Novel plunger suitable for inner coating oil pipe

Abstract

The invention discloses a novel plunger suitable for an inner coating oil pipe, and belongs to the technical field of oil gas production in the petroleum industry, the novel plunger suitable for the inner coating oil pipe comprises a plunger body which extends along an axis O and is made of a hard metal material; and the shell component at least covers the radial outer side of part of the plunger body and is made of a non-metal material, and part of the outer surface of the shell component forms a contact surface with the inner wall of the oil pipe. The radial outer side of the plunger body made of the hard metal material is coated with the shell part made of the non-metal material, and part of the outer surface of the shell part serves as the contact surface of the inner wall of the oil pipe, so that scratches of the plunger to the inner wall of the oil pipe in the using process can be reduced, and the service life of the oil pipe is prolonged.

Description

Technical Field

[0001] The invention belongs to the technical field of oil and gas production in the petroleum industry, and in particular relates to a novel plunger suitable for an inner coating oil pipe. Background Art

[0002] my country has very rich shale gas resources, and its recoverable reserves rank among the highest in the world. my country has become another major region in the world to achieve large-scale development of shale gas, and is the largest shale gas producer outside North America. Driven by consumer demand, my country's natural gas production will continue to grow rapidly, and shale gas resources have great potential. However, due to the complex geological conditions in domestic shale gas storage areas, exploration and development face many difficulties. In particular, as the time of shale gas extraction increases, low-pressure and low-yield wells gradually increase, formation energy becomes lower and lower, and wellbore liquid accumulation occurs frequently, seriously restricting the release of gas well production capacity. Shale gas reservoirs are artificial gas reservoirs formed by the combination of "horizontal wells + staged volume fracturing". Shale gas wells have a fast decline in the early stage and the output fluid is pressure-sensitive. Fracture flowback fluid and flowback last throughout the entire production period. The production time is long during the low-production period, and the timing of process intervention needs to be earlier. A large amount of excess EUR in the low-production period needs to be produced by drainage technology; shale gas pipe corrosion and wellbore liquid accumulation are common problems that affect the normal production of shale gas wells. Carbon dioxide, sulfate-reducing bacteria and iron bacteria corrosion are the main causes of shale gas well pipe corrosion, which can easily cause pipe perforation, pipe breakage and other adverse conditions, seriously affecting the normal production of gas wells; in response to the problem of downhole pipe corrosion, the main method of inner coating pipe anti-corrosion is to ensure the normal production of gas wells. The inner coating anti-corrosion process can effectively prevent corrosion by adding a pipe wall covering layer to isolate the gas medium. It is currently used in various shale gas companies and has achieved certain results.

[0003] With the development of shale gas fields, the formation energy decreases, the gas production of gas wells gradually falls below the critical liquid-carrying flow rate, the gas cannot bring the liquid in the wellbore to the ground, liquid accumulates gradually at the bottom of the well and in the wellbore, and eventually the gas-producing layer is completely crushed, resulting in the inability of the gas well to produce normally; the plunger lifting process is currently the preferred plunger process technology for shale gas and gas well drainage and stable production, with the characteristics of low cost, low failure rate, economy and environmental protection, unmanned operation, remote transmission and remote control; however, the coated tubing and plunger process have poor adaptability, mainly because conventional plungers are mostly made of hard metals such as carbon steel and nickel-plated alloy steel, and there are collisions and frictions between the tubing end faces and the wall during the plunger cycle operation. Early metal plunger experiments found that the tubing end face coatings were all collided and fell off, and the wall coatings also had obvious damage. The risk of metal plungers wearing the wall of the coated tubing and causing coating failure is relatively high, which can easily cause large-scale shedding of the coating at the tubing coupling and multiple scratches on the main body coating, greatly shortening the service life of the coated tubing. Summary of the invention

[0004] The purpose of the present invention is to provide a new type of plunger suitable for inner coating oil pipes to solve the problems of the plunger in the use process mentioned in the above background technology.

[0005] To achieve the above object, the present invention provides the following technical solution: a new type of plunger suitable for inner coating oil pipe, comprising:

[0006] A plunger body extending along the axis O and made of a hard metal material;

[0007] The shell component at least covers a portion of the radially outer side of the plunger body and is made of a non-metallic material. A portion of the outer surface of the shell component serves as a contact surface with the inner wall of the oil pipe.

[0008] Preferably, the plunger body is made of carbon steel and nickel-plated alloy steel.

[0009] Preferably, the housing component is made of engineering plastic.

[0010] Preferably, the plunger body includes a cylindrical main body and an end body arranged at one axial end of the main body, the outer diameter of the end body is larger than the outer diameter of the main body, and a salvage structure is provided at one axial end of the end body away from the main body.

[0011] Preferably, the shell component includes a first portion covering the radially outer side of the main body portion and a second portion covering the radially outer side of the end body portion, and the outer diameter of the first portion is the same as the outer diameter of the second portion.

[0012] Preferably, at least one annular groove is formed on the outer surface of the first part, and the shell component is formed with an opening at the position of the annular groove.

[0013] Preferably, the novel plunger further comprises at least one set of rolling components, wherein a single set of rolling components comprises a plurality of rolling structures spaced apart in the radial direction, wherein the rolling structures comprise:

[0014] A channel is provided on the side wall of the shell component and extends in a radial direction;

[0015] A ball component is arranged in the channel, and the ball component is configured to contact and roll with the inner wall of the oil pipe during the operation of the novel plunger.

[0016] Preferably, the rolling structure further comprises:

[0017] an elastic member configured to apply a radially outward force to the ball member;

[0018] The limiting component is arranged on the outer side of the ball component, is configured to limit the ball component, and is formed with an opening for part of the ball component to pass through.

[0019] Preferably, the elastic component is a spring, and the spring is configured to be compressed.

[0020] Preferably, the limiting component has an arc surface matched with the ball component.

[0021] Preferably, the rolling assemblies are provided in two groups and are respectively located at two axial ends of the shell component.

[0022] Preferably, the salvage structure comprises:

[0023] A neck portion, which is a cylindrical member extending along the axis O, wherein the diameter of the neck portion is smaller than the diameter of the housing member;

[0024] The end cover is connected to one axial end of the neck body, and the diameter of the end cover is larger than the diameter of the neck body and smaller than the diameter of the shell component.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] The present application covers a shell component made of non-metallic material on the radial outer side of a plunger body made of hard metal material, and uses part of the outer surface of the shell component as the contact surface of the inner wall of the oil pipe, thereby reducing the scratches on the inner wall of the oil pipe caused by the plunger during use and improving the service life of the oil pipe. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of the overall structure of the present invention.

[0028] Figure 2 The present invention Figure 1 Schematic diagram of some locations.

[0029] Figure 3 The present invention Figure 2 Schematic diagram of some locations.

[0030] Figure 4 The rolling structure of the present invention is shown in FIG. Figure 1 .

[0031] Figure 5 The rolling structure of the present invention is shown in FIG. Figure 2 .

[0032] In the figure:

[0033] 100, plunger body; 101, main body; 102, end body;

[0034] 200, housing component; 201, first part; 202, second part; 203, annular groove body;

[0035] 300, rolling structure; 301, channel; 302, ball component; 303, limiting component; 304, elastic component;

[0036] 400, salvage structure; 401, neck body; 402, end cover. DETAILED DESCRIPTION

[0037] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0038] Reference Figure 1 A new type of plunger suitable for inner coating oil pipe (hereinafter referred to as the new type of plunger), the main body of which is composed of a plunger body 100 and a shell component 200, wherein the plunger body 100 is roughly a columnar component extending along the axis O, and a salvage structure 400 is formed at one axial end of the plunger body 100, and based on the design of the salvage structure 400 (detailed description will be given later), the salvage operation of the new type of plunger can be realized under special circumstances to remove the new type of plunger as a whole from the wellbore;

[0039] Reference Figure 1 , 2 and 3, the plunger body 100 comprises a main body 101 and an end body 102, wherein the main body 101 is constituted as a cylindrical component extending along the axis O, the end body 102 is formed at one end of the main body 101 in the axial direction and is connected to the salvage structure 400, and the end body 102 has a portion extending radially outward, that is, the outer diameter of the end body 102 is greater than the outer diameter of the main body 101, and correspondingly, the shell component 200 comprises a first portion 201 coated on the outer circumferential surface of the main body 101 and a second portion 202 coated on the outer circumferential surface of the end body 102, wherein the first portion 201 is roughly constituted as a cylindrical component, and the second portion 202 is formed by a portion of the first portion 201 extending along the circumferential surface of the end body 102. The axis O is extended to form, and the outer diameters of the first part 201 and the second part 202 are the same. Further, the plunger body 100 is made of metal material, that is, the main body 101 and the end body 102 are both made of metal material, so as to increase the overall weight of the new plunger, and ensure that the new plunger can overcome the resistance and fall to the downhole stopper position when in use, that is, the plunger body 100 is used as the gravity carrier of the new plunger to drive the shell component 200 to fall. In some embodiments, the plunger body 100 is made of hard metal. For example, the main body 101 can be made of carbon steel, nickel-plated alloy steel and other materials to improve the strength of the main body 101 under the premise of ensuring the weight.

[0040] Reference Figure 1 , 23. At least part of the outer surface of the shell component 200 is formed as a surface that contacts the inner wall of the oil pipe during the use of the new plunger, that is, during the use of the new plunger, at least part of the outer surface of the shell component 200 and the inner wall of the oil pipe rub against each other. In some embodiments, the shell component 200 is made of non-metallic material to reduce the scratching of the inner coating of the oil pipe by the contact of the new plunger with the inner wall of the oil pipe during the movement. For example, the shell component 200 is made of engineering plastics. Engineering plastics have excellent comprehensive properties, such as high rigidity, small creep, high mechanical strength, good heat resistance, and good electrical insulation. They can be used for a long time in harsh chemical and physical environments and can replace metals as engineering structural materials. In a preferred embodiment of the shell component 200, PEEK material is selected as the material of the shell component 200. PEEK material is a special engineering plastic with excellent properties such as high temperature resistance, self-lubrication, easy processing and high mechanical strength. The shell component 200 made of this material can reduce the scratching of the inner wall of the oil pipe while ensuring its own strength to increase the service life.

[0041] Back to Figure 3 At least one annular groove 203 is provided on the first part 201 of the shell component 200. When a plurality of annular grooves 203 are provided, the plurality of annular grooves 203 are arranged at equal intervals along the axis O direction to form a shell component 200 that is roughly in the shape of a "fish skeleton". Correspondingly, based on the at least one annular groove 203 provided on the circumferential outer surface of the first part 201 of the shell component 200, the circumferential outer surface of the first part 201 of the shell component 200 is divided into an opening part (i.e., the position of the annular groove 203) and a contact part (a non-annular groove 203 position). When the novel plunger moves inside the oil pipe, the contact part of the shell component 200 contacts the inner wall of the oil pipe and forms a boundary seal to ensure that the liquid can be lifted normally. The opening part of the shell component 200 is separated from the inner wall of the oil pipe to reduce the contact area between the first part 201 and the inner wall of the oil pipe, thereby reducing the resistance of the novel plunger during movement and reducing the friction between the shell component 200 and the inner wall of the oil pipe.

[0042] In some embodiments, referring to FIGS. 1, 4 and 5, the novel plunger further comprises at least one group of rolling assemblies. When there are multiple groups of rolling assemblies, the multiple groups of rolling assemblies are arranged at equal intervals along the axial direction O. In a preferred embodiment, there are two groups of rolling assemblies, which are respectively located at the two axial ends of the first part 201 of the shell component 200. Based on the rolling assemblies arranged at the two axial ends of the first part 201 of the shell component 200, the shell component 200 and the inner wall of the oil pipe can be changed from sliding contact to rolling contact at this position, thereby reducing the resistance of the novel plunger during operation and reducing the starting pressure of the plunger during the upward process.

[0043] In some embodiments, reference Figure 4 , a single rolling assembly is composed of a plurality of rolling structures 300 arranged at intervals in the circumferential direction. In some embodiments, a single rolling assembly is composed of an even number of rolling structures 300. For example, Figure 4 The rolling assembly consisting of six rolling structures 300 is exemplarily shown, that is, adjacent rolling structures 300 are arranged at an angle of 60°. Figure 4 and 5 The rolling structure 300 includes a channel 301 opened in the radial direction, that is, the channel 301 extends in the radial direction. In some embodiments, the channel 301 penetrates the side wall of the housing component 200 in the radial direction, and the channel 301 is configured as a cylindrical channel 301, that is, the cross section of the channel 301 is circular. Figure 4 and 5 The rolling structure 300 further includes a ball component 302, which is configured to contact and roll with the inner wall of the oil pipe when the new plunger moves in the oil pipe. In some embodiments, the ball component 302 is made of a non-metallic material, for example, the same PEEK material as the housing component 200 is used to prevent the ball component 302 from scratching the coating on the inner wall of the oil pipe during rolling; Return to Figure 4 and 5The rolling structure 300 further includes an elastic component 304 and a limiting component 303, wherein the elastic component 304 is configured to apply a radially outward force to the ball component 302 so that part of the ball component 302 keeps in contact with the inner wall of the oil pipe and rolls during use of the new plunger. The limiting component 303 is arranged at one end of the radially outer side of the channel 301, and is used to limit the position of the ball component 302 on the radial outer side. In some embodiments, the elastic component 304 is a spring, and the spring is configured to be compressed, that is, the spring is in a compressed state, and the restoring force of the spring is used as the radially outward force applied to the ball component 302. At the same time, when the channel 301 penetrates the inner wall of the shell component 200 in the radial direction, one end of the spring is fixed to the outer circumferential surface of the body component. In a preferred embodiment, the cross-sectional specifications of the ball component 302 and the channel 301 are adapted to prevent the ball component 302 from rolling. The movement occurs in the radial direction of the channel 301. In some embodiments, the above-mentioned limiting component 303 is formed on the inner wall of the channel 301 and extends inwardly along the radial direction of the channel 301, and an opening is formed in the middle of the limiting component 303, which allows part of the ball component 302 to pass through and contact the inner wall of the oil pipe. At the same time, an arc surface is formed on the limiting component 303, and the arc surface is adapted to the surface of the ball component 302. During the operation of the new plunger, the ball component 302 is subjected to a radial outward force from the spring. Under the action of this force, part of the ball component 302 passes through the opening of the limiting component 303, and part of the surface of the ball component 302 contacts the arc surface of the limiting component 303. At the same time, the part of the ball component 302 that passes through the opening position of the limiting component 303 contacts the inner wall of the oil pipe, and causes the ball component 302 to roll during the operation of the new plunger;

[0044] Reference Figure 2 The salvage structure 400 includes a neck portion 401 and an end cover portion 402, wherein the neck portion 401 is configured as a cylindrical component extending along the axis O, one axial end of the neck portion 401 is connected to one axial end of the end body portion 102 of the plunger body 100, and the other axial end of the neck portion 401 is connected to the end cover portion 402 of the salvage structure 400, that is, the neck portion 401 is configured as a connecting component between the end cover portion 402 and the plunger body 100, and the diameter of the neck portion 401 is smaller than the diameters of the end cover portion 402 and the end body portion 102. Further, the diameter of the end cover portion 402 is larger than the diameter of the neck portion 401 and smaller than the diameter of the shell component 200.

[0045] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A new type of plunger suitable for inner coating oil pipe, characterized by: include: A plunger body extending along the axis O and made of a hard metal material; The shell component at least covers a portion of the radially outer side of the plunger body and is made of a non-metallic material. A portion of the outer surface of the shell component serves as a contact surface with the inner wall of the oil pipe.

2. A new type of plunger suitable for inner coating oil pipe according to claim 1, characterized in that: The plunger body is made of carbon steel and nickel-plated alloy steel materials.

3. A new type of plunger suitable for inner coating oil pipe according to claim 1 or 2, characterized in that: The housing component is made of engineering plastic.

4. A new type of plunger suitable for inner coating oil pipe according to claim 1, characterized in that: The plunger body comprises a cylindrical main body and an end body arranged at one axial end of the main body, the outer diameter of the end body is larger than the outer diameter of the main body, and a salvage structure is provided at one axial end of the end body away from the main body.

5. A new type of plunger suitable for inner coating oil pipe according to claim 4, characterized in that: The shell component includes a first portion covering the radially outer side of the main body portion and a second portion covering the radially outer side of the end body portion, and the outer diameter of the first portion is the same as the outer diameter of the second portion.

6. A new type of plunger suitable for inner coating oil pipe according to claim 5, characterized in that: The outer surface of the first part is provided with at least one annular groove, and the shell component is provided with an opening at the position of the annular groove.

7. A new type of plunger suitable for inner coating oil pipe according to claim 1 or 4, characterized in that: The novel plunger further comprises at least one set of rolling components, wherein a single set of rolling components comprises a plurality of rolling structures spaced apart in the radial direction, wherein the rolling structures comprise: A channel is provided on the side wall of the shell component and extends in a radial direction; A ball component is arranged in the channel, and the ball component is configured to contact and roll with the inner wall of the oil pipe during the operation of the novel plunger.

8. A new type of plunger suitable for inner coating oil pipe according to claim 7, characterized in that: The rolling structure also includes: an elastic member configured to apply a radially outward force to the ball member; The limiting component is arranged on the outer side of the ball component, is configured to limit the ball component, and is formed with an opening for part of the ball component to pass through.

9. A new type of plunger suitable for inner coating oil pipe according to claim 8, characterized in that: The elastic member is a spring, and the spring is configured to be compressed.

10. A new type of plunger suitable for inner coating oil pipe according to claim 8 or 9, characterized in that: The limiting component has an arc surface matched with the ball component.

11. A new type of plunger suitable for inner coating oil pipe according to claim 7, characterized in that: The rolling components are provided in two groups and are respectively located at two ends of the axial direction of the shell component.

12. A new type of plunger suitable for inner coating oil pipe according to claim 4, characterized in that: The salvage structure comprises: A neck portion, which is a cylindrical member extending along the axis O, wherein the diameter of the neck portion is smaller than the diameter of the housing member; The end cover is connected to one axial end of the neck body, and the diameter of the end cover is larger than the diameter of the neck body and smaller than the diameter of the shell component.

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