Tail pipe rubber plug, tail pipe rubber plug device with controllable breakdown pressure and application method of tail pipe rubber plug device

Abstract

The invention relates to the technical field of oil field drilling liner cementing, in particular to a drilling liner rubber plug, a drilling liner rubber plug device with controllable breakdown pressure and an application method of the drilling liner rubber plug device. The upper body and the lower body are used for bearing all parts of the tail pipe rubber plug and arranged on the upper portion and the lower portion of the tail pipe rubber plug respectively. The shear pin is used for connecting the tail pipe rubber plug and the central pipe, and when the pressure applied to the tail pipe rubber plug by the drill rod rubber plug reaches a first preset pressure value, the shear pin is cut off; the emergency shearing sleeve is fixed to the middle of the cavity of the lower body through the emergency pin, when the pressure applied to the tail pipe rubber plug by the drill rod rubber plug reaches a second preset pressure value, the emergency pin is cut off, and the emergency shearing sleeve continues to move downwards along with the drill rod rubber plug. When the tail pipe rubber plug body is blocked in the tail pipe and cannot be smoothly jacked through, an emergency breakdown mechanism can be started, and excessive cement paste is effectively prevented from being retained in the tail pipe.

Description

Technical Field

[0001] The invention relates to the technical field of oilfield liner cementing, in particular to a liner rubber plug, a controllable breakdown pressure liner rubber plug device and an application method thereof. Background Art

[0002] With the accelerated pace of oil and gas field exploration and development, the number of tail pipe operations has increased significantly. In the critical link of tail pipe cementing operations, operators often face a series of complex and special working conditions. For example, obstacles may be encountered during the lowering of the tail pipe, and it is necessary to use various means such as lifting, pressing down or rotating to try to pass through. These operations often cause changes in the internal diameter of the tail pipe, or due to quality problems of the tail pipe plug itself, it causes pressure to be blocked when the tail pipe encounters obstruction. This may not only cause a large amount of cement to remain in the tail pipe, but also affect the sealing quality of the annular cement, thereby posing a potential threat to the safety and production efficiency of the entire oil and gas well.

[0003] Traditional pressure-bearing tail pipe plugs are usually designed to withstand bursting pressures of up to 10,000 Psi, which is far beyond the pressure range required for normal cementing operations. Although this design improves the pressure-bearing capacity of the tail pipe plug to a certain extent, it also brings new problems in emergency situations. When it is necessary to urgently deal with abnormal conditions in the tail pipe, traditional tail pipe plugs are often unable to be penetrated due to excessive pressure, making it difficult to implement emergency measures. Summary of the invention

[0004] The object of the present invention is to provide a tail pipe rubber plug, a tail pipe rubber plug device with controllable breakdown pressure and an application method thereof in order to solve at least one of the above technical problems.

[0005] The present invention achieves the above-mentioned purpose through the following technical solutions:

[0006] A liner plug is used in conjunction with a drill pipe plug, the liner plug comprising: a shear pin, an upper body, a lower body, an emergency pin, and an emergency shear sleeve;

[0007] The upper body and the lower body are used to support the components of the tail pipe plug, and the upper body and the lower body are respectively arranged at the upper part and the lower part of the tail pipe plug;

[0008] The shear pin is used to connect the liner plug and the center pipe, and when the pressure applied by the drill pipe plug to the liner plug reaches a first preset pressure value, the shear pin is sheared off;

[0009] The emergency shear sleeve is fixed to the middle of the cavity of the lower body by the emergency pin. When the pressure applied by the drill pipe plug to the tail pipe plug reaches a second preset pressure value, the emergency pin is cut off and the emergency shear sleeve continues to descend with the drill pipe plug.

[0010] Furthermore, the first preset pressure value is 2000Psi.

[0011] Furthermore, the second preset pressure value is set according to 80% of the tail pipe's resistance to internal pressure.

[0012] Furthermore, the second preset pressure value is 6000Psi.

[0013] Furthermore, the number of the emergency pins matches the second preset pressure value.

[0014] Furthermore, the tail pipe rubber plug also includes: a leather cup, a backing ring, a first sealing ring, a bushing, a second sealing ring, a third sealing ring, a locking body, and a locking ring;

[0015] The inner wall of the upper body is connected to the lower body through the bushing; the outer wall of the bushing is provided with the leather cup, the bottom of the leather cup is provided with the support ring, the outer wall of the leather cup is provided with the first sealing ring, the second sealing ring is provided between the emergency shear sleeve and the inner wall of the lower body, the third sealing ring is provided at the outer wall of the lower body corresponding to the emergency shear sleeve, the locking body is provided at the bottom of the lower body, and the locking ring is provided on the outer wall of the locking body.

[0016] A controllable breakdown pressure tail pipe rubber plug device comprises: a tail pipe rubber plug and a drill pipe rubber plug as described above.

[0017] Furthermore, the drill pipe rubber plug comprises: a drill pipe leather cup, a sleeve, a sealing head, and a guide head;

[0018] The drill pipe leather cup is used for scraping the inner wall of the drill pipe, the two drill pipe leather cups are connected by the sleeve, and the drill pipe leather cup at the bottom is connected to the guide head through the sealing head.

[0019] An application method of a controllable breakdown pressure tail pipe rubber plug device, using any of the controllable breakdown pressure tail pipe rubber plug devices described above, the method comprising the following steps:

[0020] Perform surface preparation work, including wellbore circulation cleaning, drilling fluid performance adjustment, and tool inspection;

[0021] Arrange the tail pipe in place according to the preset pipe string and inject cement slurry;

[0022] Throwing the drill pipe rubber plug, and shearing the liner rubber plug by holding the pressure to a first preset pressure value, so that the drill pipe rubber plug and the liner rubber plug are integrated and continue to descend;

[0023] When the tail pipe rubber plug encounters resistance and causes pressure build-up, the emergency shear sleeve is sheared by building up pressure to a second preset pressure value, thereby establishing a flow channel to continue displacement and complete the cementing operation.

[0024] Furthermore, the first preset pressure value is 2000Psi;

[0025] and / or,

[0026] The second preset pressure value is 6000Psi.

[0027] The beneficial effects of the present invention are:

[0028] The present invention improves the traditional tail pipe plug by cleverly building in an emergency shear sleeve, which is set with a breakdown pressure of up to 6000Psi (or flexibly adjusted according to 80% of the tail pipe's internal pressure resistance, achieved by changing the number of shear pins), which significantly enhances the emergency handling capability of the tail pipe plug; when encountering emergency situations such as internal blockage of the tail pipe, the emergency shear sleeve can be easily sheared by simply increasing the pressure, prompting the drill pipe plug and the emergency shear sleeve to move downward in coordination and quickly construct a circulation channel. The present invention not only avoids the risk of emptying, but also ensures that the tail pipe cementing operation is successfully completed in an undisturbed process, greatly enhancing the operational safety and production efficiency of oil and gas wells. The present invention does not need to sacrifice the smoothness of the normal operating process, and demonstrates a high degree of practicality and technological advancement. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a schematic diagram of the tail pipe plug structure according to an embodiment of the present invention;

[0030] Figure 2 This is a schematic diagram of the structure of a drill pipe plug according to an embodiment of the present invention;

[0031] Figure 3 The present invention is a flowchart of an application method of a controllable breakdown pressure tail pipe rubber plug device according to an embodiment of the present invention.

[0032] Among them, 100, tail pipe plug, 101, shear pin, 102, upper body, 103, leather cup, 104, support ring, 105, first sealing ring, 106, lower body, 107, bushing, 108, second sealing ring, 109, third sealing ring, 110, emergency pin, 111, locking body, 112, locking ring, 113, emergency shear sleeve, 200, drill pipe plug, 201, drill pipe leather cup, 202, sleeve, 203, sealing head, 204, guide head. DETAILED DESCRIPTION

[0033] The content of the present invention will now be discussed with reference to exemplary embodiments. It should be understood that the embodiments discussed are only to enable those skilled in the art to better understand and thus implement the content of the present invention, rather than implying any limitation on the scope of the present invention.

[0034] As used herein, the term “including” and variations thereof are to be interpreted as open-ended terms meaning “including, but not limited to.” The term “based on” is to be interpreted as “based, at least in part, on.” The terms “one embodiment” and “an embodiment” are to be interpreted as “at least one embodiment.”

[0035] Embodiment 1

[0036] Figure 1 FIG. 1 is a schematic diagram of a tail pipe plug structure according to an embodiment of the present invention. Figure 1 As shown, according to an embodiment of the present invention, a liner plug is used in conjunction with a drill pipe plug 200, and the liner plug 100 includes: a shear pin 101, an upper body 102, a lower body 106, an emergency pin 110, and an emergency shear sleeve 113;

[0037] The upper body 102 and the lower body 106 are used to support the components of the tail pipe plug 100. The upper body 102 and the lower body 106 are respectively disposed at the upper part and the lower part of the tail pipe plug 100;

[0038] The shear pin 101 is used to connect the liner plug 100 and the center pipe. When the pressure applied by the drill pipe plug 200 to the liner plug 100 reaches a first preset pressure value, the shear pin 101 is sheared off;

[0039] The emergency shear sleeve 113 is fixed to the middle of the cavity of the lower body 106 by the emergency pin 110. When the pressure applied by the drill pipe plug 200 to the tail pipe plug 100 reaches a second preset pressure value, the emergency pin 110 is cut off, and the emergency shear sleeve 113 continues to descend with the drill pipe plug 200.

[0040] In this embodiment, a liner plug 100 is proposed, which is intended to work in conjunction with a drill pipe plug 200 to efficiently and safely complete key steps in drilling operations. The liner plug 100 includes a shear pin 101, an upper body 102, a lower body 106, an emergency pin 110, and an emergency shear sleeve 113. In terms of overall layout, the upper body 102 is located at the upper part of the liner plug 100, while the lower body 106 is located at the lower part. The two together carry all components of the liner plug 100, ensuring the stability of the structure and the integrity of the function.

[0041] As a key component connecting the liner plug 100 and the center pipe, the shear pin 101 plays a vital role. During normal operation, when the pressure applied by the drill pipe plug 200 to the liner plug 100 gradually increases until it reaches the preset first preset pressure value, the shear pin 101 will be sheared off as designed, thereby allowing the liner plug 100 to be separated from the center pipe for the next operation. This design not only improves the operating efficiency, but also ensures the safety of the operation.

[0042] In order to cope with possible abnormal situations, the present invention cleverly designs an emergency shear mechanism. The emergency shear sleeve 113 is fixed in the middle of the cavity of the lower body 106 through the emergency pin 110. If the pressure applied by the drill pipe plug 200 to the tail pipe plug 100 increases abnormally and reaches the preset second preset pressure value, the emergency pin 110 will be sheared off, and the emergency shear sleeve 113 will continue to move downward with the drill pipe plug 200, thereby triggering the emergency handling process and effectively avoiding possible accidents.

[0043] The liner plug 100 has extremely high flexibility, and its composite shear pressure (i.e., the first preset pressure value) and emergency shear pressure (i.e., the second preset pressure value) can be flexibly adjusted according to the actual situation at the drilling site. This feature enables the liner plug 100 to better adapt to different geological conditions and operational requirements, and improves the reliability and safety of drilling operations.

[0044] The present invention shows wide application potential in key engineering fields such as liner cementing. Its core technology is to realize an innovative process of controllable breakdown pressure. This feature can immediately activate the emergency breakdown mechanism when the liner plug body encounters an obstruction in the liner, resulting in the inability to push through the pressure. This mechanism can quickly establish a circulation flow channel and effectively avoid excessive cement slurry in the liner, thereby significantly reducing the time for drilling out the cement plug in the later stage and enhancing the sealing effect of the annular cement slurry. The present invention not only greatly improves the operating efficiency, but also significantly enhances the safety of the operation, providing a more reliable and efficient solution for construction in the fields of liner cementing.

[0045] According to one embodiment of the present invention, the first preset pressure value is 2000 Psi;

[0046] Preferably, the second preset pressure value is set to 80% of the tail pipe's resistance to internal pressure.

[0047] Preferably, the number of the emergency pins 110 matches the second preset pressure value.

[0048] In this embodiment, the design of the tail pipe plug 100 fully considers the pressure control and safety in the drilling operation. Specifically, the first preset pressure value is set to 2000Psi. This value ensures that the tail pipe plug 100 can maintain a stable connection state when the drill pipe plug 200 is applied with normal working pressure. At the same time, when the pressure reaches this threshold, the shear pin 101 will be accurately sheared off to separate the tail pipe plug 100 from the center pipe, pushing the operation process forward. Furthermore, in order to cope with abnormally high pressure conditions, the second preset pressure value is optimized to 80% of the tail pipe's internal pressure resistance. This design is based on the safe pressure bearing capacity of the tail pipe material, ensuring that even under extreme conditions, excessive pressure can be released in a safe manner. In this embodiment, the second preset pressure value is specifically set to 6000Psi, and the number of emergency pins 110 is matched thereto. These pins are evenly distributed and fix the emergency shear sleeve 113 in the middle of the cavity of the lower body 106, ensuring that when the second preset pressure value is reached, they can be collectively sheared, so that the emergency shear sleeve 113 can be safely lowered along with the drill pipe plug 200, and an emergency circulation channel is established, effectively preventing excessive retention of cement slurry in the tail pipe, reducing subsequent processing time and enhancing the cement slurry sealing effect. In addition, by adjusting the number of shear pins 101, the shear pressure can also be flexibly adjusted to adapt to different well conditions and operation requirements, reflecting the high flexibility and strong adaptability of the present invention.

[0049] The present invention ensures stable connection and timely separation during normal operation by accurately setting the first preset pressure value of 2000Psi. At the same time, the second preset pressure value is optimized to 80% of the tail pipe's internal pressure resistance (6000Psi in this case), and a corresponding number of emergency pins are matched to effectively deal with abnormally high pressure, establish an emergency circulation channel, prevent cement slurry retention, reduce subsequent processing time, enhance the sealing effect, show high flexibility and strong adaptability, and ensure the safety and efficiency of drilling operations.

[0050] According to an embodiment of the present invention, the tail pipe plug 100 further includes: a leather cup 103, a backing ring 104, a first sealing ring 105, a bushing 107, a second sealing ring 108, a third sealing ring 109, a locking body 111, and a locking ring 112;

[0051] The inner wall of the upper body 102 is connected to the lower body 106 through the bushing 107; a leather cup 103 is provided on the outer wall of the bushing 107, a supporting ring 104 is provided at the bottom of the leather cup 103, a first sealing ring 105 is provided on the outer wall of the leather cup 103, a second sealing ring 108 is provided between the emergency shear sleeve 113 and the inner wall of the lower body 106, a third sealing ring 109 is provided at the outer wall of the lower body 106 corresponding to the emergency shear sleeve 113, a locking body 111 is provided at the bottom of the lower body 106, and a locking ring 112 is provided on the outer wall of the locking body 111.

[0052] In this embodiment, the tail pipe plug 100 is composed of an upper body 102 and a lower body 106 as the main bearing components, and a bushing 107 is used to achieve a stable connection between the two. The upper body 102 is not only responsible for supporting the various key components of the tail pipe plug 100, but is also closely connected to the lower body 106 through the bushing 107 installed on its inner wall. On the outer wall of the bushing 107, a leather cup 103 is cleverly arranged, and the leather cup 103 can scrape the inner wall of the casing during the drilling process to ensure that it is smooth and free of impurities. In order to enhance the pressure-bearing capacity of the leather cup 103, a support ring 104 is particularly configured at its bottom. At the same time, a first sealing ring 105 is installed on the outer wall of the leather cup 103 to effectively prevent fluid leakage and ensure sealing performance.

[0053] In addition to being a bearing component, the lower body 106 further enhances the sealing performance of the liner plug 100 through the second sealing ring 108 disposed between its inner wall and the emergency shear sleeve 113, and the third sealing ring 109 disposed at the outer wall of the lower body 106 and the corresponding position of the emergency shear sleeve 113. This multiple sealing design can ensure that the sealing performance of the liner plug 100 is not affected even under extreme operating conditions.

[0054] In addition, the tail tube plug 100 is also equipped with a shear pin 101 for connecting the tail tube plug 100 with the center tube. During normal operation, when the pressure applied by the drill pipe plug 200 reaches the first preset pressure value, the shear pin 101 will be accurately sheared to separate the tail tube plug 100 from the center tube. In order to cope with possible abnormal situations, the present invention designs an emergency shear mechanism, that is, the emergency shear sleeve 113 is fixed to the middle of the cavity of the lower body 106 by the emergency pin 110. When the pressure increases abnormally and reaches the preset value, the emergency pin 110 will be sheared, and the emergency shear sleeve 113 will continue to descend with the drill pipe plug 200, triggering the emergency handling process.

[0055] A locking body 111 is provided at the bottom of the liner plug 100, and the locking mechanism is matched through a locking ring 112 on its outer wall. This design not only enhances the stability of the liner plug 100 during operation, but also provides a strong guarantee for its application under complex geological conditions.

[0056] The present invention integrates multiple functional components such as sealing, scraping, pressure bearing and emergency shearing to achieve efficient sealing, casing inner wall cleaning and safe emergency treatment under abnormal pressure in drilling operations, which significantly improves the stability and safety of operations.

[0057] Embodiment 2

[0058] Figure 2 FIG. 1 is a schematic diagram of a drill pipe plug structure according to an embodiment of the present invention. Figure 2As shown, according to an embodiment of the present invention, a controllable breakdown pressure liner plug device includes: any liner plug 100 of the present invention and a drill pipe plug 200.

[0059] Preferably, the drill pipe rubber plug 200 comprises: a drill pipe leather cup 201, a sleeve 202, a sealing head 203, and a guide head 204;

[0060] The drill pipe leather cup 201 is used to scrape the inner wall of the drill pipe. The two drill pipe leather cups 201 are connected by a sleeve 202, and the drill pipe leather cup 201 at the bottom is connected to the guide head 204 through a sealing head 203.

[0061] In the present embodiment, a controllable breakdown pressure tail pipe plug device is proposed, which integrates the tail pipe plug 100 and the drill pipe plug 200 design proposed in the present invention. The specific structure of the tail pipe plug 100 refers to the detailed description of Example 1. As the core part of the device, the tail pipe plug 100 has key functions such as multiple sealing, pressure bearing and emergency shearing to ensure the safety and efficiency of drilling operations. The drill pipe plug 200, as a key component that cooperates with the tail pipe plug 100, has a sophisticated structure and comprehensive functions. The drill pipe plug 200 consists of a drill pipe leather cup 201, a sleeve 202, a sealing head 203 and a guide head 204. Among them, the drill pipe leather cup 201 is responsible for scraping the inner wall of the drill pipe to ensure that it is smooth and free of impurities. The two leather cups are connected and fixed by a sturdy sleeve 202 to ensure the stability of the structure. The drill pipe leather cup 201 at the bottom is tightly connected to the guide head 204 through the sealing head 203. The sealing head 203 is designed to form a tight seal with the inside of the liner plug 100 to prevent fluid leakage, while the guide head 204 plays a key role in guiding the drill pipe plug 200 to smoothly descend and accurately insert the liner plug 100. During the operation, as the drill pipe plug 200 descends, it will pass through each sealing area of ​​the liner plug 100 in turn. When the pressure reaches the first preset pressure value, the shear pin 101 of the liner plug 100 will be accurately sheared to achieve separation from the center pipe. At the same time, the drill pipe plug 200 continues to descend, pushing the emergency shear mechanism inside the liner plug 100 to start, ensuring that emergency treatment can be carried out safely under abnormal circumstances.

[0062] The controllable breakdown pressure tail pipe plug device proposed in the present invention realizes multiple functions such as efficient sealing, cleaning the inner wall of the drill pipe and safe emergency treatment in drilling operations through the precise coordination and ingenious design of the tail pipe plug and the drill pipe plug, which significantly improves the stability and safety of the operation.

[0063] Embodiment 3

[0064] According to an embodiment of the present invention, a controllable breakdown pressure liner plug cementing device includes a liner plug 100 (such as Figure 1 As shown) and drill pipe plug 200 (as shown Figure 2 shown);

[0065] The tail pipe plug 100 includes: a shear pin 101, an upper body 102, a leather cup 103, a backing ring 104, a first sealing ring 105, a lower body 106, a bushing 107, a second sealing ring 108, a third sealing ring 109, an emergency pin 110, a locking body 111, a locking ring 112, and an emergency shear sleeve 113;

[0066] The shear pin 101 is used to connect the tail pipe plug 100 and the center pipe, the upper body 102 is used to support various components, the leather cup 103 is used to clean the inner wall of the casing, the support ring 104 is used to support the leather cup to bear pressure, the first sealing ring 105 is used for sealing, the lower body 106 is used to support various components, the bushing 107 is used for leather cup connection, the second sealing ring 108 is used for sealing, the third sealing ring 109 is used for sealing, the emergency pin 110 is used for emergency shearing, the locking body 111 is used for cooperative locking, the locking ring 112 is used for locking mechanism, and the emergency shear sleeve 113 is used for emergency shearing with the drill pipe plug.

[0067] The drill pipe rubber plug 200 includes: a drill pipe leather cup 201, a sleeve 202, a sealing head 203, and a guide head 204;

[0068] The drill pipe leather cup 201 is used to scrape the inner wall of the drill pipe, the sleeve 202 is used to connect and fix the leather cup, the sealing head 203 is used to seal with the inside of the liner plug, and the guide head 204 is used to guide the downward insertion of the liner plug 100.

[0069] In this embodiment, during the liner cementing operation, after the cement slurry is injected, the drill pipe plug 200 is released, and the drill pipe plug 200 is displaced and moved downward to the position of the emergency shear sleeve 113 of the liner plug 100. After the pressure rises, the pressure is further increased to 2000Psi, and the shear pin 101 is cut off. The drill pipe plug 200 and the liner plug 100 are combined into one body and continue to move downward to clean the casing. If the liner plug 100 body cannot move downward due to resistance in the casing and other reasons, resulting in a pressure-blocking situation, the emergency pin 110 can be sheared by pressing to 6000Psi (the shear pressure can be adjusted by the number of shear pins 101, generally set according to 80% of the internal pressure resistance of the liner), and the emergency shear sleeve 113 and the drill pipe plug 200 move downward to establish a circulation channel, and continue to displace to the designed safety margin, stop displacing, and complete the cementing operation, so as to avoid a large amount of cement remaining in the liner and poor quality of cement sealing in the annulus.

[0070] The controllable breakdown pressure tail pipe plug device of the present invention solves the problem that the traditional tail pipe plug cannot establish a circulation channel due to the pressure build-up after encountering an obstruction by adding an emergency shear sleeve, thereby improving the safety of the operation. The present invention has a simple structure, low cost, and convenient operation, and has good application prospects and the advantage of saving post-processing costs, and can be widely used in the fields of tail pipe cementing.

[0071] Embodiment 4

[0072] Figure 3 This is a flow chart of the application method of the controllable breakdown pressure tail pipe rubber plug device according to one embodiment of the present invention. Figure 3 As shown, according to an embodiment of the present invention, an application method of a controllable breakdown pressure tail pipe rubber plug device adopts any controllable breakdown pressure tail pipe rubber plug device of the present invention, and the method comprises the following steps:

[0073] Step S102, performing ground preparation work, including wellbore circulation cleaning, drilling fluid performance adjustment, and tool inspection;

[0074] Step S104, placing the tail pipe in place according to the preset pipe string arrangement and performing cement slurry injection;

[0075] Step S106, delivering the drill pipe rubber plug 200, and shearing the liner rubber plug 100 by holding the pressure to a first preset pressure value, so that the drill pipe rubber plug 200 and the liner rubber plug 100 are combined into one and continue to descend;

[0076] Step S108, when the liner plug 100 encounters resistance and causes pressure build-up, the emergency shear sleeve 113 is sheared by building up pressure to a second preset pressure value, thereby establishing a flow channel to continue displacement and complete the cementing operation.

[0077] Preferably, the first preset pressure value is 2000Psi;

[0078] and / or,

[0079] The second preset pressure value is 6000Psi.

[0080] In this embodiment, an application method of a controllable breakdown pressure tail pipe plug device is proposed. The method adopts an innovative design of tail pipe plug 100 and drill pipe plug 200, and realizes efficient and safe tail pipe cementing operation through a series of precisely controlled steps. First, sufficient preparation work is carried out on the ground, including wellbore circulation cleaning, drilling fluid performance adjustment and tool inspection to ensure the cleanliness of the working environment and the normal operation of the tool. Subsequently, the tail pipe is arranged in place according to the preset pipe string, and cement slurry is injected. For example, the recommended pipe string arrangement is: floating shoe + single tail pipe + floating hoop + single tail pipe + impact pressure hoop + tail pipe string + tail pipe hanger + delivery drill pipe + cement head. Next, the drill pipe plug 200 is delivered, and the tail pipe plug 100 is accurately sheared by holding the pressure to the first preset pressure value (such as 2000Psi), so that the drill pipe plug 200 and the tail pipe plug 100 are combined into one and continue to go down to clean the inner wall of the casing. During the operation, if the liner plug 100 cannot move downward due to resistance in the casing and other reasons, resulting in a pressure-blocking situation, the emergency shear sleeve 113 can be sheared by continuing to pressurize to a second preset pressure value (such as 6000Psi, which can be set by adjusting the number of shear pins according to the principle of 80% resistance of the liner internal pressure) to make the emergency shear sleeve 113 and the drill pipe plug 200 move downward, establish a circulation flow channel, continue to displace to the designed safety margin, and complete the cementing operation. This method not only avoids a large amount of cement remaining in the liner, but also ensures the quality of annular cement sealing, significantly improving the safety and efficiency of the liner cementing operation.

[0081] The present invention significantly improves the traditional difficulties of liner cementing operations, especially when the liner plug encounters resistance. By introducing an emergency shear mechanism, when the liner plug encounters hard resistance in the casing and cannot continue to move downward, a circulation channel can be quickly established, effectively avoiding the risk of a large amount of cement slurry being retained in the liner, thereby ensuring the quality of annular cement sealing. The present invention not only greatly improves the safety of operations and reduces potential risks, but also has a simple and reasonable structure, high reliability, and reduces the complexity and cost of post-processing. The present invention achieves high efficiency and safety in liner cementing operations through precisely controlled steps and innovative component design, bringing significant technological progress to the field of oil drilling.

[0082] Embodiment 5

[0083] According to one embodiment of the present invention, an application method of a controllable breakdown pressure liner plug cementing device comprises the following steps:

[0084] Step S201, ground preparation work; specifically including:

[0085] ①Sufficient circulation to ensure the wellbore is unobstructed and clean.

[0086] ② Adjust the properties of the drilling fluid to make it suitable for cementing requirements and ensure the safety and stability of the well wall.

[0087] ③ Check whether the tools are complete, whether the accessories are matched, and whether the rubber plugs are intact.

[0088] Step S202, the recommended arrangement of the pipe string is: float shoe + single liner + float collar + single liner + impact joint collar + liner string + liner hanger + delivery drill pipe + cement head.

[0089] Step S203: put the tail pipe in place and perform cement slurry injection.

[0090] Step S204, throwing the drill pipe plug 200, using drilling fluid or seawater to replace, pumping the drill pipe plug 200 to the liner plug 100, holding the pressure at 2000Psi to shear the liner plug 100, and the drill pipe plug 200 and the liner plug 100 are combined into one and continue to descend.

[0091] Step S205, in normal construction, the displacement is continued until the pressure collar is hit to complete the operation. In case of abnormal situation, the tail pipe rubber plug 100 is grouped and the pressure is blocked, and the displacement cannot be continued. The cementing pump can be used to pressurize 6000Psi (the shear pressure can be adjusted by the number of emergency pins 110, generally set according to 80% of the tail pipe internal pressure resistance) to shear the emergency shear sleeve 113, establish the flow channel, continue to displace, and complete the cementing operation.

[0092] In this embodiment, a method for applying a controllable breakdown pressure liner plug cementing device is first performed on the ground, including wellbore circulation cleaning, drilling fluid performance adjustment, and tool inspection, etc., and then the liner is arranged in place according to the recommended pipe string and cement slurry is injected. After delivering the drill pipe plug 200, the liner plug 100 is sheared by holding the pressure at 2000Psi, so that the two can be combined and continue to move downward. If the liner plug 100 encounters resistance and causes pressure holding, a cementing pump can be used to pressurize 6000Psi (the shear pressure can be adjusted according to the number of emergency pins 110) to shear the emergency shear sleeve 113, establish a flow channel to continue displacement, and complete the cementing operation.

[0093] The present invention can be widely used in the fields of liner cementing, etc. The unique controllable breakdown pressure process can perform emergency breakdown when the liner plug body encounters resistance in the liner and cannot be pushed through due to pressure buildup, thereby establishing a circulation flow channel and avoiding leaving too much cement slurry in the liner, thereby reducing the time for drilling cement plugs in the later stage and enhancing the sealing effect of annular cement slurry, greatly improving the safety of the operation.

[0094] The tail pipe plug of the present invention is exquisitely designed and has multiple advantages such as compact structure, small size, light weight, easy processing, low cost and simple on-site operation. On the basis of ensuring the reliability of the original tail pipe plug, the present invention incorporates an innovative emergency shear mechanism, which significantly improves the safety of the operation. Through the local optimization and modification of the existing tail pipe plug, the present invention can be easily adapted and shows broad application potential, especially suitable for special operations such as tail pipe cementing. The present invention effectively solves the problem that the traditional pressure-bearing tail pipe plug is prone to pressure build-up and difficulty in establishing a circulation channel after being blocked in the tail pipe. The design is simple and reasonable, ensuring a high degree of reliability and greatly reducing the subsequent processing costs.

[0095] The above description is only a preferred embodiment of the present application and an explanation of the technical principles used. Those skilled in the art should understand that the scope of the invention involved in the present application is not limited to the technical solution formed by a specific combination of the above technical features, but should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the inventive concept. For example, the above features are replaced with (but not limited to) technical features with similar functions disclosed in the present application.

[0096] It should be understood that the size of the serial numbers of each step in the content of the invention and the embodiments of the present invention does not absolutely mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

Claims

1. A liner rubber plug, used in conjunction with a drill pipe rubber plug (200), characterized in that: The tail pipe rubber plug (100) comprises: a shear pin (101), an upper body (102), a lower body (106), an emergency pin (110), and an emergency shear sleeve (113); The upper body (102) and the lower body (106) are used to support various components of the tail pipe rubber plug (100), and the upper body (102) and the lower body (106) are respectively arranged at the upper part and the lower part of the tail pipe rubber plug (100); The shear pin (101) is used to connect the liner plug (100) and the center pipe, and when the pressure applied by the drill pipe plug (200) to the liner plug (100) reaches a first preset pressure value, the shear pin (101) is sheared off; The emergency shear sleeve (113) is fixed to the middle of the cavity of the lower body (106) through the emergency pin (110); when the pressure applied by the drill pipe plug (200) to the tail pipe plug (100) reaches a second preset pressure value, the emergency pin (110) is cut off, and the emergency shear sleeve (113) continues to move downward along with the drill pipe plug (200).

2. The tail pipe plug according to claim 1, characterized in that: The first preset pressure value is 2000Psi.

3. The tail pipe rubber plug according to claim 1, characterized in that: The second preset pressure value is set according to 80% of the tail pipe's resistance to internal pressure.

4. The tail pipe rubber plug according to claim 3, characterized in that: The second preset pressure value is 6000Psi.

5. The tail pipe rubber plug according to claim 1, characterized in that: The number of the emergency pins (110) matches the second preset pressure value.

6. The tail pipe rubber plug according to claim 1, characterized in that: The tail pipe rubber plug (100) further comprises: a leather cup (103), a backing ring (104), a first sealing ring (105), a bushing (107), a second sealing ring (108), a third sealing ring (109), a locking body (111), and a locking ring (112); The inner wall of the upper body (102) is connected to the lower body (106) through the bushing (107); the outer wall of the bushing (107) is provided with the leather cup (103), the bottom of the leather cup (103) is provided with the supporting ring (104), the outer wall of the leather cup (103) is provided with the first sealing ring (105), the second sealing ring (108) is provided between the emergency shear sleeve (113) and the inner wall of the lower body (106), the third sealing ring (109) is provided at the outer wall of the lower body (106) corresponding to the emergency shear sleeve (113), the bottom of the lower body (106) is provided with the locking body (111), and the outer wall of the locking body (111) is provided with the locking ring (112).

7. A controllable breakdown pressure tail pipe plug device, characterized in that: include: A liner plug (100) and a drill pipe plug (200) as claimed in any one of claims 1 to 6.

8. The controllable breakdown pressure tail pipe rubber plug device according to claim 7, characterized in that: The drill pipe rubber plug (200) comprises: a drill pipe leather cup (201), a sleeve (202), a sealing head (203), and a guide head (204); The drill pipe leather cup (201) is used for scraping the inner wall of the drill pipe, and the two drill pipe leather cups (201) are connected via the sleeve (202), and the drill pipe leather cup (201) at the bottom is connected to the guide head (204) via the sealing head (203).

9. An application method of a controllable breakdown pressure tail pipe rubber plug device, using the controllable breakdown pressure tail pipe rubber plug device as claimed in any one of claims 7 to 8, characterized in that: The method comprises the following steps: Perform surface preparation work, including wellbore circulation cleaning, drilling fluid performance adjustment, and tool inspection; Arrange the tail pipe in place according to the preset pipe string and inject cement slurry; Throwing the drill pipe rubber plug (200), and shearing the liner rubber plug (100) by holding the pressure to a first preset pressure value, so that the drill pipe rubber plug (200) and the liner rubber plug (100) are combined into one and continue to descend; When the tail pipe rubber plug (100) encounters resistance and causes pressure build-up, the emergency shear sleeve (113) is sheared by building up pressure to a second preset pressure value, thereby establishing a flow channel to continue displacement and complete the cementing operation.

10. The application method of the controllable breakdown pressure tail pipe rubber plug device according to claim 9, characterized in that: The first preset pressure value is 2000Psi; and / or, The second preset pressure value is 6000Psi.

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