Pressure buffer device for cementing plugs

Abstract

The application belongs to the field of oil and gas exploration and development, and particularly relates to a pressure buffering device for a cementing rubber plug. The device comprises a body, a protection cylinder and a moving part. The body is configured as a hollow cylindrical structure, and a first flow hole and a connecting section configured to be connected with the rubber plug are arranged on the body. The protection cylinder is sleeved on the outside of the body, and a third flow hole is arranged on the protection cylinder. The moving part is arranged between the body and the protection cylinder, and comprises a piston and a spring arranged below the piston, and a second flow hole is arranged on the piston. The piston is configured to compress the spring and move upward in response to abnormal cementing pressure, so that the first flow hole, the second flow hole and the third flow hole are connected to perform pressure relief operation. The device can greatly reduce the damage of the rubber plug caused by excessive pressure fluctuation in the cementing process, and has good application prospect in the field.

Description

Technical Field

[0001] This invention belongs to the field of oil and gas exploration and development, and specifically relates to a pressure buffer device for cementing plugs. Background Technology

[0002] With the development of oil exploration technology, well depths are increasing and well temperatures are rising, leading to a gradual increase in pressure during cementing operations. Rubber plugs, as a crucial tool for mud replacement during cementing, play an indispensable role in the process. As cementing pressure continues to rise, fluctuations in the tubing pressure can easily damage the rubber plug system, affecting cementing quality and consequently, oil and gas production. Currently, conventional rubber plug systems connect the plug to other cementing tools via threads and are sealed with a rubber cup, lacking any pressure buffering mechanism, making them relatively weak in responding to pressure fluctuations within the tubing. Summary of the Invention

[0003] To address the problem that existing cementing plugs are easily damaged during cementing processes due to pressure fluctuations within the tubing, this invention provides a pressure buffer device for cementing plugs.

[0004] The pressure buffer device for cementing plugs includes:

[0005] The body is constructed as a hollow cylindrical structure, and a first vent hole and a connecting section that can be connected to a rubber stopper are provided on the body.

[0006] The protective sleeve, constructed as a hollow cylindrical structure, is fitted onto the outside of the main body and includes a third vent hole formed on the protective sleeve; and

[0007] The actuating part, disposed between the main body and the protective cylinder, includes a piston and a spring disposed above the piston, and a second vent hole is provided on the piston.

[0008] The piston is configured to compress the spring and move upward in response to abnormal cementing pressure, thereby connecting the first vent hole, the second vent hole, and the third vent hole to perform pressure relief operations.

[0009] As an extension of the above technical solution, the present invention also provides the following embodiments:

[0010] The main body includes a working section, a carrying section, and a tail section that are connected in sequence from bottom to top and whose outer diameters increase sequentially. The protective cylinder abuts against the lower end face of the tail section. The actuating part is disposed inside the actuating chamber between the protective cylinder and the working section. The spring is connected to the lower end face of the carrying section.

[0011] An auxiliary hole is provided on the main body, which penetrates the side wall of the main body and connects the central cavity of the main body with the action chamber.

[0012] The connecting segment is disposed below the working segment, and the connecting segment is configured to have an outer diameter smaller than that of the working segment.

[0013] An annular groove is formed on the inner wall of the protective cylinder, and the third drain hole is configured to communicate with the annular groove.

[0014] The sum of the flow areas of all the third drain holes, the sum of the flow areas of all the first drain holes, and the sum of the flow areas of all the second drain holes are all configured to be no less than the flow area of ​​the body.

[0015] It includes a sealing assembly disposed between the piston and the body, between the piston and the protective cylinder, and between the protective cylinder and the body.

[0016] The sealing assembly includes a shaped ring assembly and a first sealing ring disposed between the body and the piston and respectively located below and above the first vent hole. The shaped ring assembly includes a shaped ring and two retaining rings located on the upper and lower sides of the shaped ring.

[0017] The irregular ring assembly is configured such that it remains within the sealing stroke of the irregular ring assembly when the pressure relief operation is performed in the second vent hole.

[0018] The piston is constructed with a surface microtextured treatment.

[0019] The advantages of this invention compared to the prior art are:

[0020] By combining the main body, protective sleeve, and actuating unit, an automatic pressure relief function is achieved when the pressure fluctuation inside the tubing is too large. This greatly reduces the probability of rubber plug damage due to excessive pressure fluctuation inside the tubing during cementing operations, ensuring the smooth progress of cementing operations, improving the efficiency of cementing operations, and reducing cementing costs. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the pressure buffer device for cementing plugs according to the present invention in the non-depressurization state;

[0022] Figure 2 This is a schematic diagram of the structure when the pressure buffer device used for cementing rubber plugs is connected to the rubber plugs;

[0023] Figure 3 This is a schematic diagram of the protective cylinder.

[0024] Figure 4This is a schematic diagram of the irregular ring structure;

[0025] Figure 5 This is a schematic diagram of the retaining ring.

[0026] All the accompanying drawings in this invention are schematic diagrams for illustrating the structure and principle, and are not necessarily drawn according to actual dimensions and proportions.

[0027] The specific meanings of the various labels in the figure are as follows:

[0028] 1. Body; 11. First drain hole; 12. Connecting section; 121. Thread; 122. First sealing groove; 13. Working section; 14. Bearing section; 141. Blind hole; 15. Tail section; 16. Central cavity; 17. Auxiliary hole; 18. Second connecting hole; 2. Actuating part; 21. Piston; 211. Second drain hole; 22. Spring; 23. Actuating chamber; 3. Protective cylinder; 31. Third drain hole; 32. Annular groove; 33. First connecting hole; 4. Sealing assembly; 41. Shaped ring assembly; 411. Shaped ring; 412. Retaining ring; 42. First sealing ring; 43. Second sealing ring; 44. Third sealing ring; 5. Pin; 100. Pressure buffer device for cementing rubber plugs; 200. Rubber plug. Detailed Implementation

[0029] The present invention will now be described in more detail with reference to the accompanying drawings.

[0030] Figure 1 This is a schematic diagram of the pressure buffer device 100 for cementing plugs according to the present invention (hereinafter referred to as device 100) in the non-depressurization state. Figure 2 This is a schematic diagram of the structure when the device 100 is connected to the rubber stopper 200. As shown, the device 100 includes a body 1, a protective cylinder 3, and an actuating part 2. The body 1 is a hollow, bottomless cylindrical structure with a first vent hole 11 and a connecting section 12 configured to connect with the rubber stopper 200. The protective cylinder 3 is also a hollow, bottomless cylindrical structure, fitted onto the outside of the body 1, and has a third vent hole 31. The position of the third vent hole 31 corresponds to the position of the first vent hole 11. The actuating part 2 is located between the body 1 and the protective cylinder 3, and includes a piston 21 and a spring 22 positioned above the piston 21. A second vent hole 211 is located on the piston 21, and the distribution of the second vent hole 211 around the piston 21 corresponds to the distribution of the first vent hole 11 around the body 1. The piston 21 is also configured to compress the spring 22 and move upward in response to abnormal cementing pressure (referring to excessive cementing operation pressure), so that the first vent hole 11, the second vent hole 211 and the third vent hole 31 are connected to perform pressure relief operation.

[0031] like Figure 2 As shown, during actual operation, the operator connects the rubber plug 200 to the device 100 via an intermediate component, lowers the device 100 to the appropriate position in the tubing string (not shown), and begins injecting cement slurry into the tubing string through the pipe connected to the device 100 at the wellhead. The cement slurry moves downward through the central cavity 16 of the body 1 and the hollow rubber plug 200. When the cement slurry density is too high and its flow is obstructed, pressure buildup occurs below the device 100 and the rubber plug 200. This causes an abnormal increase in cementing pressure within the tubing, resulting in significant fluctuations. Due to the pressure buildup below the device 100 and the rubber plug 200, with continuous cement slurry injection, mud and other fluids within the tubing flow upwards through the rubber plug 200. Because the rubber plug 200 provides a one-way seal, the fluid can only rise through it, eventually expanding the pressure buildup area to the device 100. Since there is a relatively narrow area above the rubber plug 200, this pressure buildup acts simultaneously on both the rubber plug 200 and the piston 22, applying a downward thrust to the rubber plug 200 and an upward thrust to the piston 21. When the thrust applied to the piston 21 reaches a certain level, it triggers the piston 21 to compress the spring 22, causing it to move upwards. Before the piston 21 moves upwards, the first drain hole 11, the second drain hole 211, and the third drain hole 31 are not connected. After the piston 21 moves to its upper position, the first vent 11, the second vent 211, and the third vent 31 are connected. Cement slurry and other fluids inside the central cavity 16 of the body 1 flow into the annulus between the device 100 and the tubing through the channel formed by the first vent 11, the second vent 211, and the third vent 31. This provides pressure relief, buffers pressure fluctuations, and prevents premature release of the rubber plug 200 when the accumulated pressure reaches its release pressure, thus ensuring the normal progress of cementing operations.

[0032] According to the device 100 of the present invention, by combining the device 1, the protective cylinder 3 and the actuating part 2, an automatic pressure relief function is realized when the pressure fluctuation in the tubing is too large due to an abnormal increase. This greatly reduces the probability of premature release and damage of the rubber plug 200 due to excessive pressure fluctuation in the tubing during cementing operations, ensuring the smooth progress of cementing operations, improving the efficiency of cementing operations, and reducing cementing costs.

[0033] In some embodiments of the present invention, the body 1, the protective cylinder 3, and the piston 21 maintain optimal coaxiality during the manufacturing process to ensure that the piston 21 can be reset under the action of the spring 22 after the pressure relief operation.

[0034] In some embodiments of the present invention, the spring 22 is a high-strength spring, whose elastic force is required to prevent leakage under normal cementing pressure, and to contract under the action of the piston 21 after exceeding the normal cementing circulation pressure to complete the leakage action. It should be noted that the normal cementing pressure is less than the pressure that causes the rubber plug 200 to release, and there is a large pressure range between the normal cementing pressure and the pressure that causes the rubber plug 200 to release.

[0035] like Figure 1 As shown, in some embodiments of the present invention, the body 1 includes a working section 13, a carrying section 14, and a tail end 15, which are connected sequentially from bottom to top and have progressively increasing outer diameters. A protective cylinder 3 abuts against the lower end face of the tail end 15. An actuation chamber 23 is formed between the protective cylinder 3 and the working section 13, and an actuating part 2 is disposed within the actuation chamber 23. A spring 22 is connected to the lower end face of the carrying section 14. This design helps to improve the structural stability of the device 100.

[0036] like Figure 1 As shown, in some embodiments of the present invention, an auxiliary hole 17 is provided on the main body 1. The auxiliary hole 17 is constructed to penetrate the side wall of the main body 1, thereby connecting the central cavity 16 of the main body 1 with the actuation chamber 23. With this design, during the movement of the spring 22 and the piston 21, the liquid or gas inside the actuation chamber 23 can flow into the central cavity 16 through the auxiliary hole 17, thereby avoiding the situation where the piston 21 cannot move smoothly due to air pressure or hydraulic pressure because the actuation chamber 23 is in a completely sealed state, thus ensuring the smooth realization of the function of the device 100.

[0037] like Figure 1 As shown, in some embodiments of the present invention, the connecting segment 12 is connected and disposed below the working segment 13, and the connecting segment 12 is configured to have an outer diameter smaller than that of the connecting segment 13.

[0038] Preferably, in some embodiments of the present invention, a thread 121 for connecting to the rubber plug 200 is provided on the outer side of the connecting section 12.

[0039] Preferably, in some embodiments of the present invention, a first sealing groove 122 is provided on the outer side of the connecting section 12, above and / or below the thread 121. Workers can achieve a sealing function by installing a seal in the first sealing groove 122.

[0040] like Figure 1 and Figure 3As shown, in some embodiments of the present invention, an annular groove 32 is provided on the inner wall of the protective cylinder 3, and all the third drain holes 31 are constructed to communicate with the annular groove 32. Through the arrangement of the annular groove 32 and the structural design of the third drain holes 31 communicating with the annular groove 32, liquid flowing through the first drain hole 11 and the second drain hole 211 can flow out along the annular groove 32 and out through the third drain hole 31, as long as it can flow into the annular groove 32. This reduces the degree of correspondence between the shapes of the first drain hole 11 and the second drain hole 211 and the shapes and positions of the first drain hole 11, the second drain hole 211 and the third drain hole 31, while also achieving complete conductivity between the first drain hole 11, the second drain hole 211 and the third drain hole 31.

[0041] Furthermore, in some embodiments of the present invention, the sum of the flow areas of all third vent holes 31, the sum of the flow areas of all first vent holes 11, and the sum of the flow areas of all second vent holes 211 are all configured to be no less than the flow area of ​​the body 1. This design allows the liquid flowing into the body 1 to quickly and completely pass through the first vent holes 11, the second vent holes 211, and the third vent holes 31 into the annulus between the tubing and the device 100 when there is pressure buildup in the tubing string. This achieves the function of quickly relieving pressure buildup and ensures the smooth progress of cementing operations.

[0042] Preferably, in some embodiments of the present invention, the sum of the flow areas of all the third drain holes 31, the sum of the flow areas of all the first drain holes 11, and the sum of the flow areas of all the second drain holes 211 are all configured to be equal to the flow area of ​​the body 1.

[0043] like Figure 1 As shown, in some embodiments of the present invention, the device 100 includes a sealing assembly 4 disposed between the piston 21 and the body 1, between the piston 21 and the protective cylinder 3, and between the protective cylinder 3 and the body 1. Through the design of the sealing assembly 4, partial sealing of the actuation chamber 23 is achieved, thereby allowing hydraulic pressure outside the actuation chamber 23 to smoothly drive the piston 21 to move, thus ensuring the smooth operation of the device 100.

[0044] like Figure 1 , Figure 4 and Figure 5As shown, in some embodiments of the present invention, the sealing assembly 4 includes a shaped ring assembly 41 and a first sealing ring 42 disposed between the body 1 and the piston 21 and respectively located below and above the first drain hole 11. The shaped ring assembly 41 includes a shaped ring 41 and two retaining rings 412 located on the upper and lower sides of the shaped ring 411. The shaped ring 41 is constructed with a transverse cross section of an "Ω" shape. Combined with the two retaining rings 412, it forms a relatively flat sealing surface on the side facing the piston 21. The combination of the shaped ring 41 and the two retaining rings 412 forms a robust sealing structure, which can greatly reduce the probability of the shaped ring assembly 41 falling off or being damaged due to the sliding of the piston 21 and the scraping of the second drain hole 211, thus ensuring the smooth progress of subsequent cementing operations.

[0045] Furthermore, in some embodiments of the present invention, in order to achieve a better sealing effect, the profiled ring assembly 41 is configured such that it remains within the sealing stroke of the profiled ring assembly 41 when the second vent hole 211 is depressurized. This embodiment can be achieved by adjusting the maximum distance between the profiled ring assembly 41 and the first vent hole 11 to be less than the length of the portion of the piston 21 located below the second vent hole 211.

[0046] In some embodiments of the present invention, the retaining ring 412 is selected as an "L"-shaped retaining ring with an "L"-shaped cross section or a "T"-shaped retaining ring with a "T"-shaped cross section.

[0047] like Figure 1 As shown, in some embodiments of the present invention, a second sealing ring 43 is provided between the piston 21 and the protective cylinder 3, and a third sealing ring 44 is provided between the protective cylinder 3 and the body 1.

[0048] It is evident that corresponding sealing grooves are provided on the body 1, piston 21, and protective cylinder 3 at positions corresponding to the irregular ring assembly 41, the first sealing ring 42, the second sealing ring 43, and the third sealing ring 44.

[0049] In some embodiments of the present invention, the first sealing ring 42, the second sealing ring 43 and the third sealing ring 44 are all selected as "O" rings with an "O" shaped cross section.

[0050] In some embodiments of the present invention, the piston 21 is constructed with a microtextured surface, that is, several fine lines are formed on the surface of the piston 21. This treatment enables the piston 21 to maintain good lubrication during reciprocating motion.

[0051] In some embodiments of the present invention, the piston 21 is made of aluminum bronze.

[0052] In some embodiments of the present invention, in order to enable the device 100 to be used for a long time in the downhole environment, the body 1, the protective cylinder 3 and the actuating part 2 are all constructed to be rust-proof and corrosion-proof.

[0053] like Figure 1 As shown, in some embodiments of the present invention, a first connecting hole 33 is provided in the protective cylinder 3 at a position corresponding to the bearing section 14, and a blind hole 141 is provided on the bearing section 14 at a position corresponding to the first connecting hole 33. A fixed connection between the protective cylinder 3 and the body 1 is achieved by inserting a pin 5 into the first connecting hole 33 and the blind hole 141.

[0054] like Figure 1 As shown, in some embodiments of the present invention, a second connection hole 18 is provided on the tail section 15 for connecting the device 100 to other downhole tools.

[0055] According to the device 100 of the present invention, by combining the device 1, the protective cylinder 3 and the actuating part 2, an automatic pressure relief function is realized when the pressure fluctuation inside the tubing is too large due to an abnormal increase. This greatly reduces the probability of damage to the rubber plug 200 due to excessive pressure fluctuation inside the tubing during cementing operations, ensuring the smooth progress of cementing operations, improving the efficiency of cementing operations, and reducing cementing costs.

[0056] In this invention, "connection" includes "direct connection" and "indirect connection".

[0057] In this invention, the specific meanings of terms such as "upper," "lower," "left," "right," "inner," "outer," "middle," and "side" when indicating location are as follows: Figure 1 The drawing state of the middle device 100 is for reference.

[0058] Finally, it should be noted that although the present invention has been described in detail with reference to preferred embodiments, various modifications can be made and components can be replaced with equivalents without departing from the scope of the invention. In particular, as long as there is no structural conflict, the technical features mentioned in the various embodiments can be combined in any way. The present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A pressure buffer device for cementing plugs, comprising: The body (1) is constructed as a hollow cylindrical structure, and a first drain hole (11) and a connecting section (12) constructed to be connected to the rubber plug (200) are provided on the body (1). The protective cylinder (3) is a hollow cylindrical structure, fitted onto the outside of the main body (1), and includes a third drain hole (31) opened on the protective cylinder (3); and The actuating part (2) is located between the main body (1) and the protective cylinder (3), including a piston (21) and a spring (22) located above the piston (21), and a second drain hole (211) is provided on the piston (21). The main body (1) includes a working section (13), a carrying section (14), and a tail section (15) connected in order from bottom to top with increasing outer diameters. The protective cylinder (3) abuts against the lower end face of the tail section (15). The actuating part (2) is disposed inside the actuating chamber (23) between the protective cylinder (3) and the working section (13). The spring (22) is connected to the lower end face of the carrying section (14). A sealing assembly (4) is provided between the piston (21) and the body (1), between the piston (21) and the protective cylinder (3), and between the protective cylinder (3) and the body (1). The sealing assembly (4) includes a shaped ring assembly (41) and a first sealing ring (42) disposed between the body (1) and the piston (21) and respectively located below and above the first drain hole (11). The shaped ring assembly (41) includes a shaped ring (411) and two retaining rings (412) located on the upper and lower sides of the shaped ring (411). The shaped ring (411) is constructed with a transverse cross section of an "Ω" shape. The retaining rings (412) are either "L"-shaped retaining rings with an "L"-shaped cross section or "T"-shaped retaining rings with a "T"-shaped cross section. The piston (21) is configured to compress the spring (22) and move upward in response to abnormal cementing pressure, so that the first drain hole (11), the second drain hole (211) and the third drain hole (31) are connected to perform pressure relief operation.

2. The pressure buffer device for cementing plugs according to claim 1, characterized in that: An auxiliary hole (17) is provided on the main body (1) to connect the central cavity (16) of the main body (1) with the action chamber (23) through the side wall of the main body (1).

3. The pressure buffer device for cementing plugs according to claim 2, characterized in that: The connecting segment (12) is disposed below the working segment (13), and the connecting segment (12) is configured to have an outer diameter smaller than that of the working segment (13).

4. The pressure buffer device for cementing plugs according to claim 3, characterized in that: An annular groove (32) is provided on the inner wall of the protective cylinder (3), and the third drain hole (31) is configured to communicate with the annular groove (32).

5. The pressure buffer device for cementing plugs according to claim 4, characterized in that: The sum of the flow areas of all the third drain holes (31), the sum of the flow areas of all the first drain holes (11), and the sum of the flow areas of all the second drain holes (211) are all configured to be no less than the flow area of ​​the body (1).

6. The pressure buffer device for cementing plugs according to any one of claims 1 to 5, characterized in that: The irregular ring assembly (41) is configured to remain within the sealing stroke of the irregular ring assembly (41) when the pressure relief operation is performed at the second vent hole (211).

7. The pressure buffer device for cementing plugs according to claim 6, characterized in that: The piston (21) is constructed with a surface microtextured.

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