A lower sealer

Abstract

The present application relates to a lower sealer, comprising a lower sealer inner hole, a lower annular sealing piece arranged in the lower sealer inner hole, and a sealing sleeve arranged above the lower annular sealing piece and capable of moving up and down, the lower annular sealing piece is used for sealing with the smooth outer wall of the insert pipe through circumferential sealing cooperation, and the lower sealer is provided with a sealer liquid inlet hole arranged above the lower annular sealing piece and used for connecting the set oil production layer and the central channel. The lower sealer provided by the present application is used for sealing with the smooth outer wall of the insert pipe through circumferential sealing cooperation, and the sealing sleeve capable of closing / opening the sealer liquid inlet hole is further arranged in the lower sealer, so that the two functions of sealing and communication are realized, the sealing structure in the insert pipe is better protected, and the service life of the sealing structure in the insert pipe is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of oilfield mechanical exploitation water finding and plugging technology, and particularly relates to a lower sealing device used in a release outer tube of a pipe string for pipe insertion water finding and plugging. BACKGROUND

[0002] In the process of oilfield development, especially in the later stage of water injection development, the comprehensive water cut gradually rises, and the interlayer contradiction becomes more and more prominent. In order to understand the oil layer and stabilize oil and control water, the pipe string for pipe insertion water finding and plugging is often used for water finding and plugging operation. The pipe string for pipe insertion water finding and plugging in the prior art can be found in the patent document with the authorized announcement number CN 210919029 U, which discloses a "three-layer oil production water finding and plugging pipe string". The water finding and plugging pipe string includes a release outer tube and an inner tube. The release outer tube is provided with a central passage for the insertion of the inner tube. The release outer tube includes two packers distributed in upper and lower positions, i.e., an upper packer and a lower packer. The two packers are used to divide the release outer tube into an upper section, a middle section and a lower section, and simultaneously divide three oil production layers, i.e., an upper oil production layer, a middle oil production layer and a lower oil production layer. The sections of the release outer tube are respectively provided with oil inlet channels which communicate the oil production layers and the central passage. The inner tube includes sealing insertion pipes distributed in upper and lower positions, i.e., No. 1 sealing insertion pipe to No. 4 sealing insertion pipe. The inner tube is provided with a central passage. The central passage is provided with a pumping unit. The inner tube further includes a screen pipe between No. 2 sealing insertion pipe and No. 3 sealing insertion pipe. The screen pipe hole of the screen pipe forms an insertion pipe liquid inlet hole which communicates with the central passage in the inner tube. The release outer tube is provided with outer sealing cylinders in the central passage, i.e., an upper outer sealing cylinder and a lower outer sealing cylinder, which are used to cooperate with the sealing insertion pipes. Specifically, the outer periphery of the sealing insertion pipe is provided with a sealing ring, and the outer sealing cylinder has an inner peripheral surface which is used to sealingly cooperate with the sealing ring. In use, the inner tube is lifted and lowered. By changing the position of the screen pipe in the central passage and the sealing cooperation formed by the corresponding insertion of the sealing insertion pipe and the outer sealing cylinder, the specified oil production layer among the upper oil production layer, the middle oil production layer and the lower oil production layer can be produced, and the specified oil production layer among the upper oil production layer, the middle oil production layer and the lower oil production layer can be plugged.

[0003] As can be seen from the above, the four sealing insertion pipes on the inner tube of the pipe string for pipe insertion water finding and plugging in the prior art cooperate with the two outer sealing cylinders on the release outer tube to achieve the plugging and separation of each oil layer on the upper and lower sides of the packer. However, it is found in actual work that the sealing rings on the outer periphery of the four sealing insertion pipes are easily damaged by friction with the wellbore wall during the lowering of the inner tube into the well, which in turn leads to the problem of water finding and plugging failure. Therefore, the sealing structure in the pipe string for pipe insertion water finding and plugging in the prior art is easily damaged, has a short service life and poor reliability. SUMMARY

[0004] The purpose of the present application is to provide a lower sealing device to improve the durability and reliability of the sealing structure in the pipe string for pipe insertion water finding and plugging.

[0005] The lower sealer is used for being installed in the releasing outer pipe of the plug string, and comprises a lower sealer inner hole, which is used for being inserted by the plug string as a part of the central passage in the releasing outer pipe, and is provided with a lower annular sealing element and a sealing sleeve which is above the lower annular sealing element and can move up and down, the lower annular sealing element is used for sealing with the smooth outer wall of the plug string through the circumferential sealing cooperation, and the sealing sleeve is provided with a sealer liquid inlet hole which is above the lower annular sealing element and is used for connecting the set production layer and the central passage; the sealing sleeve moves up and down and has an upper position which closes the sealer liquid inlet hole and a lower position which opens the sealer liquid inlet hole, the upper part of the sealing sleeve and the upper part of the lower sealer are connected through a force failure connection structure, the outer wall of the lower part of the sealing sleeve and the inner wall of the middle part of the lower sealer are respectively provided with corresponding elastic clamping structures, the sealing sleeve in the lower position is fixed together with the middle part of the lower sealer through the elastic clamping structure, the inner wall of the sealing sleeve is provided with a force failure supporting structure which protrudes inward and is used for being pushed by the downward moving plug string to make the sealing sleeve bear downward force, the force limit value of the force failure connection structure is smaller than the force limit value of the force failure supporting structure, so that: when the plug string pushes the force failure supporting structure downward, the force failure connection structure fails first, and the sealing sleeve moves from the upper position to the lower position, and after the sealing sleeve moves to the lower position, the force failure supporting structure fails, and the plug string can continue to go down.

[0006] The lower sealer provided by the application is used for sealing with the smooth outer wall of the plug string through the circumferential sealing cooperation, and the sealing assembly is no longer needed to be installed on the plug string, so that the rubber seal outside the sealing assembly can be prevented from being damaged by the friction with the wellbore wall during the lowering process, and the sealing sleeve which can close / open the sealer liquid inlet hole is further provided in the lower sealer, so that after the lower sealer and the releasing outer pipe are combined through the mechanical action, the two functions of sealing and connecting are realized, the hydraulic seat can be ensured to be pressed and the packer can be ensured to be closed after the releasing string is lowered to the position, and the internal sealing structure can be better protected, so that the service life of the sealing structure in the plug string is improved.

[0007] Further, the lower sealer comprises an upper connecting head, a middle connecting body and a lower connecting head which are distributed upward and downward, the upper connecting head, the middle connecting body and the lower connecting head are all hollow pipe bodies and form the lower sealer inner hole in the lower sealer, and the sealer liquid inlet hole is arranged on the upper connecting head.

[0008] Further, the upper end of the upper connecting head is provided with an internal thread which is used for connecting with the connecting pipe, and the lower end of the lower connecting head is provided with an external thread which is used for connecting with the connecting pipe.

[0009] Further, the elastic clamping structure is a corresponding snap spring and a snap spring groove.

[0010] Further, the snap spring slot is arranged on the middle connecting body.

[0011] Further, the stress failure connecting structure is a shear pin, and a shear pin hole for accommodating the shear pin is arranged on the upper connecting head and the sealing sleeve.

[0012] Further, the stress failure supporting structure is a shear pin.

[0013] Further, the lower annular sealing element is arranged in the lower connecting head.

[0014] Further, the lower annular sealing element comprises an annular base and a sealing rubber ring, and the sealing rubber ring is arranged on the inner circumferential surface of the annular base.

[0015] Further, the sealing rubber ring and the ring groove on the inner circumferential surface of the annular base are combined by vulcanization, the annular base is a vulcanized steel part, and the sealing rubber ring is vulcanized rubber. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 is a use state diagram of an embodiment of the lower sealing device of the present application used in a pipe string for finding and plugging water;

[0017] Figure 2 is Figure 1 a structural schematic diagram of the pipe string for finding and plugging water;

[0018] Figure 3 is a structural schematic diagram of an embodiment of the lower sealing device of the present application;

[0019] in the diagram:

[0020] 1, oil pump; 2, anchor; 3, pipe string; 31, pipe string liquid inlet hole; 32, first pipe string; 33, cone head; 34, connecting head; 35, second pipe string; 4, release device; 5, upper sealing device; 6, upper packer; 7, lower sealing device; 71, sealing device liquid inlet hole; 72, upper connecting head; 73, middle connecting body; 74, lower connecting head; 75, shear pin; 76, sealing sleeve; 77, shear pin; 78, snap spring; 79, snap spring slot; 80, annular base; 81, sealing rubber ring; 8, safety joint; 9, lower packer; 10, ball seat; 11, screen pipe; 12, plug; 100, casing; 101, upper oil production layer; 102, middle oil production layer; 103, lower oil production layer. DETAILED DESCRIPTION

[0021] An embodiment of a lower sealing device of the present application is shown in Figures 1-3 Since the lower sealing device of the present application is a component of the release outer pipe of the pipe string for finding and plugging water, in order to facilitate understanding, before the specific structure of the lower sealing device is introduced, the structure of the pipe string for finding and plugging water is introduced first through Figure 1 ,Figure 2 To introduce the application of the lower sealing device 7 of the string for finding and plugging water, the string for finding and plugging water comprises a releasing outer tube and an inner tube, the releasing outer tube is used for being fixed in the casing 100 of the oil well, the releasing outer tube is provided with a central passage for inserting the inner tube, and the inner tube is used for being inserted in the releasing outer tube.

[0022] The releasing outer tube comprises two packers distributed in upper and lower positions, i.e. an upper packer 6 and a lower packer 9, the upper packer 6 and the lower packer 9 are connected together through a connecting pipe, the two packers are in sealing cooperation with the casing 100, so that the packers divide the releasing outer tube into an upper section, a middle section and a lower section from the outside, and simultaneously divide the oil production layers into three oil production layers corresponding to the sections of the releasing outer tube, i.e. an upper oil production layer 101, a middle oil production layer 102 and a lower oil production layer 103, and each section of the releasing outer tube is respectively provided with an oil inlet passage, i.e. an upper oil inlet passage, a middle oil inlet passage and a lower oil inlet passage, and each oil inlet passage is used for connecting the oil production layer corresponding to each section of the releasing outer tube with the central passage. The releasing outer tube is further provided with a releaser 4, a safety joint 8, a ball seat 10, a screen pipe 11 and a plug 12, which belong to the prior art.

[0023] The releasing outer tube further comprises sealing devices for sealing cooperation with the string for finding and plugging water, i.e. an upper sealing device 5 and a lower sealing device 7, the sealing devices are provided with annular sealing members, i.e. an upper annular sealing member installed in the upper sealing device 5 and a lower annular sealing member installed in the lower sealing device 7, the upper sealing device 5 and the lower sealing device 7 are respectively located on the upper side and the lower side of the upper packer 6, the upper oil inlet passage is located above the upper sealing device 5, and the lower oil inlet passage is located below the lower sealing device 7, in this embodiment, the middle oil inlet passage is a sealing device liquid inlet hole 71 provided on the lower sealing device 7 and located above the lower annular sealing member, i.e. the middle oil inlet passage is located between the upper annular sealing member and the lower annular sealing member. That is, the upper annular sealing member of the upper sealing device 5 and the lower annular sealing member of the lower sealing device 7 divide the releasing outer tube into three sections from the inside, and the aforementioned oil inlet passages (the upper oil inlet passage, the middle oil inlet passage and the lower oil inlet passage) are respectively located on the sections divided by the upper sealing device 5 and the lower sealing device 7.

[0024] The inner tube is provided with a central passage, the central passage is used as an oil pumping passage, the central passage is provided with an oil pumping pump 1, the inner tube comprises an anchor 2 and a string for finding and plugging water 3 located at the lower end of the inner tube, the lowermost end of the string for finding and plugging water 3 is closed, and the string for finding and plugging water 3 is provided with a string liquid inlet hole 31 communicating with the central passage. Figure 2As shown, the insert pipe 3 is a hollow pipe, and the insert pipe 3 is provided with sealing fitting sections formed by smooth outer walls with equal outer diameters on the upper and lower sides of the insert pipe liquid inlet hole 31, the sealing fitting sections include upper sealing fitting sections and lower sealing fitting sections, the sealing fitting sections of the insert pipe 3 are in circumferential sealing fitting with annular sealing members in the upper sealing device 5 and the lower sealing device 7 to realize sealing, the sealing fitting sections are used for the cooperation of the annular sealing members (the annular sealing members include upper annular sealing members installed in the upper sealing device 5 and lower annular sealing members installed in the lower sealing device 7) in the upper sealing device 5 and the lower sealing device 7 when the inner pipe is lifted up and lowered down, and the sealing fitting sections are used for blocking and separating the corresponding oil production layers on both sides of the packer of the corresponding free pipe.

[0025] The embodiment of the lower sealing device 7 of the present application is applied to the insert pipe water finding and plugging pipe column, and when the insert pipe 3 is inserted into the upper sealing device 5 and the lower sealing device 7, the following working modes are used:

[0026] (a) The insert pipe liquid inlet hole 31 is located below the lower annular sealing member of the lower sealing device 7, the insert pipe liquid inlet hole 31 is communicated with the lower oil production channel to produce oil for the lower oil production layer 103;

[0027] (b) The insert pipe liquid inlet hole 31 is located above the middle liquid inlet channel and below the upper annular sealing member of the upper sealing device 5, the insert pipe liquid inlet hole 31 is communicated with the middle oil production channel (the sealing device liquid inlet hole 71) to produce oil for the middle oil production layer 102;

[0028] (c) The insert pipe liquid inlet hole 31 is located above the upper annular sealing member of the upper sealing device 5, the insert pipe liquid inlet hole 31 is communicated with the upper oil production channel to produce oil for the upper oil production layer 101.

[0029] The structure of the lower sealing device 7 is shown in Figure 3 The lower sealing device 7 includes upper connecting heads 72, a middle connecting body 73 and lower connecting heads 74 which are distributed upward and downward, the upper connecting heads 72, the middle connecting body 73 and the lower connecting heads 74 are hollow pipe bodies to form a lower sealing device 7 inner hole in the lower sealing device 7, the lower sealing device 7 inner hole can be inserted by the insert pipe 3 as a part of the central channel in the free pipe. The lower sealing device 7 inner hole is provided with sealing sleeves 76 and lower annular sealing members which are distributed upward and downward.

[0030] The upper and lower ends of the middle connecting body 73 are threadedly connected with the upper connecting heads 72 and the lower connecting heads 74 respectively, the sealing device liquid inlet hole 71 is arranged on the upper connecting heads 72, the upper end of the upper connecting heads 72 is provided with an internal thread for connecting with a connecting pipe, and the lower end of the lower connecting heads 74 is provided with an external thread for connecting with the connecting pipe.

[0031] The sealing sleeve 76 is installed in the middle upper part of the inner hole of the lower packer 7, in the upper connecting head 72 and the middle connecting body 73, and can move up and down to have an upper position to close the packer liquid inlet hole 71 and a lower position to open the packer liquid inlet hole 71. The upper part of the sealing sleeve 76 and the upper connecting head 72 are correspondingly provided with a shear pin hole, the sealing sleeve 76 in the upper position is fixed with the upper connecting head 72 through the shear pin 75, the outer wall of the lower part of the sealing sleeve 76 and the inner wall of the middle connecting body 73 are respectively provided with corresponding snap springs 78 and snap spring grooves 79, the sealing sleeve 76 in the lower position is fixed with the middle connecting body 73 through the snap of the snap spring 78 and the snap spring groove 79, the inner wall of the sealing sleeve 76 is provided with a shear pin 77 protruding inward, the shear pin 77 is used to be pushed by the downwardly moving insertion pipe 3 to make the shear pin 77 and the sealing sleeve 76 bear downward force, the shear limit value of the shear pin 75 is less than the shear limit value of the shear pin 77, so that: the shear pin 75 and the shear pin 77 fail in sequence when the insertion pipe 3 pushes the shear pin 77 downward, the sealing sleeve 76 will move from the upper position to the lower position after the shear pin 75 fails, and the shear pin 77 fails after the sealing sleeve 76 moves to the lower position, so that the insertion pipe 3 can continue to descend. The function of the sealing sleeve 76 is that the sealing sleeve 76 is fixed with the lower packer 7 through the shear pin 75, the lower packer 7 is in a sealed state before the insertion pipe 3 is inserted into the packer liquid inlet hole, and the inside and outside are not connected, which can ensure that the release pipe string is lowered to the position and the packer 6 and the lower packer 9 are sealed by the hydraulic seat.

[0032] The lower annular sealing element is installed in the lower connecting head 74, and includes an annular base 80 and a sealing rubber ring 81. In this embodiment, the sealing rubber ring 81 is combined with the annular groove on the inner circumferential surface of the annular base 80 by vulcanization, so that the annular base 80 is a vulcanized steel part, and the sealing rubber ring 81 is vulcanized rubber. The sealing rubber ring 81 is tightly adhered to the inner circumferential surface of the annular base 80, and is not easy to fall off and damage under the pressure difference on both sides of the sealing rubber ring 81 when the insertion pipe 3 is lifted or lowered, thereby prolonging the effective period. The outer circumferential surface of the annular base 80 is provided with a sealing ring in sealing cooperation with the inner circumferential surface of the lower connecting head 74.

[0033] The working principle of the lower annular sealing member is as follows: when the cannula 3 is inserted into the lower sealing device 7, the cannula 3 enters into contact with the shear pin 77 of the upper connector 72 and is pressurized, the shear pin 75 is first sheared, the sealing sleeve 76 continues to descend with the cannula 3, the liquid inlet hole 71 of the sealing device is opened, the liquid can flow into and out through the liquid inlet hole 71, and the inside and outside are communicated. The sealing sleeve 76 continues to descend with the cannula 3, the clamping spring 78 enters into the clamping spring slot 79, and the sealing sleeve 76 is fixed, the shear pin 77 is sheared, the cannula 3 continues to descend, enters into the lower annular sealing member, the sealing fitting section of the outer wall of the cannula 3 is in rubber contact with the sealing rubber ring 81 of the lower annular sealing member, and sealing is realized, the upper and lower sides of the lower annular sealing member in the lower sealing device 7 are sealed and separated into two sealing pressure systems, and the upper part of the lower sealing device 7 is communicated with the inside and outside through the liquid inlet hole 71. When the cannula 3 is pulled out of the lower sealing device 7, the lower sealing device 7 becomes a pressure system.

[0034] In addition, in other embodiments of the present application, the shear pin for fixing the sealing sleeve can also be replaced by other common force failure connection structures in the art, such as a thin filament screw that can be force failure. The embodiments formed by the above listed or similar simple replacement or obvious deformation also belong to the embodiments of the technical solutions of the present application.

Claims

1. A lower seal for installation in a release outer casing of a snubbing string, characterized in that, The lower sealing device includes a lower sealing device inner hole, which is used as a part of the central passage in the releasing outer tube and can be inserted by the insertion tube (3), and a lower annular sealing element and a sealing sleeve (76) above the lower annular sealing element and movable up and down are arranged in the lower sealing device inner hole, the lower annular sealing element is used to seal with the smooth outer wall of the insertion tube (3) through the circumferential sealing cooperation, and a sealing device liquid inlet hole (71) above the lower annular sealing element for connecting the set production layer and the central passage is arranged on the upper sealing device; the sealing sleeve (76) is movable up and down to have an upper position for closing the sealing device liquid inlet hole (71) and a lower position for opening the sealing device liquid inlet hole (71), the upper part of the sealing sleeve (76) and the upper part of the lower sealing device are connected through a force failure connection structure, the outer wall of the lower part of the sealing sleeve (76) and the inner wall of the middle part of the lower sealing device are respectively provided with corresponding elastic clamping structures, the sealing sleeve (76) in the lower position is fixed together with the middle part of the lower sealing device through the elastic clamping structure clamping, and the inner wall of the sealing sleeve (76) is provided with a force failure support structure protruding inward, which is used to be pushed by the downwardly moved insertion tube (3) to make the sealing sleeve (76) downwardly stressed, the force limit value of the force failure connection structure is smaller than the force limit value of the force failure support structure, so that: when the insertion tube (3) pushes the force failure support structure downwardly, the force failure connection structure fails first, so that the sealing sleeve (76) moves from the upper position to the lower position, and after the sealing sleeve (76) moves to the lower position, the force failure support structure fails, so that the insertion tube (3) can continue to descend.

2. The undersealer of claim 1, wherein, The lower sealing device includes an upper connecting head (72), a middle connecting body (73), and a lower connecting head (74) distributed upward and downward, the upper connecting head (72), the middle connecting body (73), and the lower connecting head (74) are all hollow pipe bodies to form the lower sealing device inner hole in the lower sealing device; and the sealing device liquid inlet hole (71) is arranged on the upper connecting head (72).

3. The undersealer of claim 2, wherein, The upper end of the upper connecting head (72) is provided with an internal thread for connecting with a connecting pipe, and the lower end of the lower connecting head (74) is provided with an external thread for connecting with the connecting pipe.

4. The undersealer of claim 2, wherein, The elastic clamping structure is a corresponding clamping spring (78) and a clamping spring groove (79).

5. The undersealer of claim 4, wherein, The clamping spring groove (79) is arranged on the middle connecting body (73).

6. The undersealer of claim 2, wherein, The force failure connection structure is a shear pin (75), and the upper connecting head (72) and the sealing sleeve (76) are correspondingly provided with shear pin holes for passing the shear pin (75).

7. The undersealer of claim 2, wherein, The force failure support structure is a shear pin (77).

8. The undersealer of claim 2, wherein, The lower annular sealing element is arranged in the lower connecting head (74).

9. The undersealer of any of claims 1-8, wherein, The lower annular sealing element includes an annular base (80) and a sealing rubber ring (81), and the sealing rubber ring (81) is arranged on the inner circumferential surface of the annular base (80).

10. The undersealer of claim 9, wherein, The sealing rubber ring (81) and the annular groove on the inner circumferential surface of the annular base (80) are combined by vulcanization, the annular base (80) is a vulcanized steel part, and the sealing rubber ring (81) is vulcanized rubber.

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