CN117684937B - Cracking and staged fracturing method based on aerodynamic force impact fluid cracking and staged fracturing integrated device - Google Patents

Abstract

The invention discloses a aerodynamic force impact fluid cracking and staged fracturing integrated device and a method, wherein the device comprises the following components: the drilling machine is connected with the staged fracturing device through a high-pressure pipeline, the drainage pressure relief pipeline is connected with the high-pressure pipeline through a first tee joint, and the end A of the electromagnetic valve is connected with the high-pressure pipeline through a second tee joint; the high-pressure liquid injection pump station is connected with the end P of the electromagnetic valve through a high-pressure fluid pipeline; the high-pressure fluid pipeline is provided with a liquid injection switch and a high-pressure fluid pipeline pressure gauge; the high-pressure air power device is connected with the R end of the electromagnetic valve through a high-pressure air pipeline; the high-pressure gas pipeline is sequentially provided with a high-pressure gas tank and an aerodynamic switch; a stop pin is arranged on the high-pressure pipeline between the drilling machine and the first tee joint. The invention can control the cracking and fracturing by operating the control system; by designing an initial setting link of the capsule packer before the cracking, the capsule packer is prevented from being cracked due to high-pressure impact, and the aerodynamic impact cracking is realized; through multistage staged fracturing, the integral uniform fracturing of the coal stratum is realized.

Description

A fracturing and staged fracturing method based on an integrated device for fracturing and staged fracturing with a pneumatic impact fluid

Technical Field

The invention relates to the technical field of coal rock stratum fracturing, and in particular to an integrated device and method for pneumatic impact fluid fracturing and staged fracturing.

Background technique

Fracturing technology has been widely used in coal mine rock burst, coal and gas outburst, coal seam gas pressure relief and permeability enhancement, hard coal and rock softening control, hard rock tunnel excavation, etc. Compared with oil and gas and geothermal surface drilling hydraulic fracturing, coal mines are restricted by many factors such as operating environment, economic cost and operation time. The fracturing scale of underground coal mine drilling fracturing fluid injection volume and pressure is relatively small, and the fracturing technology and equipment are relatively small and simple. Chinese patent application CN101446187A discloses a double-packer hydraulic jet fracturing process, which realizes hydraulic jet fracturing through sandblasting perforation, sealing, hydraulic jet fracturing, pressure release and sand removal, and upper layer fracturing, thereby reducing the operation process of perforating bullet perforation, reducing the downhole operation tools of layered fracturing, and reducing the operation risk of drill sticking; however, with the gradual depletion of shallow coal resources, the shift to deep coal mining has become an inevitable trend. Under deep mining conditions, the ground stress, gas pressure, tectonic stress, and mining stress are greater. Traditional single fracturing technologies such as hydraulic fracturing and gas fracturing face increasing difficulties in the deep and complex coal and rock formation environment. It is very difficult to initiate fracturing cracks in a high ground stress environment, and blindly increasing the fluid pressure will have a negative impact on the pipeline, sealing, and fracturing safety, and will also greatly increase the fracturing cost.

The traditional explosive blasting has a small blasting fracturing range under the three-dimensional high ground stress environment, and is not suitable for scenes such as roof cutting and rock burst area control that require a single long crack. In addition, underground explosive blasting in coal mines is strictly controlled, has many restrictions, poor safety, and complex operation procedures. The "Coal Mine Safety Regulations" clearly stipulate that it is strictly forbidden to carry out explosive blasting pre-cracking in locations such as working face mining areas. Carbon dioxide phase change fracturing can better solve the problem of coal and rock strata cracking under high ground stress conditions, but this technology is mainly suitable for instantaneous phase change fracturing with a one-time fracturing tube. Usually, the fracturing range is very small, and high-pressure fluid injection cannot be continued after phase change fracturing; in addition, carbon dioxide phase change fracturing requires high-pressure carbon dioxide gas, which is relatively expensive. Due to the safety hazards in its storage and transportation process, and the instantaneous expansion of volume during the fracturing process, which shows the phenomenon of explosive blasting, it is strictly controlled by the public security and industry and information technology departments. In recent years, many scholars and field engineers have made a lot of improvements and attempts on perforation fracturing and hydraulic fracturing technology in coal mines. Chinese patent application CN114658429A discloses a high-temperature and high-pressure fluid in-hole circulation impact energy release advance pre-cracking rock breaking device and method, and Chinese patent application CN111608629A discloses a carbon dioxide pulse fracturing device and a fracturing method. The above two devices and methods do not cooperate with the fracturing operation in time after fracturing the coal rock mass, and the generated cracks are easily closed due to the influence of high ground stress, making it difficult to achieve the overall permeability and pressure relief of the coal rock layer; although various new fracturing and fracturing technologies have been proposed, various methods and devices do not combine the initial fracturing of cracks with the continuous expansion of cracks, and the capsule is easily damaged during the process of crack fracturing and sealing, resulting in poor sealing quality and difficulty in achieving the expected crack initiation and expansion effects.

Therefore, there is an urgent need to invent a new integrated technical device and method for impact fracturing and fracturing crack expansion of coal rock strata, so as to solve the problem of rapid and efficient fracturing of coal rock strata and continuous expansion of fracturing cracks, and at the same time adopt the invented reusable sealing device and method to realize segmented fracturing and fracturing of drilling holes, ensure the continuity of time and full coverage of space of underground drilling fracturing, and further promote the development of fracturing technology.

Summary of the invention

In order to quickly and efficiently complete segmented fracturing and hydraulic fracturing, and solve the problems of rapid and efficient fracturing of coal rock strata and continuous expansion of hydraulic fracturing cracks, the present invention proposes an integrated device and method for pneumatic impact fluid fracturing and segmented hydraulic fracturing, which not only combines fracturing with hydraulic fracturing, stably and efficiently realizes coal rock strata permeability increase and pressure relief, improves the hydraulic fracturing efficiency of the borehole, but also can effectively reduce the wear rate of the capsule packer and extend the service life of the packer.

In order to achieve the above technical objectives, the present invention adopts the following technical solutions:

An integrated device for pneumatic impact fluid fracturing and staged fracturing includes: a drilling rig, a control system, a drainage and pressure relief pipeline, a solenoid valve, a high-pressure injection pump station, a high-pressure pneumatic device, and a staged fracturing device. The drilling rig is connected to the staged fracturing device through a high-pressure pipeline, and a first tee and a second tee are sequentially arranged at one end of the high-pressure pipeline close to the drilling rig;

The drainage pressure relief pipeline is connected to the high-pressure pipeline through the first tee, a pressure relief switch is provided on the drainage pressure relief pipeline, and a drainage pressure relief pipeline pressure gauge is provided between the pressure relief switch and the first tee;

The A end of the solenoid valve is connected to the high-pressure pipeline through the second three-way connection;

The high-pressure liquid injection pump station is connected to the P end of the solenoid valve through a high-pressure fluid pipeline; a liquid injection switch and a high-pressure fluid pipeline pressure gauge are provided on the high-pressure fluid pipeline;

The high-pressure gas power device is connected to the R end of the solenoid valve through a high-pressure gas pipeline; a high-pressure gas tank, a first gas power switch, and a second gas power switch are sequentially arranged on the high-pressure gas pipeline;

A stop pin is provided on the high-pressure pipeline between the drilling rig and the first tee;

The control system is respectively connected with the high-pressure liquid injection pump station, the high-pressure gas power device, the solenoid valve, the liquid injection switch, the first gas power switch and the second gas power switch.

Preferably, the staged fracturing device includes two capsule packers sleeved on the high-pressure pipeline, a high-pressure steel pipe one-way valve is provided on the high-pressure pipeline between the two capsule packers, a packer one-way valve is provided on the high-pressure pipeline inside the capsule packer, and the capsule packer includes a double-layer expansion capsule sleeved on the high-pressure pipeline and fastening devices provided at both ends of the double-layer expansion capsule for fixing the double-layer expansion capsule.

Preferably, the fastening device includes a fixing with an embedded screw hole, a fastening ring, an anti-slip rubber pad and a fastening screw; the fixing includes a protruding fixing and a recessed fixing, the two ends of the double-layer expansion capsule are tightly pressed between the protruding fixing and the recessed fixing, an anti-slip rubber pad is provided between the recessed fixing and the high-pressure pipeline, the protruding fixing and the recessed fixing at one end of the fixing away from the one-way valve of the packer are fixedly connected by a fastening screw, and a fastening ring is provided on the outside of the protruding fixing at one end of the fixing close to the one-way valve of the packer.

Preferably, a centralizer is provided on the high-pressure pipeline between the second tee and the staged fracturing device.

The present invention also provides a fracturing and staged fracturing method of an integrated device for fracturing and staged fracturing using pneumatic impact fluid, comprising the following steps:

S1: Arrange drilling holes: Drill holes with preset lengths in the coal and rock layers using a drilling rig, and flush the holes with clean water to ensure that the hole walls are smooth;

S2: Equipment installation: The staged fracturing device and multiple sections of high-pressure pipelines are connected in sequence through the drilling rig, and the tail end of the high-pressure pipeline is fixed by the drilling rig;

S3: Carry out sealing test before fracturing: the solenoid valve is in the power-off state, the pressure relief switch and the stop pin are in the closed state, the A end and the P end of the solenoid valve are connected, and the main switch A, the high-pressure injection pump station switch B, and the injection switch F in the control system are turned on; after the trigger time T1, the high-pressure injection pump station starts to work, and the fluid gradually fills the inside of the high-pressure pipeline through the high-pressure fluid pipeline and the solenoid valve; when the reading of the high-pressure fluid pipeline pressure gauge reaches the sealing test pressure P1, close the high-pressure injection pump station switch B and the injection switch F in the control system. After the static time T2, if the high-pressure fluid pipeline pressure gauge reading P1 drops by no more than △P within the T2 time period, it indicates that the pipeline system is well sealed; if the high-pressure fluid pipeline pressure gauge reading P1 drops by more than △P within the T2 time period, the pipeline system needs to be repaired, and the pipeline sealing is tested again after the repair until the requirements are met;

S4: Initial setting of the packer: Turn on the high-pressure injection pump station switch B and the injection switch F in the control system. After the trigger time T1, the high-pressure injection pump station starts to work, and the fluid is continuously injected into the high-pressure pipeline through the high-pressure fluid pipeline and the solenoid valve; when the pressure gauge reading of the high-pressure fluid pipeline reaches the opening pressure _Pf1 of the packer check valve, the packer check valve is opened, and the capsule packer is gradually filled with fluid and continuously expands, and gradually fits tightly with the hole wall to form an annular closed space, achieving initial setting;

S5: Pneumatic impact fluid fracturing: turn off the high-pressure injection pump station switch B and the injection switch F in the control system, and turn on the high-pressure pneumatic device switch C and the solenoid valve switch E in the control system; after the trigger time T1, the solenoid valve is in the on state, the A end and the R end of the solenoid valve are connected, the high-pressure pneumatic device is turned on, and the high-pressure gas formed by the high-pressure pneumatic device enters the high-pressure gas tank; turn on the pneumatic switch D in the control system, after the trigger time T1, the first pneumatic switch and the second pneumatic switch on the high-pressure gas pipeline are turned on at the same time, and the high-pressure gas stored in the high-pressure gas tank is released instantly, impacting the fluid inside the high-pressure pipeline in a very short time, and the capsule packer is further fitted to the hole wall by the impact of the high-pressure fluid to complete the enhanced sealing, and the high-pressure steel pipe one-way valve in the middle of the staged fracturing device is instantly opened under the impact of the high-pressure gas, and the high-pressure fluid enters the annular closed space between the two capsule packers and the high-pressure pipeline, instantly breaking the coal rock mass, and realizing the high-pressure pneumatic impact fluid fracturing;

S6: Hydraulic fracturing: close the high-pressure gas power device switch C, gas power switch D and solenoid valve switch E of the control system. After the trigger time T1, the high-pressure gas power device, the first gas power switch, the second gas power switch and the solenoid valve are closed, and then the high-pressure injection pump station switch B and the injection switch F of the control system are opened; after the trigger time T1, the high-pressure injection pump station is opened, the A end and the P end of the solenoid valve are connected, and the high-pressure fluid enters the high-pressure pipeline. The fluid pressure in the high-pressure pipeline continues to increase. When the fluid pressure is greater than the opening pressure P _f2 of the high-pressure steel pipe one-way valve, the high-pressure steel pipe one-way valve is opened, and the high-pressure fluid enters the annular closed space between the two capsule packers and the high-pressure pipeline, so that the fracture initiation cracks expands, and the staged fracturing of the coal rock layer is realized;

S7: Standing and draining pressure relief: turn off the high-pressure injection pump station switch B, injection switch F, and main switch A of the control system in sequence. After the standing time T3, manually open the pressure relief switch to drain the liquid and relieve the pressure, and the capsule packer shrinks;

S8: Move the staged fracturing device a predetermined distance, repeat steps S4 to S7, and fracture the coal rock layer step by step from the inside to the outside, so that the coal rock layer in the axial range of the entire borehole is evenly fractured; after the fracturing of the entire borehole is completed, withdraw the high-pressure pipeline and the staged fracturing device from the coal rock layer.

Preferably, the magnitude relationship of each pressure is P _f2 >P _f1 >P ₁ , T1 is 10-15 s, T2 is 30 min, and T3 is 1.5 h.

Compared with the prior art, the present invention has the following beneficial effects:

The present invention can control the initiation of fracturing and fracturing only by operating the control system; by designing the initial setting link of the capsule packer before the initiation of fracturing, the capsule packer is prevented from being ruptured by high pressure impact, and the pneumatic impact fracturing is realized; through multi-stage fracturing, the uniform permeability enhancement fracturing of the entire coal rock layer is realized, and specifically, the advantages are as follows:

1. The present invention controls the solenoid valve through the control system to complete the switching of the fluid pipeline and the gas pipeline, realizing the integration of pneumatic impact fluid fracturing and hydraulic fracturing, which not only solves the problem that the existing hydraulic fracturing technology is difficult to initiate cracks, but also switches the high-pressure pipeline in time after impact fracturing, injects high-pressure fluid for fracturing, so that the initiated cracks continue to expand and increase the crack length, solves the problem that a single impact-initiated crack is easy to close under high ground stress and has a small impact range, and improves the impact fracturing and hydraulic fracturing effects;

2. The sealing detection link of the high-pressure pipeline system designed in the present invention can not only check the sealing of the pipeline, but also inject a set pressure fluid before impact cracking. The capsule packer is pre-filled with fluid and expands under pressure to achieve the initial sealing of the capsule packer, thereby greatly reducing the impact force on the capsule packer during the pneumatic impact cracking process, avoiding the problem that the capsule packer is easily damaged by impact, reducing the wear caused by the sliding of the capsule packer in the borehole during the impact process, and extending the service life of the packer;

3. In the present invention, the middle of the capsule packer is composed of two layers of expansion capsules that fit together. The two layers of expansion capsules have high toughness and wear resistance, which can prevent the expansion capsules from rubbing against the hole wall or directly contacting with the protruding tip on the hole wall during the sealing process and breaking, thereby ensuring the wear resistance and reusability of the capsule packer; an anti-slip rubber pad is provided between the fixing part of the expansion capsule and the high-pressure steel pipe to prevent the fixing part from sliding due to the impact of high-pressure fluid, and a fastening ring sleeved at one end of the fixing part can press the fixing part tightly against the high-pressure steel pipe to prevent the fixing part from falling off due to the impact of high pressure, thereby ensuring the firmness and reliability of the capsule packer;

4. The present invention can perform multi-stage fracturing in the axial direction of the coal rock formation borehole, and perform staged fracturing on the coal rock formation step by step from the inside to the outside, thereby achieving uniform fracturing in the entire borehole range.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to more clearly illustrate the embodiments of the present invention or the technical solutions of the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

FIG1 is a schematic diagram showing the overall layout of the integrated device for pneumatic impact fluid fracturing and staged fracturing according to the present invention.

FIG. 2 is a schematic diagram of a staged fracturing device.

FIG3 is a schematic diagram of the flow chart of the pneumatic impact fluid fracturing and staged fracturing method of the present invention.

FIG. 4 is a schematic diagram of a control system circuit of the present invention.

In the figure: 1, coal rock layer; 2, drilling rig; 3, control system; 4, high-pressure pipeline; 4-1, high-pressure fluid pipeline; 4-2, high-pressure gas pipeline; 4-3, drainage pressure relief pipeline; 5, high-pressure injection pump station; 6, high-pressure gas power device; 7, staged fracturing device; 7-1, high-pressure steel pipe one-way valve; 7-2, anti-slip rubber pad; 7-3, fastening screw; 7-4, fixing parts; 7-4-1, raised fixing parts; 7-4-2, recessed fixing parts ; 7-5, fastening ring; 7-6, double-layer expansion capsule; 7-7, packer one-way valve; 8, high-pressure gas tank; 9-1, first pneumatic switch; 9-2, second pneumatic switch; 10, solenoid valve; 11, injection switch; 12, high-pressure fluid pipeline pressure gauge; 13, stop pin; 14, drilling hole; 15-1, first three-way; 15-2, second three-way; 16, pressure relief switch; 17, drainage pressure relief pipeline pressure gauge; 18, centralizer.

Detailed ways

The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

As shown in FIG1-2, a pneumatic impact fluid fracturing and staged fracturing integrated device comprises: a drilling rig 2, a control system 3, a drainage pressure relief pipeline 4-3, a two-position three-way solenoid valve 10, a high-pressure injection pump station 5, a high-pressure pneumatic device 6, and a staged fracturing device 7. The drilling rig 2 is connected to the staged fracturing device 7 through a high-pressure pipeline 4, and a first three-way 15-1 and a second three-way 15-2 are sequentially arranged on the end of the high-pressure pipeline 4 close to the drilling rig 2; a centralizer 18 is arranged on the high-pressure pipeline 4 between the second three-way 15-2 and the staged fracturing device 7 to prevent the high-pressure pipeline 4 from sinking; the drainage pressure relief pipeline 4-3 is connected to the high-pressure pipeline 4 through the first three-way 15-1, a pressure relief switch 16 is arranged on the drainage pressure relief pipeline 4-3, and a drainage pressure relief pipeline pressure gauge 17 is arranged between the pressure relief switch 16 and the first three-way 15-1;

The end of the solenoid valve 10A is connected to the high-pressure pipeline 4 through the second three-way 15-2;

The high-pressure injection pump station 5 is connected to the electromagnetic valve 10P end through the high-pressure fluid pipeline 4-1; the high-pressure fluid pipeline 4-1 is provided with an injection switch 11 and a high-pressure fluid pipeline pressure gauge 12; the high-pressure injection pump station 5 continuously provides high-pressure fluids of different flow rates and pressures according to demand; the fluid is a liquid suitable for hydraulic fracturing of coal rock mass;

The high-pressure gas power device 6 is connected to the electromagnetic valve 10R end through the high-pressure gas pipeline 4-2; the high-pressure gas tank 8, the first gas power switch 9-1, and the second gas power switch 9-2 are arranged on the high-pressure gas pipeline 4-2 in sequence; the high-pressure gas power device 6 provides high-pressure gas of different volumes and pressures according to demand, so as to meet the demand for high-pressure gas impact fluid cracking; the maximum pressure provided by the high-pressure gas power device 6 is 50MPa, and the capacity of the high-pressure gas tank 8 is ^3m3 ;

A stop pin 13 is provided on the high-pressure pipeline 4 between the drilling rig 2 and the first tee 15-1; the stop pin 13 is used to block the fluid in the high-pressure pipeline 4 to prevent the fluid in the high-pressure pipeline 4 from flowing into the drilling rig 2;

The control system 3 is respectively connected to the high-pressure liquid injection pump station 5, the high-pressure gas power device 6, the solenoid valve 10, the liquid injection switch 11, the first gas power switch 9-1, and the second gas power switch 9-2. Figure 4 is a schematic diagram of the control system circuit of the present invention. The control system 3 is provided with 6 electromagnetic switches. Switch A is responsible for the connection and disconnection of the entire control system; switch B is responsible for the connection and disconnection of the high-pressure liquid injection pump station 5; switch C is responsible for the connection and disconnection of the high-pressure gas power device 6; switch D is responsible for the synchronous connection and disconnection of the first gas power switch 9-1 and the second gas power switch 9-2; switch E is responsible for the connection and disconnection of the solenoid valve 10; switch F is responsible for the connection and disconnection of the liquid injection switch 11.

The staged fracturing device 7 includes two capsule packers sleeved on the high-pressure pipeline 4. A high-pressure steel pipe check valve 7-1 is provided on the high-pressure pipeline 4 between the two capsule packers. The opening pressure of the high-pressure steel pipe check valve 7-1 is 10MPa. A packer check valve 7-7 is provided on the high-pressure pipeline 4 inside the capsule packer. The opening pressure of the packer check valve 7-7 is 5MPa. The capsule packer includes a double-layer expansion capsule 7-6 sleeved on the high-pressure pipeline 4 and a fastening device provided at both ends of the double-layer expansion capsule 7-6 for fixing the double-layer expansion capsule 7-6. The outer diameter of the double-layer expansion capsule 7-6 before expansion is 80mm. The high-pressure steel pipe check valve 7-1 slides axially along the high-pressure pipeline 4 to open. The opening pressure of the high-pressure steel pipe check valve 7-1 is greater than the packer check valve 7-7 and less than the high-pressure pneumatic impact pressure.

The fastening device includes a fixing part 7-4 with an embedded screw hole, a fastening ring 7-5, an anti-skid rubber pad 7-2 and a fastening screw 7-3; the fixing part 7-4 includes a protruding fixing part 7-4-1 and a recessed fixing part 7-4-2, both ends of the double-layer expansion capsule 7-6 are pressed tightly between the protruding fixing part 7-4-1 and the recessed fixing part 7-4-2 for fixation, an anti-skid rubber pad 7-2 is provided between the recessed fixing part 7-4-2 and the high-pressure pipeline 4, the protruding fixing part 7-4-1 and the recessed fixing part 7-4-2 at one end of the fixing part 7-4 away from the packer check valve 7-7 are fixedly connected by a fastening screw 7-3, and a fastening ring 7-5 is sleeved on the outer side of the protruding fixing part 7-4-1 at one end of the fixing part 7-4 close to the packer check valve 7-7.

The drilling rig 2 is a directional drilling rig, and the high-pressure liquid injection pump station 5 and the high-pressure gas power device 6 are respectively a fracturing pump station and an air compressor.

As shown in FIG3 , the present invention also provides a method for initiating and staged fracturing of an integrated device for initiating and staged fracturing with a pneumatic impact fluid, comprising the following steps:

S1: Arrange drilling holes: According to the actual situation on site and the requirements for fracturing of the coal rock layer, the diameter, length and angle of the drilling hole 14 are designed, and a drilling hole 14 with a length of 200m, an angle of 30° and a diameter of 100mm is drilled in the coal rock layer 1 by a directional drilling machine. The drilling hole 14 is flushed with clean water to ensure that the hole wall is smooth;

S2: Equipment installation: The staged fracturing device 7 and the multiple high-pressure pipelines 4 connected in sequence are lowered by a directional drilling rig, and the tail end of the high-pressure pipeline 4 is fixed by the directional drilling rig;

S3: Carry out sealing test before fracturing: the solenoid valve 10 is in the power-off state, the pressure relief switch 16 and the stop pin 13 are in the closed state, the A end and the P end of the solenoid valve 10 are connected, and the main switch A, the fracturing pump station switch B, and the injection switch F in the control system 3 are turned on; after the triggering time of 15s, the fracturing pump station starts to work, and the fluid gradually fills the inside of the high-pressure pipeline 4 through the high-pressure fluid pipeline 4-1 and the solenoid valve 10; when the reading of the high-pressure fluid pipeline pressure gauge 12 reaches the sealing test pressure of 2MPa, the fracturing pump station switch B and the injection switch F in the control system 3 are closed. After a standing time of 30min, if the reading of the high-pressure fluid pipeline pressure gauge 12 drops by no more than 0.5MPa within the 30min period, it indicates that the pipeline system is well sealed; if the reading of the high-pressure fluid pipeline pressure gauge 12 drops by more than 0.5MPa within the 30min period, the pipeline system needs to be overhauled, and the pipeline sealing is tested again after the overhaul until the requirements are met;

S4: Initial setting of the packer: Open the fracturing pump station switch B and the injection switch F in the control system 3. After the trigger time of 15s, the fracturing pump station starts to work, and the fluid is continuously injected into the high-pressure pipeline 4 through the high-pressure fluid pipeline 4-1 and the solenoid valve 10; when the reading of the high-pressure fluid pipeline pressure gauge 12 reaches the opening pressure of the packer check valve 7-7 of 5MPa, the packer check valve 7-7 is opened, and the capsule packer is gradually filled with fluid and continuously expands, and gradually fits tightly with the hole wall to form an annular closed space, realizing the initial setting; and it can also solve the problem that the expansion capsule is easily damaged by the instantaneous expansion directly under the impact of high-pressure pneumatic force;

S5: Pneumatic impact fluid fracturing: close the fracturing pump station switch B and the injection switch F in the control system 3, and open the air compressor switch C and the solenoid valve switch E of the control system 3; after the trigger time of 15s, the solenoid valve 10 is in the on state, the A end and the R end of the solenoid valve 10 are connected, the air compressor is turned on, and the high-pressure gas formed by the air compressor enters the high-pressure gas tank 8. After the pressure reaches 50MPa, the pneumatic switch D in the control system 3 is turned on. After the trigger time of 15s, the first pneumatic switch 9-1 and the second pneumatic switch 9-2 on the high-pressure gas pipeline 4-2 are turned on at the same time, and the high-pressure gas stored in the high-pressure gas tank 8 is released instantly, impacting the fluid inside the high-pressure pipeline 4 in a very short time. The capsule packer is further fitted to the hole wall by the impact of the high-pressure fluid to complete the enhanced setting. The high-pressure steel pipe one-way valve 7-1 in the middle of the staged fracturing device 7 is instantly opened under the impact of the high-pressure gas, and the high-pressure fluid enters the annular closed space between the two capsule packers and the high-pressure pipeline 4, instantly breaking the coal rock mass, and realizing the high-pressure pneumatic impact fluid fracturing;

S6: Hydraulic fracturing: turn off the air compressor switch C, pneumatic switch D and solenoid valve switch E of the control system 3. After the trigger time of 15s, the air compressor, the first pneumatic switch 9-1, the second pneumatic switch 9-2 and the solenoid valve 10 are turned off, and then the fracturing pump station switch B and the injection switch F of the control system 3 are turned on; after the trigger time of 15s, the fracturing pump station is turned on, the A end and the P end of the solenoid valve 10 are connected, and the high-pressure fluid enters the high-pressure pipeline 4. The fluid pressure in the high-pressure pipeline 4 continues to increase. When the reading of the high-pressure fluid pipeline pressure gauge 12 is greater than the opening pressure of the high-pressure steel pipe one-way valve 7-1 of 10MPa, the high-pressure steel pipe one-way valve 7-1 is opened, and the high-pressure fluid enters the annular closed space between the two capsule packers and the high-pressure pipeline 4, so that the fracture initiation cracks expands, and the staged fracturing of the coal rock layer 1 is realized;

S7: Standing and draining pressure relief: turn off the fracturing pump station switch B, injection switch F, and main switch A of the control system 3 in sequence. After a standing time of 1.5 hours, manually open the pressure relief switch 16 to drain the pressure relief and shrink the capsule packer.

S8: Move the staged fracturing device 7 backward by 10m, and repeat steps S4 to S7, fracturing the coal rock layer 1 step by step from the inside to the outside, so that the coal rock layer 1 in the axial range of the entire borehole 14 is evenly fractured; after the fracturing of the entire borehole 14 is completed, the high-pressure pipeline 4 and the staged fracturing device 7 are withdrawn from the coal rock layer 1.

Claims (5)

1. A fracturing and staged fracturing method based on an integrated device for fracturing with pneumatic impact fluid and staged fracturing, characterized in that: the integrated device for fracturing with pneumatic impact fluid and staged fracturing comprises: a drilling rig (2), a control system (3), a drainage and pressure relief pipeline (4-3), a solenoid valve (10), a high-pressure injection pump station (5), a high-pressure pneumatic device (6), and a staged fracturing device (7), characterized in that: the drilling rig (2) is connected to the staged fracturing device (7) via a high-pressure pipeline (4), and a first tee (15-1) and a second tee (15-2) are sequentially arranged at one end of the high-pressure pipeline (4) close to the drilling rig (2); The drainage pressure relief pipeline (4-3) is connected to the high-pressure pipeline (4) via a first tee (15-1); a pressure relief switch (16) is provided on the drainage pressure relief pipeline (4-3); and a drainage pressure relief pipeline pressure gauge (17) is provided between the pressure relief switch (16) and the first tee (15-1); The A end of the solenoid valve (10) is connected to the high-pressure pipeline (4) via a second three-way connection (15-2); The high-pressure liquid injection pump station (5) is connected to the P end of the electromagnetic valve (10) through the high-pressure fluid pipeline (4-1); the high-pressure fluid pipeline (4-1) is provided with a liquid injection switch (11) and a high-pressure fluid pipeline pressure gauge (12); The high-pressure gas power device (6) is connected to the R end of the electromagnetic valve (10) through a high-pressure gas pipeline (4-2); a high-pressure gas tank (8), a first gas power switch (9-1), and a second gas power switch (9-2) are sequentially arranged on the high-pressure gas pipeline (4-2); A stop pin (13) is provided on the high-pressure pipeline (4) between the drilling machine (2) and the first tee (15-1); The control system (3) is respectively connected to the high-pressure liquid injection pump station (5), the high-pressure pneumatic device (6), the solenoid valve (10), the liquid injection switch (11), the first pneumatic switch (9-1), and the second pneumatic switch (9-2); The initiation and staged fracturing method includes the following steps: S1: Arranging drilling holes: drilling a borehole (14) of a preset length in a coal rock layer (1) by means of a drilling machine (2), and flushing the borehole (14) with clean water to ensure that the hole wall is smooth; S2: Equipment installation: The staged fracturing device (7) and the multiple high-pressure pipelines (4) connected in sequence are lowered through the drilling rig (2), and the tail end of the high-pressure pipeline (4) is fixed through the drilling rig (2); S3: Perform a sealing test before fracturing: the solenoid valve (10) is in a power-off state, the pressure relief switch (16) and the stop pin (13) are in a closed state, the A end and the P end of the solenoid valve (10) are connected, and the main switch A, the high-pressure injection pump station switch B, and the injection switch F in the control system (3) are turned on; after the trigger time T1, the high-pressure injection pump station (5) starts to work, and the fluid gradually fills the high-pressure pipeline (4) through the high-pressure fluid pipeline (4-1) and the solenoid valve (10); when the high-pressure fluid pipeline pressure is When the reading of the pressure gauge (12) reaches the sealing test pressure P1, the high-pressure injection pump station switch B and the injection switch F in the control system (3) are closed. After a static time T2, if the reading P1 of the high-pressure fluid pipeline pressure gauge (12) does not drop by more than △P within the T2 time period, it indicates that the pipeline system is in good sealing condition; if the reading P1 of the high-pressure fluid pipeline pressure gauge (12) drops by more than △P within the T2 time period, it is necessary to overhaul the pipeline system, and after the overhaul, the pipeline sealing is tested again until the requirements are met; S4: Initial sealing of the packer: the high-pressure injection pump station switch B and the injection switch F in the control system (3) are turned on. After the trigger time T1, the high-pressure injection pump station (5) starts to work, and the fluid is continuously injected into the high-pressure pipeline (4) through the high-pressure fluid pipeline (4-1) and the electromagnetic valve (10); when the reading of the high-pressure fluid pipeline pressure gauge (12) reaches the opening pressure P _f1 of the packer check valve (7-7), the packer check valve (7-7) is opened, and the capsule packer is gradually filled with fluid and continuously expands, and gradually fits tightly with the hole wall to form an annular closed space, thereby achieving initial sealing; S5: Pneumatic impact fluid cracking: close the high-pressure liquid injection pump station switch B and the liquid injection switch F in the control system (3), and open the high-pressure gas power device switch C and the electromagnetic valve switch E in the control system (3); after the trigger time T1, the electromagnetic valve (10) is in the on state, the A end and the R end of the electromagnetic valve (10) are connected, the high-pressure gas power device (6) is opened, and the high-pressure gas formed by the high-pressure gas power device (6) enters the high-pressure gas tank (8); open the gas power switch D in the control system (3), and after the trigger time T1, the first high-pressure gas pipeline (4-2) on the high-pressure gas pipeline (4-2) is opened. The pneumatic switch (9-1) and the second pneumatic switch (9-2) are turned on simultaneously, and the high-pressure gas stored in the high-pressure gas tank (8) is released instantly, impacting the fluid inside the high-pressure pipeline (4) in a very short time. The capsule packer is further fitted to the hole wall by the impact of the high-pressure fluid to complete the enhanced sealing. The high-pressure steel pipe one-way valve (7-1) in the middle of the staged fracturing device (7) is opened instantly under the impact of the high-pressure gas, and the high-pressure fluid enters the annular closed space between the two capsule packers and the high-pressure pipeline (4), instantly breaking the coal rock mass, and realizing the high-pressure pneumatic impact fluid fracturing; S6: hydraulic fracturing: close the high-pressure pneumatic device switch C, pneumatic switch D and electromagnetic valve switch E of the control system (3); after the trigger time T1, the high-pressure pneumatic device (6), the first pneumatic switch (9-1), the second pneumatic switch (9-2) and the electromagnetic valve (10) are closed, and then the high-pressure injection pump station switch B and the injection switch F of the control system (3) are opened; after the trigger time T1, the high-pressure injection pump station (5) is opened, the A end and the P end of the electromagnetic valve (10) are connected, and the high-pressure fluid enters the high-pressure pipeline (4). The fluid pressure in the high-pressure pipeline (4) continues to increase. When the fluid pressure is greater than the opening pressure P _f2 of the high-pressure steel pipe check valve (7-1), the high-pressure steel pipe check valve (7-1) is opened, and the high-pressure fluid enters the closed space between the two capsule packers and the high-pressure pipeline (4), so that the fracture initiation cracks expand, thereby realizing the staged fracturing of the coal rock layer (1); S7: Standing and draining to relieve pressure: turn off the high-pressure injection pump station switch B, injection switch F, and main switch A of the control system (3) in sequence, and after a standing time T3, manually open the pressure relief switch (16) to drain and relieve pressure, and the capsule packer shrinks; S8: Move the segmented fracturing device (7) a predetermined distance, repeat steps S4 to S7, and fracture the coal rock layer (1) step by step from the inside to the outside, so that the coal rock layer (1) in the axial range of the entire borehole (14) is evenly fractured; after the fracturing of the entire borehole (14) is completed, the high-pressure pipeline (4) and the segmented fracturing device (7) are withdrawn from the coal rock layer (1). 2. The fracturing and staged fracturing method based on the integrated device of pneumatic impact fluid fracturing and staged fracturing according to claim 1 is characterized in that the staged fracturing device (7) includes two capsule packers sleeved on the high-pressure pipeline (4), a high-pressure steel pipe one-way valve (7-1) is provided on the high-pressure pipeline (4) between the two capsule packers, a packer one-way valve (7-7) is provided on the high-pressure pipeline (4) inside the capsule packer, and the capsule packer includes a double-layer expansion capsule (7-6) sleeved on the high-pressure pipeline (4) and fastening devices provided at both ends of the double-layer expansion capsule (7-6) for fixing the double-layer expansion capsule (7-6). 3. The fracturing and staged fracturing method based on the integrated device for fracturing and staged fracturing with pneumatic impact fluid according to claim 2 is characterized in that the fastening device comprises a fixing member (7-4) with an embedded screw hole, a fastening ring (7-5), an anti-slip rubber pad (7-2) and a fastening screw (7-3); the fixing member (7-4) comprises a protruding fixing member (7-4-1) and a recessed fixing member (7-4-2), and both ends of the double-layer expansion capsule (7-6) are tightly pressed on the protruding fixing member (7-4-1) and the recessed fixing member (7-4-2). The recessed fixing member (7-4-2) is fixed between the recessed fixing member (7-4-2), an anti-slip rubber pad (7-2) is provided between the recessed fixing member (7-4-2) and the high-pressure pipeline (4), a raised fixing member (7-4-1) and a recessed fixing member (7-4-2) at one end of the fixing member (7-4) away from the packer check valve (7-7) are fixedly connected by a fastening screw (7-3), and a fastening ring (7-5) is sleeved on the outer side of the raised fixing member (7-4-1) at one end of the fixing member (7-4) close to the packer check valve (7-7). 4. The fracturing and staged fracturing method based on the integrated device for fracturing and staged fracturing using pneumatic impact fluid according to claim 1 is characterized in that a centralizer (18) is provided on the high-pressure pipeline (4) between the second tee (15-2) and the staged fracturing device (7). 5. The method for initiation and staged fracturing based on the integrated device for initiation and staged fracturing using pneumatic impact fluid according to claim 1, characterized in that the magnitude relationship of each pressure is _Pf2 > _Pf1 > _P1 , T1 is 10-15s, T2 is 30min, and T3 is 1.5h.