CN117404047A - Full-drift-diameter fracturing sliding sleeve, tubular column and operation method of full-drift-diameter fracturing sliding sleeve - Google Patents

Abstract

The invention provides a full-drift-diameter fracturing sliding sleeve, which comprises the following components: an outer cylinder provided with a diversion hole; an upper joint and a lower joint respectively connected with two ends of the outer cylinder; an inner cylinder concentrically arranged in the outer cylinder, the inner cylinder being fixed with the outer cylinder by a first shear pin; the lower sleeve is arranged at the lower end of the inner cylinder and is fixed with the inner cylinder through a second shear pin; the second shearing pin has a shearing critical value larger than that of the first shearing pin, the opening tool can be matched with the inner barrel through the falling, the inner barrel is driven to shear the first shearing pin through the action of pressure difference to descend until the lower sleeve is propped against the upper end face of the lower joint to open the flow guide hole, the inner barrel can shear the second shearing pin under the action of pressure to continue descending, and the opening tool is contracted to fracture the sliding sleeve through the full-path. The invention also provides an operation method of the tubular column and the full-drift-diameter fracturing sliding sleeve.

Description

Full-drift-diameter fracturing sliding sleeve, tubular column and operation method of full-drift-diameter fracturing sliding sleeve

Technical Field

The invention belongs to the field of oil and gas well completion and fracturing operation, and particularly relates to a full-drift-diameter fracturing sliding sleeve, a tubular column and an operation method thereof.

Background

Multistage staged fracturing, especially staged fracturing of horizontal wells, is a major technique for improving oil and gas recovery efficiency in the development process of unconventional oil and gas reservoirs such as shale gas, dense gas and the like. In the multistage fracturing process, the number of tool fracturing channel clusters is increased, so that the complexity of the seam network of the reservoir reconstruction stratum can be increased, and effective communication is formed between the seam networks.

In the prior art, the multistage multi-cluster fracturing tool mainly adopts the combined operation technology of bridge plugs and perforations, and has the defects of multiple operation procedures, long construction time, high operation cost, discontinuous construction and the like. The conventional multistage sliding sleeve packer staged fracturing technology divides the production zone into a plurality of zones through the packer according to the production zone condition, and then the sliding sleeve is opened by throwing balls or special opening tools, so that the successive fracturing operation can be realized, the construction is continuous, and the operation procedure is simplified.

The Chinese patent application ZL201210587000.7 discloses a ball-throwing-opening multi-cluster sliding sleeve, which can realize that a plurality of multi-cluster sliding sleeves can be opened by throwing one ball, but the size of the ball is larger and larger from bottom to top due to the adoption of a conventional ball throwing mode, the sectional level is limited due to the fact that the inner diameter of a shaft is fixed, the unlimited level cannot be realized, and the full-path cannot be realized due to the fact that the inner paths of sliding sleeves of different levels are gradually reduced, so that the pumping efficiency of ground pumping equipment is limited to be exerted to the maximum extent.

The Chinese patent application ZL201610037797.1 discloses a novel sliding sleeve, a sliding sleeve opening tool and a fracturing string, wherein the sliding sleeve has a full-drift diameter stepless function, but only one sliding sleeve can be opened by one opening tool, a plurality of sliding sleeves cannot be opened by one opening tool, and the requirement of site construction on a multi-section multi-cluster technology cannot be met.

Disclosure of Invention

Aiming at the technical problems, the invention aims to provide the full-drift-diameter fracturing sliding sleeve which is matched with a conventional stepless sliding sleeve for use, a plurality of full-drift-diameter fracturing sliding sleeves and the conventional stepless sliding sleeve are arranged on a tubular column, and the plurality of stepless multi-cluster fracturing sliding sleeves can be opened by one opening tool so as to meet the requirements of the transformation of an unconventional oil and gas reservoir.

To this end, according to a first aspect of the present invention, there is provided a full-bore fracturing sleeve comprising: the outer cylinder is provided with a diversion hole penetrating through the side wall of the outer cylinder; an upper connector and a lower connector respectively connected to two ends of the outer cylinder; an inner cylinder concentrically arranged in the outer cylinder, the inner cylinder being fixed to the outer cylinder by a first shear pin; the lower sleeve is arranged at the lower end of the inner cylinder and is fixed with the inner cylinder through a second shear pin; the second shearing pin has a shearing critical value larger than that of the first shearing pin, the opening tool can be matched with the inner cylinder through the falling, the inner cylinder is driven to shear the first shearing pin through the action of pressure difference to descend until the lower sleeve is propped against the upper end face of the lower joint to open the flow guide hole, the inner cylinder can shear the second shearing pin under the action of pressurization to continue descending, and the opening tool is contracted to pass through the full-diameter fracturing sliding sleeve.

In one embodiment, the opening tool is configured to include a ball seat portion and a resilient claw fixedly connected to an upper end of the ball seat portion, an outer surface of the resilient claw is provided with a first protrusion, an inner wall of the inner barrel is provided with a first annular groove, and the first protrusion is capable of being matched with the first annular groove and transmitting axial pressure.

In one embodiment, the inner wall of the inner cylinder is further provided with a plurality of second annular grooves which are uniformly distributed at intervals along the axial direction, the side wall surface of the second annular groove is configured into a first inclined surface, the outer surface of the elastic claw is provided with a plurality of second protruding parts which can be matched with the second annular groove, and the inner cylinder can apply pressure to the upper end surface of the second protruding parts through the side wall surface of the second annular groove, so that the elastic claw radially contracts.

In one embodiment, the inner wall of the ball seat portion is configured with a conical surface for fitting with a pressure-holding ball.

In one embodiment, the outer wall of the lower sleeve is provided with an upward facing step, and the upper end portion of the lower sleeve is inserted into the inner cylinder to be fixed with the inner cylinder by a second shear pin, and a space is formed between the lower end surface of the inner cylinder and the end surface of the step.

In one embodiment, the upper end surface of the lower sleeve is configured as a third chamfer.

In one embodiment, two first sealing elements are arranged between the inner cylinder and the outer cylinder in a spaced mode, and when the diversion holes are closed, the diversion holes and the first shearing pins are located between the axial directions of the two first sealing elements.

In one embodiment, the upper joint and the lower joint are both configured as step-shaped connecting buckles, and second sealing elements are respectively arranged between the connecting surfaces of the upper joint, the lower joint and the outer barrel.

According to a second aspect of the invention, there is provided a tubular string, comprising a plurality of full-bore fracturing slips as described above, a plurality of said full-bore fracturing slips being connected in series, said opening tool being capable of sequentially opening and passing through respective ones of said full-bore fracturing slips.

According to a third aspect of the invention, there is provided a method of operating a full-bore fracturing slide sleeve, characterized by comprising the steps of:

step one: connecting a plurality of full-path fracturing sliding sleeves in series into a tubular column, and running the tubular column into a preset stratum;

step two: throwing the opening tool from a wellhead, and pumping the opening tool to the corresponding full-diameter fracturing sliding sleeve;

step three: the opening tool is matched with the inner cylinder, and drives the lower sleeve to descend after shearing the first shearing pin under the action of pressure difference, so that the diversion hole is opened;

step four: continuously pressurizing until the inner barrel shears the second shear pin, and enabling the inner barrel to shrink under the action of pressure difference, so that the opening tool passes through the corresponding full-diameter fracturing sliding sleeve and descends to the next stage of full-diameter fracturing sliding sleeve;

step five: and the opening tool repeats the third step and the fourth step until all the full-diameter fracturing sliding sleeves are opened.

Compared with the prior art, the application has the advantages that:

the full-drift-diameter fracturing sliding sleeve disclosed by the invention is matched with a conventional stepless sliding sleeve for use, can be used as a stepless multi-cluster fracturing sliding sleeve, and can be opened by one opening tool to meet the requirements of the reconstruction of an unconventional oil and gas reservoir. The operation method of the full-drift-diameter fracturing sliding sleeve is simple to operate, can greatly improve the opening efficiency of the sliding sleeve, can effectively ensure the success rate of opening the sliding sleeve, and is very beneficial to improving the operation efficiency of reservoir reconstruction of the oil and gas reservoirs.

Drawings

The present invention will be described below with reference to the accompanying drawings.

Fig. 1 schematically shows the structure of a full-path fracturing sleeve according to the present invention.

Fig. 2 schematically shows the structure of an opener according to the invention.

Fig. 3 schematically illustrates the connection between the inner barrel and the lower sleeve in the full-path fracturing sleeve of fig. 1.

Fig. 4 to 6 show the opening process of the full-path fracturing sleeve according to the present invention.

In this application, all of the figures are schematic drawings which are intended to illustrate the principles of the invention and are not to scale.

Detailed Description

The invention is described below with reference to the accompanying drawings.

In the present application, it should be noted that an end of the full-path fracturing sliding sleeve lowered into the wellbore near the wellhead is defined as an upper end or a similar term, and an end far from the wellhead is defined as a lower end or a similar term. The directional terms or qualifiers "upper", "lower", and the like used in this application are used with reference to fig. 1. They are not intended to limit the absolute position of the parts involved, but may vary according to the specific circumstances.

Fig. 1 schematically illustrates the structure of a full-path fracturing sleeve 100 according to the present invention. As shown in fig. 1, the full-path fracturing sliding sleeve 100 includes an outer cylinder 1, an inner cylinder 4 concentrically arranged inside the outer cylinder 1, a lower sleeve 6, and an upper joint 2 and a lower joint 3 respectively connected to the upper and lower ends of the outer cylinder 1. The outer cylinder 1 is provided with a deflector hole 11 penetrating its side wall. In the initial state, the inner cylinder 4 is fixed with the outer cylinder 1 through the first shear pin 5, and the lower sleeve 6 is connected to the lower end of the inner cylinder 4 and fixed with the inner cylinder 4 through the second shear pin 7. The shear threshold of the second shear pin 7 is greater than the shear threshold of the first shear pin 5. During actual operation, the opening tool 200 can be matched with the inner cylinder 4 when reaching the position of the full-diameter fracturing sliding sleeve 100 through the opening tool 200, and the inner cylinder 4 is driven to shear the first shearing pin 5 and then move downwards through the pressure difference effect until the lower sleeve 6 is abutted against the upper end face of the lower joint 3, so that the diversion hole 11 is opened, the pressurization is continued, the inner cylinder 4 can continuously move downwards after shearing the second shearing pin 7 when reaching the critical shearing value of the second shearing pin 7, and the opening tool 200 can be contracted inwards in the radial direction, so that the opening tool 200 passes through the full-diameter fracturing sliding sleeve 100.

In one embodiment, the deflector holes 11 are provided in plurality, and the plurality of deflector holes 11 are each distributed at a distance from each other in the circumferential direction. The size and number of the deflector holes 11 can be adjusted according to the number of clusters in actual situations. Preferably, the deflector hole 11 is provided at a position near the upper end of the outer tub 1.

As shown in fig. 1, the upper joint 2 and the lower joint 3 are each constructed as a stepped joint buckle, and the stepped joint buckle is provided with external threads. The step-shaped connecting buckle corresponding to the upper joint 2 is inserted into the outer cylinder 1 and extends downwards, and is fixedly connected with the upper end of the outer cylinder 1 in a threaded connection mode. Similarly, the step-shaped connecting buckle corresponding to the lower joint 3 is inserted into the outer cylinder 1 and extends upwards, and is fixedly connected with the lower end of the outer cylinder 1 in a threaded connection mode. Thereby, the upper end surface of the lower joint 3 is formed inside the outer tube 1, and is formed as an inner stepped surface with an end surface facing upward.

In order to ensure tightness between the upper joint 2, the lower joint 3 and the outer cylinder 1, second sealing members 9 are respectively arranged between the connecting surfaces of the upper joint 2, the lower joint 3 and the outer cylinder 1. Preferably, a radially inwardly extending sealing groove is provided on the outer surface of the upper joint 2, the lower joint 3, in which a second seal 9 is mounted.

According to the invention, two first seals 8 are arranged between the inner cylinder 4 and the outer cylinder 1, which seals are spaced apart, the pilot hole 11 and the first shear pin 5 being located axially between the two first seals 8 when the pilot hole 11 is in the closed state. Thus, the tightness of the full-diameter fracturing sliding sleeve 100 can be effectively ensured, and the internal pressure of the full-diameter fracturing sliding sleeve 100 is effectively ensured. In one embodiment, seal mounting grooves are provided on the outer wall of the inner tube 4, which are distributed at intervals from each other in the circumferential direction, and two second seals 8 are respectively mounted in the corresponding seal mounting grooves.

According to the present invention, as shown in fig. 2, the opener 200 is configured to include a ball seat portion 210 and a resilient claw 220 fixedly coupled to an upper end of the ball seat portion 210. The inner wall of the ball seat portion 210 is configured with a conical surface 211 for fitting with the pressure holding ball 201. To facilitate running of the opener 200 into the wellbore, the lower end surface of the ball seat portion 210 is configured as a tapered surface to facilitate guiding the running of the opener 200.

In the present embodiment, the plurality of elastic claws 220 are provided, and the plurality of elastic claws 220 are evenly spaced apart in the circumferential direction.

According to the present invention, as shown in fig. 1 and 2, a first protrusion 221 is provided at an outer surface of the elastic claw 220. Meanwhile, a first annular groove 41 is provided in the inner wall of the inner cylinder. The first boss 221 is capable of engaging with the first annular groove 41 and transmitting axial pressure. The first boss 221 is rectangular in cross section, and the first annular groove 41 is also rectangular in cross section. Preferably, the first boss 221 is provided at a position of the elastic claw 220 near the upper end. And, the axial width of the first annular groove 41 is larger than the axial width of the first boss 221. During operation, when the opener 100 reaches the corresponding full-path fracturing slide sleeve 100, the first protruding portion 221 can be fitted into the first annular groove 41 to form a fit, so that the lower end face of the first protruding portion 221 abuts against the lower side wall face of the first annular groove 41, and therefore the opener 200 can transmit pressure to the lower side wall face of the first annular groove 41 through the lower end face of the first protruding portion 221 and further to the inner cylinder 4.

As shown in fig. 2 and 3, the inner wall of the inner cylinder 4 is further provided with a plurality of second annular grooves 42 uniformly spaced apart in the axial direction, and the side wall surfaces of the second annular grooves 42 are configured as first inclined surfaces 421. Meanwhile, the outer surface of the elastic claw 220 is further provided with a plurality of second protrusions 222 capable of being engaged with the second annular groove 42. The upper and lower end surfaces of the second boss 222 are also configured as a second slope 223 that can be fitted with the first slope 421. The axial width of the second annular groove 42 is greater than the axial width of the second boss 222. The inner cylinder 4 can apply pressure to the upper end surface (the third inclined surface 223) of the second boss 222 through the side wall surface (the first inclined surface 421) of the second annular groove 42, so that the elastic claw 220 is contracted radially inwards by utilizing the cooperation between the first inclined surface 421 and the second inclined surface 223, the cooperation between the elastic claw 220 and the inner cylinder 4 is released, and the opening tool 200 can fracture the sliding sleeve 100 through the full-path.

Preferably, the second boss 222 is at the lower end of the first boss 221.

According to the invention, an upwardly facing step 61 is provided in the outer wall of the lower sleeve 6 near the lower end. The upper end portion of the lower sleeve 6 is inserted into the inner cylinder 4 to be fixed with the inner cylinder 4 by the second shear pin 7. And, a space is formed between the lower end face of the inner tube 4 and the end face of the step 61 so that the inner tube 4 can move relatively with respect to the lower sleeve 6.

In one embodiment, the upper end surface of the lower sleeve 6 is configured as a third chamfer 62. In the embodiment shown in fig. 3, the third inclined surface 62 at the upper end of the lower sleeve 6 forms a second annular groove 42 together with the first inclined surface 421 at the lowermost end of the inner wall of the inner cylinder 4, and the second annular groove 42 is at the lowermost end. In actual operation, the second projection 222 at the lowermost end of the opener 200 engages with the second annular groove 42 at the lowermost end of the inner cylinder 4.

In accordance with the present invention, there is also provided a tubing string comprising a plurality of full-bore fracturing slips 100 and a plurality of conventional stepless slips. The plurality of full-bore fracturing slips 100 are connected in series and used in combination with a conventional stepless slip, thereby forming a working string, and the opening tool 200 can sequentially open and pass through the corresponding full-bore fracturing slips 100. The pipe column can meet the requirement of the transformation of unconventional oil and gas reservoirs.

According to the present invention, a method of operating the full-bore fracturing sleeve 100 is also provided. The following describes the operation of the full-bore fracturing sleeve 100 in detail with reference to fig. 4-six.

First, a plurality of full-path fracturing slips 100 are connected in series in a string, thereby forming a working string in cooperation with a plurality of conventional stepless slips. In the initial state, the full-path fracturing sleeve 100 is in the closed state.

And then, running the operation pipe column to the preset stratum.

When the full-bore fracturing slide sleeve 100 needs to be opened after the operation pipe column is in place, the opening tool 200 is put in from the wellhead, the opening tool 200 is pumped through the unmatched slide sleeve until the opening tool 200 stops moving when the matched full-bore fracturing slide sleeve 100 is entered. At this time, as shown in fig. 4, the ball seat portion 210 of the opener 200 forms a clearance fit with the lower sleeve 6, so that the liquid is throttled, thereby creating a pressure difference over and under the opener 200, and transmitting the axial pressure to the inner cylinder 4 through the first boss 221. When the pressure reaches the shearing critical value of the first shearing pin 5, the inner cylinder 4 shears the first shearing pin 5 and drives the lower sleeve 6 and the opening tool 200 to move downwards. Until the lower end surface of the lower sleeve 6 contacts the upper end surface of the lower joint 3, at this time, as shown in fig. 5, the lower sleeve 6 sits on the upper end surface of the lower joint 3 to form a limit. Thereby, the diversion holes 11 of the full-path fracturing sleeve 100 are opened.

After that, the inner cylinder 4 and the opener 200 together apply downward pressure, and when the pressure reaches the shearing threshold value of the second shearing pin 7, the inner cylinder 4 shears the second shearing pin 7 and moves downward. Under the action of the pressure difference, the inner cylinder 4 applies pressure to the third inclined surface 223 of the second boss 222 of the opening tool 200 through the first inclined surface 421 of the second annular groove 42, so that the elastic claw 220 is contracted radially inwards by utilizing the cooperation between the first inclined surface 421 and the second inclined surface 223, and the cooperation between the elastic claw 220 and the inner cylinder 4 is released, so that the opening tool 200 passes through the full-path fracturing sliding sleeve 100 under the action of the pump pressure. Fig. 6 schematically shows the structure of the opening tool 200 with the elastic claw 220 in a contracted state.

The opening tool 200 continues to pump through the first stage full-path fracturing sleeve 100 and then to the next stage full-path fracturing sleeve 100.

And repeating the steps until all the full-diameter fracturing sliding sleeves 100 in the tubular column are opened, and then performing subsequent operations. Thus, the plurality of stepless multi-cluster fracturing sliding sleeves are opened by one opening tool 200, so that the requirement of unconventional oil and gas reservoir reconstruction is met.

The full-drift-diameter fracturing sliding sleeve 100 is matched with a conventional stepless sliding sleeve to be used as a stepless multi-cluster fracturing sliding sleeve, and a plurality of stepless multi-cluster fracturing sliding sleeves can be opened by one opening tool 200 so as to meet the requirement of the transformation of an unconventional oil and gas reservoir. The operation method of the full-drift-diameter fracturing sliding sleeve is simple to operate, can greatly improve the opening efficiency of the sliding sleeve, can effectively ensure the success rate of opening the sliding sleeve, and is very beneficial to improving the operation efficiency of reservoir reconstruction of the oil and gas reservoirs.

In the present invention, it should be noted that the terms "first," "second," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more such feature. In the description of the present invention, the meaning of "a plurality" is two or more, unless explicitly defined otherwise.

In the present invention, unless explicitly specified and limited otherwise, the terms "mounted," "connected," "secured," and the like are to be construed broadly and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the above terms in the invention will be understood by those skilled in the art according to the specific circumstances.

In the description of the present specification, a description referring to terms "one embodiment," "some embodiments," "examples," "specific examples," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiments or examples. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

Finally, it should be noted that the above description is only of a preferred embodiment of the invention and is not to be construed as limiting the invention in any way. Although the invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that modifications may be made to the techniques described in the foregoing examples, or equivalents may be substituted for elements thereof. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (10)

1. A full-bore fracturing sleeve comprising:

the outer cylinder (1) is provided with a diversion hole (11) penetrating through the side wall of the outer cylinder;

an upper joint (2) and a lower joint (3) respectively connected with two ends of the outer cylinder;

an inner cylinder (4) concentrically arranged within the outer cylinder, the inner cylinder being fixed to the outer cylinder by a first shear pin (5);

the lower sleeve (6) is arranged at the lower end of the inner cylinder and is fixed with the inner cylinder through a second shear pin (7);

wherein the shearing critical value of the second shearing pin is larger than that of the first shearing pin,

the inner cylinder can be matched with the inner cylinder through a downward opening tool (200), the inner cylinder is driven to shear the first shearing pin through the action of pressure difference and then descends until the lower sleeve is propped against the upper end face of the lower joint to open the flow guide hole, the inner cylinder can shear the second shearing pin under the action of pressure and then continues descending, and the opening tool is contracted to pass through the full-diameter fracturing sliding sleeve.

2. The full-path fracturing sliding sleeve of claim 1, wherein the opening tool is configured to comprise a ball seat portion (210) and an elastic claw (220) fixedly connected to the upper end of the ball seat portion, the outer surface of the elastic claw is provided with a first protruding portion (221), the inner wall of the inner cylinder is provided with a first annular groove (41), and the first protruding portion can be matched with the first annular groove and transmit axial pressure.

3. The full-bore fracturing sliding sleeve of claim 2, wherein the inner wall of the inner barrel is further provided with a plurality of second annular grooves (42) which are uniformly distributed at intervals along the axial direction, the side wall surface of the second annular groove is configured into a first inclined surface (421), the outer surface of the elastic claw is provided with a plurality of second protruding parts (222) which can be matched with the second annular groove,

the inner cylinder can apply pressure to the upper end face of the second protruding part through the side wall of the second annular groove, so that the elastic claw radially contracts.

4. A full-bore fracturing sleeve according to claim 2 or 3, characterized in that the inner wall of the ball seat portion is configured with a conical surface (211) for adaptation to a pressure-holding ball.

5. The full-path fracturing slide sleeve of claim 1, wherein an outer wall of the lower sleeve is provided with an upwardly facing step (61), and an upper end portion of the lower sleeve is inserted into the inner barrel to be fixed with the inner barrel by a second shear pin and a space is formed between a lower end surface of the inner barrel and an end surface of the step.

6. The full bore frac sleeve of claim 5, wherein an upper end face of said lower sleeve is configured as a third chamfer (62).

7. The full-path fracturing slide sleeve of claim 1, wherein two first sealing members (8) are arranged between the inner cylinder and the outer cylinder in a spaced-apart manner, and when the diversion hole is closed, the diversion hole and the first shearing pin are positioned between the axial directions of the two first sealing members.

8. The full-path fracturing slide sleeve of claim 1, wherein the upper joint and the lower joint are both configured as step-shaped connecting buckles, and second sealing elements (9) are respectively arranged between connecting surfaces of the upper joint, the lower joint and the outer barrel.

9. A tubular string comprising a plurality of full-diameter fracturing tree sleeves according to any one of claims 1 to 8, a plurality of said full-diameter fracturing tree sleeves being in series, said opening tool being capable of sequentially opening and passing through respective ones of said full-diameter fracturing tree sleeves.

10. A method of operating a full path frac sleeve according to any one of claims 1 to 8, comprising the steps of:

step one: connecting a plurality of full-path fracturing sliding sleeves in series into a tubular column, and running the tubular column into a preset stratum;

step two: throwing the opening tool from a wellhead, and pumping the opening tool to the corresponding full-diameter fracturing sliding sleeve;

step three: the opening tool is matched with the inner cylinder, and drives the lower sleeve to descend after shearing the first shearing pin under the action of pressure difference, so that the diversion hole is opened;

step four: continuously pressurizing until the inner barrel shears the second shear pin, and enabling the inner barrel to shrink under the action of pressure difference, so that the opening tool passes through the corresponding full-diameter fracturing sliding sleeve and descends to the next stage of full-diameter fracturing sliding sleeve;

step five: and the opening tool repeats the third step and the fourth step until all the full-diameter fracturing sliding sleeves are opened.