Blocking method for oil pipe of oil field and multi-drift-diameter throwing-pulling type blanking plug

Abstract

The invention relates to the technical field of oil field engineering, and discloses a multi-diameter throwing-pulling type blanking plug which comprises an upper connector, the outer side of the upper connector is in threaded connection with a lower connector, the inner side of the lower connector is fixedly connected with a degradable plugging base, the inner side of the lower connector is provided with a blanking plug mandrel, one end of the blanking plug mandrel is provided with a guide head, and the other end of the blanking plug mandrel is provided with a screw. An adjusting head is in threaded connection with a through hole in the outer surface of the blanking plug core shaft, a driving column is fixedly connected to the inner side of the adjusting head, and a fixing plate is fixedly connected to the interior of the blanking plug core shaft. The guide heads of various specifications are provided and can be quickly replaced, so that the same blanking plug can be suitable for different oil pipe drift diameters and operation requirements, and the tedious process of frequently replacing equipment or redeploying an operation device is avoided. By means of the design, the response speed and flexibility of operation are greatly improved, the shutdown time is shortened, and the overall efficiency of oil field operation is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of oilfield engineering, and particularly to a method for plugging oilfield tubing and a multi-diameter fishing plugging device. Background Art

[0002] During the oilfield exploitation process, the normal operation of the tubing is crucial. Oilfield tubing often gets blocked due to various factors, resulting in a decline in the production efficiency of oil wells and even production suspension. The main reasons for blockage include impurities in oil and gas (such as sand, cuttings, scale deposits), corrosion and deposition of oilfield water, and the deposition of substances such as paraffin and asphalt formed in high-temperature and high-pressure environments. These blockages accumulate in the tubing and, in severe cases, completely block the tubing, preventing the fluid from flowing smoothly and affecting the normal output of oil wells. The blockage problem not only increases the production difficulty and cost but also causes equipment damage and affects the safe production of oilfields.

[0003] To solve the tubing blockage problem, traditional plugging methods use physical plugging or mechanical cleaning and other means. Physical plugging generally relies on the delivery of plugging devices or plugging materials, which enter through the tubing and form a plugging layer at the required position. However, it is difficult to ensure the delivery accuracy and position of the plugging device, and due to the pressure imbalance inside and outside the tubing, the plugging device is prone to damage or displacement, and the plugging effect is difficult to guarantee.

[0004] In addition, traditional plugging devices often stay in the tubing for a long time, increasing the wear and corrosion of the pipeline and affecting the long-term use of the tubing. This long-term retention leads to increased corrosion of the inner wall of the pipeline and has an adverse effect on oil well equipment. More importantly, the existing technology lacks an effective control mechanism for the degradation and removal of plugging devices. Once the plugging device completes its plugging task, it cannot be degraded or removed in a timely manner, but instead increases the complexity and cost of oilfield maintenance. For this reason, those skilled in the art have proposed a method for plugging oilfield tubing and a multi-diameter fishing plugging device to solve the above problems. Summary of the Invention

[0005] In view of the deficiencies of the prior art, the present invention provides a method for plugging oilfield tubing and a multi-diameter fishing plugging device, which solves the problems raised in the above background art.

[0006] To achieve the above objectives, the present invention is realized through the following technical solutions: A method for plugging oilfield tubing includes the following steps:

[0007] S1. Connect the plugging device body to the tubing through threaded connection, and install the plugging device into the tubing according to the inner diameter of the tubing and position it at a predetermined position;

[0008] S2. Send the plugging assembly to the inside of the plugging body through a cable, ensure that the plugging assembly is firmly installed inside the degradable plugging base, and apply appropriate pressure to the upper and lower tubing spaces of the plugging device;

[0009] S3. Monitor the liquid pressure inside the plugging device in real time, obtain the pressure in the upper tubing space and the pressure in the lower tubing space, and calculate the actual pressure in the upper tubing space through the following formula:

[0010] Pup = ρgh

[0011] where Pup is the pressure in the upper tubing space, ρ is the density of the liquid, g is the acceleration due to gravity, and h is the height of the liquid;

[0012] S4. Based on the real-time monitoring results, judge the difference between the pressure in the lower tubing space and the pressure in the upper tubing space, and adjust the pressure in the upper tubing space according to the difference to make it meet the lower pressure adjustment requirements.

[0013] Preferably, the monitoring system further obtains the pressure in the lower tubing space in real time, and through the lower pressure calculation formula:

[0014] Pdown = ρdown.g.hdown

[0015] where PdowN is the pressure in the lower tubing space, ρdowN is the density of the lower liquid, and hdowN is the height of the liquid in the lower tubing space.

[0016] Preferably, in step S3, if the pressure Pdown in the lower tubing space is greater than the pressure Pup in the upper tubing space, a higher pressure is applied to the upper tubing space through the liquid injection control system until the predetermined pressure of the plugging device is reached, that is:

[0017] Pup,new = Pdown + ΔP

[0018] where ΔP is the differential compensation pressure.

[0019] Preferably, in step S4, the isolation layer of the degradable plugging base is damaged by applying an appropriate pressure to the upper tubing space, and the rupture pressure Pburst of the isolation layer is calculated by the following formula:

[0020]

[0021] where Pburst is the rupture pressure, Qflow is the oil and gas flow rate through the plugging base, Aseal is the surface area of the isolation layer, and Δt is the time difference for the oil and gas flow to pass through the plugging base.

[0022] Preferably, it further includes controlling the injection amount of the liquid in the upper tubing space through real-time monitoring and pressure regulation, and controlling the degradation rate of the plugging base isolation layer, where the degradation rate is controlled by the following model:

[0023]

[0024] Wherein, is the degradation rate of the plugging base isolation layer, κ is the degradation constant, τ is the degradation time constant, and t is the time.

[0025] Preferably, it further includes, after completing the plugging operation, pumping out the liquid in the upper tubing space through a liquid extraction system to reduce the pressure and remove the plugging device assembly, and this step is further controlled by the following formula:

[0026] Premove=Pup-ΔPext

[0027] Wherein, Premove is the pressure when removing the plugging device, and ΔPext is the external pressure adjustment amount.

[0028] Preferably, the S3 step further includes:

[0029] S31, if the pressure in the lower tubing is less than the pressure in the upper tubing, the system reduces the pressure in the upper tubing space through a liquid regulating device to make it close to the pressure in the lower tubing space, thereby avoiding damage to the plugging device caused by pressure imbalance;

[0030] S32, adjusting the pressure balance in the plugging device according to the pressure difference between the upper tubing space and the lower tubing space.

[0031] The multi-path fishing plugging device includes an upper joint, the outer side of the upper joint is threadedly connected with a lower joint, the inner side of the lower joint is fixedly connected with a degradable plugging base, the inner side of the lower joint is provided with a plugging device mandrel, one end of the plugging device mandrel is provided with a guide head, the outer surface through hole of the plugging device mandrel is threadedly connected with an adjusting head, the inner side of the adjusting head is fixedly connected with a driving column, the inside of the plugging device mandrel is fixedly connected with a fixing plate, the inside through hole of the fixing plate is slidably connected with a connecting column, one end of the connecting column is rotatably connected with two connecting rods, one end of the connecting rod is rotatably connected with a clamping column, and two clamping grooves are formed in the inside of the guide head.

[0032] Preferably, a spring is sleeved outside the clamping groove, one end of the spring is fixedly connected with the outside of the connecting column, and the other end of the spring is fixedly connected with the outside of the fixing plate.

[0033] Preferably, the cross-section of the clamping column is square, the end of the clamping column is inserted and matched with the inside of the clamping groove, and inclined surfaces are provided on one side of the connecting column and the bottom of the driving column.

[0034] The present invention provides a plugging method for oilfield tubing and a multi-diameter fishing plugging device, having the following beneficial effects:

[0035] 1. By precisely controlling the liquid pressure difference between the upper and lower tubing spaces, the present invention realizes the precise adjustment of the tubing plugging device and optimizes the plugging process. The pressure values of the upper and lower tubing spaces are obtained and calculated through a real-time monitoring system, and the flow rate and pressure of the injected liquid are adjusted according to the pressure difference, so as to ensure that the tubing plugging device can withstand the optimal operating pressure during plugging. This precise pressure control technology not only avoids the damage of the plugging device caused by pressure imbalance, but also effectively prevents liquid backflow or plugging device displacement during the plugging process, significantly improving the working stability and plugging effect of the plugging device, ensuring the long-term stable operation of the oilfield tubing, reducing the maintenance frequency and production downtime, and enhancing the economic benefits and operation safety of the oilfield.

[0036] 2. By applying an appropriate pressure to the upper tubing space and precisely controlling the degradation rate of the isolation layer of the plugging base, the oilfield tubing plugging method of the present invention can effectively prevent pipeline damage caused by the long-term presence of the plugging device in the tubing. In traditional plugging methods, the plugging device stays in the tubing for a long time, resulting in problems such as corrosion and wear, thus affecting the normal operation of oilfield equipment. However, the present invention ensures that the plugging device can rapidly degrade and be removed after completing the plugging task by real-time monitoring and adjusting the degradation rate, thereby reducing the risk of pipeline damage, extending the service life of oilfield production equipment, and enhancing operation safety.

[0037] 3. By providing guiding heads of various specifications and enabling quick replacement, the same plugging device can be applicable to different tubing diameters and operation requirements, avoiding the cumbersome process of frequently replacing equipment or redeploying operation devices. This design greatly improves the response speed and flexibility of operations, shortens the downtime, and enhances the overall efficiency of oilfield operations. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 is a perspective view of the present invention;

[0039] Figure 2 is a schematic structural view of the lower joint of the present invention;

[0040] Figure 3 is a schematic structural view of the guiding head of the present invention;

[0041] Figure 4 is a schematic structural view of the degradable plugging base of the present invention;

[0042] Figure 5 is a schematic structural view of the driving column of the present invention.

[0043] Among them, 1. upper joint; 2. lower joint; 3. plug mandrel; 4. guide head; 5. adjusting head; 6. biodegradable plugging base; 7. driving column; 8. connecting column; 9. card slot; 10. clamping column; 11. connecting rod; 12. fixing plate. Specific embodiments

[0044] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0045] Please refer to the attached Figure 1 -attached Figure 5 , and the embodiments of the present invention provide a method for plugging oilfield tubing, including the following steps:

[0046] S1. Connect the plug body to the tubing by threaded connection, and install the plug into the tubing according to the inner diameter of the tubing, and position it at a predetermined position;

[0047] Specifically, in the plugging operation of oilfield tubing, the first step is to physically connect the plug body to the tubing. In this case, the inner diameter of the tubing has a certain standardized design, so the outer diameter of the plug body needs to be selected according to the inner diameter of the tubing to ensure that the plug can be accurately installed into the tubing. This step is completed by threaded connection, which can provide sufficient sealing performance and mechanical stability to ensure that the plug body will not loosen or shift during subsequent operations. Through threaded connection, the plug body can be conveniently fixed at the designated position of the tubing. The position of the plug needs to be accurately positioned. After positioning to the predetermined position, the next operation stage can be entered.

[0048] S2. Send the plug assembly to the inside of the plug body through a cable, ensure that the plug assembly is firmly installed inside the biodegradable plugging base, and apply appropriate pressure to the tubing spaces above and below the plug; Specifically, in this step, the plug assembly (including the biodegradable plugging base, plugging material, etc.) needs to be sent in through a cable. Using a cable to send the plug assembly to the inside of the plug body is because the space inside the tubing is very narrow, and direct operation or installation of other equipment will be restricted by physical space. The use of a cable can effectively control the position and stability of the plug assembly to ensure its correct and stable installation. Inside the plug body, the plug assembly needs to be firmly installed inside the biodegradable plugging base. The biodegradable plugging base is one of the key designs of the present invention, which can be controlled to degrade under specific conditions to form a plugging effect on the tubing. This base can not only withstand a certain amount of pressure, but also ensure the stable operation of the plug within the predetermined service life.

[0049] S3. Monitor the liquid pressure in the plug in real time, obtain the pressure in the upper tubing space and the pressure in the lower tubing space, and calculate the actual pressure in the upper tubing space through the following formula:

[0050] Pup = ρgh

[0051] where Pup is the pressure in the upper tubing space, ρ is the density of the liquid, g is the acceleration due to gravity, and h is the height of the liquid;

[0052] Specifically, real-time monitoring of the liquid pressure in the plug is one of the important links of this method. The pressure in the tubing is crucial for the normal operation of the plugging device. Excessive or too low pressure will affect the function of the plugging device, even leading to plugging failure or equipment damage. Therefore, during the plugging operation, it is necessary to accurately measure the liquid pressure in the plug to ensure the plugging effect of the tubing. Through the above formula, the actual pressure in the upper tubing space can be calculated. In practical applications, factors such as the pressure difference between the inside and outside of the plug, the depth of the tubing, and the properties of the liquid will affect the pressure value. Therefore, it is necessary to continuously adjust the working state of the plug according to the real-time monitoring data to ensure the stability of the plugging effect.

[0053] Step S3 further includes:

[0054] S31. If the pressure in the lower tubing is less than the pressure in the upper tubing, the system reduces the pressure in the upper tubing space through the liquid regulating device to make it close to the pressure in the lower tubing space, thus avoiding damage to the plug caused by pressure imbalance;

[0055] Specifically, the reasons and risks of pressure imbalance: During the normal operation of oilfield tubing, due to factors such as oil and gas flow, temperature change, and liquid column height, different pressures will be generated in the upper and lower spaces of the tubing. If the pressure in the upper tubing space is higher than the pressure in the lower tubing space, it will cause the plug (or similar equipment) to be subjected to uneven external forces, resulting in damage or ineffective operation. The function of the liquid regulating device: The liquid regulating device is a key equipment, which realizes the balance of the upper and lower tubing pressures by adjusting the liquid pressure inside the tubing. By reducing the pressure in the upper tubing space, the liquid regulating device can reduce it to be close to the pressure in the lower tubing space, thus avoiding plug damage or other equipment failures caused by excessive pressure difference. The liquid regulating device adjusts the pressure by injecting or discharging liquid. For example, by releasing a part of the liquid or injecting gas or liquid mixture to balance the pressure in the upper and lower tubing spaces, ensuring that the plug can work normally within a reasonable pressure range. The core purpose of this operation is to avoid overload or damage of the plug components due to too high or too low pressure, thereby extending the equipment life and ensuring the smooth progress of the plugging operation.

[0056] S32. Adjust the pressure balance inside the plug according to the pressure difference between the upper tubing space and the lower tubing space.

[0057] Specifically, the system will monitor the pressure difference between the upper and lower tubing spaces in real time. When the difference exceeds a predetermined range, the regulating device will be activated to adjust the pressure inside the plug. The adjustment process involves an automated control system that adjusts the pressure by means such as liquid delivery or discharge, gas control, etc. Specifically, the internal and external pressure difference of the plug will be adjusted to ensure that the plug can effectively perform the plugging operation.

[0058] S4. Based on the real-time monitoring results, judge the difference between the pressure in the lower tubing space and the pressure in the upper tubing space, and adjust the pressure in the upper tubing space according to the difference to make it meet the lower pressure regulation requirements.

[0059] In step S4, the isolation layer of the degradable plugging base is damaged by applying an appropriate pressure to the upper tubing space. The rupture pressure Pburst of the isolation layer is calculated by the following formula:

[0060]

[0061] Where Pburst is the rupture pressure, that is, the pressure required for the isolation layer to rupture. The rupture pressure is a key parameter affecting whether the plugging base can rupture smoothly and is the minimum pressure value for effectively rupturing the isolation layer of the plugging base. Qflow is the oil and gas flow rate flowing through the plugging base. The flow rate reflects the amount of oil and gas passing through this area and is the fluid volume per unit time. The magnitude of the flow rate directly affects the pressure borne by the isolation layer.

[0062] Therefore, when the flow rate is larger, a higher rupture pressure is required. Aseal is the surface area of the isolation layer, which refers to the surface area of the isolation layer of the plugging base that directly contacts the oil and gas flow. The larger the surface area, the higher the pressure required for rupture because a larger contact area means a larger stress distribution. Δt is the time difference of the oil and gas flow rate flowing through the plugging base. The time difference is the duration for the fluid to pass through the plugging base. The longer the time difference, the more obvious the pressure accumulation of the unit flow rate on the isolation layer. Therefore, the longer the time difference for the oil and gas to flow through the plugging base, the higher the rupture pressure needs to be to overcome the resistance of the isolation layer.

[0063] Specifically, in practical applications, by real-time monitoring the pressure difference between the lower tubing space and the upper tubing space, it can be determined whether it is necessary to adjust the pressure in the upper tubing space. For example, if the pressure in the lower tubing space is higher than the pressure in the upper tubing space, it is necessary to adjust the pressure in the upper tubing space to avoid excessive compression or rupture of the system.

[0064] During specific implementation, the system will maintain an appropriate pressure difference by adjusting the pressure in the upper tubing space according to the monitored pressure difference, so that the pressure difference remains within a safe range, ensuring that the plugging base can rupture as expected. Additionally, by controlling the oil and gas flow rate, monitoring the surface area and flow-through time of the plugging base, the adjustment process of the rupture pressure can be further refined, thus optimizing the rupture performance of the plugging base.

[0065] The monitoring system further obtains the pressure in the lower tubing space in real time and uses the following formula for calculating the lower pressure:

[0066] Pdown = ρdown.g.hdown

[0067] where Pdown is the pressure in the lower tubing space, with the unit of Pascal (Pa), ρdown is the density of the lower liquid, with the unit of kilogram per cubic meter (kg / m 3 ), and hdown is the height of the liquid in the lower tubing space. This parameter represents the column height of the liquid in the tubing space and is measured in real time by a liquid level sensor.

[0068] Specifically, the monitoring system of the present invention includes: a pressure sensor, a liquid density sensor, a liquid height sensor, and a data calculation module. The specific working principle is as follows:

[0069] Pressure sensor: Obtains the pressure data in the lower tubing space in real time as the initial input of the monitoring system.

[0070] Liquid density sensor: Measures the density of the liquid in the tubing in real time. The liquid density varies with factors such as temperature and salinity, so its accurate measurement is crucial for subsequent pressure calculations.

[0071] Liquid height sensor: Measures the height of the liquid in the tubing space in real time.

[0072] The monitoring system feeds back the calculation results to the operator through a display device, an alarm device, or a remote control system, so as to adjust the mining process in a timely manner and ensure the safety of equipment and personnel.

[0073] The advantages of this technical solution are as follows:

[0074] High-precision monitoring: Through real-time monitoring of liquid density and liquid height, combined with a simple physical formula, the pressure in the lower tubing space can be accurately calculated, avoiding the defect that traditional pressure sensors are easily affected by environmental interference.

[0075] Real-time feedback: The monitoring system calculates the pressure in real time and outputs data, which can immediately reflect the pressure changes inside the tubing, helping the operator quickly judge the operating state of the equipment.

[0076] Improve safety: Accurate pressure monitoring can prevent damage to equipment caused by excessive or too low pressure, thereby reducing safety risks during the mining process.

[0077] Simplify the system structure: By calculating pressure based on liquid density and liquid height, the present invention reduces the dependence on high-complexity and expensive pressure sensors, and reduces the overall cost of the system.

[0078] In step S3, if the pressure Pdown in the lower tubing space is greater than the pressure Pup in the upper tubing space, a higher pressure is applied to the upper tubing space through the liquid injection control system until the predetermined pressure of the plug is reached, that is:

[0079] Pup, new = Pdown + ΔP

[0080] where ΔP is the differential compensation pressure.

[0081] It also includes controlling the injection amount of the liquid in the upper tubing space through real-time monitoring and pressure regulation, and controlling the degradation rate of the plugging base isolation layer, where the degradation rate is controlled by the following model:

[0082]

[0083] where is the degradation rate of the plugging base isolation layer, κ is the degradation constant, τ is the degradation time constant, and t is the time.

[0084] It also includes, after completing the plugging operation, pumping out the liquid in the upper tubing space through the liquid extraction system to reduce the pressure and remove the plug assembly, and this step is further controlled by the following formula:

[0085] Premove = Pup - ΔPext

[0086] where Premove is the pressure when removing the plug, which is a target pressure, lower than the original working pressure of the system, so as to be able to smoothly remove the plug. Pup is the pressure in the upper tubing space, that is, the original pressure in the system before pumping out the liquid, and ΔPext represents the pressure change amount applied through external operations or equipment. This adjustment amount can be adjusted through external means such as the liquid extraction system and the gas regulation device to reduce the pressure in the upper tubing space, thereby reducing the pressure required to remove the plug.

[0087] Specifically, this section introduces the importance of pressure regulation in the process of removing the plug. Excessive pressure makes it difficult to remove the plug and may even cause damage to the equipment or pipeline. Therefore, by precisely controlling the pressure, it is ensured that the pressure when removing the plug is appropriate, improving the safety and efficiency of the operation.

[0088] By external pressure regulation (ΔP_ext), the pressure inside the pipeline can be reduced, and the removal process can be made more controllable, avoiding problems caused by pressure fluctuations or excessive pressure differences when removing the plug

[0089] The multi-diameter fishing plug includes an upper joint 1. The outer side of the upper joint 1 is threadedly connected to a lower joint 2. The inner side of the lower joint 2 is fixedly connected to a biodegradable plugging base 6. A plug core shaft 3 is arranged inside the lower joint 2. One end of the plug core shaft 3 is provided with a guide head 4. A regulating head 5 is threadedly connected to the through hole on the outer surface of the plug core shaft 3. The inner side of the regulating head 5 is fixedly connected to a driving column 7. A fixing plate 12 is fixedly connected inside the plug core shaft 3. A connecting column 8 is slidably connected to the through hole inside the fixing plate 12. One end of the connecting column 8 is rotatably connected to two connecting rods 11. One end of the connecting rods 11 is rotatably connected to a clamping column 10. Two clamping grooves 9 are formed inside the guide head 4

[0090] Specifically, the lower joint 2 is threadedly connected to the upper joint 1 through its outer side and belongs to a part of the connecting device. Its inner side is fixedly connected to a biodegradable plugging base 6. The function of this base is to help the plug degrade or be disassembled conveniently after use. The plug core shaft 3 is the main component of the plug, used to transmit force and maintain structural stability. The guide head 4 is located at the front end of the plug, helping the plug to be better guided and positioned in the oil pipe to ensure that it can operate precisely. The fixing plate 12 is fixed inside the plug core shaft 3, playing a role in supporting and holding the connecting column 8. The fixing plate 12 is connected to the connecting rod 11 through the connecting column 8, helping to coordinate the movement between components. The clamping grooves 9 are located inside the guide head 4, used to receive the clamping column 10. When the clamping column 10 is clamped into the clamping groove 9, the guide head 4 is fixed in place to ensure its stable operation

[0091] Installing the guide head 4:

[0092] First, by rotating the regulating head 5, the regulating head 5 moves downward along the threaded hole on the outer surface of the plug core shaft 3. The downward movement of the regulating head 5 drives the driving column 7 downward. The inclined surface of the driving column 7 contacts the inclined surface of the connecting column 8. Due to the contact force, the connecting column 8 starts to move along the inner cavity of the plug core shaft 3. The movement of the connecting column 8 compresses the fixing plate 12 and drives the connecting rod 11 connected to its end to swing. Through the traction force of the connecting rod 11, the clamping column 10 enters the clamping groove 9 inside the guide head 4, thus completing the installation of the guide head 4

[0093] Removing the guide head 4:

[0094] When removal is required, only rotate the regulating head 5 in the opposite direction. Due to the action of the spring, the connecting column 8 will reset, driving the clamping column 10 to separate from the clamping groove 9. At this time, the guide head 4 can be removed from the plug

[0095] One end of the spring is fixedly connected to the outside of the connecting column 8, and the other end of the spring is fixedly connected to the outside of the fixing plate 12. The cross-section of the clamping post 10 is square, and the end of the clamping post 10 is inserted and matched with the inner side of the clamping groove 9. Bevels are provided on one side of the connecting column 8 and the bottom of the driving column 7.

[0096] Specifically, the spring plays a very important role in this structure. One end of the spring is fixedly connected to the outside of the connecting column 8, and the other end is fixedly connected to the outside of the fixing plate 12. The spring is used to provide a restoring force so that the plug can be maintained at a certain position in the initial state. The cross-section of the clamping post 10 is square, aiming to provide better clamping stability. The square cross-sectional shape enables it to be firmly embedded or clamped in the specific clamping groove 9, preventing unnecessary movement of the components of the plug during operation. The square design can not only enhance the rigidity of the structure but also simplify the installation and disassembly process.

[0097] Working principle: The operating principle of the multi-diameter fishing plug is as follows:

[0098] When the guide head 4 needs to be installed, first rotate the adjusting head 5 to make the adjusting head 5 move downward along the threaded hole on the outer surface of the plug core shaft 3, further driving the driving column 7 to move downward. At this time, the bevel at the bottom end of the driving column 7 contacts the bevel on the outer surface of the connecting column 8. At this time, the connecting column 8 will move along the inner cavity of the plug core shaft 3. While the connecting column 8 is moving, it will drive the fixing plate 12 to be in a compressed state. At this time, as the connecting column 8 moves, it will drive the two connecting rods 11 connected to its end to swing. At this time, under the traction force of the connecting rods 11, the clamping post 10 is clamped into the clamping groove 9 inside the guide head 4, thus quickly completing the installation of the guide head 4. Similarly, when the guide head 4 needs to be disassembled, only need to rotate the adjusting head 5 in the reverse direction, and the connecting column 8 is reset under the action of the spring. At this time, the end of the clamping post 10 separates from the inside of the clamping groove 9, thus completing the quick replacement of the guide head 4. By providing guide heads 4 of various specifications and being able to quickly replace them, the same plug can be applied to different tubing diameters and operation requirements, avoiding the cumbersome process of frequently replacing equipment or redeploying the operation device. This design greatly improves the response speed and flexibility of the operation, shortens the downtime, and improves the overall efficiency of oilfield operations.

[0099] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for blocking an oilfield tubing, characterized in that, It includes the following steps: S1. Connect the plug body to the oil pipe by threaded connection, install the plug into the oil pipe according to the inner diameter of the oil pipe, and position it at a predetermined position; S2. Send the plug assembly to the inside of the plug body through a cable, ensure that the plug assembly is firmly installed inside the degradable plugging base, and apply appropriate pressure to the upper and lower oil pipe spaces of the plug; S3. Monitor the liquid pressure inside the plug in real time, obtain the pressure of the upper oil pipe space and the pressure of the lower oil pipe space, and calculate the actual pressure of the upper oil pipe space through the following formula: Pup = ρgh Where, Pup is the pressure of the upper oil pipe space, ρ is the density of the liquid, g is the acceleration due to gravity, and h is the height of the liquid; S4. Based on the real-time monitoring results, judge the difference between the pressure of the lower oil pipe space and the pressure of the upper oil pipe space, and adjust the pressure of the upper oil pipe space according to the difference to make it meet the lower pressure adjustment requirements.

2. The plugging method for an oilfield tubing according to claim 1, characterized in that, The monitoring system further obtains the pressure of the lower oil pipe space in real time and passes it through the lower pressure calculation formula: Pdown = ρdowN.g.hdown Where, PdowN is the pressure of the lower oil pipe space, ρdowN is the density of the lower liquid, and hdowN is the height of the liquid in the lower oil pipe space.

3. A method for blocking an oilfield tubing according to claim 1, characterized in that, In the step S3, if the pressure Pdown of the lower oil pipe space is greater than the pressure Pup of the upper oil pipe space, a higher pressure is applied to the upper oil pipe space through the liquid injection control system until the predetermined pressure of the plug is reached, that is: Pup,new = Pdown + ΔP Where, ΔP is the differential compensation pressure.

4. A plugging method for an oilfield tubing according to claim 1, characterized in that, In the step S4, the isolation layer of the degradable plugging base is damaged by applying appropriate pressure to the upper oil pipe space, and the rupture pressure Pburst of the isolation layer is calculated by the following formula: Where, Pburst is the rupture pressure, Qflow is the oil and gas flow rate flowing through the plugging base, Aseal is the surface area of the isolation layer, and Δt is the time difference of the oil and gas flow rate flowing through the plugging base.

5. A method for blocking an oilfield tubing according to claim 1, characterized in that, It also includes controlling the injection amount of the liquid in the upper oil pipe space through real-time monitoring and pressure adjustment, and controlling the degradation rate of the isolation layer of the plugging base, where the degradation rate is controlled by the following model: Among them, is the degradation rate of the plugging base isolation layer, κ is the degradation constant, τ is the degradation time constant, and t is the time.

6. A plugging method for oilfield tubing according to claim 1, characterized in that, It also includes, after completing the plugging operation, pumping out the liquid in the upper oil pipe space through the liquid extraction system to reduce the pressure and remove the plug assembly, and this step is further controlled by the following formula: Premove = Pup - ΔPext Where, Premove is the pressure when removing the plug, and ΔPext is the external pressure adjustment amount.

7. A plugging method for oilfield tubing according to claim 1, characterized in that, The step S3 further includes: S31. If the pressure of the lower oil pipe is less than the pressure of the upper oil pipe, the system reduces the pressure of the upper oil pipe space through the liquid adjustment device to make it close to the pressure of the lower oil pipe space, so as to avoid damage to the plug caused by pressure imbalance; S32. Adjust the pressure balance inside the plug according to the pressure difference between the upper oil pipe space and the lower oil pipe space.

8. The multi-path fishing plugging device, according to a plugging method for an oilfield tubing as claimed in any one of claims 1 to 7, characterized in that, It includes an upper connector (1), the outer side of the upper connector (1) is threadedly connected to a lower connector (2), the inner side of the lower connector (2) is fixedly connected to a biodegradable plugging base (6), a plugging core shaft (3) is arranged on the inner side of the lower connector (2), a guiding head (4) is arranged at one end of the plugging core shaft (3), an adjusting head (5) is threadedly connected to the through hole on the outer surface of the plugging core shaft (3), a driving column (7) is fixedly connected to the inner side of the adjusting head (5), a fixing plate (12) is fixedly connected to the inside of the plugging core shaft (3), a connecting column (8) is slidably connected to the through hole inside the fixing plate (12), two connecting rods (11) are rotatably connected to one end of the connecting column (8), a clamping column (10) is rotatably connected to one end of the connecting rod (11), and two clamping grooves (9) are formed inside the guiding head (4).

9. The multi-path fishing plug according to claim 8, characterized in that, A spring is sleeved outside the clamping groove (9), one end of the spring is fixedly connected to the outside of the connecting column (8), and the other end of the spring is fixedly connected to the outside of the fixing plate (12).

10. The multi-path fishing plug according to claim 8, wherein, The cross-section of the clamping column (10) is square, the end of the clamping column (10) is inserted and matched with the inner side of the clamping groove (9), and inclined surfaces are arranged on one side of the connecting column (8) and the bottom of the driving column (7).

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