Device and method for measuring flow direction and flow velocity in hole

Abstract

The invention discloses a device and a method for measuring the flow direction and the flow velocity in a hole, and belongs to the technical field of water conservancy, hydrogeology and engineering geology. According to the measuring device, a plurality of conductivity probes are arranged on the lower edge of an upper tank base, and an electronic compass is arranged in each conductivity probe and used for measuring the flow direction of underground water in a hole; the bottom of the upper tank body is connected with the lower tank body, and a certain distance is reserved between the upper tank body and the lower tank body; the lower tank top cover is provided with a nozzle, and the lower tank base is provided with a water inlet hole. The technical problems that in the prior art, the flow direction and the flow speed of underground water in a micro-scale range in a single drill hole cannot be measured, and vertical turbulent flow interference of the underground water cannot be avoided in the measuring process are solved.

Description

Technical Field

[0001] The invention belongs to the technical field of water conservancy, hydrogeology and engineering geology, and specifically relates to a device and method for measuring flow direction and flow velocity in a hole. Background Art

[0002] Because the hydrodynamic conditions of groundwater in boreholes are generally weak and the groundwater flows slowly, the technical requirements for flow direction and velocity measurement are extremely stringent. In the micro-scale range, the flow of groundwater may be more complex and unstable. The water flow may be restricted and affected by various factors such as stratum structure, porosity, and permeability, resulting in complex and changeable flow patterns. In boreholes, groundwater may be disturbed by vertical turbulence. Vertical turbulence is caused by the vertical movement of water in the borehole, which may mask or interfere with the information of horizontal flow, making measurement more difficult.

[0003] Conventional measurement methods are also mainly aimed at large-scale ranges. The flow direction and velocity measurement based on the group-hole aquifer mainly include isotope tracing and natural potential method. For the isotope tracing method, factors such as the particle size, release amount and release mode of the tracer will affect its distribution and diffusion in the borehole. In a single borehole, especially in a small range, the distribution of the tracer is not enough to provide sufficient information to accurately determine the flow direction and velocity. The isotope tracing method usually requires measurements in multiple boreholes to obtain sufficient data to determine the flow direction and velocity. In a turbulent state, the tracer may flow along different paths and may even be adsorbed on the borehole wall or aquifer medium, thereby affecting the accuracy of the measurement results; for the natural potential method, in a small scale range, the signal of the natural electric field is weak and easily interfered by noise, resulting in a reduction in the accuracy of the measurement results. Vertical turbulence will also cause an uneven distribution of positive and negative ions in the water flow, thereby affecting the distribution of the natural electric field. In a turbulent state, the electric field may become complex and difficult to interpret, making the determination of flow direction and velocity difficult. Therefore, the above measurement method is also unable to measure the groundwater flow direction and velocity within a small scale in a single borehole, and cannot avoid the vertical turbulence interference of groundwater.

[0004] Chinese patent CN109898993A discloses a device for measuring groundwater flow velocity and direction in a vertical borehole. The azimuth of the electromagnetic current meter can be measured using a three-dimensional electronic compass sensor, which solves the problem of difficulty in measuring groundwater flow velocity and flow direction in a vertical borehole. However, at a microscale, groundwater flow may be affected by a variety of factors, such as stratum structure, porosity, permeability, etc. These factors increase the instability and complexity of water flow, making measurement more difficult. The structure and size of the detector body of the above patent limit its application within a microscale range. For example, components such as the glass chamber and the current meter protection frame occupy a certain space, making the detector unable to fully adapt to the microscale measurement environment; the electromagnetic current meter is located below the detector body and directly contacts the water body. This installation method cannot avoid the interference of vertical turbulence on its measurement results, because vertical turbulence may occur at any position in the borehole, and the electromagnetic current meter can only measure the flow velocity and flow direction at its location. Summary of the invention

[0005] In order to overcome the shortcomings of the above-mentioned prior art, the purpose of the present invention is to provide a device and method for measuring the flow direction and flow velocity in a hole, aiming to solve the technical problems that the prior art cannot measure the flow direction and flow velocity of groundwater within a small scale in a single borehole and cannot avoid the vertical turbulence interference of groundwater during the measurement process.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions: The present invention provides a device for measuring flow direction and flow velocity in a hole, comprising an upper tank body, a lower tank body and a data collector, wherein the upper tank body is connected to the lower tank body, and a certain distance is left between the bottom of the upper tank body and the top of the lower tank body; An upper tank cover is provided on the top of the upper tank body, and an upper tank base is provided on the bottom. A plurality of conductivity probes are provided on the lower edge of the upper tank base, and an electronic compass is provided inside each conductivity probe for determining the flow direction of groundwater in the hole; the conductivity probe is connected to the data collector through a conductivity connection line; A lower tank cover is provided on the top of the lower tank body, a lower tank base is provided on the bottom, a piston is provided inside the cavity of the lower tank body, a nozzle is provided on the lower tank cover, and a water inlet hole is provided on the lower tank base.

[0007] Furthermore, a consolidation point is provided inside the upper tank body, and the conductivity connection lines connected to the conductivity probe are gathered through the consolidation point and then connected to the data collector.

[0008] Further preferably, the fixing point is arranged on the upper tank base.

[0009] Furthermore, the top of the consolidation point has a wire channel vertically passing through the top of the upper tank body, the outer side of the wire channel is covered with an armored outer skin, and the conductivity connection line is collected through the consolidation point and then connected to the data collector through the wire channel.

[0010] Furthermore, the plurality of conductivity probes are arranged in a circumferential distribution along the lower edge of the upper tank base.

[0011] Furthermore, eight conductivity probes are provided.

[0012] Furthermore, there are a plurality of nozzles, which are distributed in a circle near the center point of the lower tank top cover.

[0013] Furthermore, the number of the nozzles is 8.

[0014] Furthermore, the distance between the upper tank body and the lower tank body is 3cm-5cm.

[0015] Furthermore, the water inlet cooperates with the nozzle to form a pressure difference in the measuring device. This design helps to guide the water flow to pass through the measuring area more smoothly and reduce the influence of vertical turbulence.

[0016] Furthermore, a piston is arranged inside the cavity of the lower tank body, and can move longitudinally under the action of groundwater pressure.

[0017] Furthermore, the upper tank body and the lower tank body are connected via a connecting boss.

[0018] The present invention also provides a method for determining the flow direction and velocity of groundwater in a borehole, which specifically includes the following contents: 1) Fill the lower tank with conductive liquid and put it into the drill hole to place the test point; 2) Collect the conductivity values ​​of each conductivity probe and draw a curve of conductivity change over time at different azimuth points based on the measured values; 3) Compare the curves of conductivity changes at different directions over time with the standard curves, and find the curve that is closest to the standard curve. The groundwater flow velocity corresponding to this curve is the final flow velocity of the groundwater at the test point; and the orientation of the electronic compass of the corresponding conductivity probe is obtained through the conductivity value of the closest curve, and then the final flow direction of the groundwater to be tested is obtained.

[0019] Furthermore, in step 1), the point to be measured is the maximum water outlet point measured.

[0020] Furthermore, in step 2), the conductivity value of each conductivity probe is collected within a range of 10 to 15 minutes.

[0021] Furthermore, the standard curve diagram in the step is obtained by building a liquid-solid two-phase groundwater seepage physical similarity material simulation experimental device based on the physical similarity simulation criterion, wherein the aquifer thickness in the simulation experimental device is controlled at 10-15 cm, the borehole diameter is set between 50 mm and 300 mm, and the groundwater flow rate in the borehole can be adjusted between 100 μm / s and 10000 μm / s according to the change of the hydraulic gradient. The measuring device is sequentially loaded with a conductivity liquid with a mass percentage concentration of 0.5% to 2.0%, and the measuring device is submerged to the aquifer position, and the conductivity probe is preferably located at 1 / 2 of the thickness of the aquifer. Under the above parameter setting conditions, the groundwater seepage physical similarity material simulation experiment is carried out respectively, and the conductivity value of each conductivity probe in the measuring device is measured in a certain period of time, and a standard curve diagram of the conductivity changing with time in different directions is drawn; Among them, any two conductivity probes facing each other in the measuring device are used as references to keep the measuring device consistent with the groundwater flow direction in the physical similar material simulation experiment.

[0022] Further, the borehole diameters are selected to be 50 mm, 100 mm, 150 mm, 200 mm, 250 mm, and 300 mm, respectively, the conductivity liquid concentrations are selected to be 0.5%, 1.0%, 1.5%, and 2.0%, respectively, and the groundwater flow velocity is selected to be no less than 199 between 100 μm / s and 10000 μm / s at intervals of 50 μm / s; Among them, adjusting the hydraulic gradient specifically refers to adjusting the height difference between the water inlet and the water outlet in the simulation test device. The greater the height difference, the greater the hydraulic gradient and the greater the flow rate. Conversely, the smaller the hydraulic gradient; By building a simulation experimental device of liquid-solid two-phase groundwater seepage with physically similar materials and conducting simulation experiments under different parameter settings, standard curves of conductivity changes over time in different directions can be drawn. These standard curves provide a reliable reference benchmark for subsequent actual measurements. The establishment of the standard curve takes into account a variety of influencing factors, including aquifer thickness, borehole diameter, groundwater flow rate, and conductivity fluid concentration, thereby ensuring the accuracy and reliability of the measurement results; Furthermore, according to the shape of the salinization logging curve and the test results in the early stage of drilling, the different water-yielding points of the aquifer are delineated in layers and sections, and the maximum water-yielding point is selected in the same aquifer; Among them, the basic method of salinization logging is to inject salt solution into the borehole, dive the conductivity probe to the bottom, and test the conductivity values ​​in different aquifers from bottom to top. The test result is a salinization logging curve with the vertical axis being the depth of the borehole and the horizontal axis being the resistivity value. The water-yielding section is characterized by water-yielding points, good hydrodynamic conditions, fast groundwater flow, and fast dilution of salt solution, which leads to high resistivity and is manifested as a horizontal bulge on the curve; the non-water-yielding layer has poor hydrodynamic conditions, slow groundwater flow, and slow dilution of salt solution, which leads to slight changes in conductivity and is manifested as a vertical straight line on the curve. Different water-yielding points can be delineated based on the above-mentioned salinization logging curve, and the maximum water-yielding point can be determined based on the height of the bulge.

[0023] More preferably, the conductive liquid is a sodium chloride solution.

[0024] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a device for measuring flow direction and flow velocity in a hole. By arranging a plurality of conductivity probes at the lower edge of the upper tank base, the conductivity information of groundwater in different directions can be obtained. In a micro-scale range, the change of groundwater flow velocity will lead to a significant change of the conductivity value. By measuring the conductivity value of the conductivity probe, the flow velocity of groundwater can be obtained. At the same time, an electronic compass is arranged inside the conductivity probe to accurately measure the flow direction. The electronic compass has the characteristics of high sensitivity and high resolution. Groundwater will carry weak magnetic field information during the flow process. The electronic compass can accurately capture this information and judge the flow direction accordingly. In addition, by designing a certain distance between the upper tank body and the lower tank body, it is helpful to reduce the interference of the vertical turbulence of groundwater on the measurement. Since there is a certain space between the upper tank body and the lower tank body, the vertical turbulence is difficult to be directly transmitted to the conductivity probe, thereby reducing the measurement error, and by separating the upper and lower tank bodies, the influence of this vertical movement on the horizontal flow velocity and flow direction measurement can be isolated to a certain extent. The measuring device not only realizes the simultaneous measurement of the flow direction and velocity of groundwater in a single borehole within a micro-scale range, but also avoids the vertical turbulence interference of groundwater. The overall structure is simple and the measurement results are accurate.

[0025] Furthermore, the setting of the fixing point effectively supports and protects the conductivity connecting wire, avoids measurement errors caused by movement or damage of the connecting wire, and improves the stability and durability of the entire measuring device.

[0026] Furthermore, the armored outer sheath not only provides additional protection, but also organizes the direction of the conductivity connection line in an orderly manner through its internal channels, reducing clutter and interference, enhancing the connection line's ability to resist external interference, and improving measurement accuracy.

[0027] The present invention also provides a method for measuring the flow direction and velocity in a hole. First, the lower tank of the measuring device is filled with conductive liquid and then put into the borehole and placed at the maximum water outlet point, which helps to more accurately measure the flow of groundwater. At this point, the groundwater flow mainly flows in the horizontal direction, which avoids the interference of the measuring device by vertical turbulence; secondly, within a certain period of time, the conductivity values ​​of the conductivity probes in different directions are collected in real time. This step ensures the continuity and integrity of the data and provides sufficient information for subsequent data processing and analysis; finally, the reference function of the standard curve is fully utilized, and the final flow velocity and final flow direction of the groundwater to be measured can be accurately obtained by comparing and analyzing the curve shape. This method combines the advantages of electronic compass and conductivity measurement, and can simultaneously measure the flow direction and velocity of groundwater. By collecting the conductivity values ​​of each conductivity probe, and drawing a curve diagram of the change of conductivity in different directions over time based on the conductivity value, the morphology is compared with the standard curve diagram obtained by the simulation experiment of the physical similarity of groundwater seepage, so as to determine the flow velocity and direction of the groundwater to be measured. This method combines physical simulation and measured data. It is not only suitable for groundwater measurement in a single borehole, but also can adjust the structure and parameters of the device as needed to meet the measurement needs at different depths and different hydrogeological conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a front view of the measuring device; Figure 2 It is a top view of the base of the upper tank of the measuring device; Figure 3 It is a top view of the lower tank cover of the measuring device; Figure 4 This is a front view of the lower tank top cover of the measuring device; Figure 5 This is a bottom view of the lower tank base; Figure 6 The standard curve diagram of the change of conductivity over time obtained in Example 2; Figure 7 This is a logging curve diagram of the early stage of drilling saltation obtained in Example 2; Figure 8 The curve diagram of the conductivity change over time obtained in Example 2; Fig. 9 This is a morphology comparison diagram obtained in Example 2.

[0029] Among them: 1-upper tank body; 2-upper tank top cover; 3-upper tank base; 4-conductivity probe; 5-conductivity connecting line; 6-consolidation point; 7-armored outer skin; 8-data collector; 9-lower tank body; 10-lower tank top cover; 11-connecting boss; 12-nozzle; 13-piston; 14-lower tank base. DETAILED DESCRIPTION

[0030] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0031] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0032] The present invention is further described in detail below with reference to the accompanying drawings and embodiments: Example 1 The device for measuring flow direction and velocity in a hole provided by the present invention comprises: the upper device is an upper tank body 1, the upper part of the upper tank body 1 is an upper tank top cover 2, and the lower part is an upper tank base 3. The upper tank base 3 is provided with conductivity probes 4 divided into 8 equal parts along the edge according to the circumference, wherein the conductivity probe 4 is connected to the consolidation point 6 through the conductivity connection line 5 and then passes through the armored outer skin 7 to be connected to the data acquisition device 8, and the armored outer skin 7 is connected to the consolidation point 6 and penetrates the upper tank top cover 2 from the center position. Other conductivity probes are connected in the same manner as above. Among them, an electronic compass is provided inside each azimuth conductivity probe for determining the direction of groundwater flow.

[0033] The lower device is a lower tank body 9, the upper part of the lower tank body 9 is set as a lower tank body top cover 10, and the lower part is set as a lower tank body base 14. A nozzle 12 is set on the lower tank body top cover near the center point and divided into 8 equal parts according to the circumference. A connecting boss 11 is set at the center point of the lower tank body top cover 10 to connect with the upper tank base 3. A piston 13 is set inside the cavity of the lower tank body 9 for moving up and down under the action of groundwater pressure, thereby driving the conductive liquid to spray out from the nozzle 12.

[0034] Working principle: When the device is put into the borehole and is in the groundwater environment, the groundwater will penetrate into the lower tank body 9 from the central opening of the lower tank base 14. As the entire device is completely submerged below the water surface, because the water pressure difference between the nozzle 12 and the lower tank base 14 exists and remains constant, the constant water pressure will always act on the piston 13. Under the action of the water pressure, the piston 13 begins to move upward. When the piston 13 moves to a certain position, it will push the conductive liquid in the lower tank body 9 to spray out through the nozzle 12. The setting of the nozzle 12 allows the conductive liquid to be sprayed evenly from all directions. When the water body is static, the diffusion speed of the conductive liquid in the water is consistent, ensuring that the values ​​measured by the conductivity probes 4 in all directions are similar. When groundwater undergoes dynamic changes, the flow caused by groundwater recharge from a certain direction will lead to differences in the measurement results of the conductivity probe 4 in that direction. The closer to the groundwater recharge source, the greater the difference in the measurement results of the conductivity probe 4. Since the conductivity probe 4 itself has an electronic compass, it can measure the flow direction of groundwater, and thus determine the groundwater recharge source and flow direction. In addition, based on the standard curve of conductivity change over time established by the simulation experiment of physical similar materials of groundwater seepage, further comparative analysis can be performed to obtain the groundwater flow velocity.

[0035] Example 2 See also Figure 6-8 Taking the drilling hole diameter of 150mm and the conductivity liquid concentration of 1% as an example, the specific implementation steps are as follows: 1) Set the borehole diameter to 150 mm, the aquifer thickness to 10 cm, the conductivity concentration of the measuring device to 1%, and the groundwater flow velocity to 100 μm / s~800 μm / s, and conduct a groundwater seepage physical similarity material simulation experiment. Place the measuring device in the borehole, and use the two relative conductivity probes 4 as references. Rotate the measuring device to be consistent with the groundwater flow direction. The position of the submerged aquifer is based on the conductivity probe 4 being located at 1 / 2 of the aquifer. Measure the conductivity within 10~15 minutes, and establish the following: Figure 6 Standard curve graph of conductivity versus time shown; 2) Submerge the conductivity probe 4 to the bottom and test the conductivity values ​​of aquifers at different depths from bottom to top to obtain the following values: Figure 7 The early stage of the drilling salt logging curve shown in the figure shows that according to the early stage of the drilling salt logging curve and the test results, the resistivity is the largest at the vertical depth of 52m in the borehole, so this position is the maximum water point. After the measuring device is filled with conductive fluid, it is put into the borehole and placed at the maximum water point; 3) Within 10 to 15 minutes, use the measuring device to collect the conductivity values ​​of each probe and plot them as follows: Figure 7 The conductivity curves of different azimuth points as a function of time are shown; 4) Draw the Figure 7The conductivity versus time curve shown is consistent with the above established Figure 6 Compare the shape of the standard curve shown in the figure, and find the groundwater flow direction and flow velocity that are closest to the standard curve as the final flow direction and flow velocity of the groundwater to be tested. Figure 8 It is judged that the actual flow velocity in the borehole is 800μm / s, and the flow direction is the electronic compass azimuth of the conductivity probe corresponding to the actual conductivity curve, which is the groundwater flow direction. The azimuth displayed by the electronic compass of the corresponding conductivity probe is 0°, which is the north direction. Therefore, the final groundwater flow direction is from north to south.

[0036] The above contents are only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A device for measuring flow direction and flow velocity in a hole, characterized in that: It comprises an upper tank body (1), a lower tank body (9) and a data acquisition device (8), wherein the upper tank body (1) is connected to the lower tank body (9), and a certain distance is left between the bottom of the upper tank body (1) and the top of the lower tank body (9); An upper tank cover (2) is provided on the top of the upper tank body (1), and an upper tank base (3) is provided on the bottom. A plurality of conductivity probes (4) are provided on the lower edge of the upper tank base (3). Each conductivity probe (4) is provided with an electronic compass for determining the flow direction of groundwater in the hole. The conductivity probes (4) are connected to a data acquisition device (8) via a conductivity connection line (5); The top of the lower tank body (9) is provided with a lower tank cover (10), and the bottom is provided with a lower tank base (14). A piston (13) is provided inside the cavity of the lower tank body (9). The lower tank cover (10) is provided with a nozzle (12), and the lower tank base (14) is provided with a water inlet hole.

2. A device for measuring flow direction and flow velocity in a hole according to claim 1, characterized in that: A consolidation point (6) is provided inside the upper tank body (1), and the conductivity connection lines (5) connected to the conductivity probe (4) are connected to the data acquisition device (8) after being collected through the consolidation point (6).

3. A device for measuring flow direction and flow velocity in a hole according to claim 2, characterized in that: The top of the consolidation point (6) has a wire channel that vertically passes through the top of the upper tank body (1), and the outer side of the wire channel is covered with an armored outer skin (7). The conductivity connection line (5) is collected through the consolidation point (6) and then connected to the data acquisition device (8) through the wire channel.

4. A device for measuring flow direction and flow velocity in a hole according to claim 1, characterized in that: The plurality of conductivity probes (4) are arranged in a circumferential distribution along the lower edge of the upper tank base (3).

5. A device for measuring flow direction and flow velocity in a hole according to claim 4, characterized in that: The number of conductivity probes (4) is 8.

6. A device for measuring flow direction and flow velocity in a hole according to claim 1, characterized in that: A plurality of nozzles (12) are provided, and the plurality of nozzles (12) are arranged in a circumferential distribution near the center point of the lower tank top cover (10).

7. A device for measuring flow direction and flow velocity in a hole according to claim 6, characterized in that: The number of nozzles (12) is 8.

8. A device for measuring flow direction and flow velocity in a hole according to any one of claims 1 to 7, characterized in that: The upper tank body (1) and the lower tank body (9) are connected via a connecting boss.

9. A device for measuring flow direction and flow velocity in a hole according to any one of claims 1 to 7, characterized in that: The distance between the upper tank body (1) and the lower tank body (9) is 3 cm to 5 cm.

10. A method for measuring water flow direction and flow velocity using a device for measuring flow direction and flow velocity in a hole as claimed in any one of claims 1 to 9, characterized in that: The following steps are involved: 1) Fill the lower tank (9) with conductive liquid and place it into the drill hole to be tested; 2) collecting the conductivity values ​​of each conductivity probe (4), and drawing a curve diagram of the conductivity change at different positions over time based on the conductivity values; 3) Compare the curves of conductivity changes at different orientations over time with the standard curves, and find the curve that is closest to the standard curve. The groundwater flow velocity corresponding to the curve is the final flow velocity of the groundwater at the test point. The orientation of the electronic compass of the corresponding conductivity probe (4) is obtained through the conductivity value of the closest curve, and the final flow direction of the groundwater to be tested is obtained.

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