Two-stage variable diameter straightening device and use method

Abstract

The present invention relates to a petroleum cementing construction device and method, and in particular to a two-stage variable diameter straightening device and a method of use. The technical scheme is as follows: an elastic straightening arm is provided on the lower side of the upper joint, and the lower end of the elastic straightening arm is fixedly mounted on the upper slip sleeve, the upper slip sleeve is connected to the upper piston cylinder through the upper shear pin, and the upper slip sleeve is pushed to move by the upper annular piston; a rigid straightening arm is provided at the middle and lower part of the straightening device tube body, the lower end of the rigid straightening arm is in contact with and cooperates with the lower slip sleeve, and the lower slip sleeve is pushed to move by the lower annular piston. The beneficial effect is that the present invention forms a primary straightening system and a secondary straightening system, and the elastic straightening arm and the rigid straightening arm will be close to and supported on the open hole well wall after opening, ensuring that the casing string is centered in the open hole well wall, and finally forming a cement ring with uniform thickness in the annulus between the casing and the open hole well wall, thereby ensuring the cementing quality and improving the cementing quality rate.

Description

Technical Field

[0001] The invention relates to a petroleum cementing construction device and method, and in particular to a two-stage variable-diameter straightening device and a use method thereof. Background Art

[0002] During oil cementing construction, in horizontal wells and wells with large inclinations, the casing will sink to the lower part of the wellbore due to gravity, which makes the cement ring in the annulus at the lower end of the casing very thin, or even no cement ring in severe cases, affecting the bonding quality of the cement and the second interface and reducing the cementing quality rate. In order to improve the quality rate of cementing construction, a centralizer is installed on the casing lowered into the wellbore. The centralizer is a common tool in cementing construction and can improve the centering degree of the casing in the wellbore. The centralizers currently used can be divided into two categories, namely elastic centralizers and rigid centralizers. Among them, the most commonly used elastic centralizer is the bow casing centralizer. The bow casing centralizer consists of a round hoop and a bow-shaped spring sheet. The bow-shaped spring sheet is used to centralize the casing in the wellbore to ensure the centering of the casing. However, in actual horizontal wells and large-displacement wells, the vertical well section does not need to be centralized by the centralizer. The centralizer is really needed for centering in the inclined well section and the horizontal well section. When using the bow casing centralizer, it will be found that the bow casing centralizer The bow-shaped spring piece of the centralizer always presses against the inner wall of the wellbore from the beginning of entering the well, whether in the vertical well section, the inclined well section or the horizontal well section. Under the condition of central support by the bow-shaped spring piece, a large friction resistance will be generated as the casing is lowered, and the friction resistance will affect the casing lowering speed. If the drilling fluid is viscous, the friction resistance will be greater, and the casing string will be more difficult to lower, thereby further affecting the cementing efficiency. Although the rigid centralizer also has the above-mentioned problems of the bow-shaped casing centralizer, even if the ball rigid centralizer can reduce some friction resistance, due to its large outer diameter, it is easy to make the entire casing string appear very rigid, which is not flexible enough to use and difficult to lower the casing string. The applicable wellbore range is not wide enough, and it is still difficult to fundamentally solve the problem. Summary of the invention

[0003] The purpose of the present invention is to address the above-mentioned defects in the prior art and provide a two-stage variable diameter straightening device and a method of use, which can easily enter the well and improve the centering degree of the casing, thereby effectively improving the cementing quality rate.

[0004] The present invention mentions a two-stage variable-diameter straightening device, and its technical solution is: it includes a straightening device tube body, an upper joint, and a lower joint. The upper end of the straightening device tube body is provided with an upper joint, and the lower end is provided with a lower joint. It also includes an elastic straightening arm, an upper cava push sleeve, an upper shear pin, an upper piston cylinder, an upper annular piston, an upper liquid inlet hole, a rigid straightening arm, a lower cava push sleeve, a lower shear pin, a lower piston cylinder, a lower annular piston, and a lower liquid inlet hole. The lower side of the upper joint is provided with an elastic straightening arm, and the lower end of the elastic straightening arm is fixedly installed on the upper cava push sleeve. The upper cava push sleeve is connected to the upper piston cylinder through an upper shear pin. The upper piston cylinder It is installed on the upper outer wall of the centralizer tube body, an upper annular piston is provided between the upper piston cylinder and the centralizer tube body, and an upper liquid inlet hole is provided on the upper side of the centralizer tube body, and the upper slip sleeve is pushed to move by the upper annular piston; a rigid centralizing arm is provided at the middle and lower part of the centralizer tube body, and the lower end of the rigid centralizing arm is in contact with and cooperates with the lower slip sleeve, and the lower end of the lower slip sleeve is connected to the lower piston cylinder through a lower shear pin, and the lower piston cylinder is installed on the lower outer wall of the centralizer tube body, a lower annular piston is provided between the lower piston cylinder and the centralizer tube body, and a lower liquid inlet hole is provided on the lower side of the centralizer tube body, and the lower slip sleeve is pushed to move by the lower annular piston.

[0005] Preferably, the rigid righting arm is provided with four groups of V-grooves to form weak points, wherein the middle two groups of V-grooves are located on the inner side of the rigid righting arm, and the V-grooves at both ends are located on the outside of the rigid righting arm. Under the action of the pressure difference, the lower piston cylinder pushes the lower cava push sleeve upward through the lower annular piston, driving the rigid righting arm to extend outward along the two middle groups of V-grooves to form a trapezoidal structure.

[0006] Preferably, upper O-rings are provided on both sides of the upper annular piston, and lower O-rings are provided on both sides of the lower annular piston.

[0007] Preferably, a circle of straightening blocks is provided on the outer wall of the straightening device tube body at the lower part of the upper piston cylinder.

[0008] Preferably, a plurality of balls are embedded in the outer wall of the straightening block.

[0009] Preferably, the middle inner wall of the upper piston cylinder is provided with an upper groove, and the outer wall of the upper annular piston is installed with an upper retaining spring. When the upper annular piston moves upward, the upper retaining spring moves to the upper groove to lock the upper annular piston, thereby locking the elastic righting arm.

[0010] Preferably, the middle inner wall of the lower piston cylinder is provided with a lower groove, and the outer wall of the lower annular piston is installed with a lower retaining spring. When the lower annular piston moves upward, the lower retaining spring moves to the lower groove to lock the lower annular piston, thereby locking the rigid righting arm.

[0011] The present invention provides a method for using a two-stage variable diameter straightening device, comprising the following steps:

[0012] When lowering into the well, the casing together with the two-stage variable diameter straightening device is lowered into the well on the ground. At this time, the elastic straightening arm and the rigid straightening arm are in a contracted state, and the straightening block is embedded with a ball. The resistance of the casing and the straightening device body to lowering is small until they are lowered into the predetermined position.

[0013] Then, displacement cement is injected along the casing on the ground, and the displacement cement enters the upper piston cylinder along the upper liquid inlet hole. When the pressure rises to a certain value, the upper shear pin is sheared off, and the upper annular piston pushes the upper slip sleeve to move upward, thereby pushing the elastic righting arm to expand, and the upper retaining spring moves into the upper retaining groove to lock the upper annular piston, so that the elastic righting arm maintains an arc-shaped expanded state; in addition, the displacement cement enters the lower piston cylinder along the lower liquid inlet hole. When the pressure rises to a certain value, the lower shear pin is sheared off, and the lower annular piston pushes the lower slip sleeve to move upward, thereby pushing the rigid righting arm to deform along the weak point of the V-shaped groove to form an outward trapezoidal structure, and the lower retaining spring locks the lower annular piston when it moves to the lower retaining groove, so that the rigid righting arm maintains a trapezoidal structure;

[0014] The casing is straightened through the upper and lower stages of straightening. After opening, the elastic straightening arm and the rigid straightening arm will be close to and supported on the open hole wall, ensuring that the casing string is centered in the wellbore. Finally, a cement ring with uniform thickness is formed in the annulus between the casing and the open hole wall, ensuring the cementing quality.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0016] A radial rigid righting arm and an elastic righting arm are respectively arranged on the outer wall of the tube body of the two-stage variable diameter righting device, forming a first-stage righting system and a second-stage righting system. Upper and lower piston cylinders are installed on the outer wall of the tube body of the righting device, and upper and lower annular pistons and upper and lower slip push sleeves are arranged in the upper and lower piston cylinders. The elastic righting arm and the rigid righting arm will be close to and supported on the open hole wall after opening, so as to ensure that the casing string is centered in the open hole wall, and finally a cement ring with uniform thickness is formed in the annulus between the casing and the open hole wall, so as to ensure the cementing quality. Upper and lower retaining springs are arranged on the upper and lower annular pistons to cooperate with upper and lower retaining grooves, which can effectively prevent the rigid righting arm and the elastic righting arm from being squeezed and withdrawn after opening, thereby improving the righting reliability of the device and thus improving the cementing quality rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the structure of the present invention during the process of being lowered into a well;

[0018] Figure 2 It is a schematic diagram of the structure of opening the two-stage righting after the present invention is lowered into the well;

[0019] Figure 3It is a schematic diagram of the local structure before the rigid righting arm expands;

[0020] Figure 4 It is a schematic diagram of the local structure after the rigid righting arm is expanded;

[0021] Figure 5 It is a schematic diagram of the local structure before the elastic righting arm expands;

[0022] Figure 6 It is a schematic diagram of the local structure after the elastic righting arm is expanded;

[0023] Figure 7 It is an enlarged schematic diagram of the upper retaining spring and the lower retaining groove before the elastic righting arm is expanded;

[0024] Figure 8 It is a schematic diagram of the cooperation between the upper retaining spring and the lower retaining groove after the elastic righting arm is expanded;

[0025] Fig. 9 It is an enlarged schematic diagram of the four groups of V-shaped grooves on the rigid righting arm;

[0026] Fig.10 It is a schematic diagram of the structure of the present invention after rotatable swirl righting blocks are respectively installed at both ends;

[0027] Fig.11 It is a structural schematic diagram of a rotatable swirl righting block;

[0028] Fig.12 1 is a schematic diagram of a rotatable swirl straightening block in a top view;

[0029] Fig.13 is a schematic diagram of the structure of Embodiment 3 of the present invention;

[0030] Fig.14 It is a schematic diagram of a pressure holding ball seat and a pressure holding ball;

[0031] In the above figure: elastic righting arm 1, upper slip sleeve 2, upper shear pin 3, upper piston cylinder 4, upper O-ring 5, upper annular piston 6, upper liquid inlet hole 7, rigid righting arm 8, lower slip sleeve 9, lower shear pin 10, lower piston cylinder 11, lower O-ring 12, lower annular piston 13, lower liquid inlet hole 14, righting device body 15, upper joint 16, lower joint 17, righting block 18, rotatable swirl righting block 19, pressure holding ball seat 20, pressure holding ball 21, upper groove 4.1, upper retaining spring 6.1, V-groove 8.1, lower groove 11.1, lower retaining spring 13.1, ball 18.1. DETAILED DESCRIPTION

[0032] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0033] Example 1, reference Figure 1-Figure 9 The present invention relates to a two-stage variable diameter straightening device, comprising a straightening device body 15, an upper joint 16 and a lower joint 17. The upper end of the straightening device body 15 is provided with an upper joint 16, and the lower end is provided with a lower joint 17. The device body 15 also comprises an elastic straightening arm 1, an upper slip sleeve 2, an upper shear pin 3, an upper piston cylinder 4, an upper annular piston 6, an upper liquid inlet hole 7, a rigid straightening arm 8, a lower slip sleeve 9, a lower shear pin 10, a lower piston cylinder 11, a lower annular piston 13 and a lower liquid inlet hole 14. The lower side of the upper joint 16 is provided with an elastic straightening arm 1, and the lower end of the elastic straightening arm 1 is fixedly mounted on the upper slip sleeve 2. The upper slip sleeve 2 is connected to the upper piston cylinder 4 through the upper shear pin 3. The upper piston cylinder 4 is mounted on the straightening device body 15. An upper annular piston 6 is provided on the upper outer wall of the centralizer tube body 15 between the upper piston cylinder 4 and the centralizer tube body 15, and an upper liquid inlet hole 7 is provided on the upper side of the centralizer tube body 15, and the upper cava push sleeve 2 is pushed to move by the upper annular piston 6; a rigid centralizing arm 8 is provided at the middle and lower part of the centralizer tube body 15, and the lower end of the rigid centralizing arm 8 is in contact with and cooperates with the lower cava push sleeve 9, and the lower end of the lower cava push sleeve 9 is connected to the lower piston cylinder 11 through a lower shear pin 10, and the lower piston cylinder 11 is installed on the lower outer wall of the centralizer tube body 15, and a lower annular piston 13 is provided between the lower piston cylinder 11 and the centralizer tube body 15, and a lower liquid inlet hole 14 is provided on the lower side of the centralizer tube body 15, and the lower cava push sleeve 9 is pushed to move by the lower annular piston 13.

[0034] Among them, the above-mentioned rigid righting arm 8 is provided with four groups of V-shaped grooves 8.1 to form weak points, among which the middle two groups of V-shaped grooves 8.1 are located on the inner side of the rigid righting arm 8, and the V-shaped grooves 8.1 at both ends are located outside the rigid righting arm 8. Under the action of the pressure difference, the lower piston cylinder 11 pushes the lower cava push sleeve 9 upward through the lower annular piston 13, driving the rigid righting arm 8 to extend outward along the two middle groups of V-shaped grooves 8.1 to form a trapezoidal structure.

[0035] In addition, upper O-rings 5 ​​are provided on both sides of the upper annular piston 6, and lower O-rings 12 are provided on both sides of the lower annular piston 13, which can achieve a better sealing effect.

[0036] A circle of straightening blocks 18 is arranged on the outer wall of the straightening device tube body 15 at the lower part of the upper piston cylinder 4. A plurality of balls 18.1 are embedded on the outer wall of the straightening blocks 18, which can greatly reduce the resistance.

[0037] Reference Figure 7 and Figure 8The middle inner wall of the upper piston cylinder 4 of the present invention is provided with an upper groove 4.1, and the outer wall of the upper annular piston 6 is installed with an upper retaining spring 6.1. When the upper annular piston 6 moves upward, the upper retaining spring 6.1 is moved to the upper groove 4.1 to lock the upper annular piston 6, thereby locking the elastic righting arm 1, wherein the elastic righting arm is made of spring steel sheet.

[0038] In addition, a lower retaining groove 11.1 is provided on the middle inner wall of the lower piston cylinder 11, and a lower retaining spring 13.1 is installed on the outer wall of the lower annular piston 13. When the lower annular piston 13 moves upward, the lower retaining spring 13.1 moves to the lower retaining groove 11.1 to lock the lower annular piston 13, thereby locking the rigid straightening arm 8.

[0039] The present invention provides a method for using a two-stage variable diameter straightening device, comprising the following steps:

[0040] When lowering into the well, the casing together with the two-stage variable diameter straightening device is lowered into the well on the ground. At this time, the elastic straightening arm 1 and the rigid straightening arm 8 are in a contracted state, and the straightening block 18 is embedded with a ball 18.1. The resistance of the casing and the straightening device body 15 to lowering is small until they are lowered into the predetermined position.

[0041] Then, displacement cement is injected along the casing on the ground, and the displacement cement enters the upper piston cylinder 4 along the upper liquid inlet hole 7. When the pressure rises to a certain value, the upper shear pin 3 is sheared off, and the upper annular piston 6 pushes the upper slip sleeve 2 to move upward, thereby pushing the elastic righting arm 1 to expand, and the upper retaining spring 6.1 moves into the upper clamping groove 4.1 to lock the upper annular piston 6, so that the elastic righting arm 1 maintains an arc-shaped expanded state; in addition, the displacement cement enters the lower piston cylinder 11 along the lower liquid inlet hole 14. When the pressure rises to a certain value, the lower shear pin 10 is sheared off, and the lower annular piston 13 pushes the lower slip sleeve 9 to move upward, thereby pushing the rigid righting arm 8 to deform along the V-shaped groove 8.1 to form a weak point to form an outward trapezoidal structure, and the lower retaining spring 13.1 locks the lower annular piston 13 when it moves to the lower clamping groove 11.1, so that the rigid righting arm 8 maintains a trapezoidal structure;

[0042] The casing is straightened by the upper and lower two-stage straightening. The elastic straightening arm 1 and the rigid straightening arm 8 will be close to and supported on the open hole wall after opening, ensuring that the casing string is centered in the wellbore. Finally, a cement ring with uniform thickness is formed in the annulus between the casing and the open hole wall, ensuring the cementing quality.

[0043] Embodiment 2, a two-stage variable diameter straightening device mentioned in the present invention comprises a straightening device body 15, an upper joint 16, and a lower joint 17. The upper end of the straightening device body 15 is provided with an upper joint 16, and the lower end is provided with a lower joint 17. It also comprises an elastic straightening arm 1, an upper cava push sleeve 2, an upper shear pin 3, an upper piston cylinder 4, an upper annular piston 6, an upper liquid inlet hole 7, a rigid straightening arm 8, a lower cava push sleeve 9, a lower shear pin 10, a lower piston cylinder 11, a lower annular piston 13, and a lower liquid inlet hole 14. The lower side of the upper joint 16 is provided with an elastic straightening arm 1, and the lower end of the elastic straightening arm 1 is fixedly mounted on the upper cava push sleeve 2. The upper cava push sleeve 2 is connected to the upper piston cylinder 4 through the upper shear pin 3. The upper piston cylinder 4 is installed An upper annular piston 6 is provided on the upper outer wall of the centralizer tube body 15, between the upper piston cylinder 4 and the centralizer tube body 15, and an upper liquid inlet hole 7 is provided on the upper side of the centralizer tube body 15, and the upper slip sleeve 2 is pushed to move by the upper annular piston 6; a rigid centralizing arm 8 is provided in the middle and lower part of the centralizer tube body 15, and the lower end of the rigid centralizing arm 8 is in contact with and cooperates with the lower slip sleeve 9, and the lower end of the lower slip sleeve 9 is connected to the lower piston cylinder 11 through a lower shear pin 10, and the lower piston cylinder 11 is installed on the lower outer wall of the centralizer tube body 15, and a lower annular piston 13 is provided between the lower piston cylinder 11 and the centralizer tube body 15, and a lower liquid inlet hole 14 is provided on the lower side of the centralizer tube body 15, and the lower slip sleeve 9 is pushed to move by the lower annular piston 13.

[0044] The difference from Example 1 is:

[0045] Rotatable swirl straightening blocks 19 can be installed at the upper and lower ends of the device. Figure 10-11 It has a built-in bearing and a swirl strip design on the outside. When it comes into contact with the drilling fluid when lowered into the well, the straightening block can rotate under the action of the bearing and the swirl strip, which plays a role in stirring the drilling fluid and circulating the mud. Even if the drilling fluid density is high and the fluid is very viscous, the casing string can be lowered into the well faster and more smoothly. Because the upper and lower ends of the device are equipped with rotatable swirl straightening blocks 19, and the outer diameter of the rotatable swirl straightening block 19 is slightly larger, it can also protect the present invention from being bumped by debris such as gravel during the lowering process.

[0046] Embodiment 3, a two-stage variable diameter straightening device mentioned in the present invention comprises a straightening device body 15, an upper joint 16, and a lower joint 17, wherein the upper end of the straightening device body 15 is provided with an upper joint 16, and the lower end is provided with a lower joint 17, wherein the device also comprises an elastic straightening arm 1, an upper cava push sleeve 2, an upper shear pin 3, an upper piston cylinder 4, an upper annular piston 6, an upper liquid inlet hole 7, a rigid straightening arm 8, a lower cava push sleeve 9, a lower shear pin 10, a lower piston cylinder 11, a lower annular piston 13, and a lower liquid inlet hole 14, wherein an elastic straightening arm 1 is provided on the lower side of the upper joint 16, and the lower end of the elastic straightening arm 1 is fixedly mounted on the upper cava push sleeve 2, the upper cava push sleeve 2 is connected to the upper piston cylinder 4 through the upper shear pin 3, and the upper piston cylinder 4 is mounted An upper annular piston 6 is provided on the upper outer wall of the centralizer tube body 15, between the upper piston cylinder 4 and the centralizer tube body 15, and an upper liquid inlet hole 7 is provided on the upper side of the centralizer tube body 15, and the upper slip sleeve 2 is pushed to move by the upper annular piston 6; a rigid centralizing arm 8 is provided in the middle and lower part of the centralizer tube body 15, and the lower end of the rigid centralizing arm 8 is in contact with and cooperates with the lower slip sleeve 9, and the lower end of the lower slip sleeve 9 is connected to the lower piston cylinder 11 through a lower shear pin 10, and the lower piston cylinder 11 is installed on the lower outer wall of the centralizer tube body 15, and a lower annular piston 13 is provided between the lower piston cylinder 11 and the centralizer tube body 15, and a lower liquid inlet hole 14 is provided on the lower side of the centralizer tube body 15, and the lower slip sleeve 9 is pushed to move by the lower annular piston 13.

[0047] The difference from Example 2 is:

[0048] Reference Figure 13-Figure 14 A pressure-holding ball seat 20 is installed at the lower joint 17 at the bottom of Example 2, and a pressure-holding ball 21 is dropped into the well after being lowered to a predetermined position. The pressure-holding ball seat 20 and the pressure-holding ball 21 form a seal to ensure that the pressure in the casing string increases.

[0049] After reaching the predetermined position, the present invention throws the pressure-holding ball 21 to hold the pressure. When the pressure rises to a certain value, the drilling fluid enters the annular liquid cylinder through the liquid inlet hole. Under the action of the pressure difference, the annular piston moves up, and the annular piston pushes the slip sleeve, and the slip sleeve pushes the rigid straightening arm and the elastic straightening arm to move up. When it moves up to the designed position, the straightening arm stops moving up. Under the continued push of the slip sleeve, the straightening arm is compressed and stretched open, holding up the casing to play a straightening role. After that, continue to pressurize. When the pressure rises to a certain level again, the shear pin of the pressure-holding ball seat can be sheared off, the pressure-holding ball seat can be opened, the pressure-holding ball and the sealing assembly fall into the well, and the casing string and the annulus are recirculated. The use of the pressure-holding ball seat and the pressure-holding ball seal can ensure that the pressure in the casing string reaches a predetermined level, and ensure that the pressure is sufficient to open the straightening arm.

[0050] The present invention is provided with an upper and lower two-stage variable diameter straightening system, which has a large straightening action area and strong thrust, and can lift the casing with a relatively small pressure to play a straightening role. The expanded outer diameter of the straightener can be larger than the inner diameter of the upper layer of casing, and the straightening effect can be achieved for wellbores with irregular wellbores and expanded diameters. After opening, the straightening arm will be close to and supported on the open hole wall without being inserted into the wall, ensuring that the casing string is centered in the wellbore, and finally forming a cement ring with uniform thickness in the annulus, greatly improving the cementing quality rate.

[0051] The above are only some preferred embodiments of the present invention. Any person skilled in the art may modify the above technical solutions or modify them into equivalent technical solutions. Therefore, the corresponding simple modifications or equivalent transformations made according to the technical solutions of the present invention shall fall within the scope of protection claimed by the present invention.

Claims

1. A two-stage variable diameter straightening device, comprising a straightening device tube body (15), an upper joint (16), and a lower joint (17), wherein the upper end of the straightening device tube body (15) is provided with an upper joint (16), and the lower end is provided with a lower joint (17), wherein: The invention also comprises an elastic righting arm (1), an upper slip sleeve (2), an upper shear pin (3), an upper piston cylinder (4), an upper annular piston (6), an upper liquid inlet hole (7), a rigid righting arm (8), a lower slip sleeve (9), a lower shear pin (10), a lower piston cylinder (11), a lower annular piston (13), and a lower liquid inlet hole (14). The lower side of the upper joint (16) is provided with an elastic righting arm (1), and the lower end of the elastic righting arm (1) is fixedly mounted on the upper slip sleeve (2). The upper slip sleeve (2) is connected to the upper piston cylinder (4) through the upper shear pin (3). The upper piston cylinder (4) is mounted on the upper outer wall of the centralizer tube body (15). An upper annular righting arm (14) is provided between the upper piston cylinder (4) and the centralizer tube body (15). A plug (6) is provided on the upper side of the centralizer tube body (15), and an upper liquid inlet hole (7) is provided on the upper side of the centralizer tube body (15), and the upper slip sleeve (2) is pushed to move by the upper annular piston (6); a rigid centralizing arm (8) is provided at the middle and lower part of the centralizer tube body (15), and the lower end of the rigid centralizing arm (8) is in contact with and cooperates with the lower slip sleeve (9), and the lower end of the lower slip sleeve (9) is connected to the lower piston cylinder (11) through a lower shear pin (10), and the lower piston cylinder (11) is installed on the lower outer wall of the centralizer tube body (15), and a lower annular piston (13) is provided between the lower piston cylinder (11) and the centralizer tube body (15), and a lower liquid inlet hole (14) is provided on the lower side of the centralizer tube body (15), and the lower slip sleeve (9) is pushed to move by the lower annular piston (13).

2. The two-stage variable diameter straightening device according to claim 1 is characterized in that: The rigid righting arm (8) is provided with four groups of V-shaped grooves (8.1) to form weak points, wherein the middle two groups of V-shaped grooves (8.1) are located on the inner side of the rigid righting arm (8), and the V-shaped grooves (8.1) at both ends are located outside the rigid righting arm (8). Under the action of the pressure difference, the lower piston cylinder (11) pushes the lower cava push sleeve (9) upward through the lower annular piston (13), driving the rigid righting arm (8) to extend outward along the two middle groups of V-shaped grooves (8.1), thereby forming a trapezoidal structure.

3. The two-stage variable diameter straightening device according to claim 2 is characterized in that: Upper O-type sealing rings (5) are provided on both sides of the upper annular piston (6), and lower O-type sealing rings (12) are provided on both sides of the lower annular piston (13).

4. The two-stage variable diameter straightening device according to claim 3 is characterized in that: A circle of straightening blocks (18) is provided on the outer wall of the straightening device tube body (15) at the lower part of the upper piston cylinder (4).

5. The two-stage variable diameter straightening device according to claim 4 is characterized in that: A plurality of balls (18.1) are embedded in the outer wall of the straightening block (18).

6. The two-stage variable diameter straightening device according to claim 5 is characterized in that: An upper retaining groove (4.1) is provided on the middle inner wall of the upper piston cylinder (4), and an upper retaining spring (6.1) is installed on the outer wall of the upper annular piston (6). When the upper annular piston (6) moves upward, the upper retaining spring (6.1) locks the upper annular piston (6) when it moves to the upper retaining groove (4.1), thereby locking the elastic righting arm (1).

7. The two-stage variable diameter straightening device according to claim 6 is characterized in that: A lower retaining groove (11.1) is provided on the middle inner wall of the lower piston cylinder (11), and a lower retaining spring (13.1) is installed on the outer wall of the lower annular piston (13). When the lower annular piston (13) moves upward, the lower retaining spring (13.1) locks the lower annular piston (13) when it moves to the lower retaining groove (11.1), thereby locking the rigid righting arm (8).

8. The method for using the two-stage variable diameter straightening device according to claim 7 is characterized by: The process includes: When lowering into the well, the casing together with the two-stage variable diameter straightening device is lowered into the well on the ground. At this time, the elastic straightening arm (1) and the rigid straightening arm (8) are in a contracted state, and a ball (18.1) is embedded in the straightening block (18). The casing and the straightening device body (15) have little resistance to lowering until they are lowered into a predetermined position. Then, displacement cement is injected along the casing on the ground, and the displacement cement enters the upper piston cylinder (4) along the upper liquid inlet hole (7). When the pressure rises to a certain value, the upper shear pin (3) is sheared off, and the upper annular piston (6) pushes the upper slip sleeve (2) to move upward, thereby pushing the elastic righting arm (1) to expand, and the upper retaining spring (6.1) moves into the upper retaining groove (4.1) to lock the upper annular piston (6), so that the elastic righting arm (1) maintains the arc-shaped expanded state; in addition, the displacement cement The liquid enters the lower piston cylinder (11) along the lower liquid inlet hole (14). When the pressure rises to a certain value, the lower shear pin (10) is sheared off, and the lower annular piston (13) pushes the lower slip sleeve (9) to move upward, thereby pushing the rigid righting arm (8) to deform along the V-shaped groove (8.1) to form a weak point, forming an outward trapezoidal structure, and the lower retaining spring (13.1) locks the lower annular piston (13) when it moves to the lower retaining groove (11.1), so that the rigid righting arm (8) maintains the trapezoidal structure; The casing is straightened by the upper and lower two-stage straightening. After being opened, the elastic straightening arm (1) and the rigid straightening arm (8) will be close to and supported on the open hole wall, ensuring that the casing string is centered in the wellbore. Finally, a cement ring with uniform thickness is formed in the annulus between the casing and the open hole wall, thereby ensuring the cementing quality.

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