Infinite-stage oil pipe fracturing pipe column process for vertical well and implementation method of infinite-stage oil pipe fracturing pipe column process

Abstract

The invention provides a vertical well infinite oil pipe fracturing pipe column technology and an implementation method, and belongs to the technical field of oil field well completion fracturing devices. A well killing valve is located at the uppermost end, and a hydraulic anchor and a packer are sequentially arranged below the well killing valve; an infinite-stage fracturing sliding sleeve, a safety release joint and a packer are sequentially arranged between the two target layers; the infinite fracturing sliding sleeves are arranged at all underground target layers; the infinite-order fracturing sliding sleeve comprises an opening tool assembly for controlling opening of the infinite-order fracturing sliding sleeve. The telescopic pipe is arranged between the packer of each target layer and the infinite fracturing sliding sleeve of the next target layer; a setting ball seat is arranged above a target layer closest to an artificial well bottom, and the setting ball seat can provide a pressure building condition during setting. According to the method, the problem that the partial pressure stage number and the fracturing scale of an existing vertical well partial pressure pipe column process technology are limited is solved, meanwhile, the setting and unsetting operation difficulty of the partial pressure pipe column is reduced, the sand burying prevention capacity of the pipe column is achieved, and the safety of the partial pressure pipe column is improved.

Description

Technical Field

[0001] The invention relates to the technical field of oilfield completion fracturing devices, and in particular to a vertical well infinite-stage oil pipe fracturing string process and an implementation method thereof. Background Art

[0002] For vertical well stratified fracturing, the packer + sliding sleeve stratified fracturing string process is a process with a long application time and rich string technology and downhole tools. Especially for repeated fracturing in old areas and old wells, due to the long service time of the casing, casing damage and leakage are prominent, and the casing cannot be used as a fracturing string. The combination of tubing with packers and sliding sleeves is almost the only feasible solution.

[0003] Although this type of process has a variety of column processes to choose from, there are generally the following common problems that are difficult to overcome:

[0004] 1. Limitation of the number of pressure-dividing stages. For vertical well pressure-dividing tubing, no matter how the tubing structure changes, a fracturing sleeve must be used as a fluid passage between the tubing and the formation during fracturing. At present, the fracturing sleeve adopts a step-by-step ball-throwing method, and the corresponding balls are thrown in the order of the sleeve diameter from small to large to open the fracturing sleeves at different layers. Since the size of the oil tubing operating in the oil casing is originally very small and the radial size is very valuable, this method can only be divided into a limited number of fracturing stages (for the commonly used 139.7mm specification oil casing, generally no more than 3 levels). In addition, the inner diameter of the first and second level sleeves is restricted by the radial size (wellbore inner diameter), which is usually small and cannot be the same as the inner diameter of the top sleeve.

[0005] 2. Impact on fracturing scale. As mentioned above, due to the influence of the working principle of the fracturing sleeve, the inner diameter of the sleeve at the bottom is very small in the limited pressure stage. During the fracturing operation, the increase in displacement will generate a higher throttling pressure, resulting in an increase in the operating pump pressure, which not only affects the project safety, but also leads to more energy waste; at the same operating displacement, the liquid flow velocity flowing through the thinner sleeve will increase significantly, eroding the downhole tools and oil layer casing, which will not only affect the safety of the pipe string, but also cause irreversible damage to the oil layer casing.

[0006] 3. Impact on operational safety. The fracturing string faces a series of problems that affect operational safety before and after the fracturing operation, mainly including: whether the string is reliably sealed; whether the tool erosion is serious during the fracturing process, whether the layer change is smooth and safe; whether it can be unsealed smoothly after fracturing, and whether it will be buried by sand.

[0007] At present, the vertical well split-pressure string process cannot achieve unlimited-stage fracturing, and generally adopts a string structure with an expansion packer or a combination of multiple types of packers. The expansion packer requires continuous liquid flow to complete the setting, and it is impossible to set the packer before the operation. It is impossible to know whether the string setting is reliable before the operation. In addition, when using this type of packer for fracturing operations, due to the existence of throttling, the liquid outlet velocity is high, which is easy to cause irreversible erosion damage to the oil layer casing; the string structure with a combination of multiple types of packers, such as a mechanical packer and a hydraulic packer, has a complex string structure due to different setting methods, and the setting and unsealing operation methods are different, which not only makes it difficult to set and unseal, but also the downhole accessories such as safety joints cannot adapt to the structural characteristics of the two types of packers at the same time. The string is complex and the safety risk is high.

[0008] The existing technology has at least the following deficiencies:

[0009] 1. The vertical well pressure-dividing string technology has limited pressure-dividing levels and fracturing scale;

[0010] 2. It is difficult to unseal the pressure column;

[0011] 3. The pipe string does not have the ability to prevent sand burial, and the safety of the pressure-dividing pipe string is low. Summary of the invention

[0012] In order to solve the problems existing in the prior art, the present invention provides a vertical well infinite-stage oil pipe fracturing string process, comprising: a well killing valve, a telescopic pipe, a hydraulic anchor, a packer, an infinite-stage fracturing sleeve, a safety release joint and a sealing ball seat; the well killing valve is located at the uppermost end, and a hydraulic anchor and a packer are sequentially arranged between the bottom of the well killing valve and the top of the first downhole target layer; the hydraulic anchor is anchored on the inner wall of the casing; an infinite-stage fracturing sleeve, a safety release joint and a packer are sequentially arranged between each downhole target layer and the next downhole target layer; the infinite-stage fracturing sleeve, a safety release joint and a packer are sequentially arranged The fracturing sleeve is arranged at each downhole target layer to provide a fluid flow channel during stratified fracturing; the infinite-stage fracturing sleeve includes an opening tool assembly for controlling the opening of the infinite-stage fracturing sleeve, and the safety release joint can achieve shear release when the pipe string is stuck; the telescopic tube is arranged between the packer of each target layer and the infinite-stage fracturing sleeve of the next target layer, and the telescopic tube is also arranged between the well-killing valve and the hydraulic anchor; a sealing ball seat is arranged above the target layer closest to the bottom of the artificial well, and the sealing ball seat can provide pressure holding conditions during sealing. The present invention solves the problem of limited pressure stages and fracturing scale in the existing vertical well pressure-sharing tubing technology, while reducing the difficulty of pressure-sharing tubing seat and release operation, and has the ability to prevent tubing from sand burial, thereby improving the safety of the pressure-sharing tubing.

[0013] The present invention provides a vertical well infinite-stage oil pipe fracturing string process, wherein the vertical well infinite-stage oil pipe fracturing string comprises: a well killing valve, a telescopic pipe, a hydraulic anchor, a packer, an infinite-stage fracturing sliding sleeve, a safety release joint and a setting ball seat;

[0014] The well-killing valve is located at the uppermost end, and a hydraulic anchor and a packer are sequentially arranged between the lower part of the well-killing valve and the upper part of the first downhole target layer; the hydraulic anchor is anchored on the inner wall of the casing;

[0015] An infinite-stage fracturing sleeve, a safety release joint and a packer are sequentially arranged between each downhole target layer and the next downhole target layer; the infinite-stage fracturing sleeve is arranged at each downhole target layer to provide a fluid flow channel during layered fracturing; the infinite-stage fracturing sleeve includes an opening tool assembly for controlling the opening of the infinite-stage fracturing sleeve, and the safety release joint can realize shear release when the pipe string is stuck;

[0016] The telescopic pipe is arranged between the packer of each target layer and the infinite-stage fracturing sleeve of the next target layer, and the telescopic pipe is also arranged between the well-killing valve and the hydraulic anchor;

[0017] A sealing ball seat is arranged above the target layer closest to the bottom of the artificial well, and the sealing ball seat can provide a pressure holding condition during sealing.

[0018] Before the tubing is raised, the well killing valve is opened to circulate and kill the well to meet the well control needs; the expansion pipe is used to provide a part of the tubing extension to meet the corresponding tubing process requirements; during fracturing, the hydraulic anchor is firmly anchored on the casing wall to provide an anchor point for the tubing; the packer is used to isolate the target layer downhole; the infinite-stage fracturing sleeve is used to provide a fluid flow channel during stratified fracturing; the safety release joint is used to achieve shear release when the tubing is stuck; the sealing ball seat is used to provide the pressure holding condition during sealing, and the ball seat is knocked out after the sealing is completed to provide the first-stage fracturing channel.

[0019] Preferably, the packer is a hydraulic compression packer.

[0020] Preferably, the well-killing valve comprises a well-killing valve body, an inner sleeve assembly and an opening ball, the inner sleeve assembly is located inside the well-killing valve body, the opening ball is located inside the well-killing valve body, the inner sleeve assembly can slide along the inner wall of the well-killing valve body, and the opening ball can slide down along the inside of the inner sleeve assembly.

[0021] Preferably, the well-killing valve body includes an upper joint of the well-killing valve body, a well-killing valve body anti-loosening screw and a lower joint of the well-killing valve body; a liquid outlet hole is opened in the middle above the upper joint of the well-killing valve body, the upper joint of the well-killing valve body and the lower joint of the well-killing valve body are connected by threaded connection, and are fastened by the well-killing valve body anti-loosening screw.

[0022] Preferably, the inner sleeve assembly comprises an inner sleeve of a well-killing valve, a sealing ring of the well-killing valve and an opening shear pin. The upper end of the inner sleeve of the well-killing valve has a sloped step, which is fixed in a predetermined closed position by the opening shear pin. The sealing ring of the well-killing valve is sleeved on the outside of the inner sleeve of the well-killing valve.

[0023] Preferably, the slope of the step at the upper end of the sliding sleeve in the well killing valve is less than 25 degrees. Only in this way can the placement and passage of the infinite-stage fracturing sliding sleeve opening tool be avoided during the layer changing operation in the later tubing process.

[0024] Preferably, the telescopic tube includes a telescopic tube body component, a movable component, a telescopic tube accessory and a starting component. The movable component is arranged inside the telescopic tube body component. The movable component and the telescopic tube body component have a reserved stroke for relative movement to realize a column length compensation function. The telescopic tube accessory is arranged at one end inside the telescopic tube body component and is used to connect the telescopic tube body component and set a seal. The starting component is embedded in the side wall of the other end of the telescopic tube body component and is connected to the movable component. The starting component controls whether the telescopic tube body component and the movable component are movable or not.

[0025] Preferably, the telescopic tube body assembly comprises a telescopic tube upper joint, an extension tube, a telescopic tube body, a telescopic tube outer tube and a telescopic tube protective cover; wherein the telescopic tube upper joint, the extension tube, the telescopic tube body and the telescopic tube outer tube are connected by threaded connection, a liquid-passing hole is provided at the upper end of the telescopic tube body, and a locking hole is provided at the lower end of the telescopic tube body; a thread is provided at the upper end of the telescopic tube protective cover and is connected to the telescopic tube body; the telescopic tube outer tube and the telescopic tube protective cover are connected to the telescopic tube body through threads.

[0026] Preferably, the movable component comprises a limiting cap and a telescopic tube center tube, a groove is provided at the lower end of the telescopic tube center tube, and the limiting cap and the telescopic tube center tube are connected as a whole through a threaded connection.

[0027] Preferably, the telescopic tube accessories include a telescopic tube sealing ring and a telescopic tube anti-loosening screw, the telescopic tube sealing ring is sleeved on the outside of the extension tube and the telescopic tube center tube, and the telescopic tube anti-loosening screw connects the telescopic tube upper joint and the extension tube.

[0028] Preferably, the starting assembly includes a starting piston, a starting shear pin, a starting shear ring and a steel ball, the starting piston is arranged in a reserved space between the telescopic tube body and the telescopic tube outer tube, the starting shear pin and the starting shear ring are arranged at one end of the starting piston, the starting shear pin is embedded in the side wall of the telescopic tube outer tube, the starting shear ring is connected to the starting shear pin and is arranged between the telescopic tube body and the telescopic tube outer tube, a part of the steel ball is located in the groove at the lower end of the telescopic tube center tube, and the other part of the steel ball is located in the locking hole at the lower end of the telescopic tube body.

[0029] Preferably, the packer is a hydraulic compression packer, including a packer upper joint, a packer center tube, a sealing shear pin, an upper pressure cap, a packer sealing ring, a sealing unit, a liner, a packer clamp, an upper cone, a packer outer tube, a locking ring, an anchoring mechanism, a lower cone, a packer lower joint, a packer anti-drop screw and an anti-seating shear pin; the packer upper joint and the packer center tube are connected to the packer lower joint, the packer sealing ring is sleeved on the packer center tube, the upper part of the liner is connected to the upper pressure cap, the packer center tube is provided with a plurality of liquid holes, the packer center tube and the liner both have grooves, and the packer clamp is clamped in the grooves of the packer center tube and the liner; the sealing unit It is connected with the outer tube of the packer to form a sealed whole; the upper cone is connected to the lower cone and is located in the outer tube of the packer; the upper cone is a piston structure, and the lower cone is connected to the lower end of the liner; the unsealing shear pin is installed in the shear pin hole at the upper end of the upper pressure cap, and is positioned with the groove of the center tube of the packer; the anti-drop screw is fixed in the screw hole at the lower part of the upper cone, and the upper part of the anti-drop screw moves in the hole groove on the anchoring mechanism; the anti-sealing shear pin is installed in the shear pin hole at the lower end of the outer tube of the packer, and is positioned with the groove on the lower cone; the locking ring is installed between the outer tube of the packer and the upper cone to ensure that the outer tube of the packer and the upper cone can only move in one direction.

[0030] Preferably, the center tube of the packer is connected to the lower joint of the packer by threaded connection, and the upper part of the liner is connected to the upper pressure cap by threaded connection; a plurality of fluid holes are opened on the side wall of the center tube of the packer, and a groove is provided on the upper part of the side wall of the center tube of the packer; the lower end of the liner is an elastic claw structure, and the middle part of the liner is provided with a groove and a fluid hole; the packer retaining ring is an open C-type elastic ring.

[0031] Preferably, the sealing unit comprises a rubber cylinder piston, a rubber cylinder and a spacer ring, the rubber cylinder has a plurality of grooves, the spacer ring is arranged in the grooves of the rubber cylinder, and the rubber cylinder piston squeezes the rubber cylinder and the spacer ring to form a sealing unit.

[0032] Preferably, the lower end of the rubber cylinder piston is a threaded structure, which is connected to the outer tube of the packer through the threaded structure. The lower end of the liner has a step, and the lower end of the lower cone has a groove inside. The groove inside the lower end of the lower cone matches the step at the lower end of the liner to achieve connection and positioning.

[0033] Preferably, the anchoring mechanism comprises a slip, a spring and a slip frame; the slip and the spring are mounted on the slip frame, the spring is arranged between two slips, the slip frame has a hole groove, and the upper part of the anti-drop screw moves in the hole groove on the slip frame.

[0034] Preferably, the locking ring is an open C-shaped elastic ring with a thread on one side and a one-way tooth on the other side.

[0035] Preferably, the infinite-stage fracturing sleeve comprises an infinite-stage fracturing sleeve body component, an infinite-stage fracturing sleeve accessory and an opening tool component. The opening tool component is embedded in the side wall of the infinite-stage fracturing sleeve body component and connected to the infinite-stage fracturing sleeve accessory. The opening tool component controls whether the infinite-stage fracturing sleeve body component and the infinite-stage fracturing sleeve accessory are active or not.

[0036] Preferably, the infinite-stage fracturing sleeve body assembly comprises an infinite-stage fracturing sleeve upper joint, an infinite-stage fracturing sleeve body, an infinite-stage fracturing sleeve shear pin, an infinite-stage fracturing sleeve inner sleeve, an infinite-stage fracturing sleeve clamping ring and an infinite-stage fracturing sleeve lower joint; the infinite-stage fracturing sleeve upper joint has a slope inside, and is connected to the infinite-stage fracturing sleeve body and the infinite-stage fracturing sleeve lower joint by threads; the infinite-stage fracturing sleeve inner sleeve is pre-placed at a predetermined position on the infinite-stage fracturing sleeve body by the infinite-stage fracturing sleeve shear pin; the infinite-stage fracturing sleeve clamping ring is sleeved outside the infinite-stage fracturing sleeve inner sleeve to prevent the infinite-stage fracturing sleeve inner sleeve from moving in the opposite direction.

[0037] Preferably, the infinite-stage fracturing sleeve clamp ring is a C-shaped elastic open ring.

[0038] Preferably, the opening tool assembly includes: an upper pumping ball, an infinite-stage fracturing sleeve sealing ring, an upper ball seat, an opening tool body, a lower pumping ball and a lower ball seat; the upper ball seat and the lower ball seat are provided with sealing grooves, the infinite-stage fracturing sleeve sealing ring is installed in the sealing groove, and the upper ball seat and the lower ball seat are connected to the opening tool body; the opening tool body is a sleeve with a step, the right end face of the step of the opening tool body is consistent with the lower end of the groove of the inner sleeve of the infinite-stage fracturing sleeve, and the upper joint of the infinite-stage fracturing sleeve has a slope inside.

[0039] Preferably, the slope of the slope inside the upper joint of the infinite-stage fracturing sliding sleeve is less than 25 degrees.

[0040] Preferably, the upper ball seat and the lower ball seat are connected to the opening tool body by screws; the opening tool body is a hollow metal flexible sleeve with steps.

[0041] Preferably, the safety release joint includes a safety release upper joint, a safety release outer cylinder, a safety release lower joint, a safety release sealing ring and a safety release shear nail. The safety release upper joint has a slope inside, and the safety release upper joint is connected to the safety release outer cylinder as a whole; the safety release upper joint is connected to the safety release lower joint through the safety release shear nail.

[0042] Preferably, the safety release shear nail is installed in the threaded hole at the lower end of the safety release outer tube; the safety release upper joint and the safety release outer tube are connected as a whole through a threaded buckle.

[0043] The present invention provides a method for implementing the above-mentioned vertical well infinite-stage oil pipe fracturing string process, comprising the following steps:

[0044] Fracturing string entering the well: after well cleaning, well clearing and wall scraping preparations are completed, the vertical well infinite-stage oil fracturing string is connected, and then the vertical well infinite-stage oil fracturing string is lowered into the predetermined position according to the depth of the target layer, and the wellhead device is set;

[0045] Packer setting: a setting ball is put in, and it is allowed to settle freely or be pumped to the setting ball seat. At this time, a dead cavity is formed in the tubing string. The wellhead pump truck pumps the pressure to the preset pressure P0 to complete the setting of the packer downhole. Then the setting ball is knocked out to achieve communication between the tubing string and the formation.

[0046] fracture:

[0047] First stage of fracturing: inject fracturing fluid, which flows out from the tail end of the pipe string into the formation to complete the first stage of fracturing. The working pressure during fracturing is set to P;

[0048] During the fracturing process, the telescopic tube will reach the working pressure P1 and enter the working state;

[0049] Layer-changing fracturing: the opening tool assembly is put into the wellhead, the pump is sent to the next level, the pressure is built up to the opening pressure P2 of the infinite-stage fracturing sleeve, the infinite-stage fracturing sleeve is opened, and the current layer is fracturing; the changing fracturing is repeated to achieve fracturing of all levels;

[0050] Lifting the tubing string load: a ball matching the well-killing valve is dropped from the wellhead, and naturally sinks to the well-killing valve. When the pressure of the well-killing valve reaches P3, the well-killing valve is opened, and the well is cycled to the preset qualified standard; the tubing string load is lifted to the preset unsealing load F0, the downhole packer is unsealed, and the whole well tubing string is lifted;

[0051] Release and salvage: In case of sand burial of downhole tools and pipe jam, the pipe load is lifted to the preset release load F1, the safety release joint is cut off, the upper pipe is lifted out, and then sand flushing and salvage are carried out step by step.

[0052] Preferably, in the process of implementing the vertical well infinite-stage oil tubing fracturing string process, the parameters are set as follows:

[0053] Packer setting and releasing pressure P0 < fracturing pump pressure P;

[0054] Infinite-stage fracturing sleeve opening pressure P1 <P;

[0055] Well killing valve opening pressure P2 < fracturing pump pressure P;

[0056] Packer setting and releasing pressure P0 < telescopic opening pressure P3 < fracturing pump pressure P;

[0057] The fracturing pump pressure P is the maximum design pressure that the tubing string can withstand;

[0058] Unsealing load F0 < releasing load F1.

[0059] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0060] (1) The present invention solves the problem of limited pressure levels in the existing gradual ball-casting grading by adopting an infinite-stage fracturing sleeve; at the same time, the fracturing sleeve adopted is of large diameter and equal diameter, without throttling (or with extremely small throttling effect), which can effectively improve the operation pump pressure, solve the problem of limited fracturing scale, and solve the problem of limited pressure levels and fracturing scale in the existing vertical well pressure-dividing pipe string process technology;

[0061] (2) The present invention adopts a hydraulic expansion tube installed under the packer. When the pipe string is lifted to unseal, the expansion tube can provide an effective movable unseal space, so that the packer can be unsealed step by step, reducing the difficulty of the pressure-dividing pipe string seat unseal operation;

[0062] (3) The present invention adopts a safe release joint, which can be released and then the sand can be washed out in case of sand burial accident, thereby having the ability to prevent the pipe column from being buried in sand and improving the safety of the pressure-dividing pipe column. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] Figure 1 This is a schematic diagram of a vertical well infinite-stage pressure-dividing string structure according to an embodiment of the present invention; the string schematic diagram and tool symbols are drawn according to SY / T5373; all guide lines point to the uppermost end of the tool rather than the middle;

[0064] Figure 2 This is a schematic diagram of the structure of a well-killing valve in a ball-seated state according to an embodiment of the present invention;

[0065] Figure 3 It is a schematic diagram of the structure of a well-killing valve in a well-entering state according to an embodiment of the present invention;

[0066] Figure 4 A schematic diagram of a well-killing valve in an open state according to an embodiment of the present invention;

[0067] Figure 5 This is a schematic diagram of the telescopic pipe structure in a state of being assembled into a well according to an embodiment of the present invention;

[0068] Figure 6 A schematic diagram of the working principle of a starting assembly of a telescopic tube according to an embodiment of the present invention;

[0069] Figure 7 is a schematic diagram of a telescopic tube in a working state (i.e., a compensation state) according to an embodiment of the present invention;

[0070] Figure 8 (a) and (b) together constitute a schematic diagram of the structure of a hydraulic compression packer in an assembled well state according to an embodiment of the present invention. (a) and (b) are a whole and are respectively parts of the schematic diagram of the structure of a hydraulic compression packer in an assembled well state according to an embodiment of the present invention.

[0071] Fig. 9 (a) and (b) together constitute a schematic diagram of the structure of a hydraulic compression packer in a set state according to an embodiment of the present invention. (a) and (b) are a whole and are respectively a part of the schematic diagram of the structure of a hydraulic compression packer in a set state according to an embodiment of the present invention.

[0072] Fig.10 (a) and (b) together constitute a schematic diagram of the structure of a hydraulic compression packer in an unsealed state according to an embodiment of the present invention. (a) and (b) are a whole and are respectively parts of the schematic diagram of the structure of a hydraulic compression packer in an unsealed state according to an embodiment of the present invention.

[0073] Fig.11 This is a schematic diagram of the infinite-stage fracturing sleeve structure in a well-entering state according to an embodiment of the present invention;

[0074] Fig.12 (a) is a structural diagram of an inner sleeve of an infinite-stage fracturing sleeve according to an embodiment of the present invention, and (b) is a partial enlarged diagram of part B in (a);

[0075] Fig.13 It is a schematic structural diagram of an opening tool assembly of an infinite-stage fracturing sleeve according to an embodiment of the present invention;

[0076] Fig.14(a) is a structural diagram of the opening tool body of an infinite-stage fracturing sleeve according to an embodiment of the present invention; (b) is a cross-sectional view taken along the AA direction in (a); (c) is a partial enlarged view of the B position in (a); (d) is a cross-sectional view taken along the CC direction in (a);

[0077] Fig.15 It is a schematic diagram when the opening tool assembly does not match the infinite-stage fracturing sliding sleeve;

[0078] Fig.16 It is a schematic diagram of an opening tool assembly according to an embodiment of the present invention matching with an infinite-stage fracturing sliding sleeve;

[0079] Fig.17 A schematic diagram of an opening tool assembly according to an embodiment of the present invention opening an infinite-stage fracturing sleeve;

[0080] Fig.18 This is a schematic diagram of the structure of a safety release joint according to an embodiment of the present invention;

[0081] Fig.19 This is a schematic diagram of the structure of the safety release joint out of the well according to an embodiment of the present invention;

[0082] Fig. 20 This is a schematic diagram of the structure of the downhole part of a safety release joint according to an embodiment of the present invention;

[0083] Fig.21 The present invention is a flowchart of a method for implementing a vertical well infinite-stage oil tubing fracturing string process according to an embodiment of the present invention.

[0084] In the figure, 1, well-killing valve; 2, telescopic pipe; 3, hydraulic anchor; 4, packer; 5, infinite fracturing sleeve; 6, safety release joint; 7, sealing ball seat; 1-a, well-killing valve body; 1-b, inner sleeve assembly; 1-c, opening ball; 1-a1, well-killing valve body upper joint, 1-a2, well-killing valve body anti-loosening screw; 1-a3, well-killing valve body lower joint; 1-b1, well-killing valve inner sleeve; 1-b2, well-killing valve sealing ring; 1-b3, opening shear nail; 2-a, telescopic pipe body assembly; 2-b, movable assembly; 2-c, telescopic pipe accessories; 2-d, starting assembly; 2-a1, telescopic pipe joint; 2-a2, extension pipe; 2-a3, telescopic pipe body; 2-a4, telescopic pipe outer tube; 2-a5, telescopic pipe protective cover; 2-b1, limit cap; 2-b2, telescopic pipe center tube; 2-c1, telescopic pipe sealing ring; 2-c2, telescopic pipe anti-loosening screw; 2-d1, start piston; 2-d2, start shear nail; 2-d3, start shear ring; 2-d4, steel ball; 4-1, packer joint; 4-2, packer center tube; 4-3, unpacking shear nail; 4-4, upper pressure cap; 4-5, packer sealing ring; 4-6, liner; 4-7, rubber cylinder; 4-8, spacer ring; 4- 9, rubber cylinder piston; 4-10, packer clamp ring, 4-11, upper cone; 4-12, packer outer cylinder; 4-13, lock ring, 4-14, slip frame; 4-15, spring; 4-16, slip; 4-17, lower cone; 4-18, packer lower joint; 4-19, packer anti-drop screw; 4-20, anti-seating shear nail; 5-a, infinite-stage fracturing sleeve body assembly, 5-b, infinite-stage fracturing sleeve accessories; 5-c, opening tool assembly; 5-a1, infinite-stage fracturing sleeve upper joint; 5-a2, infinite-stage fracturing sleeve body; 5-a3, infinite-stage fracturing sleeve shear nail; 5- a4, infinite-stage fracturing sleeve inner sleeve; 5-a5, infinite-stage fracturing sleeve retaining ring; 5-a6, infinite-stage fracturing sleeve lower joint; 5-b1, infinite-stage fracturing sleeve accessory anti-loosening screw; 5-b2, infinite-stage fracturing sleeve accessory sealing ring; 5-c1, upper pumping ball; 5-c2, infinite-stage fracturing sleeve sealing ring; 5-c3, upper ball seat; 5-c4, opening tool body; 5-c5, lower pumping ball; 5-c6, lower ball seat; 6-1, safety release upper joint; 6-2, safety release outer cylinder; 6-3, safety release lower joint; 6-4, safety release sealing ring; 6-5, safety release shear nail. DETAILED DESCRIPTION

[0085] The specific implementation modes of the present invention are described in detail below in conjunction with the accompanying drawings.

[0086] The present invention provides a vertical well infinite-stage oil pipe fracturing string process, wherein the vertical well infinite-stage oil pipe fracturing string comprises: a well killing valve 1, a telescopic pipe 2, a hydraulic anchor 3, a packer 4, an infinite-stage fracturing sliding sleeve 5, a safety release joint 6 and a setting ball seat 7;

[0087] The well-killing valve 1 is located at the uppermost end, and a hydraulic anchor 3 and a packer 4 are sequentially arranged between the bottom of the well-killing valve 1 and the top of the first downhole target layer; the hydraulic anchor 3 is anchored on the inner wall of the casing;

[0088] An infinite-stage fracturing sleeve 5, a safety release joint 6 and a packer 4 are sequentially arranged between each downhole target layer and the next downhole target layer; the infinite-stage fracturing sleeve 5 is arranged at each downhole target layer to provide a fluid flow channel during layered fracturing; the infinite-stage fracturing sleeve 5 includes an opening tool component 5-c for controlling the opening of the infinite-stage fracturing sleeve 5, and the safety release joint 6 can achieve shear release when the pipe string is stuck;

[0089] The telescopic pipe 2 is arranged between the packer 4 of each target layer and the infinite-stage fracturing sleeve 5 of the next target layer, and the telescopic pipe 2 is also arranged between the well-killing valve 1 and the hydraulic anchor 3;

[0090] A sealing ball seat 7 is arranged above the target layer closest to the bottom of the artificial well, and the sealing ball seat 7 can provide a pressure holding condition during sealing.

[0091] According to a specific embodiment of the present invention, the packer 4 is a hydraulic compression packer.

[0092] According to a specific embodiment of the present invention, the wellbore valve 1 includes a wellbore valve body 1-a, an inner sleeve assembly 1-b and an opening ball 1-c, the inner sleeve assembly 1-b is located inside the wellbore valve body 1-a, the opening ball 1-c is located inside the wellbore valve body 1-a, the inner sleeve assembly 1-b can slide along the inner wall of the wellbore valve body 1-a, and the opening ball 1-c can slide along the inside of the inner sleeve assembly 1-b.

[0093] According to a specific embodiment of the present invention, the well-killing valve body 1-a includes an upper joint 1-a1 of the well-killing valve body, an anti-loosening screw 1-a2 of the well-killing valve body and a lower joint 1-a3 of the well-killing valve body; a liquid outlet is opened in the middle part above the upper joint 1-a1 of the well-killing valve body, and the upper joint 1-a1 of the well-killing valve body and the lower joint 1-a3 of the well-killing valve body are connected by threaded connection and are fastened by the anti-loosening screw 1-a2 of the well-killing valve body.

[0094] According to a specific embodiment of the present invention, the inner sleeve assembly 1-b includes an inner sleeve 1-b1 of a well-killing valve, a sealing ring 1-b2 of a well-killing valve and an opening shear pin 1-b3. The upper end of the inner sleeve 1-b1 of the well-killing valve has a step with a slope, which is fixed in a predetermined closed position by the opening shear pin 1-b3. The sealing ring 1-b2 of the well-killing valve is sleeved on the outside of the inner sleeve 1-b1 of the well-killing valve.

[0095] According to a specific embodiment of the present invention, the slope of the step at the upper end of the sliding sleeve 1-b1 in the well killing valve is less than 25 degrees. Only in this way can the placement and passage of the infinite-stage fracturing sliding sleeve opening tool be avoided during the layer changing operation in the later tubing string process.

[0096] Use the opening shear nail 1-b3 to fix it in the predetermined closing position. Figure 3 ), the outlet hole of the wellbore valve is closed and communication between the tubing and the casing annulus cannot be achieved.

[0097] When it is necessary to lift the tubing string, the opening ball 1-c is put in, and the opening ball 1-c slides down to the sloped step at the upper end of the inner sleeve, and a dead cavity is formed in the tubing string. When the pressure is held up to the opening pressure of the well-killing valve, the opening shear pin 1-b3 is sheared off, and the inner sleeve descends to the step inside the lower joint, and the well-killing valve is opened, so that the tubing string is connected with the oil casing annulus, and the conditions for circulating well-killing are met.

[0098] The diameter of the well-killing valve is denoted as D1.

[0099] According to a specific embodiment of the present invention, the telescopic tube 2 includes a telescopic tube body component 2-a, a movable component 2-b, a telescopic tube attachment 2-c and a starting component 2-d. The movable component 2-b is arranged inside the telescopic tube body component 2-a. The movable component 2-b and the telescopic tube body component 2-a have a reserved stroke for relative movement to realize a column length compensation function. The telescopic tube attachment 2-c is arranged at one end inside the telescopic tube body component 2-a, and is used to connect the telescopic tube body component 2-a and set a seal. The starting component 2-d is embedded in the side wall of the other end of the telescopic tube body component 2-a and is connected to the movable component 2-b. The starting component 2-d controls whether the telescopic tube body component 2-a and the movable component 2-b are active or not.

[0100] According to a specific embodiment of the present invention, the telescopic tube body assembly 2-a includes a telescopic tube upper joint 2-a1, an extension tube head 2-a2, a telescopic tube body 2-a3, a telescopic tube outer tube 2-a4 and a telescopic tube protective cover 2-a5; wherein, the telescopic tube upper joint 2-a1, the extension tube head 2-a2, the telescopic tube body 2-a3 and the telescopic tube outer tube 2-a4 are connected by threaded connections, a small liquid hole is opened at the upper end of the telescopic tube body 2-a3, and a locking hole is opened at the lower end of the telescopic tube body 2-a3; the telescopic tube protective cover 2-a5 has a threaded connection at the upper end and is connected to the telescopic tube body 2-a3; the telescopic tube outer tube 2-a4 and the telescopic tube protective cover 2-a5 are connected to the telescopic tube body 2-a3 through threads.

[0101] According to a specific embodiment of the present invention, the movable component 2-b includes a limiting cap 2-b1 and a telescopic tube center tube 2-b2, the telescopic tube center tube 2-b2 has a groove at the lower end, and the limiting cap 2-b1 and the telescopic tube center tube 2-b2 are connected to form a whole by threaded connection.

[0102] According to a specific embodiment of the present invention, the telescopic tube accessory 2-c includes a telescopic tube sealing ring 2-c1 and a telescopic tube anti-loosening screw 2-c2, the telescopic tube sealing ring 2-c1 is sleeved on the outside of the extension tube head 2-a2 and the telescopic tube center tube 2-b2, and the telescopic tube anti-loosening screw 2-c2 connects the telescopic tube upper joint 2-a1 and the extension tube head 2-a2.

[0103] According to a specific embodiment of the present invention, the starting component 2-d includes a starting piston 2-d1, a starting shear pin 2-d2, a starting shear ring 2-d3 and a steel ball 2-d4, the starting piston 2-d1 is arranged in the reserved space between the telescopic tube body 2-a3 and the telescopic tube outer tube 2-a4, the starting shear pin 2-d2 and the starting shear ring 2-d3 are arranged at one end of the starting piston 2-d1, the starting shear pin 2-d2 is embedded in the side wall of the telescopic tube outer tube 2-a4, the starting shear ring 2-d3 is connected to the starting shear pin 2-d2 and is arranged between the telescopic tube body 2-a3 and the telescopic tube outer tube 2-a4, a part of the steel ball 2-d4 is located in the groove at the lower end of the telescopic tube center tube 2-b2, and the other part of the steel ball 2-d4 is located in the locking hole at the lower end of the telescopic tube body 2-a3.

[0104] The starter assembly 2-d is hydraulically controlled. When the telescopic tube body assembly 2-a and the movable assembly 2-b have a tendency to move relative to each other, the steel ball 2-d4 moves radially outward, and the shear ring limits the radial movement space of the steel ball 2-d4. Therefore, the telescopic tube body assembly 2-a and the movable assembly 2-b cannot move, and the assembly into the well is completed. Figure 5 As shown. The starting piston 2-d1 is set in the reserved space between the telescopic tube body 2-a3 and the telescopic tube outer tube 2-a4. The pressure in the pipe column is guided out from the small hole on the telescopic tube body 2-a3 and acts on the starting piston 2-d1. When the set value is reached, the starting piston 2-d1 moves down, pushing the starting shear ring 2-d3 to cut the starting shear pin 2-d2, and the starting shear ring 2-d3 moves down (as shown in FIG. Figure 6 As shown). At this time, the radial limit of the steel ball 2-d4 by the starting shear ring 2-d3 is released, and the steel ball 2-d4 can be squeezed into the inner space of the starting piston 2-d1. The movable component 2-b can move downward under the action of the axial tension to complete the length compensation function. Figure 7The inner diameter of the telescopic tube is denoted as D2.

[0105] The structural features of the downhole tool telescopic tube provided in the present invention, hydraulic opening, and tubing compensation functions, are the basis for lifting the pipe string in the operation process. First, the hydraulically opened telescopic tube can accurately set the opening time of the telescopic tube during the fracturing process to prevent the telescopic tube from being operated in advance and affecting the setting operation; secondly, after the telescopic tube is opened, the operation of unsealing the packer 4 when lifting the pipe string can be unsealed step by step, reducing the axial unsealing load.

[0106] According to a specific embodiment of the present invention, the packer 4 is a hydraulic compression packer, including a packer upper joint 4-1, a packer central pipe 4-2, a packer shear nail 4-3, an upper pressure cap 4-4, a packer sealing ring 4-5, a sealing unit, a liner 4-6, a packer clamp ring 4-10, an upper cone 4-11, a packer outer tube 4-12, a locking ring 4-13, an anchoring mechanism, a lower cone 4-17, a packer lower joint 4-18, a packer anti-drop screw 4-19 and an anti-seating shear nail 4-20. The packer upper joint 4-1, the packer center pipe 4-2 and the packer lower joint 4-18 are connected, the packer sealing ring 4-5 is sleeved on the packer center pipe 4-2, the upper part of the liner 4-6 is connected to the upper pressure cap 4-4, the packer center pipe 4-2 is provided with a plurality of fluid holes, the packer center pipe 4-2 and the liner 4-6 are provided with grooves, the packer clamp ring 4-10 is clamped on the packer center pipe 4-2 and the liner The sealing unit is connected to the outer tube 4-12 of the packer to form a sealed whole; the upper cone 4-11 and the lower cone 4-17 are connected and located in the outer tube 4-12 of the packer; the upper cone 4-11 is a piston structure, and the lower cone 4-17 is connected to the lower end of the liner 4-6; the unsealing shear pin 4-3 is installed in the shear pin hole at the upper end of the upper pressure cap 4-4, and is positioned with the groove of the center tube 4-2 of the packer; the The anti-drop screw is fixed in the screw hole at the lower part of the upper cone 4-11, and the upper part of the anti-drop screw moves in the hole groove on the anchoring mechanism; the anti-sealing shear pin 4-20 is installed in the shear pin hole at the lower end of the outer tube 4-12 of the packer, and is positioned with the groove on the lower cone 4-17; the locking ring 4-13 is installed between the outer tube 4-12 of the packer and the upper cone 4-11, to ensure that the outer tube 4-12 of the packer and the upper cone 4-11 can only move in one direction.

[0107] According to a specific embodiment of the present invention, the center pipe 4-2 of the packer is connected to the lower joint 4-18 of the packer by threaded connection, and the upper part of the liner 4-6 is connected to the upper pressure cap 4-4 by threaded connection; a plurality of fluid holes are opened on the side wall of the center pipe 4-2 of the packer, and a groove is formed on the upper part of the side wall of the center pipe 4-2 of the packer; the lower end of the liner 4-6 is an elastic claw structure, and the middle part of the liner 4-6 is provided with a groove and a fluid hole; the packer retaining ring 4-10 is an open C-type elastic ring.

[0108] According to a specific embodiment of the present invention, the sealing unit includes a rubber cylinder piston 4-9, a rubber cylinder 4-7 and a spacer ring 4-8, the rubber cylinder 4-7 has a plurality of grooves, the spacer ring 4-8 is arranged in the grooves of the rubber cylinder 4-7, and the rubber cylinder piston 4-9 squeezes the rubber cylinder 4-7 and the spacer ring 4-8 to form a sealing unit.

[0109] According to a specific embodiment of the present invention, the lower end of the rubber cylinder piston 4-9 is a threaded structure, which is connected to the outer cylinder 4-12 of the packer through the threaded structure, the lower end of the liner 4-6 has a step, and the lower end of the lower cone 4-17 has a groove inside, and the groove inside the lower end of the lower cone 4-17 is consistent with the step at the lower end of the liner 4-6 to achieve connection and positioning.

[0110] According to a specific embodiment of the present invention, the anchoring mechanism includes a cava 4-16, a spring 4-15 and a cava frame 4-14; the cava 4-16 and the spring 4-15 are installed on the cava frame 4-14, the spring 4-15 is arranged between two of the cava 4-16, the cava frame 4-14 has a hole groove, and the upper part of the anti-drop screw moves in the hole groove on the cava frame 4-14.

[0111] According to a specific embodiment of the present invention, the locking ring 4-13 is an open C-shaped elastic ring with a thread on one side and a one-way tooth on the other side.

[0112] According to a specific embodiment of the present invention, the infinite-stage fracturing sleeve 5 includes an infinite-stage fracturing sleeve body component 5-a, an infinite-stage fracturing sleeve accessory 5-b and an opening tool component 5-c. The opening tool component 5-c is embedded in the side wall of the infinite-stage fracturing sleeve body component 5-a and is connected to the infinite-stage fracturing sleeve accessory 5-b. The opening tool component 5-c controls whether the infinite-stage fracturing sleeve body component 5-a and the infinite-stage fracturing sleeve accessory 5-b are active or not.

[0113] According to a specific embodiment of the present invention, the infinite-stage fracturing sleeve body assembly 5-a includes an infinite-stage fracturing sleeve upper joint 5-a1, an infinite-stage fracturing sleeve body 5-a2, an infinite-stage fracturing sleeve shear pin 5-a3, an infinite-stage fracturing sleeve inner sleeve 5-a4, an infinite-stage fracturing sleeve retaining ring 5-a5 and an infinite-stage fracturing sleeve lower joint 5-a6; the infinite-stage fracturing sleeve upper joint 5-a1 has a slope inside, and is connected to the infinite-stage fracturing sleeve body 5-a2 and the infinite-stage fracturing sleeve lower joint 5-a6 by threads; the infinite-stage fracturing sleeve inner sleeve 5-a4 is pre-placed at a predetermined position on the infinite-stage fracturing sleeve body 5-a2 by the infinite-stage fracturing sleeve shear pin 5-a3; the infinite-stage fracturing sleeve retaining ring 5-a5 is sleeved outside the infinite-stage fracturing sleeve inner sleeve 5-a4 to prevent the infinite-stage fracturing sleeve inner sleeve 5-a4 from moving in the opposite direction.

[0114] According to a specific embodiment of the present invention, the infinite-stage fracturing sleeve clamp ring 5 - a5 is a C-type elastic open ring.

[0115] According to a specific embodiment of the present invention, the opening tool assembly 5-c includes: an upper pumping ball 5-c1, an infinite-stage fracturing sleeve sealing ring 5-c2, an upper ball seat 5-c3, an opening tool body 5-c4, a lower pumping ball 5-c5 and a lower ball seat 5-c6; the upper ball seat 5-c3 and the lower ball seat 5-c6 are provided with sealing grooves, the infinite-stage fracturing sleeve sealing ring 5-c2 is installed in the sealing groove, the upper ball seat 5-c3 and the lower ball seat 5-c6 are connected to the opening tool body 5-c4; the opening tool body 5-c4 is a sleeve with a step, and the right end face of the step of the opening tool body 5-c4 coincides with the lower end of the groove of the inner sleeve 5-a4 of the infinite-stage fracturing sleeve, and the upper joint 5-a1 of the infinite-stage fracturing sleeve has a slope inside.

[0116] The outer circle of the inner sleeve 5-a4 of the infinite-stage fracturing sleeve is provided with a sealing groove and a shearing groove, and the inner circle is designed with a special groove feature. The groove is a groove with a negative angle, that is, compared with the straight step, the angle between the step surface and the radial direction is less than 90 degrees. The inner diameter of the groove is recorded as D5-2, and the groove length is recorded as H. Fig.12 As shown. The diameter of the inner sleeve 5-a4 of the infinite-stage fracturing sleeve is denoted as D5-1.

[0117] The opening tool body 5-c4 is a sleeve with a step, preferably a hollow metal flexible sleeve, the right end face of which is in line with the lower end of the groove of the infinite-stage fracturing sleeve 5-a4. Fig.14The outer diameter of the flexible step is denoted as d5-1, the length of the step is denoted as h, and the outer diameters of the upper ball seat 5-c3 and the lower ball seat 5-c6 are the same, denoted as d5-2. All dimensions satisfy: d5-2 = d5 = D5-1 <d5-1<D5-1。

[0118] When the opening tool assembly 5-c is put into the pipe column, it is pumped to the upper joint and introduced into the tool through the slope there. As mentioned above, the sealing size d5-2 of the front and rear ball seats of the opening tool assembly 5-c is the same as the diameter D5-1 of the inner sleeve 5-a4 of the infinite-stage fracturing sleeve, forming a seal here, and because the upper pumping ball 5-c1 and the lower pumping ball 5-c5 block the downward flow channel of the liquid, the flexible step on the opening tool body 5-c4 is pushed by the axial force generated by the liquid, and the diameter d-51 is reduced to d5 by radial compression, and enters the inner hole of the inner sleeve 5-a4 of the infinite-stage fracturing sleeve.

[0119] When the length h of the flexible step on the opening tool body 5-c4>the inner hole groove length H of the infinite-stage fracturing sleeve inner sleeve 5-a4, the opening tool assembly 5-c continues to pass through the inner hole of the infinite-stage fracturing sleeve 5, such as Fig.15 As shown; on the contrary, the groove on the opening tool body 5-c4 is inserted into the inner groove of the infinite fracturing sleeve 5-a4. Fig.16 shown.

[0120] The structure of the infinite-stage fracturing sleeve 5 of the downhole tool in the present invention is the basis of the layer-changing fracturing. The infinite-stage graded fracturing method adopted in the present invention can achieve full-diameter and equal-diameter pipe strings.

[0121] At this time, under the action of liquid pressure, the opening tool assembly 5-c will move downward with the infinite-stage fracturing sleeve inner sleeve 5-a4, cut off the infinite-stage fracturing sleeve shear pins 5-a3, and move downward to the designed position. At this time, the infinite-stage fracturing sleeve 5 is opened and enters the working state. Fig.17 The infinite-stage fracturing sleeve clamp ring 5-a5 is a C-shaped elastic opening ring, which is installed after the diameter is compressed. At this moment, it will restore the larger diameter to prevent the infinite-stage fracturing sleeve inner sleeve 5-a4 from moving in the opposite direction and closing the sleeve by mistake.

[0122] According to a specific embodiment of the present invention, the slope of the slope inside the upper joint 5-a1 of the infinite-stage fracturing sliding sleeve is less than 25 degrees.

[0123] According to a specific embodiment of the present invention, the upper ball seat 5-c3 and the lower ball seat 5-c6 are connected to the opening tool body 5-c4 by screws; the opening tool body 5-c4 is a hollow metal flexible sleeve with steps.

[0124] According to a specific embodiment of the present invention, the safety release joint 6 includes a safety release upper joint 6-1, a safety release outer tube 6-2, a safety release lower joint 6-3, a safety release sealing ring 6-4 and a safety release shear nail 6-5. The safety release upper joint 6-1 has a slope inside, and the safety release upper joint 6-1 is connected to the safety release outer tube 6-2 as a whole; the safety release upper joint 6-1 is connected to the safety release lower joint 6-3 through the safety release shear nail 6-5.

[0125] According to a specific embodiment of the present invention, the safety release shear nail 6-5 is installed in the threaded hole at the lower end of the safety release outer tube 6-2; the safety release upper joint 6-1 and the safety release outer tube 6-2 are connected as a whole through a threaded connection.

[0126] When the pipe string is stuck, the pipe string load is lifted to a predetermined load, and the safety release shear nail 6-5 is cut off, and the upper safety release joint 6-1 and the safety release outer tube 6-2 of the upper part can be lifted out. Fig.19 As shown; the safety drop lower joint 6-3 is left in the well. The upper end of the lower joint is reserved with a standard tubing thread for later salvage. Fig. 20 The diameter of the safety release joint 6 is denoted as D6.

[0127] In the present invention, the downhole tool safety release joint 6 is the guarantee of release and salvage. The shear-type safety release joint 6 can be used to release the tool in time when the pipe column is buried in sand, and the salvage thread reserved on the safety release joint 6 is convenient for the later use of general salvage tools for salvage. In addition, the pure shear-type safety joint can reduce the number of salvage. Because the shear load F1> the unsealing load F0, if the packer 4 can be unsealed normally and the pipe column can be lifted normally, the safety joint will not be cut off, reducing the number of salvage; if other methods are used, such as hydraulic opening, then regardless of whether the pipe column is stuck, the safety joint will be released, increasing the number of salvage.

[0128] The present invention provides a method for implementing the above-mentioned vertical well infinite-stage oil pipe fracturing string process, comprising the following steps:

[0129] Fracturing string entering the well: after well cleaning, well clearing and wall scraping preparations are completed, the vertical well infinite-stage oil fracturing string is connected, and then the vertical well infinite-stage oil fracturing string is lowered into the predetermined position according to the depth of the target layer, and the wellhead device is set;

[0130] Setting of the packer 4: a setting ball is put in, and it is allowed to settle freely or be pumped to the setting ball seat 7. At this time, a dead space is formed in the pipe string. The wellhead pump truck is pressurized to a preset pressure P0 to complete the setting of the packer 4 downhole. Then the setting ball is removed to achieve communication between the pipe string and the formation.

[0131] fracture:

[0132] First stage of fracturing: inject fracturing fluid, which flows out from the tail end of the pipe string into the formation to complete the first stage of fracturing. The working pressure during fracturing is set to P;

[0133] During the fracturing process, the telescopic tube 2 will reach the working pressure P1 and enter the working state;

[0134] For layer-changing fracturing, the opening tool assembly 5-c is put into the wellhead, the pump is sent to the next level, the pressure is built up to the opening pressure P2 of the infinite-stage fracturing sleeve 5, the infinite-stage fracturing sleeve 5 is opened, and the current layer is fracturing; the changing fracturing is repeated to realize all-stage fracturing;

[0135] Lifting the tubing string load: a ball matching the well-killing valve 1 is dropped from the wellhead, and naturally sinks to the well-killing valve 1. When the pressure of the well-killing valve 1 reaches P3, the well-killing valve 1 is opened, and the well is circulated and killed to the preset qualified standard; the tubing string load is lifted to the preset unsealing load F0, the downhole packer 4 is unsealed, and the whole well tubing string is lifted;

[0136] Release and salvage: In case of sand burial of downhole tools and pipe jam, the pipe load is lifted to the preset release load F1, the safety release joint 6 is cut off, the upper pipe is lifted out, and then sand flushing and salvage are carried out step by step.

[0137] According to a specific embodiment of the present invention, in the process of implementing the vertical well infinite-stage oil pipe fracturing string process, the parameters are set as follows:

[0138] Packer 4 setting and releasing pressure P0 < fracturing pump pressure P;

[0139] Infinite-stage fracturing sleeve 5 opening pressure P1 <P;

[0140] Well killing valve 1 opening pressure P2 < fracturing pump pressure P;

[0141] Packer 4 setting and releasing pressure P0 < telescopic opening pressure P3 < fracturing pump pressure P;

[0142] The fracturing pump pressure P is the maximum design pressure that the tubing string can withstand;

[0143] Unsealing load F0 < releasing load F1.

[0144] Sealing process:

[0145] After the pressure is built up inside the tubing string, the liquid enters the liner 4-6 through the hole on the center tube 4-2 of the packer, and applies the liquid pressure to the rubber cylinder piston 4-9 and the upper cone 4-11 through the liquid hole. The rubber cylinder piston 4-9 squeezes the rubber cylinder 4-7 and the spacer ring 4-8 to form a sealing unit, filling the casing annulus to achieve sealing. At the same time, the liquid pressure pushes the upper cone 4-11 downward, squeezing the cava 4-16, and under the action of the lower cone 4-17, the cava 4-16 compresses the spring 4-15 to move radially outward, bite into the casing, and achieve anchoring. Due to the one-way structure of the locking ring 4-13, the outer tube 4-12 of the packer and the upper cone 4-11 cannot move in the opposite direction, and the sealing state can be maintained even if the sealing pressure is released. Fig. 9 shown.

[0146] Unblocking process:

[0147] Lift the tubing string to the predetermined load, cut the unsealing shear pin 4-3, and the upper joint 4-1, the center pipe 4-2 and the lower joint 4-18 of the packer move upward. The center pipe 4-2 moves to the lower step of the liner 4-6, driving the liner 4-6 upward. Since the upper pressure cap 4-4 is integrated with it, the upper pressure cap 4-4 also moves upward, and the ballast on the rubber cylinder 4-7 is released, and the rubber cylinder 4-7 is restored; at the same time, the packer retaining ring 4-10 on the liner 4-6 drives the rubber cylinder piston 4-9 and the outer cylinder 4-12 of the packer to move upward together. Due to the one-way structure of the locking ring 4-13, the upper cone 4-11 moves upward together, so the ballast on the slip 4-16 is removed, and it contracts radially inward under the seat of the spring 4-15, and the anchoring is released. At this time, the unsealing is completed, as shown in FIG. Fig.10 shown.

[0148] The structure of the packer 4 in the present invention is a guarantee for the packer setting and lifting of the pipe string load. First, the same type of hydraulic packer is used in the whole well, and the same setting method ensures that the packers 4 in the whole well are set successfully at one time, regardless of the number of packers 4. Secondly, the same lifting and unsealing method ensures that the unsealing operation is simple and improves the unsealing success rate.

[0149] Example 1

[0150] According to a specific embodiment of the present invention, the vertical well infinite-stage oil tubing fracturing string process of the present invention is described in detail below.

[0151] The present invention provides a vertical well infinite-stage oil pipe fracturing string process, wherein the vertical well infinite-stage oil pipe fracturing string comprises: a well killing valve 1, a telescopic pipe 2, a hydraulic anchor 3, a packer 4, an infinite-stage fracturing sliding sleeve 5, a safety release joint 6 and a setting ball seat 7;

[0152] The well-killing valve 1 is located at the uppermost end, and a hydraulic anchor 3 and a packer 4 are sequentially arranged between the bottom of the well-killing valve 1 and the top of the first downhole target layer; the hydraulic anchor 3 is anchored on the inner wall of the casing;

[0153] An infinite-stage fracturing sleeve 5, a safety release joint 6 and a packer 4 are sequentially arranged between each downhole target layer and the next downhole target layer; the infinite-stage fracturing sleeve 5 is arranged at each downhole target layer to provide a fluid flow channel during layered fracturing; the infinite-stage fracturing sleeve 5 includes an opening tool component 5-c for controlling the opening of the infinite-stage fracturing sleeve 5, and the safety release joint 6 can achieve shear release when the pipe string is stuck;

[0154] The telescopic pipe 2 is arranged between the packer 4 of each target layer and the infinite-stage fracturing sleeve 5 of the next target layer, and the telescopic pipe 2 is also arranged between the well-killing valve 1 and the hydraulic anchor 3;

[0155] A sealing ball seat 7 is arranged above the target layer closest to the bottom of the artificial well, and the sealing ball seat 7 can provide a pressure holding condition during sealing.

[0156] Example 2

[0157] Different from Example 1, this embodiment adopts infinite-stage partial pressure, and adopts special fracturing sleeve to realize infinite-stage partial pressure of vertical well, and the layer changing operation is simple and efficient. The downhole tool in contact with the opening tool has special requirements on the tool diameter (greater than the outer diameter d5-1 of the opening tool step or equal to the outer diameter d5-2 of the opening tool body) to ensure the smooth passage of the opening tool.

[0158] The infinite-stage fracturing sleeve 5 includes an infinite-stage fracturing sleeve body component 5-a, an infinite-stage fracturing sleeve accessory 5-b and an opening tool component 5-c. The opening tool component 5-c is embedded in the side wall of the infinite-stage fracturing sleeve body component 5-a and is connected to the infinite-stage fracturing sleeve accessory 5-b. The opening tool component 5-c controls the movement of the infinite-stage fracturing sleeve body component 5-a and the infinite-stage fracturing sleeve accessory 5-b.

[0159] Among them, the infinite-stage fracturing sleeve body assembly 5-a includes an infinite-stage fracturing sleeve upper joint 5-a1, an infinite-stage fracturing sleeve body 5-a2, an infinite-stage fracturing sleeve shear pin 5-a3, an infinite-stage fracturing sleeve inner sleeve 5-a4, an infinite-stage fracturing sleeve clamping ring 5-a5 and an infinite-stage fracturing sleeve lower joint 5-a6; the infinite-stage fracturing sleeve upper joint 5-a1 has a slope inside, and is connected to the infinite-stage fracturing sleeve body 5-a2 and the infinite-stage fracturing sleeve lower joint 5-a6 by threads; the infinite-stage fracturing sleeve inner sleeve 5-a4 is pre-placed at a predetermined position on the infinite-stage fracturing sleeve body 5-a2 by the infinite-stage fracturing sleeve shear pin 5-a3; the infinite-stage fracturing sleeve clamping ring 5-a5 is sleeved outside the infinite-stage fracturing sleeve inner sleeve 5-a4 to prevent the infinite-stage fracturing sleeve inner sleeve 5-a4 from moving in the opposite direction.

[0160] Wherein, the infinite-stage fracturing sleeve clamp ring 5-a5 is a C-type elastic open ring.

[0161] Among them, the opening tool assembly 5-c includes: an upper pumping ball 5-c1, an infinite-stage fracturing sleeve sealing ring 5-c2, an upper ball seat 5-c3, an opening tool body 5-c4, a lower pumping ball 5-c5 and a lower ball seat 5-c6; the upper ball seat 5-c3 and the lower ball seat 5-c6 are provided with sealing grooves, the sealing grooves are equipped with the infinite-stage fracturing sleeve sealing ring 5-c2, the upper ball seat 5-c3 and the lower ball seat 5-c6 are connected to the opening tool body 5-c4; the opening tool body 5-c4 is a sleeve with a step, the right end face of the step of the opening tool body 5-c4 coincides with the lower end of the groove of the inner sleeve 5-a4 of the infinite-stage fracturing sleeve, and the upper joint 5-a1 of the infinite-stage fracturing sleeve has a slope inside.

[0162] The outer circle of the inner sleeve 5-a4 of the infinite-stage fracturing sleeve is provided with a sealing groove and a shearing groove, and the inner circle is designed with a special groove feature. The groove is a groove with a negative angle, that is, compared with the straight step, the angle between the step surface and the radial direction is less than 90 degrees. The inner diameter of the groove is recorded as D5-2, and the groove length is recorded as H. Fig.12 As shown. The diameter of the inner sleeve 5-a4 of the infinite-stage fracturing sleeve is denoted as D5-1.

[0163] The opening tool body 5-c4 is a sleeve with a step, preferably a hollow metal flexible sleeve, the right end face of which is in line with the lower end of the groove of the infinite-stage fracturing sleeve 5-a4. Fig.14 The outer diameter of the flexible step is denoted as d5-1, the length of the step is denoted as h, and the outer diameters of the upper ball seat 5-c3 and the lower ball seat 5-c6 are the same, denoted as d5-2. All dimensions satisfy: d5-2 = d5 = D5-1 <d5-1<D5-1。

[0164] When the opening tool assembly 5-c is put into the pipe column, it is pumped to the upper joint and introduced into the tool through the slope there. As mentioned above, the sealing size d5-2 of the front and rear ball seats of the opening tool assembly 5-c is the same as the diameter D5-1 of the inner sleeve 5-a4 of the infinite-stage fracturing sleeve, forming a seal here, and because the upper pumping ball 5-c1 and the lower pumping ball 5-c5 block the downward flow channel of the liquid, the flexible step on the opening tool body 5-c4 is pushed by the axial force generated by the liquid, and the diameter d-51 is reduced to d5 by radial compression, and enters the inner hole of the inner sleeve 5-a4 of the infinite-stage fracturing sleeve.

[0165] When the length h of the flexible step on the opening tool body 5-c4>the inner hole groove length H of the infinite-stage fracturing sleeve inner sleeve 5-a4, the opening tool assembly 5-c continues to pass through the inner hole of the infinite-stage fracturing sleeve 5, such as Fig.15 As shown; on the contrary, the groove on the opening tool body 5-c4 is inserted into the inner groove of the infinite fracturing sleeve 5-a4. Fig.16 shown.

[0166] The structure of the infinite-stage fracturing sleeve 5 of the downhole tool in this embodiment is the basis of the layer-changing fracturing. The infinite-stage graded fracturing method adopted in the present invention can achieve full-diameter and equal-diameter pipe strings.

[0167] At this time, under the action of liquid pressure, the opening tool assembly 5-c will move downward with the infinite-stage fracturing sleeve inner sleeve 5-a4, cut off the infinite-stage fracturing sleeve shear pins 5-a3, and move downward to the designed position. At this time, the infinite-stage fracturing sleeve 5 is opened and enters the working state. Fig.17 The infinite-stage fracturing sleeve clamp ring 5-a5 is a C-shaped elastic opening ring, which is installed after the diameter is compressed. At this moment, it will restore the larger diameter to prevent the infinite-stage fracturing sleeve inner sleeve 5-a4 from moving in the opposite direction and closing the sleeve by mistake.

[0168] Among them, the slope of the slope inside the infinite-stage fracturing sliding sleeve upper joint 5-a1 is less than 25 degrees.

[0169] Among them, the upper ball seat 5-c3 and the lower ball seat 5-c6 are connected to the opening tool body 5-c4 by screws; the opening tool body 5-c4 is a hollow metal flexible sleeve with steps.

[0170] Example 3

[0171] Different from Example 1, this example realizes the setting of the tubing string in one operation. The downhole packers use multiple hydraulic compression packers of the same specifications and models, and all the packers are set in one pressure operation, ensuring that the setting operation of the tubing string is simple, safe and reliable. At the same time, the packers are set before the fracturing operation.

[0172] In this embodiment, the packer 4 is a hydraulic compression packer, including a packer upper joint 4-1, a packer center pipe 4-2, a packer unsealing shear nail 4-3, an upper pressure cap 4-4, a packer sealing ring 4-5, a sealing unit, a liner 4-6, a packer clamp ring 4-10, an upper cone 4-11, a packer outer tube 4-12, a locking ring 4-13, an anchoring mechanism, a lower cone 4-17, a packer lower joint 4-18, a packer anti-drop screw 4-19 and an anti-seating shear nail 4-20; The packer upper joint 4-1, the packer center pipe 4-2 and the packer lower joint 4-18 are connected, the packer sealing ring 4-5 is sleeved on the packer center pipe 4-2, the upper part of the liner 4-6 is connected to the upper pressure cap 4-4, the packer center pipe 4-2 is provided with a plurality of fluid holes, the packer center pipe 4-2 and the liner 4-6 both have grooves, and the packer clamp ring 4-10 is clamped on the packer center pipe 4-2 and the liner 4-6 The sealing unit is connected to the outer tube 4-12 of the packer to form a sealed whole; the upper cone 4-11 and the lower cone 4-17 are connected and located in the outer tube 4-12 of the packer; the upper cone 4-11 is a piston structure, and the lower cone 4-17 is connected to the lower end of the liner 4-6; the unsealing shear pin 4-3 is installed in the shear pin hole at the upper end of the upper pressure cap 4-4, and is positioned with the groove of the center tube 4-2 of the packer; the anti- The anti-drop screw is fixed in the screw hole at the lower part of the upper cone 4-11, and the upper part of the anti-drop screw moves in the hole groove on the anchoring mechanism; the anti-sealing shear pin 4-20 is installed in the shear pin hole at the lower end of the outer tube 4-12 of the packer, and is positioned with the groove on the lower cone 4-17; the locking ring 4-13 is installed between the outer tube 4-12 of the packer and the upper cone 4-11 to ensure that the outer tube 4-12 of the packer and the upper cone 4-11 can only move in one direction.

[0173] Among them, the center pipe 4-2 of the packer and the lower joint 4-18 of the packer are connected by threaded connection, and the upper part of the liner 4-6 is connected to the upper pressure cap 4-4 by threaded connection; the side wall of the center pipe 4-2 of the packer is provided with a plurality of fluid holes, and the upper part of the side wall of the center pipe 4-2 of the packer is provided with a groove; the lower end of the liner 4-6 is an elastic claw structure, and the middle part of the liner 4-6 is provided with a groove and a fluid hole; the packer retaining ring 4-10 is an open C-type elastic ring.

[0174] Among them, the sealing unit includes a rubber cylinder piston 4-9, a rubber cylinder 4-7 and a spacer ring 4-8, the rubber cylinder 4-7 has a plurality of grooves, the spacer ring 4-8 is arranged in the grooves of the rubber cylinder 4-7, and the rubber cylinder piston 4-9 squeezes the rubber cylinder 4-7 and the spacer ring 4-8 to form a sealing unit.

[0175] Among them, the lower end of the rubber cylinder piston 4-9 is a threaded structure, which is connected to the outer tube 4-12 of the packer through the threaded structure. The lower end of the liner 4-6 has a step, and the lower end of the lower cone 4-17 has a groove inside. The groove inside the lower end of the lower cone 4-17 is consistent with the step at the lower end of the liner 4-6 to achieve connection and positioning.

[0176] Among them, the anchoring mechanism includes a cava 4-16, a spring 4-15 and a cava frame 4-14; the cava 4-16 and the spring 4-15 are installed on the cava frame 4-14, the spring 4-15 is arranged between two of the cava 4-16, the cava frame 4-14 has a hole groove, and the upper part of the anti-drop screw moves in the hole groove on the cava frame 4-14.

[0177] Wherein, the locking ring 4-13 is an open C-shaped elastic ring with a thread on one side and a one-way tooth on the other side.

[0178] Example 4

[0179] According to a specific embodiment of the present invention, the method for implementing the above-mentioned vertical well infinite-stage oil tubing fracturing string process is described in detail below.

[0180] The present invention provides a method for implementing the above-mentioned vertical well infinite-stage oil pipe fracturing string process, comprising the following steps:

[0181] Fracturing string entering the well: after well cleaning, well clearing and wall scraping preparations are completed, the vertical well infinite-stage oil fracturing string is connected, and then the vertical well infinite-stage oil fracturing string is lowered into the predetermined position according to the depth of the target layer, and the wellhead device is set;

[0182] Setting of the packer 4: a setting ball is put in, and it is allowed to settle freely or be pumped to the setting ball seat 7. At this time, a dead space is formed in the pipe string. The wellhead pump truck is pressurized to a preset pressure P0 to complete the setting of the packer 4 downhole. Then the setting ball is removed to achieve communication between the pipe string and the formation.

[0183] fracture:

[0184] First stage of fracturing: inject fracturing fluid, which flows out from the tail end of the pipe string into the formation to complete the first stage of fracturing. The working pressure during fracturing is set to P;

[0185] During the fracturing process, the telescopic tube 2 will reach the working pressure P1 and enter the working state;

[0186] For layer-changing fracturing, the opening tool assembly 5-c is put into the wellhead, the pump is sent to the next level, the pressure is built up to the opening pressure P2 of the infinite-stage fracturing sleeve 5, the infinite-stage fracturing sleeve 5 is opened, and the current layer is fracturing; the changing fracturing is repeated to realize all-stage fracturing;

[0187] Lifting the tubing string load: a ball matching the well-killing valve 1 is dropped from the wellhead, and naturally sinks to the well-killing valve 1. When the pressure of the well-killing valve 1 reaches P3, the well-killing valve 1 is opened, and the well is circulated and killed to the preset qualified standard; the tubing string load is lifted to the preset unsealing load F0, the downhole packer 4 is unsealed, and the whole well tubing string is lifted;

[0188] Release and salvage: In case of sand burial of downhole tools and pipe jam, the pipe load is lifted to the preset release load F1, the safety release joint 6 is cut off, the upper pipe is lifted out, and then sand flushing and salvage are carried out step by step.

[0189] This embodiment realizes pipe string compensation. The telescopic pipe at the upper end of the pipe string provides telescopic compensation during fracturing to ensure the safety of the fracturing pipe string; the telescopic pipe between the packers is activated during the fracturing process, and can provide a certain stroke at the lower part of the packer when the pipe string is lifted, reducing the unsealing load and achieving step-by-step unsealing.

[0190] At the same time, this embodiment adopts a shear-type safety release joint, which is opened by axial load in the event of accidents such as tool sand burial. It provides the possibility of step-by-step salvage. At the same time, the axial load is used instead of the hydraulic opening method, which is consistent with the packer unsealing method. It is opened only when needed, minimizing the number of unnecessary salvage.

[0191] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention are included in the protection scope of the present invention.

Claims

1. A vertical well infinite-stage oil pipe fracturing string process, characterized in that: The vertical well infinite-stage oil pipe fracturing string comprises: a well killing valve, a telescopic pipe, a hydraulic anchor, a packer, an infinite-stage fracturing sliding sleeve, a safety release joint and a setting ball seat; The well-killing valve is located at the uppermost end, and a hydraulic anchor and a packer are sequentially arranged between the lower part of the well-killing valve and the upper part of the first downhole target layer; the hydraulic anchor is anchored on the inner wall of the casing; An infinite-stage fracturing sleeve, a safety release joint and a packer are sequentially arranged between each downhole target layer and the next downhole target layer; the infinite-stage fracturing sleeve is arranged at each downhole target layer to provide a fluid flow channel during layered fracturing; the infinite-stage fracturing sleeve includes an opening tool assembly for controlling the opening of the infinite-stage fracturing sleeve, and the safety release joint can realize shear release when the pipe string is stuck; The telescopic pipe is arranged between the packer of each target layer and the infinite-stage fracturing sleeve of the next target layer, and the telescopic pipe is also arranged between the well-killing valve and the hydraulic anchor; A sealing ball seat is arranged above the target layer closest to the bottom of the artificial well, and the sealing ball seat can provide a pressure holding condition during sealing.

2. The vertical well infinite-stage oil pipe fracturing string process according to claim 1 is characterized in that: The packer is a hydraulic compression packer.

3. The vertical well infinite-stage oil pipe fracturing string process according to claim 1 is characterized in that: The well-killing valve comprises a well-killing valve body, an inner sleeve assembly and an opening ball, wherein the inner sleeve assembly is located inside the well-killing valve body, the opening ball is located inside the well-killing valve body, the inner sleeve assembly can slide along the inner wall of the well-killing valve body, and the opening ball can slide down along the inside of the inner sleeve assembly.

4. The vertical well infinite-stage oil pipe fracturing string process according to claim 3 is characterized in that: The well-killing valve body comprises an upper joint of the well-killing valve body, a well-killing valve body anti-loosening screw and a lower joint of the well-killing valve body; a liquid outlet is arranged in the middle part above the upper joint of the well-killing valve body, the upper joint of the well-killing valve body and the lower joint of the well-killing valve body are connected by threads and are fastened by the well-killing valve body anti-loosening screw.

5. The vertical well infinite-stage oil pipe fracturing string process according to claim 4 is characterized in that: The inner sleeve assembly comprises an inner sleeve of a well-killing valve, a sealing ring of the well-killing valve and an opening shear pin. The upper end of the inner sleeve of the well-killing valve has a step with a slope and is fixed in a predetermined closing position by the opening shear pin. The sealing ring of the well-killing valve is sleeved on the outside of the inner sleeve of the well-killing valve.

6. The vertical well infinite-stage oil pipe fracturing string process according to claim 5, characterized in that: The slope of the step at the upper end of the sliding sleeve in the well-killing valve is less than 25 degrees.

7. The vertical well infinite-stage oil pipe fracturing string process according to claim 1, characterized in that: The telescopic tube includes a telescopic tube body component, a movable component, a telescopic tube accessory and a starting component. The movable component is arranged inside the telescopic tube body component. The movable component and the telescopic tube body component have a reserved stroke for relative movement to realize a column length compensation function. The telescopic tube accessory is arranged at one end inside the telescopic tube body component and is used to connect the telescopic tube body component and set a seal. The starting component is embedded in the side wall of the other end of the telescopic tube body component and is connected to the movable component. The starting component controls whether the telescopic tube body component and the movable component are movable or not.

8. The vertical well infinite-stage oil pipe fracturing string process according to claim 7, characterized in that: The telescopic tube body assembly comprises a telescopic tube upper joint, an extension tube, a telescopic tube body, a telescopic tube outer tube and a telescopic tube protective cover; wherein the telescopic tube upper joint, the extension tube, the telescopic tube body and the telescopic tube outer tube are connected by threaded connection, a liquid-passing hole is provided at the upper end of the telescopic tube body, and a locking hole is provided at the lower end of the telescopic tube body; a thread is provided at the upper end of the telescopic tube protective cover and is connected to the telescopic tube body; the telescopic tube outer tube and the telescopic tube protective cover are connected to the telescopic tube body by threaded connection.

9. The vertical well infinite-stage oil pipe fracturing string process according to claim 8, characterized in that: The movable component comprises a limiting cap and a telescopic tube center tube, a groove is arranged at the lower end of the telescopic tube center tube, and the limiting cap and the telescopic tube center tube are connected as a whole through threads.

10. The vertical well infinite-stage oil pipe fracturing string process according to claim 9, characterized in that: The telescopic tube accessories include a telescopic tube sealing ring and a telescopic tube anti-loosening screw. The telescopic tube sealing ring is sleeved on the outside of the extension tube and the telescopic tube center tube. The telescopic tube anti-loosening screw connects the telescopic tube upper joint and the extension tube.

11. The vertical well infinite-stage oil pipe fracturing string process according to claim 10, characterized in that: The starting assembly includes a starting piston, a starting shear pin, a starting shear ring and a steel ball. The starting piston is arranged in a reserved space between the telescopic tube body and the telescopic tube outer tube. The starting shear pin and the starting shear ring are arranged at one end of the starting piston. The starting shear pin is embedded in the side wall of the telescopic tube outer tube. The starting shear ring is connected to the starting shear pin and is arranged between the telescopic tube body and the telescopic tube outer tube. A part of the steel ball is located in the groove at the lower end of the telescopic tube center tube, and the other part of the steel ball is located in the locking hole at the lower end of the telescopic tube body.

12. The vertical well infinite-stage oil pipe fracturing string process according to claim 1, characterized in that: The packer is a hydraulic compression packer, including a packer upper joint, a packer center tube, a sealing shear pin, an upper pressure cap, a packer sealing ring, a sealing unit, a liner, a packer clamp, an upper cone, a packer outer tube, a locking ring, an anchoring mechanism, a lower cone, a packer lower joint, a packer anti-drop screw and an anti-seating shear pin; the packer upper joint and the packer center tube are connected to the packer lower joint, the packer sealing ring is sleeved on the packer center tube, the upper part of the liner is connected to the upper pressure cap, the packer center tube is provided with a plurality of liquid holes, the packer center tube and the liner both have grooves, the packer clamp is clamped in the grooves of the packer center tube and the liner; the sealing unit is connected to the The outer tube of the packer is connected to form a sealed whole; the upper cone and the lower cone are connected and are located in the outer tube of the packer; the upper cone is a piston structure, and the lower cone is connected to the lower end of the liner; the unsealing shear pin is installed in the shear pin hole at the upper end of the upper pressure cap, and is positioned with the groove of the center tube of the packer; the anti-drop screw is fixed in the screw hole at the lower part of the upper cone, and the upper part of the anti-drop screw moves in the hole groove on the anchoring mechanism; the anti-sealing shear pin is installed in the shear pin hole at the lower end of the outer tube of the packer, and is positioned with the groove on the lower cone; the locking ring is installed between the outer tube of the packer and the upper cone to ensure that the outer tube of the packer and the upper cone can only move in one direction.

13. The vertical well infinite-stage oil pipe fracturing string process according to claim 12, characterized in that: The center tube of the packer is connected to the lower joint of the packer by threaded connection, and the upper part of the liner is connected to the upper pressure cap by threaded connection; a plurality of fluid holes are opened on the side wall of the center tube of the packer, and a groove is provided on the upper part of the side wall of the center tube of the packer; the lower end of the liner is an elastic claw structure, and the middle part of the liner is provided with a groove and a fluid hole; the packer retaining ring is an open C-shaped elastic ring.

14. The vertical well infinite-stage oil pipe fracturing string process according to claim 12, characterized in that: The sealing unit comprises a rubber cylinder piston, a rubber cylinder and a spacer ring. The rubber cylinder has a plurality of grooves. The spacer ring is arranged in the grooves of the rubber cylinder. The rubber cylinder piston squeezes the rubber cylinder and the spacer ring to form a sealing unit.

15. The vertical well infinite-stage oil pipe fracturing string process according to claim 12, characterized in that: The lower end of the rubber cylinder piston is a threaded structure, which is connected to the outer tube of the packer through the threaded structure. The lower end of the liner has a step, and the lower end of the lower cone has a groove inside. The groove inside the lower end of the lower cone matches the step at the lower end of the liner to achieve connection and positioning.

16. The vertical well infinite-stage oil pipe fracturing string process according to claim 12, characterized in that: The anchoring mechanism comprises a slip, a spring and a slip frame; the slip and the spring are mounted on the slip frame, the spring is arranged between two slips, the slip frame has a hole groove, and the upper part of the anti-drop screw moves in the hole groove on the slip frame.

17. The vertical well infinite-stage oil pipe fracturing string process according to claim 12, characterized in that: The locking ring is an open C-shaped elastic ring with a thread on one side and a one-way tooth on the other side.

18. The vertical well infinite-stage oil pipe fracturing string process according to claim 1, characterized in that: The infinite-stage fracturing sleeve comprises an infinite-stage fracturing sleeve body component, an infinite-stage fracturing sleeve accessory and an opening tool component. The opening tool component is embedded in the side wall of the infinite-stage fracturing sleeve body component and connected to the infinite-stage fracturing sleeve accessory. The opening tool component controls whether the infinite-stage fracturing sleeve body component and the infinite-stage fracturing sleeve accessory are movable or not.

19. The vertical well infinite-stage oil pipe fracturing string process according to claim 18, characterized in that: The infinite-stage fracturing sleeve body assembly comprises an infinite-stage fracturing sleeve upper joint, an infinite-stage fracturing sleeve body, an infinite-stage fracturing sleeve shear pin, an infinite-stage fracturing sleeve inner sleeve, an infinite-stage fracturing sleeve clamping ring and an infinite-stage fracturing sleeve lower joint; The upper joint of the infinite-stage fracturing sleeve has a slope inside, and is connected to the infinite-stage fracturing sleeve body and the infinite-stage fracturing sleeve lower joint through threads; the inner sleeve of the infinite-stage fracturing sleeve is pre-placed at a predetermined position on the infinite-stage fracturing sleeve body through the infinite-stage fracturing sleeve shear pins; the infinite-stage fracturing sleeve retaining ring is arranged outside the inner sleeve of the infinite-stage fracturing sleeve to prevent the inner sleeve of the infinite-stage fracturing sleeve from moving in the opposite direction.

20. The vertical well infinite-stage oil pipe fracturing string process according to claim 19, characterized in that: The infinite-stage fracturing sleeve clamp ring is a C-shaped elastic open ring.

21. The vertical well infinite-stage oil pipe fracturing string process according to claim 19, characterized in that: The opening tool assembly includes: an upper pumping ball, an infinite-stage fracturing sleeve sealing ring, an upper ball seat, an opening tool body, a lower pumping ball and a lower ball seat; the upper ball seat and the lower ball seat are provided with sealing grooves, the infinite-stage fracturing sleeve sealing ring is installed in the sealing groove, and the upper ball seat and the lower ball seat are connected to the opening tool body; the opening tool body is a sleeve with a step, the right end face of the step of the opening tool body is consistent with the lower end of the groove of the inner sleeve of the infinite-stage fracturing sleeve, and the upper joint of the infinite-stage fracturing sleeve has a slope inside.

22. The vertical well infinite-stage oil pipe fracturing string process according to claim 21, characterized in that: The slope of the slope inside the upper joint of the infinite-stage fracturing sliding sleeve is less than 25 degrees.

23. The vertical well infinite-stage oil pipe fracturing string process according to claim 21, characterized in that: The upper ball seat and the lower ball seat are connected to the opening tool body through screws; the opening tool body is a hollow metal flexible sleeve with steps.

24. The vertical well infinite-stage oil pipe fracturing string process according to claim 1, characterized in that: The safety release joint comprises a safety release upper joint, a safety release outer cylinder, a safety release lower joint, a safety release sealing ring and a safety release shear nail. The safety release upper joint has a slope inside. The safety release upper joint is connected to the safety release outer cylinder as a whole; the safety release upper joint is connected to the safety release lower joint through the safety release shear nail.

25. The vertical well infinite-stage oil pipe fracturing string process according to claim 24, characterized in that: The safety release shear nail is installed in the threaded hole at the lower end of the safety release outer tube; the safety release upper joint and the safety release outer tube are connected as a whole through a thread.

26. A method for implementing the vertical well infinite-stage oil pipe fracturing string process according to any one of claims 1 to 25, characterized in that: The steps include: Fracturing string entering the well: after well cleaning, well clearing and wall scraping preparations are completed, the vertical well infinite-stage oil fracturing string is connected, and then the vertical well infinite-stage oil fracturing string is lowered into the predetermined position according to the depth of the target layer, and the wellhead device is set; Packer setting: a setting ball is put in, and it is allowed to settle freely or be pumped to the setting ball seat. At this time, a dead cavity is formed in the tubing string. The wellhead pump truck pumps the pressure to the preset pressure P0 to complete the setting of the packer downhole. Then the setting ball is knocked out to achieve communication between the tubing string and the formation. fracture: First stage of fracturing: inject fracturing fluid, which flows out from the tail end of the pipe string into the formation to complete the first stage of fracturing. The working pressure during fracturing is set to P; During the fracturing process, the telescopic tube will reach the working pressure P1 and enter the working state; Layer-changing fracturing: the opening tool assembly is put into the wellhead, the pump is sent to the next level, the pressure is built up to the opening pressure P2 of the infinite-stage fracturing sleeve, the infinite-stage fracturing sleeve is opened, and the current layer is fracturing; the changing fracturing is repeated to achieve fracturing of all levels; Lifting the tubing string load: a ball matching the well-killing valve is dropped from the wellhead, and naturally sinks to the well-killing valve. When the pressure of the well-killing valve reaches P3, the well-killing valve is opened, and the well is cycled to the preset qualified standard; the tubing string load is lifted to the preset unsealing load F0, the downhole packer is unsealed, and the whole well tubing string is lifted; Release and salvage: In case of sand burial of downhole tools and pipe jam, the pipe load is lifted to the preset release load F1, the safety release joint is cut off, the upper pipe is lifted out, and then sand flushing and salvage are carried out step by step.

27. The method for implementing the vertical well infinite-stage oil pipe fracturing string process according to claim 26, characterized in that: In the process of implementing the vertical well infinite-stage tubing fracturing string process, the parameters are set as follows: Packer setting and releasing pressure P0 < fracturing pump pressure P; Infinite-stage fracturing sleeve opening pressure P1 <P; Well killing valve opening pressure P2 < fracturing pump pressure P; Packer setting and releasing pressure P0 < telescopic opening pressure P3 < fracturing pump pressure P; The fracturing pump pressure P is the maximum design pressure that the tubing string can withstand; Unsealing load F0 < releasing load F1.

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