Sleeve scraper

Abstract

The invention belongs to the technical field of oil-gas exploration and development or geological drilling, and discloses a casing scraper through which the inner wall of a casing can be cleaned. The casing scraper comprises a knife cage, an elastic piece, a limiting pin and an isolating layer, the cutter cage can be connected with an external drill rod through a penetrating center shaft, so that the cutter cage is conveyed to a designated position of an underground casing pipe for cleaning through the drill rod, a groove is formed in the circumferential face of the cutter cage, one end of the elastic piece is connected into the groove, the other end of the elastic piece is connected with a scraper, and the elastic piece enables the scraper to keep the trend of extending out of the groove. The limiting pin penetrates through the scraper, at least one end of the limiting pin penetrates into the knife cage so that the scraper can be limited to extend out of the groove, and the limiting pin is made of a soluble metal material so that the limiting pin can be dissolved by water or drilling fluid; the scraper can be started for scraping in a specified well section, so that movable parts such as a piston are reduced, and the service life is prolonged.

Description

Technical Field

[0001] The present invention relates to the technical field of oil and gas exploration and development or geological drilling operations, and particularly relates to a casing scraper. Background Art

[0002] During the drilling, completion, and workover processes of oil and gas wells, it is necessary to thoroughly clean the inner wall of the casing, remove residual cement stone, mud cake, debris and other obstacles, and form a smooth wellbore environment to prepare for subsequent production increase and running tools. The casing scraper is a commonly used wellbore cleaning tool that can clean the dirt and attachments on the inner wall of the casing by scraping. The casing scraper is often used in combination with tools such as milling cones. During plug drilling and milling operations, it is usually required that the scraping tool remains closed and the scraping blade does not contact the wellbore wall to prevent the hard scraping blade from rotating and scratching the inner wall of the casing. After plug drilling is completed, when the drill bit reaches a specific depth, the scraping tool needs to be opened to repeatedly scrape a specific position at the bottom of the well to ensure the smooth operation and effective setting of subsequent completion tools.

[0003] Currently, the casing scrapers used in well sites are mainly of two types. One is the spring type, where the scraping blade is in an open state on the ground and continuously scrapes the wellbore wall after entering the well, and the working distance almost covers the entire length of the wellbore. During deep well operations, the scraping blade is prone to premature failure, affecting the cleaning effect of key parts at the bottom of the well. The other type of casing scraper is the hydraulic type, where the scraping blade is controlled by a set of piston mechanisms. Generally, a ball is dropped from the ground, and after a high-pressure chamber is established inside the casing scraper, the scraping blade is opened and then continuously scrapes the wellbore wall. This type of casing scraper adds piston mechanisms, ball-catching mechanisms, etc., reducing the overall strength of the tool and making it difficult to meet the performance requirements such as high torsional resistance and high tensile resistance during operations in deep wells below 8000 meters and ultra-deep wells. Summary of the Invention

[0004] The purpose of the present invention is to provide a casing scraper that reduces movable parts such as pistons, improves the strength of the tool, can meet the operation requirements of deep wells and ultra-deep wells, can open the scraping blade at a specific position underground, and extends the service life.

[0005] To achieve this purpose, the present invention adopts the following technical solutions:

[0006] A casing scraper for cleaning the inner wall of the casing, comprising:

[0007] A cutter cage, on the peripheral surface of which there are grooves;

[0008] An elastic member, one end of which is connected in the groove, and the other end of which is connected with a scraping blade, and the elastic member makes the scraping blade tend to extend out of the groove;

[0009] A limiting pin that penetrates the scraping blade, and at least one end of the limiting pin extends deep into the cutter cage to limit the scraping blade from protruding out of the groove. The limiting pin is made of a soluble metal material so that it can be dissolved by water or drilling fluid;

[0010] An isolation layer is provided on the limiting pin to isolate the limiting pin from the external environment. The isolation layer is made of a phase change material.

[0011] Preferably, a plurality of groups of the grooves are arranged along the axial direction of the cutter cage. Multiple grooves in the same group are located on the same outer diameter of the cutter cage, and multiple grooves in different groups are staggered along the axial direction of the cutter cage.

[0012] Preferably, the projection set of the scraping blades in the groove along the axial direction of the cutter cage covers the inner wall of the casing.

[0013] Preferably, a first hole is provided on one side wall of the groove, and a second hole opposite to it is provided on the other side wall. The first hole and / or the second hole penetrate the surface of the cutter cage. A third hole is provided through the scraping blade, and the limiting pin passes through the third hole and its end is located in the first hole and the second hole.

[0014] Preferably, a sealing ring is provided in the first hole and / or the second hole.

[0015] Preferably, the isolation layer includes a first isolation layer and a second isolation layer. The first isolation layer is provided between the scraping blade and the side wall of the groove and surrounds the limiting pin; the second isolation layer seals the first hole and / or the second hole.

[0016] Preferably, a limiting ring is provided on the bottom wall of the groove, and the elastic member is sleeved outside the limiting ring.

[0017] Preferably, the phase change temperature of the isolation layer is 180°C - 200°C.

[0018] Preferably, the scraping blade includes a blade body and a scale. The blade body is connected to the elastic member. An installation hole is provided on the side of the blade body facing away from the elastic member, and the scale is arranged in the installation hole. The scale is divided into multiple wear identification segments along its length direction.

[0019] Preferably, the colors of the multiple wear identification segments are different from each other.

[0020] The beneficial effects of the present invention:

[0021] The scraper is restricted within the groove by an isolation layer made of a phase change material and a limiting pin made of a soluble metal material. Thus, when the casing scraper is lowered into the well, the scraper can be prevented from contacting the inner wall of the casing, protecting the scraper from additional wear. When reaching the designated well section underground, the temperature reaches the phase change temperature point of the phase change material, and the phase change of the phase change material exposes the limiting pin. The limiting pin contacts and dissolves in the water or drilling fluid inside the casing. At this time, the scraper is released from the restriction and extends out of the groove to contact the inner wall of the casing, so as to be able to start scraping at the designated well section. This structure also reduces movable parts such as pistons, improves the overall strength of the tool, and extends the service life. Brief Description of the Drawings

[0022] Figure 1 is a partial sectional view of the casing scraper of the present invention;

[0023] Figure 2 is Figure 1 the enlarged view at position A in

[0024] Figure 3 is a schematic diagram showing the staggered distribution of the grooves and the cutter cage of the present invention;

[0025] Figure 4 is a schematic diagram of the scraper in the casing scraper of the present invention;

[0026] Figure 5 is a schematic diagram showing the scale located inside the cutter body of the casing scraper of the present invention.

[0027] In the figure:

[0028] 1. Cutter cage; 2. Elastic member; 3. Limiting pin; 4. Isolation layer; 41. First isolation layer; 42. Second isolation layer; 5. Groove; 6. Scraper; 61. Cutter body; 62. Scale; 7. Limit ring; 8. Sealing ring; 100. Central axis. Detailed Description of the Preferred Embodiments

[0029] The present invention will be further described in detail below with reference to the drawings and embodiments. It can be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. Additionally, it should be noted that for the sake of description, only the parts related to the present invention are shown in the drawings, rather than all the structures.

[0030] In the description of the present invention, unless otherwise clearly defined and limited, the terms "connected", "connected to", and "fixed" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the internal communication of two components or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0031] In the present invention, unless otherwise clearly specified and defined, the first feature being "on" or "under" the second feature may include the direct contact between the first and second features, or may include the situation where the first and second features are not in direct contact but in contact through additional features therebetween. Moreover, the first feature being "above", "over" and "on top of" the second feature includes that the first feature is directly above and obliquely above the second feature, or merely indicates that the horizontal height of the first feature is higher than that of the second feature. The first feature being "under", "beneath" and "underneath" the second feature includes that the first feature is directly below and obliquely below the second feature, or merely indicates that the horizontal height of the first feature is lower than that of the second feature.

[0032] In the description of this embodiment, the orientation or positional relationships such as "upper", "lower", "left" and "right" are based on the orientation or positional relationships shown in the drawings, and are only for the convenience of description and simplifying the operation, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation to the present invention. In addition, the terms "first" and "second" are only used for distinction in description and have no special meanings.

[0033] As Figures 1 to 5 shown, the present invention provides a casing scraper capable of cleaning the inner wall of the casing through it; the casing scraper includes a cutter cage 1, an elastic member 2, a limiting pin 3 and an isolation layer 4; the cutter cage 1 can be connected to an external drill pipe through a penetrated central shaft 100, and thus be sent to a specified position of the downhole casing through the drill pipe for cleaning. A groove 5 is arranged on the peripheral surface of the cutter cage 1. One end of the elastic member 2 is connected in the groove 5, and the other end of the elastic member 2 is connected with a scraper 6. The elastic member 2 makes the scraper 6 keep a tendency to extend out of the groove 5; the limiting pin 3 penetrates through the scraper 6, and at least one end of the limiting pin 3 extends into the cutter cage 1 to limit the scraper 6 from extending out of the groove 5. The limiting pin 3 is made of a soluble metal material so as to be dissolved by water or drilling fluid; the isolation layer 4 is arranged on the limiting pin 3 to isolate the limiting pin 3 from the external environment, and the isolation layer 4 is made of a phase change material.

[0034] The scraper 6 is limited in the groove 5 by the isolation layer 4 made of a phase change material and the limiting pin 3 made of a soluble metal material. Thus, when the casing scraper goes down the well, the scraper 6 can not contact with the pipe wall of the casing, protecting the scraper 6 from additional wear; and when it reaches the specified well section downhole, the temperature reaches the phase change temperature point of the phase change material, and the phase change of the phase change material exposes the limiting pin 3. The limiting pin 3 contacts with the water or drilling fluid in the casing and dissolves. At this time, the scraper 6 is released from the limitation and extends out of the groove 5 to contact with the pipe wall of the casing, so as to be able to start scraping with the scraper 6 at the specified well section, extending the service life; and this structure reduces movable parts such as pistons, improving the overall strength of the tool and meeting the operation requirements of deep wells and ultra-deep wells of 8000 meters and below.

[0035] Exemplarily, the limiting pin 3 is made of an aluminum-magnesium alloy so that it can be dissolved by water or drilling fluid. It can be understood that the time required for the dissolution of the limiting pin 3 can be controlled by changing the component ratio of the aluminum-magnesium alloy. This is the prior art and will not be elaborated here. For the operation requirements of deep wells and ultra-deep wells of 8000 meters and below, since the geothermal gradient of the oil field is generally 2-3 °C / 100m, the temperature of a general 8000m deep well exceeds 180 °C. Therefore, the phase change point of the phase change material in this embodiment is between 180 °C and 200 °C to ensure that the phase change material undergoes a phase change within the required range. Exemplarily, the phase change material can be paraffin wax. It should be noted here that for different well depths with different requirements, different phase change materials can be selected, and through the phase change points of different phase change materials, different well depths can be adapted.

[0036] In this embodiment, multiple groups of grooves 5 are provided. The number of grooves 5 in each group is multiple. The multiple grooves 5 in different groups are axially arranged and distributed along the cutter cage 1, and the multiple grooves 5 in the same group are located on the same outer diameter of the cutter cage 1, so as to cut in the circumferential direction of the casing. Exemplarily, two groups are arranged axially along the cutter cage 1, and 3-4 grooves 5 are arranged at intervals within the same group. It can be understood that each groove 5 is correspondingly provided with an elastic member 2, a limiting pin 3, a scraping blade 6, and an isolation layer 4. The multiple grooves 5 in different groups are staggered in the circumferential direction of the cutter cage 1, so that the cutting can be made more comprehensive through the above settings. Further, in order to make the cutting cover the entire casing, the projection set of the scraping blades 6 in the grooves 5 along the axial direction of the cutter cage 1 covers the inner wall of the casing, thereby reducing the generation of dead corners and making the cutting effect better.

[0037] Further, the size of the scraping blade 6 is smaller than the size of the groove 5, so as to avoid interference between the scraping blade 6 and the groove wall of the groove 5 during the process of the scraping blade 6 entering and exiting the groove 5, and avoid jamming of the scraping blade 6. In addition, in order to make the entry and exit of the scraping blade 6 more stable, multiple elastic members 2 can be arranged in the groove 5 to make the force on the scraping blade 6 more stable. Furthermore, a limiting ring 7 is provided at the bottom of the groove 5, and the elastic member 2 is sleeved outside the limiting ring 7, so that the elastic member 2 can remain stable in both the compressed and extended states, avoiding excessive deviation of the scraping blade 6; and by setting the height of the limiting ring 7, the depth of the scraping blade 6 entering the groove 5 can be preset, so as to avoid excessive compression of the elastic member 2 by the scraping blade 6 during scraping and avoid failure of the elastic member 2. In this embodiment, the elastic member 2 is a compression spring.

[0038] In this embodiment, a first hole is provided on one of the side walls of the groove 5, and a second hole is provided on the other side wall opposite thereto, wherein at least one of the first hole and the second hole penetrates the surface of the knife cage 1, that is, one of the first hole and the second hole is a through hole, one is a blind hole, or both are through holes, and a through third hole is provided on the scraper 6. When the scraper 6 is located in the groove 5, the first hole, the second hole, and the third hole can be made coaxial, so that the limiting pin 3 can penetrate through the first hole or the second hole penetrating the surface of the knife cage 1, penetrate through the third hole on the scraper 6, and make the limiting pin 3 penetrate into the other of the first hole and the second hole, thereby limiting the scraper 6. This method also facilitates the installation of the limiting pin 3. By way of example, in this embodiment, the first hole is a through hole, and the second hole is a blind hole.

[0039] In order to cooperate with the above-mentioned plug-in form, the isolation layer 4 includes a first isolation layer 41 and a second isolation layer 42. The first isolation layer 41 is arranged between the scraper 6 and the groove 5, and surrounds the limiting pin 3, so that the first isolation layer 41 blocks the portion of the limiting pin 3 exposed between the scraper 6 and the groove 5, thereby isolating it from the external environment; and the first isolation layer 41 can also block the openings of the first hole and the second hole located on the inner side of the groove 5; the second isolation layer 42 blocks the first hole and / or the second hole, thereby blocking the opening of the first hole and / or the second hole set as a through hole away from the groove 5, so that the limiting pin 3 is isolated from the external environment. Furthermore, in order to prevent the limiting pin from falling off from the first hole and / or the second hole that penetrates the surface of the knife cage 1 during the movement process, a blocking ring 8 is arranged in the first hole and / or the second hole, and the blocking ring 8 is provided with an opening to connect to the external environment, and the limiting pin 3 and the second isolation layer 42 are arranged on both sides of the blocking ring 8.

[0040] In this embodiment, abutment plates are provided on the upper and lower sides of the scraper 6, and the abutment plates are provided on the knife cage 1, that is, two abutment plates are provided on both sides of the groove 5 in the axial direction of the knife cage 1, so that when the scraper 6 is ejected from the groove 5 by the elastic member 2, it is restricted by the abutment plates in the axial direction of the knife cage 1, so as to avoid the scraper 6 falling off during the scraping operation of moving up and down.

[0041] In this embodiment, the scraping blade 6 includes a blade body 61 and a scale 62. The blade body 61 is connected to the elastic member 2, and the blade body 61 can be made of 42CrMo material. An installation hole is provided on the side of the blade body 61 facing away from the elastic member 2. The installation hole extends vertically inward from the surface of the blade body 61. The scale 62 is inserted into the installation hole. The scale 62 is divided into multiple wear identification segments along its length direction. Since the scale 62 and the blade body 61 are worn together during the scraping operation, after the scraping is completed, by observing the wear identification segment shown on the exposed end face of the scale 62, the current wear amount of the blade body 61 can be identified, and the subsequent wear amount can be predicted. Thus, the operator can reasonably arrange the replacement time of the scraping blade 6 in cooperation with the operation procedure, ensuring high-quality operation and improving operation efficiency. To ensure the accuracy of measurement, the scale 62 and the depth of the installation hole are kept consistent. In this embodiment, both the installation hole and the scale 62 are cylindrical. To facilitate the insertion of the scale 62, one end of the scale 62 is chamfered. To prevent the scale 62 from falling off the installation hole unexpectedly, the outer peripheral wall of the scale 62 is serrated.

[0042] For more convenient identification, the colors of the multiple wear identification segments are different from each other. Exemplarily, the total thickness of the blade body 61 is 8 mm; the installation hole can be opened to 6 mm; the wear identification segments are set to three segments, which are successively set as a first wear identification segment in blue, a second wear identification segment in yellow, and a third wear identification segment in red from the surface of the blade body 61 to the inside. The first wear identification segment is 2 mm, the second wear identification segment is 1 mm; the third wear identification segment is 3 mm. Exemplarily, the scale 62 can be made of, but not limited to, materials such as aluminum alloy, copper alloy, or plastic.

[0043] After each operation is completed, by observing the color of the scale 62, the general wear law during the operation can be judged, and the subsequent wear amount can be predicted. For example, when a new scraping blade 6 is used for a certain well when it enters the well, the exposed end face of the scale 62 is blue. After scraping 8000 m, when the casing scraper is taken out, it is found that the end face of the scale 62 is yellow, and there is still a subsequent operation requirement of 7000 m. Then it is recommended that the scraper can be used once and then the scraping blade 6 be replaced. If a new scraping blade 6 is used for a certain well when it enters the well, after scraping 8000 m, when the casing scraper is taken out, it is found that the exposed end face of the scale 62 is still blue, and there is still a subsequent operation requirement of 7000 m. Then it can be used continuously. When the casing scraper is taken out, if the exposed end face of the scale 62 shows red, the scraper needs to be replaced immediately, and it is recommended to scrape again to ensure that the scraping effect meets the requirements of subsequent operations. Thus, the operator can reasonably arrange the replacement time of the scraping blade 6 in cooperation with the operation procedure, ensuring high-quality operation and improving operation efficiency.

[0044] Obviously, the above embodiments of the present invention are merely examples given to clearly illustrate the present invention, and are not intended to limit the implementation manners of the present invention. For those of ordinary skill in the art, various obvious changes, re-adjustments and substitutions can be made without departing from the protection scope of the present invention. It is not necessary and impossible to enumerate all implementation manners here. Any modifications, equivalent substitutions and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the claims of the present invention.

Claims

1. A casing scraper, used for cleaning the inner wall of the casing, characterized in that: include: A knife cage (1), wherein a groove (5) is arranged on the circumferential surface of the knife cage (1); an elastic member (2), one end of the elastic member (2) being connected to the groove (5), the other end of the elastic member (2) being connected to a scraper (6), and the elastic member (2) enabling the scraper (6) to maintain a tendency to extend out of the groove (5); a limiting pin (3), the limiting pin (3) passing through the scraper (6), at least one end of the limiting pin (3) extending into the knife cage (1) so as to limit the scraper (6) from extending out of the groove (5), the limiting pin (3) being made of a soluble metal material so as to be soluble in water or drilling fluid; An isolation layer (4), wherein the isolation layer (4) is arranged on the limiting pin (3) so as to isolate the limiting pin (3) from the external environment, and the isolation layer (4) is made of a phase change material.

2. The casing scraper according to claim 1, characterized in that: The grooves (5) are arranged in multiple groups along the axial direction of the knife cage (1); the multiple grooves (5) in the same group are located on the same outer diameter of the knife cage (1); and the multiple grooves (5) in different groups are staggeredly distributed along the axial direction of the knife cage (1).

3. The casing scraper according to claim 2, characterized in that: The projections of the scraper (6) in the groove (5) along the axial direction of the knife cage (1) collectively cover the inner wall of the sleeve.

4. The casing scraper according to claim 1, characterized in that: A first hole is provided on one side wall of the groove (5), and a second hole is provided on the other side wall opposite thereto. The first hole and / or the second hole penetrates the surface of the knife cage (1). A third hole is provided on the scraper (6). The limiting pin (3) penetrates the third hole, and its end is located in the first hole and the second hole.

5. The casing scraper according to claim 4, characterized in that: A sealing ring (8) is arranged in the first hole and / or the second hole.

6. The casing scraper according to claim 4, characterized in that: The isolation layer (4) comprises a first isolation layer (41) and a second isolation layer (42); the first isolation layer (41) is arranged between the scraper (6) and the side wall of the groove (5) and surrounds the limiting pin (3); the second isolation layer (42) blocks the first hole and / or the second hole.

7. The casing scraper according to claim 1, characterized in that: A limiting ring (7) is provided on the bottom wall of the groove (5), and the elastic member (2) is sleeved on the outer side of the limiting ring (7).

8. The casing scraper according to claim 1, characterized in that: The phase change temperature of the isolation layer (4) is 180°C-200°C.

9. The casing scraper according to claim 1, characterized in that: The scraper (6) comprises a blade body (61) and a scale (62); the blade body (61) is connected to the elastic member (2); a mounting hole is provided on a side of the blade body (61) facing away from the elastic member (2); the scale (62) is arranged in the mounting hole; and the scale (62) is divided into a plurality of wear identification sections along its length direction.

10. The casing scraper according to claim 9, characterized in that The colors of the plurality of wear identification segments are different from each other.

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