A well repair liquid level monitoring and intelligent control method

Abstract

The application discloses a kind of well repair fluid level monitoring and intelligent control method of liquid injection, comprising the following steps: one, the well repair fluid level monitoring and intelligent control system is established;Two, set formation pressure window interval;Three, divide formation pressure in window interval within the dynamic fluid level uphole velocity grade;Four, collect the dynamic fluid level height and wellbore pressure in oil well wellbore;Five, judge whether dynamic fluid level height is at wellhead;Six, well repair oil pipe and liquid injection;Seven, calculate the dynamic fluid level change height in oil well wellbore;Eight, judge whether the dynamic fluid level change height in oil well wellbore is negative;Nine, judge whether dynamic fluid level uphole velocity belongs to two dynamic fluid level uphole velocities;Ten, well repair fluid level monitoring and rapid liquid injection;Eleven, well repair fluid level monitoring and self-adapting liquid injection.The application adjusts liquid injection amount in time according to fluid level change, carries out accurate liquid injection, ensures that wellbore liquid column height is stable, guarantees that wellbore liquid column pressure and formation pressure are balanced, controls leakage and prevents blowout in time, realizes one well one control.

Description

Technical Field

[0001] This invention belongs to the field of well control safety and well workover fluid injection technology in oilfield well workover operations, specifically involving a method for monitoring well workover fluid level and intelligent control of fluid injection. Background Technology

[0002] Well control safety is the top priority in oil and gas well exploration and development, especially in the context of intelligent well workover operations. During workover, pressure-sensitive formations are prone to active oil and gas, making them susceptible to both leakage and overflow. There is a safety window for hydraulic pressure; when the hydraulic pressure exceeds the formation pressure, well leakage may occur, potentially leading to significant losses. When the hydraulic pressure is lower than the bottom hole circulation pressure, well kick or even blowout may occur, resulting in a major safety accident. Current workover fluid level monitoring and injection methods often use fixed-mount wellbore fluid level monitoring devices at the wellhead. When an abnormality is detected, fluid is injected in a timed or quantitative manner. However, this often results in well leakage accidents when the wellbore pressure is at the critical formation pressure value due to continuous injection. Furthermore, it sometimes overlooks situations where the fluid rises too rapidly within the formation pressure window, leading to missed critical injection times and subsequent well kicks or blowouts. Summary of the Invention

[0003] The technical problem to be solved by this invention is to address the shortcomings of the prior art by providing a method for monitoring well workover fluid level and intelligent control of injection. This method monitors the dynamic fluid level changes within a window range of formation pressure in real time, enabling timely adaptive grouting. Simultaneously, it controls the fluid rise rate, strictly implements high-density injection, and adjusts the injection regime according to fluid level changes for precise injection. This achieves intelligent injection control, ensuring stable fluid column height within the wellbore, maintaining a balance between fluid column pressure and formation pressure, timely controlling leakage and preventing blowouts. Real-time, continuous, and accurate monitoring of wellbore fluid level changes enables one-well-one-control, providing effective technical support for effective plugging and well control safety, and facilitating widespread application.

[0004] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a method for monitoring well workover fluid level and intelligent control of injection, characterized in that the method includes the following steps:

[0005] Step 1: Establish a well workover fluid level monitoring and injection intelligent control system. The well workover fluid level monitoring and injection intelligent control system includes a wellhead fluid level measuring instrument installed on the wellbore branch pipe of the oil well and used to detect the dynamic fluid level height and wellbore pressure in the oil wellbore, and an injection pool for injecting workover fluid into the oil wellbore. A blowout preventer, an overflow preventer and a well sealer are installed in sequence on the top of the oil wellbore. One end of the injection pipe is connected to the injection pool, and the other end of the injection pipe passes through the well sealer, the overflow preventer and the blowout preventer in sequence and extends into the oil wellbore. The wellhead fluid level measuring instrument is installed on the wellbore branch pipe through an installation valve. An injection pump is installed on the section of the injection pipe located on the ground. Both the installation valve and the injection pump are controlled by a control box on the ground. The signal output terminal of the wellhead fluid level measuring instrument is connected to the input terminal of the control box.

[0006] Step 2: Set the formation pressure window range;

[0007] Step 3: Classify the velocity levels of formation pressure on the fluid surface within the window range: Classify the velocity levels of formation pressure on the fluid surface within the window range according to the velocity of formation pressure on the fluid surface. The velocity levels of formation pressure on the fluid surface within the window range include primary velocity and secondary velocity, and the primary velocity is less than the secondary velocity.

[0008] When the velocity v0 of the formation pressure on the surface of the dynamic fluid within the window is less than the threshold velocity of the dynamic fluid, the velocity v0 of the formation pressure on the surface of the dynamic fluid within the window is considered to be a first-order dynamic fluid surface velocity.

[0009] When the velocity v0 of the formation pressure on the surface of the dynamic fluid within the window is not less than the threshold velocity of the dynamic fluid surface, the velocity v0 of the formation pressure on the surface of the dynamic fluid within the window is a secondary velocity of the dynamic fluid surface.

[0010] Step 4: Use a wellhead fluid level measuring instrument to collect the dynamic fluid level height and wellbore pressure inside the oil well;

[0011] Step 5: Determine if the dynamic fluid level is at the wellhead. If the wellhead fluid level measuring instrument detects that the dynamic fluid level inside the wellbore is at the wellhead, proceed to Step 6; if the wellhead fluid level measuring instrument detects that the dynamic fluid level inside the wellbore is inside the well, proceed to Step 7.

[0012] Step Six: Well workover, tubing removal, and fluid injection, the process is as follows:

[0013] Step 601: Set the dynamic liquid level height range;

[0014] Step 602: Pull out the tubing multiple times at fixed time intervals. The number of tubing sections pulled out each time is fixed. Each time the tubing is pulled out, use a wellhead fluid level measuring instrument to detect the dynamic fluid level height inside the wellbore once, until the current dynamic fluid level height is within the dynamic fluid level height range.

[0015] Step 603: Continue pulling in the tubing and use the wellhead fluid level gauge to detect the dynamic fluid level in the wellbore. If the current dynamic fluid level remains within the dynamic fluid level range, the injection pump will not work, and there is no need to add workover fluid to the wellbore. If the current dynamic fluid level is below the dynamic fluid level range, add workover fluid to the wellbore to keep the current dynamic fluid level within the dynamic fluid level range.

[0016] Step 604: Repeat step 603 multiple times until the oil pipe is lifted M times in a row and the dynamic fluid level shows an upward trend, then end the oil pipe lifting process.

[0017] Step 7: Calculate the dynamic fluid level change height inside the oil wellbore: Use a wellhead fluid level measuring instrument to detect the dynamic fluid level height inside the oil wellbore N times at fixed time intervals, and calculate the change height according to the formula. Calculate the height h of the dynamic fluid level inside the wellbore during this exploration process. 1 Where n is the number of times the dynamic fluid level height inside the oil wellbore was detected during this exploration, N is the total number of times the dynamic fluid level height inside the oil wellbore was detected during this exploration, and h n This refers to the height of the dynamic fluid level inside the wellbore during the nth detection in this exploration process.

[0018] According to the formula Δh=h 1 -h 0 Calculate the height Δh of the dynamic fluid level change within the oil wellbore, where h 0 The height of the dynamic fluid level inside the wellbore obtained during the previous exploration process;

[0019] Step 8: Determine if the change in dynamic fluid level Δh in the wellbore is negative: When the change in dynamic fluid level Δh in the wellbore is non-negative, the injection pump will not work, and there is no need to add workover fluid to the wellbore; when the change in dynamic fluid level Δh in the wellbore is negative, proceed to step 9.

[0020] Step 9: Determine whether the formation pressure velocity v0 on the hydrodynamic surface within the window range belongs to the second-order hydrodynamic surface velocity: According to the formula... Calculate the formation pressure surface velocity v0 within the window interval, where T is the total time of this detection process. When the formation pressure surface velocity v0 within the window interval is not less than the surface velocity threshold, the formation pressure surface velocity v0 within the window interval belongs to the second-level surface velocity, and proceed to step ten; otherwise, proceed to step eleven.

[0021] Step 10, Well Workover Fluid Level Monitoring and Rapid Fluid Injection: The control box controls the injection pump to fully open and inject workover fluid into the wellbore. At the same time, the wellhead fluid level measuring instrument is used to collect the dynamic fluid level height and wellbore pressure inside the wellbore. When the dynamic fluid level height inside the wellbore rises to the wellhead, proceed to Step 6. When the dynamic fluid level height inside the wellbore is within the well, the wellbore pressure is maintained within the formation pressure window range during the injection process.

[0022] Step 11, Well Workover Fluid Level Monitoring and Adaptive Injection: The control box controls the opening of the injection pump, thereby controlling the flow rate of the workover fluid, and injecting workover fluid into the wellbore. At the same time, the wellbore pressure is collected by the wellhead fluid level measuring instrument, so that the wellbore pressure is maintained within the formation pressure window range during the injection process.

[0023] The above-mentioned method for monitoring well workover fluid level and intelligent control of fluid injection is characterized in that: in step 602, the fixed time interval is 3 min to 5 min; and the number of tubing pipes pulled out each time is 3 to 5.

[0024] The above-mentioned method for monitoring well workover fluid level and intelligent control of fluid injection is characterized in that: in step 603, the number of continuing to run oil tubing is 1 to 3, and the detection time interval of the wellhead fluid level measuring instrument is 10 min to 30 min.

[0025] The above-mentioned method for monitoring well workover fluid level and intelligent control of injection is characterized in that: in step seven, the fixed time interval is 3 min to 5 min; and the value of N ranges from 8 to 15.

[0026] The above-mentioned method for monitoring well workover fluid level and intelligent control of injection is characterized in that: the control box includes a box body and an electronic circuit board installed in the box body, the electronic circuit board integrates a microcontroller and a communication module connected to the microcontroller; the installation valve and the injection pump are both controlled by the microcontroller, and the signal output terminal of the wellhead fluid level measuring instrument is connected to the input terminal of the microcontroller.

[0027] The above-mentioned method for monitoring well workover fluid level and intelligent control of fluid injection is characterized in that: the communication module includes a wired communication module and a wireless communication module; the microcontroller communicates with the industrial control computer through the wired communication module or the wireless communication module; the microcontroller communicates with the mobile monitoring terminal through the wireless communication module; the wired communication module includes an RS485 communication module; and the wireless communication module includes a WIFI wireless communication module and a GPRS wireless communication module.

[0028] The above-mentioned method for monitoring well workover fluid level and intelligent control of fluid injection is characterized in that: the housing is equipped with an alarm light connected to the microcontroller and used to display the fluid injection status.

[0029] Compared with the prior art, the present invention has the following advantages:

[0030] 1. This invention determines whether the dynamic fluid level is at the wellhead. When the wellhead fluid level measuring instrument detects that the dynamic fluid level inside the wellbore is at the wellhead, it controls the injection by using the well workover tubing and fluid injection. When the wellhead fluid level measuring instrument detects that the dynamic fluid level inside the wellbore is inside the well, it calculates the change in the dynamic fluid level inside the wellbore and adaptively injects fluid, thus achieving automatic fluid injection control under multiple working conditions.

[0031] 2. This invention calculates the height of the dynamic fluid level change within the wellbore to determine whether the height is negative. When the height is non-negative, it indicates no fluid level rise, the fluid column pressure in the well is balanced with the formation pressure, the injection pump does not operate, and there is no need to inject workover fluid into the wellbore. When the height is negative, it indicates fluid level rise, the fluid column pressure in the well is lower than the formation pressure, and timely injection of fluid is needed to control the formation pressure. When the fluid level rise speed is at the secondary level, workover fluid level monitoring and rapid injection are performed. When the fluid level rise speed is at the primary level, workover fluid level monitoring and adaptive injection are performed. This method is reliable, stable, and effective.

[0032] 3. The method of this invention has simple steps, strictly implements high-density injection, adjusts the injection system in a timely manner according to changes in the liquid level, performs precise injection, realizes intelligent injection control, ensures stable liquid column height in the wellbore, ensures balance between the liquid column pressure in the wellbore and the formation pressure, timely controls leakage and prevents well blowout, monitors changes in the wellbore liquid level in real time, continuously and accurately, realizes one control per well, and is easy to promote and use.

[0033] In summary, this invention achieves intelligent injection control by real-time monitoring of formation pressure changes within a window range, enabling timely adaptive grouting. It also requires controlling fluid upwelling velocity, strictly adhering to high-density injection, and adjusting the injection regime according to fluid level changes for precise injection. This ensures stable fluid column height within the wellbore, maintains balance between fluid column pressure and formation pressure, promptly controls leakage, and prevents blowouts. Real-time, continuous, and accurate monitoring of wellbore fluid level changes allows for individual well-specific control, providing effective technical support for effective plugging and well control safety, and facilitating widespread application.

[0034] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the intelligent control system for well workover fluid level monitoring and injection of the present invention.

[0036] Figure 2 This is a flowchart of the method of the present invention.

[0037] Explanation of reference numerals in the attached figures:

[0038] 1—Oil well casing; 2—Well casing branch pipe; 3—Installation valve;

[0039] 4—Wellhead fluid level gauge; 5—Blowout preventer; 6—Overflow preventer;

[0040] 7—Well sealing device; 8—Injection pool; 9—Injection pipe;

[0041] 10—Injection pump; 11—Workover fluid; 12—Control box. Detailed Implementation

[0042] like Figures 1 to 2 As shown, the present invention provides a method for monitoring well workover fluid levels and intelligent control of injection, comprising the following steps:

[0043] Step 1: Establish a well workover fluid level monitoring and injection intelligent control system. The well workover fluid level monitoring and injection intelligent control system includes a wellhead fluid level measuring instrument 4 installed on the wellbore branch pipe 2 of the oil wellbore 1 for detecting the dynamic fluid level height and wellbore pressure in the oil wellbore 1, and an injection pool 8 for injecting workover fluid 11 into the oil wellbore 1. A blowout preventer 5, an overflow preventer 6, and a well sealer 7 are installed sequentially on the top of the oil wellbore 1. One end of the injection pipe 9 is connected to the injection pool 8, and the other end of the injection pipe 9 extends into the oil wellbore 1 by passing sequentially through the well sealer 7, the overflow preventer 6, and the blowout preventer 5. The wellhead fluid level measuring instrument 4 is installed on the wellbore branch pipe 2 through an installation valve 3. An injection pump 10 is installed on the section of the injection pipe 9 located on the ground. Both the installation valve 3 and the injection pump 10 are controlled by a control box 12 on the ground. The signal output terminal of the wellhead fluid level measuring instrument 4 is connected to the input terminal of the control box 12.

[0044] Step 2: Set the formation pressure window range;

[0045] Step 3: Classify the velocity levels of formation pressure on the fluid surface within the window range: Classify the velocity levels of formation pressure on the fluid surface within the window range according to the velocity of formation pressure on the fluid surface. The velocity levels of formation pressure on the fluid surface within the window range include primary velocity and secondary velocity, and the primary velocity is less than the secondary velocity.

[0046] When the velocity v0 of the formation pressure on the surface of the dynamic fluid within the window is less than the threshold velocity of the dynamic fluid, the velocity v0 of the formation pressure on the surface of the dynamic fluid within the window is considered to be a first-order dynamic fluid surface velocity.

[0047] When the velocity v0 of the formation pressure on the surface of the dynamic fluid within the window is not less than the threshold velocity of the dynamic fluid surface, the velocity v0 of the formation pressure on the surface of the dynamic fluid within the window is a secondary velocity of the dynamic fluid surface.

[0048] Step 4: Use a wellhead fluid level measuring instrument to collect the dynamic fluid level height and wellbore pressure inside the oil well;

[0049] Step 5: Determine if the dynamic fluid level is at the wellhead. If the wellhead fluid level measuring instrument detects that the dynamic fluid level inside the wellbore is at the wellhead, proceed to Step 6; if the wellhead fluid level measuring instrument detects that the dynamic fluid level inside the wellbore is inside the well, proceed to Step 7.

[0050] Step Six: Well workover, tubing removal, and fluid injection, the process is as follows:

[0051] Step 601: Set the dynamic liquid level height range;

[0052] Step 602: Pull out the tubing multiple times at fixed time intervals. The number of tubing sections pulled out each time is fixed. Each time the tubing is pulled out, use the wellhead fluid level measuring instrument 4 to detect the dynamic fluid level height inside the wellbore once, until the current dynamic fluid level height is within the dynamic fluid level height range.

[0053] Step 603: Continue pulling in the tubing and use the wellhead fluid level gauge 4 to detect the dynamic fluid level in the wellbore. If the current dynamic fluid level is maintained within the dynamic fluid level range, the injection pump 10 does not work, and there is no need to add workover fluid 11 to the wellbore 1. If the current dynamic fluid level is below the dynamic fluid level range, add workover fluid 11 to the wellbore 1 to maintain the current dynamic fluid level within the dynamic fluid level range.

[0054] Step 604: Repeat step 603 multiple times until the oil pipe is lifted M times in a row and the dynamic fluid level shows an upward trend, then end the oil pipe lifting process.

[0055] Step 7: Calculate the dynamic fluid level change height inside the oil wellbore: Use the wellhead fluid level measuring instrument 4 to detect the dynamic fluid level height inside the oil wellbore N times at fixed time intervals, and calculate the change height according to the formula. Calculate the height h of the dynamic fluid level inside the wellbore during this exploration process. 1 Where n is the number of times the dynamic fluid level height inside the oil wellbore was detected during this exploration, N is the total number of times the dynamic fluid level height inside the oil wellbore was detected during this exploration, and h n This refers to the height of the dynamic fluid level inside the wellbore during the nth detection in this exploration process.

[0056] According to the formula Δh=h 1 -h 0 Calculate the height Δh of the dynamic fluid level change within the oil wellbore, where h 0 The height of the dynamic fluid level inside the wellbore obtained during the previous exploration process;

[0057] Step 8: Determine if the change in dynamic fluid level Δh in the wellbore is negative: When the change in dynamic fluid level Δh in the wellbore is non-negative, the injection pump 10 does not work, and there is no need to add workover fluid 11 to the wellbore 1; when the change in dynamic fluid level Δh in the wellbore is negative, proceed to step 9.

[0058] Step 9: Determine whether the formation pressure velocity v0 on the hydrodynamic surface within the window range belongs to the second-order hydrodynamic surface velocity: According to the formula... Calculate the formation pressure surface velocity v0 within the window interval, where T is the total time of this detection process. When the formation pressure surface velocity v0 within the window interval is not less than the surface velocity threshold, the formation pressure surface velocity v0 within the window interval belongs to the second-level surface velocity, and proceed to step ten; otherwise, proceed to step eleven.

[0059] Step 10, Well Workover Fluid Level Monitoring and Rapid Fluid Injection: Control box 12 controls injection pump 10 to fully open and inject workover fluid 11 into the wellbore 1. At the same time, the wellhead fluid level measuring instrument 4 is used to collect the dynamic fluid level height and wellbore pressure inside the wellbore. When the dynamic fluid level height inside the wellbore rises to the wellhead, step six is ​​executed. When the dynamic fluid level height inside the wellbore is within the well, the wellbore pressure is maintained within the formation pressure window range during the injection process.

[0060] Step 11, Well Workover Fluid Level Monitoring and Adaptive Fluid Injection: Control box 12 controls the opening of injection pump 10, thereby controlling the flow rate of well workover fluid, and injecting well workover fluid 11 into the wellbore 1. At the same time, the wellhead fluid level measuring instrument 4 is used to collect the wellbore pressure in the wellbore, so that the wellbore pressure is maintained within the formation pressure window range during the injection process.

[0061] In this embodiment, in step 602, the fixed time interval is 3 min to 5 min; and the number of oil pipes used each time is 3 to 5.

[0062] In this embodiment, in step 603, the number of oil-pulling pipes is 1 to 3, and the detection time interval of the wellhead fluid level measuring instrument 4 is 10 min to 30 min.

[0063] In this embodiment, in step seven, the fixed time interval is 3 min to 5 min; the value of N ranges from 8 to 15.

[0064] In this embodiment, the control box 12 includes a box body and an electronic circuit board disposed in the box body. The electronic circuit board integrates a microcontroller and a communication module connected to the microcontroller. The installation valve 3 and the injection pump 10 are both controlled by the microcontroller, and the signal output terminal of the wellhead liquid level measuring instrument 4 is connected to the input terminal of the microcontroller.

[0065] In this embodiment, the communication module includes a wired communication module and a wireless communication module. The microcontroller communicates with the industrial control computer through the wired communication module or the wireless communication module. The microcontroller communicates with the mobile monitoring terminal through the wireless communication module. The wired communication module includes an RS485 communication module, and the wireless communication module includes a WIFI wireless communication module and a GPRS wireless communication module.

[0066] In this embodiment, the box is equipped with an alarm light that is connected to the microcontroller and is used to display the filling status.

[0067] In use, this invention determines whether the dynamic fluid level is at the wellhead. When the wellhead fluid level measuring instrument detects that the dynamic fluid level inside the wellbore is at the wellhead, control is achieved using the workover tubing and injection fluid. When the wellhead fluid level measuring instrument detects that the dynamic fluid level inside the wellbore is inside the well, the change in the dynamic fluid level inside the wellbore is calculated, and adaptive injection fluid is applied to achieve automatic injection fluid control under multiple operating conditions. By calculating the change in the dynamic fluid level inside the wellbore, it is determined whether the change in the dynamic fluid level inside the wellbore is negative: when the change in the dynamic fluid level inside the wellbore is non-negative, it indicates that the fluid level has not risen, the fluid column pressure inside the well is balanced with the formation pressure, the injection pump does not work, and there is no need to add workover fluid to the wellbore; when the change in the dynamic fluid level inside the wellbore is negative, it indicates that the fluid level has risen, and the fluid column pressure inside the well is low. To control formation pressure, timely hydraulic injection is required. When the dynamic fluid surface rise velocity is at the secondary level, well workover fluid level monitoring and rapid injection are implemented. When the dynamic fluid surface rise velocity is at the primary level, well workover fluid level monitoring and adaptive injection are implemented. By monitoring the dynamic fluid level changes within the formation pressure window in real time, timely adaptive injection is carried out. At the same time, it is necessary to control the fluid rise velocity, strictly implement high-density injection, and adjust the injection regime in a timely manner according to fluid level changes to achieve precise injection and realize intelligent injection control. This ensures the stability of the fluid column height in the wellbore, guarantees the balance between the fluid column pressure in the wellbore and the formation pressure, timely controls leakage and prevents well blowouts, and monitors wellbore fluid level changes in real time, continuously and accurately, achieving one control per well. This provides effective technical support for effective plugging and well control safety.

[0068] The wellbore fluid level monitoring uses infrasound of a specific spectrum to propagate and reflect in the wellbore annulus or water eye, and performs frequency domain signal processing. It uses a unique sound velocity calculation model and wellbore fluid level calculation model to perform real-time accurate and stable calculations. The wellhead fluid level measuring instrument 4 adopts the integrated oil well dynamic fluid level measuring device disclosed in patent number 20172039520.4. The control box 12 identifies the pre-processed dynamic fluid level data through the invention patent "A Method for Identifying Dynamic Fluid Level in Oil Wells" disclosed in patent number 201810168944.8 to obtain accurate dynamic fluid level depth results and casing pressure values.

[0069] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the present invention. Any simple modifications, alterations, or equivalent structural changes made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A method for monitoring well workover fluid level and intelligent control of injection, characterized in that, The method includes the following steps: Step 1: Establish a well workover fluid level monitoring and injection intelligent control system. The well workover fluid level monitoring and injection intelligent control system includes a wellhead fluid level measuring instrument (4) installed on the wellbore branch pipe (2) of the oil wellbore (1) for detecting the dynamic fluid level height and wellbore pressure in the oil wellbore (1), and an injection pool (8) for injecting workover fluid (11) into the oil wellbore (1). A blowout preventer (5), an overflow preventer (6), and a well sealer (7) are installed in sequence on the top of the oil wellbore (1). One end of the injection pipe (9) is connected to the injection pool. The pool (8) is connected, and the other end of the injection pipe (9) extends into the wellbore (1) through the well sealer (7), the overflow pipe (6) and the blowout preventer (5) in sequence. The wellhead fluid level measuring instrument (4) is installed on the wellbore branch pipe (2) through the installation valve (3). The injection pump (10) is installed on the pipe section of the injection pipe (9) located on the ground. The installation valve (3) and the injection pump (10) are both controlled by the control box (12) on the ground. The signal output end of the wellhead fluid level measuring instrument (4) is connected to the input end of the control box (12). Step 2: Set the formation pressure window range; Step 3: Classify the velocity levels of formation pressure on the fluid surface within the window range: Classify the velocity levels of formation pressure on the fluid surface within the window range according to the velocity of formation pressure on the fluid surface. The velocity levels of formation pressure on the fluid surface within the window range include primary velocity and secondary velocity, and the primary velocity is less than the secondary velocity. When the velocity v0 of the formation pressure on the surface of the dynamic fluid within the window is less than the threshold velocity of the dynamic fluid, the velocity v0 of the formation pressure on the surface of the dynamic fluid within the window is considered to be a first-order dynamic fluid surface velocity. When the velocity v0 of the formation pressure on the surface of the dynamic fluid within the window is not less than the threshold velocity of the dynamic fluid surface, the velocity v0 of the formation pressure on the surface of the dynamic fluid within the window is a secondary velocity of the dynamic fluid surface. Step 4: Use a wellhead fluid level measuring instrument to collect the dynamic fluid level height and wellbore pressure inside the oil well; Step 5: Determine if the dynamic fluid level is at the wellhead. If the wellhead fluid level measuring instrument detects that the dynamic fluid level inside the wellbore is at the wellhead, proceed to Step 6; if the wellhead fluid level measuring instrument detects that the dynamic fluid level inside the wellbore is inside the well, proceed to Step 7. Step Six: Well workover, tubing removal, and fluid injection, the process is as follows: Step 601: Set the dynamic liquid level height range; Step 602: Pull out the tubing multiple times at fixed time intervals. The number of tubing pulled out each time is fixed. Each time the tubing is pulled out, use the wellhead fluid level measuring instrument (4) to detect the dynamic fluid level height in the wellbore once until the current dynamic fluid level height is within the dynamic fluid level height range. Step 603: Continue to run the tubing and use the wellhead fluid level measuring instrument (4) to detect the dynamic fluid level in the wellbore. If the current dynamic fluid level is maintained within the dynamic fluid level range, the injection pump (10) will not work and there is no need to inject workover fluid (11) into the wellbore (1). If the current dynamic fluid level is below the dynamic fluid level range, inject workover fluid (11) into the wellbore (1) to maintain the current dynamic fluid level within the dynamic fluid level range. Step 604: Repeat step 603 multiple times until the oil pipe is lifted M times in a row and the dynamic fluid level shows an upward trend, then end the oil pipe lifting process. Step 7: Calculate the height of the dynamic fluid level change in the wellbore: Use a wellhead fluid level measuring instrument (4) to detect the height of the dynamic fluid level in the wellbore N times at fixed time intervals, and calculate the height according to the formula. Calculate the height h of the dynamic fluid level inside the wellbore during this exploration process. 1 Where n is the number of times the dynamic fluid level height inside the oil wellbore was detected during this exploration, N is the total number of times the dynamic fluid level height inside the oil wellbore was detected during this exploration, and h n This refers to the height of the dynamic fluid level inside the wellbore during the nth detection in this exploration process. According to the formula Δh=h 1 -h 0 Calculate the height Δh of the dynamic fluid level change within the oil wellbore, where h 0 The height of the dynamic fluid level inside the wellbore obtained during the previous exploration process; Step 8: Determine if the change in dynamic fluid level Δh in the wellbore is negative: When the change in dynamic fluid level Δh in the wellbore is non-negative, the injection pump (10) does not work and there is no need to inject workover fluid (11) into the wellbore (1); when the change in dynamic fluid level Δh in the wellbore is negative, proceed to step 9. Step 9: Determine whether the formation pressure velocity v0 on the hydrodynamic surface within the window range belongs to the second-order hydrodynamic surface velocity: According to the formula... Calculate the formation pressure surface velocity v0 within the window interval, where T is the total time of this detection process. When the formation pressure surface velocity v0 within the window interval is not less than the surface velocity threshold, the formation pressure surface velocity v0 within the window interval belongs to the second-level surface velocity, and proceed to step ten; otherwise, proceed to step eleven. Step 10, Well Workover Fluid Level Monitoring and Rapid Fluid Injection: The control box (12) controls the injection pump (10) to be fully opened to inject well workover fluid (11) into the wellbore (1). At the same time, the wellhead fluid level measuring instrument (4) is used to collect the dynamic fluid level height and wellbore pressure in the wellbore. When the dynamic fluid level height in the wellbore rises to the wellhead, step six is ​​executed. When the dynamic fluid level height in the wellbore is within the well, the wellbore pressure is maintained within the formation pressure window range during the injection process. Step 11, Well Workover Fluid Level Monitoring and Adaptive Fluid Injection: The control box (12) controls the opening of the injection pump (10), thereby controlling the flow rate of the well workover fluid, and injecting the well workover fluid (11) into the wellbore (1). At the same time, the wellbore pressure in the wellbore is collected by the wellhead fluid level measuring instrument (4), so that the wellbore pressure is maintained within the formation pressure window range during the injection process.

2. The method for monitoring well workover fluid level and intelligent control of injection fluid according to claim 1, characterized in that: In step 602, the fixed time interval is 3 to 5 minutes; the number of oil pipes used each time is 3 to 5.

3. The method for monitoring well workover fluid level and intelligent control of injection fluid according to claim 1, characterized in that: In step 603, the number of oil-pulling pipes is 1 to 3, and the detection time interval of the wellhead fluid level measuring instrument (4) is 10 min to 30 min.

4. The method for monitoring well workover fluid level and intelligent control of injection fluid according to claim 1, characterized in that: In step seven, the fixed time interval is 3 min to 5 min; the value of N ranges from 8 to 15.

5. The method for monitoring well workover fluid level and intelligent control of injection fluid according to claim 1, characterized in that: The control box (12) includes a box body and an electronic circuit board installed inside the box body. The electronic circuit board integrates a microcontroller and a communication module connected to the microcontroller. The installation valve (3) and the injection pump (10) are both controlled by the microcontroller. The signal output terminal of the wellhead liquid level measuring instrument (4) is connected to the input terminal of the microcontroller.

6. The method for monitoring well workover fluid level and intelligent control of injection fluid according to claim 5, characterized in that: The communication module includes a wired communication module and a wireless communication module. The microcontroller communicates with the industrial control computer through the wired communication module or the wireless communication module. The microcontroller communicates with the mobile monitoring terminal through the wireless communication module. The wired communication module includes an RS485 communication module. The wireless communication module includes a WIFI wireless communication module and a GPRS wireless communication module.

7. The method for monitoring well workover fluid level and intelligent control of injection fluid according to claim 5, characterized in that: The enclosure is equipped with an alarm light that is connected to the microcontroller and is used to display the filling status.

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