Force-measuring hole packer and roof crack-controlling fracturing method applying force-measuring hole packer

Abstract

The invention discloses a force measurement hole packer and a roof crack control fracturing method applying the force measurement hole packer, and belongs to the technical field of coal mining. The force measurement hole packer comprises an elastic sleeve, and a monitoring device is arranged on the outer side of the elastic sleeve and used for monitoring the vertical stress and the horizontal stress of a drill hole; the separation sleeve is arranged in the elastic sleeve, and a sealed injection molding area is formed between the inner wall of the elastic sleeve and the outer wall of the separation sleeve; the injection pressure pipe is communicated with the sealing injection pressure area, and the injection pressure pipe is used for enabling the elastic sleeve to expand; the fracturing pipe is arranged on the inner side of the separation sleeve; wherein after the vertical stress is larger than the horizontal stress and the vertical stress reaches a peak value and an inflection point appears, the injection pressure pipe injects pressure to the sealed injection pressure area, and the fracturing pipe injects water to fracture the drilled hole. According to the invention, pressure data can be accurately controlled, and fracturing crack controllability is realized.

Description

Technical Field

[0001] This invention belongs to the field of coal mining technology, and more specifically relates to a force-measuring sealing device and a roof control fracturing method using the same. Background Technology

[0002] In existing thick, hard roof mining operations, excessive pressure step distances result in large roof overhang areas, easily leading to severe mine pressure manifestations, excessive surrounding rock deformation, and hydraulic support overload. Traditional techniques for reducing pressure step distances mainly include blasting, conventional hydraulic fracturing, and directional fracturing. Blasting suffers from difficulties in energy control and irregular fracture development; conventional hydraulic fracturing lacks advanced planning, making it impossible to control fracture initiation and propagation directions, and fracturing parameters are set based on experience, resulting in poor effects in reducing pressure step distances; directional fracturing can guarantee the fracture initiation direction, but its propagation direction is mainly controlled by the stress environment, making it impossible to achieve controllable fracture propagation direction. All of these techniques for reducing pressure step distances cannot accurately control pressure data. Because fractures propagate vertically to the minimum principal stress, fracture initiation and propagation are uncontrollable, thus failing to effectively address the series of safety hazards caused by roof overhangs, hindering mining efficiency and coal mine safety.

[0003] Therefore, how to provide a device and fracturing method that can accurately control pressure data and achieve controllable fracturing fractures is a technical problem that needs to be solved by those skilled in the art. Summary of the Invention

[0004] In view of this, the present invention provides a force-measuring sealing device and a method for controlled fracturing of the top plate using the same, which can accurately control pressure data and achieve controllable fracturing cracks.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A force-measuring sealing device, comprising:

[0007] An elastic sleeve is provided with a monitoring device on its outer side, the monitoring device being used to monitor the vertical and horizontal stresses of the borehole;

[0008] A separating sleeve is disposed inside the elastic sleeve, and a sealing injection zone is formed between the inner wall of the elastic sleeve and the outer wall of the separating sleeve;

[0009] The injection tube is connected to the sealed injection area and is used to expand the elastic sleeve;

[0010] A fracturing tube, wherein the fracturing tube is disposed inside the partition sleeve;

[0011] Specifically, when the vertical stress is greater than the horizontal stress, and the vertical stress reaches its peak and then inflection point, the injection pipe injects pressure into the sealed injection zone, and the fracturing pipe injects water to fracture the borehole.

[0012] Optionally, the fracturing pipe has an outlet on its side wall, and there are two elastic sleeves, which are distributed on both sides of the outlet along the axial direction of the fracturing pipe.

[0013] Optionally, the force-measuring sealing device further includes a sealing element, which is sleeved on the outside of the elastic sleeve to seal the gap between the elastic sleeve and the drilled hole.

[0014] Optionally, the monitoring device includes multiple sensor groups that are uniformly distributed along the length of the elastic sleeve, and each sensor group includes multiple sensors that are uniformly distributed along the circumference of the elastic sleeve.

[0015] A method for controlled fracturing of roof slabs, employing the aforementioned force-measuring sealing device, includes:

[0016] During the drilling of the top slab, the force measuring and sealing device is sent to the predetermined fracturing position of the borehole, and the injection pipe is injected with pressure for the first time to couple the monitoring device with the borehole wall.

[0017] The monitoring device tracks vertical and horizontal stress. When the vertical stress is detected to be continuously increasing and eventually exceeding the horizontal stress, and the vertical stress value reaches an inflection point after reaching a peak plateau, the injection tube injects pressure for the second time to cause the elastic sleeve to expand and seal the borehole.

[0018] The fracturing pipe is used to inject water to fracture the cracks, causing the cracks to expand vertically.

[0019] Optionally, after the fracture propagation is completed, the injection pipe is depressurized to allow the elastic sleeve to contract, and the force measuring and sealing device is moved to the next preset fracturing position. The controlled fracturing method is repeated until the fracturing operation at all preset fracturing positions in the borehole is completed.

[0020] The above technical solution includes at least the following technical effects:

[0021] The monitoring device can monitor the vertical and horizontal stresses of the borehole in real time, providing reliable data support for judging the timing of fracturing and ensuring accurate control of the fracturing direction. When the monitoring device detects that the vertical stress is greater than the horizontal stress and reaches the peak and an inflection point, the injection pipe injects pressure into the sealing injection zone to expand the elastic sleeve, which can seal the borehole and create favorable conditions for subsequent water injection fracturing of the borehole by the fracturing pipe, thereby improving the accuracy and efficiency of fracturing operations. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of the structure of a force-measuring sealing device according to an embodiment of the present invention;

[0024] Figure 2 This is a schematic diagram illustrating the principle of a controlled cracking method for roof slabs in an embodiment of the present invention.

[0025] Explanation of reference numerals in the attached figures:

[0026] 1. Elastic sleeve; 2. Monitoring device; 3. Injection pipe; 4. Fracturing pipe; 5. Outlet; 6. Seal; 7. Crack; 8. Vertical stress; 9. Horizontal stress; 10. Drill hole; 11. Top plate. Detailed Implementation

[0027] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] The terms "first," "second," etc., used in the specification and claims of this invention are used to distinguish similar objects and not to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that embodiments of the invention can be implemented in orders other than those illustrated or described herein, and the objects distinguished by "first," "second," etc., are generally of the same class and the number of objects is not limited; for example, a first object can be one or more. Furthermore, in the specification and claims, "and / or" indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0029] The following description, in conjunction with the accompanying drawings, details a force-measuring sealing device and a method for controlled fracturing of the roof using the same, through specific embodiments and application scenarios.

[0030] See appendix Figure 1-2 This invention provides a force-measuring sealing device and a method for controlled fracturing of the top plate using the same.

[0031] A force-measuring sealing device, comprising:

[0032] The elastic sleeve 1 has a monitoring device 2 on its outer side. The monitoring device 2 is used to monitor the vertical stress 8 and horizontal stress 9 of the borehole 10.

[0033] The monitoring device 2 can monitor the vertical stress 8 and horizontal stress 9 of the borehole 10 in real time, providing reliable data support for judging the timing of fracturing and ensuring accurate control of the fracturing direction.

[0034] Optionally, the monitoring device 2 includes a sensor group and a data acquisition module. The sensor group consists of multiple miniature pressure sensors, which are distributed on the outer surface of the elastic sleeve 1 at preset angles and spacings. These sensors can sense the stress changes transmitted from the inner wall of the borehole 10 in real time from different directions. The data acquisition module is connected to the pressure sensor group through high-temperature resistant wires. It can quickly convert the analog signals collected by the sensors into digital signals and perform preliminary filtering and amplification to ensure the accuracy and stability of the stress data.

[0035] A separating sleeve is provided inside the elastic sleeve 1, and a sealing injection zone is formed between the inner wall of the elastic sleeve 1 and the outer wall of the separating sleeve.

[0036] Injection tube 3 is connected to the sealing injection area and is used to expand the elastic sleeve 1.

[0037] The sealing injection zone is connected to the injection pipe 3 through the injection hole at the end of the elastic sleeve 1. When high-pressure liquid or gas is injected into the sealing injection zone, the elastic sleeve 1 will expand radially due to the increase in internal pressure, thereby tightly fitting the borehole wall 10 and effectively sealing the borehole 10 to prevent leakage of pressure medium during fracturing and ensure the smooth progress of fracturing operations.

[0038] Meanwhile, the partition sleeve not only provides stable internal support for the expansion of the elastic sleeve 1, but also restricts and guides the expansion direction and range of the elastic sleeve 1, preventing the elastic sleeve 1 from being damaged due to excessive expansion and extending its service life.

[0039] Fracturing tube 4 is located inside the partition sleeve.

[0040] Optionally, an annular channel is provided between the outer wall of the fracturing tube 4 and the inner wall of the partition sleeve. This channel not only provides stable support for the fracturing tube 4, but also buffers pressure fluctuations during fracturing, preventing damage to the elastic sleeve 1 or the partition sleeve due to excessive local pressure. In addition, the fracturing tube 4 is made of high-strength alloy steel and undergoes special anti-corrosion and anti-fatigue treatment to ensure that it can maintain good performance and structural stability under long-term high-pressure and highly corrosive working environments.

[0041] Among them, after the vertical stress 8 is greater than the horizontal stress 9, and the vertical stress 8 reaches its peak and an inflection point, the injection pipe 3 injects pressure into the sealed injection zone, and the fracturing pipe 4 injects water into the fracturing borehole 10.

[0042] When the monitoring device 2 detects that the vertical stress 8 is greater than the horizontal stress 9 and reaches the peak and an inflection point, the injection pipe 3 injects pressure into the sealing injection zone, causing the elastic sleeve 1 to expand, which can seal the borehole 10, creating favorable conditions for subsequent water injection and fracturing of the borehole 10 by the fracturing pipe 4, and improving the accuracy and efficiency of fracturing operations.

[0043] Optionally, the side wall of the fracturing pipe 4 is provided with an outlet 5, and the number of elastic sleeves 1 is two, with the two elastic sleeves 1 distributed on both sides of the outlet 5 along the axial direction of the fracturing pipe 4.

[0044] When the injection pipe 3 injects pressure into its corresponding sealed injection zone, the two elastic sleeves 1 expand outward simultaneously and fit tightly against the inner wall of the borehole 10, forming a dual-seal structure. This dual-seal design effectively prevents high-pressure fracturing fluid from leaking along the axial direction of the borehole 10 during fracturing, significantly improving sealing reliability. Simultaneously, the area between the two elastic sleeves 1 forms a relatively independent fracturing operation space, allowing the fracturing fluid to act more concentratedly on the target rock formation corresponding to the outlet 5, enhancing the directionality and controllability of the fracturing effect.

[0045] The location of outlet 5 is precisely calculated, and its diameter and number can be adjusted according to different fracturing requirements to adapt to fracturing fluid supply systems with different discharge rates, ensuring that high-pressure fracturing fluid can be injected into the target rock formation at the optimal flow rate and pressure to achieve efficient fracturing.

[0046] Optionally, the force-measuring sealing device also includes a sealing element 6, which is sleeved on the outside of the elastic sleeve 1 to seal the gap between the elastic sleeve 1 and the drill hole 10.

[0047] The seal 6 is made of highly elastic and wear-resistant rubber, and its inner side is tightly bonded to the outer wall of the elastic sleeve 1. When the elastic sleeve 1 expands, the seal 6 will press outward against the inner wall of the drill hole 10, further enhancing the sealing effect.

[0048] Optionally, the monitoring device 2 includes multiple sensor groups that are evenly distributed along the length of the elastic sleeve 1, and each sensor group includes multiple sensors that are evenly distributed along the circumference of the elastic sleeve 1.

[0049] The uniform arrangement of multiple sensor groups along the length of the elastic sleeve 1 enables simultaneous monitoring of the stress state at different depths of the borehole 10, avoiding misjudgments of the overall rock stress field due to data deviations from a single monitoring point. Multiple sensors evenly distributed along the circumference of the elastic sleeve 1 in each sensor group can comprehensively capture stress changes in different circumferential directions of the borehole 10. By comparing and analyzing the monitoring data from sensors in each direction, the directions of maximum and minimum stress values ​​can be accurately identified, providing crucial information for selecting the fracturing direction.

[0050] Optionally, the sensor uses strain gauges arranged in a cross shape, and its measurement range covers the period from initial ground stress to instantaneous impact stress generated during fracturing. It features fast response speed, high measurement accuracy, and good long-term stability.

[0051] In addition, each sensor is connected to an external data acquisition module via cables to ensure the accuracy and reliability of real-time monitoring data, providing comprehensive data support for the scientific judgment of fracturing timing and the dynamic control of the fracturing process.

[0052] The force-measuring borehole sealer of this invention integrates stress monitoring and high-pressure borehole sealing and fracturing functions. It not only significantly reduces economic costs, saving on drilling, equipment transportation, and labor expenses; but also greatly improves operational efficiency, avoiding equipment relocation and waiting time between different processes, achieving seamless integration of monitoring and intervention; furthermore, it reduces personnel exposure time in hazardous areas and the frequency of operations, enhancing downhole safety.

[0053] A method for controlled fracturing of roof slabs, employing the aforementioned force-measuring sealing device, includes:

[0054] Drill hole 10 in the top plate 11, send the force measuring and sealing device to the predetermined fracturing position of the borehole 10, and inject pressure for the first time through the injection pipe 3 to couple the monitoring device 2 with the borehole wall of the borehole 10.

[0055] Fracturing borehole 10 is constructed in the roof 11 of the working face within the mining roadway. Borehole 10 must be strictly extended along the rock strata to ensure it is within the target layer. The force-measuring sealing device is sent to the predetermined depth of borehole 10. The pressure injection pipe 3 injects pressure for the first time at a relatively low pressure of 1-2 MPa to drive the elastic sleeve 1 to expand, thereby coupling the monitoring device 2 on it with the borehole wall of borehole 10, thus establishing the initial geostress field baseline.

[0056] The vertical stress 8 and the horizontal stress 9 are tracked by the monitoring device 2. When the vertical stress 8 is detected to be continuously increasing and eventually exceeding the horizontal stress 9, and the value of the vertical stress 8 reaches an inflection point after reaching a peak plateau, the injection tube 3 injects pressure for the second time to make the elastic sleeve 1 expand and seal the borehole 10.

[0057] As the coal mining face continues to advance, monitoring device 2 collects stress data and tracks the changes in vertical stress 8 and horizontal stress 9 in real time. Through algorithms, it analyzes the rate of change of stress and the deflection of principal stress direction in real time. When it is detected that vertical stress 8 continues to increase and eventually surpasses horizontal stress 9, and the value of vertical stress 8 reaches a peak plateau and then shows an inflection point, that is, begins to decline, it is determined that borehole 10 has entered the "peak zone leading edge" of the advanced support pressure.

[0058] Optionally, by measuring the horizontal stress 9 and vertical stress, and combining the known rock mass elastic parameters elastic modulus E and Poisson's ratio ν, a mechanical inversion model is established to calculate the stress state change and principal stress direction of the surrounding rock of borehole 10 in real time and in situ.

[0059] Once the system confirms that the optimal fracturing time has been reached, a second injection is immediately performed through the injection pipe 3. The injection pipe 3 rapidly injects high-pressure liquid, causing the elastic sleeve 1 to expand further and form a solid seal within the borehole 10.

[0060] Water is injected into the fracturing pipe 4 to fracture the crack 7, so that the crack 7 expands in the vertical direction.

[0061] Since the rock mass is in a state of maximum vertical stress 8 at this time, according to the classical theory of minimum principal stress propagation of crack 7, the hydraulic fracturing crack 7 is naturally controlled to propagate in the vertical direction, thus forming the preset crack surface.

[0062] Optionally, after the fracture 7 has been propagated by hydraulic fracturing, the injection pipe 3 is depressurized to allow the elastic sleeve 1 to contract, and the force measuring and sealing device is moved to the next preset fracturing position. The controlled fracturing method is repeated until the fracturing operation at all preset fracturing positions within the borehole 10 is completed.

[0063] The fracturing is carried out in a "reverse" segmented manner. That is, after the first segment is completed, the pressure injection pipe 3 is depressurized, the force measuring and sealing device is moved back 10 meters, the next segment is sealed, and the fracturing operation is repeated.

[0064] After the fracturing operation is completed, move 10m forward in front of the working face to begin the next stage of fracturing.

[0065] Optionally, after the fracturing operation is completed, the effects of fracturing on weakening the roof 11 and promoting its timely collapse are comprehensively evaluated by observing the intensity of the mining pressure manifestation at the working face, changes in support resistance, and roadway deformation, and comparing them with untreated areas. This forms a complete "monitoring-intervention-verification" technical closed loop.

[0066] This invention provides in-situ, continuous, and real-time monitoring of borehole stress 10, directly capturing the dynamic evolution of the pressure field of the mining advance support. It accurately identifies the optimal mechanical window period when "vertical stress 8 becomes the maximum principal stress and the stress value begins to decline after reaching its peak." Fracturing is performed within this window period, placing the rock mass in a stress state where it is most susceptible to fracture and the direction of fracture propagation is most controllable. By transforming fracturing into a data-driven, precise intervention, this ensures that fracturing operations always occur at the time of highest stress concentration and greatest effect, thereby significantly improving the weakening effect of a single fracturing operation on the roof 11.

[0067] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other modifications under the guidance of the present invention without departing from the spirit and scope of the claims, and all of these modifications are within the protection scope of the present invention.

Claims

1. A force-measuring sealing device, characterized in that, include: An elastic sleeve is provided with a monitoring device on its outer side, the monitoring device being used to monitor the vertical and horizontal stresses of the borehole; A separating sleeve is disposed inside the elastic sleeve, and a sealing injection zone is formed between the inner wall of the elastic sleeve and the outer wall of the separating sleeve; The injection tube is connected to the sealed injection area and is used to expand the elastic sleeve; A fracturing tube, wherein the fracturing tube is disposed inside the partition sleeve; Specifically, when the vertical stress is greater than the horizontal stress, and the vertical stress reaches its peak and then inflection point, the injection pipe injects pressure into the sealed injection zone, and the fracturing pipe injects water to fracture the borehole.

2. The force-measuring sealing device according to claim 1, characterized in that, The fracturing pipe has an outlet on its side wall, and there are two elastic sleeves, which are distributed on both sides of the outlet along the axial direction of the fracturing pipe.

3. The force-measuring sealing device according to claim 1, characterized in that, It also includes a sealing element, which is sleeved on the outside of the elastic sleeve to seal the gap between the elastic sleeve and the drilled hole.

4. A force-measuring sealing device according to claim 1, characterized in that, The monitoring device includes multiple sensor groups, which are evenly distributed along the length of the elastic sleeve, and each sensor group includes multiple sensors evenly distributed along the circumference of the elastic sleeve.

5. A method for controlled cracking of roof slabs, characterized in that, The force-measuring sealing device according to claims 1-4 includes: During the drilling of the top slab, the force measuring and sealing device is sent to the predetermined fracturing position of the borehole, and the injection pipe is injected with pressure for the first time to couple the monitoring device with the borehole wall. The monitoring device tracks vertical and horizontal stress. When the vertical stress is detected to be continuously increasing and eventually exceeding the horizontal stress, and the vertical stress value reaches an inflection point after reaching a peak plateau, the injection tube injects pressure for the second time to cause the elastic sleeve to expand and seal the borehole. The fracturing pipe is used to inject water to fracture the cracks, causing the cracks to expand vertically.

6. The method for controlled fracture cracking of the roof slab according to claim 5, characterized in that, After the fracture propagation is completed, the injection pipe is depressurized to allow the elastic sleeve to contract, and the force measuring and sealing device is moved to the next preset fracturing position. The controlled fracturing method is repeated until the fracturing operation at all preset fracturing positions in the borehole is completed.

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