of the pulse airflow is kept within the preset slope range. The pulse rise edge slope is used to induce a large gradient pressure wave on the topological wall of the casing cutting tool, which excites the shedding vortex, forcibly entrains and extracts the steady fluid trapped in the topological depression area to break the steady aerodynamic boundary layer, so that the transient shear stress on the wall exceeds the shear yield limit of the composite adhesion layer on the surface of the casing cutting tool, and completes the physical peeling of the composite adhesion layer.

2. The airflow cleaning process for oil casing cutting tools according to claim 1, characterized in that, In step S5, the pulsed airflow output by the pulsed airflow modulation valve meets the following process conditions: the supply pressure of the pulsed airflow is 3.5MPa to 5.5MPa, the gas temperature is 65℃ to 85℃, and the target distance between the airflow nozzle outlet and the surface of the oil casing cutting tool is maintained at 15mm to 25mm. By maintaining the gas temperature of the pulsed airflow in the range of 65℃ to 85℃, the rheological viscosity of the polymer in the composite adhesion layer is reduced. Combined with the supply pressure of 3.5MPa to 5.5MPa and the impact dynamic pressure at a target distance of 15mm to 25mm, the coking and solidification of the polymer under the heat generated by cutting is synergistically suppressed.

3. The airflow cleaning process for oil casing cutting tools according to claim 1, characterized in that, In step S1, the sampling frequency of the continuously acquired feedback back pressure sequence is 18kHz to 21kHz. In step S2, the sliding time window contains 50 continuous back pressure sampling points. In step S3, the preset pressure variance threshold is 0.1MPa to 0.14MPa. When the frequency-modulated pulse cleaning mode is triggered in step S5, the pulse frequency increases linearly from 90Hz to 120Hz to 2300Hz to 2600Hz, and the pulse rise slope is maintained in the range of 0.8MPa / μs to 1.5MPa / μs.

4. The airflow cleaning process for oil casing cutting tools according to claim 3, characterized in that, Step S5 further includes the following sub-steps: Step S51, real-time acquisition of the gas Kelvin temperature at the outlet of the airflow nozzle; Step S52, calculation of the deviation between the measured gas Kelvin temperature and the preset reference Kelvin temperature, calculation of the target pulse rising edge slope according to a positive correlation ratio, so that the target pulse rising edge slope increases linearly when the measured gas Kelvin temperature decreases; Step S53, driving the airflow pulse modulation valve to adjust the pulse rising edge slope to the target pulse rising edge slope, thereby enhancing the physical impact kinetic energy by increasing the steepness of the pulse leading edge to offset the attenuation of fluid stripping ability caused by the decrease in gas temperature.

5. The airflow cleaning process for oil casing cutting tools according to claim 1, characterized in that, Step S5 also includes the following sub-steps: Step S54, while outputting the pulsed airflow in step S5, the mechanical displacement mechanism is driven to drive the airflow nozzle to perform axial reciprocating sweeping along the geometric contour of the cutting edge of the oil casing cutting tool, and the reciprocating sweeping speed is 5mm / s to 15mm / s; Step S55, the angle between the axis of the airflow nozzle and the normal direction of the topological wall of the oil casing cutting tool is controlled to be in the range of 15° to 30°, and the lateral shear flow field is generated at the edge of the topological depression by the deflection spray, which, together with the shedding vortex, forms a cross-peeling effect.

6. The airflow cleaning process for oil casing cutting tools according to claim 2, characterized in that, Before step S5, the following sub-steps are also included: Step S56, before the pulsed airflow is output in step S5, the gas heating unit is driven to heat the gas output from the high-pressure gas source and maintain the gas temperature in the range of 65°C to 85°C; Step S57, the pressure fluctuation is absorbed by the buffer pressure stabilizing chamber located upstream of the airflow pulse modulation valve, the static pressure fluctuation amplitude at the gas supply pipeline inlet is kept less than 0.05MPa, and the steepness of the pulse leading edge of the airflow pulse modulation valve during the opening and closing switching process is kept in accordance with the preset slope range.

7. The airflow cleaning process for oil casing cutting tools according to claim 3, characterized in that, In step S5, the rise rate of the driving voltage of the airflow pulse modulation valve is controlled in a stepwise manner: In step S58, when the pressure variance parameter drops from greater than or equal to 0.12MPa to less than 0.12MPa, the driving pulse valve control circuit increases the rise rate of the driving voltage to the preset maximum rise rate within a time interval of 1ms to 2ms, so that the steepness of the leading edge of the pulse airflow jumps to 1.2MPa / μs to 1.5MPa / μs; In step S59, after the large gradient pressure wave excites the shedding vortex, the rise rate of the driving voltage is reduced and maintained at 0.8MPa / μs to 1.1MPa / μs to reduce the mechanical wear of the modulation valve.

8. The airflow cleaning process for oil casing cutting tools according to claim 1, characterized in that, Step S5 further includes the following sub-steps: Step S510, adjusting the high-frequency pulse frequency in the frequency-modulated pulse cleaning mode so that the repetition frequency of the pulse airflow is consistent with the inherent acoustic resonance frequency of the topological recessed cavity of the oil casing cutting tool; Step S511, using acoustic resonance to induce local pressure standing waves in the topological recessed cavity, so that the transient pressure peak at the antinode of the standing wave is increased, accelerating the mechanical fatigue fracture of the internal network skeleton of the composite adhesion layer.

9. The airflow cleaning process for oil casing cutting tools according to claim 1, characterized in that, After step S5, the following sub-steps are also included: Step S512, in the frequency modulation pulse cleaning mode, the back pressure standard deviation within the sliding time window is continuously calculated; Step S513, when the back pressure standard deviation is continuously maintained in the range of greater than or equal to 0.25MPa and the duration exceeds the preset time threshold, it is determined that the composite adhesion layer on the topological wall of the oil casing cutting tool is completely peeled off and the wall surface returns to the high-frequency turbulent flow field state; Step S514, the drive airflow pulse modulation valve stops the high-frequency pulse modulation, switches the pulse airflow back to the initial air supply state, and completes the online cleaning of the oil casing cutting tool.

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