Packer, fracturing and fluid drainage integrated pipe column and using method of fracturing and fluid drainage integrated pipe column

Abstract

The invention relates to the technical field of petroleum and natural gas exploration and development, in particular to a packer, a fracturing and liquid drainage integrated tubular column and a using method, and aims to solve the problems that fracturing and liquid drainage operation needs to be separately constructed, the operation cost is high, and secondary pollution of a reservoir is caused. The packer comprises a central pipe, and a rubber sleeve unit, a first-stage hydraulic cylinder body, a second-stage hydraulic cylinder body, a ratchet piston, an upper cone and a bidirectional slip which are arranged on the central pipe in a sleeving manner; the first-stage hydraulic cylinder body and the second-stage hydraulic cylinder body move towards the rubber sleeve unit to extrude the rubber sleeve unit; the ratchet piston pushes the upper cone to enable the upper cone to push the bidirectional slip; the two-way slip is provided with two sections of anti-retreating teeth, and the locking directions of the two sections of anti-retreating teeth are opposite. The packer is anchored in two directions through the two-way slips, so that the rubber sleeve unit bears pressure in two directions, guarantee is provided for one-time operation of fracturing and liquid drainage operation, and the problems of high operation cost and secondary pollution of a reservoir caused by separate construction are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of oil and gas exploration and development, and particularly to a packer, a fracturing and liquid discharging integrated string and a using method thereof. Background Art

[0002] With the continuous deepening of oil and gas exploration and development, the reservoir depth is getting deeper and deeper. Deep reservoirs generally have characteristics such as high temperature and high fracture pressure. For oil and gas reservoirs with low porosity and low permeability characteristics, fracturing measures are required for transformation. Due to the water sensitivity of fracturing fluid, it is easy to damage the reservoir, and the fracturing fluid needs to be discharged from the wellbore in time after fracturing.

[0003] Hydraulic pump liquid discharging is to pump the working fluid from the tubing into the well by a ground power pump, and use the principle of generating negative pressure at the nozzle of the hydraulic pump core in the well to suck up the liquid at the bottom of the well, and then discharge it into the oil-casing annulus from the working barrel of the hydraulic pump, and finally return it to the ground. Hydraulic pump liquid discharging has the characteristics of fast liquid discharging speed and strong capacity. Timely liquid discharging can effectively reduce the damage of fracturing fluid to the reservoir.

[0004] Limited by the power of the ground power pump, the working barrel of the hydraulic pump is generally lowered to a depth of about 3000 meters during hydraulic pump liquid discharging. In the liquid discharging string, it is usually the practice to connect the sand-carrying cup and the packer in sequence under the working barrel of the hydraulic pump. When pulling out the string, if sand sticking or sand burying occurs, the working barrel of the hydraulic pump can be used as a circulation channel to achieve circulation and release of stuck, facilitating the pulling out of the string. When the packer is lowered to a shallow depth, the requirements for the temperature resistance grade and pressure-bearing grade of the packer for hydraulic pump liquid discharging are relatively low. During fracturing, in order to provide effective protection for the upper casing of the oil and gas layer, it is generally required that the packer be lowered to near the top of the oil and gas layer. The packer will be lowered deeper, and the requirements for the temperature resistance grade and pressure-bearing grade of the packer are higher. In addition, during hydraulic pump liquid discharging, the packer needs to maintain the sealing of the oil-casing annulus. The packer bears the liquid column pressure of the oil-casing annulus, that is, it bears the upper pressure difference, aiming to prevent the liquid sucked up from the bottom of the well from falling back to the bottom of the well again and circulating reciprocally, resulting in ineffective liquid discharging. While the fracturing packer generally bears the lower pressure difference. If the fracturing string is used as the hydraulic pump liquid discharging string, there will also be a situation where the distance between the packer and the working barrel of the hydraulic pump is too far. There is no circulation and release channel in the string. Once the string gets sand stuck or sand buried, the packer cannot be released, and the string will face the risk of being pulled out. To solve the above problems, the common practice in high-temperature and high-pressure oil and gas wells at present is to conduct blowout after fracturing, conduct well killing operation after the blowout liquid production is low, pull out the fracturing string in the well, and then re-lower the hydraulic pump liquid discharging string for liquid discharging and production measurement. This not only increases the operation cost, but also the well killing operation will cause secondary pollution to the reservoir, resulting in a decrease in production. That is, the existing fracturing and liquid discharging operations need to be constructed separately, resulting in high operation costs and secondary pollution of the reservoir. Summary of the Invention

[0005] The object of the present invention is to provide a packer, a fracturing and liquid discharging integrated pipe string and a using method, so as to solve the problems that fracturing and liquid discharging operations need to be carried out separately, resulting in high operation costs and secondary pollution of the reservoir.

[0006] To solve the above technical problems, the technical solution provided by the present invention lies in:

[0007] A packer includes a central pipe, and a rubber barrel unit, a first-stage liquid cylinder body, a second-stage liquid cylinder body, a ratchet piston, an upper cone and a two-way slip sleeve sleeved on the central pipe. The first-stage liquid cylinder body is connected to the second-stage liquid cylinder body. When the tubing is pressured, the first-stage liquid cylinder body and the second-stage liquid cylinder body move towards the rubber barrel unit to squeeze the rubber barrel unit, thereby causing the rubber barrel unit to expand to form a seal with the inner wall of the casing. At the same time, the ratchet piston is used to push the upper cone, and the upper cone is used to push the two-way slip sleeve to move radially along the central pipe and engage with the inner wall of the casing. Two anti-retreat teeth are provided on the two-way slip sleeve, and the locking directions of the two anti-retreat teeth are opposite to prevent movement along the axis of the central pipe with the casing.

[0008] Further, the packer further includes a connecting mandrel and a first piston. The connecting mandrel is sleeved on the central pipe, and the rubber barrel unit, the first-stage liquid cylinder body, the second-stage liquid cylinder body and the ratchet piston are sleeved on the connecting mandrel. The first piston is sleeved on the connecting mandrel and inserted into the first-stage liquid cylinder body. The connecting mandrel, the first piston and the first-stage liquid cylinder body enclose a first starting space. The ratchet piston is inserted into the second-stage liquid cylinder body, and the connecting mandrel, the ratchet piston and the second-stage liquid cylinder body enclose a second starting space. A slotted hole is provided on the side wall of the central pipe, and a liquid transmission hole is provided on the central pipe. The slotted hole is communicated with the liquid transmission hole, and two groups of liquid transmission holes are respectively communicated with the first starting space and the second starting space. Liquid enters the first starting space and the second starting space to push the first-stage liquid cylinder body, the second-stage liquid cylinder body and the ratchet piston to move along the axis of the central pipe.

[0009] Further, the packer further includes a lock sleeve and a first lock ring. The first lock ring is sleeved on the connecting mandrel and connected to the connecting mandrel. The lock sleeve is connected to the first piston and forms an annular groove, and the first lock ring is clamped in the annular groove.

[0010] Further, the packer further includes a lock ring seat, a ratchet lock ring, a lock ring retaining ring and an elastic retaining ring. The lock ring seat is sleeved on the ratchet piston and connected to the second-stage liquid cylinder body. The ratchet lock ring is sleeved on the ratchet piston and inserted into the lock ring seat. The lock ring retaining ring is sleeved on the ratchet piston and inserted into the lock ring seat to limit the ratchet lock ring. The elastic retaining ring is installed on the lock ring seat and arranged on the side of the lock ring retaining ring away from the ratchet lock ring to limit the lock ring retaining ring. Teeth corresponding to the ratchet piston are provided on the ratchet lock ring for locking the ratchet piston.

[0011] Further, the packer further includes a shear sleeve and a starting pin. The shear sleeve is sleeved on the ratchet piston and connected to the ratchet piston. The starting pin is inserted into both the shear sleeve and the lock ring seat at the same time.

[0012] Further, the packer further includes a slip sleeve, a return spring, a ratchet pawl, a lower cone, and a slip retaining ring; the slip sleeve is sleeved on the upper cone and connected to the upper cone through a starting pin; the return spring is connected to the bi-directional slips to apply a pulling force to the bi-directional slips, causing the bi-directional slips to move towards the central pipe; the ratchet pawl is sleeved on the central pipe, one end is connected to the connecting mandrel, and the other end is threadedly connected to the lower cone; the lower cone is sleeved on the central pipe and the ratchet pawl and connected to the central pipe, and the upper cone and the lower cone are respectively inserted into the bi-directional slips from both ends; the slip retaining ring is sleeved on the lower cone and inserted into the slip sleeve, and the slip retaining ring is connected to the slip sleeve and abuts against the lower cone.

[0013] Further, one end of the ratchet pawl connected to the lower cone is provided with a split structure so that the ratchet pawl can contract radially, thereby separating the threaded connection between the ratchet pawl and the lower cone;

[0014] The central pipe is provided with an unseating groove. During unseating, as the central pipe moves, when the ratchet pawl is located at the unseating groove, it can contract radially.

[0015] Further, the packer further includes a fixed joint and a limit ring. The fixed joint is sleeved on the central pipe and arranged at one end of the rubber barrel unit away from the first-stage cylinder body. The connecting mandrel is inserted into the fixed joint and connected to the fixed joint. The limit ring is clamped in the annular groove formed by the connecting mandrel and the fixed joint; a limit groove is opened on the central pipe, and the limit ring is arranged in the limit groove and can move along the axis of the central pipe; during unseating, the central pipe moves upward so that the limit groove abuts against the limit ring, thereby driving the limit ring and the fixed joint to move the fixed joint away from the rubber barrel unit; a positioning boss is arranged on the connecting mandrel. During unseating, as the fixed joint moves, the positioning boss can abut against the second-stage cylinder body and drive the second-stage cylinder body to move, thereby driving the upper cone away from the bi-directional slips, so that the bi-directional slips retract under the action of the return spring.

[0016] On the other hand, the present invention provides a fracturing and fluid discharging integrated pipe string, which includes the above-mentioned packer, and further includes a setting nipple, a hydraulic anchor, a normally closed circulation valve, a safety joint, and a hydraulic pump working barrel. The setting nipple, the packer, the hydraulic anchor, the normally closed circulation valve, the safety joint, and the hydraulic pump working barrel are connected in sequence from bottom to top.

[0017] On the third aspect of the present invention, a method for using a fracturing and fluid discharging integrated pipe string is provided. The fracturing and fluid discharging integrated pipe string described above is adopted, and the method includes the following steps:

[0018] Lower the fracturing and fluid discharging integrated pipe string: According to the pipe string structure, lower each component in sequence and install the wellhead;

[0019] Packer setting: Insert a soluble ball, apply pressure to the tubing to make the first-stage cylinder body and the second-stage cylinder body move upward synchronously to squeeze the rubber barrel unit, and the ratchet piston moves downward to push the upper cone, and then push the bi-directional slips to make them bite with the inner wall of the casing;

[0020] Fracturing operation: After the packer is verified to be sealed properly, install a fracturing wellhead and conduct a fracturing operation. The fracturing fluid is injected into the formation through the setting nipple;

[0021] Drainage operation: After the fracturing operation is completed, insert a hydraulic pump core into the hydraulic pump working barrel from the tubing, and pump power fluid from the tubing to perform the hydraulic pump drainage operation.

[0022] Based on the above technical solutions, the technical effects that the present invention can achieve are as follows:

[0023] The packer provided by the present invention includes a central pipe and a rubber barrel unit, a first-stage cylinder body, a second-stage cylinder body, a ratchet piston, an upper cone, and bi-directional slips sleeved on the central pipe. The first-stage cylinder body is connected to the second-stage cylinder body; applying pressure to the tubing makes the first-stage cylinder body and the second-stage cylinder body move towards the rubber barrel unit to squeeze the rubber barrel unit, and then the rubber barrel unit expands to form a seal with the inner wall of the casing; at the same time, the ratchet piston pushes the upper cone so that the upper cone pushes the bi-directional slips to move radially along the central pipe and bite with the inner wall of the casing; two anti-backlash teeth are provided on the bi-directional slips, and the locking directions of the two anti-backlash teeth are opposite to prevent movement along the axis of the central pipe with the casing.

[0024] The packer provided by the present invention realizes reliable setting through two-stage cylinder bodies and performs two-way anchoring through bi-directional slips, ensuring that the packer can withstand pressures in two axial directions, and further enabling the rubber barrel unit to bear pressure in two directions, providing a guarantee for the fracturing and drainage operations to be carried out at one time, and avoiding the problems of high operation costs and secondary reservoir pollution caused by separate construction. Description of the Drawings

[0025] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0026] Figure 1 It is a schematic structural diagram of the packer provided by the embodiment of the present invention;

[0027] Figure 2 It is a schematic structural diagram of the upper section of the packer;

[0028] Figure 3 It is a schematic structural diagram of the middle section of the packer;

[0029] Figure 4 It is a schematic structural diagram of the lower section of the packer;

[0030] Figure 5 is Figure 2 an enlarged view of part A in

[0031] Figure 6 is Figure 3 an enlarged view of part B in

[0032] Figure 7 It is a schematic structural diagram of the thread of the ratchet claw;

[0033] Figure 8 It is a schematic structural diagram of the integrated fracturing and fluid drainage string provided by the embodiment of the present invention.

[0034] Icon: 100 - setting nipple; 200 - packer; 300 - hydraulic anchor; 400 - normally closed circulation valve; 500 - safety joint; 600 - hydraulic pump working barrel; 1 - upper joint; 2 - central tube; 3 - fixed joint; 4 - limit ring; 5 - connecting mandrel; 6 - pressure ring; 7 - rubber cylinder unit; 8 - first - stage cylinder body; 9 - lock sleeve; 10 - first lock ring; 11 - first piston; 12 - second - stage cylinder body; 13 - ratchet piston; 14 - lock ring seat; 15 - ratchet lock ring; 16 - lock ring retaining ring; 17 - circlip; 18 - starting pin; 19 - shear sleeve; 20 - upper cone; 21 - slip sleeve; 22 - bi - directional slips; 23 - return spring; 24 - ratchet claw; 25 - slip retaining ring; 26 - lower cone; 27 - releasing pin; 28 - lower joint; 101 - slotted seam; 102 - fluid transmission hole; 103 - first starting space; 104 - second starting space; 105 - releasing groove; 106 - limit groove; 107 - positioning boss. Detailed implementation manners

[0035] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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 some, but not all, of the embodiments of the present invention. Usually, the components of the embodiments of the present invention described and illustrated herein can be arranged and designed in various different configurations.

[0036] Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0037] The following will describe in detail some embodiments of the present invention with reference to the accompanying drawings. Without conflict, the following embodiments and the features in the embodiments may be combined with each other.

[0038] Currently, the common practice for high-temperature and high-pressure oil and gas wells is to conduct a blowdown after fracturing. After the blowdown fluid production is low, a well killing operation is carried out, the fracturing string in the well is pulled out, and then a hydraulic pump drainage string is re-lowered for drainage and production testing. This not only increases the operation cost, but also the well killing operation will cause secondary pollution to the reservoir, resulting in a decrease in production. That is, the existing fracturing and drainage operations need to be carried out separately, which has problems such as high operation cost and secondary pollution to the reservoir.

[0039] In view of this, the present invention provides a packer, which includes a central pipe 2 and a rubber barrel unit 7, a first-stage cylinder body 8, a second-stage cylinder body 12, a ratchet piston 13, an upper cone 20, and a bi-directional slip 22 sleeved on the central pipe 2. The first-stage cylinder body 8 is connected to the second-stage cylinder body 12; when the tubing is pressured, the first-stage cylinder body 8 and the second-stage cylinder body 12 move towards the rubber barrel unit 7 to squeeze the rubber barrel unit 7, so that the rubber barrel unit 7 expands to form a seal with the inner wall of the casing; at the same time, the ratchet piston 13 pushes the upper cone 20, so that the upper cone 20 pushes the bi-directional slip 22 to move radially along the central pipe 2 and engage with the inner wall of the casing; two anti-retreat teeth are provided on the bi-directional slip 22, and the locking directions of the two anti-retreat teeth are opposite to prevent the movement along the axis of the central pipe 2 with the casing.

[0040] The packer provided by the present invention realizes reliable setting through two-stage cylinder bodies and performs bi-directional anchoring through the bi-directional slip 22, ensuring that the packer can withstand pressures in two axial directions, and further enabling the rubber barrel unit 7 to bear pressures in two directions, providing a guarantee for the one-time construction of fracturing and drainage operations, and avoiding the problems of high operation cost and secondary pollution to the reservoir caused by separate construction.

[0041] The following will combine Figures 1 - 7 to describe in detail the structure and shape of the packer provided in this embodiment:

[0042] In an alternative solution of this embodiment, the packer includes an upper joint 1, a central pipe 2, a lower joint 28, and a fixed joint 3, a pressure ring 6, a rubber barrel unit 7, a pressure ring 6, a first-stage cylinder body 8, a second-stage cylinder body 12, a lock ring seat 14, a shear sleeve 19, an upper cone 20, a bi-directional slip 22, and a lower cone 26 sleeved on the central pipe 2 from top to bottom in sequence. In addition, a connecting mandrel 5 sleeved on the central pipe 2 is also included, and the fixed joint 3, the pressure ring 6, the rubber barrel unit 7, the pressure ring 6, the first-stage cylinder body 8, the second-stage cylinder body 12, the lock ring seat 14, the shear sleeve 19, and the upper cone 20 are all sleeved on the connecting mandrel 5. Specifically, both ends of the central pipe 2 are threadedly connected to the upper joint 1 and the lower joint 28 respectively.

[0043] In this embodiment, the cartridge unit 7 includes an upper cartridge, a middle cartridge, and a lower cartridge. As Figure 2 shown, the cartridges are separated by retaining rings. The upper and lower cartridges can protect the middle cartridge from being scratched. When the upper and lower cartridges are damaged and fail, the middle cartridge can still maintain a sealed state with the inner wall of the casing. In addition, after the upper and lower cartridges are deformed by extrusion, it helps to maintain the deformed state of the middle cartridge. Moreover, guide rings are provided at both ends of the upper and lower cartridges facing away from the middle cartridge. The cross-section of the guide ring is provided with an inclined surface for guiding the upper and lower cartridges to approach the middle cartridge when being extruded to facilitate the increase in diameter, so as to achieve a reliable seal.

[0044] In this embodiment, to ensure adaptation to the high-temperature and high-pressure environment, the upper cartridge, the middle cartridge, and the lower cartridge are all made of tetrapropyl fluoride rubber.

[0045] In this embodiment, pressure rings 6 are provided at both the upper and lower ends of the cartridge unit 7. The upper pressure ring 6 is threadedly connected to the fixed joint 3, and the lower pressure ring 6 is threadedly connected to the first-stage cylinder body 8. The other end of the first-stage cylinder body 8 is threadedly connected to the second-stage cylinder body 12. Specifically, as Figure 2 、 Figure 3 shown, the packer further includes a lock sleeve 9, a first lock ring 10, and a first piston 11. The first piston 11 is sleeved on the connecting mandrel 5 and inserted into the first-stage cylinder body 8. The connecting mandrel 5, the first piston 11, and the first-stage cylinder body 8 enclose a first starting space 103. The first lock ring 10 is sleeved on the connecting mandrel 5 and connected to the connecting mandrel 5. The lock sleeve 9 is threadedly connected to the first piston 11 to form an annular groove, and the first lock ring 10 is clamped in the annular groove, so that the first piston 11 is fixedly connected to the connecting mandrel 5, that is, an annular groove is provided on the connecting mandrel 5 for installing the first lock ring 10. At the same time, a slotted hole 101 is provided on the side wall of the central tube 2, and a liquid transmission hole 102 is provided on the central tube 2. The slotted hole 101 is communicated with the liquid transmission hole 102, and the liquid transmission hole 102 is communicated with the first starting space 103.

[0046] Similarly, the packer further includes a ratchet piston 13. The ratchet piston 13 is inserted into the second-stage cylinder body 12 and sleeved on the connecting mandrel 5. The connecting mandrel 5, the ratchet piston 13, and the second-stage cylinder body 12 enclose a second starting space 104. Corresponding slotted holes 101 are provided on the side wall of the central tube 2, and corresponding liquid transmission holes 102 are provided on the central tube 2 to communicate the central tube 2 with the second starting space 104.

[0047] In this embodiment, corresponding to the first starting space 103 and the second starting space 104, two sets of slotted seams 101 and liquid transmission holes 102 are provided. Specifically, each set of slotted seams 101 has 8 pieces, which are evenly distributed annularly around the axis of the central pipe 2. When the tubing is under pressure, the liquid enters the first starting space 103 and the second starting space 104 through the slotted seams 101 and the liquid transmission holes 102 to drive the first-stage cylinder block 8, the second-stage cylinder block 12 and the ratchet piston 13 to move along the axis of the central pipe 2.

[0048] In this embodiment, to maintain the set state, the packer further includes a lock ring seat 14, a ratchet lock ring 15, a lock ring retaining ring 16 and an elastic retaining ring 17. The ratchet lock ring 15 is provided with teeth corresponding to the ratchet piston 13 for locking the ratchet piston 13, as Figure 6 described. Specifically, the lock ring seat 14 is sleeved on the ratchet piston 13 and is threadedly connected to the second-stage cylinder block 12. The ratchet lock ring 15 is sleeved on the ratchet piston 13 and is inserted into the lock ring seat 14. The lock ring retaining ring 16 is sleeved on the ratchet piston 13 and is inserted into the lock ring seat 14 to limit the ratchet lock ring 15. The elastic retaining ring 17 is installed on the lock ring seat 14 and is arranged on the side of the lock ring retaining ring 16 away from the ratchet lock ring 15 to limit the lock ring retaining ring 16. The ratchet lock ring 15 and the ratchet piston 13 are provided with teeth to achieve one-way locking, and its structure can refer to Figure 7 . To facilitate the locking of the ratchet piston 13 and the ratchet lock ring 15, a slotted seam 101 can be made on the ratchet lock ring 15 to form a C-shaped ring, which is convenient for the ratchet piston 13 to move downward and lock with the ratchet lock ring 15.

[0049] In this embodiment, there is a certain moving distance between the second-stage cylinder block 12 and the first piston 11. This moving distance is set to 22 mm to meet the requirement that the rubber cylinder unit 7 has a compression distance of 18 mm under a compression force of 15 T.

[0050] In this embodiment, the packer further includes a starting pin 18, as Figure 3 shown. The shear sleeve 19 is sleeved on the ratchet piston 13 and is threadedly connected to the ratchet piston 13. The starting pin 18 is inserted into the shear sleeve 19 and the lock ring seat 14 at the same time to connect the two.

[0051] In this embodiment, the other end of the shear sleeve 19 is sleeved on the lower cone 26 and is threadedly connected to the lower cone 26, as Figure 3 shown. When the ratchet piston 13 moves downward, it can drive the lower cone 26 to move through the shear sleeve 19, and then the lower cone 26 drives the bi-directional slips 22 to bite with the inner wall of the casing.

[0052] Specifically, the packer further includes a slip sleeve 21, a return spring 23, a ratchet claw 24 and a slip retaining ring 25. As Figure 4As shown in the figure, the ratchet pawl 24 is sleeved on the central tube 2, one end is threadedly connected to the connecting mandrel 5, and the other end is threadedly connected to the lower cone 26; the slip sleeve 21 is sleeved on the ratchet pawl 24, the upper cone 20 and the lower cone 26, and the slip retainer ring 25 is sleeved on the lower cone 26 and inserted into the slip sleeve 21. The slip retainer ring 25 is threadedly connected to the slip sleeve 21 and abuts against the lower cone 26. Two anti-retreat teeth are provided on the bi-directional slip 22, and the locking directions of the two anti-retreat teeth are opposite to prevent the movement along the axis of the central tube 2 with the casing. The bi-directional slip 22 is installed on the slip sleeve 21, and the return spring 23 is connected to the bi-directional slip 22 to apply a pulling force to the bi-directional slip 22, so that the bi-directional slip 22 moves towards the direction close to the central tube 2. At the same time, the slip sleeve 21 and the upper cone 20 are connected by the starting pin 18.

[0053] In this embodiment, one end of the ratchet pawl 24 connected to the lower cone 26 is set as a split structure so that the ratchet pawl 24 can contract radially, so that the threaded connection between the ratchet pawl 24 and the lower cone 26 can be separated. Specifically, the shape of the teeth on the ratchet pawl 24 is as Figure 7 shown. The split structure is to cut the middle and lower sections of the ratchet pawl 24 along the direction parallel to the axis of the ratchet pawl 24 to facilitate radial contraction. To ensure the contraction of the ratchet pawl 24, a release groove 105 is provided on the central tube 2. During release, the central tube 2 moves upward. When the ratchet pawl 24 moves to the release groove 105, there is a space for radial contraction.

[0054] In this embodiment, a positioning boss 107 is provided on the connecting mandrel 5. The positioning boss 107 can abut against the second-stage cylinder body 12. When the connecting mandrel 5 moves upward, the positioning boss 107 abuts against and drives the second-stage cylinder body 12 to move upward, and then drives the upper cone 20 to move upward to reset the bi-directional slip 22.

[0055] In this embodiment, the packer further includes a release pin 27, and the release pin 27 is inserted into both the central tube 2 and the lower cone 26 at the same time to connect the two.

[0056] In this embodiment, the packer further includes a limit ring 4, and the limit ring 4 is clamped in the annular groove formed by the connecting mandrel 5 and the fixed joint 3, as Figure 2 shown. A limit groove 106 is opened on the central tube 2. The limit ring 4 is arranged in the limit groove 106 and can move along the axis of the central tube 2; during release, the central tube 2 moves upward so that the lower end of the limit groove 106 abuts against the limit ring 4, and then drives the limit ring 4 and the fixed joint 3 so that the fixed joint 3 moves away from the rubber cylinder unit 7.

[0057] The working process of the packer provided in this embodiment is as follows:

[0058] When setting the seal, a soluble ball is put into the oil pipe to close the lower end of the center pipe 2. The oil pipe is pressurized to 18MPa to cut off the start pins 18 at the lock ring seat 14 and the slip sleeve 21. Then the pressure is continued, and the liquid enters the first start space 103 and the second start space 104 through the slit 101 and the liquid transfer hole 102, thereby pushing the first-stage liquid cylinder body 8 and the second-stage liquid cylinder body 12 upward to drive the pressure ring 6, so that the pressure ring 6 squeezes the rubber cylinder unit 7, and then the rubber cylinder unit 7 expands and forms a seal with the inner wall of the casing. At the same time, the ratchet piston 13 moves downward to push the upper cone 20 to further insert the two-way slip 22, so that the two-way slip 22 is pushed out of the slip sleeve 21 and anchored into the inner wall of the casing for bite, completing the setting. In addition, the soluble ball is made of magnesium-aluminum alloy to ensure its solubility for subsequent construction.

[0059] It should be noted that after the sealing is completed, the teeth on the ratchet piston 13 mesh with the teeth on the ratchet locking ring 15, thereby locking the ratchet piston 13 and the second-stage liquid cylinder body 12 in one direction, preventing the ratchet piston 13 from approaching the rubber cylinder unit 7 and the second-stage liquid cylinder body 12 from moving away from the rubber cylinder unit 7, thereby preventing the rubber cylinder unit 7 from losing support and causing sealing failure.

[0060] When unsealing, the pipe column is lifted to drive the center pipe 2 upward. Due to the anchoring effect of the bidirectional slip 22, the center pipe 2 and the lower cone 26 move relative to each other and the unsealing pin 27 is sheared off. The pipe column is lifted continuously, and the unsealing groove 105 and the limiting groove 106 move upward due to the upward movement of the center pipe 2. When the unsealing groove 105 moves to the petal structure of the ratchet claw 24, the ratchet claw 24 contracts radially under its own elasticity to disengage the threaded connection between the ratchet claw 24 and the lower cone 26; when the lower end of the limiting groove 106 abuts against the limiting ring 4, the center pipe 2 drives the limiting ring 4 to synchronously drive the fixed joint 3 and the pressure ring 6 connected to the fixed joint 3 upward, and the upper end of the rubber cylinder unit 7 loses the limit and resets under the action of its own elasticity to achieve unsealing. At this time, the connecting core shaft 5 and the ratchet claw 24 move upward synchronously with the fixed joint 3, thereby preventing the ratchet claw 24 from reconnecting with the lower cone 26. Continue to lift the pipe column. As the fixed joint 3 and the connecting core shaft 5 move upward, the positioning boss 107 abuts against the second-stage liquid cylinder body 12 and drives the second-stage liquid cylinder body 12 upward. At this time, the second-stage liquid cylinder body 12 is connected to the ratchet piston 13 through the ratchet lock ring 15, and the ratchet piston 13 is connected to the shear sleeve 19 and the upper cone 20 in sequence, thereby driving the upper cone 20 to move. At this time, the upper cone 20 and the lower cone 26 are both away from the two-way slip 22. The two-way slip 22 loses support and retracts under the pulling force of the reset spring 23, completing the separation from the inner wall of the casing, thereby completing the unsealing.

[0061] The packer provided in this embodiment squeezes the rubber barrel unit 7 jointly by the first-stage cylinder body 8 and the second-stage cylinder body 12 to ensure sufficient squeezing force, thereby ensuring the sealing reliability. The cooperation of the ratchet lock ring 15 and the ratchet piston 13 prevents the relative movement between the ratchet piston 13 and the second-stage cylinder body 12 after setting, which may cause the rubber barrel unit 7 to lose the squeezing of the first-stage cylinder body 8 and the second-stage cylinder body 12, and the upper cone 20 to move away from the two-way slip 22, resulting in sealing failure and anchoring failure, thus ensuring the reliability of setting. Through the cooperation of the positioning boss 107, the unsealing groove 105, and the limiting groove 106 with the second-stage cylinder body 12, the limiting ring 4, and the ratchet pawl 24 respectively, an orderly action is achieved to ensure unsealing, and reliable unsealing is realized. Especially, the split structure of the ratchet pawl 24 and the connection structure between the ratchet pawl 24 and the lower cone 26 enable the lower cone 26 and the ratchet pawl 24 to maintain reliable connection during setting and reliable unlocking during unsealing, ensuring the smooth progress of setting and unsealing.

[0062] The tubing is pressured to make the first-stage cylinder body 8 and the second-stage cylinder body 12 move towards the rubber barrel unit 7 to squeeze the rubber barrel unit 7, thereby causing the rubber barrel unit 7 to expand to form a seal with the inner wall of the casing; at the same time, the ratchet piston 13 is pushed to make the upper cone 20 push the two-way slip 22 to move radially along the central pipe 2 and bite with the inner wall of the casing;

[0063] Based on the packer provided in this embodiment, a fracturing and liquid discharging integrated pipe string is proposed, which includes the above-mentioned packer 200, and also includes a setting nipple 100, a hydraulic anchor 300, a normally closed circulation valve 400, a safety joint 500, and a hydraulic pump working barrel 600. The setting nipple 100, the packer 200, the hydraulic anchor 300, the normally closed circulation valve 400, the safety joint 500, and the hydraulic pump working barrel 600 are connected in sequence from bottom to top, as Figure 8 shown. Specifically, the normally closed circulation valve 400 can only be opened by dropping a steel ball from the wellhead to realize the connection between the oil casing; the hydraulic pump working barrel 600 is opened by applying pressure to the annulus between the oil casing. After opening, the hydraulic pump core can be dropped from the wellhead for hydraulic pump liquid discharging. When closing, it is blocked by dropping the closing pump core from the wellhead. The opening and closing of the hydraulic pump working barrel 600 are prior arts and will not be elaborated here; the setting nipple 100 includes a body and an inner sliding sleeve arranged inside the body. The lower end of the body is provided with a bell mouth. The inner sliding sleeve is made of a soluble magnesium-aluminum alloy material and is fixed inside the body by shear pins.

[0064] In this embodiment, the hydraulic pump working barrel 600 is connected by a certain number of tubing strings, enabling the packer 200 to be lowered deeper to meet the requirement of protecting the upper casing of the oil and gas layer during fracturing. The length of the tubing string should be such that the setting depth of the packer 200 is close to the top depth of the reservoir, and the position of the packer 200 is above the top of the reservoir. Especially when using combined casing completion, the setting depth of the packer 200 is below the position of the liner hanger, which can effectively protect the liner hanger and the casing above it.

[0065] When the tubing string is sand-buried or sand-locked, steel balls and the special hydraulic pump core are successively dropped from the wellhead. After the steel balls fall into the sleeve of the normally closed circulation valve 400 and the closing pump core drops to the hydraulic pump working barrel 600, the outlet at the hydraulic pump working barrel 600 is blocked by the closing pump core. Subsequently, the tubing string is pressured up, and the pressure is transmitted to the sleeve of the normally closed circulation valve 400, causing the sleeve to move downward, thereby opening the normally closed circulation valve 400. After the normally closed circulation valve 400 is opened, the tubing string is connected to the casing, and normal reverse circulation sand washing is carried out from the tubing string. After the sand lock is released, the packer is normally released. When the tubing string returns to its original suspended weight, it indicates that the packer has been released, and the tubing string in the well can be pulled out.

[0066] Based on the fracturing and fluid drainage integrated tubing string provided in this embodiment, a method for using the fracturing and fluid drainage integrated tubing string is proposed, including the following steps:

[0067] Collect the basic data of the construction well: mainly including the completion casing size, wall thickness, casing steel grade, casing coupling depth data, and cementing quality.

[0068] Calculate and check the tensile strength of the tubing string.

[0069] Determine the setting position of the packer: According to the tensile strength of the tubing string, the top depth of the reservoir, the casing coupling depth data, and the cementing quality, and under the condition of meeting the tensile strength requirement of the tubing string, preferably set the packer at a depth above the top depth of the fracturing interval in a well section with good cementing quality and avoid the casing coupling.

[0070] Lower the fracturing and fluid drainage integrated tubing string: According to the tubing string structure, successively lower each component and install the wellhead;

[0071] Packer setting: Insert a soluble ball. The soluble ball falls into the inner sliding sleeve of the setting nipple 100. The tubing is pressured to 18 MPa. The starting pin 18 is sheared off, and the packer is activated. The tubing continues to be pressured, and then the first-stage cylinder body 8 and the second-stage cylinder body 12 move upward together, pushing the pressure ring 6 to compress the rubber barrel unit 7. At the same time, relative movement occurs between the ratchet piston 13 and the ratchet lock ring 15. The ratchet piston 13 moves downward and pushes the upper cone 20 to push the bi-directional slip 22 out of the slip sleeve 21, and the bi-directional slip 22 anchors into the inner wall of the casing. When the pressure reaches 32 MPa, the soluble ball and the inner sliding sleeve of the setting nipple 100 are knocked off and fall to the bottom of the well. At the same time, the rubber barrel unit 7 is completely compressed, the ratchet piston 13 and the ratchet lock ring 15 stop moving and are locked, and the packer setting is completed.

[0072] Packer sealing inspection: Open the casing. The tubing is pressured to 36 MPa and stabilized for 10 minutes. The pressure drop is less than 0.5 MPa, and there is no backflow from the casing. The sealing inspection is qualified.

[0073] Fracturing operation: After the packer sealing inspection is qualified, install the fracturing wellhead and conduct the fracturing operation. The fracturing fluid is injected into the formation through the setting nipple 100.

[0074] Liquid discharging operation: After the fracturing operation is completed, when hydraulic pump liquid discharging is required, pressure is applied from the annulus between the tubing and the casing to open the working barrel 600 of the hydraulic pump. Then, insert the pump core of the hydraulic pump from the tubing. Relying on the surface power pump, power liquid is pumped into the tubing to conduct the hydraulic pump liquid discharging operation.

[0075] After the hydraulic pump liquid discharging is completed, under normal circumstances, lift the tubing string to release the packer and pull out the integrated tubing string. If the tubing string is sand stuck or sand buried and the packer cannot be released, then successively insert steel balls from the wellhead and close the pump core. The tubing is pressured to open the normally closed circulation valve 400, and normal circulation sand washing and stuck releasing are carried out. After the stuck is released, lift the tubing string to release the packer, and when the tubing string restores the original suspended weight, pull out the tubing string in the well.

[0076] Finally, it should be noted that: The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: They can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A packer, characterized in that, It includes a central tube (2), and a rubber barrel unit (7), a first-stage hydraulic cylinder body (8), a second-stage hydraulic cylinder body (12), a ratchet piston (13), an upper cone (20) and a bi-directional slip (22) sleeved on the central tube (2). The first-stage hydraulic cylinder body (8) is connected to the second-stage hydraulic cylinder body (12). When the tubing is pressured, the first-stage hydraulic cylinder body (8) and the second-stage hydraulic cylinder body (12) move towards the rubber barrel unit (7) to squeeze the rubber barrel unit (7), thereby causing the rubber barrel unit (7) to expand to form a seal with the inner wall of the casing. At the same time, the ratchet piston (13) pushes the upper cone (20) so that the upper cone (20) pushes the bi-directional slip (22) to move radially along the central tube (2) and engage with the inner wall of the casing. Two anti-retreat teeth are provided on the bi-directional slip (22), and the locking directions of the two anti-retreat teeth are opposite to prevent movement along the axis of the central tube (2) with the casing.

2. The packer according to claim 1, characterized in that, It further includes a connecting mandrel (5) and a first piston (11). The connecting mandrel (5) is sleeved on the central tube (2), and the rubber barrel unit (7), the first-stage hydraulic cylinder body (8), the second-stage hydraulic cylinder body (12) and the ratchet piston (13) are sleeved on the connecting mandrel (5). The first piston (11) is sleeved on the connecting mandrel (5) and inserted into the first-stage hydraulic cylinder body (8). The connecting mandrel (5), the first piston (11) and the first-stage hydraulic cylinder body (8) enclose a first starting space (103). The ratchet piston (13) is inserted into the second-stage hydraulic cylinder body (12), and the connecting mandrel (5), the ratchet piston (13) and the second-stage hydraulic cylinder body (12) enclose a second starting space (104). A slotted seam (101) is provided on the side wall of the central tube (2), and a liquid transmission hole (102) is provided on the central tube (2). The slotted seam (101) is communicated with the liquid transmission hole (102), and two groups of the liquid transmission holes (102) are respectively communicated with the first starting space (103) and the second starting space (104). Liquid enters the first starting space (103) and the second starting space (104) to push the first-stage hydraulic cylinder body (8), the second-stage hydraulic cylinder body (12) and the ratchet piston (13) to move along the axis of the central tube (2).

3. The packer according to claim 2, wherein It further includes a lock sleeve (9) and a first lock ring (10). The first lock ring (10) is sleeved on the connecting mandrel (5) and connected to the connecting mandrel (5). The lock sleeve (9) is connected to the first piston (11) to form an annular groove, and the first lock ring (10) is clamped in the annular groove.

4. The packer according to claim 3, characterized in that, It further includes a lock ring seat (14), a ratchet lock ring (15), a lock ring retaining ring (16) and an elastic retaining ring (17). The lock ring seat (14) is sleeved on the ratchet piston (13) and connected to the second-stage hydraulic cylinder body (12). The ratchet lock ring (15) is sleeved on the ratchet piston (13) and inserted into the lock ring seat (14). The lock ring retaining ring (16) is sleeved on the ratchet piston (13) and inserted into the lock ring seat (14) to limit the position of the ratchet lock ring (15), and the circlip (17) is installed on the lock ring seat (14) and arranged on the side of the lock ring retaining ring (16) away from the ratchet lock ring (15) to limit the position of the lock ring retaining ring (16); The ratchet lock ring (15) is provided with teeth corresponding to the ratchet piston (13) for locking the ratchet piston (13).

5. The packer according to claim 4, wherein, It further includes a shear sleeve (19) and a starting pin (18); The shear sleeve (19) is sleeved on the ratchet piston (13) and connected to the ratchet piston (13), and the starting pin (18) is inserted into both the shear sleeve (19) and the lock ring seat (14).

6. The packer according to claim 5, wherein It further includes a slip bushing (21), a return spring (23), a ratchet pawl (24), a lower cone (26) and a slip retaining ring (25); The slip bushing (21) is sleeved on the upper cone (20) and connected to the upper cone (20) through the starting pin (18); The return spring (23) is connected to the bi-directional slip (22) to apply a pulling force to the bi-directional slip (22), causing the bi-directional slip (22) to move towards the center pipe (2); The ratchet pawl (24) is sleeved on the center pipe (2), one end is connected to the connecting mandrel (5), and the other end is threadedly connected to the lower cone (26); The lower cone (26) is sleeved on the center pipe (2) and the ratchet pawl (24) and connected to the center pipe (2), and the upper cone (20) and the lower cone (26) are respectively inserted into the bi-directional slip (22) from both ends; The slip retaining ring (25) is sleeved on the lower cone (26) and inserted into the slip bushing (21), and the slip retaining ring (25) is connected to the slip bushing (21) and abuts against the lower cone (26).

7. The packer according to claim 6, characterized in that, One end of the ratchet pawl (24) connected to the lower cone (26) is provided with a split structure so that the ratchet pawl (24) can contract radially, thereby separating the threaded connection between the ratchet pawl (24) and the lower cone (26); The center pipe (2) is provided with a releasing groove (105). During releasing, as the center pipe (2) moves, when the ratchet pawl (24) is located at the releasing groove (105), it can contract radially.

8. The packer according to claim 7, characterized in that, It further includes a fixed joint (3) and a limit ring (4). The fixed joint (3) is sleeved on the center pipe (2) and arranged at one end of the rubber cylinder unit (7) away from the first-stage cylinder block (8). The connecting mandrel (5) is inserted into the fixed joint (3) and connected to the fixed joint (3), and the limit ring (4) is clamped in the annular groove formed by the connecting mandrel (5) and the fixed joint (3); The central tube (2) is provided with a limiting groove (106), and the limiting ring (4) is arranged in the limiting groove (106) and can move along the axis of the central tube (2); when unsealing, the central tube (2) moves upward so that the limiting groove (106) abuts against the limiting ring (4), thereby driving the limiting ring (4) and the fixed joint (3) so that the fixed joint (3) is away from the rubber cylinder unit (7); A positioning boss (107) is provided on the connecting core shaft (5). When unsealed, as the fixed joint (3) moves, the positioning boss (107) can abut against the second-stage liquid cylinder body (12) and drive the second-stage liquid cylinder body (12) to move, thereby driving the upper cone (20) away from the two-way cava (22), so that the two-way cava (22) retracts under the action of the return spring (23).

9. A fracturing and fluid drainage integrated pipe string, characterized in that, The invention comprises a packer as described in any one of claims 1 to 8, and further comprises a sealing nipple (100), a hydraulic anchor (300), a normally closed circulation valve (400), a safety joint (500) and a hydraulic pump working cylinder (600), wherein the sealing nipple (100), the packer, the hydraulic anchor (300), the normally closed circulation valve (400), the safety joint (500) and the hydraulic pump working cylinder (600) are connected in sequence from bottom to top.

10. A method for using an integrated fracturing and fluid drainage string, which uses the integrated fracturing and fluid drainage string as described in claim 9, and is characterized in that, The steps include: Lower the integrated fracturing and drainage string: according to the string structure, lower each component in turn and install the wellhead; Packer setting: the soluble ball is put in, and the oil pipe is pressurized to make the first-stage liquid cylinder (8) and the second-stage liquid cylinder (12) move upward synchronously to squeeze the rubber cylinder unit (7), and the ratchet piston (13) moves downward to push the upper cone (20), thereby pushing the bidirectional slip (22) to engage with the inner wall of the casing; Fracturing construction: after the packer is inspected and sealed, the fracturing wellhead is installed to carry out fracturing construction, and the fracturing fluid is injected into the formation through the setting sub (100); Fluid discharge construction: After the fracturing construction is completed, the hydraulic pump core is inserted from the oil pipe into the hydraulic pump working cylinder (600), and power fluid is pumped into the oil pipe to perform hydraulic pump fluid discharge operation.

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