System for measuring gas permeability effect based on pressure water test leakage amount

Abstract

The utility model discloses a system based on water pressure test leakage amount measurement gas permeability improvement effect belongs to mine safety monitoring technical field. In view of the existing gas permeability improvement effect evaluation method is easy to be interfered with the downhole environment, difficult quantitative characterization coal body fissure development degree's problem, propose a kind of technical scheme directly reflecting permeability improvement effect through fluid leakage behavior. The system includes double-end plugging device, water injection metering device, plugging water injection device, drainage device and drilling water pressure regulating device;Among them, the double-end plugging device uses two inflatable capsules to isolate the target permeability section, the water injection metering device injects water into the section under constant pressure and accurately measures the leakage amount, and the pressure regulating and drainage device ensures stable pressure and safe operation. The system can realize segmented accurate testing, and the leakage amount directly represents the connectivity and permeability of the fissure, significantly improves the objectivity, repeatability and engineering applicability of the permeability improvement effect evaluation, and is suitable for complex working conditions in coal mine.

Description

Technical Field

[0001] This utility model belongs to the field of mine safety monitoring technology, specifically relating to the detection technology of gas permeability enhancement effect in the gas drainage process, and particularly to a system for measuring the gas permeability enhancement effect based on the leakage of water pressure test. Background Technology

[0002] Currently, most coal seams in my country suffer from high gas content and poor permeability. To address the challenges of gas extraction and increase coal seam permeability to promote gas release, commonly used methods include gas-phase blasting, hydraulic fracturing, and other permeability enhancement measures. These alter the physical and mechanical properties of the coal seam, generating numerous fractures. The degree of fracture development directly and quantitatively reflects the effectiveness of gas permeability enhancement technologies. By monitoring and analyzing fracture development, the extent to which permeability enhancement technologies modify the coal seam structure can be determined, thereby assessing the potential for improving gas extraction efficiency.

[0003] Currently, the main methods for evaluating the effectiveness of gas permeability enhancement include direct monitoring of gas parameters and acoustic CT imaging technology. Direct monitoring of gas parameters indirectly infers the degree of fracture development by monitoring parameters such as gas concentration, flow rate, or pressure; while acoustic CT imaging technology images the internal structure by observing the propagation characteristics of sound waves in the coal seam.

[0004] However, these methods are susceptible to complex environmental factors such as downhole ventilation, electromagnetic interference, and temperature and humidity fluctuations, leading to data distortion or blurred imaging boundaries. They cannot effectively and quantitatively measure the degree of fracture development induced by the permeability enhancement measures, making it difficult to objectively assess the permeability enhancement effect. At the same time, existing methods lack structural support for segmented testing of the entire borehole, making it impossible to fully obtain the effect differences of permeability enhancement sections at different depths. Furthermore, the lack of reliable pressure control and safe drainage mechanisms in the operation process results in poor repeatability of test results.

[0005] In evaluating the effectiveness of gas permeability enhancement, the existing technical approach involves using new technologies (acoustic CT imaging, gas parameter sensors) to implement older methods. This involves monitoring changes in gas concentration or imaging results, and then using the correlation between these indicators and the degree of fracture development to evaluate the permeability enhancement effect. Existing technologies focus on the indirect correlation between "gas parameters / imaging results" and the degree of fracture development, neglecting the essential property of fractures as fluid seepage channels—that is, directly characterizing fracture connectivity by injecting fluid into a closed borehole section and measuring its leakage behavior. Correspondingly, this patent application establishes a technical approach that directly characterizes the degree of fracture development through water pressure testing leakage.

[0006] The fundamental reason for the aforementioned defects in existing technologies lies in the fact that they do not structurally construct a mechanical testing system capable of isolating the target permeability enhancement section within the borehole, achieving constant pressure water injection, and accurately measuring leakage water. Neither gas parameter monitoring nor acoustic CT imaging establishes a direct physical link between "fracture—fluid response—measurable signal," resulting in subjective, ambiguous, and unreliable evaluation results.

[0007] Therefore, there is an urgent need for a system that can avoid interference from complex downhole environments, directly and quantitatively measure the degree of fracture development, support segmented detection of the entire borehole, and have reliable pressure control and drainage mechanisms, so as to accurately evaluate the gas permeability enhancement effect. Utility Model Content

[0008] The purpose of this invention is to provide a technical solution that can directly quantify the gas permeability enhancement effect based on the leakage behavior of fluid in coal seam fractures, so as to overcome the shortcomings of the existing technology in evaluating the degree of fracture development due to reliance on gas parameters or imaging signals that are easily affected by the complex underground environment.

[0009] To achieve the above objectives, the system of this utility model for measuring the gas permeability enhancement effect based on water pressure test leakage includes a double-ended sealing device for isolating the target permeability enhancement section in the borehole, a water injection metering device for injecting constant pressure fluid into the target permeability enhancement section and measuring the leakage, a sealing water injection device for injecting water into the double-ended sealing device, a drainage device connected to the water injection metering device for draining water, and a borehole water injection pressure regulating device connected to the water injection metering device for regulating the borehole water injection pressure.

[0010] The dual-end sealing device includes a first expansion capsule and a second expansion capsule spaced apart along the borehole axis. The first and second expansion capsules, together with the surrounding coal seam, form a target permeability enhancement section. A sealing hose and a water injection pipe for water injection test are connected between the first and second expansion capsules. The sealing hose is used to inject water from the first expansion capsule into the second expansion capsule, thereby expanding the second expansion capsule and sealing the rear end of the target permeability enhancement section. The water injection pipe passes through the first expansion capsule and is connected to a water injection metering device. The water injection pipe is provided with multiple water injection holes spaced apart for injecting water into the target permeability enhancement section.

[0011] The sealing and water injection device includes a water tank, which is connected to a water supply pipe and a water pressure pipe. The water supply pipe is equipped with a water supply valve and is connected to an external water source for replenishing water to the water tank. The water pressure pipe is equipped with a hand pump, a water pressure valve, and a sealing pressure gauge. The water pressure pipe is connected to the first expansion capsule.

[0012] The water injection metering device includes an inlet pipe connected to an external high-pressure water source, with the upstream end of the water injection pipe extending out of the first expansion capsule and connected to the downstream end of the inlet pipe; along the direction from upstream to downstream, the water injection pipe is sequentially equipped with an inlet control valve 4, an inlet pressure gauge, an injection flow meter, an inlet control valve, and an injection pressure gauge; the drainage device includes a drain pipe, which is connected to the inlet pipe between the injection control valve and the injection pressure gauge, and a drain valve is provided on the drain pipe.

[0013] The borehole water injection pressure regulating device includes a pressure regulating discharge pipe, which is connected to the water inlet pipe between the water inlet control valve and the water inlet pressure gauge. The pressure regulating discharge pipe is equipped with a regulating valve for adjusting the water injection pressure.

[0014] This utility model has the following advantages: This invention organically integrates double-end sealing, constant pressure water injection, leakage measurement, pressure regulation, and drainage functions to form a downhole permeability enhancement effect evaluation system with a clear structure, controllable operation, and reliable data. The main technical advantages of this invention are as follows: 1. Achieve precise isolation of local segments.

[0015] A double-ended sealing device (such as two expansion capsules) is used to seal both ends of the target permeability enhancement section in the borehole, forming an independent test chamber; this effectively avoids interference from non-target sections above and below or the entire borehole, so that the leakage only reflects the development state of the coal fracture in the tested section; it supports segment-by-segment testing along the borehole depth to obtain a longitudinal distribution profile of the permeability enhancement effect, providing a basis for optimizing permeability enhancement parameters.

[0016] 2. The permeability enhancement effect can be quantitatively evaluated through constant pressure water injection and precise metering.

[0017] The water injection metering device injects water into the sealing section under constant pressure and records the leakage in real time through a flow meter. The leakage directly reflects the permeability of the coal body and the connectivity of the fractures, avoiding indirect inference errors of parameters that are easily disturbed, such as gas concentration and extraction negative pressure. The data is objective and repeatable, supporting horizontal and vertical quantitative comparisons between different measures, different holes, and different sections.

[0018] 3. An integrated borehole water injection pressure regulating device ensures consistent and safe test pressure. The pressure regulating device (such as a drain valve with a pressure gauge) allows the operator to manually adjust and stabilize the water injection pressure at a preset value (such as p2); ensuring that all tests under the same coal seam are conducted under the same hydraulic conditions, meeting the basic control variable requirements of the water pressure test; 4. Equip with a dedicated drainage device to improve operational efficiency and equipment reusability. The drainage device can quickly drain residual water in the borehole and water accumulated in the sealing section after testing; it facilitates continuous multi-section testing, shortens the single-hole testing cycle, reduces the adverse effects of residual water on subsequent testing or borehole use, and enhances field applicability.

[0019] 5. The overall structure is simple and adaptable to complex underground environments. The system mainly consists of mechanical and hydraulic components (hand pump, valve, bladder, flow meter, pressure gauge), without electrical control or complex sensing components; it is suitable for harsh working conditions in coal mines such as no power supply, high humidity, and confined spaces; it has low manufacturing costs, is easy to maintain, and has good engineering promotion value.

[0020] In summary, this utility model innovatively applies the principle of water pressure testing to the field of gas permeability enhancement effect evaluation, overcoming the shortcomings of existing methods (such as gas parameter monitoring and acoustic CT imaging) such as susceptibility to interference, blurred boundaries, and difficulty in quantification. It provides a field testing method with reasonable structure, standardized operation, reliable data, and low cost, significantly improving the evaluation accuracy and engineering guidance capability of gas permeability enhancement technology implementation effect.

[0021] The double-end sealing device has the following technical advantages: 1. Achieve sequential / synchronous expansion of dual capsules, ensuring reliable sealing at both ends. A sealing hose connects the first and second expansion capsules, allowing water injection to be transferred from the first expansion capsule to the second, driving its expansion. This avoids the need for a separate water injection line for the second expansion capsule, simplifying the downhole deployment structure and reducing the number of pipelines within the borehole. It ensures that both capsules work collaboratively under the same water pressure, providing good sealing synchronization and effectively preventing cross-flow leakage caused by incomplete expansion at one end.

[0022] 2. The water injection pipe is set up independently, realizing the functional decoupling of the test section and the sealing system. The water injection pipe passes through the first expansion capsule and is directly connected to the external water injection metering device, which is separated from the water path for capsule expansion; after the capsule is sealed, the water injection test can be started independently without interference.

[0023] 3. Multiple injection holes are installed on the injection pipe to improve the uniformity of water injection and the representativeness of fracture activation. The multiple injection holes are distributed at intervals along the injection pipe, allowing water to seep into the target permeability enhancement section of coal body from different locations simultaneously. This avoids local preferential seepage or pressure concentration caused by single-point water injection, and more comprehensively reflects the water conductivity of the entire fracture network; it also improves the spatial representativeness and repeatability of leakage measurement and reduces evaluation errors caused by deviations in the water injection location.

[0024] 4. Compact structure and high pipeline integration, adaptable to narrow drilling spaces. The plugging hose and water injection pipe coexist between the two capsules, eliminating the need for additional hole enlargement or complex supports; the small overall outer diameter facilitates smooth placement and retrieval in conventional gas drainage boreholes; meeting the engineering requirements of lightweight and simplified underground equipment in coal mines.

[0025] 5. Supports standardized testing procedures to enhance data comparability. The location, number, and distribution of water injection holes are fixed to ensure consistent water injection boundary conditions for each test; combined with constant pressure water injection control, the difference in leakage truly stems from the state of coal fractures, rather than changes in the water injection method, providing a structural basis for quantitative comparison of different boreholes, different sections of the same borehole, and different permeability enhancement measures.

[0026] In summary, the dual-end plugging device, through its functional separation (water injection plugging vs. water injection test), structural integration (dual capsules + dual pipelines), and water injection optimization (multi-pore distribution), solves the technical challenge of simultaneously achieving segmented plugging and uniform water injection in wells. While ensuring sealing reliability, it significantly improves the accuracy, representativeness, and operability of water pressure tests, and is a key structural support for achieving the core objective of this utility model: "quantitative evaluation of permeability enhancement effect based on leakage."

[0027] The sealing and water injection device has the following advantages: 1. Facilitates water tank replenishment and extends continuous operation capability. The water replenishment pipe connects to the downhole water supply system and is equipped with a water replenishment valve, which can quickly replenish water when the water tank is low. It is especially suitable for multi-stage continuous testing or large-scale borehole inspection scenarios, improving on-site operation efficiency, reducing auxiliary time, and enhancing the practicality and continuous working capability of the system engineering.

[0028] 2. The hand pump and dedicated pressure hose are independently set up to ensure precise and controllable sealing pressure. The pressure hose is dedicated to supplying pressure to the expansion capsule, and is equipped with a hand pump as a power source, eliminating the need for an external high-pressure water source or electricity. Operators can finely adjust the injection volume and pressure by manually pressing the pump to adapt to sealing needs under different hole diameters, depths, and surrounding rock conditions. It is particularly suitable for environments in coal mines where there is no power supply and high explosion-proof requirements, ensuring safety and reliability.

[0029] 3. Install a sealing pressure gauge 11 to visualize and standardize the sealing process. The sealing pressure gauge 11 directly monitors the water pressure acting on the capsule, allowing the operator to observe in real time whether the pressure reaches p1 (the effective sealing threshold), avoiding "under-pressure sealing failure" or "over-pressure damaging the capsule" caused by experience-based judgment. The sealing pressure gauge 11 supports the establishment of a unified sealing pressure standard (e.g., p1 = 0.5 MPa), improving consistency and comparability between different tests.

[0030] 4. The pressure valve 20 provides pipeline control, enhancing operational safety and process standardization. The pressure valve 20 is located on the outlet side of the hand pump and is used to start and stop the injection of water into the capsule; after the target sealing pressure is reached, closing the valve can lock the pressure inside the capsule and prevent backflow or pressure leakage.

[0031] 5. The overall structure is modular, which facilitates maintenance and fault isolation.

[0032] The sealing and water injection device (water tank + water supply pipe + water pressure pipe) is functionally separate from the water injection metering device and the pipeline is independent; if the sealing system leaks or malfunctions, it will not affect the accuracy of the metering system, and vice versa; all components (such as hand pump, valve and pressure gauge) are standard parts, which are easy to replace and maintain.

[0033] The plugging water injection device, by introducing a replenishable water tank, an independent manual pressurization circuit, and a dedicated plugging pressure monitoring system, solves practical problems such as limited downhole plugging water sources, uncontrollable pressure, and blind operation. It not only ensures that the double-ended expansion capsule reliably, stably, and in a standardized manner completes the plugging task, but also significantly improves the continuous operation capability, operational safety, and engineering adaptability of the entire system, laying a solid foundation for subsequent high-precision leakage testing.

[0034] The water injection metering device has the following advantages: Pressure gauge 3 is located after water injection control valve 7 and before water injection pipe 16, accurately reflecting the actual water injection pressure acting on the target permeability enhancement section; flow meter 2 is located upstream of the main line, measuring the complete injection volume and is not affected by downstream leakage, making the data more reliable. Dual pressure monitoring enables data self-verification, improving test reliability; inlet pressure gauge 1 monitors the inlet pressure, and water injection pressure gauge 3 monitors the actual borehole pressure; the difference between the two is the pipeline head loss. By comparing the two gauges, it is possible to determine in real time whether the pipeline is blocked or leaking, and problems can be quickly located when data is abnormal, avoiding erroneous data leading to distorted evaluation. Drain pipe 8 is connected between water injection control valve 7 and water injection pressure gauge 3. When drain valve 9 is opened, high-pressure water in the borehole can be quickly discharged, while the upstream inlet pipe 13 maintains pressure. This design allows the sealing device to be moved to the next depth without emptying the entire system after a single-section test, resulting in high section switching efficiency. The water injection metering device, through the design of an external high-pressure water source, a reasonable component sequence, and a dedicated drainage pressure regulating branch, has transformed the system from a "simple manual device" into a "standardized, pressure-stabilized, and highly efficient" engineering testing equipment. It significantly improves the accuracy of water injection pressure control, the reliability of leakage measurement, and the efficiency of on-site operations, and is the key technical support for realizing the quantitative evaluation of the gas permeability enhancement effect of this utility model.

[0035] The borehole water injection pressure regulating device achieves high-precision pressure regulation with a simple structure by setting a manual pressure regulating and discharge branch at the front end of the system. It effectively solves the problem of uncontrollable pressure caused by external high-pressure water source, and significantly improves the stability, accuracy and engineering applicability of water pressure test. It is the key control link to achieve the goal of "quantitative evaluation of permeability enhancement effect based on leakage" of this utility model. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the structure of this utility model. Detailed Implementation

[0037] like Figure 1As shown, the system for measuring the gas permeability enhancement effect based on water pressure test leakage of this utility model includes a double-ended sealing device for isolating the target permeability enhancement section in the borehole, a water injection metering device for injecting constant pressure fluid into the target permeability enhancement section and measuring the leakage, a sealing water injection device for injecting water into the double-ended sealing device, a drainage device connected to the water injection metering device for draining water, and a borehole water injection pressure regulating device connected to the water injection metering device for regulating the borehole water injection pressure.

[0038] The double-ended sealing device includes a first expansion capsule 15 and a second expansion capsule 18 spaced apart along the borehole axis. The first expansion capsule 15 and the second expansion capsule 18, together with the surrounding coal body, form a target permeability enhancement section. A sealing hose 17 and a water injection pipe 16 for water injection test are connected between the first expansion capsule 15 and the second expansion capsule 18. The sealing hose 17 is used to inject water from the first expansion capsule 15 into the second expansion capsule 18, thereby causing the second expansion capsule 18 to expand and seal the rear end of the target permeability enhancement section. The water injection pipe 16 passes through the first expansion capsule 15 and is connected to a water injection metering device. The water injection pipe 16 is provided with multiple water injection holes evenly spaced on it for injecting water into the target permeability enhancement section.

[0039] The sealing and water injection device includes a water tank 19, which is connected to a water supply pipe 10 and a water pressure pipe 12. The water supply pipe 10 is equipped with a water supply valve 22 and is connected to an external water source (such as a well water supply pipe) to supply water to the water tank 19. The water pressure pipe 12 is equipped with a hand pump 21, a water pressure valve 20 and a sealing pressure gauge 11, and is connected to the first expansion capsule 15.

[0040] The water metering device includes an inlet pipe 13 connected to an external high-pressure water source (such as a high-pressure water supply pipe or water pump), and the upstream end of the water injection pipe 16 extends out of the first expansion capsule 15 and is connected to the downstream end of the inlet pipe 13. Along the direction from upstream to downstream, the water injection pipe 16 is sequentially equipped with an inlet control valve 4, an inlet pressure gauge 1, an inlet flow meter 2, an inlet control valve 7, and an inlet pressure gauge 3. The drainage device includes a drain pipe 8, which is connected to the inlet pipe 13 between the inlet control valve 7 and the inlet pressure gauge 3. The drain pipe 8 is equipped with a drain valve 9.

[0041] The borehole water injection pressure regulating device includes a pressure regulating discharge pipe 6, which is connected to the water inlet pipe 13 between the water inlet control valve 4 and the water inlet pressure gauge 1. The pressure regulating discharge pipe 6 is equipped with a regulating valve 5 for regulating the water injection pressure.

[0042] I. System Composition and Parameter Definition.

[0043] This system, which measures the gas permeability enhancement effect based on water pressure test leakage, consists of five main modules: 1. Double-ended sealing device: First expansion capsule 15 and second expansion capsule 18 are connected by sealing hose 17; water injection pipe 16 passes through the first expansion capsule 15, and the pipe wall of water injection pipe 16 is provided with multiple water injection holes; 2. Sealing and water filling device: water tank 19, hand pump 21, water pressure valve 20, sealing pressure gauge 11, specifically used for filling capsules with water; 3. Water metering device: water inlet pipe 13, water inlet control valve 4, water inlet pressure gauge 1, water inlet flow meter 2, water inlet control valve 7, water inlet pressure gauge 3; 4. Drainage device: Drain pipe 8 and drain valve 9, used to drain water accumulated in the test section; 5. Drilling water injection pressure regulating device: pressure regulating and discharge pipe 6 and regulating valve 5, used for fine control of water injection pressure.

[0044] 6. Definition of key parameters: p1: The internal pressure required for the expansion capsule to achieve a reliable hydraulic seal, typically 1.2–1.5 times that of p2 (e.g., if p2 = 0.3 MPa, then p1 ≈ 0.4–0.45 MPa), is monitored by the sealing pressure gauge 11; p2: The constant water injection pressure applied to the target permeability enhancement section during the water pressure test is higher than the formation hydrostatic pressure (approximately 0.01–0.05 MPa) and lower than the coal body hydraulic fracturing pressure (usually <1.0 MPa), with a typical value of 0.2–0.5 MPa, and is monitored and uniformly controlled by the water injection pressure gauge 3.

[0045] II. Phased Workflow

[0046] Phase 1: System assembly and preparation (S100).

[0047] Connect all devices as designed, and fill water tank 19 to about 2 / 3 of its capacity; The upstream of the water inlet pipe 13 is connected to the underground water supply system (or a small pressure stabilizing pump) to ensure that a water source pressure of ≥p2 can be provided; Check that all valves are closed and that the flow meter is set to zero.

[0048] Phase 2: Deployment and capsule sealing (S200).

[0049] Lower the double-ended sealing device to the target permeability enhancement section; close the inlet control valve 4 and the injection control valve 7 to isolate the injection metering circuit; Open the pressure valve 20 and operate the hand pump 21 to inject water into the first expansion capsule 15. The pressure is transmitted to the second expansion capsule 18 through the sealing hose 17. Observe the sealing pressure gauge 11 and continue to pressurize until it is ≥p1 and stabilizes. The pressure valve 20 is closed, and the seal is maintained by the elasticity of the capsule material and the incompressibility of water; the two capsules expand and fit against the hole wall, forming a sealed test chamber between the two capsules.

[0050] Phase 3: Constant pressure water injection test (S300).

[0051] Open the inlet control valve 4 to allow water to enter the main pipeline; slowly adjust the regulating valve 5 to control the discharge flow of the pressure regulating and discharge pipe 6, so that the system pressure gradually increases; Closely observe the inlet pressure gauge 1. When the pressure rises to p2, open the water injection control valve 7. The system water pressure drops. Slowly adjust the regulating valve 5 and observe the water injection pressure gauge 3. When the water injection pressure stabilizes at the preset p2 and the fluctuation is ≤ ±0.02MPa, stop adjusting. High-pressure water is evenly injected into the target permeability enhancement section through the water injection pipe 16 and the multi-hole. Start timing synchronously and record the cumulative flow Q (unit: L) of water injection flow meter 2 within a predetermined time T (e.g., 10 minutes). During the water injection process, the regulating valve 5 can be finely adjusted to maintain the reading of the water injection pressure gauge 3 at p2±0.02MPa.

[0052] Phase 4: Test End and Reset (S400). After time T is reached, first close the water injection control valve 7 to stop water injection into the coal body; then close the water inlet control valve 4 to cut off the main water source; open the drain valve 9 to drain the residual water in the borehole and water injection pipe 16 through the drain pipe 8; after there is no water flow in the drain pipe 8, you can try to open the pressure valve 20 to release the water pressure in the capsule. After the capsule contracts, the system of this invention, which measures the gas permeability enhancement effect based on the leakage of water pressure test, can be moved to the next measuring point in the borehole.

[0053] Phase 5: Full borehole test (S500).

[0054] The area to be tested in the borehole is divided into several target penetration enhancement sections. For each target penetration enhancement section, S200–S400 is repeated and tested section by section. Each time water is injected, the pressure gauge 3 is strictly controlled at the same p2±0.02MPa; Obtain the leakage sequence {Q1,Q2,...,Q} n}

[0055] Phase 6: Benchmarking and Performance Evaluation (S600).

[0056] For adjacent untreated conventional boreholes, perform the exact same test procedure (same p2, same T, same section length). Obtain the baseline leakage rate {Q} 01 Q 02 ,...,Q on}; Calculate the anti-reflection coefficient for each segment: η i =Q i / Q oi ; Average transparency enhancement coefficient across the entire pore: η̄=(Ση i ) / n; η i >1 indicates that the enhancement effect of this segment is effective; the larger the η̄, the more significant the overall enhancement effect.

[0057] III. Summary of Technological Advantages

[0058] 1. Pressure grading and functional decoupling: P1 (blocking) and P2 (testing) are controlled by independent circuits, without interference, ensuring reliable sealing; 2. Constant pressure steady-state test: The pressure of p2 is accurately stabilized by regulating valve 5, and the cumulative leakage is recorded after the steady state is reached. The data is scientific and reliable. 3. Uniform water injection through multiple pores: Improves test representativeness and avoids localized flow deviation; 4. Standardized processes support quantitative comparison: Under the same p2, T, and segment length conditions, the difference in leakage truly reflects the difference in fracture development; 4. Simple structure and adaptable to downhole operation: No electrical control or complex sensors, safe operation, and easy to promote.

[0059] The above embodiments are only used to illustrate and not limit the technical solutions of this utility model. Although the utility model has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the utility model without departing from the spirit and scope of the utility model. Any modifications or partial substitutions should be covered within the scope of the claims of this utility model.

Claims

1. A system for measuring the gas permeability enhancement effect based on water pressure test leakage, characterized in that: It includes a double-ended sealing device for isolating a target permeability enhancement section within a borehole, a water injection metering device for injecting constant-pressure fluid into the target permeability enhancement section and measuring leakage, a sealing water injection device for injecting water into the double-ended sealing device, a drainage device connected to the water injection metering device for draining water, and a borehole water injection pressure regulating device connected to the water injection metering device for regulating the borehole water injection pressure.

2. The system for measuring gas permeability enhancement based on water pressure test leakage as described in claim 1, characterized in that: The dual-end sealing device includes a first expansion capsule and a second expansion capsule spaced apart along the borehole axis. The first and second expansion capsules, together with the surrounding coal seam, form a target permeability enhancement section. A sealing hose and a water injection pipe for water injection test are connected between the first and second expansion capsules. The sealing hose is used to inject water from the first expansion capsule into the second expansion capsule, thereby expanding the second expansion capsule and sealing the rear end of the target permeability enhancement section. The water injection pipe passes through the first expansion capsule and is connected to a water injection metering device. The water injection pipe is provided with multiple water injection holes spaced apart for injecting water into the target permeability enhancement section.

3. The system for measuring gas permeability enhancement based on water pressure test leakage as described in claim 2, characterized in that: The sealing and water injection device includes a water tank, which is connected to a water supply pipe and a water pressure pipe. The water supply pipe is equipped with a water supply valve and is connected to an external water source for replenishing water to the water tank. The water pressure pipe is equipped with a hand pump, a water pressure valve, and a sealing pressure gauge. The water pressure pipe is connected to the first expansion capsule.

4. The system for measuring gas permeability enhancement based on water pressure test leakage as described in claim 3, characterized in that: The water injection metering device includes an inlet pipe connected to an external high-pressure water source, with the upstream end of the water injection pipe extending out of the first expansion capsule and connected to the downstream end of the inlet pipe; along the direction from upstream to downstream, the water injection pipe is sequentially equipped with an inlet control valve, an inlet pressure gauge, an injection flow meter, an injection control valve, and an injection pressure gauge; the drainage device includes a drain pipe, which is connected to the inlet pipe between the injection control valve and the injection pressure gauge, and a drain valve is provided on the drain pipe.

5. The system for measuring gas permeability enhancement based on water pressure test leakage as described in claim 4, characterized in that: The borehole water injection pressure regulating device includes a pressure regulating discharge pipe, which is connected to the water inlet pipe between the water inlet control valve and the water inlet pressure gauge. The pressure regulating discharge pipe is equipped with a regulating valve for adjusting the water injection pressure.

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