Packer unsealing tool

Abstract

The invention belongs to the field of multi-stage packers, and particularly relates to a packer unsealing tool. In order to solve the technical problems that multiple packers with different strokes need to be used in a multi-stage layered tubular column structure in the prior art, the manufacturing cost of the packers is high, and the packers are inconvenient to use, the invention provides the packer unsealing tool. The packer unsealing tool comprises a central pipe and an outer pipe which have a certain relative movement stroke, the central pipe and the outer pipe are fixedly connected through a locking mechanism, and the locking mechanism can be unlocked after the adjacent packers are completely sealed. In the layered tubular column structure, after the packers are set, the packer unsealing tool is unlocked, and the unsealing stroke is provided for the upper-stage packer through the packer unsealing tool, so that step-by-step unsealing of the packers is realized, only one type of packer can be adopted, the use is convenient, and the cost is relatively low.

Description

Technical Field

[0001] The present invention belongs to the field of multi-stage packers, and particularly relates to a packer releasing tool. Background Art

[0002] During the process of oil extraction, packers are commonly used devices. Among them, the lifting-release packer is a device connected to the tubing, which can be seated in the casing by pressure and released by lifting.

[0003] Under the working conditions of relatively complex formation conditions, a multi-stage stratified water injection process needs to be adopted to inject water into different formations separately, so as to improve the oil production efficiency. The Chinese utility model patent with the authorization publication number CN210033391U and the authorization publication date of February 7, 2020 discloses a multi-stage stratified water injection string, which includes water distributors at all levels connected by tubing. A lifting-release packer is connected between adjacent two-stage water distributors. Among the packers at adjacent two levels, the release stroke of the upper-stage packer is less than that of the lower-stage packer. Specifically, the lifting-release packer is the commonly used Y341 type packer for water wells. The packer includes a central pipe, an outer pipe, a setting mechanism and a corresponding releasing mechanism. Through the setting mechanism, the packer can be set when the pressure in the central pipe meets the setting pressure; when the central pipe is lifted, the releasing mechanism can cut the releasing shear pins fixedly connecting the central pipe and the outer pipe, so as to realize the release of the packer. Of course, the lifting-release packer can also be the Y211 type packer.

[0004] Since the release stroke of the upper-stage packer is less than that of the lower-stage packer, when the upper-stage packer is released, the force of the lower-stage packer is not transmitted to the upper-stage packer, and the release forces of the packers at all levels do not superimpose, so that the step-by-step release of the packers at all levels can be conveniently realized.

[0005] However, in the above-mentioned utility model patent, packers with various different release strokes are required. If it is a two-stage stratified string structure, two packers with different strokes are required; if it is a three-stage stratified string structure, three packers with different strokes are required; if it is a five-stage stratified string structure, five packers with different strokes are required. During the on-site oil production process, the formation structures in different places may be different, resulting in different numbers of stages of the stratified string structures to be adopted, and thus different numbers of packers with different strokes need to be used according to the actual situation. As a result, there are many types of packers on site, which requires a variety of molds during manufacturing, resulting in high costs, and it is inconvenient to use because it is necessary to distinguish the release strokes of different packers on site.

[0006] At the same time, in the multi-stage stratified water injection string in the above-mentioned utility model patent, the tubing will creep under the influence of casing pressure and oil pressure, resulting in deformation of the tubing. Summary of the Invention

[0007] The object of the present invention is to provide a packer release tool to solve the technical problems in the prior art that in a multi-stage stratified pipe string structure, multiple packers with different strokes are required, resulting in a relatively high manufacturing cost of the packers, and it is necessary to distinguish the strokes of different packers during on-site use, which is inconvenient for use.

[0008] To achieve the above object, the technical solution of the packer release tool provided by the present invention is as follows:

[0009] A packer release tool includes a central tube for connecting with an upper-stage upward-pulling release type packer and an outer tube for connecting with a lower-stage upward-pulling release type packer. An inner stop portion is provided on the central tube, which can move synchronously with the central tube and is used for axially stopping and cooperating with the outer tube after the central tube is pulled up by a certain stroke, so that the central tube can drive the outer tube to move upward; the central tube and the outer tube are fixedly connected by a locking mechanism that is unlocked by using the pressure inside the central tube, and the unlocking pressure corresponding to the locking mechanism satisfies: the unlocking pressure is greater than the setting pressures of the corresponding upper-stage packer and lower-stage packer.

[0010] Furthermore, an unlocking space is provided between the central tube and the outer tube. An unlocking liquid inlet hole communicating the unlocking space and the central tube is provided on the central tube. The central tube and the outer tube are directly or indirectly fixedly connected by a fixing member, and a movable member for shearing the fixing member is further provided in the unlocking space; the movable member, the unlocking space, the unlocking liquid inlet hole and the fixing member together constitute the locking mechanism.

[0011] Furthermore, the fixing member passes through the movable member and the outer tube, the fixing member is closely attached to the central tube, and an elastic member sleeved on the movable member is provided between the fixing member and the outer tube; an accommodating groove for accommodating the elastic member is provided on the outer tube; the elastic member has a locking state in which it axially stops and cooperates with both the central tube and the accommodating groove before the fixing member is sheared, so that the central tube and the outer tube are indirectly fixedly connected by the fixing member, and the elastic member also has an unlocking state in which it disengages from the accommodating groove after the fixing member is sheared, so that relative axial movement can occur between the central tube and the outer tube.

[0012] Furthermore, the working area of the movable member corresponding to the pressure inside the central tube is smaller than the working area of the setting mechanism of the corresponding packer corresponding to the pressure inside the central tube.

[0013] Furthermore, the inner stop portion includes a first inner stop portion. The first inner stop portion axially seals and cooperates with both the outer tube and the central tube, and a first outer stop portion corresponding to the first inner stop portion and capable of moving synchronously with the outer tube is provided on the outer tube. The first outer stop portion axially seals and cooperates with both the outer tube and the central tube. A first accommodating space communicating with the outside of the outer tube is formed among the first inner stop portion, the central tube, the outer tube and the first outer stop portion.

[0014] Furthermore, the projected area in the axial direction of the contact surface of the first outer stop portion for contacting the liquid in the first accommodation space is equal to the projected area in the axial direction of the sealing rubber cylinder of the next-stage packer.

[0015] Furthermore, the inner stop portion of the packer release tool further includes a second inner stop portion. The second inner stop portion, the central tube and the outer tube are all in sealing fit along the axial direction. And a second outer stop portion that can move synchronously with the outer tube and corresponds to the second inner stop portion is provided on the outer tube. The second outer stop portion, the central tube and the outer tube are all in sealing fit along the axial direction. A second accommodation space communicating with the inside of the central tube is formed among the second inner stop portion, the central tube, the outer tube and the second outer stop portion.

[0016] Furthermore, the projected area in the axial direction of the contact surface of the second outer stop portion for contacting the liquid in the second accommodation space is equal to the projected area in the axial direction of the contact surface between the bottom sealing structure of the stratified pipe string structure and the liquid in the stratified pipe string structure.

[0017] Furthermore, the central tube is fixedly connected in sequence by an upper joint, a first connecting tube and a second connecting tube. An unlocking space is formed between the outer tube, the upper joint and the upper part of the first connecting tube; a first accommodation space or a second accommodation space is formed among the lower part of the first connecting tube, the upper part of the second connecting tube and the outer tube. The upper part of the second connecting tube constitutes the inner stop portion; an inner stop portion is fixedly connected to the lower part of the second connecting tube. A second accommodation space or a first accommodation space is formed among the inner stop portion, the first connecting tube and the outer tube.

[0018] The beneficial effects of the packer release tool of the present invention are as follows: The present invention is a pioneering invention. The central tube can be connected to the upper-stage upward-release packer, and the outer tube can be connected to the lower-stage upward-release packer; the unlocking pressure is greater than the setting pressures of the corresponding upper-stage and lower-stage packers. In actual use, first, pressure is applied to the central tube for setting. After the upper-stage and lower-stage packers corresponding to the packer release tool are both set, the pressure in the central tube is continuously increased. When the pressure reaches the unlocking pressure, the central tube and the outer tube are unlocked. At this time, since both the upper-stage and lower-stage packers are already set, relative movement does not occur between the central tube and the outer tube of the packer release tool; after the central tube and the outer tube are unlocked, when the packer is lifted to be released, the force of the upper-stage packer is only transmitted to the central tube of the corresponding packer release tool. Since the central tube and the outer tube of the packer release tool are already unlocked, only the release shear pins of the upper-stage packer need to be cut when lifting and releasing the upper-stage packer. The release forces of each stage of packers do not stack, and the step-by-step release of each stage of packers can be conveniently achieved. After the upper-stage packer is released, after the central tube of the packer release tool moves upward a certain stroke, the inner stop portion can cooperate with the outer tube stop, thereby driving the outer tube to move upward, ensuring that the force can be transmitted to the lower-stage packer to realize the upward release of the lower-stage packer. The present invention provides a separately provided packer release tool. In a layered pipe string structure, there is no need to set packers with various different release strokes. Only a packer release tool needs to be set between adjacent two-stage packers, so that the packers in the layered pipe string structure can be completely the same. Only one type of packer needs to be manufactured during manufacturing, which can effectively reduce costs, and there is no need to distinguish the models of the packers during use, which is convenient for use. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 FIG. is a schematic structural diagram of the embodiment of the packer release tool in the present invention for the case where the oil pressure is greater than the casing pressure in a three-stage layered pipe string structure;

[0020] Figure 2 is Figure 1 a schematic structural diagram of the case where the casing pressure is greater than the oil pressure in;

[0021] Figure 3 is Figure 1 a schematic structural diagram of the step-by-step release of the packer in;

[0022] Figure 4 is Figure 1 a schematic structural diagram of the packer release tool in;

[0023] Figure 5 is Figure 4 an enlarged structural view of part A when the packer release tool in is not unlocked;

[0024] Figure 6 The enlarged structural view of part A when the packer release tool in Figure 4 is just unlocked;

[0025] Figure 7 The enlarged structural view of part A after the central tube of the packer release tool in Figure 4 has moved upward a certain distance;

[0026] Figure 8 The enlarged structural view of the upper part of the packer release tool in Figure 4 ;

[0027] Figure 9 The enlarged structural view of the lower part of the packer release tool in Figure 4 ;

[0028] Explanation of reference numerals:

[0029] 1. Stratified string structure; 2. Water distributor; 3. Packer; 4. Packer release tool; 5. Bottom sealing structure; 6. Injection layer; 7. Casing; 41. Central tube; 4101. Upper joint; 4102. First connecting pipe; 4103. Second connecting pipe; 42. Outer tube; 4201. Lower joint; 4202. Outer cylinder; 4203. Accommodating groove; 43. Unlocking piston; 44. Sealing ring; 45. Unlocking liquid inlet hole; 46. Unlocking shear pin; 471. First outer stop portion; 472. Second outer stop portion; 48. Casing pressure balance liquid inlet hole; 491. First inner stop portion; 492. Second inner stop portion; 410. Oil pressure balance liquid inlet hole; 411. Circlip. Detailed implementation manners

[0030] The present invention will be further described in detail below with reference to the embodiments.

[0031] Specific embodiments of the packer release tool provided by the present invention:

[0032] The purpose of the present invention is to provide a packer release tool. By means of the central tube and the outer tube respectively connected to two adjacent upward-release packers, and using the stroke existing between the central tube and the outer tube, when the upper-stage packer is lifted to be released, the force can be ensured not to be transmitted to the lower-stage packer, thereby avoiding the superposition of the release forces of each stage of the packer and realizing the step-by-step release of the packer. At the same time, when applied to the stratified string structure, only the same type of packer can be used, which can effectively reduce the manufacturing cost of the packer, and there is no need to distinguish the models of the packers during use, which is convenient for use.

[0033] The packer release tool in this embodiment will be introduced in detail below in combination with the stratified string structure:

[0034] As shown in Figures 1 - 9As shown, as a specific embodiment, the layered string structure 1 includes at least two pull-up and release packers 3. A packer release tool 4 is provided between adjacent packers 3. The packer release tool 4 includes a central tube 41 connected to the upper-level packer 3 and an outer tube 42 connected to the lower-level packer 3. An inner stop portion is provided on the central tube 41, which can move synchronously with the central tube and is used for axially stop-fitting with the outer tube 42 after the central tube 41 is pulled up by a certain stroke, so that the central tube 41 can drive the outer tube 42 to move upward. The central tube 41 and the outer tube 42 are fixedly connected by a locking mechanism unlocked by using the pressure inside the central tube 41, and the unlocking pressure corresponding to the locking mechanism satisfies: the unlocking pressure is greater than the setting pressure of the corresponding upper-level packer 3 and lower-level packer 3.

[0035] Specifically, as Figures 1 - 3 shown, in this specific embodiment, taking a three-stage and four-layer layered string as an example for introduction, the layered string structure 1 includes water distributors 2 corresponding to four injection layers 6 respectively. Pull-up and release packers 3 are provided between adjacent water distributors 2. Packer release tools 4 are provided between adjacent packers 3. A bottom sealing structure 5 (including structures such as a check valve, a ball seat, and a plug) is provided at the bottom of the layered string structure 1. In this specific embodiment, except for the packer release tool 4, the rest of the structures are prior arts and will not be elaborated here in detail.

[0036] Meanwhile, in other specific embodiments, the layered string structure 1 can also be a three-stage and three-layer layered string (including three packers 3), or a two-stage and three-layer layered string (including two packers 3), etc. In this embodiment, the specific structure of the layered string structure 1 is not limited as long as the layered string structure 1 includes more than two packers 3.

[0037] It can be connected to the upper-stage pull-up and release packer 3 through the central pipe 41, and can be connected to the lower-stage pull-up and release packer 3 through the outer pipe 42; the unlocking pressure is greater than the setting pressures of the corresponding upper-stage packer 3 and lower-stage packer 3. In actual use, first, pressure is applied to the central pipe 41 for setting. After the upper-stage packer 3 and lower-stage packer 3 corresponding to the packer release tool 4 are both set, the pressure in the central pipe 41 is continuously increased. When the pressure reaches the unlocking pressure, the central pipe 41 and the outer pipe 42 are unlocked. At this time, since both the upper-stage packer 3 and the lower-stage packer 3 have been set, relative movement will not occur between the central pipe 41 and the outer pipe 42 of the packer release tool 4; after the central pipe 41 and the outer pipe 42 are unlocked, when the packer 3 is pulled up for release, the force of the upper-stage packer 3 is only transmitted to the central pipe 41 of the corresponding packer release tool 4. Since the central pipe 41 and the outer pipe 42 of the packer release tool 4 have been unlocked, only the upper-stage packer 3 needs to be released when pulling up and releasing the upper-stage packer 3. The release forces of each stage of the packer 3 do not superimpose, and the step-by-step release of each stage of the packer 3 can be conveniently achieved. After the upper-stage packer 3 is released, after the central pipe 41 of the packer release tool 4 moves upward by a certain stroke, the inner stop portion can cooperate with the outer pipe 42 in a stop manner, thereby driving the outer pipe 42 to move upward, ensuring that the force can be transmitted to the lower-stage packer 3 to realize the pull-up and release of the lower-stage packer 3.

[0038] In this embodiment, through the separately provided packer release tool 4, in the layered pipe string structure 1, there is no need to set packers 3 with various different release strokes. Only the packer release tool 4 needs to be set between two adjacent stages of packers 3, so that the packers 3 in the layered pipe string structure 1 can be exactly the same. Only one type of packer 3 needs to be manufactured during manufacturing, which can effectively reduce costs, and on-site workers do not need to distinguish the models of the packers 3 during use, which is convenient for use.

[0039] As Figures 4 - 7 shown, in order to facilitate the unlocking between the central pipe 41 and the outer pipe 42, as a specific implementation manner, an unlocking space is provided between the central pipe 41 and the outer pipe 42. The central pipe 41 is provided with an unlocking liquid inlet hole 45 communicating the unlocking space and the central pipe 41. The central pipe 41 and the outer pipe 42 are directly or indirectly fixedly connected through a fixing member. An active member for shearing the fixing member is also provided in the unlocking space. The unlocking pressure corresponding to the active member shearing the fixing member satisfies: the unlocking pressure is greater than the setting pressures of the corresponding upper-stage packer 3 and lower-stage packer 3; the active member, the unlocking space, the unlocking liquid inlet hole 45 and the fixing member together constitute the locking mechanism.

[0040] Specifically, the fixing member is the unlocking shear pin 46, and the moving member is the unlocking piston 43. The unlocking shear pin 46 passes through the unlocking piston 43 and the outer tube 42. When the unlocking pressure is reached, the unlocking piston 43 moves to cut the unlocking shear pin 46. As Figures 5 - 7 shown, in order to conveniently unlock the central tube 41 and the outer tube 42, the fixing member passes through the moving member and the outer tube 42, the fixing member is closely attached to the central tube 41, and an elastic member sleeved on the moving member is provided between the fixing member and the outer tube 42. An accommodating groove 4203 for accommodating the elastic member is provided on the outer tube 42; the elastic member has a locked state in which it is axially stop-fitted with both the central tube 41 and the accommodating groove 4203 before the fixing member is cut, so that the central tube 41 and the outer tube 42 are indirectly fixedly connected through the fixing member. The elastic member also has an unlocked state in which it disengages from the accommodating groove 4203 after the fixing member is cut, so that the central tube 41 and the outer tube 42 can move relative to each other axially. Specifically, the elastic member is a snap ring 411.

[0041] As Figure 5 shown, when the packer unlocking tool 4 is not unlocked, the unlocking shear pin 46 (i.e., the fixing member) connects the outer tube 42 and the unlocking piston 43 (i.e., the moving member), and the snap ring 411 is located in the accommodating groove 4203. At this time, the snap ring 411 clamps the central tube 41, and at the same time, the snap ring is stop-fitted with the accommodating groove 4203, thereby preventing the central tube 41 and the outer tube 42 from moving relative to each other.

[0042] As Figure 6 shown, after the pressure in the central tube 41 reaches the unlocking pressure, the unlocking piston 43 cuts the unlocking shear pin 46. At this time, the snap ring 411 does not contact the central tube 41, thereby realizing the unlocking of the central tube 41 and the outer tube 42 and putting the packer unlocking tool 4 into a working state. Specifically, as Figure 6 shown, the unlocking piston 43 can move upward to cut the unlocking shear pin 46; in other specific embodiments, the unlocking shear pin 46 can also be arranged at the upper part of the unlocking space, and the unlocking piston 43 moves downward to cut the unlocking shear pin 46. At the same time, as Figure 6 shown, in this specific embodiment, the moving member and the central tube 41 are always in sealing cooperation axially. After the fixing member is cut, the liquid in the central tube 41 can enter between the moving member and the central tube 41 and apply an upward force to the moving member, thereby applying an upward force to the central tube 41 to prevent the layered pipe string structure 1 from creeping.

[0043] As Figure 7 shown, when unlocking by pulling upward, the central tube 41 moves upward and drives the snap ring 411 to move upward. At this time, the snap ring 411 disengages from the accommodating groove 4203, and the outer tube 42 and the central tube 41 can slide relative to each other axially.

[0044] The central tube 41 is communicated with the unlocking space through the unlocking liquid inlet hole 45. When there is pressure in the central tube 41, the pressure will be transmitted to the movable part through the unlocking liquid inlet hole 45, thereby driving the movable part to move, so that the movable part can cut the fixing part, thus conveniently realizing the unlocking of the central tube 41 and the outer tube 42.

[0045] However, in other specific embodiments, any locking mechanism in the prior art that fixedly connects the central tube 41 and the outer tube 42 and can unlock the central tube 41 and the outer tube 42 after pressurizing in the central tube 41 can also be adopted. For example, the fixing part is an elastic locking block squeezed between the movable part and the accommodating groove 4203, and the unlocking liquid inlet hole 45 is arranged on one side of the circumferential direction of the movable part. When the pressure in the central tube 41 reaches the unlocking pressure, the movable part moves circumferentially, and the elastic locking block returns to its original length, thereby realizing unlocking. When the central tube 41 is lifted, the elastic locking block rotates and disengages from the accommodating groove 4203, and the elastic locking block does not interfere with the central tube 41 and the outer tube 42. In other specific embodiments, the locking mechanism can also be the unsealing mechanism on the packer 3.

[0046] Of course, in other specific embodiments, the elastic member can also be an elastic member such as a rubber band; the elastic member can also not be provided, and the unlocking shear pin 46 is directly connected to the central tube 41, the outer tube 42, and the unlocking piston 43.

[0047] In different specific embodiments, the packer unsealing tool 4 can be provided only between two adjacent packers 3, or the packer unsealing tool 4 and the connecting tubing connected in series can be provided between two adjacent packers 3 at the same time.

[0048] Such as Figure 4 and Figure 8 As shown, in order to conveniently make the unlocking pressure greater than the setting pressures of the upper and lower two-stage packers 3 adjacent to the corresponding packer unsealing tool 4, as a specific embodiment, the working area of the movable part corresponding to the pressure in the central tube 41 is smaller than the working area of the setting mechanism of the corresponding packer 3 corresponding to the pressure in the central tube 41. By reducing the working area of the movable part corresponding to the pressure in the central tube 41, when the specifications of the setting shear pin of the packer 3 and the unlocking shear pin 46 of the packer unsealing tool 4 are the same, since the force received by the shear pin is equal to the pressure in the central tube 41 multiplied by the corresponding working area, the force received by the setting shear pin is always greater than the force received by the unlocking shear pin 46. Therefore, after the packer 3 is set, it is convenient to continue to increase the pressure in the central tube 41 to cut the unlocking shear pin 46, so that the packer unsealing tool 4 is in a working state where relative movement can occur between the central tube 41 and the outer tube 42.

[0049] Of course, in other specific embodiments, the strength of the unlocking shear pin 46 can also be made higher than that of the setting shear pin to ensure that the unlocking shear pin 46 is cut off after the packer 3 is set.

[0050] As Figure 2 and Figure 8 shown, in order to balance the influence of the casing pressure on the packer release tool 4, the inner stop portion includes a first inner stop portion 491. The first inner stop portion 491 is in axial sealing fit with both the central tube 41 and the outer tube 42. And on the outer tube 42, there is a first outer stop portion 471 that can move synchronously with the outer tube 42 and corresponds to the first inner stop portion 491. The first outer stop portion 471 is in axial sealing fit with both the central tube 41 and the outer tube 42. A first accommodation space communicating with the outside of the outer tube 42 is formed among the first inner stop portion 491, the central tube 41, the outer tube 42, and the first outer stop portion 471. Specifically, the first accommodation space communicates with the inside of the casing 7 of the oil well through the casing pressure balancing liquid inlet hole 48 on the outer tube 42.

[0051] When the casing pressure is greater than the oil pressure, the liquid in the casing 7 enters the first accommodation space through the casing pressure balancing liquid inlet hole 48. And the liquid in the first accommodation space exerts an upward acting force on the first outer stop portion 471, that is, an upward acting force on the outer tube 42, to prevent the stratified pipe string structure 1 from creeping. At the same time, the liquid in the casing 7 exerts a downward acting force on the rubber cylinder of the next-stage packer 3. By providing the first accommodation space, the casing pressure balancing liquid inlet hole 48, and the first outer stop portion 471, when the casing pressure is greater than the oil pressure, the outer tube 42 can exert an upward force on the next-stage packer 3 to prevent the next-stage packer 3 from moving downward, thereby preventing the stroke provided by the packer release tool 4 from decreasing. Specifically, the stroke provided by the packer release tool 4 is: the axial length from the first inner stop portion 491 to the first outer stop portion 471 along the axis, and this part also constitutes the first accommodation space.

[0052] Of course, in other specific embodiments, when the difference between the oil pressure and the casing pressure is small, the first accommodation space can also not be provided, and the friction between the packer 3 and the casing 7 is relied on to ensure that the packer 3 does not move.

[0053] To better balance the influence of the casing pressure on the packer release tool 4, as an optimized specific embodiment, between two adjacent stages of packers 3, the projected area in the axial direction of the contact surface of the first outer stop portion 471 for contacting the liquid in the first accommodation space is equal to the projected area in the axial direction of the sealing rubber cylinder of the next-stage packer 3.

[0054] The projected area in the axial direction of the contact surface of the first outer stop portion 471 for contacting the liquid in the first accommodation space is made equal to the projected area in the axial direction of the sealing rubber cylinder of the next-stage packer 3, that is, the downward force exerted by the liquid in the casing 7 on the next-stage packer 3 is the same as the upward force exerted by the liquid in the casing 7 on the outer tube 42, so as to ensure that the next-stage packer 3 will not move when the casing pressure is greater than the oil pressure.

[0055] Of course, in other specific embodiments, the projected area in the axial direction of the contact surface of the first outer stop portion 471 for contacting the liquid in the first accommodation space may not be equal to the projected area in the axial direction of the sealing rubber cylinder of the next-stage packer 3. Specifically, when the projected area in the axial direction of the contact surface of the first outer stop portion 471 for contacting the liquid in the first accommodation space is relatively large, the upward force received by the outer tube 42 can overcome the pressure of the liquid in the casing 7 on the next-stage packer 3 and can also balance the gravity of the next-stage packer 3; when the projected area in the axial direction of the contact surface of the first outer stop portion 471 for contacting the liquid in the first accommodation space is relatively small, the relative movement between the central tube 41 and the outer tube 42 of the packer release tool 4 is ensured by relying on the frictional force between the next-stage packer 3 and the casing 7.

[0056] Specifically, as Figure 2 shown, only one packer release tool 4 is provided between two adjacent stages of packers 3. However, in other specific embodiments, two packer release tools 4 are provided between two adjacent stages of packers 3, and the sum of the projected areas in the axial direction of the contact surfaces of the first outer stop portions 471 of each packer release tool 4 for contacting the liquid in the first accommodation space is equal to the projected area in the axial direction of the sealing rubber cylinder of the next-stage packer 3. Of course, three, four or more packer release tools 4 may also be provided between two adjacent stages of packers 3, as long as the sum of the projected areas in the axial direction of the contact surfaces of the first outer stop portions 471 of each packer release tool 4 for contacting the liquid in the first accommodation space is equal to the projected area in the axial direction of the sealing rubber cylinder of the next-stage packer 3.

[0057] By providing at least two packer release tools 4 between two adjacent stages of packers 3, the maximum outer diameter of a single packer release tool 4 can be reduced, that is, the maximum outer diameter of the layered pipe string structure 1 before setting is reduced, which is convenient for lowering the layered pipe string structure 1 into the well.

[0058] Such as Figure 1 and Figure 9As shown in the figure, in order to balance the influence of the oil pressure on the packer release tool 4, as a specific implementation manner, the inner stop portion of the packer release tool 4 further includes a second inner stop portion 492. The second inner stop portion 492, the central tube 41 and the outer tube 42 are all in sealing fit along the axial direction. And the outer tube 42 is provided with a second outer stop portion 472 that can move synchronously with the outer tube 42 and corresponds to the second inner stop portion 492. The second outer stop portion 472, the central tube 41 and the outer tube 42 are all in sealing fit along the axial direction. A second accommodation space communicating with the inside of the central tube 41 is formed among the second inner stop portion 492, the central tube 41, the outer tube 42 and the second outer stop portion 472. Specifically, the second accommodation space communicates with the central tube 41 through an oil pressure balancing liquid inlet hole 410.

[0059] When the oil pressure is greater than the casing pressure, the pressure in the central tube 41 will act on the bottom sealing structure 5 of the stratified tubing string structure 1, resulting in a downward force on the lowermost packer 3. By providing the second accommodation space, the liquid in the central tube 41 can enter the second accommodation space through the oil pressure balancing liquid inlet hole 410, and apply an upward force to the second outer stop portion 472, so that the outer tube 42 applies an upward force to the next-stage packer 3, thereby preventing the next-stage packer 3 from moving; at the same time, it can prevent the stratified tubing string structure 1 from creeping.

[0060] As Figure 1 shown, as a specific implementation manner, all the packer release tools 4 are provided with a second accommodation space. Among them, the second accommodation space of the lowermost packer release tool 4 is used to balance the oil pressure; the second accommodation spaces of the remaining packer release tools 4 are used to apply an upward force to the next-stage packer 3, so as to balance the gravity of the next-stage packer 3 and prevent the stratified tubing string structure 1 from creeping. However, in other specific implementation manners, the second accommodation space may also be provided only in the lowermost packer release tool 4.

[0061] Setting the first accommodation space and the second accommodation space at the same time can ensure that the lowermost packer 3 is not affected by the oil pressure and the casing pressure, so as to ensure that there is no relative movement between the outer tube 42 and the central tube 41. However, in other specific implementation manners, when the difference between the oil pressure and the casing pressure is small, the first accommodation space or the second accommodation space may be provided alone, and the friction force between the packer 3 and the casing 7 is used to ensure that there is no relative movement between the central tube 41 and the outer tube 42 of the packer release tool 4.

[0062] Of course, in different specific embodiments, the projected area in the axial direction of the contact surface of the second outer stop portion 472 of the lowermost packer release tool 4 for contacting the liquid in the second accommodation space can also be made equal to the projected area in the axial direction of the contact surface between the bottom sealing structure 5 of the layered pipe string structure 1 and the liquid in the layered pipe string structure 1, so as to enable the packer release tool 4 to completely balance the downward force of the oil pressure on the lowermost packer 3.

[0063] Of course, in different specific embodiments, the projected area in the axial direction of the contact surface of the second outer stop portion 472 of the lowermost packer release tool 4 for contacting the liquid in the second accommodation space may not be equal to the projected area in the axial direction of the contact surface between the bottom sealing structure 5 of the layered pipe string structure 1 and the liquid. Specifically, when the projected area in the axial direction of the contact surface of the second outer stop portion 472 for contacting the liquid in the second accommodation space is small, the friction between the packer 3 and the casing 7 is relied on to ensure that there is no relative movement between the central pipe 41 and the outer pipe 42 of the packer release tool 4; when the projected area in the axial direction of the contact surface of the second outer stop portion 472 for contacting the liquid in the second accommodation space is large, after the upward force of the liquid in the central pipe 41 on the outer pipe 42 offsets the influence of the oil pressure on the lowermost packer 3, it can also balance part of the gravity of the lowermost packer 3.

[0064] As Figure 4 and Figures 8 - 9 shown, for the convenience of assembling the packer release tool 4, as a specific embodiment, the central pipe 41 is of a split structure. Specifically, the central pipe 41 is fixedly connected in sequence by an upper joint 4101, a first connecting pipe 4102 and a second connecting pipe 4103. The unlocking space is formed by the outer pipe 42 and the upper part of the upper joint 4101 and the first connecting pipe 4102; a first accommodation space is formed among the lower part of the first connecting pipe 4102, the upper part of the second connecting pipe 4103 and the outer pipe 42, and the upper part of the second connecting pipe 4103 constitutes an inner stop portion; an inner stop portion is fixedly connected to the lower part of the second connecting pipe 4103, and a second accommodation space is formed among the inner stop portion, the first connecting pipe 4102 and the outer pipe 42. By setting the central pipe 41 into several sections, it is convenient to assemble the packer release tool 4. Specifically, in this specific embodiment, the outer pipe 42 includes a lower joint 4201 and an outer cylinder 4202. The outer cylinder 4202 is divided into three sections of cylinders, and an outer stop portion connected to one of the outer cylinders 4202 is provided between adjacent two sections of cylinders.

[0065] As Figure 4 and Figures 8 - 9As shown, the assembly process of this specific embodiment is introduced by taking an assembly method as an example. However, in other assembly methods, assembly can also be carried out in other assembly sequences. When assembling, S1: Thread-connect the lower joint 4201 and the lowermost cylinder body; S2: Insert the second inner stop portion 492 into the lowermost cylinder body; S3: Lap the second outer stop portion 472 on the lowermost cylinder body; S4: Thread-connect the second connecting pipe 4103 and the second inner stop portion 492, and make the second connecting pipe 4103 and the lowermost cylinder body clamp the second outer stop portion 472; S5: Thread-connect the middle cylinder body to the second outer stop portion 472; S6: Lap the first outer stop portion 471 on the middle cylinder body; S7: Thread-connect the first connecting pipe 4102 and the second connecting pipe 4103, and make the first connecting pipe 4102 and the middle cylinder body clamp the first outer stop portion 471; S8: Thread-connect the uppermost cylinder body to the first connecting pipe 4102; S9: Thread-connect the upper joint 4101 and the first connecting pipe 4102. The sealing performance can be ensured by setting a sealing ring 44 on the contact surface of adjacent components.

[0066] Of course, in other specific embodiments, the second accommodation space can also be located above the first accommodation space. At the same time, in other specific embodiments, the central pipe 41 can also be integrally formed, and the three cylinder bodies and the outer stop portions can be thread-connected to the outside of the central pipe 41 in sequence, which will not be elaborated here. Or, in other specific embodiments, two interconnected components can also be fixedly connected by means such as plugging.

[0067] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, for those skilled in the art, they can still make modifications to the technical solutions described in the foregoing embodiments without creative efforts, or make equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A packer release tool, characterized in that, It includes a central tube for connecting with the upper-stage lifting and releasing packer and an outer tube for connecting with the lower-stage lifting and releasing packer. An inner stop portion is provided on the central tube, which can move synchronously with the central tube and is used for axially stop-fitting with the outer tube after the central tube is lifted by a certain stroke, so that the central tube can drive the outer tube to move upward. The central tube and the outer tube are fixedly connected by a locking mechanism unlocked by using the pressure inside the central tube, and the unlocking pressure corresponding to the locking mechanism satisfies: the unlocking pressure is greater than the setting pressures of the corresponding upper-stage packer and lower-stage packer.

2. The packer release tool according to claim 1, characterized in that, An unlocking space is provided between the central tube and the outer tube. An unlocking liquid inlet hole communicating the unlocking space and the central tube is provided on the central tube. The central tube and the outer tube are directly or indirectly fixedly connected by a fixing member. An active member for shearing the fixing member is also provided in the unlocking space. The active member, the unlocking space, the unlocking liquid inlet hole and the fixing member together constitute the locking mechanism.

3. The packer release tool according to claim 2, wherein The fixing member passes through the active member and the outer tube, and is closely attached to the central tube. An elastic member sleeved on the active member is provided between the fixing member and the outer tube. A receiving groove for accommodating the elastic member is provided on the outer tube. The elastic member has a locking state in which it axially stop-fits with both the central tube and the receiving groove before the fixing member is sheared, so that the central tube and the outer tube are indirectly fixedly connected by the fixing member. The elastic member also has an unlocking state in which it disengages from the receiving groove after the fixing member is sheared, so that relative axial movement can occur between the central tube and the outer tube.

4. The packer release tool according to claim 2 or 3, characterized in that, The working area of the active member corresponding to the pressure inside the central tube is smaller than the working area of the setting mechanism of the corresponding packer corresponding to the pressure inside the central tube.

5. The packer release tool according to claim 1, wherein, The inner stop portion includes a first inner stop portion. The first inner stop portion axially seals and fits with both the outer tube and the central tube. A first outer stop portion corresponding to the first inner stop portion and capable of moving synchronously with the outer tube is provided on the outer tube. The first outer stop portion axially seals and fits with both the outer tube and the central tube. A first accommodating space communicating with the outside of the outer tube is formed among the first inner stop portion, the central tube, the outer tube and the first outer stop portion.

6. The packer releasing tool according to claim 5, wherein The projected area in the axial direction of the contact surface of the first outer stop portion for contacting the liquid in the first accommodating space is equal to the projected area in the axial direction of the sealing rubber cylinder of the lower-stage packer.

7. The packer release tool according to claim 5, characterized in that, The inner stop portion of the packer releasing tool further includes a second inner stop portion. The second inner stop portion axially seals and fits with both the central tube and the outer tube. A second outer stop portion corresponding to the second inner stop portion and capable of moving synchronously with the outer tube is provided on the outer tube. The second outer stop portion axially seals and fits with both the central tube and the outer tube. A second accommodating space communicating with the inside of the central tube is formed among the second inner stop portion, the central tube, the outer tube and the second outer stop portion.

8. The packer release tool according to claim 7, characterized in that, The projected area in the axial direction of the contact surface of the second outer stop portion for contacting the liquid in the second accommodating space is equal to the projected area in the axial direction of the contact surface between the bottom sealing structure of the layered pipe string structure and the liquid inside the layered pipe string structure.

9. The packer releasing tool according to claim 7, wherein The central tube is fixedly connected in sequence by an upper joint, a first connecting pipe and a second connecting pipe. An unlocking space is formed between the outer tube, the upper joint and the upper part of the first connecting pipe. A first accommodating space or a second accommodating space is formed among the lower part of the first connecting pipe, the upper part of the second connecting pipe and the outer tube. The upper part of the second connecting pipe constitutes an inner stop portion. An inner stop portion is fixedly connected to the lower part of the second connecting pipe. A second accommodating space or a first accommodating space is formed among the inner stop portion, the first connecting pipe and the outer tube.

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