Small wellbore soluble safety connector

Abstract

This utility model discloses a soluble release safety connector for small wells, comprising: an upper connector with symmetrical grooves on its middle outer wall; a lower connector, the upper part of which is fixed to the lower outer periphery of the upper connector by a shear pin, and the upper end having symmetrical tenons that are embedded in the grooves of the upper connector; a sealing bushing, the upper external thread section of which is connected to the internal thread at the lower end of the upper connector, the lower part of which is sealed to the lower inner wall of the upper connector, and the lower end of the sealing bushing is enlarged to form an outer step and is sealed to the lower inner wall of the lower connector; and a soluble release ring, located in the annular space between the middle inner wall of the lower connector and the outer wall of the sealing bushing, the upper inner periphery of which abuts against the middle outer periphery of the sealing bushing, the inner wall below the upper inner step of which has a gap with the middle outer wall of the sealing bushing and is flush with the lower inner wall of the lower connector, and the external thread of the lower outer periphery of the soluble release ring being connected to the internal thread above the inner step of the lower connector. This soluble release safety connector for small wells can ensure smooth release and reduce the risk of major overhauls.

Description

Technical Field

[0001] This utility model relates to a tool for releasing the hand from an oilfield water injection tubing string, and more particularly to a soluble release safety connector for small wellbore, belonging to the technical field of downhole tools for oil production. Background Technology

[0002] Small-bore water injection wells refer to wells with a smaller diameter than conventional wells, drilled using a drill bit smaller than ø152.4mm (6 inches) in a relatively long well section during the drilling process. Casing is then installed in the small-bore well, and after cementing, a wellbore with a smaller inner diameter is formed. Water injection is a commonly used oil displacement method in oilfield development. By injecting water into the formation through a water injection string, formation energy can be replenished, displacing crude oil and flowing into the production wellbore, thereby improving the oilfield's recovery rate.

[0003] The water injection string, from top to bottom, includes tubing, packer, distributor, release safety connector, and hydraulic anchor. Water is injected into the tubing from the surface and distributed to each oil layer via the distributor, which controls the water injection volume for each layer, achieving stratified water injection. In the event of a downhole fault, the shear pins or pins in the release safety connector are cut by raising the tubing string, applying specific torque, or dropping a ball to apply pressure, causing the upper and lower tubing strings to separate and release. After release, the upper tubing string can be retrieved, and then a retrieval tool can be lowered to handle the lower tubing string, reducing the complexity of downhole accident handling.

[0004] Because small-diameter water injection wells use ф60mm tubing in whole or in part, which has poor tensile and torsional strength, there is a risk of the ball seat being sealed or encountering obstruction midway if the ball is dropped and the pressure is lost.

[0005] Chinese patent application CN202321151764.1 discloses a hydraulic release safety connector, comprising an upper connector, a lower connector, a sliding sleeve, a ball, and locking blocks. The lower connector is sealed and fitted onto the lower end of the upper connector. The upper connector has an inlay hole penetrating the side wall and an annular shoulder at its lower end. The locking blocks are respectively inlaid in the inlay hole. The inner side of the lower connector has a locking groove corresponding to the inlay hole. The sliding sleeve is inlaid in the combined inner hole formed by the upper and lower connectors and has a variable diameter shoulder in the middle. The lower shear pin connects to the limiting sleeve, and the upper part has an indented annular groove. The ball can seal the central shaft hole of the sliding sleeve, and pressing cuts the shear pin to release the device. This tool has a complex structure, and the fit between the components requires high precision. It requires the ball to seal the central shaft hole of the sliding sleeve. However, the water injection well injects produced wastewater from the oil field, and the complex wellbore environment and liquid properties lead to severe corrosion and scaling. When the tubing string cannot be successfully unstuck, the ball dropped into the wellhead may not reach the sealing position or may not seal properly. Pressure testing may not generate effective shear force, making it impossible to successfully release the ball.

[0006] Chinese patent application number 202210238086.6 discloses a release tool. The first assembly includes an upper connector, a first connecting sleeve, a piston rod, a piston, a support claw, and a limiting mandrel. The second assembly includes a second connecting sleeve and a main tube. The second connecting sleeve is coaxial and spaced outside the support claw, with one end connected to the first connecting sleeve and the other end threaded to a first retaining sleeve. One end of the main tube extends into the second connecting sleeve and is threaded to the support claw in the opposite direction. When one end of the limiting mandrel slides out of the second shaft hole, the support claw can disengage from the main tube, achieving hydraulic release. Rotating the first assembly forward via the upper connector unlocks the threaded connection between the support claw and the main tube, achieving mechanical release. The drawbacks of this tool are: 1. In water injection wells, it is difficult for the ball to reach the sealing position or the seal is not tight. 2. Hydraulic release requires high pressure. Small-diameter well tubing has limited pressure resistance; excessive pressure may cause the downhole tubing to rupture, leading to serious downhole accidents and increasing operational risks. 3. Mechanical release requires clockwise rotation of the tubing string, and the torsional resistance of tubing in small wells is limited. 4. Hydraulic release requires higher pressure, and there is a risk of the downhole tubing bursting due to corrosion. Utility Model Content

[0007] The purpose of this section is to outline some aspects of embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, and such simplifications or omissions should not be construed as limiting the scope of the present invention.

[0008] In view of the problems existing in the above and / or prior art, this utility model is proposed.

[0009] The purpose of this invention is to provide a soluble release safety connector for small wellbore, which can ensure smooth release, allowing the upper tubing to be pulled out before retrieving the lower tubing, thus greatly reducing the risk of major overhauls.

[0010] To solve the above technical problems, this utility model provides a soluble safety connector for small wellbore applications, comprising:

[0011] The upper connector has symmetrically arranged downward-opening grooves on its outer wall of the middle section;

[0012] The lower connector has its upper part fitted onto the lower outer periphery of the upper connector and fixedly connected to the upper connector by shear pins. Symmetrical tenons are provided on the upper end, and each tenon is embedded in the groove of the upper connector.

[0013] A sealing bushing, the upper end of which has an external threaded section, is connected to the lower end of the internal thread of the upper connector. The lower outer wall of the upper external threaded section is sealed to the lower inner wall of the upper connector. The lower end of the sealing bushing is enlarged to form an outer step and is sealed to the lower inner wall of the lower connector.

[0014] The soluble wristband is located in the annular space between the inner wall of the lower connector and the outer wall of the sealing bushing. Its upper inner circumferential wall abuts against the outer circumferential wall of the middle part of the sealing bushing. There is a gap between the inner wall below the upper inner step and the outer wall of the middle section of the sealing bushing, and it is flush with the lower inner wall of the lower connector. The external thread of the lower outer circumference of the soluble wristband is connected to the internal thread above the inner step of the lower connector.

[0015] As an improvement of this utility model, the top of the soluble wristband abuts against the bottom of the upper connector, and the bottom of the soluble wristband abuts against the inner step of the lower connector.

[0016] As a further improvement of this utility model, the top of the sealing bushing abuts against the inner step of the upper connector, and the sealing bushing is flush with the inner wall of the upper connector.

[0017] As a further improvement of this utility model, two O-rings are embedded in the lower outer periphery of the upper connector to achieve a seal with the upper inner wall of the lower connector.

[0018] As a further improvement of this utility model, multiple shear pins are evenly distributed along the upper circumference of the lower connector.

[0019] As a further improvement of this utility model, the shoulder of the lower end of the tenon of the lower connector abuts against the lower part of the outer step of the upper connector.

[0020] As a further improvement of this utility model, the area below the external thread section at the upper end of the sealing bushing is the upper sealing section of the sealing bushing, and the outer wall of the upper sealing section of the sealing bushing is fitted with two upper sealing rings that seal with the lower inner wall of the upper connector.

[0021] As a further improvement of this utility model, the lower end expansion section of the sealing bushing is the lower sealing section of the sealing bushing, and two lower sealing rings are embedded in the outer periphery of the lower sealing section of the sealing bushing to achieve a seal with the lower inner wall of the lower connector.

[0022] Compared with the prior art, the present invention has achieved the following beneficial effects: 1. The soluble safety joint can be used as a water injection channel and can withstand water injection pressure and a certain axial load;

[0023] 2. When the tubing string gets stuck and the release mechanism fails to work, the shear pin is cut off by lifting the tubing string, which causes the upper connector and sealing bushing to move upward together. The soluble release ring comes into contact with the well fluid and will gradually dissolve under the immersion of the high-salinity well fluid, thus achieving reliable release.

[0024] 3. Ensure that the upper tubing string can be retrieved before the lower tubing string can be retrieved, reducing the risk of major repairs, saving operating costs, and shortening the well occupation period. Attached Figure Description

[0025] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. The drawings are provided for reference and illustration only and are not intended to limit this utility model. Wherein:

[0026] Figure 1 This is a schematic diagram of the structure of the small-bore soluble safety connector of this utility model;

[0027] In the diagram: 1. Upper connector; 2. Shear pin; 3. O-ring; 4. Disposable wristband; 5. Sealing bushing; 5a. Upper sealing ring of bushing; 5b. Lower sealing ring of bushing; 6. Lower connector; 6a. Tenon. Detailed Implementation

[0028] In the following description of this utility model, the terms "upper", "lower", "front", "rear", "left", "right", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and do not mean that the device must have a specific orientation.

[0029] To make the technical means, creative features, achieved objectives and effects of this utility model easier to understand, the present utility model will be further described below with reference to specific illustrations. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments.

[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0031] like Figure 1 As shown, the small-diameter soluble hand-release safety connector of this utility model includes an upper connector 1, a shear pin 2, an O-ring 3, a soluble hand-release ring 4, a sealing bushing 5, and a lower connector 6. The middle section of the outer wall of the upper connector 1 is symmetrically provided with downward-opening grooves. The upper part of the lower connector 6 is fitted onto the lower outer periphery of the upper connector 1, and the upper end is symmetrically provided with upward-extending tenons 6a. Each tenon 6a is embedded in the groove of the upper connector 1 and matches with each other to transmit torque.

[0032] The shoulder of the lower end of the tenon 6a of the lower connector 6 abuts against the lower outer step of the upper connector 1. The upper circumference of the lower connector 6 is fixedly connected to the upper connector 1 by a shear pin 2. Two O-rings 3 are embedded in the lower outer circumference of the upper connector 1 to achieve a seal with the upper inner wall of the lower connector 6.

[0033] The upper external thread of the sealing bushing 5 is connected to the lower internal thread of the upper connector 1. Below the upper external thread of the sealing bushing 5 is the upper sealing section of the sealing bushing. Two upper sealing rings are embedded in the outer wall of the upper sealing section of the sealing bushing to achieve a seal with the lower inner wall of the upper connector 1. The top of the sealing bushing 5 abuts against the lower inner step of the upper connector 1, and the sealing bushing 5 is flush with the inner wall of the upper connector 1.

[0034] The lower end of the sealing bushing 5 extends downward and is provided with a lower sealing section. The lower sealing section expands outward to form an outer step. Two lower sealing rings are embedded in the outer periphery of the lower sealing section and seal with the lower inner wall of the lower connector 6.

[0035] The upper connector 1 and the sealing bushing 5 are made of high-strength materials to ensure stability and reliability under high pressure or large axial load.

[0036] The soluble hand ring 4 is located in the annular space between the inner wall of the lower connector 6 and the outer wall of the sealing bushing 5. The top of the soluble hand ring 4 abuts against the bottom of the upper connector 1. The upper inner wall of the soluble hand ring 4 is a reduced-diameter section, and the inner circumferential wall of the reduced-diameter section abuts against the outer circumferential wall of the middle section of the sealing bushing 5. An inner step is formed below the reduced-diameter section. The inner wall of the soluble hand ring 4 below the inner step is flush with the lower inner wall of the lower connector 6, and a gap is left between it and the outer wall of the middle section of the sealing bushing 5 to form an annular sealed cavity. The bottom of the soluble hand ring 4 abuts against the inner step of the lower connector 6, and the external thread of the lower outer circumference of the soluble hand ring 4 is connected to the internal thread of the lower connector 6.

[0037] When the tubing string becomes stuck and unsuccessful in its movement, the shear pin 2 can be cut by lifting the tubing string under a certain load. This causes the upper connector 1 and the sealing bushing 5 to move upward together. After the lower outer step of the sealing bushing 5 contacts the upper inner step of the soluble release ring 4, if the unsuccessful movement is still not achieved, the unsuccessful movement can continue. At the same time, the lower sealing section of the sealing bushing 5 reaches the upper middle part of the soluble release ring 4, so that the lower inner wall of the soluble release ring 4 contacts the well fluid. The soluble release ring 4 will gradually dissolve under the immersion of the high-salinity well fluid, thereby allowing the upper tubing string to be lifted out and the lower tubing string to be retrieved, greatly reducing the risk of major workovers.

[0038] The above description is merely a preferred embodiment of the present utility model, showing and describing the basic principles, main features, and advantages of the present utility model. It is not intended to limit the scope of patent protection of the present utility model. Those skilled in the art should understand that the present utility model is not limited to the above embodiments. In addition to the above embodiments, the present utility model may have other implementations without departing from the spirit and scope of the present utility model. Various changes and improvements to the present utility model are also possible. All technical solutions formed by equivalent substitutions or equivalent transformations fall within the scope of protection claimed by the present utility model. The scope of protection claimed by the present utility model is defined by the appended claims and their equivalents. Technical features not described in the present utility model can be implemented by or using existing technology, and will not be elaborated here.

Claims

1. A soluble safety connector for small-diameter wells, characterized in that, include: The upper connector (1) has symmetrically arranged downward-opening grooves on the outer wall of its middle section; The lower connector (6) is fitted onto the lower outer periphery of the upper connector (1) and is fixedly connected to the upper connector (1) by a shear pin (2). Symmetrical tenons are provided at the upper end, and each tenon is embedded in the groove of the upper connector (1). The sealing bushing (5) has an external thread section at its upper end connected to the internal thread at the lower end of the upper connector (1). The lower outer wall of the external thread section at its upper end is sealed to the lower inner wall of the upper connector (1). The lower end of the sealing bushing (5) is enlarged to form an outer step and is sealed to the lower inner wall of the lower connector (6). The soluble wristband (4) is located in the annular space between the inner wall of the middle part of the lower connector (6) and the outer wall of the sealing bushing (5). Its upper inner peripheral wall abuts against the middle outer peripheral wall of the sealing bushing (5). The inner wall below the upper inner step of the wristband (4) leaves a gap with the middle outer wall of the sealing bushing (5) and is flush with the lower inner wall of the lower connector (6). The external thread of the lower outer periphery of the soluble wristband (4) is connected to the internal thread above the inner step of the lower connector (6).

2. The small-bore soluble safety connector according to claim 1, characterized in that: The top of the soluble wristband (4) abuts against the bottom of the upper connector (1), and the bottom of the soluble wristband (4) abuts against the inner step of the lower connector (6).

3. The small-bore soluble safety connector according to claim 1, characterized in that: The top of the sealing bushing (5) abuts against the inner step of the upper connector (1), and the sealing bushing (5) is flush with the inner wall of the upper connector (1).

4. The small-bore soluble safety connector according to claim 1, characterized in that: The lower outer periphery of the upper connector (1) is fitted with two O-rings (3) to achieve a seal with the upper inner wall of the lower connector (6).

5. The small-bore soluble safety connector according to claim 1, characterized in that, The shear pins (2) are evenly distributed along the upper circumference of the lower connector (6).

6. The small-bore soluble safety connector according to claim 1, characterized in that, The shoulder of the lower end of the tenon of the lower connector (6) abuts against the lower step of the upper connector (1).

7. The small-bore soluble safety connector according to claim 1, characterized in that, Below the external thread section at the upper end of the sealing bushing (5) is the upper sealing section of the sealing bushing. The outer wall of the upper sealing section of the sealing bushing is fitted with two upper sealing rings (5a) that seal the lower inner wall of the upper connector (1).

8. The small-bore soluble safety connector according to claim 1, characterized in that, The lower end of the sealing bushing (5) is an enlarged section, which is the lower sealing section of the sealing bushing. Two lower sealing rings (5b) are embedded on the outer periphery of the lower sealing section of the sealing bushing and seal the lower inner wall of the lower connector (6).

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