Sealing working barrel suspension device for old well and construction method of sealing working barrel suspension device

Abstract

The invention relates to a sealing working barrel suspension device for an old well and a construction method thereof, an external releasing pipe string and an internal lifting pipe string are arranged in the device, and an upper expansion pipe, an upper outer barrel, a lower outer barrel and a lower expansion pipe in the external releasing pipe string are sequentially connected from top to bottom; the internal pipe string capable of being lifted comprises an inner cylinder, a lock cylinder and a ball seat, and the inner cylinder can be in threaded connection with the booster through booster connecting threads; when a limiting head connected with the lower portion of the lock cylinder is bound in a pawl of the inner cylinder, a lock ball in the cylinder wall of the lock cylinder can fix the lock cylinder and the inner cylinder together through a first lock ball groove. When the pressing ball is thrown in to knock off the ball seat, the ball seat releases the locking ball through the second locking ball groove in the falling process, and the locking ball can move downwards along with the locking cylinder to be hung on the hanging step of the inner cylinder. The combined sealing device can be permanently hung in the inner wall of a sleeve of an old well, an effective anchoring point is provided for a later injection-production pipe column, and the problem that a sealing working barrel in an existing combined sealing device can only be applied in a well cementation mode and cannot be applied to the old well is solved.

Description

Technical Field

[0001] The present invention relates to the field of gas storage construction in oilfield development, and particularly to a sealing work barrel hanging device for old wells and its construction method. Background Art

[0002] With the increasing number of gas storage facilities established in China, some problems have gradually emerged in the completed gas storage facilities. Most of the injection-production string in existing gas storage facilities uses gas-tight packers to seal the annulus between the casing and tubing, such as the following patented technologies: CN112647857B "Injection-Production String and Completion Method Using the Same" and CN206205797U "A Completion String for an Oil and Gas Reservoir Type Gas Storage Well".

[0003] However, due to the different injection-production cycles and working conditions of various gas storage facilities, some gas storage facilities have the problem of casing with pressure. A large part of the reason for this problem is that the working environment of the injection-production string is harsh. As described in articles such as "Research on the Dynamic Characteristics of Fluid-Induced Vibration and Buckling of Injection-Production String in Gas Storage" and "Buckling Behavior of Tubing in Gas Storage under Multi-Cycle Injection-Production Conditions", the working state of the injection-production string under harsh working conditions is fully analyzed and described. Under such working conditions, the gas-tight packers in the injection-production string are extremely prone to failure, resulting in the loss of sealing of the annulus between the casing and tubing.

[0004] Therefore, the advantage of using a combination seal of a sealing work barrel and a sealing plug instead of a gas-tight packer is gradually shown. First, the sealing surface of the sealing work barrel is precision machined, and its roughness is far from comparable to that of the inner wall of a conventional casing. The cooperation between it and the rubber ring on the sealing plug can effectively improve the sealing grade and service life. Second, when the rubber ring on the sealing plug reaches the end of its service life and fails, only the sealing plug needs to be pulled out and the O-ring needs to be replaced, and the maintenance cost is extremely low. Unlike a gas-tight packer, whether the anchoring module or the sealing module fails, the entire packer needs to be pulled out and replaced.

[0005] In summary, the combination seal of the sealing work barrel and the sealing plug will surely be widely promoted and applied in the visible future. However, since the sealing work barrel often needs to be connected to the completion string and its anchoring stability is ensured by cementing, the current use of the sealing work barrel is limited to new wells, and in some cases where it is applied to old wells, it is also implemented by using small casing cementing. Therefore, its application scope is greatly limited, especially in some small-sized wellbores with small diameters. Therefore, there is an urgent need for a new sealing work barrel hanging device to solve the above problems. Summary of the Invention

[0006] To solve the above problems, the present invention provides a suspension device for a sealing working barrel of an old well and its construction method, expands the application fields and scopes of low-cost combined sealing devices, uses the combined sealing device instead of a packer, thereby reducing the completion production cost and the later operation and maintenance cost, and at the same time improving the utilization rate of old wells and the economic benefits.

[0007] To achieve the above object, the present invention adopts the following technical solutions: A suspension device for a sealing working barrel of an old well is provided with an external release string and an internal retrievable string. Among them: The external release string includes an upper expansion head and a lower expansion head, an upper expansion pipe and a lower expansion pipe, and an upper outer barrel and a lower outer barrel. The upper expansion pipe, the upper outer barrel, the lower outer barrel, and the lower expansion pipe are connected in sequence from top to bottom; An upper locking ring, a middle locking ring, and a lower locking ring are respectively clamped and installed between the upper expansion cylinder and the upper outer barrel, the upper outer barrel and the lower outer barrel, and the lower outer barrel and the lower expansion cylinder; The middle locking ring is machined with threads and can be threadedly connected to the sealing insertion tube in the combined sealing device; The upper expansion head and the lower expansion head are respectively inserted from the other ends of the upper expansion pipe and the lower expansion pipe and are respectively matched with the upper locking ring and the lower locking ring; The internal retrievable string includes an inner barrel, a locking barrel, and a ball seat. The upper part of the inner barrel is provided with a booster connection thread, the lower part is provided with a pawl, and the inner cavity is provided with a first locking ball groove and a suspension step. The inner barrel can be threadedly connected to the booster through the booster connection thread; A second locking ball groove is provided in the ball seat installed on the upper part of the locking barrel. The ball seat is connected to the inner barrel by a shear pin; When the limit head connected to the lower part of the locking barrel is constrained in the pawl of the inner barrel, the locking ball in the locking barrel wall can fix the locking barrel and the inner barrel together through the first locking ball groove; When a pressure ball is put in and the ball seat is knocked off, the ball seat releases the locking ball through the second locking ball groove during the falling process and can move down together with the locking barrel and be suspended on the suspension step of the inner barrel.

[0008] Preferably, the inner circles of the upper locking ring and the lower locking ring are both machined with serrations and can be respectively matched with the serrations on the outer circles of the upper expansion head and the lower expansion head.

[0009] Preferably, the middle locking ring is a broken ring provided with an axial cut. The cut provided axially is an oblique cut or a vertical cut, and the oblique angle is set between 1 degree and 89 degrees; The outer diameter of the middle locking ring in the natural state is smaller than the inner diameter of the upper outer barrel section where it is located; The inner circle of the middle locking ring is machined with threads capable of connecting to the sealing insertion tube in the combined sealing device, and the top is machined with a torque transmission spline. The torque transmission spline at the top of the middle locking ring can be matched with the torque transmission spline in the upper outer barrel.

[0010] Preferably, both the upper expansion head and the lower expansion head are of cylindrical structures and their outer circles are non-uniform-diameter outer circles. Between the large-diameter outer-circle section and the small-diameter outer-circle section of the upper expansion head is a tensioning conical surface, and in the small-diameter outer-circle section, there are bayonet catches that can cooperate with the upper locking ring; in the lower end inner circle of the lower expansion head, there is a groove for the end of the ratchet pawl to be embedded. On the lower outer circle of the lower expansion head, there are an expansion tube mating step and tensioning steps of the second level or above. Between the expansion tube mating step and the tensioning steps is a tensioning conical surface. The tensioning conical surfaces in the outer circles of the upper expansion head and the lower expansion head are arranged facing each other; on the upper outer circle of the lower expansion head, there are bayonet catches that can cooperate with the lower locking ring.

[0011] Preferably, both the upper expansion tube and the lower expansion tube are of non-uniform-diameter cylindrical structures, and tensioning mating conical surfaces are provided in the inner circles of the upper expansion tube and the lower expansion tube; the tensioning mating conical surfaces in the upper expansion tube and the lower expansion tube are arranged back to back and can respectively cooperate with the tensioning conical surfaces in the upper expansion head and the lower expansion head. The bayonet catches in the upper expansion tube and the lower expansion tube can respectively cooperate with the bayonet catches in the upper locking ring and the lower locking ring.

[0012] Preferably, upper outer cylinder limiting steps and lower outer cylinder limiting steps are respectively provided on the outer circles of the upper expansion tube and the lower expansion tube; on the outer circle of the upper expansion tube above the upper outer cylinder limiting step, a metal sealing ring groove, a rubber sealing ring groove, and an expanded-diameter strain groove are successively arranged from bottom to top. A metal sealing ring and a rubber sealing ring are respectively installed in the metal sealing ring groove and the rubber sealing ring groove; on the outer circle of the lower expansion tube below the lower outer cylinder limiting step, a metal sealing ring groove, a rubber sealing ring groove, and an expanded-diameter strain groove are also successively arranged from top to bottom, and a metal sealing ring and a rubber sealing ring are respectively installed in the metal sealing ring groove and the rubber sealing ring groove; the groove depth of the expanded-diameter strain groove in the outer circles of the upper expansion tube and the lower expansion tube is set between 2 mm and 5 mm.

[0013] Preferably, the upper outer cylinder is a non-uniform-diameter cylinder body and has internal threads at both ends and can be respectively thread-connected to the upper expansion tube and the lower outer cylinder; in the inner circle of the upper outer cylinder, an upper locking ring installation cavity, a locking ring separating platform, and a middle locking ring installation cavity are also provided from top to bottom. In the lower part of the body of the locking ring separating platform, there is a torque-transmitting spline, and the torque-transmitting spline in the body of the locking ring separating platform can cooperate with the torque-transmitting spline at the top of the middle locking ring. After cooperation, the middle locking ring is exactly located in the middle locking ring installation cavity in the upper outer cylinder.

[0014] Preferably, the lower outer cylinder is of a non-uniform-diameter cylindrical structure, with external threads and internal threads processed at the upper and lower ends respectively. The upper inner cavity of the lower outer cylinder is a conical cavity, and above the lower-end internal thread section is a lower locking ring installation cavity; the smallest inner circle surface in the lower outer cylinder is a sealing surface.

[0015] Preferably, the ball seat is a non-uniform diameter cylinder, the upper inner cavity of the ball seat is a conical cavity and the minimum inner diameter is smaller than the outer diameter of the pressure ball; a sealing ring groove and a shear pin hole or shear pin groove are provided on the outer circle of the upper part of the ball seat, and the second locking ball groove is arranged in the outer circle of the lower part of the ball seat; when the ball seat is connected to the inner cylinder by a shear pin, the second locking ball groove is located above the locking ball.

[0016] Preferably, the locking cylinder is a non-uniform diameter cylinder, the upper inner cavity of the locking cylinder is a ball seat fitting cavity and a locking ball assembly hole is provided in the cylinder wall of the upper inner cavity; a sealing ring groove is provided on the outer circle of the locking cylinder below the locking ball assembly hole, and the upper outer circle of the locking cylinder can be installed in the inner cylinder and can be suspended on the suspension step of the inner cylinder.

[0017] Preferably, an external thread is provided on the outer circle of the lower part of the locking cylinder and can be threadedly connected to the limit head, and a lock washer is also threadedly connected below the limit head; the limit head is a non-uniform diameter cylinder and is provided with an internal thread, and the outer conical surface that can conform to the inner wall taper of the ratchet pawl is between the large diameter section and the small diameter section of the outer circle of the limit head.

[0018] A construction method for a suspension device of a sealing working barrel for an old well comprises the following steps: A. Assemble the inner cylinder in the suspension device of the sealing working barrel with the connecting inner pipe in the booster connected to the lower end of the service string and lower it to a predetermined position in the well; B. After reaching the predetermined position in the well, apply pressure from the ground to preliminarily anchor the suspension device of the sealing working barrel at the predetermined position in the well; C. Increase the pressure of the booster to anchor the external release string in the suspension device of the sealing working barrel at the predetermined position in the well; D. Pull out the internally retrievable string to release the external release string, and permanently leave the external release string in the well for use as the sealing working barrel of the combined sealing device.

[0019] Compared with the prior art, the present invention has the following remarkable usage effects: (1) The device of the present invention can be used in cooperation with a booster to permanently suspend the seal working barrel suspension device in the inner wall of the casing of an old well, providing an effective anchoring point for the later injection and production string, and solving the problem that the seal working barrel in the existing combined seal device can only be applied by cementing and cannot be applied to old wells; (2) The device of the present invention is provided with an external release string and an internal retrievable string. In the external release string, a combination of components such as an upper expansion pipe, a lower expansion pipe, an upper locking ring, and a lower locking ring is adopted to achieve double anchoring and sealing of the material body and multiple locking rings, greatly improving the service life of the external release string in the present invention; (3) In the present invention, by applying the locking ring, the problem that the upper expansion head and the lower expansion head may become loose is solved, effectively achieving the purpose of permanently anchoring the external release string underground; (4) The device of the present invention can be connected to the lower end of the service string. After applying force through a booster, the upper expansion pipe and the lower expansion pipe are extruded and expanded from both ends of the device, permanently suspending the external release string in the old well without the need to be fixed by cementing, expanding the application range of the downhole combined seal device.

[0020] By using the device of the present invention, the application field and scope of the low-cost combined seal device are effectively expanded, enabling the combined seal device to replace the packer, effectively reducing the application cost. While effectively reducing the well completion production cost and the later operation and maintenance cost, the utilization rate of old wells is improved. For old wells, it has a significant role in tapping potential and increasing efficiency, and can generate significant economic and social benefits, with a huge promotion space. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The drawings are used to provide a further understanding of the present invention, and constitute a part of the specification. They are used together with the embodiments of the present invention to explain the present invention, and do not constitute a limitation to the present invention. In the drawings: Figure 1 is a schematic structural view of the seal working barrel suspension device of the present invention; Figure 2 is a schematic structural view of the present invention after being connected to a booster; Figure 3 is Figure 1 a schematic structural view of the upper outer barrel in Figure 4 is Figure 1 a schematic structural view of the middle locking ring in Figure 5 is Figure 1 a schematic structural view of the inner barrel in Figure 6 is Figure 1 a schematic structural view of the ball seat in

[0022] In the figure: upper expansion head 1; upper expansion tube 2, rubber sealing ring 2-1, metal sealing ring 2-2; upper outer cylinder 3, upper locking ring 4, middle locking ring 5; inner cylinder 6, first locking ball groove 6-1, suspension step 6-2, pawl 6-3; lower outer cylinder 7, pressure ball 8; ball seat 9, second locking ball groove 9-1; lower locking ring 10, locking ball 11, locking cylinder 12, lower expansion cylinder 13, lower expansion head 14, limit head 15, anti-loosening ring 16, connecting inner tube 17, connecting outer cylinder 18. Detailed implementation manner

[0023] The attached drawings are only for reference and illustration purposes, and are not intended to limit the protection scope of the present invention. The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0024] In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, and are not used to limit the present invention.

[0025] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present invention and simplifying the description, 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 therefore should not be construed as a limitation of the present invention. In addition, in the description of the present invention, the meaning of "a plurality" is two or more, unless otherwise specifically defined.

[0026] See Figure 1 - Figure 6 , a sealing working barrel hanging device for old wells, provided with an external releasing string and an internal retrievable string, wherein: the external releasing string includes an upper expansion head 1 and a lower expansion head 14, an upper expansion tube 2 and a lower expansion tube 13, and an upper outer cylinder 3 and a lower outer cylinder 7, and the upper expansion tube 2, the upper outer cylinder 3, the lower outer cylinder 7 and the lower expansion tube 13 are connected in sequence from top to bottom; the upper locking ring 4, the middle locking ring 5 and the lower locking ring 10 are respectively clamped and installed between the upper expansion cylinder 2 and the upper outer cylinder 3, between the upper outer cylinder 3 and the lower outer cylinder 7, and between the lower outer cylinder 7 and the lower expansion cylinder 13; The middle locking ring 5 is processed with threads inside and can be threadedly connected to the sealing insertion tube in the combined sealing device; the upper expansion head 1 and the lower expansion head 14 are respectively inserted from the other ends of the upper expansion tube 2 and the lower expansion tube 13 and cooperate with the upper locking ring 4 and the lower locking ring 10 respectively; The internal retrievable pipe string includes an inner cylinder 6, a locking cylinder 12 and a ball seat 9. The upper part of the inner cylinder 6 is provided with a booster connection thread, the lower part is provided with a pawl 6-3, and the inner cavity is provided with a first locking ball groove 6-1 and a suspension step 6-2. The inner cylinder 6 can be threadedly connected to the booster through the booster connection thread; The ball seat 9 installed in the upper part of the locking cylinder 12 is provided with a second locking ball groove 9-1. The ball seat 9 and the inner cylinder 6 are connected by shear pins; when the limiting head 15 connected to the lower part of the locking cylinder 12 is constrained in the pawl 6-3 of the inner cylinder 6, the locking ball 11 in the barrel wall of the locking cylinder 12 can fix the locking cylinder 12 and the inner cylinder 6 together through the first locking ball groove 6-1; when the pressure ball 8 is put in and the ball seat 9 is knocked off, the ball seat 9 releases the locking ball 11 through the second locking ball groove 9-1 during the falling process and can move down together with the locking cylinder 12 and be suspended on the suspension step 6-2 of the inner cylinder 6.

[0027] The working principle of the device of the present invention is that when going into the well, the inner cylinder 6 in this tool is connected with the connecting inner pipe 17 in the booster connected to the lower end of the service string and lowered into the predetermined position in the well.

[0028] During operation, pressure is applied from the ground, and the liquid enters the inner cavity of the inner cylinder 6 in the present invention through the oil pipe, and the pressure ball 8 is pushed against the ball seat 9. After the booster increases the pressure, the lower end of the connecting outer cylinder 18 in the upper booster applies force downward from above the upper expansion head 1, so that the upper expansion head 1 and the lower expansion head 14 are simultaneously squeezed inward. At the same time, the connecting inner pipe 17 pulls the inner cylinder 6, causing relative movement between the internal retrievable pipe string and the external releasing pipe string in the present invention, and expanding and fixing the upper expansion head 1 and the lower expansion head 14 on the external casing.

[0029] When the pressure rises to the predetermined working pressure, the shear pin between the inner cylinder 6 and the ball seat 9 is cut off, the ball seat 9 moves down to release the locking ball 11, and the ball seat 9 moves down and presses on the locking cylinder 12, causing the locking cylinder 12 to move down together. During the downward movement of the locking cylinder 12 and the limiting head 15, the limiting head 15 disengages from the pawl 6-3 at the lower part of the inner cylinder 6, and the pawl 6-3 loses internal support. At this time, the internal retrievable pipe string can be retrieved. The pawl 6-3 is a claw-shaped body formed by downwardly cutting a through slot in the lower body of the inner cylinder 6, and has elasticity, can be expanded and contracted.

[0030] The service string is lifted to retrieve the internal retrievable pipe string in the present invention, realizing the release of the external releasing pipe string in the present invention. The external releasing pipe string is permanently retained on the inner wall of the wellbore of the old well as a sealing working cylinder, and can be connected with the sealing insertion tube lowered into the well, effectively solving the defect that the combined sealing device cannot be used in old wells.

[0031] On the basis of the above-mentioned first embodiment, the present invention also has the following embodiments: A preferred embodiment: The inner circles of the upper locking ring 4 and the lower locking ring 10 are both processed with knuckle threads and can be respectively matched with the knuckle threads on the outer circles of the upper expansion head 1 and the lower expansion head 14, which can prevent the upper expansion head 1 and the lower expansion head 14 from loosening.

[0032] A preferred embodiment: The middle locking ring 5 is a split ring provided with an axial notch. The notch provided axially is an inclined notch or a vertical notch, and the inclined angle is set between 1 degree and 89 degrees; the outer diameter of the middle locking ring 5 in the natural state is smaller than the inner diameter of the tube section of the upper outer cylinder 3 where it is located; the inner circle of the middle locking ring 5 is processed with threads that can be connected to the sealing insertion tube in the combined sealing device, and the top is processed with torque transmission splines. The torque transmission splines at the top of the middle locking ring 5 can be matched with the torque transmission splines in the upper outer cylinder 3.

[0033] A preferred embodiment: Both the upper expansion head 1 and the lower expansion head 14 are of a cylindrical structure, and their outer circles are non-uniform diameter outer circles. There is a tension cone surface between the large-diameter outer circle section and the small-diameter outer circle section of the upper expansion head 1, and knuckle threads that can cooperate with the upper locking ring 4 are provided in the small-diameter outer circle section; a pawl claw end embedding groove is provided in the inner circle at the lower end of the lower expansion head 14. An expansion tube mating step and tension steps above the second level are provided on the outer circle of the lower part of the lower expansion head 14. There is a tension cone surface between the expansion tube mating step and the tension steps. The tension cone surfaces in the outer circles of the upper expansion head 1 and the lower expansion head 14 are arranged facing each other; knuckle threads that can cooperate with the lower locking ring 10 are provided on the outer circle of the upper part of the lower expansion head 14.

[0034] A preferred embodiment: Both the upper expansion tube 2 and the lower expansion tube 13 are of non-uniform diameter cylindrical structures, and tension mating cone surfaces are provided in the inner circles of the upper expansion tube 2 and the lower expansion tube 13; the tension mating cone surfaces in the upper expansion tube 2 and the lower expansion tube 13 are arranged back to back and can be respectively matched with the tension cone surfaces in the upper expansion head 1 and the lower expansion head 14. The knuckle threads in the upper expansion tube 2 and the lower expansion tube 13 can be respectively matched with the knuckle threads in the upper locking ring 4 and the lower locking ring 10.

[0035] A preferred embodiment: Upper outer cylinder limiting steps and lower outer cylinder limiting steps are respectively provided on the outer circles of the upper expansion tube 2 and the lower expansion tube 13; on the outer circle of the upper expansion tube 2 above the upper outer cylinder limiting step, a metal sealing ring groove 2-2, a rubber sealing ring groove 2-1 and an expanded diameter strain groove are successively arranged from bottom to top, and a metal sealing ring and a rubber sealing ring are respectively installed in the metal sealing ring groove 2-2 and the rubber sealing ring groove 2-1; on the outer circle of the lower expansion tube 13 below the lower outer cylinder limiting step, a metal sealing ring groove, a rubber sealing ring groove and an expanded diameter strain groove are also successively arranged from top to bottom, and a metal sealing ring and a rubber sealing ring are respectively installed in the metal sealing ring groove and the rubber sealing ring groove; the groove depth of the expanded diameter strain groove in the outer circles of the upper expansion tube 2 and the lower expansion tube 13 is set between 2 mm and 5 mm to meet the variable diameter requirements of the upward movement of the upper expansion tube 2 and the downward movement of the lower expansion tube 13.

[0036] A preferred embodiment: Refer to Figure 1 and Figure 3 , the upper outer cylinder 3 is a non-uniform diameter cylinder body with internal threads provided at both ends and can be threadedly connected to the upper expansion tube 2 and the lower outer cylinder 7 respectively; on the inner circle of the upper outer cylinder 3, a upper lock ring installation cavity, a lock ring separating platform and a middle lock ring installation cavity are also successively arranged from top to bottom, and a torque transmission spline is provided in the lower part body of the lock ring separating platform. The torque transmission spline in the body of the lock ring separating platform can cooperate with the torque transmission spline at the top of the middle lock ring 5, and after cooperation, the middle lock ring 5 is exactly located in the middle lock ring installation cavity in the upper outer cylinder 3. The cooperation between the middle lock ring 5 and the torque transmission spline in the upper outer cylinder 3 can complete the torque transmission between the sealing insertion tube in the combined sealing device and the external releasing pipe string serving as the sealing working barrel during the releasing process in the later application.

[0037] A preferred embodiment: The lower outer cylinder 7 is a non-uniform diameter cylinder structure, with external threads and internal threads processed at the upper and lower ends respectively. The upper inner cavity of the lower outer cylinder 7 is a conical cavity, and a lower lock ring installation cavity is above the upper end internal thread section; the smallest inner circular surface in the lower outer cylinder 7 is a sealing surface.

[0038] A preferred embodiment: The ball seat 9 is a non-uniform diameter cylinder body, the upper inner cavity of the ball seat 9 is a conical cavity and the smallest inner diameter is smaller than the outer diameter of the pressure ball 8; a sealing ring groove and a shear pin hole or shear pin groove are provided on the upper outer circle of the ball seat 9, and the lock ball groove two 9-1 is arranged in the lower outer circle of the ball seat 9; when the ball seat 9 is connected to the inner cylinder 6 by shear pins, the lock ball groove two 9-1 is located above the lock ball 11.

[0039] A preferred embodiment: The lock cylinder 12 is a non-uniform diameter cylinder body, the upper inner cavity of the lock cylinder 12 is a ball seat adaptation cavity and a lock ball assembly hole is provided in the barrel wall of the upper inner cavity; a sealing ring groove is provided on the outer circle of the lock cylinder 12 below the lock ball assembly hole, and the upper outer circle of the lock cylinder 12 can be installed in the inner cylinder 6 and can be suspended on the suspension step 6-2 of the inner cylinder 6.

[0040] A preferred embodiment: The outer circumference of the lower part of the lock cylinder 12 is provided with an external thread and can be threadedly connected to the limit head 15. An anti-loosening ring 16 is also threadedly connected below the limit head 15. The limit head 15 is a non-uniform diameter cylinder and is provided with an internal thread. The outer conical surface between the large diameter section and the small diameter section of the outer circumference of the limit head 15 conforms to the inner wall taper of the pawl 6-3.

[0041] A construction method for a suspension device of a sealing working cylinder for old wells includes the following steps: A. Assemble the inner cylinder 6 in the suspension device of the sealing working cylinder and the connecting inner pipe 17 in the booster connected to the lower end of the service string and lower them into a predetermined position in the well. B. After reaching the predetermined position in the well, apply pressure from the ground to preliminarily anchor the suspension device of the sealing working cylinder at the predetermined position in the well. During this process, apply pressure from the ground, and the liquid enters the inner cavity of the inner cylinder 6 in the present invention through the tubing in the service string, and the pressure ball 8 is pushed against the ball seat 9. C. Increase the pressure of the booster to anchor the external release string in the suspension device of the sealing working cylinder at the predetermined position in the well. During this process, after the booster increases the pressure, the lower end of the connecting outer cylinder 18 in the upper booster applies force downward from above the upper expansion head 1, so that the upper expansion head 1 and the lower expansion head 14 are simultaneously squeezed inward. At the same time, the connecting inner pipe 17 pulls the inner cylinder 6, causing relative movement between the internal retrievable string and the external release string in the present invention, and expanding the upper expansion head 1 and the lower expansion head 14 against the external casing. D. Retrieve the internal retrievable string to achieve the release of the external release string, and permanently leave the external release string in the well as the sealing working cylinder of the combined sealing device.

[0042] In process D, when the ground pressure increases to the predetermined working pressure, the shear pin between the inner cylinder 6 and the ball seat 9 is cut off, the ball seat 9 moves downward to release the lock ball 11, and after the ball seat 9 moves downward, it abuts against the lock cylinder 12 and causes the lock cylinder 12 to move downward together. During the downward movement of the lock cylinder 12 and the limit head 15, the limit head 15 disengages from the pawl 6-3 at the lower part of the inner cylinder 6, and the pawl 6-3 loses support.

[0043] Lift the service string to retrieve the internal retrievable string in the present invention, achieve the release of the external release string in the present invention, and the external release string remains permanently in the inner wall of the wellbore of the old well as the sealing working cylinder, which can be connected in cooperation with the sealing insertion pipe lowered into the well, effectively solving the defect that the combined sealing device cannot be used in old wells, being able to effectively reduce the production cost of old wells, significantly improving the economic benefits of old wells, and having remarkable use effects and application values.

[0044] The embodiments described above are merely exemplary embodiments, but the present invention is not limited to these embodiments. Those skilled in the art can make modifications without departing from the spirit and inspiration of the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the creative spirit and creative concept of the present invention shall be included within the protection scope of the present invention. Therefore, the protection scope is not limited to the foregoing description.

Claims

1. A sealing working barrel suspension device for old wells, Characterized in that: It is provided with an external releasing pipe string and an internal retrievable pipe string; the external releasing pipe string includes an upper expansion head (1) and a lower expansion head (14), an upper expansion pipe (2) and a lower expansion pipe (13), and an upper outer cylinder (3) and a lower outer cylinder (7). The upper expansion pipe (2), the upper outer cylinder (3), the lower outer cylinder (7) and the lower expansion pipe (13) are connected in sequence from top to bottom; an upper locking ring (4), a middle locking ring (5) and a lower locking ring (10) are respectively clamped and installed between the upper expansion cylinder (2) and the upper outer cylinder (3), between the upper outer cylinder (3) and the lower outer cylinder (7), and between the lower outer cylinder (7) and the lower expansion cylinder (13); the middle locking ring (5) is internally machined with threads and can be threadedly connected to the sealing insertion pipe in the combined sealing device; the upper expansion head (1) and the lower expansion head (14) are respectively inserted from the other ends of the upper expansion pipe (2) and the lower expansion pipe (13) and cooperate with the upper locking ring (4) and the lower locking ring (10) respectively; the internal retrievable pipe string includes an inner cylinder (6), a locking cylinder (12) and a ball seat (9). The upper part of the inner cylinder (6) is provided with a booster connection thread, the lower part is provided with a pawl (6-3), and the inner cavity is provided with a locking ball groove one (6-1) and a suspension step (6-2). The inner cylinder (6) can be threadedly connected to the booster through the booster connection thread; the ball seat (9) installed in the upper part of the locking cylinder (12) is provided with a locking ball groove two (9-1), and the ball seat (9) is connected to the inner cylinder (6) by a shear pin; when the limit head (15) connected to the lower part of the locking cylinder (12) is constrained in the pawl (6-3) of the inner cylinder (6), the locking ball (11) in the wall of the locking cylinder (12) can fix the locking cylinder (12) and the inner cylinder (6) together through the locking ball groove one (6-1); when the pressure ball (8) is put in and the ball seat (9) is knocked off, the ball seat (9) releases the locking ball (11) through the locking ball groove two (9-1) during the falling process and can move down and hang on the suspension step (6-2) of the inner cylinder (6) together with the locking cylinder (12).

2. A sealing working barrel suspension device for old wells according to claim 1, Characterized in that, The inner circles of the upper locking ring (4) and the lower locking ring (10) are both machined with serrations and can respectively cooperate with the serrations on the outer circles of the upper expansion head (1) and the lower expansion head (14).

3. A sealing working barrel suspension device for old wells according to claim 2, Characterized in that, The middle locking ring (5) is a split ring provided with an axial notch. The notch provided axially is an oblique notch or a vertical notch, and the oblique angle is set between 1 degree and 89 degrees; the outer diameter of the middle locking ring (5) in the natural state is smaller than the inner diameter of the upper outer cylinder (3) pipe section where it is located; the inner circle of the middle locking ring (5) is machined with threads capable of connecting to the sealing insertion pipe in the combined sealing device, and the top is machined with torque transmission splines. The torque transmission splines at the top of the middle locking ring (5) can cooperate with the torque transmission splines in the upper outer cylinder (3).

4. A sealing working barrel suspension device for old wells according to claim 2, Characterized in that, The upper expansion head (1) and the lower expansion head (14) are both of cylindrical structures, and their outer circles are non-uniform-diameter outer circles. Between the large-diameter outer circle section and the small-diameter outer circle section of the upper expansion head (1) is a tensioning conical surface, and in the small-diameter outer circle section, there are bayonet joints that can cooperate with the upper locking ring (4); in the inner circle at the lower end of the lower expansion head (14), there is a pawl tip embedding groove, and on the outer circle of the lower part of the lower expansion head (14), there are expansion tube mating steps and tensioning steps of two or more levels. Between the expansion tube mating steps and the tensioning steps is a tensioning conical surface. The tensioning conical surfaces in the outer circles of the upper expansion head (1) and the lower expansion head (14) are arranged facing each other; on the outer circle of the upper part of the lower expansion head (14), there are bayonet joints that can cooperate with the lower locking ring (10).

5. A sealing working barrel hanging device for old wells as described in claim 4, characterized in that, the upper expansion tube (2) and the lower expansion tube (13) are both of non-uniform-diameter cylindrical structures, and tensioning mating conical surfaces are provided in the inner circles of the upper expansion tube (2) and the lower expansion tube (13); the tensioning mating conical surfaces in the upper expansion tube (2) and the lower expansion tube (13) are arranged back to back and can respectively cooperate with the tensioning conical surfaces in the upper expansion head (1) and the lower expansion head (14), and the bayonet joints in the upper expansion tube (2) and the lower expansion tube (13) can respectively cooperate with the bayonet joints in the upper locking ring (4) and the lower locking ring (10).

6. A sealing working barrel hanging device for old wells as described in claim 5, characterized in that, outer circles of the upper expansion tube (2) and the lower expansion tube (13) are respectively provided with an upper outer barrel limiting step and a lower outer barrel limiting step; above the upper outer barrel limiting step, on the outer circle of the upper expansion tube (2), a metal sealing ring groove (2-2), a rubber sealing ring groove (2-1), and a diameter-expanding strain groove are sequentially arranged from bottom to top. A metal sealing ring and a rubber sealing ring are respectively installed in the metal sealing ring groove (2-2) and the rubber sealing ring groove (2-1); below the lower outer barrel limiting step, on the outer circle of the lower expansion tube (13), a metal sealing ring groove, a rubber sealing ring groove, and a diameter-expanding strain groove are also sequentially arranged from top to bottom, and a metal sealing ring and a rubber sealing ring are respectively installed in the metal sealing ring groove and the rubber sealing ring groove; the groove depth of the diameter-expanding strain groove in the outer circles of the upper expansion tube (2) and the lower expansion tube (13) is set between 2 mm and 5 mm.

7. A sealing working barrel hanging device for old wells as described in claim 6, characterized in that, the upper outer barrel (3) is a non-uniform-diameter cylinder body and is provided with internal threads at both ends and can be respectively thread-connected with the upper expansion tube (2) and the lower outer barrel (7); in the inner circle of the upper outer barrel (3), an upper locking ring installation cavity, a locking ring separating platform, and a middle locking ring installation cavity are also provided from top to bottom. In the lower part of the body of the locking ring separating platform, there is a torque transmission spline, and the torque transmission spline in the body of the locking ring separating platform can cooperate with the torque transmission spline at the top of the middle locking ring (5). After cooperation, the middle locking ring (5) is exactly located in the middle locking ring installation cavity in the upper outer barrel (3).

8. A sealing working barrel hanging device for old wells as described in claim 7, characterized in that, The lower outer cylinder (7) is a non-uniform-diameter cylinder structure, with external threads and internal threads machined at the upper and lower ends respectively. The upper inner cavity of the lower outer cylinder (7) is a conical cavity, and above the lower internal thread section is the lower lock ring installation cavity; the smallest inner circular surface in the lower outer cylinder (7) is the sealing surface.

9. A sealing working barrel hanging device for old wells as described in claim 7, characterized in that the ball seat (9) is a non-uniform-diameter cylinder, the upper inner cavity of the ball seat (9) is a conical cavity and the smallest inner diameter is smaller than the outer diameter of the pressure ball (8); a sealing ring groove and shear pin holes or shear pin grooves are provided on the upper outer circle of the ball seat (9), and the second locking ball groove (9-1) is arranged in the lower outer circle of the ball seat (9); when the ball seat (9) is connected to the inner cylinder (6) by shear pins, the second locking ball groove (9-1) is located above the locking ball (11).

10. A sealing working barrel hanging device for old wells as described in claim 9, characterized in that the locking cylinder (12) is a non-uniform-diameter cylinder, the upper inner cavity of the locking cylinder (12) is a ball seat adaptation cavity and locking ball assembly holes are provided in the barrel wall of the upper inner cavity; a sealing ring groove is provided on the outer circle of the locking cylinder (12) below the locking ball assembly holes, and the upper outer circle of the locking cylinder (12) can be installed in the inner cylinder (6) and can be suspended on the suspension step (6-2) of the inner cylinder (6).

11. A sealing working barrel hanging device for old wells as described in claim 10, characterized in that the lower outer circle of the locking cylinder (12) is provided with external threads and can be threadedly connected to the limit head (15), and a lock prevention ring (16) is also threadedly connected below the limit head (15); the limit head (15) is a non-uniform-diameter cylinder and is provided with internal threads, and the outer conical surface that can conform to the inner wall taper of the ratchet pawl (6-3) is between the large diameter section and the small diameter section of the outer circle of the limit head (15).

12. A construction method for a sealing working barrel hanging device for old wells according to any one of claims 1-11, characterized in that it includes the following steps: A. Assemble the inner cylinder (6) in the sealing working barrel hanging device with the connecting inner pipe (17) in the booster connected to the lower end of the service string and lower it to a predetermined position in the well; B. After reaching the predetermined position in the well, apply pressure from the ground to preliminarily anchor the sealing working barrel hanging device at the predetermined position in the well; C. Increase the pressure of the booster to anchor the external release string in the sealing working barrel hanging device at the predetermined position in the well; D. Lift out the internally retrievable string to achieve the release of the external release string, and permanently leave the external release string in the well to be used as the sealing working barrel of the combined sealing device.

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