A deep high ground stress coal seam drilling hole sealing device and method based on adaptive non-newtonian fluid

Abstract

The application discloses a deep high ground stress coal seam drilling hole sealing device and method based on self-adaptive non-Newtonian fluid, and belongs to the technical field of deep mine hole sealing. The device comprises an outer bag, an inner bag, a grouting unit, a back grouting unit, an air injection unit and a viscosity online monitoring and self-adaptive control unit. Portland cement is injected into the outer bag and the inner bag to form two end plugs. A sealing material is injected into a sealing section formed between the outer bag and the inner bag. The viscosity online monitoring and self-adaptive control unit is used to realize real-time control of the slurry, thereby ensuring the injectability of the sealing material in the grouting stage. The application utilizes the synergistic effect of high ground stress, fracture closure, hole wall dislocation and shear thickening response of deep coal and rock, so that the sealing material gradually forms a dense sealing structure after grouting is completed, and the requirements of the deep high ground stress coal and rock hydrogen storage drilling hole on resisting hole wall deformation, resisting hydrogen leakage and long-term sealing stability can be met.

Description

Technical Field

[0001] This invention relates to the field of deep mine sealing technology, specifically to a device and method for sealing boreholes in deep high-stress coal seams based on adaptive non-Newtonian fluids. Background Technology

[0002] With the transformation of the energy structure and the advancement of the "dual carbon" goal, hydrogen energy, as a clean and efficient secondary energy source, is gradually becoming an important component of the future energy system. Utilizing underground abandoned coal mine spaces for hydrogen storage has become a research hotspot in the field of underground energy storage in recent years due to its advantages such as large space volume, low conversion cost, and long storage period. However, in deep abandoned coal mine environments, due to the high ground stress, the coal and rock masses generally exhibit characteristics such as fracture development, complex pore structure, and redistribution of surrounding rock stress, causing serious sealing and stability problems for hydrogen storage boreholes during long-term service. Shear-thickening non-Newtonian fluids possess stress-response characteristics. When they enter the sealing section and are subjected to high ground stress, fracture closure, and borehole wall misalignment, the material changes from a low-viscosity state to a high-viscosity stabilizing state, which can well meet the requirements of hydrogen storage boreholes for fracture filling and resistance to high ground stress deformation, improving sealing and stability. However, the grout state changes over time during the non-Newtonian fluid grouting process, causing its fluidity to continuously change during grouting, posing certain difficulties for grouting.

[0003] This shows that the existing technology needs further improvement. Summary of the Invention

[0004] One of the objectives of this invention is to provide a borehole sealing device for deep high-stress coal seams based on adaptive non-Newtonian fluids. This device enables real-time control of the slurry state, ensuring the injectability of the sealing material during the grouting stage. It allows the sealing material to fully penetrate the surrounding fractures, micro-fractures, and coal-rock interface gaps. Under the influence of deep high stress, fracture closure, borehole wall slippage, and filtration effect, it forms a high-viscosity retardation state and a tight sealing structure, improving the sealing performance and long-term stability of hydrogen storage boreholes in deep high-stress abandoned coal mines.

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

[0006] A borehole sealing device for deep, high-stress coal seams based on adaptive non-Newtonian fluids includes an outer bladder, an inner bladder, a grouting unit, a grout return unit, and a gas injection unit. It also includes an online viscosity monitoring and adaptive control unit, which comprises a slurry storage tank, an online rheometer, a pressure sensor, a flow meter, a diluent storage tank, a thickener storage tank, a diluent metering pump, a thickener metering pump, a slurry delivery pipeline, and a system control console. The online rheometer is installed inside the slurry storage tank to detect the viscosity signal of the slurry in the tank in real time. The diluent storage tank and the thickener storage tank are respectively connected to the slurry storage tank. The slurry storage tank is used to supply slurry to the grouting unit.

[0007] The hole between the outer and inner bladder bags is a sealing section, and silicate cement slurry is injected into the outer and inner bladder bags to form plugs at both ends;

[0008] The sealing material is injected into the sealing section through the slurry storage tank. The sealing material is a nano-silica / polyethylene glycol composite system.

[0009] The pressure sensor is installed on the grouting unit to collect the pressure signal of the sealing material; the flow meter is used to collect the flow signal of the sealing material.

[0010] The system control console determines the grouting status of the sealing material based on the collected viscosity, pressure, and flow signals.

[0011] The aforementioned deep high-stress coal seam borehole sealing device based on adaptive non-Newtonian fluid includes a grouting unit comprising a first grouting pipe, a second grouting pipe, a grouting pipe valve, and a grouting pump. The second grouting pipe is connected to the slurry storage tank and is used to inject sealing material into the sealing section. The first grouting pipe is used to inject silicate cement slurry into the outer and inner bladders.

[0012] The aforementioned deep high-stress coal seam borehole sealing device based on adaptive non-Newtonian fluid includes a slurry return unit comprising a slurry return pipe and a slurry return pipe valve. The slurry return unit is used to discharge air, residual water, and excess sealing material from the sealing section.

[0013] The aforementioned deep high-stress coal seam borehole sealing device based on adaptive non-Newtonian fluid includes a gas injection unit comprising a gas injection pipe that passes through an outer bladder and an inner bladder in sequence and extends into the bottom of the borehole. The pressure sensor is installed on the gas injection pipe. The gas injection pipe is used for hydrogen injection into the coal and rock.

[0014] The aforementioned deep high-stress coal seam drilling and sealing device based on adaptive non-Newtonian fluids includes an online rheometer with an insertion design, which is installed on the side wall of the slurry storage tank.

[0015] The aforementioned deep high-stress coal seam drilling sealing device based on adaptive non-Newtonian fluid uses silicate cement slurry with the following raw material ratio based on 100 kg of cement: 100 kg of ordinary silicate cement, 8 kg of calcium sulfoaluminate micro-expansion agent, 1.53 kg of composite early strength agent, 0.6 kg of polycarboxylate superplasticizer, 0.01 kg of defoamer, and 38 kg of water.

[0016] The aforementioned deep high-stress coal seam borehole sealing device based on adaptive non-Newtonian fluid includes a composite early-strength agent comprising 1.5 kg of sodium sulfate and 0.03 kg of triethanolamine.

[0017] Another objective of this invention is to provide a method for sealing boreholes in deep, high-stress coal seams based on adaptive non-Newtonian fluids, which employs the aforementioned sealing device. The method comprises the following steps:

[0018] a. Drill a hole and observe the fracture aperture around the hole;

[0019] b. Insert the outer bladder, inner bladder, first grouting pipe, second grouting pipe, air injection pipe and return grouting pipe into the borehole, so that the outer bladder and inner bladder are arranged alternately and form a sealing section;

[0020] c. Silicate cement grout is injected into the outer and inner bladders through the first grouting pipe, causing the outer and inner bladders to expand and fit tightly against the borehole wall, forming plugs at both ends.

[0021] d. After the two end plugs to be formed reach the predetermined bearing state, the sealing material is injected into the sealing section through the second grouting pipe, so that the sealing material enters the cracks and interface gaps around the borehole.

[0022] e. Activate the online viscosity monitoring and adaptive control unit. The system control console adjusts the sealing material based on the collected viscosity, pressure, and flow signals.

[0023] f. The air, residual water and excess sealing material in the sealing section are discharged through the grout return unit; the grout return pipe valve and the second grouting pipe are closed so that the sealing material remains in the sealing section to achieve the purpose of sealing.

[0024] In the aforementioned method for sealing boreholes in deep, high-stress coal seams based on adaptive non-Newtonian fluids, the nano-silica / polyethylene glycol composite system is used as the sealing material, in which the nano-silica has a particle size of 10–50 nm and the polyethylene glycol is of type PEG600 or PEG2000.

[0025] Compared with the prior art, the present invention brings the following beneficial technical effects:

[0026] (1) The present invention proposes a deep high-stress coal seam borehole sealing device based on adaptive non-Newtonian fluid. The device can monitor the viscosity, pressure and flow rate changes of the sealing material in real time during the grouting process through the set viscosity online monitoring and adaptive control unit. The viscosity online monitoring and adaptive control unit also includes a diluent storage tank and a thickener storage tank. The diluent or thickener can be automatically added according to the monitoring results to realize the closed-loop control of the viscosity of the sealing material. This avoids pipe blockage, premature thickening and injection difficulties caused by excessively high slurry viscosity, and also avoids insufficient sealing capacity caused by excessively low slurry viscosity.

[0027] (2) This invention utilizes the synergistic effect of high ground stress, fracture closure, borehole wall displacement and shear thickening response in deep coal and rock to enable the sealing material to gradually form a tight seal structure after grouting, which can meet the requirements of deep high ground stress coal and rock hydrogen storage drilling for resistance to borehole wall deformation, resistance to hydrogen leakage and long-term sealing stability. Attached Figure Description

[0028] Figure 1 This is a diagram of the bladder and its internal structure of the deep high-stress coal seam borehole sealing device based on adaptive non-Newtonian fluid.

[0029] Figure 2 This is a schematic diagram of the overall structure of the deep high-stress coal seam drilling and sealing device based on adaptive non-Newtonian fluid of the present invention.

[0030] Figure 3 This is a schematic diagram of the viscosity online monitoring and adaptive control unit of the present invention.

[0031] In the diagram: 1-Outer bladder, 2-One-way valve, 3-Inner bladder, 4-Grouting pump, 5-Return grout pipe valve, 6-First grouting pipe, 7-Second grouting pipe, 8-Return grout pipe, 9-Air injection pipe, 10-Pressure sensor, 11-Grouting tank, 12-Online rheometer, 13-Grouting pipe valve, 14-Diluent metering pump, 15-Diluent tank, 16-Thickener tank, 17-Thickener metering pump, 18-Flow meter, 19-System control console. Detailed Implementation

[0032] This invention proposes a borehole sealing device and method for deep high-stress coal seams based on adaptive non-Newtonian fluids. To make the advantages and technical solutions of this invention clearer and more explicit, the invention will be further described below with reference to specific embodiments.

[0033] In the description of this application, the words "first," "second," etc., are used only to distinguish different objects and do not limit the quantity or order of execution, nor do they imply that they must be different. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion.

[0034] Combination Figure 1 and Figure 2 As shown, the present invention discloses a borehole sealing device for deep high-stress coal seams based on adaptive non-Newtonian fluid, comprising an outer bladder 1, an inner bladder 3, a grouting unit, a grout return unit, a gas injection unit, and a viscosity online monitoring and adaptive control unit.

[0035] like Figure 3 As shown, the viscosity online monitoring and adaptive control unit includes a slurry storage tank 11, an online rheometer 12, a pressure sensor 10, a flow meter 18, a diluent storage tank 15, a thickener storage tank 16, a diluent metering pump 14, a thickener metering pump 17, a slurry delivery pipeline, a grouting pipe valve 13, and a system control console 19.

[0036] As a preferred embodiment of the present invention, the online rheometer 12 is an insertion type, installed on the side wall of the slurry storage tank 11. Its detection probe extends into the slurry storage tank and is located below the slurry surface, used to detect the viscosity of the sealing slurry in the slurry storage tank in real time during the grouting process; it can capture the actual rheological state inside the slurry storage tank, used to detect the viscosity signal of the slurry in the slurry storage tank in real time. The diluent storage tank and the thickener storage tank are respectively connected to the slurry storage tank; when the slurry in the slurry storage tank is too thick, diluent is supplied to it through the diluent storage tank to adjust the slurry to a suitable range; when the slurry in the slurry storage tank is too thin, slurry is supplied to the diluent storage tank through the thickener storage tank to adjust it to a suitable range.

[0037] The borehole between the outer and inner bladders serves as the sealing section, with end plugs formed by injecting silicate cement grout into both bladders. The silicate cement grout, based on 100 kg of cement, has the following raw material ratio: 100 kg ordinary silicate cement, 8 kg calcium sulfoaluminate micro-expansion agent, 1.5 kg sodium sulfate, 0.03 kg triethanolamine, 0.6 kg polycarboxylate superplasticizer, 0.01 kg defoamer, and 38 kg water. This silicate cement grout can be pumped in a liquid state at room temperature and does not crack under drilling pressure, thus solving the technical problems of shrinkage cracking inherent in traditional sealing cement.

[0038] Sealing material is injected into the sealing section through a slurry storage tank. The sealing material is a nano-silica / polyethylene glycol composite system. Preferably, the nano-silica has a particle size of 10-50 nm. The large number of silanol groups on its surface form hydrogen bonds with the hydroxyl groups of polyethylene glycol, forming an organic-inorganic interpenetrating network structure, which improves the overall viscoelasticity and deformation resistance of the material.

[0039] The pressure sensor is installed on the grouting unit, specifically embedded in the air injection pipe 9 and located within the sealing section, to collect the pressure signal of the sealing material; the flow meter is used to collect the flow signal of the sealing material; the system control console judges the grouting status of the sealing material based on the collected viscosity signal, pressure signal and flow signal.

[0040] The above-mentioned deep high-stress coal seam drilling sealing device based on adaptive non-Newtonian fluid includes a grouting unit comprising a first grouting pipe 6, a second grouting pipe 7, a grouting pipe valve, and a grouting pump 4. The second grouting pipe is connected to a slurry storage tank and is used to inject sealing material into the sealing section. The first grouting pipe is used to inject silicate cement slurry into the outer and inner bladders.

[0041] The aforementioned deep high-stress coal seam borehole sealing device based on adaptive non-Newtonian fluid includes a slurry return unit comprising a slurry return pipe 8 and a slurry return pipe valve 5. The slurry return unit is used to discharge air, residual water, and excess sealing material from the sealing section.

[0042] The aforementioned deep high-stress coal seam borehole sealing device based on adaptive non-Newtonian fluid includes an injection unit comprising an injection pipe 9. The injection pipe 9 passes through an outer bladder and an inner bladder sequentially before extending to the bottom of the borehole. A pressure sensor is installed on the injection pipe. The injection pipe passes through an outer bladder 1 and an inner bladder 3 sequentially before extending to the bottom of the borehole. The injection pipe 9 is mainly used for hydrogen injection into the coal and rock. The slurry return pipe is used to discharge air and determine whether the slurry has been completely injected. A one-way valve 2 located inside the inner and outer bladders is installed on the first injection pipe to prevent backflow. An online viscosity monitoring and adaptive control unit is used to monitor and adjust the viscosity of the sealing material in real time during the grouting process.

[0043] The following description, in conjunction with the aforementioned apparatus, further illustrates the present invention's method for sealing boreholes in deep, high-stress coal seams based on adaptive non-Newtonian fluids.

[0044] A borehole sealing method for deep, high-stress coal seams based on adaptive non-Newtonian fluids includes the following steps:

[0045] Step 1: Conduct drilling operations underground in the coal mine according to the actual needs of the site, determine the depth and diameter of the borehole, and observe the crack opening around the borehole after drilling is completed.

[0046] Step 2: Insert the outer bladder 1, inner bladder 3, first grouting pipe 6, second grouting pipe 7, air injection pipe 9, and return grouting pipe 8 into the borehole, so that the outer bladder 1 and inner bladder 3 are arranged alternately to form a sealing section.

[0047] Step 3: Inject silicate cement grout into the outer bag 1 and the inner bag 3 through the first grouting pipe 6, so that the outer bag 1 and the inner bag 3 expand and fit tightly against the borehole wall to form plugs at both ends.

[0048] Step 4: After the plugs at both ends reach the predetermined load-bearing state (the outer and inner bladders are fully expanded and reach the preset pressure value), inject the nano-silica / polyethylene glycol composite sealing material into the sealing section through the second grouting pipe, so that the sealing material enters the cracks and interface gaps around the borehole.

[0049] Step 5: Activate the online viscosity monitoring and adaptive control unit to collect the viscosity and flow signals of the sealing material in the slurry storage tank and grouting pipeline in real time, and adaptively adjust the sealing slurry based on these signals.

[0050] Step 6: Open the return slurry pipe valve to discharge air, residual water and excess slurry from the sealing section. When the return slurry pipe continuously flows out uniform slurry without obvious air bubbles, it is determined that the sealing section is basically full.

[0051] Step 7: Close the return grout pipe valve and the second injection pipe to leave the sealing material inside the sealing section. Under the influence of deep high ground stress, fracture closure and borehole wall misalignment, the sealing material triggers a shear thickening effect, which improves the sealing material's ability to seal fracture deformation and hydrogen leakage channels.

[0052] In summary, this invention can meet the requirements of high sealing performance, high adaptability and controllable grouting in deep, high-stress coal and rock hydrogen storage boreholes during hydrogen injection, hydrogen storage and long-term service, and can be widely used.

[0053] Any parts not mentioned in this invention can be achieved by referring to existing technologies.

[0054] Those skilled in the art should recognize that the above embodiments are merely illustrative of this application and are not intended to limit this application. Any appropriate changes and variations made to the above embodiments within the essential spirit and scope of this application should fall within the scope of protection of the claims of this application.

Claims

1. A borehole sealing device for deep high-stress coal seams based on adaptive non-Newtonian fluids, comprising an outer bladder, an inner bladder, a grouting unit, a grout return unit, and a gas injection unit, characterized in that: It also includes an online viscosity monitoring and adaptive control unit, which comprises a slurry storage tank, an online rheometer, a pressure sensor, a flow meter, a diluent storage tank, a thickener storage tank, a diluent metering pump, a thickener metering pump, a slurry delivery pipeline, and a system control console. The online rheometer is installed inside the slurry storage tank and is used to detect the viscosity signal of the slurry in the slurry storage tank in real time. The diluent storage tank and the thickener storage tank are respectively connected to the slurry storage tank. The slurry storage tank is used to supply slurry to the grouting unit. The hole between the outer and inner bladder bags is a sealing section, and silicate cement slurry is injected into the outer and inner bladder bags to form plugs at both ends; The sealing material is injected into the sealing section through the slurry storage tank. The sealing material is a nano-silica / polyethylene glycol composite system. The pressure sensor is installed on the grouting unit to collect the pressure signal of the sealing material; the flow meter is used to collect the flow signal of the sealing material. The system control console determines the grouting status of the sealing material based on the collected viscosity, pressure, and flow signals.

2. The borehole sealing device for deep high-stress coal seams based on adaptive non-Newtonian fluid as described in claim 1, characterized in that: The grouting unit includes a first grouting pipe, a second grouting pipe, a grouting pipe valve, and a grouting pump. The second grouting pipe is connected to the grout storage tank and is used to inject sealing material into the sealing section. The first grouting pipe is used to inject silicate cement grout into the outer and inner bladders.

3. The borehole sealing device for deep high-stress coal seams based on adaptive non-Newtonian fluid as described in claim 1, characterized in that: The slurry return unit includes a slurry return pipe and a slurry return pipe valve. The slurry return unit is used to discharge air, residual water and excess sealing material from the sealing section.

4. The borehole sealing device for deep high-stress coal seams based on adaptive non-Newtonian fluid as described in claim 1, characterized in that: The gas injection unit includes a gas injection pipe, which passes through an outer bladder and an inner bladder in sequence and extends into the bottom of the borehole. The pressure sensor is installed on the gas injection pipe. The gas injection pipe is used for hydrogen injection into coal and rock.

5. A borehole sealing device for deep high-stress coal seams based on adaptive non-Newtonian fluids according to claim 1, characterized in that: The online rheometer is an insertion type and is installed on the side wall of the slurry storage tank.

6. A borehole sealing device for deep high-stress coal seams based on adaptive non-Newtonian fluids according to claim 1, characterized in that: The raw material ratio of silicate cement slurry is as follows, based on 100 kg of cement: 100 kg of ordinary silicate cement, 8 kg of calcium sulfoaluminate micro-expansion agent, 1.53 kg of composite early strength agent, 0.6 kg of polycarboxylate superplasticizer, 0.01 kg of defoamer, and 38 kg of water.

7. A borehole sealing device for deep high-stress coal seams based on adaptive non-Newtonian fluids according to claim 6, characterized in that: The composite early strength agent includes 1.5 kg of sodium sulfate and 0.03 kg of triethanolamine.

8. A method for borehole sealing in deep, high-stress coal seams based on adaptive non-Newtonian fluids, characterized in that, It employs the sealing device according to any one of claims 1 to 7, and the method comprises the following steps in sequence: a. Drill a hole and observe the fracture aperture around the hole; b. Insert the outer bladder, inner bladder, first grouting pipe, second grouting pipe, air injection pipe and return grouting pipe into the borehole, so that the outer bladder and inner bladder are arranged alternately and form a sealing section; c. Silicate cement grout is injected into the outer and inner bladders through the first grouting pipe, causing the outer and inner bladders to expand and fit tightly against the borehole wall, forming plugs at both ends. d. After the two end plugs to be formed reach the predetermined bearing state, the sealing material is injected into the sealing section through the second grouting pipe, so that the sealing material enters the cracks and interface gaps around the borehole. e. Activate the online viscosity monitoring and adaptive control unit. The system control console adjusts the sealing material based on the collected viscosity, pressure, and flow signals. f. The air, residual water and excess sealing material in the sealing section are discharged through the grout return unit; the grout return pipe valve and the second grouting pipe are closed so that the sealing material remains in the sealing section to achieve the purpose of sealing.

9. A method for sealing boreholes in deep, high-stress coal seams based on adaptive non-Newtonian fluids, as described in claim 8, is characterized in that... In the pore-sealing material of the nano-silica / polyethylene glycol composite system, the particle size of nano-silica is 10-50 nm, and the polyethylene glycol is PEG600 or PEG2000.

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