Coal mine hydraulic fracturing automatic control equipment system and using method thereof

Abstract

The invention belongs to the technical field of coal mine hydraulic fracturing, and particularly relates to a coal mine hydraulic fracturing automatic control equipment system and a using method thereof. The equipment system comprises a fracturing assembly, a high-pressure rubber pipe, a pressure pump and a water tank. The pressure pump comprises a pressure sensor, a flow sensor, an automatic control system, a frequency converter and a main motor. The pressure sensor and the flow sensor are respectively connected with an automatic control system which is connected with a frequency converter which is connected with a main motor. A data analysis unit and an instruction output unit are arranged in the automatic control system; the pressure sensor and the flow sensor transmit data to the data analysis unit, the data analysis unit analyzes and recognizes the water injection pressure and the water injection flow, and according to the recognition result, the instruction output unit conducts rapid frequency conversion and stepless speed regulation on a fracturing pump set main motor through the frequency converter, so that automatic control over the hydraulic fracturing process is achieved. Manual intervention is not needed, the hydraulic fracturing time is accurate, and construction blindness is reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of coal mine hydraulic fracturing, and in particular relates to a coal mine hydraulic fracturing automatic control equipment system and a use method thereof. Background Art

[0002] During coal mining, geological structures, ground stress, and the physical and chemical properties of coal and rock masses pose threats of rock bursts, dust, and gas. To prevent rock bursts, dust, and gas hazards, coal mines often use hydraulic fracturing technology to pre-treat the coal. First, hydraulic fracturing weakens the coal structure, blocking stress transmission and preventing rock bursts. Second, the hydraulic fracturing process effectively wets the coal, increasing its moisture content and preventing dust hazards. Finally, hydraulic fracturing expands the primary pore and fracture structure of the coal, complicating its pores and fractures, promoting gas extraction and addressing coal mine gas hazards.

[0003] Traditional hydraulic fracturing technology involves placing a water injection string into a coal seam borehole and injecting high-pressure water into the borehole. However, this traditional fracturing process has a significant problem: the length of a coal body hydraulic fracturing borehole is typically tens to hundreds of meters, and the coal body is a porous medium. During the hydraulic fracturing process, the water injected into the borehole will be lost in large quantities along the primary pores and fissures in the coal body, a phenomenon known as filtration. This prevents the water pressure inside the borehole from reaching the initiation pressure, resulting in poor fracturing results. With technological advances and equipment upgrades, staged hydraulic fracturing technology and equipment have been developed to address this issue. Staged fracturing has been replaced by a staged fracturing assembly consisting of a guide bevel, a check valve, and a packer, shortening the distance required for a single fracturing cycle. During use, the fracturing assembly is first pushed to the bottom of the hole for a single fracturing cycle. After the single fracturing cycle is completed, the fracturing assembly is moved a certain distance toward the orifice and fracturing is repeated. This process is repeated until the entire borehole is fully fractured. Staged fracturing effectively solves the filtration problem of hydraulic fracturing in coal seams, promotes the fracturing effect of hydraulic fracturing, and makes the pores and fissures in the coal body more complex. However, staged hydraulic fracturing has a problem: the output pressure and flow of the fracturing pump cannot be adjusted quickly and accurately.

[0004] At present, the hydraulic transmission shifting method is generally used to achieve the speed and torque adjustment of the fracturing pump. It is divided into neutral and 1-5 gears, and adopts a step-by-step shifting method. Gear shifting can only be performed when the transmission oil temperature and oil level meet specific requirements. Each gear shift requires a time interval of more than 15 seconds, and each gear corresponds to a fixed speed and torque. It is impossible to achieve fast, accurate and smooth adjustment of water injection volume and fracturing pressure, and it is even impossible to achieve automatic control of output pressure and flow during the fracturing process.

[0005] Therefore, it is necessary to upgrade and transform the staged fracturing equipment, and design and develop an automatic control equipment system for coal mine hydraulic fracturing based on the two key parameters of coal body fracturing pressure and water injection pressure. Summary of the Invention

[0006] The technical problem to be solved by this invention is to provide an automatic control system for hydraulic fracturing in coal mines and its use method. This system can effectively identify coal fracture initiation and automatically control the shutdown of staged hydraulic fracturing. The method is simple and easy to operate, saving water, manpower, and material resources, and meeting the needs of on-site hydraulic fracturing operations to the greatest extent possible.

[0007] The technical solutions adopted are:

[0008] A coal mine hydraulic fracturing automatic control equipment system includes a fracturing assembly, a high-pressure hose, a pressure pump and a water tank, which are connected in sequence. The pressure pump includes a pressure sensor, a flow sensor, an automatic control system, a frequency converter and a main motor.

[0009] The pressure sensor and flow sensor are respectively connected to the automatic control system, the automatic control system is connected to the frequency converter, and the frequency converter is connected to the main motor; a data analysis unit and an instruction output unit are set in the automatic control system; the pressure sensor and flow sensor transmit data to the data analysis unit, the data analysis unit analyzes and identifies the injection pressure and injection flow, and according to the identification results, the instruction output unit quickly changes the frequency and performs stepless speed regulation on the main motor of the fracturing pump group through the frequency converter, thereby realizing automatic control of the hydraulic fracturing process.

[0010] Preferably, the fracturing assembly includes a guide bend, a check valve, a packer, a choke, a safety release and a fracturing string, and the guide bend, the check valve, the packer, the choke, the packer, the safety release and the fracturing string are connected in sequence.

[0011] Preferably, the fracturing string is connected to a high-pressure hose via a union.

[0012] Preferably, the guide is installed at the front end, and the tail end of the guide is connected to the one-way valve through a nut buckle; both ends of the one-way valve are nut buckles, the upper end is connected to the guide, and the lower end is connected to the packer;

[0013] Preferably, the packer includes an upper packer and a lower packer, each packer includes a connecting pipe, a sliding sleeve, a sealing capsule, and a fixed lower head, wherein the capsule is connected to the sliding sleeve and the fixed lower head and covers the connecting pipe, and there is a circular hole in the connecting pipe near the fixed lower head. During the hydraulic fracturing process, the liquid enters the enclosed space between the sealing capsule and the connecting pipe through the circular hole. When the pressure reaches 2MPa, the sealing capsule is forced to pull the sliding sleeve to expand and seal the borehole; each packer has a nut buckle at both ends, wherein one end of the upper packer is connected to the one-way valve, and the other end is connected to the throttle; one end of the lower packer is connected to the throttle, and the other end is connected to the safety release.

[0014] Preferably, the throttle body is a circular steel tube with three gaps in the middle and nuts at both ends, one end connected to the upper packer and the other end connected to the lower packer; during the hydraulic fracturing process, the liquid causes the packers at both ends of the throttle to expand and the liquid enters the fracturing space formed by the packer and the borehole wall through the three gaps.

[0015] Preferably, the pressure sensor and flow sensor are installed on the pipeline between the high-pressure hose and the pressure pump.

[0016] Preferably, the data analysis unit has feedback and adjustment functions. The data analysis unit sets the initial cracking pressure threshold, analyzes and identifies the real-time data fed back by the pressure sensor and flow sensor, and then makes graded adjustments to form graded adjustment thresholds, and then outputs instructions for feedback. Specifically:

[0017] Set the initial fracturing pressure threshold, analyze the actual operation situation (using storage unit data), determine the water injection pressure output mode through pattern recognition, form a matching pressure output mode during operation, and then form a graded adjustment threshold to form instruction output feedback.

[0018] Preferably, the instruction output unit receives instruction output feedback, and performs rapid frequency conversion and stepless speed regulation on the main motor of the fracturing pump group by adjusting the frequency converter, and outputs the command to automatically control the fracturing process.

[0019] A method for using a coal mine hydraulic fracturing automatic control equipment system comprises the following steps:

[0020] (1) Install the fracturing components in sequence, connect the fracturing string to the high-pressure hose through the union, and then connect the pressure pump and water tank in sequence, and push the connected fracturing components to the bottom of the borehole with the help of a directional drilling rig;

[0021] (2) starting the fracturing pump and setting the initial fracturing pressure threshold of the automatic control system;

[0022] (3) Perform water injection fracturing; the automatic control system receives real-time data from the pressure sensor and flow sensor, and the data analysis unit analyzes and identifies the water injection pressure and water injection flow, then performs graded adjustment to form graded adjustment thresholds, and finally outputs instructions for feedback;

[0023] (4) The command output unit receives command output feedback and adjusts the frequency converter to quickly change the frequency and stepless speed of the main motor of the fracturing pump group, outputs and automatically controls the fracturing process, such as automatic control of water injection pressure and flow rate, and automatic shutdown.

[0024] Compared with the prior art, the present invention is beneficial in that:

[0025] The present invention provides an automatic control system for coal mine hydraulic fracturing and its use method. During the hydraulic fracturing process, the system analyzes injection pressure and flow rate data in real time and automatically controls the shutoff and shutdown of the fracturing pump based on the set minimum coal fracture initiation pressure and pressure drop data. This eliminates the need for manual intervention, accurately timed the hydraulic fracturing, and reduces the risk of blind operation.

[0026] The fracturing assembly is connected to a safety release. If a hole collapse occurs and the fracturing assembly cannot be fully withdrawn from the borehole, the ball will hit the release, breaking the T-shaped buckle in the center of the release. This allows all components connected to the safety release to be withdrawn from the borehole, reducing equipment costs. The high-pressure hose and fracturing string are connected via a union, which is convenient and leak-proof. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a structural diagram of an automatic control equipment system for hydraulic fracturing in coal mines implemented by the present invention;

[0028] Figure 2 This is a schematic diagram of the automatic control system in the fracturing pump;

[0029] Figure 3 This is the control flow chart of the automatic control system in the fracturing pump.

[0030] In the figure, 1-guide pipe, 2-check valve, 3-upper packer, 4-choke, 5-lower packer, 6-safety release, 7-fracturing string, 8-high-pressure hose, 9-fracturing pump, 10-water tank, 11-pressure sensor, 12-flow sensor, 13-automatic control system, 14-frequency converter, 15-main motor, 16-union joint. DETAILED DESCRIPTION

[0031] The accompanying drawings are for illustrative purposes only and are intended to facilitate the description and simplify the present invention. They are not to be construed as limiting the present invention. To further clarify the objectives, technical solutions, and beneficial effects of the present invention, the present invention is further described below in conjunction with specific embodiments and with reference to the accompanying drawings. Any unspecified areas are consistent with conventional practices in the prior art. Unless otherwise specified, the electrical components used in the present invention are available for purchase through conventional channels.

[0032] Example 1

[0033] like Figure 1 As shown, a coal mine hydraulic fracturing automatic control equipment system includes a fracturing component, a high-pressure hose 8, a pressure pump 9 and a water tank 10. The fracturing component, the high-pressure hose 8, the pressure pump 9 and the water tank 10 are connected in sequence. The pressure pump includes a pressure sensor 11, a flow sensor 12, an automatic control system 13, a frequency converter 14 and a main motor 15.

[0034] The fracturing assembly includes a guide 1, a check valve 2, a packer, a choke 4, a safety release 6 and a fracturing string 7, which are connected in sequence. The fracturing string 7 is connected to a high-pressure hose 8 through a union 16.

[0035] The guide 1 is installed at the front end, and the tail end of the guide 1 is connected to the one-way valve 2 through a nut buckle; the two ends of the one-way valve 2 are nut buckles, the upper end is connected to the guide 1, and the lower end is connected to the packer;

[0036] The packer includes an upper packer 3 and a lower packer 5, each packer includes a connecting pipe, a sliding sleeve, a sealing capsule, and a fixed lower head, wherein the capsule is connected to the sliding sleeve and the fixed lower head and covers the connecting pipe, and there is a circular hole in the connecting pipe near the fixed lower head. During the hydraulic fracturing process, the liquid enters the enclosed space between the sealing capsule and the connecting pipe through the circular hole. When the pressure reaches 2MPa, the sealing capsule is forced to pull the sliding sleeve to expand and seal the borehole; each packer has a nut buckle at both ends, wherein one end of the upper packer 3 is connected to the one-way valve 2, and the other end is connected to the throttle 4; one end of the lower packer 5 is connected to the throttle 4, and the other end is connected to the safety release 6.

[0037] The main body of the throttle 4 is a circular steel tube with three gaps in the middle and nuts at both ends. One end is connected to the upper packer 3 and the other end is connected to the lower packer 5. During the hydraulic fracturing process, the liquid expands the packers at both ends of the throttle 4 and enters the fracturing space formed by the packer and the borehole wall through the three gaps.

[0038] like Figure 2 As shown, the pressure sensor 11 and flow sensor 12 are installed in the pipeline between the high-pressure hose 8 and the pressure pump 9. These sensors are each connected to an automatic control system 13, which is in turn connected to a frequency converter 14, which is in turn connected to a main motor 15. Automatic control system 13 includes a data analysis unit and a command output unit. The pressure sensor 11 and flow sensor 12 transmit data to the data analysis unit, which analyzes and identifies the injection pressure and flow rate. Based on the identified results, the command output unit rapidly changes the frequency and performs stepless speed regulation on the main motor of the fracturing pump unit via the frequency converter 14, achieving automatic control of the hydraulic fracturing process.

[0039] As a further preference, the data analysis unit has feedback and adjustment functions. The data analysis unit sets the initial cracking pressure threshold, analyzes and identifies the real-time data fed back by the pressure sensor 11 and the flow sensor 12, and then makes graded adjustments to form graded adjustment thresholds, and then outputs instructions for feedback. Specifically:

[0040] Set the initial fracturing pressure threshold, analyze the actual operation situation (using storage unit data), determine the water injection pressure output mode through pattern recognition, form a matching pressure output mode during operation, and then form a graded adjustment threshold to form instruction output feedback.

[0041] The command output unit receives command output feedback, and performs rapid frequency conversion and stepless speed regulation on the main motor of the fracturing pump group by adjusting the frequency converter, and outputs the command to automatically control the fracturing process.

[0042] A method for using a coal mine hydraulic fracturing automatic control equipment system comprises the following steps:

[0043] (1) Install the fracturing components in sequence. Connect the fracturing string 7 to the high-pressure hose 8 through the union 16, and then connect it to the pressure pump 9 and the water tank 10 in sequence. Then, push the connected fracturing components to the bottom of the borehole with the help of a directional drilling rig.

[0044] The automatic control system 13 in the pressure pump 9 controls as follows Figure 3 As shown,

[0045] (2) Start the pressure pump 9 and set the initial cracking pressure threshold of the automatic control system 13;

[0046] (3) Performing water injection fracturing; the automatic control system 13 receives real-time data from the pressure sensor 11 and the flow sensor 12, and the data analysis unit analyzes and identifies the water injection pressure and water injection flow, then performs graded adjustment to form graded adjustment thresholds, and finally outputs instructions for feedback;

[0047] (4) The command output unit receives command output feedback, and adjusts the frequency converter to quickly change the frequency and output stepless speed regulation of the main motor of the fracturing pump group, automatically controls the fracturing process, adjusts the injection pressure and flow rate, and automatically shuts down.

[0048] Of course, the above description is not a limitation of the present invention, and the present invention is not limited to the above examples. Changes, modifications, additions or substitutions made by technicians in this technical field within the essential scope of the present invention should also fall within the scope of protection of the present invention.

Claims

1. A coal mine hydraulic fracturing automatic control equipment system, comprising a fracturing assembly, a high-pressure hose, a pressure pump and a water tank, wherein the fracturing assembly, the high-pressure hose, the pressure pump and the water tank are connected in sequence, characterized in that: The pressure pump includes a pressure sensor, a flow sensor, an automatic control system, a frequency converter and a main motor; The pressure sensor and flow sensor are respectively connected to the automatic control system, the automatic control system is connected to the frequency converter, and the frequency converter is connected to the main motor; a data analysis unit and a command output unit are arranged in the automatic control system; the pressure sensor and flow sensor transmit data to the data analysis unit, the data analysis unit analyzes and identifies the injection pressure and injection flow, and according to the identification result, the command output unit quickly changes the frequency and performs stepless speed regulation on the main motor of the fracturing pump group through the frequency converter, so as to realize automatic control of the hydraulic fracturing process.

2. A coal mine hydraulic fracturing automatic control equipment system according to claim 1, characterized in that: The fracturing assembly comprises a guide, a check valve, a packer, a choke, a safety release and a fracturing string, and the guide, the check valve, the packer, the choke, the packer, the safety release and the fracturing string are connected in sequence.

3. A coal mine hydraulic fracturing automatic control equipment system according to claim 2, characterized in that: The fracturing pipe string is connected to a high-pressure hose via a union joint.

4. A coal mine hydraulic fracturing automatic control equipment system according to claim 2, characterized in that: The guide is installed at the front end, and the tail end of the guide is connected to the one-way valve through a nut buckle; both ends of the one-way valve are nut buckles, the upper end is connected to the guide, and the lower end is connected to the packer.

5. The automatic control equipment system for hydraulic fracturing in coal mines according to claim 2, characterized in that: The packer includes an upper packer and a lower packer, each packer includes a connecting pipe, a sliding sleeve, a sealing capsule, and a fixed lower head, wherein the capsule is connected to the sliding sleeve and the fixed lower head and covers the connecting pipe, and there is a circular hole in the connecting pipe near the fixed lower head. During the hydraulic fracturing process, liquid enters the enclosed space between the sealing capsule and the connecting pipe through the circular hole. When the pressure reaches 2MPa, the sealing capsule is forced to pull the sliding sleeve to expand and seal the borehole; both ends of each packer are nut buckles, wherein one end of the upper packer is connected to the one-way valve, and the other end is connected to the throttle; one end of the lower packer is connected to the throttle, and the other end is connected to the safety release.

6. A coal mine hydraulic fracturing automatic control equipment system according to claim 5, characterized in that: The throttle body is a circular steel tube with three gaps in the middle and nuts at both ends, one end of which is connected to the upper packer and the other end is connected to the lower packer. During the hydraulic fracturing process, the liquid expands the packers at both ends of the throttle and enters the fracturing space formed by the packer and the borehole wall through the three gaps.

7. The automatic control equipment system for hydraulic fracturing in coal mines according to claim 1, characterized in that: The pressure sensor and flow sensor are installed on the pipeline between the high-pressure rubber hose and the pressure pump.

8. The automatic control equipment system for hydraulic fracturing in coal mines according to claim 1, characterized in that: The data analysis unit sets the initial crack initiation pressure threshold, analyzes and identifies the real-time data fed back by the pressure sensor and the flow sensor, and then makes graded adjustments to form graded adjustment thresholds, and then outputs instructions for feedback.

9. The coal mine hydraulic fracturing automatic control equipment system according to claim 8, characterized in that: The command output unit receives command output feedback, and outputs fast frequency conversion and stepless speed regulation of the main motor of the fracturing pump group by adjusting the frequency converter, thereby automatically controlling the fracturing process.

10. A method for using a coal mine hydraulic fracturing automatic control equipment system according to any one of claims 1 to 9, characterized in that: The steps include: (1) Install the fracturing components in sequence, connect the fracturing string to the high-pressure hose through the union, and then connect the pressure pump and the water tank in sequence, and push the connected fracturing components to the bottom of the borehole with the help of a directional drilling rig; (2) starting the pressure pump and setting the initial cracking pressure threshold of the automatic control system; (3) Perform water injection fracturing; the automatic control system receives real-time data from the pressure sensor and flow sensor, and the data analysis unit analyzes and identifies the water injection pressure and water injection flow, and then performs graded adjustment to form a graded adjustment threshold, and finally outputs a command feedback; (4) The command output unit receives command output feedback, and outputs fast frequency conversion and stepless speed regulation of the main motor of the fracturing pump group by adjusting the frequency converter, thereby automatically controlling the fracturing process.

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