Cement injection valve for cementing plug in underground operation

Abstract

The utility model relates to a cement injection valve of a cement injection plug for underground operation, and belongs to the technical field of cement injection devices. The cement injection valve of the underground operation cement injection plug comprises an outer cylinder, an inner cylinder fixed in the outer cylinder through a shear pin and a releasing type plugging piece matched with the inner cylinder, and a first stopping structure for preventing the inner cylinder from falling out of the outer cylinder is arranged at the lower end of the outer cylinder. A circulation opening which is closed by the inner cylinder and opened due to the fact that the inner cylinder moves towards the first stop structure after the shear pin is broken is formed in the cylinder wall of the outer cylinder; and a second stopping structure for preventing the releasing type plugging piece from falling out of the inner cylinder is arranged in the inner cylinder. According to the cement injection valve of the underground operation cement injection plug, the injection accuracy of displacement liquid can be improved, and the situation that the quality of the cement plug is unqualified due to the fact that displacement slurry flows out and is mixed with cement slurry in the process of lifting a pipe column can be avoided.

Description

Technical Field

[0001] The utility model relates to a cement injection valve for cementing plugs in underground operations, belonging to the technical field of cementing devices. Background Art

[0002] The underground operation cement plugging process is to replace a certain amount of cement slurry into the casing or a certain part of the wellbore to form a new artificial well bottom that meets the injection and production needs or to temporarily close a certain well section to meet the process. Specifically, in the underground operation process, the wellbore is injected with suspended cement plugs, usually using a smooth oil pipe injection, such as Figure 1 As shown, after the tubing string 100 is lowered, the tubing string 100 is filled with the well-killing fluid 101, and then the front spacer fluid 102 is injected, and the well-killing fluid 101 is reversed out of the annulus; then the cement slurry 103 is injected, the annulus continues to discharge liquid, and the front spacer fluid 102 moves upward along the annulus to form an upper liquid plug 104; then the rear spacer fluid 105 is injected, the annulus continues to discharge liquid, and the cement slurry 103 moves upward along the annulus; finally, the well-killing fluid 101 is replaced, the annulus continues to discharge liquid, and the cement slurry 103 all enters the annulus; the well-killing fluid 101 is injected to displace it in place, the cement slurry 103 all enters the annulus, and the rear spacer fluid 105 forms a lower liquid plug 106; after the cement slurry 103 is replaced to the designed position, the tubing string is lifted to above the designed gray surface position, and then the well is circulated to wash out the cement slurry 103 remaining in the tubing string, and finally the tubing string is lifted to a safe position, the wellhead is seated, the well is filled with well-killing fluid, and the well is shut in for solidification.

[0003] For high-pressure gas wells, due to the high formation pressure, in order to ensure well control safety, high-density mud needs to be injected to balance the formation pressure before the suspended cement plug is injected into the wellbore. In the process of injecting cement plugs into the wellbore in a mud well-killing fluid environment, since the displacement mud (well-killing fluid) enters the cement injection truck through the mud pump, foam is easily generated. There is no reliable means to accurately measure the amount of displacement mud injected. The displacement may be insufficient or over-displaced. If the displacement is insufficient, it is easy to cause the cement slurry to not be completely covered by the rear isolation fluid. In this case, since the cement slurry fails to form an effective isolation with the well-killing fluid, the cement slurry will be eroded by the well-killing fluid; and when over-displaced, the tubing is completely filled with displacement mud. In the subsequent process of lifting the oil pipe, the displacement mud in the tubing flows out with the tubing lifting and mixes into the cement slurry in large quantities, and the cement slurry will also be eroded by the displacement mud. Therefore, no matter the replacement amount is insufficient or excessive, the cement slurry is easily eroded, resulting in the cement slurry not being able to solidify normally and forming an effective ash column, or the ash plug thickness and strength not meeting the design requirements, resulting in ash column honeycomb phenomenon. Utility Model Content

[0004] The utility model aims to provide a mud injection valve for cement plugging in underground operation, so as to solve the problem of insufficient or excessive mud displacement in the existing cement plugging process in underground operation.

[0005] In order to achieve the above purpose, the technical solution adopted by the utility model is:

[0006] A cement injection valve for cement plugging in underground operations comprises an outer tube, an inner tube fixed in the outer tube by shear pins, and a throw-away plugging piece cooperating with the inner tube, wherein the lower end of the outer tube is provided with a first stop structure for preventing the inner tube from falling out of the outer tube, and the tube wall of the outer tube is provided with a circulation port which is closed by the inner tube and is opened when the shear pins break due to the inner tube moving toward the first stop structure; and the inner tube is provided with a second stop structure for preventing the throw-away plugging piece from falling out of the inner tube.

[0007] Furthermore, the first stopping structure is a first limiting inner flange arranged on the inner side of the outer tube.

[0008] Furthermore, the drop-type blocking member includes a stabilizing rod and a supporting portion arranged on the stabilizing rod for cooperating with the second stopping structure. The stabilizing rod is also provided with an inner cylinder blocking structure located upstream of the supporting portion for blocking the inner cylinder channel.

[0009] Furthermore, the inner cylinder sealing structure includes a leather cup-type sealing gasket sleeved on the upper end of the stabilizing rod.

[0010] Furthermore, the second stopping structure is a second limiting inner flange arranged on the inner side of the inner tube, the supporting portion is a supporting ring arranged at the lower end of the stabilizing rod, and the side of the supporting ring facing away from the leather cup type sealing gasket forms a drop-type sealing member for abutting against the second limiting inner flange.

[0011] Furthermore, the outer cylinder is provided with a shear nail hole for the shear nail to pass through, and the inner cylinder is provided with a shear nail insertion hole corresponding to the shear nail hole.

[0012] Furthermore, a sealing matching structure is provided between the inner cylinder and the outer cylinder.

[0013] Furthermore, an annular groove is arranged on the inner wall of the outer cylinder, and the annular groove is located above the circulation port; the sealing matching structure includes the outer wall surface of the inner cylinder and a sealing ring arranged in the annular groove.

[0014] Furthermore, an inverted cone surface is provided at the upper end of the inner cylinder.

[0015] Furthermore, there are multiple circulation ports evenly distributed along the circumference of the outer cylinder.

[0016] The utility model discloses a cement injection valve for cement plugging in underground operation, which is a pioneering invention. When in use, the cement injection valve is connected to the bottom of the pipe column. Before injecting displacement mud, a throw-away plugging piece is put into the wellbore, and displacement fluid is injected. The throw-away plugging piece moves downward into the inner tube and stops moving downward at the second stop structure of the inner tube. The pump pressure at the wellhead increases, and the pump is stopped to lift the pipe column to the well washing depth. The pump is turned on to continue injecting displacement mud, and the pressure in the inner tube continues to increase, and then the shear pins are sheared and broken by the inner and outer tubes. The inner tube carries the throw-away plugging piece to the first stop structure of the outer tube and stops moving downward. The circulation port of the outer tube is opened to carry out circulation well washing to wash out the excess mortar in the wellbore.

[0017] During the cement plugging construction process, the completion of the rear isolation fluid displacement can be indicated by the wellhead pump pressure, and there is no need to measure the displacement fluid volume on the ground, thereby avoiding excessive or insufficient displacement fluid volume, improving the accuracy of the displacement fluid injection volume, and thus improving the success rate of cement plugging. In addition, when the cement slurry pipe column is lifted after the displacement is completed, the utility model, on the one hand, prevents the displacement mud from flowing out of the pipe column and mixing with the cement slurry, and on the other hand, keeps the outer tube circulation port in a closed state, and the oil pipe is not connected to the casing, so as to prevent the displacement fluid from entering the wellbore and contaminating the cement slurry, thereby ensuring the quality of the cement plug and further improving the success rate of cement plugging. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A schematic diagram of the process of injecting suspended cement plug into a wellbore in the background technology;

[0019] Figure 2 A schematic diagram of the structure of a cement injection valve for cementing plugs in underground operations according to Example 1 of the utility model;

[0020] Figure 3 This is a schematic diagram of the cement injection valve of the underground operation cementing plug of Example 1 of the utility model when the shear pins are not broken during use;

[0021] Figure 4 This is a schematic diagram of the cement injection valve of the underground operation cementing plug of Example 1 of the utility model after the shear nail is broken during use;

[0022] Among them, 100-tubing string; 101-well killing fluid; 102-front isolation fluid; 103-cement slurry; 104-upper liquid plug; 105-rear isolation fluid; 106-lower liquid plug; 1-outer tube; 2-inner tube; 3-rubber plug; 4-internal thread; 5-shear pin; 6-shear pin hole; 7-first limit inner flange; 8-second limit inner flange; 9-circulation port; 10-sealing ring; 11-stabilizing rod; 12-support ring; 13-leather cup type sealing gasket; 14-first limit ring; 15-second limit ring. DETAILED DESCRIPTION

[0023] The technical concept of the utility model is essentially to add a ash injection valve between the rear isolation fluid and the displacement fluid, so that after the ash injection valve blocks the injection channel, it indicates that the displacement is in place. On the one hand, it solves the problem of inaccurate displacement amount, and on the other hand, it avoids the displacement fluid (mud) from flowing out of the pipe column and mixing with cement slurry when the pipe column is lifted (especially when high-density mud well-killing fluid is required), thereby ensuring that the thickness and strength of the cement plug meet the design requirements.

[0024] Furthermore, in order to realize the circulation well washing function, the utility model designs an inner and outer tube shear nail composite structure, and a circulation port is arranged on the outer tube. Before the displacement construction, the circulation port is closed by the inner tube to ensure that various working fluids are smoothly injected into the wellbore; after the ash injection valve shows that the displacement is completed, the pipe string can be lifted to the well washing depth, and after continuing to pump and cut off the shear nails, the inner tube descends to open the circulation port, so that circulation well washing can be carried out to wash out the excess mortar in the wellbore, thus completing the cement plug construction process.

[0025] Specifically, the utility model realizes the above process through an outer cylinder, an inner cylinder and a throw-away sealing piece cooperating with the inner cylinder. The inner cylinder is fixed in the outer cylinder by shear nails. A circulation port is provided on the outer cylinder, which is closed by the inner cylinder before the shear nails are cut off. After the shear nails are cut off, the inner cylinder moves downward to open the circulation port. A first stopping structure is provided on the outer cylinder to prevent the inner cylinder from falling out, and a second stopping structure is provided on the inner cylinder to prevent the throw-away sealing piece from falling out of the inner cylinder.

[0026] The technical solution of the utility model is further described below in conjunction with specific implementation methods.

[0027] Example 1

[0028] The cement injection valve of the underground operation cement injection plug of this embodiment is as follows: Figure 2 to Figure 4 As shown, Figure 3 and Figure 4 The ash injection valve of the present embodiment comprises an outer cylinder 1, an inner cylinder 2 fixed in the outer cylinder by shear nails 5, and a rubber plug 3 used in conjunction with the inner cylinder 2.

[0029] The outer tube 1 is evenly provided with 4 shear nail holes 6 along the circumferential direction, and the outer wall of the inner tube 2 is provided with shear nail insertion holes corresponding to each shear nail hole 6. When the inner tube 2 is placed in the inner tube 1 during use, the shear nails 5 are inserted into the shear nail insertion holes after passing through the shear nail holes 6 to fix the inner tube 2 in the outer tube 1. The inner tube 2 and the outer tube 1 are clearance-matched, and can move in the outer tube 1 after the shear nails 5 break. The upper end of the outer tube 1 is provided with an internal thread 4 for connecting the pipe column, and the inner side of the lower end is provided with a first limiting inner flange 7, which can prevent the inner tube 2 from moving out of the outer tube 1 after the shear nails 5 break; in other embodiments of the utility model, the first limiting inner flange can also be replaced by two symmetrical limiting blocks arranged on the inner side of the other end of the outer tube.

[0030] Four square circulation ports 9 are evenly arranged along the circumference of the outer cylinder 1. The circulation ports 9 are arranged between the internal thread 4 and the shear nail hole 6. The minimum distance between the edge of the circulation port 9 and the first limit inner flange 7 is greater than the length of the inner cylinder 2. The four corners of the circulation port 9 can be rounded to reduce the flow resistance of the liquid during the circulation during the well washing. In other implementation situations, the circulation port on the outer cylinder is long strip or round, and the number of the circulation ports is 3 or 5.

[0031] The inner wall of the upper end of the outer cylinder 1 is provided with an annular groove, and a sealing ring 10 is provided in the annular groove. The sealing ring 10 in the annular groove and the outer wall surface of the inner cylinder 2 form a sealing matching structure, and the annular groove is located above the circulation port 9 and below the internal thread 4. The sealing ring 10 can prevent particles in the cement slurry from entering between the inner cylinder 2 and the outer cylinder 1, thereby increasing the resistance of the inner cylinder 2 to move in the outer cylinder 1 after the shear nail 5 breaks, and because the inner cylinder 2 covers the circulation port 9 on the outer cylinder 1, the fluid will not flow between the outer cylinder 1 and the inner cavity of the inner cylinder 2 through the circulation port 9 before the shear nail 5 breaks.

[0032] The upper end of the inner cylinder 2 is the plug entry end, and the upper end is provided with an inverted cone surface, which can reduce the plug entry resistance. The inner side of the lower end of the inner cylinder 2 is provided with a second limiting inner flange 8, which can prevent the plug 3 entering the inner cylinder 2 from moving out of the inner cylinder 2. In other embodiments of the utility model, the second limiting inner flange can also be replaced by two symmetrically arranged limiting blocks arranged on the inner side of the other end of the inner cylinder.

[0033] The rubber plug 3 is a drop-type plugging component, including a stabilizing rod 11, a support ring 12 and a leather cup-type sealing gasket 13. The support ring 12 is sleeved on one end of the stabilizing rod 11, and a threaded section is provided on the other end of the stabilizing rod 11. The threaded section is threadedly connected to a first limiting ring 14 and a second limiting ring 15. The leather cup-type sealing gasket 13 is sleeved outside the threaded section and is clamped and fixed by the first limiting ring 14 and the second limiting ring 15. The stabilizing rod 11 can prevent the rubber plug 3 from turning over during the downward movement in the pipe column. Since the leather cup-type sealing gasket 13 is a consumable part, it is clamped and fixed by the first limiting ring 14 and the second limiting ring 15, which facilitates the replacement of the leather cup-type sealing gasket 13. The support ring 12 and the stabilizing rod 11 are integrally formed plastic products, and the side of the support ring 12 away from the leather cup-type sealing gasket 13 is the abutment surface when the rubber plug 3 abuts against the second limiting inner flange 8. In other embodiments of the utility model, the leather cup seal 13, the threaded section, the first limiting ring 14 and the second limiting ring 15 on the rubber plug 3 can be omitted, and the sealing effect can be achieved only by the support ring abutting surface abutting against the second limiting inner flange.

[0034] When the cement injection valve of the underground operation cement injection plug of this embodiment is used, Figure 2As shown, the inner tube 2 is installed into the outer tube 1 and fixed with shear nails 5. After fixing, the outer tube 1 is connected to the bottom of the cement plug column through the internal thread 4 at the end and lowered to the designed cement plug depth. The front isolation fluid, cement slurry, and rear isolation fluid are injected in sequence according to the designed amount, and then the rubber plug is put in, and then the displacement fluid is injected. The rubber plug 3 moves down into the inner tube with the displacement fluid and stops moving down at the second limit inner flange 8 (as shown in FIG. Figure 3 As shown in the figure, the wellhead pump pressure starts to increase, and after the pump is stopped, the cement slurry pipe column is injected to the designed backwash or forward wash depth; the displacement fluid (i.e., well killing fluid) is continuously pumped, and thereafter the displacement fluid pressure in the inner tube 2 continues to increase. When it increases to a certain level, the shear pins 5 are sheared off by the inner tube 2 and the outer tube 1, and the inner tube 2 moves downward with the rubber plug 3 to the first limit inner flange 7 of the outer tube 1 and stops moving downward (as shown in the figure). Figure 4 As shown), the circulation port 9 on the outer tube 1 is opened, and then the well is circulated and washed to wash out the excess cement slurry in the wellbore. The pipe string is lifted to the designed depth and then waited for solidification, and the cement plugging construction is completed. In this process, when the rubber plug 3 seals the flow passage of the inner tube, the isolation fluid is basically completely injected into the wellbore, thereby avoiding the failure of cement plugging caused by the inability to measure or inaccurate measurement of the displacement fluid during injection; and because the circulation port on the outer tube is still in a closed state when the cement slurry pipe string is lifted after displacement, the oil pipe and the casing are not connected, thereby avoiding the displacement fluid from entering the wellbore to contaminate the cement slurry and causing the failure of cement plugging.

[0035] Example 2

[0036] The cement injection valve for cement plugs for underground operations in this embodiment is different from the cement injection valve for cement plugs for underground operations in Example 1 only in that the rubber plug in this embodiment is not provided with a support ring, but a disc-shaped support seat is provided at the end of the stabilizing rod away from the leather cup-type sealing gasket, and the disc-shaped support seat can also play a supporting role for the rubber plug.

Claims

1. A cement injection valve for cementing plugs in underground operations, characterized in that: The utility model comprises an outer cylinder, an inner cylinder fixed in the outer cylinder by shear nails, and a throw-away plugging piece cooperating with the inner cylinder, wherein the lower end of the outer cylinder is provided with a first stopping structure for preventing the inner cylinder from falling out of the outer cylinder, and the cylinder wall of the outer cylinder is provided with a circulation port which is closed by the inner cylinder and opened when the shear nails break and the inner cylinder moves toward the first stopping structure; and the inner cylinder is provided with a second stopping structure for preventing the throw-away plugging piece from falling out of the inner cylinder.

2. The cement injection valve for cement plugging in underground operations according to claim 1, characterized in that: The first stopping structure is a first limiting inner flange arranged on the inner side of the outer tube.

3. The cement injection valve for cement plugging in underground operations according to claim 1 or 2, characterized in that: The drop-type blocking member includes a stabilizing rod and a supporting portion arranged on the stabilizing rod for cooperating with a second blocking structure. The stabilizing rod is also provided with an inner cylinder blocking structure located upstream of the supporting portion for blocking the inner cylinder channel.

4. The cement injection valve for cement plugging in underground operations according to claim 3, characterized in that: The inner cylinder blocking structure comprises a leather cup type sealing gasket sleeved on the upper end of the stabilizing rod.

5. The cement injection valve for cement plugging in underground operations according to claim 4, characterized in that: The second stopping structure is a second limiting inner flange arranged on the inner side of the inner tube, and the supporting part is a supporting ring arranged at the lower end of the stabilizing rod. The side of the supporting ring facing away from the leather cup type sealing gasket forms a drop-type sealing part for abutting against the second limiting inner flange.

6. The cement injection valve for cement plugging in underground operations according to claim 1 or 2, characterized in that: The outer cylinder is provided with a shear nail hole for the shear nail to pass through, and the inner cylinder is provided with a shear nail insertion hole corresponding to the shear nail hole.

7. The cement injection valve for cementing plugs for underground operations according to claim 1 or 2, characterized in that: A sealing matching structure is arranged between the inner cylinder and the outer cylinder.

8. The cement injection valve for cement plugging in underground operations according to claim 7, characterized in that: An annular groove is arranged on the inner wall of the outer cylinder, and the annular groove is located above the circulation port; the sealing matching structure comprises the outer wall surface of the inner cylinder and a sealing ring arranged in the annular groove.

9. The cement injection valve for cement plugging in underground operations according to claim 1 or 2, characterized in that: The upper end of the inner cylinder is provided with an inverted cone surface.

10. The cement injection valve for cement plugging in underground operations according to claim 1 or 2, characterized in that: There are multiple circulation ports evenly distributed along the circumference of the outer cylinder.

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