A method for the exploration and detection of shallow underground natural hydrogen
By drilling a channel with a small drill bit and filling it with soil, combined with the design of sampling tubes and support rods, the problem of accuracy in detecting shallow underground natural hydrogen gas was solved, achieving efficient underground gas sampling and detection.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- GENERAL PROSPECTING INSTITUTE OF CHINA NATIONAL ADMINISTRATION OF COAL GEOLOGY
- Filing Date
- 2026-03-12
- Publication Date
- 2026-06-30
AI Technical Summary
Existing exploration technologies are insufficient to accurately detect natural hydrogen at depths of 3-20 meters underground. Traditional sampling methods cannot effectively prevent gas mixing, resulting in low detection accuracy.
A small drill bit is used to drill and form a channel. The soil drilled out by the drill bit is used to fill the hole to prevent gas diffusion. The sampling tube and support rod are used to ensure that the sampling tube is completely inserted into the ground. The micro thermal conductivity detector and laser spectroscopy analyzer are used for detection.
It enables highly accurate sampling and detection of natural hydrogen in shallow underground layers, avoids gas mixing, and improves the reliability of detection results.
Abstract
Description
Technical Field
[0001] This invention belongs to the field of underground natural hydrogen detection technology, specifically relating to a method for the exploration and detection of shallow underground natural hydrogen. Background Technology
[0002] The natural hydrogen content in underground strata is a crucial aspect of geological exploration, guiding the identification of anomalies and assessing resource potential. Current exploration techniques involve sampling surface soil, drilling gas, and underground seepage gases before sending them to laboratories for analysis. However, hydrogen's small molecular weight, high diffusivity, and chemical reactivity pose challenges to traditional gas sampling and analysis techniques. Furthermore, current technologies primarily target surface or deep underground sampling. Surface sampling (within 1 meter below the ground) can be done directly, while deep underground sampling (beyond 30 meters) involves drilling and lowering sampling equipment. However, sampling gases from strata at depths of 3-20 meters currently lacks effective methods. Direct sampling equipment cannot reach this depth, and drilling methods, due to their shallow depth, easily cause gas mixing with surface gases, severely impacting detection accuracy. Summary of the Invention
[0003] To address the above problems, this invention provides a method for exploring and detecting shallow underground natural hydrogen, comprising:
[0004] S1: Connect the drill bit to the hollow drill rod and drill downwards from the ground surface. When the drill bit reaches the first underground depth, fill the drill hole with the original soil that was drilled to prevent the gas that has escaped from underground from spreading to the ground along the drill hole.
[0005] S2: When the drill bit reaches the second depth underground, stop drilling. The sampling tube is hollow. Insert the sampling tube into the drill rod and extend it into the ground along the drill rod.
[0006] S3: Insert the support rod into the sampling tube and extend it into the ground along the sampling tube until the bottom of the support rod is flush with the bottom of the sampling tube, and then both of them extend out from the bottom of the drill bit.
[0007] S4: Push the sampling tube and support rod down synchronously on the ground so that the bottom of both are inserted into the target sampling position of the stratum at the same time; then pull out the support rod and connect the top of the sampling tube in parallel to the first gas storage chamber and the detection unit, which are used to store gas samples and monitor gas samples in real time, respectively.
[0008] This invention addresses the problem of gas sampling and detection in strata at depths of 3-20 meters, and has developed the above-mentioned method. This depth is too great for methods that involve directly inserting a sampling needle into the ground; the resistance to penetration is too high, and existing devices and sampling needles are incapable of completing the task, often resulting in needle breakage. This depth is also too shallow for conventional underground drilling; wells with a diameter of 1 meter or more typically allow a large amount of underground gas to diffuse out, causing the target gas to mix with surface atmospheric gases, severely impacting the accuracy of detection.
[0009] This invention uses a small drill bit, achieving depths of 3-20 meters without the need for drilling fluid, and brings out loosened soil. As the drill bit descends from the surface, the excavated soil remains on the surface, creating a small space underground to accommodate the drill bit. As the drill bit continues to descend, the excavated soil fills this small space above, and this process repeats. The loosened soil always moves slightly upwards to fill the space originally used to hold the drill bit. Therefore, this invention eliminates the need for drilling fluid to bring out large amounts of underground soil. The goal of this shallow soil drilling is not to create a well, but rather to use the drill bit to guide the drill rod to form a downward channel in the shallow strata, serving as a conduit for subsequent sampling tubes. Therefore, the drill bit only needs to penetrate the ground; it doesn't need to create a large space. In fact, a larger space is less conducive to preserving underground gas and more conducive to surface gas mixing underground. Once the drill bit is underground, the space created is filled in a timely manner to maintain the original state of the underground gas as much as possible, as long as it doesn't hinder the drill bit's continued downward drilling.
[0010] The sampling tube passes through the drill rod and extends out of the drill bit. The sampling tube can be inserted into the ground to a depth of up to 1 meter to reach the final sampling position. However, the sampling tube, which is several meters or tens of meters long, is still easy to break during this process. The present invention inserts a support rod inside the sampling tube to support the sampling tube and ensure that the sampling tube is inserted completely into the last depth before sampling.
[0011] Optionally, in step S1, the outer diameter of the drill bit is 10-20cm, which is larger than the inner diameter of the drill rod. The inner diameter of the drill rod is 7-15cm, which can accommodate the sampling tube. A rubber block is installed inside the bottom of the drill rod, and the outer side of the rubber block is in close contact with the inner wall of the drill rod.
[0012] During installation, first insert a rubber block into the bottom of the drill rod, then connect the drill bit and the drill rod. The bottom of the drill rod has an inwardly protruding positioning ring to hold the bottom of the rubber block in place. Combined with the friction between the side of the rubber block and the inner wall of the drill rod, the rubber block will not fall off.
[0013] Alternatively, the first depth is within 1 meter below the ground surface. During the process of the drill bit drilling down to the first depth from the ground, some of the soil loosened by the drill bit is left on the ground surface, forming a vertical channel. At this time, the channel is not filled, allowing the drill bit to enter the underground smoothly.
[0014] When the drill bit reaches the first depth underground, the channel is filled with the original soil from before the channel until it is level with the ground, but without compaction.
[0015] In practice, when the drill bit first enters the ground, it excavates some soil, forming a vertical underground channel. This channel is not filled immediately, allowing the drill bit to continue its downward journey. The excavated soil is pushed to the surface by the drill bit, without affecting further drilling. This process is repeated until the excavated soil always rises above the drill bit, allowing it to guide the drill rod downwards until it is close to the target sampling location. This method ensures that the underground borehole is always sealed by soil, which helps to block the path of gas diffusion and improves the accuracy of the detection. When the drill bit reaches the first depth, the visible borehole is filled, but not compacted. This allows the drill bit to continue pushing out the excavated soil while sealing the borehole, preventing a large amount of underground gas from escaping and spreading. Because the first depth is relatively shallow, compared to a depth of several meters underground, less gas diffuses outward from this surface opening, and the natural hydrogen content of the underground gas near the surface differs from that of the underground gas.
[0016] Optionally, the sampling tube has a wedge-shaped opening at the bottom for easy insertion into the soil; a filter screen parallel to the wedge-shaped opening is provided at the wedge-shaped opening to prevent a large amount of soil from entering the sampling tube; the sampling tube is segmented to facilitate segmented insertion into the drill rod, and the top of the bottommost segment of the sampling tube is always above the rubber block inside the drill rod.
[0017] Alternatively, the support rod is a slender rod with an outer diameter slightly smaller than the inner diameter of the sampling tube, allowing the support rod to extend into the sampling tube. The bottom end of the support rod has a wedge-shaped plane that is parallel to the wedge-shaped opening at the bottom of the sampling tube. When the sampling tube is inserted into the soil, the bottom end of the support rod abuts against the filter screen and descends together.
[0018] Optionally, the detection unit includes a miniature thermal conductivity detector and a laser spectrometer for detecting the hydrogen concentration and the tritium to hydrogen isotope ratio (δ¹⁸) in the underground gas. 2 H value).
[0019] Optionally, step S2 specifically includes:
[0020] (1) When the drill bit reaches the second depth underground, stop drilling, separate the top of the drill rod from the power unit, and open the top of the drill rod;
[0021] (2) Insert the lowest section of the sampling tube into the drill pipe. When the top of the tube section is lowered to the top of the drill pipe, connect the next section above it. Then continue to lower the sampling tube along the drill pipe. Repeat this process, connecting the next section above the top of each section of the sampling tube.
[0022] (3) When the bottom of the sampling tube reaches the top of the rubber block inside the drill pipe, the lowering of the sampling tube is paused with the rubber block as support.
[0023] Optionally, the second depth is 0.5-0.8 meters from the target sampling location.
[0024] Optionally, step S3 specifically includes:
[0025] (4) When step S2 ends, the top of the sampling tube is above the top of the drill pipe; the lowest segment of the support rod is inserted into the sampling tube, and when the top of the segment is lowered to the top of the sampling tube, the next segment above it is connected, and then the support rod is lowered along the sampling tube; this is repeated, and the next segment above is connected to the top of each segment of the support rod.
[0026] (5) When the bottom of the support rod contacts the filter screen, the bottom of the support rod is flush with the bottom of the sampling tube. At this time, pressure is applied to the top of the sampling tube, which presses the bottom of the sampling tube to pierce the rubber block and extend the drill bit.
[0027] Optionally, step S4 specifically includes:
[0028] (6) The force-applying device presses down on the top of the sampling tube and the support rod, so that the two descend synchronously and insert into the soil layer below the drill bit until the bottom of the sampling tube reaches the target sampling position; then, the force-applying device is removed and the support rod is removed from the top of the sampling tube in sections.
[0029] (7) Connect the top of the sampling tube to a nitrogen cylinder and a discharge pipe in parallel with an air pump to fill the sampling tube with nitrogen, then extract and discharge the nitrogen to purify and replace the original gas in the sampling tube.
[0030] (8) Connect the top of the sampling tube to the first gas storage chamber, the second gas storage chamber and the detection unit in parallel through the air pump. Extract underground gas samples through the sampling tube, fill the first gas storage chamber first, then fill the second gas storage chamber, and finally input the sample gas into the detection cell to detect the concentration of natural hydrogen and its isotopes in the sample gas. Detailed Implementation
[0031] This embodiment provides a method for exploring and detecting shallow underground natural hydrogen, including:
[0032] S1: Connect the drill bit to the hollow drill rod and drill downwards from the ground surface. When the drill bit reaches the first underground depth, fill the drill hole with the original soil that was drilled to prevent the gas that has escaped from underground from spreading to the ground along the drill hole.
[0033] S2: When the drill bit reaches the second depth underground, stop drilling. The sampling tube is hollow. Insert the sampling tube into the drill rod and extend it into the ground along the drill rod.
[0034] S3: Insert the support rod into the sampling tube and extend it into the ground along the sampling tube until the bottom of the support rod is flush with the bottom of the sampling tube, and then both of them extend out from the bottom of the drill bit.
[0035] S4: Push the sampling tube and support rod down synchronously on the ground so that the bottom of both are inserted into the target sampling position of the stratum at the same time; then pull out the support rod and connect the top of the sampling tube in parallel to the first gas storage chamber and the detection unit, which are used to store gas samples and monitor gas samples in real time, respectively.
[0036] In step S1, the outer diameter of the drill bit is 20cm, which is larger than the inner diameter of the drill rod. The inner diameter of the drill rod is 15cm, which can accommodate the sampling tube. A cylindrical rubber block is installed inside the bottom of the drill rod. The outer side of the rubber block is in close contact with the inner wall of the drill rod, which can prevent the soil loosened by the drill bit from entering the drill rod and prevent the gas overflowing from the underground soil from spreading to the ground through the drill rod.
[0037] During installation, first insert a rubber block into the bottom of the drill rod, then connect the drill bit and the drill rod. The bottom of the drill rod has an inwardly protruding positioning ring to hold the bottom of the rubber block in place. Combined with the friction between the side of the rubber block and the inner wall of the drill rod, the rubber block will not fall off.
[0038] The first depth is within 1 meter below the ground surface. During the process of the drill bit drilling down to the first depth, some soil loosened by the drill bit is left on the ground surface, forming a vertical channel. At this time, the channel is not filled, allowing the drill bit to smoothly enter the underground.
[0039] When the drill bit reaches 0.8m underground, the channel is filled with the original soil from before the channel until it is level with the ground, but without compaction.
[0040] The sampling tube has a wedge-shaped opening at the bottom for easy insertion into the soil; a filter screen parallel to the wedge-shaped opening is provided at the wedge-shaped opening to prevent a large amount of soil from entering the sampling tube; the sampling tube is segmented to facilitate segmented insertion into the drill rod, and the top of the bottommost segment of the sampling tube is always above the rubber block inside the drill rod, so that the sampling tube exposed above the drill bit and drill rod is a complete segment, avoiding air leakage from the sampling tube outside the drill bit and drill rod.
[0041] The support rod is a slender rod with an outer diameter slightly smaller than the inner diameter of the sampling tube, allowing it to extend into the tube. The bottom end of the support rod has a wedge-shaped plane parallel to the wedge-shaped opening at the bottom of the sampling tube. When the sampling tube is inserted into the soil, the bottom end of the support rod abuts against the filter screen and descends together, preventing the filter screen from being broken by the soil. Simultaneously, the support rod occupies most of the space inside the sampling tube, preventing fine sand particles from entering. During subsequent air extraction sampling, the sand particles are drawn into the detection unit.
[0042] The support rod is segmented, which facilitates segmented insertion into the sampling tube. Adjacent segments are connected by threads to improve the support strength of the support rod, prevent the support rod from bending, and ensure that there is always a support rod inside the sampling tube to provide support force.
[0043] The detection unit includes a miniature thermal conductivity detector and a laser spectrometer, used to detect the hydrogen concentration and the isotopic ratio (δ¹⁸) of tritium to hydrogen in underground gases. 2 H value).
[0044] Step S2 is as follows:
[0045] (1) When the drill bit reaches the second depth underground, stop drilling, separate the top of the drill rod from the power unit, and open the top of the drill rod;
[0046] (2) Insert the lowest section of the sampling tube into the drill pipe. When the top of the tube section is lowered to the top of the drill pipe, connect the next section above it. Then continue to lower the sampling tube along the drill pipe. Repeat this process, connecting the next section above the top of each section of the sampling tube.
[0047] (3) When the bottom of the sampling tube reaches the top of the rubber block inside the drill pipe, the lowering of the sampling tube is paused with the rubber block as support.
[0048] The second depth is 0.5-0.8 meters from the target sampling location. The drill bit and drill rod form a channel underground, allowing the sampling tube to extend underground.
[0049] In step (2), the two adjacent pipe sections of the sampling tube are connected by threads, and a sealing gasket is set between the threads, which not only makes the sampling tube connection stable, but also improves the airtightness of the sampling tube.
[0050] Step S3 is as follows:
[0051] (4) When step S2 ends, the top of the sampling tube is above the top of the drill pipe; the lowest segment of the support rod is inserted into the sampling tube, and when the top of the segment is lowered to the top of the sampling tube, the next segment above it is connected, and then the support rod is lowered along the sampling tube; this is repeated, and the next segment above is connected to the top of each segment of the support rod.
[0052] (5) When the bottom of the support rod contacts the filter screen, the bottom of the support rod is flush with the bottom of the sampling tube. At this time, pressure is applied to the top of the sampling tube, which presses the bottom of the sampling tube to pierce the rubber block and extend the drill bit.
[0053] Each segment of the support rod is the same length as each segment of the corresponding sampling tube, so that the top of the sampling tube is flush with the top of the support rod in step (5), which facilitates the connection of the force application device and the application of force to the top of the support rod and the sampling tube simultaneously. The force application device is a conventional force application device, such as a cylinder or other driving device.
[0054] In step (5), when the bottom of the support rod contacts the filter screen, the bottom of both the support rod and the sampling tube are at the top of the rubber block, and the tops of both the support rod and the sampling tube are higher than the top of the drill rod. The distance between the top of the sampling tube and the top of the drill rod is greater than the distance between the bottom of the sampling tube and the target sampling position at this time, so that when the sampling tube is inserted into the target sampling position, the top of the sampling tube is still above the drill rod, which facilitates the connection between the first gas storage chamber and the detection unit.
[0055] Step S4 is as follows:
[0056] (6) The force-applying device presses down on the top of the sampling tube and the support rod, so that the two descend synchronously and insert into the soil layer below the drill bit until the bottom of the sampling tube reaches the target sampling position; then, the force-applying device is removed and the support rod is removed from the top of the sampling tube in sections.
[0057] (7) Connect the top of the sampling tube to a nitrogen cylinder and a discharge pipe in parallel with an air pump to fill the sampling tube with nitrogen, then extract and discharge the nitrogen to purify and replace the original gas in the sampling tube.
[0058] (8) Connect the top of the sampling tube to the first gas storage chamber, the second gas storage chamber and the detection unit in parallel through the air pump. Extract underground gas samples through the sampling tube, fill the first gas storage chamber first, then fill the second gas storage chamber, and finally input the sample gas into the detection cell to detect the concentration of natural hydrogen and its isotopes in the sample gas.
[0059] In step (7), the discharge pipe is connected to the detection unit to detect the nitrogen content in the discharged gas. When the nitrogen content is greater than 95%, it means that step (7) is completed, indicating that the original gas in the sampling tube has been almost completely replaced by nitrogen. The pumping speed of the gas pump in this step is 100 ml / min.
[0060] In step (8), both gas storage chambers are pre-vacuumed. The first gas storage chamber is used for long-term storage of sample gas, which can be brought back to the laboratory for retesting. The second gas storage chamber is used for short-term storage of sample gas, which can be retested at the sampling location without having to continuously take samples from underground.
[0061] The detection unit is used to detect the sample gas in real time. The gas pump pumping rate in this step is 500 ml / min.
[0062] This example provides the detailed detection process for the detection unit as follows:
[0063] First, flush the gas path with sample gas at a flow rate of 100 ml / min for 120 seconds, then switch to analysis mode and the gas pump delivers gas into the detection unit at a stable flow rate of 500 ml / min.
[0064] Approximately 90 seconds later, the display showed the results: H2 concentration 1.2% (vol), δ 2 H is -450‰ (vs. SMOW). This value is significantly higher than the atmospheric background and indicates a deep-source mantle or water-rock reaction, suggesting that the sampling location of this target is a strong anomaly, and the GPS system automatically recorded the coordinates.
Claims
1. A method for exploring and detecting shallow underground natural hydrogen, characterized in that, include: S1: Connect the drill bit to the hollow drill rod and drill downwards from the ground surface. When the drill bit reaches the first underground depth, fill the drill hole with the original soil that was drilled to prevent the gas that has escaped from underground from spreading to the ground along the drill hole. S2: When the drill bit reaches the second depth underground, stop drilling. The sampling tube is hollow. Insert the sampling tube into the drill rod and extend it into the ground along the drill rod. S3: Insert the support rod into the sampling tube and extend it into the ground along the sampling tube until the bottom of the support rod is flush with the bottom of the sampling tube, and then both of them extend out from the bottom of the drill bit. S4: Push the sampling tube and support rod down synchronously on the ground so that the bottom of both are inserted into the target sampling position of the stratum at the same time; then pull out the support rod and connect the top of the sampling tube in parallel to the first gas storage chamber and the detection unit, which are used to store gas samples and monitor gas samples in real time, respectively.
2. The exploration and detection method according to claim 1, characterized in that, In step S1, the outer diameter of the drill bit is 10-20cm, which is larger than the inner diameter of the drill rod. The drill rod can accommodate the sampling tube. A rubber block is installed inside the bottom of the drill rod. The outer side of the rubber block is in close contact with the inner wall of the drill rod. This can prevent the soil loosened by the drill bit from entering the drill rod and prevent the gas overflowing from the underground soil from spreading to the ground through the drill rod.
3. The exploration and detection method according to claim 2, characterized in that, The bottom of the drill rod is provided with an inwardly protruding positioning ring, which is used to hold the bottom of the rubber block. Combined with the friction between the side of the rubber block and the inner wall of the drill rod, the rubber block will not fall off. During installation, the rubber block is first inserted into the bottom of the drill rod, and then the drill bit and the drill rod are connected.
4. The exploration and detection method according to claim 3, characterized in that, The first depth is within 1 meter below the ground surface. During the process of the drill bit drilling down to the first depth, some soil loosened by the drill bit is left on the ground surface, forming a vertical channel. At this time, the channel is not filled, allowing the drill bit to smoothly enter the underground. When the drill bit reaches the first depth underground, the channel is filled with the original soil from before the channel until it is level with the ground, but without compaction.
5. The exploration and detection method according to claim 4, characterized in that, The sampling tube has a wedge-shaped opening at the bottom for easy insertion into the soil; a filter screen parallel to the wedge-shaped opening is provided at the wedge-shaped opening to prevent a large amount of soil from entering the sampling tube; the sampling tube is segmented to facilitate segmented insertion into the drill rod, and the top of the bottommost segment of the sampling tube is always above the rubber block inside the drill rod, so that the sampling tube exposed above the drill bit and drill rod is a complete segment, avoiding air leakage from the sampling tube outside the drill bit and drill rod.
6. The exploration and detection method according to claim 5, characterized in that, The support rod is a slender rod with an outer diameter slightly smaller than the inner diameter of the sampling tube, allowing the support rod to extend into the sampling tube. The bottom end of the support rod has a wedge-shaped plane that is parallel to the wedge-shaped opening at the bottom of the sampling tube. When the sampling tube is inserted into the soil, the bottom end of the support rod abuts against the filter screen and goes down together to prevent the filter screen from being broken by the soil. At the same time, the support rod occupies most of the space inside the sampling tube to prevent fine sand particles from entering the sampling tube. During subsequent air extraction sampling, the sand particles are drawn into the detection unit.
7. The exploration and detection method according to claim 1, characterized in that, The detection unit includes a miniature thermal conductivity detector and a laser spectroscopy analyzer, used to detect the hydrogen concentration and the isotopic ratio of tritium to hydrogen in underground gases.
8. The exploration and detection method according to claim 6, characterized in that, Step S2 is as follows: (1) When the drill bit reaches the second underground depth, stop drilling, separate the top of the drill rod from the power device, and leave the top of the drill rod open; the second depth is 0.5-0.8 meters away from the target sampling position; (2) Insert the lowest section of the sampling tube into the drill pipe. When the top of the tube section is lowered to the top of the drill pipe, connect the next section above it. Then continue to lower the sampling tube along the drill pipe. Repeat this process, connecting the next section above the top of each section of the sampling tube. (3) When the bottom of the sampling tube reaches the top of the rubber block inside the drill pipe, the lowering of the sampling tube is paused with the rubber block as support.
9. The exploration and detection method according to claim 8, characterized in that, Step S3 is as follows: (4) When step S2 ends, the top of the sampling tube is above the top of the drill pipe; the lowest segment of the support rod is inserted into the sampling tube, and when the top of the segment is lowered to the top of the sampling tube, the next segment above it is connected, and then the support rod is lowered along the sampling tube; this is repeated, and the next segment above is connected to the top of each segment of the support rod. (5) When the bottom of the support rod contacts the filter screen, the bottom of the support rod is flush with the bottom of the sampling tube. At this time, pressure is applied to the top of the sampling tube, which presses the bottom of the sampling tube to pierce the rubber block and extend the drill bit.
10. The exploration and detection method according to claim 9, characterized in that, Step S4 is as follows: (6) The force-applying device presses down on the top of the sampling tube and the support rod, so that the two descend synchronously and insert into the soil layer below the drill bit until the bottom of the sampling tube reaches the target sampling position; then, the force-applying device is removed and the support rod is removed from the top of the sampling tube in sections. (7) Connect the top of the sampling tube to a nitrogen cylinder and a discharge pipe in parallel with an air pump to fill the sampling tube with nitrogen, then extract and discharge the nitrogen to purify and replace the original gas in the sampling tube. (8) Connect the top of the sampling tube to the first gas storage chamber, the second gas storage chamber and the detection unit in parallel through the air pump. Extract underground gas samples through the sampling tube, fill the first gas storage chamber first, then fill the second gas storage chamber, and finally input the sample gas into the detection cell to detect the concentration of natural hydrogen and its isotopes in the sample gas.