Low-disturbance pressure-maintaining coring device sealing module based on magnetofluid sealing technology
By using magnetohydrodynamic rotary sealing technology combined with a multi-stage pole shoe toothed groove structure, the problem of sealing failure in deep coal seam coring devices was solved, achieving sample purity and extending equipment life, and ensuring the accuracy of gas content measurement.
Patent Information
- Application Number
- CN202511275654.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-08
- Publication Date
- 2025-11-18
AI Technical Summary
Existing pressure-holding coring devices fail to seal under high pressure, leading to sample contamination and reduced equipment lifespan, making it impossible to effectively measure the gas content in deep coal seams.
By employing magnetic fluid rotary sealing technology, a multi-stage pole shoe tooth groove structure is formed through a magnetic fluid sealing cavity and a filter pressure-maintaining module, combined with an emergency protection module, to achieve zero-leakage sealing of the rotating shaft and eliminate mud contamination.
Without altering the main sealing structure, the sealing effect was improved, the risk of mud intrusion was reduced, the equipment lifespan was extended, and the purity of the samples and the accuracy of the measurements were ensured.
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Figure CN120969490A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of deep geological equipment sampling, in particular to a low-disturbance pressure-maintaining coring device sealing module based on magnetic fluid sealing technology. BACKGROUND
[0002] Coal is China's dominant energy source, accounting for more than 56% of total energy consumption in 2020-2021. As the depth of mining extends to 800 meters or more, the ground stress and gas pressure of coal seams increase significantly, leading to increased risk of gas outburst. China's coal seams with a burial depth of 2000 meters or less contain about 36.8 trillion cubic meters of coalbed methane resources, and their efficient development is of strategic significance for optimizing energy structure and ensuring national energy security.
[0003] Gas content is a key parameter for characterizing coalbed methane reservoirs and an indicator for evaluating the safety of coal mining and the development of coalbed methane. During the coal exploration stage, the gas content is usually low. In addition, as the exploration depth increases, the measurement error of gas content increases gradually. In particular, in deep coal seams (depth > 800m), the measurement error of gas content data is large, which cannot effectively guide the safe mining of coal and the development of coalbed methane. Therefore, it is necessary to accurately measure and analyze the gas content of deep coal seams. The technical bottleneck of today's accurate measurement of gas content: depth effect leading to error amplification: for every 100 meters of exploration depth, the measurement error of gas content increases by 8% to 12%, especially in deep coal seams (> 800m), traditional methods cannot guide safe mining; high pressure environment aggravates sealing failure: at 25MPa high pressure, mechanical bearing deformation destroys the sealing integrity, leading to an increase in pressure retention failure rate.
[0004] Limitations of existing technology: current pressure-maintaining coring devices are sealed by mechanical flap structures, which cannot completely prevent coal-containing mud from entering the mechanical structure gaps due to surface tension during drilling, pressure maintenance, and lifting, not only contaminating the sample but also reducing the service life of the equipment.
[0005] To address the above problems, there is an urgent need to develop a device that enhances the sealing effect of the sampling device through magnetic fluid rotary sealing technology without changing the existing main sealing structure, thereby fundamentally preventing mud from entering the sample holding mechanism. SUMMARY
[0006] The purpose of the present application is to design a low-disturbance pressure-maintaining coring device sealing module based on magnetic fluid sealing technology, which adopts an improved thin film feedback restrictor, enhances the sealing effect of the sampling device through magnetic fluid rotary sealing technology, and eliminates the influence of coal-containing mud entering the connecting gap of the mechanical composite device on the sample.
[0007] In order to achieve the above purpose, the application provides a low-disturbance pressure-maintaining coring device sealing module based on magnetic fluid sealing technology, which comprises an outer wall, a filtering pressure-maintaining module, a magnetic fluid sealing cavity and an emergency protection module; the outer wall is provided with a through inner cavity in the axial direction from top to bottom; the filtering pressure-maintaining module, the magnetic fluid sealing cavity and the emergency protection module are arranged in the inner cavity from top to bottom.
[0008] The sealing module is connected in series between the drill pipe and the original mechanical flap type main seal through a flange, and the axial length is ≤160 mm and the outer diameter is ≤120 mm, so that the risk of mud particles entering is reduced and the service life of the main seal is prolonged without changing the structure of the main seal.
[0009] Further, the filtering pressure-maintaining module comprises a magnetic filter screen, an isolation ring and a flushing liquid nozzle; the magnetic filter screen is arranged at the top of the isolation ring, the flushing liquid nozzle is arranged at the center hole position of the isolation ring and is in communication with the flushing liquid channel of the drill pipe; the axis of the flushing liquid nozzle and the center line of the drill pipe form an included angle of 30°±2° and the outlet end is 3-5 mm away from the pole shoe inlet of the magnetic fluid sealing cavity, so as to form an axial positive micro-pressure flow at the pole shoe inlet.
[0010] Further, the magnetic filter screen can be detachably inserted at the top of the isolation ring.
[0011] Further, the magnetic fluid sealing cavity comprises a plurality of pole shoes, permanent magnets and magnetic fluid; the permanent magnets are embedded on the outer wall of the pole shoe, the pole shoe tooth grooves are formed on the inner wall of the pole shoe, and the magnetic fluid is filled in the pole shoe tooth grooves; the radial gap between the pole shoe and the rotating shaft is 0.05-0.08 mm, so that the zero leakage sealing of the rotating shaft is realized under the pressure difference of 0-0.6 MPa.
[0012] Further, the pole shoe tooth groove is 0.8 mm deep and 1.2 mm wide, and the surface contains a plating layer to reduce the friction coefficient.
[0013] Further, the emergency protection module comprises an O-ring and a one-way pressure relief valve with an opening pressure of 1.5 MPa, which is used to drain to the annulus when the pressure in the magnetic fluid cavity abnormally rises; the one-way pressure relief valve is arranged on the O-ring.
[0014] Further, the O-ring automatically compensates for the sealing after the magnetic fluid loses pressure and the compression rate is ≤10%.
[0015] Further, the sealing module continuously operates in the drilling fluid with a solid content of ≤2% for 72 hours without pressure drop.
[0016] The application has the following beneficial effects:
[0017] The application provides a low-disturbance pressure-maintaining coring device sealing module based on magnetic fluid rotary sealing technology. BRIEF DESCRIPTION OF DRAWINGS
[0018] Figure 1 FIG. 1 is a structural schematic diagram of a low-disturbance pressure-maintaining coring device sealing module based on magnetic fluid sealing technology according to the application;
[0019] Figure 2 FIG. 2 is a structural schematic diagram of a filter pressure-maintaining module according to the application;
[0020] Figure 3 FIG. 3 is a structural schematic diagram of a magnetic fluid sealing cavity according to the application;
[0021] Figure 4 FIG. 4 is a structural schematic diagram of an emergency protection module according to the application.
[0022] In the drawings: 1-outer wall, 2-filter pressure-maintaining module, 3-magnetic fluid sealing cavity, 4-emergency protection module, 5-drill rod, 201-magnetic filter screen, 202-isolation ring, 203-flushing liquid injection port, 301-multistage pole shoe, 302-permanent magnet, 303-magnetic fluid, 401-O-ring, 402-one-way pressure relief valve. DETAILED DESCRIPTION
[0023] The technical solutions in the embodiments of the application will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments of the application. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the application.
[0024] It should be noted that the terms "first", "second", and the like in the specification and claims of the application and the above-described drawings are used to distinguish similar objects, and do not necessarily indicate a specific order or sequence. It should be understood that the data thus used can be interchanged under appropriate circumstances, so that the embodiments of the application described herein can be implemented. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device including a series of steps or units does not necessarily limit to those steps or units clearly listed, but can include other steps or units not clearly listed or inherent to the process, method, product or device.
[0025] In the present application, the terms "upper", "lower", "left", "right", "front", "back", "top", "bottom", "inner", "outer", "middle", "vertical", "horizontal", "transverse", "longitudinal" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. These terms are mainly used to better describe the present application and its embodiments, and are not intended to limit the indicated devices, elements or components to have a specific orientation, or to be constructed and operated in a specific orientation.
[0026] In addition, in addition to indicating the orientation or positional relationship, the above-mentioned partial terms may also be used to indicate other meanings, for example, the term "upper" may also be used to indicate a certain dependent relationship or connection relationship in some cases. For those skilled in the art, the specific meaning of these terms in the present application can be understood according to the specific circumstances.
[0027] In addition, the terms "mounting", "setting", "provided with", "connected", "connected", "sleeved" should be broadly understood. For example, it can be fixedly connected, detachably connected, or integrally constructed; it can be mechanically connected or electrically connected; it can be directly connected, or indirectly connected through an intermediate medium, or internal communication between two devices, elements or components. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.
[0028] Referring to Figure 1 The embodiment discloses a low-disturbance pressure-maintaining coring device sealing module based on magnetic fluid sealing technology, which comprises an outer wall 1, a filtering pressure-maintaining module 2, a magnetic fluid sealing cavity 3 and an emergency protection module 4. The outer wall 1 is provided with a through inner cavity in the axial direction from top to bottom. The filtering pressure-maintaining module 2, the magnetic fluid sealing cavity 3 and the emergency protection module 4 are arranged in the inner cavity from top to bottom. The sealing module is connected in series between a drill rod 5 and an original mechanical flap type main seal through a flange, and the axial length is less than or equal to 160 mm and the outer diameter is less than or equal to 120 mm, so that the risk of mud particles invading is reduced and the service life of the main seal is prolonged without changing the structure of the main seal.
[0029] Referring to Figure 2 The filtering pressure-maintaining module 2 comprises a magnetic filter screen 201, an isolation ring 202 and a flushing liquid nozzle 203. The magnetic filter screen 201 is arranged at the top of the isolation ring 202, and the flushing liquid nozzle 203 is arranged at the center hole position of the isolation ring 202 and is in communication with the flushing liquid channel of the drill rod. The axis of the flushing liquid nozzle 203 forms an angle of 30°±2° with the center line of the drill rod, and the outlet end is 3-5 mm away from the pole shoe inlet of the magnetic fluid sealing cavity 3, so as to form an axial positive micro-pressure flow at the pole shoe inlet. The magnetic filter screen and the flushing liquid nozzle jointly form a positive micro-pressure flow at the pole shoe inlet, and real-time block the coal dust-containing mud.
[0030] Further optimize technical scheme, the magnetic filter screen 201 can be detachably inserted in the isolation ring top.
[0031] Reference Figure 3 , the magnetic fluid sealing cavity 3 includes multi-stage pole shoes 301, permanent magnets 302 and magnetic fluids 303;The permanent magnet 302 is embedded on the outer wall of the pole shoe 301, the pole shoe 301 is provided with a pole shoe tooth groove on the inner wall, and the magnetic fluid 303 is filled in the pole shoe tooth groove;The radial gap between the pole shoe 301 and the rotating shaft is 0.05-0.08mm, so that the zero leakage sealing of the rotating shaft is realized under 0-0.6MPa pressure difference. Multi-stage pole shoe-tooth groove structure realizes zero leakage rotary sealing under lower pressure.
[0032] Further optimize technical scheme, the pole shoe tooth groove is 0.8mm deep, the tooth width is 1.2mm, and the surface contains a plating layer to reduce the friction coefficient.
[0033] Reference Figure 4 , the emergency protection module 4 includes an O-shaped gasket 401 and a one-way pressure relief valve 402 with an opening pressure of 1.5MPa, which is used to drain to the annulus when the magnetic fluid cavity abnormally rises in pressure;The one-way pressure relief valve 402 is arranged on the O-shaped gasket 401. The O-shaped gasket is combined with the one-way pressure relief valve, and the abnormal pressure rise is automatically drained.
[0034] Further optimize technical scheme, the O-shaped gasket 401 automatically compensates the sealing after the magnetic fluid loses pressure and the compression rate is ≤10%.
[0035] Further optimize technical scheme, the sealing module continuously operates in 100r / min, 2% solid content drilling fluid for 72h without pressure drop.
[0036] The application provides a low disturbance pressure maintaining coring device sealing module based on magnetic fluid rotary sealing technology, which uses magnetic fluid rotary sealing as a rotary shaft auxiliary sealing module based on the existing pressure maintaining coring device, so that the pollution of coal dust mud to the sample through the connecting gap is eliminated without changing the original main sealing structure, and the overall pressure maintaining reliability is improved.
[0037] The application also includes a running method of a low disturbance pressure maintaining coring device sealing module based on magnetic fluid rotary sealing technology, which specifically includes the following steps:
[0038] S1 assembly: the upper end of the sealing module is connected to the rotating shaft end of the center rod through flange connection (preferably API threaded connection), and the flushing liquid pipeline is connected with the flushing liquid channel in the drill pipe;The lower end of the sealing module is connected to the mechanical flap type sealing structure of the original coring device.
[0039] S2 drilling down: flush liquid nozzle 203 is closed, magnetic fluid 303 is static, O-ring 401 blocks the external mud, and the original mechanical flap seal structure is opened for sampling.
[0040] S3 coring: flush liquid nozzle 203 is opened, magnetic filter screen 201 is real-time filtered, and magnetic fluid 303 rotates with the drill pipe to form a dynamic rotating sealing cavity.
[0041] S4 sealing and pressure maintaining: flush liquid nozzle 203 is closed, magnetic fluid 303 is static, a static seal is formed, O-ring 401 blocks the external mud, and the original mechanical flap seal structure is turned off to keep the sample under the ground stress.
[0042] S5 lifting: flush liquid nozzle 203 is opened, magnetic filter screen 201 is real-time filtered, and magnetic fluid 303 rotates with the drill pipe to form a dynamic rotating sealing cavity to continue to block the annular mud and protect the main sealing ring.
[0043] The above is only the preferred embodiment of the present application, and does not limit the technical scope of the present application. Any slight modification, equivalent change and modification of the above embodiment according to the technical essence of the present application still belongs to the scope of the technical solution of the present application.
Claims
1. A sealing module for a low-disturbance pressure-holding coring device based on magnetohydrodynamic sealing technology, characterized in that, include: The outer wall (1), the filter pressure holding module (2), the magnetic fluid sealing cavity (3) and the emergency protection module (4) are arranged in the inner cavity from top to bottom along the axial direction; the filter pressure holding module (2), the magnetic fluid sealing cavity (3) and the emergency protection module (4) are arranged in the inner cavity from top to bottom; The sealing module is connected in series between the drill pipe and the original mechanical flap-type main seal via a flange, and its axial length is ≤160mm and its outer diameter is ≤120mm, so as to reduce the risk of mud particles intrusion and extend the service life of the main seal without changing the main seal structure.
2. The sealing module of the low-disturbance pressure-holding coring device based on magnetohydrodynamic sealing technology as described in claim 1, characterized in that, The filter and pressure-maintaining module (2) includes a magnetic filter (201), an isolation ring (202), and a flushing fluid nozzle (203). The magnetic filter (201) is located on the top of the isolation ring (202), and the flushing fluid nozzle (203) is located at the center hole of the isolation ring (202) and communicates with the drill pipe flushing fluid channel. The axis of the flushing fluid nozzle (203) forms an angle of 30°±2° with the center line of the drill pipe, and the outlet end is 3-5 mm away from the pole shoe inlet of the magnetic fluid sealing cavity (3) to form an axial positive micro-pressure flow at the pole shoe inlet.
3. The sealing module of a low-disturbance pressure-holding coring device based on magnetohydrodynamic sealing technology as described in claim 2, characterized in that, The magnetic filter (201) is detachably inserted into the top of the isolation ring.
4. A sealing module for a low-disturbance pressure-holding coring device based on magnetohydrodynamic sealing technology as described in claim 2 or 3, characterized in that, The magnetic fluid sealing cavity (3) includes a multi-stage pole shoe (301), a permanent magnet (302), and a magnetic fluid (303); the permanent magnet (302) is embedded on the outer wall of the pole shoe (301), and a pole shoe tooth groove is formed on the inner wall of the pole shoe (301), and the magnetic fluid (303) is filled in the pole shoe tooth groove; the radial gap between the pole shoe (301) and the rotating shaft is 0.05 to 0.08 mm, so that zero leakage sealing of the rotating shaft can be achieved under a pressure difference of 0 to 0.6 MPa.
5. The sealing module of a low-disturbance pressure-holding coring device based on magnetohydrodynamic sealing technology as described in claim 4, characterized in that, The pole shoe has a tooth groove depth of 0.8 mm and a tooth width of 1.2 mm, and its surface is coated to reduce the coefficient of friction.
6. The sealing module of a low-disturbance pressure-holding coring device based on magnetohydrodynamic sealing technology as described in claim 5, characterized in that, The emergency protection module (4) includes an O-ring gasket (401) and a one-way pressure relief valve (402) with an opening pressure of 1.5 MPa, which is used to release pressure to the annulus when the magnetohydrodynamic cavity is abnormally pressurized; the one-way pressure relief valve (402) is disposed on the O-ring gasket (401).
7. The sealing module of a low-disturbance pressure-holding coring device based on magnetohydrodynamic sealing technology as described in claim 6, characterized in that, The O-ring (401) automatically compensates for sealing after the magnetohydrodynamic fluid loses pressure and has a compression ratio of ≤10%.
8. The sealing module of a low-disturbance pressure-holding coring device based on magnetohydrodynamic sealing technology as described in claim 7, characterized in that, The sealing module operated continuously for 72 hours in drilling fluid with a solid content of ≤2% at 100r / min without pressure drop.