Device and method for measuring distribution depth and water pressure of multi-layer confined aquifer

Abstract

The invention belongs to the field of multi-layer confined aquifer exploration in water-power engineering, and particularly relates to a device and method for measuring the distribution depth and water pressure of a multi-layer confined aquifer. The design thought of drilling through one layer, isolating one layer and measuring one layer is adopted, and the positions of the confined water layer top interface and the confined water layer bottom interface are determined according to data measured by a water-bearing layer interface detection sensor and the drainage condition of the outer end of the axial through hole of the drill rod; the measured drilling depth S1 and the measured drilling depth S2 correspond to the depth of the top interface of the confined water layer and the depth of the bottom interface of the confined water layer respectively. When the water pressure P1 and the water pressure P2 of the confined water layer are measured, the drill hole is sealed through the first annular air bag and the second annular air bag in advance, a sealed measurement environment can be provided for the water pressure measurement sensor, and the accuracy of a measurement result is fully ensured. Measurement while drilling of the distribution depth and the water pressure of the multiple confined aquifers can be achieved at the same time, the measurement result is accurate, and great significance is achieved for hydropower station construction.

Description

Technical Field

[0001] The present invention belongs to the field of surveying multi-layer confined water layers in hydropower projects, and more specifically relates to a device for measuring the distribution depth and water pressure of multi-layer confined water layers and a method for measuring the distribution depth and water pressure of multi-layer confined water layers. Background Art

[0002] Some complex strata contain multiple layers of confined water layers. The distribution of confined water layers has a great impact on the dam site selection, reservoir leakage, and dam anti-seepage of hydropower projects.

[0003] The distribution depth and water pressure of multiple layers of confined water layers are the difficulties in groundwater measurement. The existing methods for measuring confined water levels in layers mainly include stop-drilling layered logging method, multi-stage monitoring well method and geophysical method. The stop-drilling layered logging method mainly isolates the target layer by inserting a packer system. When drilling through multiple aquifers, it is necessary to insert casing and inject cement to cement the well. The confined water head is measured by injecting / pumping water into the target layer. The disadvantages of this method are low efficiency, high cost and inability to measure in real time while drilling. The multi-stage monitoring well method is to install multiple independent screens in parallel in the same borehole. Each screen corresponds to an aquifer. The water levels are measured separately by wellhead pressure gauges or downhole sensors. The water levels in multiple layers can be monitored continuously for a long time. The disadvantages of this method are that the distribution of confined water layers must be known and the well construction is complicated. The geophysical method is affected by mineral composition and depth, and its accuracy is limited.

[0004] Existing patent documents on confined water level measurement mainly focus on the measurement of confined water pressure, and there is no method for simultaneously measuring the depth of the confined water layer. The patent documents related to the present invention are as follows: Chinese patent publication CN117738653A (publication date: March 22, 2024) discloses a device and method for measuring water pressure while drilling. The device includes an inlet and outlet for allowing fluid in and out, a flow measurement chamber connected to the inlet and outlet, a sealing and measuring unit for sealing the inlet and outlet and measuring the borehole water pressure, a packer for sealing the borehole, a hydraulic control unit for controlling the packer to seal or release the borehole, a piston, and a thrust ring. This invention allows for real-time measurement of borehole water pressure and fluid flow at different locations by controlling the sealing or release of the borehole, eliminating the unnecessary actions of lifting the drill and replacing drill collars. The main feature of this solution lies in the improvement of the measurement-while-drilling and water pressure measurement device. While the device measures water pressure at the water inflow point and location, it cannot measure the depth and water pressure distribution of multiple confined water layers.

[0005] Chinese patent publication CN106192971A (published on December 7, 2016) discloses a confined water level observation well structure and a multi-layer water level observation method. The water level observation well structure consists of an observation hole and a well pipe placed outside the observation hole. The observation hole is cored into the confined aquifer, and the well pipe is placed in the aquifer above the confined aquifer to observe the water level within the confined aquifer. To observe the water level of the underlying confined aquifer, further drilling is performed within the observation hole to the underlying confined aquifer, and two layers of confined aquifer water level observation well pipes are inserted between the observation hole and the well pipe. This allows the water level elevations and pressure heads of two or more confined water layers to be observed from a single observation well. However, this solution primarily improves the multi-layer water level observation well structure, relying on the known depth distribution of multiple layers of confined water levels to measure the confined water pressure. It cannot directly and simultaneously measure the depth distribution and water pressure of multiple layers. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a device for measuring the distribution depth and water pressure of multiple layers of pressurized water layers, which can simultaneously achieve relatively accurate measurement of the distribution depth and water pressure of multiple layers of pressurized water layers.

[0007] In order to solve the above technical problems, the present invention adopts the following technical solutions: a device for measuring the distribution depth and water pressure of multi-layer confined water layers, comprising a drill bit, a drill rod, an air pump and a ground monitoring system, wherein the drill bit and the drill rod are coaxially fixedly connected together, and an aquifer interface detection sensor is fixedly arranged on the outer circumference of the drill rod at a position adjacent to the drill bit, and the aquifer interface detection sensor includes at least a lateral resistivity sensor and a natural potential sensor; a first annular airbag, a water pressure measurement sensor and a second annular airbag are fixedly arranged on the outer circumference of the drill rod at a side of the aquifer interface detection sensor away from the drill bit, and the first annular airbag, the water pressure measurement sensor and the second annular airbag are arranged in sequence along the axial direction of the drill rod. The first annular airbag is arranged in a circular pattern, and among the three, the first annular airbag is closest to the aquifer interface detection sensor. The first annular airbag, the second annular airbag and the drill pipe are coaxially arranged. The first annular airbag and the second annular airbag are connected to the air pump through the inflation and deflation pipelines respectively. The first annular airbag has a first state in which it can seal the borehole when inflated and a second state in which the borehole is not sealed when deflated. The second annular airbag has a first state in which it can seal the borehole when inflated and a second state in which the borehole is not sealed when deflated. The aquifer interface detection sensor and the water pressure measurement sensor are electrically connected to the ground monitoring system through wires respectively. The drill pipe has an axial through hole, and the axial through hole is connected to the outer surface of the drill bit through a connecting hole.

[0008] The preferred solution is that the drill rod is composed of multiple drill rod units that are coaxially fixedly connected, and a closed connection structure is formed between the side walls of two adjacent drill rod units. The charging and discharging pipelines are connected through pipe joints in the area corresponding to the connection parts of the two adjacent drill rod units, and the wires are connected through line joints in the area corresponding to the connection parts of the two adjacent drill rod units.

[0009] A preferred solution is that a gas pipe laying tube for laying gas charging and discharging pipelines and a wire laying tube for laying wires are fixedly provided on the side wall of the axial through hole of the drill rod.

[0010] A preferred solution is that a plurality of water pressure measuring sensors are arranged in a circular array around the axis of the drill pipe, and the plurality of water pressure measuring sensors located on the same vertical distribution line on the outer peripheral surface of the drill pipe are located on the same independently set measurement line.

[0011] Preferably, the aquifer interface detection sensor further includes a temperature sensor.

[0012] A preferred solution is that a plurality of lateral resistivity sensors are arranged in a circular array around the axis of the drill pipe, and the plurality of lateral resistivity sensors located on the same vertical distribution line on the outer circumferential surface of the drill pipe are located on the same independently set measurement line; a plurality of natural potential sensors are arranged in a circular array around the axis of the drill pipe, and the plurality of natural potential sensors located on the same vertical distribution line on the outer circumferential surface of the drill pipe are located on the same independently set measurement line; a plurality of temperature sensors are arranged in a circular array around the axis of the drill pipe, and the plurality of temperature sensors located on the same vertical distribution line on the outer circumferential surface of the drill pipe are located on the same independently set measurement line.

[0013] Based on the above-mentioned device for measuring the distribution depth and water pressure of multi-layer confined water layers, the present invention also provides a method for measuring the distribution depth and water pressure of multi-layer confined water layers, comprising the following steps: In step 1, the first annular airbag and the second annular airbag are both in the second state beforehand, and the drill rod and the drill bit are drilled vertically as a whole; and the measurement data of the aquifer interface detection sensor is observed in real time using a ground monitoring system; Step 2: When the measurement data of the aquifer interface detection sensor show a decrease in resistivity and a negative anomaly on the SP curve, stop drilling, switch the second annular airbag to the first state, and wait for 10 to 15 minutes. If groundwater continues to flow out from the outer end of the axial through hole of the drill pipe, and the color of the groundwater gradually becomes lighter until it is close to clear water, it is determined that the drill bit has entered the confined water layer. At this time, the drilling depth S1 of the drill bit is recorded, and step 3 is entered; otherwise, steps 1 and 2 are repeated; it is preferred to adopt a solution in which the aquifer interface detection sensor also includes a temperature sensor. At this time, in step 2, the prerequisite for stopping drilling is that the measurement data of the aquifer interface detection sensor show a decrease in resistivity and a negative anomaly on the SP curve, and the temperature measured by the temperature sensor decreases; Step 3: The second annular airbag returns to the second state, and the drill bit continues to drill to the set depth until the water pressure measurement sensor enters the confined water layer. At this time, the first annular airbag and the second annular airbag are both switched to the first state, and the water pressure P1 of the confined water layer is measured using the water pressure measurement sensor; Step 4: The first annular airbag and the second annular airbag are both restored to the second state, the drill bit continues drilling, and the ground monitoring system is used to observe the measurement data of the aquifer interface detection sensor in real time; In step 5, when the measurement data of the aquifer interface detection sensor shows an increase in resistivity and a positive abnormality in the SP curve, drilling is stopped, the first annular airbag is switched to the first state, and the drill is left for 10 to 15 minutes. If the groundwater stabilizes and no longer flows out from the outer end of the axial through hole of the drill pipe, it is determined that the drill bit has left the confined water layer. At this time, the drilling depth S2 of the drill bit is recorded and the process proceeds to step 6. Otherwise, steps 4 and 5 are repeated. When the solution in which the aquifer interface detection sensor also includes a temperature sensor is preferably adopted, the prerequisite for stopping drilling in step 5 is that the measurement data of the aquifer interface detection sensor shows an increase in resistivity and a positive abnormality in the SP curve, and the temperature measured by the temperature sensor increases. Step 6: Switch the second annular airbag to the first state and measure the water pressure P2 of the confined water layer using a water pressure measuring sensor; Step 7: Repeat steps 1 to 6 until the drill bit drills to the designed hole depth.

[0014] The present invention has the following beneficial effects: Adopting an overall design concept of "drilling through one layer, isolating one layer, and measuring one layer," when the drill bit enters the top interface of the confined water layer, the data measured by the aquifer interface detection sensor will show characteristics such as a decrease in resistivity, a negative anomaly in the SP curve, and a decrease in temperature. Furthermore, after the second annular airbag seals the borehole, groundwater will continue to flow out from the outer end of the drill pipe's axial through-hole. The measured drilling depth S1 at this time is the depth of the top interface of the confined water layer. When the drill bit enters the bottom interface of the confined water layer, the data measured by the aquifer interface detection sensor will show characteristics such as an increase in resistivity, a positive anomaly in the SP curve, and an increase in temperature. Furthermore, after the first annular airbag seals the borehole, the groundwater stabilizes and no longer flows out from the outer end of the drill pipe's axial through-hole. The measured drilling depth S2 at this time is the depth of the bottom interface of the confined water layer. When measuring the water pressures P1 and P2 of the confined water layer, pre-sealing the borehole with the first and second annular airbags provides a closed measurement environment for the water pressure measurement sensor, fully ensuring the accuracy of the measurement results. The present invention can simultaneously realize the measurement of the distribution depth and water pressure of multiple layers of confined water layers while drilling, and the measurement results are relatively accurate, which is of great significance to the construction of hydropower stations. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0016] Figure 1 It is a schematic diagram of the overall structure of the present invention; Figure 2 yes Figure 1 AA cross-sectional structural diagram; Figure 3 yes Figure 1 Schematic diagram of the BB cross-section structure.

[0017] The components in the figure are marked as follows: drill bit 1, aquifer interface detection sensor 2, lateral resistivity sensor 21, natural potential sensor 22, temperature sensor 23, first annular airbag 3, water pressure measurement sensor 4, second annular airbag 5, drill pipe 6, drill pipe axial through hole 61, ground monitoring system 7, air pump 8, gas charging and discharging pipeline 9, wire 10, gas pipe laying pipe 11, wire laying pipe 12. DETAILED DESCRIPTION

[0018] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0019] See also Figures 1 to 3 The present invention discloses a device for measuring the distribution depth and water pressure of multi-layer confined water layers, comprising a drill bit 1, a drill rod 6, an air pump 8 and a ground monitoring system 7. The drill bit 1 and the drill rod 6 are coaxially fixedly connected together. The outer peripheral surface of the drill rod 6 is fixedly provided with an aquifer interface detection sensor 2 at a position adjacent to the drill bit 1. The aquifer interface detection sensor 2 includes at least a lateral resistivity sensor 21 and a natural potential sensor 22. In a preferred embodiment, the aquifer interface detection sensor 2 also includes a temperature sensor 23. The outer peripheral surface of the drill rod 6 is fixedly provided with a first annular airbag 3, a water pressure measurement sensor 4 and a second annular airbag 5 on the side of the aquifer interface detection sensor 2 away from the drill bit 1. The first annular airbag 3, the water pressure measurement sensor 4 and the second annular airbag 5 are fixedly provided along the outer peripheral surface of the drill rod 6. The three airbags are arranged in sequence along the axial direction of the drill pipe 6, and the first annular airbag 3 is closest to the aquifer interface detection sensor 2 among the three. The first annular airbag 3, the second annular airbag 5 and the drill pipe 6 are coaxially arranged; the first annular airbag 3 and the second annular airbag 5 are respectively connected to the air pump 8 through the inflation and deflation pipeline 9, the first annular airbag 3 has a first state in which it can seal the borehole when inflated and a second state in which the borehole is not sealed when deflated, and the second annular airbag 5 has a first state in which it can seal the borehole when inflated and a second state in which the borehole is not sealed when deflated; the aquifer interface detection sensor 2 and the water pressure measurement sensor 4 are respectively electrically connected to the ground monitoring system 7 through the wire 10; the drill pipe 6 has an axial through hole 61 of the drill pipe, and the axial through hole 61 of the drill pipe is connected to the outer surface of the drill bit 1 through a connecting hole.

[0020] In order to improve the accuracy of the measurement data, multiple aquifer interface detection sensors 2 and water pressure measurement sensors 4 can be arranged respectively. The specific arrangement is as follows: the water pressure measurement sensors 4 are provided with multiple ones arranged in a circular array around the axis of the drill pipe 6, and the multiple water pressure measurement sensors 4 located on the same vertical distribution line on the outer peripheral surface of the drill pipe 6 are located on the same independently set measurement line; the lateral resistivity sensors 21 are provided with multiple ones arranged in a circular array around the axis of the drill pipe 6, and the multiple lateral resistivity sensors 21 located on the same vertical distribution line on the outer peripheral surface of the drill pipe 6 are located on the same independently set measurement line; the natural potential sensors 22 are provided with multiple ones arranged in a circular array around the axis of the drill pipe 6, and the multiple natural potential sensors 22 located on the same vertical distribution line on the outer peripheral surface of the drill pipe 6 are located on the same independently set measurement line; the temperature sensors 23 are provided with multiple ones arranged in a circular array around the axis of the drill pipe 6, and the multiple temperature sensors 23 located on the same vertical distribution line on the outer peripheral surface of the drill pipe 6 are located on the same independently set measurement line. This is equivalent to evenly spaced sensor strips along the circumference of drill pipe 6. Each sensor strip has multiple sensors of corresponding models spaced along the axis of drill pipe 6. Taking the aquifer interface detection sensor 2 as an example, in the preferred embodiment shown in the accompanying drawings, two symmetrically arranged lateral resistivity sensor strips, two symmetrically arranged spontaneous potential sensor strips, and two symmetrically arranged temperature sensor strips are arranged circumferentially, totaling six sensor strips. Adjacent sensor strips are evenly spaced (i.e., the corresponding central angle spacing between them is 60°). Lateral resistivity sensor 21 is an Rt sensor, and spontaneous potential sensor 22 is an SP sensor. In specific implementations, lateral resistivity sensor 21 and spontaneous potential sensor 22 are the primary measurement tools, while temperature sensor 23 is primarily used for auxiliary verification. Lateral resistivity sensor 21 utilizes a "focused electrode array + four-electrode method + mud correction" approach to detect within a radial range of 1 to 2 meters. The spontaneous potential sensor 22 suppresses drilling fluid interference through intrusion correction and salinity calibration, effectively ensuring the accuracy of measurement results. The water pressure sensor 4 is primarily used to measure the stable pressure of the pressurized water. A variety of high-precision water pressure sensors that meet the design requirements can be selected. The above structural design not only prevents a single measurement line failure from causing problems for the entire line during measurement, but also improves measurement accuracy by simultaneously measuring multiple measurement lines and then evaluating all the data.

[0021] The first and second annular airbags 3 and 5 are typically pressure-resistant rubber bladders. Once inflated, they seal the corresponding drilled section and isolate the aquifer interface. This invention is primarily used for low-pressure (0.1 MPa to 1.0 MPa) and medium-pressure (1.0 MPa to 10.0 MPa) confined aquifers. When the pressure in a confined aquifer is excessive, the weight of the drilling rig makes it difficult to balance the water pressure. The second annular airbag 5 is primarily used to isolate the hydrostatic pressure of the drilling fluid and any interference with the water pressure of the remaining confined aquifer above. The first annular airbag 3 is primarily used to seal the reverse circulation channel, preventing measurement errors caused by the continuous discharge of the measured confined aquifer to the surface.

[0022] To facilitate drilling, the drill rod 6 can generally be composed of multiple drill rod units that are coaxially fixedly connected. A closed connection structure is formed between the side walls of two adjacent drill rod units. Accordingly, the gas charging and discharging pipelines 9 are connected by pipe joints in the area corresponding to the connection parts of the two adjacent drill rod units, and the conductors 10 are connected by line joints in the area corresponding to the connection parts of the two adjacent drill rod units. It is understandable that the specific connection structure involved in the closed connection between the side walls of two adjacent drill rod units can be implemented using the common knowledge of those skilled in the art; for example, the two drill rod units can be connected and fixed using a fixing ring in conjunction with a bolt connection assembly, and a sealing ring can be provided at the joint to ensure the sealing effect. The use of the inflation and deflation lines 9 to inflate and deflate the airbags can also be accomplished using common knowledge known to those skilled in the art. For example, the inflation and deflation lines 9 can share a common air pipe, with an inflation and deflation connector provided at the surface. The inflation and deflation connector can take the form of a nozzle (for details, see the inflation and deflation methods for items such as footballs and basketballs). In other alternative embodiments, the inflation and deflation connector can also take the form of a three-way valve, with one interface for connecting to the corresponding airbag, one interface for connecting to the air pump 8, and another interface for connecting to an openable and closable exhaust port. Of course, in other alternative embodiments, the inflation and deflation lines 9 can also be provided with independent intake and exhaust pipes, each with an openable and closable shut-off valve provided on the intake and exhaust pipes, with the intake pipe being used to connect to the air pump 8.

[0023] The gas charging and discharging pipeline 9 and the wire 10 can generally be laid and connected through the axial through hole 61 of the drill pipe. The gas charging and discharging pipeline 9 can generally adopt a hose structure. In order to better protect the gas charging and discharging pipeline 9 and the wire 10, an air pipe laying tube 11 for laying the gas charging and discharging pipeline 9 and a wire laying tube 12 for laying the wire 10 can also be fixedly provided on the side wall of the axial through hole 61 of the drill pipe.

[0024] Based on the above-mentioned device for measuring the distribution depth and water pressure of multi-layer confined water layers, the present invention also provides a method for measuring the distribution depth and water pressure of multi-layer confined water layers, comprising the following steps: In step 1, the first annular airbag 3 and the second annular airbag 5 are both in the second state beforehand, and the drill rod 6 and the drill bit 1 are drilled vertically as a whole; the ground monitoring system 7 is used to observe the measurement data of the aquifer interface detection sensor 2 in real time; Step 2: When the measurement data of the aquifer interface detection sensor 2 shows a decrease in resistivity and a negative anomaly in the SP curve, stop drilling, switch the second annular airbag 5 to the first state, and wait for 10 to 15 minutes. If groundwater continues to flow out from the outer end of the drill pipe axial through hole 61 and the color of the groundwater gradually becomes lighter until it is close to clear water, it is determined that the drill bit 1 has entered the confined water layer. At this time, the drilling depth S1 of the drill bit 1 is recorded and step 3 is entered; otherwise, steps 1 and 2 are repeated; it is preferred to adopt a solution in which the aquifer interface detection sensor 2 also includes a temperature sensor 23. At this time, in this step 2, the prerequisite for stopping drilling is that the measurement data of the aquifer interface detection sensor 2 shows a decrease in resistivity and a negative anomaly in the SP curve, and the temperature measured by the temperature sensor 23 decreases; Step 3: The second annular airbag 5 returns to the second state, and the drill bit 1 continues to drill to the set depth (the specific drilling depth can be determined according to the axial distance between the drill bit 1 and the water pressure measuring sensor 4 in the device) until the water pressure measuring sensor 4 enters the confined water layer. At this time, the first annular airbag 3 and the second annular airbag 5 are both switched to the first state, and the water pressure P1 of the confined water layer is measured by the water pressure measuring sensor 4; Step 4: The first annular airbag 3 and the second annular airbag 5 are both restored to the second state, the drill bit 1 continues drilling, and the ground monitoring system 7 is used to observe the measurement data of the aquifer interface detection sensor 2 in real time; In step 5, when the measurement data of the aquifer interface detection sensor 2 shows an increase in resistivity and a positive anomaly in the SP curve, drilling is stopped, the first annular airbag 3 is switched to the first state, and the process is left for 10 to 15 minutes. If the groundwater stabilizes and no longer flows out from the outer end of the drill pipe axial through hole 61, it is determined that the drill bit 1 has left the confined water layer. At this time, the drilling depth S2 of the drill bit 1 is recorded, and the process proceeds to step 6. Otherwise, steps 4 and 5 are repeated. When the solution in which the aquifer interface detection sensor 2 also includes a temperature sensor 23 is preferably adopted, the prerequisite for stopping drilling in step 5 is that the measurement data of the aquifer interface detection sensor 2 shows a decrease in resistivity and a negative anomaly in the SP curve, and the temperature measured by the temperature sensor 23 decreases. Step 6: Switch the second annular airbag 5 to the first state, and use the water pressure measuring sensor 4 to measure the water pressure P2 of the confined water layer; Step 7: Repeat steps 1 to 6 until the drill bit 1 drills to the designed hole depth.

[0025] A "negative SP curve anomaly" refers to a negative deviation of the SP (Self-Potential) curve relative to the baseline in spontaneous potential logging; a "positive SP curve anomaly" refers to a positive deviation of the SP (Self-Potential) curve relative to the baseline in spontaneous potential logging. It is understood that the deviation magnitudes corresponding to "negative SP curve anomalies" and "positive SP curve anomalies" can be reasonably determined by those skilled in the art based on actual operating conditions. Similarly, those skilled in the art can reasonably determine the resistivity control thresholds corresponding to the "resistivity decrease" and "resistivity increase" mentioned above based on actual operating conditions, as well as the temperature control thresholds corresponding to the "temperature decrease" and "temperature increase" described above.

[0026] The overall design concept of the present invention is "drill through one layer, isolate one layer, and measure one layer." When the drill bit 1 penetrates the top interface of the confined water layer, the data measured by the aquifer interface detection sensor 2 will show characteristics such as a decrease in resistivity, a negative anomaly on the SP curve, and a decrease in temperature. Furthermore, after the second annular airbag 5 seals the borehole, groundwater will continue to flow out from the outer end of the drill pipe axial through-hole 61. The measured drilling depth S1 at this time is the depth of the top interface of the confined water layer. When the drill bit 1 penetrates the bottom interface of the confined water layer, the data measured by the aquifer interface detection sensor 2 will show an increase in resistivity, a positive anomaly on the SP curve, and an increase in temperature. Furthermore, after the first annular airbag 3 seals the borehole, the groundwater stabilizes and no longer flows out from the outer end of the drill pipe axial through-hole 61. The measured drilling depth S2 at this time is the depth of the bottom interface of the confined water layer. When measuring the water pressures P1 and P2 of the confined water layer, pre-sealing the borehole with the first and second annular airbags 3 and 5 provides a closed measurement environment for the water pressure measurement sensor 4, fully ensuring the accuracy of the measurement results.

[0027] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0028] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A device for measuring the distribution depth and water pressure of a multi-layer confined water layer, comprising a drill bit (1), a drill rod (6) and a ground monitoring system (7), wherein the drill bit (1) and the drill rod (6) are coaxially fixedly connected together, and characterized in that: The invention comprises an air pump (8); an aquifer interface detection sensor (2) is fixedly arranged on the outer peripheral surface of the drill rod (6) at a position adjacent to the drill bit (1); the aquifer interface detection sensor (2) comprises at least a lateral resistivity sensor (21) and a natural potential sensor (22); a first annular airbag (3), a water pressure measurement sensor (4) and a second annular airbag (5) are fixedly arranged on the outer peripheral surface of the drill rod (6) at a side of the aquifer interface detection sensor (2) away from the drill bit (1); the first annular airbag (3), the water pressure measurement sensor (4) and the second annular airbag (5) are arranged in sequence along the axial direction of the drill rod (6); and among the three, the first annular airbag (3) is closest to the aquifer interface detection sensor (2), the first annular airbag (5) is closest to the aquifer interface detection sensor (2), and the second annular airbag (5) is fixedly arranged on the outer peripheral surface of the drill rod (6) at a side of the aquifer interface detection sensor (2) away from the drill bit (1). (3), the second annular airbag (5) and the drill rod (6) are coaxially arranged; the first annular airbag (3) and the second annular airbag (5) are respectively connected to the air pump (8) through the inflation and deflation pipelines (9); the first annular airbag (3) has a first state in which the borehole can be sealed when inflated and a second state in which the borehole is not sealed when deflated; the second annular airbag (5) has a first state in which the borehole can be sealed when inflated and a second state in which the borehole is not sealed when deflated; the aquifer interface detection sensor (2) and the water pressure measurement sensor (4) are respectively electrically connected to the ground monitoring system (7) through the wire (10); the drill rod (6) has an axial through hole (61) of the drill rod, and the axial through hole (61) of the drill rod is connected to the outer surface of the drill bit (1) through the connecting hole.

2. The device for measuring the distribution depth and water pressure of multiple confined water layers according to claim 1, characterized in that: The drill rod (6) is composed of a plurality of drill rod units that are coaxially fixedly connected, and a closed connection structure is formed between the side walls of two adjacent drill rod units. The gas charging and discharging pipelines (9) are connected through a pipe joint in the area corresponding to the connection part of the two adjacent drill rod units, and the conductors (10) are connected through a line joint in the area corresponding to the connection part of the two adjacent drill rod units.

3. The device for measuring the distribution depth and water pressure of multiple confined water layers according to claim 1, characterized in that: A gas pipe laying pipe (11) for laying a gas charging and discharging pipeline (9) and a wire laying pipe (12) for laying a wire (10) are fixedly provided on the side wall of the drill rod axial through hole (61).

4. The device for measuring the distribution depth and water pressure of multiple confined water layers according to claim 1, characterized in that: The water pressure measuring sensors (4) are provided with a plurality of water pressure measuring sensors (4) arranged in a ring array around the axis of the drill rod (6), and the plurality of water pressure measuring sensors (4) located on the same vertical distribution line on the outer peripheral surface of the drill rod (6) are located on the same independently provided measurement line.

5. The device for measuring the distribution depth and water pressure of multiple confined water layers according to any one of claims 1 to 4, characterized in that: The aquifer interface detection sensor (2) further comprises a temperature sensor (23).

6. The device for measuring the distribution depth and water pressure of multiple confined water layers according to claim 5, characterized in that: The lateral resistivity sensors (21) are provided with a plurality of lateral resistivity sensors (21) arranged in a ring array around the axis of the drill rod (6), and the plurality of lateral resistivity sensors (21) located on the same vertical distribution line on the outer peripheral surface of the drill rod (6) are located on the same independently set measurement line; the natural potential sensors (22) are provided with a plurality of lateral resistivity sensors (21) arranged in a ring array around the axis of the drill rod (6), and the plurality of natural potential sensors (22) located on the same vertical distribution line on the outer peripheral surface of the drill rod (6) are located on the same independently set measurement line; and the temperature sensors (23) are provided with a plurality of lateral resistivity sensors (21) arranged in a ring array around the axis of the drill rod (6), and the plurality of temperature sensors (23) located on the same vertical distribution line on the outer peripheral surface of the drill rod (6) are located on the same independently set measurement line.

7. A method for measuring the distribution depth and water pressure of multiple confined water layers, characterized in that: The device for measuring the distribution depth and water pressure of multiple confined water layers according to any one of claims 1 to 4 is used, and comprises the following steps: In step 1, the first annular airbag (3) and the second annular airbag (5) are both in the second state in advance, and the drill rod (6) and the drill bit (1) are drilled vertically as a whole; and the measurement data of the aquifer interface detection sensor (2) is observed in real time using the ground monitoring system (7); Step 2: When the measurement data of the aquifer interface detection sensor (2) shows a decrease in resistivity and a negative anomaly in the SP curve, stop drilling, switch the second annular airbag (5) to the first state, and wait for 10 to 15 minutes. If groundwater continues to flow out from the outer end of the drill pipe axial through hole (61), and the color of the groundwater gradually becomes lighter until it is close to clear water, it is determined that the drill bit (1) has entered the confined water layer. At this time, the drilling depth S1 of the drill bit (1) is recorded and step 3 is entered; otherwise, steps 1 and 2 are repeated. Step 3: the second annular airbag (5) is restored to the second state, and the drill bit (1) continues to drill to the set depth until the water pressure measuring sensor (4) enters the confined water layer. At this time, the first annular airbag (3) and the second annular airbag (5) are both switched to the first state, and the water pressure P1 of the confined water layer is measured using the water pressure measuring sensor (4); Step 4: the first annular airbag (3) and the second annular airbag (5) are both restored to the second state, the drill bit (1) continues drilling, and the ground monitoring system (7) is used to observe the measurement data of the aquifer interface detection sensor (2) in real time; Step 5: When the measurement data of the aquifer interface detection sensor (2) shows that the resistivity increases and the SP curve is abnormal, stop drilling, switch the first annular airbag (3) to the first state, and wait for 10 to 15 minutes. If the groundwater stabilizes and no longer flows out from the outer end of the drill pipe axial through hole (61), it is determined that the drill bit (1) has left the confined water layer. At this time, the drilling depth S2 of the drill bit (1) is recorded and the process goes to step 6; otherwise, repeat steps 4 and 5. Step six, switching the second annular airbag (5) to the first state, and measuring the water pressure P2 of the pressure water layer using the water pressure measuring sensor (4); Step 7: Repeat steps 1 to 6 until the drill bit (1) drills to the designed hole depth.

8. The method for measuring the distribution depth and water pressure of multiple confined water layers according to claim 7, characterized in that: The aquifer interface detection sensor (2) used also includes a temperature sensor (23); the prerequisite for stopping drilling in step 2 is that when the measurement data of the aquifer interface detection sensor (2) shows a decrease in resistivity and a negative anomaly in the SP curve, the temperature measured by the temperature sensor (23) decreases; the prerequisite for stopping drilling in step 5 is that when the measurement data of the aquifer interface detection sensor (2) shows an increase in resistivity and a positive anomaly in the SP curve, the temperature measured by the temperature sensor (23) increases.

9. The method for measuring the distribution depth and water pressure of multiple confined water layers according to claim 8, characterized in that: The arrangement of the aquifer interface detection sensor (2) is as follows: a plurality of lateral resistivity sensors (21) are arranged in a ring array around the axis of the drill rod (6), and the plurality of lateral resistivity sensors (21) located on the same vertical distribution line on the outer peripheral surface of the drill rod (6) are located on the same independently set measurement line; a plurality of natural potential sensors (22) are arranged in a ring array around the axis of the drill rod (6), and the plurality of natural potential sensors (22) located on the same vertical distribution line on the outer peripheral surface of the drill rod (6) are located on the same independently set measurement line; a plurality of temperature sensors (23) are arranged in a ring array around the axis of the drill rod (6), and the plurality of temperature sensors (23) located on the same vertical distribution line on the outer peripheral surface of the drill rod (6) are located on the same independently set measurement line.

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