High-curvature flexible ultra-short radius well completion pipe string

Abstract

The invention discloses a high-curvature flexible ultra-short radius well completion pipe string, and belongs to the technical field of oil and gas exploitation equipment. The high-curvature flexible ultra-short radius well completion pipe string comprises a guiding shoe and a plurality of screen pipes, and further comprises a plurality of flexible short sections, and each flexible short section comprises a universal ball seat and a universal ball head; the universal ball seat is connected with a drill rod for well completion or one of the sieve pipes, and a first through hole is formed in the universal ball seat; one end of the universal ball head is hinged to the universal ball seat, a second through hole is formed in the universal ball head, and a pipe hole of the screen pipe is communicated with the first through hole and the second through hole; and the tension locking joint is used for reducing stress among the plurality of screen pipes. According to the high-curvature flexible ultra-short-radius well completion pipe string, the resistance of a deflecting section of a borehole to the pipe string during tripping-in is reduced, the stress among a plurality of screen pipes can be reduced, the axial force borne by each section of screen pipe during tripping-in is reduced, and the difficulty degree of tripping-in of the whole pipe string into the borehole is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of oil and gas production equipment, and in particular to a high-curvature flexible ultra-short radius completion pipe string. Background Art

[0002] With the deepening of the development of old oil fields, the water content of oil fields has gradually increased, the crude oil production has gradually decreased, and the development situation has become more severe. In addition, with the continuous construction of infill wells, the distance between wells has become shorter and shorter. Under the constraints of long deflection sections and short well spacing in conventional horizontal wells, the short horizontal section affects the oil production effect. For this reason, in recent years, short-radius and ultra-short-radius horizontal well technologies have been used to carry out large-curvature deflection and directional horizontal drilling, which can achieve directional potential tapping and transformation of the target layer, expand the oil leakage area, improve the production conditions of the oil wells, and further improve the crude oil recovery rate. Compared with conventional horizontal wells, it has the characteristics of short target front distance, short construction period, low cost, high wellbore trajectory deflection rate (more than 60° / 30m) and small curvature radius (within 50m), which makes it extremely difficult to run the completion string.

[0003] At present, conventional oil pipes, slotted screens and other oil well completion pipe strings are composed of pipe bodies and couplings. They are bent only by the yield strength of the pipe body material. Therefore, they have high rigidity and limited bending capacity, which makes it difficult or impossible to run them into high dogleg wells, and cannot meet the completion requirements. Summary of the invention

[0004] The purpose of the present invention is to overcome the problems in the prior art and provide a high-curvature flexible ultra-short radius completion pipe string, which can enable the entire pipe string to gradually deflect as the wellbore deflects, thereby reducing the resistance of the wellbore's deflection section to the pipe string when it is lowered, making each screen pipe easier to deflect and reducing the difficulty of the entire pipe string when it is lowered into the wellbore.

[0005] The present invention provides a high-curvature flexible ultra-short radius completion pipe string, comprising a guide shoe and a plurality of screen pipes, wherein the plurality of screen pipes are connected end to end, and further comprising:

[0006] A plurality of flexible short sections are arranged alternately with the plurality of screen tubes, two adjacent screen tubes are connected by a flexible short section, and each flexible short section includes a universal ball seat and a universal ball head;

[0007] The universal ball seat is connected to the drill pipe or one of the screen tubes used for well completion, and a first through hole is provided in the universal ball seat;

[0008] One end of the universal ball head is hinged to the universal ball seat, and the other end of the universal ball head is connected to another screen tube. A second through hole is provided in the universal ball head, and the tube hole of the screen tube is connected to the first through hole and the second through hole.

[0009] A tension locking joint has one end connected to the last screen pipe and the other end connected to the guide shoe. The tension locking joint is used to reduce stress between multiple screen pipes.

[0010] Preferably, the tension locking joint includes a core shaft and a guide shoe joint, one end of the core shaft is connected to the end of the screen pipe away from the guide shoe, one end of the guide shoe joint is connected to the guide shoe, the other end of the guide shoe joint is provided with a step hole, the other end of the core shaft is slidably connected in the step hole along the axial direction of the step hole, the side wall of the step hole is provided with a threaded hole along the radial direction of the core shaft, the threaded hole is threadedly connected with a lock nut stabilizing pin, and the lock nut stabilizing pin is pressed against the outer wall of the core shaft to limit the movement of the core shaft relative to the step hole.

[0011] Preferably, a slip ring is provided on the outer wall of one end of the core shaft near the step hole, and the core shaft is connected to the step hole by the slip ring through the axial sliding of the step hole. A core shaft lock nut is detachably connected in the step hole, and the core shaft lock nut abuts against the slip ring. The core shaft lock nut is used to prevent the slip ring from falling out of the step hole.

[0012] Preferably, a screen pipe joint is provided at the end of the core shaft away from the slip ring, and the core shaft is detachably connected to the end of the screen pipe away from the guide shoe through the screen pipe joint. A pressure-reducing gasket is provided in the step hole, and the pressure-reducing gasket has a certain elasticity. The end of the core shaft close to the guide shoe can abut against the pressure-reducing gasket, and the pressure-reducing gasket is used to apply an elastic force along the axial direction of the step hole to the core shaft.

[0013] Preferably, a tenon mechanism is provided between the drill rod and the universal ball seat, one end of the tenon mechanism is connected to the drill rod, and the other end of the tenon mechanism is connected to the universal ball seat, and the tenon mechanism is used to achieve connection or disconnection between the drill rod and the universal ball seat.

[0014] Preferably, the tenon mechanism includes a drill rod joint, a sliding sleeve upper joint, a sliding sleeve lower joint and a claw mechanism, the drill rod joint is connected to the drill rod, the sliding sleeve upper joint is connected to the universal ball seat, the sliding sleeve lower joint is arranged outside the sliding sleeve upper joint and connected to the sliding sleeve upper joint, the outer wall of the sliding sleeve lower joint is provided with a plurality of grooves, the claw mechanism is arranged outside the sliding sleeve lower joint and connected to the drill rod joint, the claw mechanism can be engaged with the plurality of grooves, and the claw mechanism is used to lock or release the position of the sliding sleeve upper joint relative to the drill rod joint.

[0015] Preferably, the claw mechanism includes a claw and a driving mechanism, the drill pipe joint is inserted into the upper joint of the sliding sleeve, the claw includes a connecting ring and a plurality of claw arms, the plurality of claw arms all have a certain elasticity, the connecting ring is fixedly connected to the outer wall of the drill pipe joint, the plurality of claw arms are arranged on one side of the connecting ring, the lower joint of the sliding sleeve is arranged in the plurality of claw arms, the driving mechanism is connected to the plurality of claw arms, and the driving mechanism is used to drive the claw arms to be clamped into the clamping groove to limit the movement of the upper joint of the sliding sleeve relative to the upper joint of the drill pipe.

[0016] Preferably, the driving mechanism includes a sleeve and a hydraulic control circuit, the sleeve is connected to the outside of the sleeve lower joint along its own axial sliding, the multiple claw arms abut against the inner wall of one end of the sleeve, the sleeve is used to squeeze each claw arm into a slot, and a sealing cavity is provided between the inner wall of the other end of the sleeve and the outer wall of the sleeve lower joint, the hydraulic control circuit is connected to the sealing cavity, when the hydraulic control circuit passes hydraulic oil into the sealing cavity, the hydraulic oil drives the sleeve to move away from one end of the claw arm, so that the inner wall of the sleeve is out of contact with the claw arm, thereby causing the claw arm to escape from the slot.

[0017] Preferably, the lower joint of the sleeve and the side wall of the sleeve are provided with pin holes along the radial direction of the sleeve, and a limit pin is provided in the pin hole. When the hydraulic oil in the sealing chamber reaches a certain pressure, the hydraulic oil drives the sleeve to shear the limit pin. A limit retaining ring is provided on the outer wall of the lower joint of the sleeve, and the limit retaining ring can abut against the end of the sleeve away from the claw arm. The limit retaining ring is used to prevent the sleeve from slipping off the lower joint of the sleeve.

[0018] Preferably, a ball head locking ring is provided in the universal ball seat, the ball head locking ring is connected to one end of the universal ball seat close to the universal ball head, the ball head locking ring abuts against the outer wall of the universal ball head, and the ball head locking ring is used to limit the displacement of the universal ball head relative to the universal ball seat.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows: a high-curvature flexible ultra-short radius completion pipe string of the present invention, with the continuous feeding of the drill pipe, the deflection amplitude of the screen pipe close to the guide shoe is greater than the screen pipe close to the drill pipe, and the angle between the two adjacent screen pipes changes, so that the flexible short section universal ball head rotates relative to the flexible short section universal ball seat, and since the multiple flexible short sections and the multiple screen pipes are staggered, the deflection of each section of the screen pipe relative to the adjacent screen pipes is continuous, so that the entire pipe string can gradually deflect with the deflection of the wellbore, reducing the resistance of the wellbore's deflection section to the pipe string when it is lowered, thereby reducing the difficulty of the entire pipe string being lowered into the wellbore, and under the action of the tension locking joint, the stress between the multiple screen pipes can be reduced, and the axial force received by each section of the screen pipe when it is lowered can be reduced, so that each screen pipe is easier to deflect, reducing the difficulty of the entire pipe string being lowered into the wellbore.

[0020] The tension locking joint of the device, under the action of the lock nut stabilizing nail, the compression force applied by the lock nut to the outer wall of the core shaft can prevent the core shaft from moving relative to the guide shoe joint, and can release the stress between multiple screens, thereby reducing the extrusion force between the universal ball head and the universal ball seat, so that multiple screens are more likely to deflect, further reducing the difficulty of the entire pipe string in entering the wellbore. By setting a pressure-relief gasket, the pressure-relief gasket can apply an elastic force along the axial direction of the step hole to the core shaft, thereby buffering the movement of the core shaft relative to the guide shoe joint, thereby further reducing the stress between multiple screens, and further reducing the difficulty of the entire pipe string in entering the wellbore. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a structural schematic diagram of the present invention;

[0022] Figure 2 It is a structural schematic diagram of the tenon mechanism of the present invention;

[0023] Figure 3 It is a structural schematic diagram of the universal ball head of the present invention;

[0024] Figure 4 It is a schematic structural diagram of the tension locking joint of the present invention.

[0025] Description of reference numerals:

[0026] 101. guide shoe, 102. screen tube, 103. flexible short joint, 104. universal ball seat, 105. universal ball head, 106. ball head locking ring, 107. tension locking joint, 108. first through hole, 109. second through hole, 201. mandrel, 202. guide shoe joint, 203. step hole, 204. lock nut stabilizer nail, 301. slip ring, 302. mandrel lock nut, 401. screen tube joint, 402. pressure relief gasket, 5. tenon mechanism, 601. drill pipe joint, 602. upper joint of sliding sleeve, 603. lower joint of sliding sleeve, 604. claw mechanism, 605. slot, 606. ball seat joint, 701. claw arm, 702. connecting ring, 801. sliding sleeve, 802. sealing chamber, 901. limit pin, 902. limit retaining ring. DETAILED DESCRIPTION

[0027] The following is combined with Figure 1-Figure 4 , the specific implementation of the present invention is described in detail, but it should be understood that the protection scope of the present invention is not limited by the specific implementation. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0028] like Figure 1-Figure 4As shown, the high-curvature flexible ultra-short radius completion pipe string provided by the present invention includes a guide shoe 101 and a plurality of screen tubes 102, wherein the plurality of screen tubes 102 are connected end to end, and further includes: a plurality of flexible short sections 103 and a tension locking joint 107, wherein the plurality of flexible short sections 103 are staggeredly arranged with the plurality of screen tubes 102, and two adjacent screen tubes 102 are connected by a flexible short section 103, and each flexible short section 103 includes a universal ball seat 104, a universal ball head 105 and a ball head locking ring 106; the universal ball seat 104 is connected to a drill pipe for completion or one of the screen tubes 102 A first through hole 108 is provided in the universal ball seat 104; one end of the universal ball head 105 is hinged to the universal ball seat 104, and the other end of the universal ball head 105 is connected to another screen tube 102; a second through hole 109 is provided in the universal ball head 105, and the tube hole of the screen tube 102 is communicated with the first through hole 108 and the second through hole 109; one end of the tension locking joint 107 is connected to the last screen tube 102, and the other end of the tension locking joint 107 is connected to the guide shoe 101, and the tension locking joint 107 is used to reduce the stress between multiple screen tubes 102.

[0029] The working principle of the above embodiment is briefly described:

[0030] When the device is in use, the drill pipe is connected with the guide shoe 101, the tension locking joint 107, the plurality of screens 102 and the plurality of flexible short sections 103, the guide shoe 101 is inserted into the wellbore, and the drill rig is used to drive the drill pipe into the wellbore, thereby driving the tension locking joint 107, the plurality of screens 102 and the plurality of flexible short sections 103 to move into the wellbore. When the dogleg degree of the wellbore is high, the guide shoe 101 will deviate along the wellbore, and then drive the screen 102 to deflect. With the continuous feeding of the drill pipe, the deflection amplitude of the screen 102 close to the guide shoe 101 is greater than that of the screen 102 close to the drill pipe, and the angle between the two adjacent screens 102 changes, so that the flexible short section 103 is The ball head 105 rotates relative to the flexible short joint 103 universal ball seat 104. Since the multiple flexible short joints 103 and the multiple screen tubes 102 are staggered, the deflection of each screen tube 102 relative to the adjacent screen tube 102 is continuous, so that the entire pipe string can be gradually deflected with the deflection of the wellbore, reducing the resistance of the wellbore's deflection section to the pipe string when it is lowered, thereby reducing the difficulty of lowering the entire pipe string into the wellbore. In this process, under the action of the tension locking joint 107, the stress between the multiple screen tubes 102 can be reduced, and the axial force received by each screen tube 102 when it is lowered can be reduced, so that each screen tube 102 is easier to deflect, further reducing the difficulty of lowering the entire pipe string into the wellbore.

[0031] The high-curvature flexible ultra-short radius completion pipe string of the present invention can make the entire pipe string gradually deflect with the deflection of the wellbore, reduce the resistance of the wellbore's deflection section to the pipe string when it is lowered, and can reduce the stress between multiple screens 102, and reduce the axial force on each section of the screen 102 when it is lowered, so that each screen 102 is easier to deflect, reducing the difficulty of the entire pipe string when it is lowered into the wellbore.

[0032] On the basis of the above embodiment, in order to reduce the squeezing force between the universal ball head 105 and the universal ball seat 104, the multiple screens 102 are more easily deflected, thereby further reducing the difficulty of the entire pipe string in being lowered into the wellbore.

[0033] like Figure 1 and Figure 4 As shown, the tension locking joint 107 includes a core shaft 201 and a lead shoe joint 202, one end of the core shaft 201 is connected to the end of the screen pipe 102 away from the lead shoe 101, one end of the lead shoe joint 202 is connected to the lead shoe 101, and the other end of the lead shoe joint 202 is provided with a step hole 203, the other end of the core shaft 201 is slidably connected in the step hole 203 along the axial direction, the side wall of the step hole 203 is provided with a threaded hole along the radial direction of the core shaft 201, and a lock nut stabilizing nail 204 is threadedly connected in the threaded hole, and the lock nut stabilizing nail 204 is pressed against the outer wall of the core shaft 201 to limit the movement of the core shaft 201 relative to the step hole 203.

[0034] When the pipe string is lowered into the wellbore, when the wellbore deviates, the guide shoe 101 will be subjected to the axial squeezing force exerted by the side wall of the wellbore along the screen tube 102. Under the action of the lock nut stabilizing nail 204, the pressing force exerted by the lock nut to the outer wall of the core shaft 201 can prevent the core shaft 201 from moving relative to the guide shoe joint 202, thereby preventing the guide shoe 101 from moving relative to the screen tube 102. This extrusion pressure will increase the stress between the multiple screen tubes 102, and the stress will be transmitted to the universal ball head 105, increasing the extrusion pressure applied by the universal ball head 105 to the universal ball seat 104, making it more difficult for the universal ball head 105 to rotate relative to the universal ball seat 104. When the extrusion pressure on the guide shoe 101 is too large, the pressing force applied by the lock nut stabilizer nail 204 to the outer wall of the core shaft 201 is insufficient, and the guide shoe 101 will drive the guide shoe joint 202 to move toward the core shaft 201, so that the core shaft 201 is inserted into the step hole 203, releasing the stress between the multiple screen tubes 102, thereby reducing the extrusion pressure between the universal ball head 105 and the universal ball seat 104, making the multiple screen tubes 102 more likely to deflect, further reducing the difficulty of the entire pipe string in lowering into the wellbore.

[0035] As a preferred solution, Figure 1 and Figure 4As shown, a slip ring 301 is provided on the outer wall of one end of the mandrel 201 near the step hole 203, and the mandrel 201 is connected to the step hole 203 by sliding along the axial direction of the step hole 203 through the slip ring 301. A mandrel lock nut 302 is detachably connected to the step hole 203, and the mandrel lock nut 302 abuts against the slip ring 301. The mandrel lock nut 302 is used to prevent the slip ring 301 from coming out of the step hole 203. The mandrel 201 is connected to the step hole 203 by sliding along the axial direction of the step hole 203 through the slip ring 301. When the mandrel 201 drives the slip ring 301 to slide along the axial direction of the step hole 203, the mandrel lock nut 302 in the step hole 203 can limit the maximum displacement of the slip ring 301, thereby preventing the slip ring 301 from coming out of the step hole 203, thereby preventing the guide shoe 101 from being disconnected from the screen pipe 102, and thus ensuring the normal operation of the entire pipe string.

[0036] As a preferred solution, Figure 1 and Figure 4 As shown, a screen pipe joint 401 is provided at one end of the mandrel 201 away from the slip ring 301, and the mandrel 201 is detachably connected to the end of the screen pipe 102 away from the guide shoe 101 through the screen pipe joint 401, and a pressure relief gasket 402 is provided in the step hole 203, and the pressure relief gasket 402 has a certain elasticity, and the end of the mandrel 201 close to the guide shoe 101 can abut against the pressure relief gasket 402, and the pressure relief gasket 402 is used to apply an elastic force along the axial direction of the step hole 203 to the mandrel 201. By providing the screen pipe joint 401, the shaft is detachably connected to the end of the screen pipe 102 away from the guide shoe 101 through the screen pipe joint 401, which can facilitate the disassembly and assembly of the guide shoe 101 and the screen pipe 102. When the core shaft 201 is inserted into the step hole 203, the end of the core shaft 201 close to the guide shoe 101 can abut against the pressure-relief gasket 402. Since the pressure-relief gasket 402 has a certain elasticity, the pressure-relief gasket 402 can apply an elastic force along the axial direction of the step hole 203 to the core shaft 201, thereby buffering the movement of the core shaft 201 relative to the guide shoe joint 202, thereby further reducing the stress between the multiple screens 102 and further reducing the difficulty of lowering the entire pipe string into the wellbore.

[0037] As a preferred solution, Figure 1 As shown, a tenon mechanism 5 is provided between the drill pipe and the universal ball seat 104, one end of the tenon mechanism 5 is connected to the drill pipe, and the other end of the tenon mechanism 5 is connected to the universal ball seat 104, and the tenon mechanism 5 is used to achieve connection or separation between the drill pipe and the universal ball seat 104. By providing the tenon mechanism 5, the drill pipe and the universal ball seat 104 are connected together by using the tenon mechanism 5, so as to complete the connection between the multiple screen tubes 102 and the drill pipe. When the multiple screen tubes 102 are lowered to the predetermined position, the tenon mechanism 5 is controlled to act, so as to achieve separation between the drill pipe and the universal ball seat 104, so as to facilitate the extraction of the drill pipe from the wellbore.

[0038] As a preferred solution, Figure 1 and Figure 2 As shown, the tenon mechanism 5 includes a drill pipe joint 601, a sleeve upper joint 602, a sleeve lower joint 603 and a claw mechanism 604, the drill pipe joint 601 is connected to the drill pipe, the sleeve upper joint 602 is connected to the universal ball seat 104, the sleeve lower joint 603 is arranged outside the sleeve upper joint 602 and connected to the sleeve upper joint 602, the outer wall of the sleeve lower joint 603 is provided with a plurality of slots 605, the claw mechanism 604 is arranged outside the sleeve lower joint 603 and connected to the drill pipe joint 601, the claw mechanism 604 can be engaged with the plurality of slots 605, and the claw mechanism 604 is used to lock or release the position of the sleeve upper joint 602 relative to the drill pipe joint 601. When the tenon mechanism 5 connects the drill rod and the universal ball seat 104, the claw mechanism 604 engages with the multiple slots 605 on the outer wall of the lower sleeve joint 603. Since the lower sleeve joint 603 is arranged outside the upper sleeve joint 602 and connected to the upper sleeve joint 602, the position of the upper sleeve joint 602 and the drill rod joint 601 are locked, thereby fixing the position of the drill rod and the upper sleeve joint 602. Since the upper sleeve joint 602 is connected to the universal ball seat 104, the connection between the drill rod and the universal ball seat 104 is completed. When the tenon mechanism 5 disengages the drill rod and the universal ball seat 104, the claw mechanism 604 is controlled to disengage from the multiple slots 605. At this time, when the drill rod moves away from the guide shoe 101, the drill rod drives the claw mechanism 604 to move away from the guide shoe 101 through the drill rod joint 601 until the claw mechanism 604 is out of contact with the lower joint 603 of the sliding sleeve, thereby realizing the separation of the drill rod and the universal ball seat 104.

[0039] As a preferred solution, Figure 1 and Figure 2As shown, the claw mechanism 604 includes a claw and a driving mechanism, the drill pipe joint 601 is inserted into the upper joint 602 of the sliding sleeve, the claw includes a connecting ring 702 and a plurality of claw arms 701, and the plurality of claw arms 701 have a certain elasticity. The connecting ring 702 is fixedly connected to the outer wall of the drill pipe joint 601, and the plurality of claw arms 701 are arranged on one side of the connecting ring 702. The lower joint 603 of the sliding sleeve is arranged in the plurality of claw arms 701, and the driving mechanism is connected to the plurality of claw arms 701. The driving mechanism is used to drive the claw arms 701 to be clamped into the clamping groove 605 to limit the movement of the upper joint 602 of the sliding sleeve relative to the upper joint of the drill pipe. When the tenon mechanism 5 connects the drill rod and the universal ball seat 104, the driving mechanism applies an inward squeezing force to the multiple claw arms 701, so that the multiple claw arms 701 are deformed inward until the claw arms 701 are stuck in the slots 605, and the claw arms 701 are used to limit the movement of the upper joint 602 of the sliding sleeve relative to the upper joint of the drill rod, thereby completing the connection between the drill rod and the universal ball seat 104. When the tenon mechanism 5 disengages the drill rod and the universal ball seat 104, the driving mechanism is controlled to disengage from the multiple claw arms 701, and the multiple claw arms 701 are restored under the action of their own elastic force, so that each claw arm 701 pops out of the slot 605 where it is located, thereby releasing the restriction on the movement of the upper joint 602 of the sliding sleeve relative to the upper joint of the drill rod.

[0040] As a preferred solution, Figure 1 and Figure 2 As shown, the driving mechanism includes a sleeve 801 and a hydraulic control circuit. The sleeve 801 is slidably connected to the outside of the sleeve lower joint 603 along its own axial direction. The multiple claw arms 701 are in contact with the inner wall of one end of the sleeve 801. The sleeve 801 is used to squeeze each claw arm 701 into a slot 605. A sealed cavity 802 is provided between the inner wall of the other end of the sleeve 801 and the outer wall of the sleeve lower joint 603. The hydraulic control circuit is connected to the sealed cavity 802. When the hydraulic control circuit introduces hydraulic oil into the sealed cavity 802, the hydraulic oil drives the sleeve 801 to move away from one end of the claw arm 701, so that the inner wall of the sleeve 801 is out of contact with the claw arm 701, thereby causing the claw arm 701 to escape from the slot 605. When the tenon mechanism 5 connects the drill rod and the universal ball seat 104, the inner wall of the sleeve 801 abuts against the plurality of claw arms 701, so that each claw arm 701 is squeezed into a slot 605 to limit the movement of the sleeve upper joint 602 relative to the drill rod upper joint. When the tenon mechanism 5 disengages the drill rod and the universal ball seat 104, the hydraulic control circuit is controlled to operate, and hydraulic oil is supplied to the sealing chamber 802 by the hydraulic control circuit. The hydraulic oil in the sealing chamber 802 pushes the sleeve 801 to move away from the claw arm 701, so that the inner wall of the sleeve 801 is disengaged from the claw arm 701, so that the claw arm 701 is disengaged from the slot 605, so as to release the restriction on the movement of the sleeve upper joint 602 relative to the drill rod upper joint.

[0041] As a preferred solution, Figure 1 and Figure 2 As shown, the side walls of the sleeve lower joint 603 and the sleeve 801 are both provided with pin holes along the radial direction of the sleeve 801, and a limit pin 901 is provided in the pin hole. When the hydraulic oil in the sealing chamber 802 reaches a certain pressure, the hydraulic oil drives the sleeve 801 to cut off the limit pin 901, and a limit retaining ring 902 is provided on the outer wall of the sleeve lower joint 603. The limit retaining ring 902 can abut against the end of the sleeve 801 away from the claw arm 701, and the limit retaining ring 902 is used to prevent the sleeve 801 from slipping off the sleeve lower joint 603.

[0042] As a preferred solution, Figure 1 and Figure 3 As shown, a ball head locking ring 106 is provided in the universal ball seat 104, and the ball head locking ring 106 is connected to one end of the universal ball seat 104 close to the universal ball head 105, and the ball head locking ring 106 abuts against the outer wall of the universal ball head 105, and the ball head locking ring 106 is used to limit the displacement of the universal ball head 105 relative to the universal ball seat 104.

[0043] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A high-curvature flexible ultra-short radius completion pipe string, comprising a guide shoe (101) and a plurality of screen tubes (102), wherein the plurality of screen tubes (102) are connected end to end, characterized in that: Also includes: A plurality of flexible short sections (103) are arranged alternately with the plurality of screen tubes (102), two adjacent screen tubes (102) are connected via a flexible short section (103), and each flexible short section (103) comprises a universal ball seat (104) and a universal ball head (105); The universal ball seat (104) is connected to a drill pipe or one of the screen tubes (102) used for well completion, and a first through hole (108) is provided in the universal ball seat (104); One end of the universal ball head (105) is hinged to the universal ball seat (104), and the other end of the universal ball head (105) is connected to another screen tube (102). A second through hole (109) is provided in the universal ball head (105), and the tube hole of the screen tube (102) is connected to the first through hole (108) and the second through hole (109); A tension locking joint (107) has one end connected to the last screen tube (102) and the other end connected to the guide shoe (101). The tension locking joint (107) is used to reduce stress between multiple screen tubes (102).

2. The high curvature flexible ultra-short radius completion pipe string according to claim 1, characterized in that: The tension locking joint (107) comprises a core shaft (201) and a guide shoe joint (202), one end of the core shaft (201) is connected to the end of the screen tube (102) away from the guide shoe (101), one end of the guide shoe joint (202) is connected to the guide shoe (101), the other end of the guide shoe joint (202) is provided with a step hole (203), the other end of the core shaft (201) is slidably connected in the step hole (203) along the axial direction of the step hole (203), the side wall of the step hole (203) is provided with a threaded hole along the radial direction of the core shaft (201), a locking nut stabilizing nail (204) is threadedly connected in the threaded hole, and the locking nut stabilizing nail (204) is pressed against the outer wall of the core shaft (201) to limit the movement of the core shaft (201) relative to the step hole (203).

3. The high curvature flexible ultra-short radius completion pipe string according to claim 2, characterized in that: A slip ring (301) is provided on the outer wall of one end of the core shaft (201) close to the step hole (203); the core shaft (201) is connected to the step hole (203) by sliding along the axial direction of the step hole (203) through the slip ring (301); a core shaft lock nut (302) is detachably connected to the step hole (203); the core shaft lock nut (302) is in contact with the slip ring (301); and the core shaft lock nut (302) is used to prevent the slip ring (301) from falling out of the step hole (203).

4. The high curvature flexible ultra-short radius completion string according to claim 3, characterized in that: A screen pipe joint (401) is provided at one end of the core shaft (201) away from the slip ring (301), and the core shaft (201) is detachably connected to one end of the screen pipe (102) away from the guide shoe (101) through the screen pipe joint (401). A pressure-relief gasket (402) is provided in the step hole (203), and the pressure-relief gasket (402) has a certain elasticity. The end of the core shaft (201) close to the guide shoe (101) can abut against the pressure-relief gasket (402), and the pressure-relief gasket (402) is used to apply an elastic force along the axial direction of the step hole (203) to the core shaft (201).

5. The high curvature flexible ultra-short radius completion string according to claim 1, characterized in that: A latch mechanism (5) is provided between the drill rod and the universal ball seat (104); one end of the latch mechanism (5) is connected to the drill rod, and the other end of the latch mechanism (5) is connected to the universal ball seat (104); the latch mechanism (5) is used to achieve connection or disconnection between the drill rod and the universal ball seat (104).

6. The high-curvature flexible ultra-short radius completion string according to claim 5, characterized in that: The latch mechanism (5) comprises a drill pipe joint (601), a sliding sleeve upper joint (602), a ball seat joint (606), a sliding sleeve lower joint (603) and a claw mechanism (604); the drill pipe joint (601) is connected to the drill pipe via the ball seat joint (606); the sliding sleeve upper joint (602) is connected to the universal ball seat (104); the sliding sleeve lower joint (603) is arranged outside the sliding sleeve upper joint (602) and connected to the sliding sleeve upper joint (602); a plurality of slots (605) are arranged on the outer wall of the sliding sleeve lower joint (603); the claw mechanism (604) is arranged outside the sliding sleeve lower joint (603) and connected to the drill pipe joint (601); the claw mechanism (604) can be engaged with the plurality of slots (605); and the claw mechanism (604) is used to lock or release the position of the sliding sleeve upper joint (602) relative to the drill pipe joint (601).

7. The high-curvature flexible ultra-short radius completion string according to claim 6, characterized in that: The clamping claw mechanism (604) comprises a clamping claw and a driving mechanism. The drill pipe joint (601) is inserted into the upper joint (602) of the sliding sleeve. The clamping claw comprises a connecting ring (702) and a plurality of clamping arms (701). The plurality of clamping arms (701) all have a certain elasticity. The connecting ring (702) is fixedly connected to the outer wall of the drill pipe joint (601). The plurality of clamping arms (701) are arranged on one side of the connecting ring (702). The lower joint (603) of the sliding sleeve is arranged in the plurality of clamping arms (701). The driving mechanism is connected to the plurality of clamping arms (701). The driving mechanism is used to drive the clamping arms (701) to clamp into the clamping groove (605) to limit the movement of the upper joint (602) of the sliding sleeve relative to the upper joint of the drill pipe.

8. The high-curvature flexible ultra-short radius completion string according to claim 7, characterized in that: The driving mechanism comprises a sleeve (801) and a hydraulic control circuit. The sleeve (801) is slidably connected to the outside of the sleeve lower joint (603) along its own axis. The plurality of claw arms (701) abut against the inner wall of one end of the sleeve (801). The sleeve (801) is used to squeeze each claw arm (701) into a slot (605). A sealing cavity (802) is provided between the inner wall of the other end of the sleeve (801) and the outer wall of the sleeve lower joint (603). The hydraulic control circuit is connected to the sealing cavity (802). When the hydraulic control circuit introduces hydraulic oil into the sealing cavity (802), the hydraulic oil drives the sleeve (801) to move away from one end of the claw arm (701), so that the inner wall of the sleeve (801) is out of contact with the claw arm (701), thereby causing the claw arm (701) to escape from the slot (605).

9. The high-curvature flexible ultra-short radius completion string according to claim 8, characterized in that: Pin holes are provided on the side walls of the lower sleeve joint (603) and the sleeve (801) along the radial direction of the sleeve (801), and a limit pin (901) is provided in the pin hole. When the hydraulic oil in the sealing chamber (802) reaches a certain pressure, the hydraulic oil drives the sleeve (801) to cut off the limit pin (901). A limit retaining ring (902) is provided on the outer wall of the lower sleeve joint (603). The limit retaining ring (902) can abut against one end of the sleeve (801) away from the claw arm (701), and the limit retaining ring (902) is used to prevent the sleeve (801) from slipping off the lower sleeve joint (603).

10. The high-curvature flexible ultra-short radius completion string according to claim 1, characterized in that: A ball head locking ring (106) is arranged inside the universal ball seat (104). The ball head locking ring (106) is connected to one end of the universal ball seat (104) close to the universal ball head (105). The ball head locking ring (106) abuts against the outer wall of the universal ball head (105). The ball head locking ring (106) is used to limit the displacement of the universal ball head (105) relative to the universal ball seat (104).

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