Device and method for detecting integrity of geomembrane anti-seepage system in operation period of plain reservoir

Abstract

The invention relates to the technical field of water conservancy project exploration, in particular to a device and method for detecting the integrity of a geomembrane anti-seepage system in the plain reservoir operation period. The detection device comprises a pontoon; the underwater suspension cable is dragged at the tail part of the pontoon; the underwater cable dragging unit is connected to the front end of the underwater suspension cable; the tail end suspension device is connected to the tail end of the underwater suspension cable; the underwater cable dragging unit is used for providing horizontal pulling force in the measurement process, the tail end suspension device is used for controlling the suspension depth of the tail end of the underwater suspension cable, and the underwater cable dragging unit and the tail end suspension device keep the same suspension depth in the measurement process. According to the method, the problems that the front end of the cable is easily lifted by a pontoon, the posture is unstable and the cable is easily interfered by stormy waves in the prior art are solved, and an accurate division evaluation and result interpretation method is provided for judging the integrity of a geomembrane anti-seepage system in the operation period of a plain reservoir.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of water conservancy engineering exploration, and particularly relates to a device and method for detecting integrity of a geomembrane anti-seepage system during operation of a plain reservoir. BACKGROUND

[0002] Plain reservoirs are usually built in alluvial plain regions, which have high soil permeability and complex geological conditions, and therefore have very high requirements for the anti-seepage performance of the reservoirs. Geomembranes have become the core anti-seepage material for such reservoirs due to their extremely low permeability, good deformation adaptability, and economical and efficient construction characteristics. A typical geomembrane anti-seepage and air exhaust system in a reservoir basin is composed of an overlying protective layer (such as a soil layer), a geomembrane body, and a check valve below the geomembrane for draining water and air. During long-term operation, the geomembrane system is easily damaged by factors such as sediment deposition, water flow scouring, earthquakes, changes in groundwater level, and stratum settlement, or fails due to improper protective layer thickness (too thin causing the geomembrane to float and lose stability, or too thick burying the check valve and causing gas accumulation and swelling). Once leakage occurs, it will seriously weaken the water storage capacity of the reservoir and threaten the overall structural safety. Therefore, it is urgent to efficiently and accurately detect and evaluate the integrity of the geomembrane anti-seepage system in the reservoir basin area (including whether the geomembrane is damaged and whether the protective layer thickness distribution is reasonable) during operation.

[0003] A rapid scanning device and method for detecting water seepage are disclosed in the prior art, which includes a device mounting platform and a cable. An electrical method instrument is installed on the device mounting platform, and the cable is divided into an electrode part and a non-electrode part. When the scanning device is working, the cable with electrodes is below the water surface, and the front end of the cable without electrodes is above the water surface, so as to detect and scan the entire target water body.

[0004] The above prior art has the following problems: Firstly, the measurement efficiency is limited and susceptible to interference. Although ship-borne towing measurement has improved efficiency compared to fixed measurement, the depth control and posture control of the suspended cable are insufficient. During the ship's progress, the front end of the cable is easily lifted, causing the overall posture of the cable to be unstable (not horizontal), and being susceptible to water surface wind and wave disturbances and ship progress disturbances, which limits the measurement line layout and positioning accuracy, and makes the data quality unstable, making it difficult to achieve truly efficient, continuous, and large-area scanning.

[0005] Secondly, the reliability and accuracy of the measurement result interpretation are insufficient. The existing technology mainly relies on the inversion of the resistivity profile to roughly estimate the approximate position of the geomembrane and the rough thickness of the protective layer through the resistivity threshold and abnormal morphology. However, the geomembrane itself is only a few millimeters thick, and the thickness of the overlying protective layer usually varies between 1-2 meters, and the existing inversion method and interpretation technology lack strict evaluation of the quality of the measurement data and effective means for accurate calculation and division of the thickness of the protective layer and the position of the geomembrane. The identification accuracy of the over-thick (valve covering) area, the under-thick (insufficient anti-floating) area and the small-scale damage point is poor, which leads to inaccurate and unreliable judgment of the integrity state of the anti-seepage system. SUMMARY

[0006] In view of the deficiencies of the prior art, the purpose of the embodiments of the present application is to provide a device and method for detecting the integrity of the geomembrane anti-seepage system of a plain reservoir in operation.

[0007] In order to achieve the above-mentioned purpose, the embodiments of the present application provide the following technical solutions: A device for detecting the integrity of the geomembrane anti-seepage system of a plain reservoir in operation, comprising: a floating boat; a water-suspended cable, which is dragged at the tail of the floating boat, and a plurality of electrodes are arranged on the water-suspended cable; an underwater cable dragging unit connected to the front end of the water-suspended cable; a tail-suspended device connected to the end of the water-suspended cable; wherein the underwater cable dragging unit is used to provide horizontal tension during measurement, the tail-suspended device is used to control the suspended depth of the end of the water-suspended cable, the underwater cable dragging unit and the tail-suspended device maintain the same suspended depth during measurement, and the speed of the floating boat sailing is consistent with the forward speed of the underwater cable dragging unit.

[0008] The detection device of the present application mainly relies on the floating boat as the basic platform. The floating boat not only provides the necessary buoyancy and carrying capacity, but also is equipped with a propulsion power device, which can autonomously sail to different measurement areas of the reservoir basin, ensuring the flexibility and efficiency of the detection work. The water-suspended cable is dragged at the tail of the floating boat, and a plurality of electrodes are arranged thereon. These electrodes can sense and transmit electrical signals to provide basic data support for subsequent resistivity calculation and anti-seepage system integrity evaluation.

[0009] The underwater cable towing unit is connected to the front end of the water-suspended cable, mainly undertakes the function of providing horizontal tension for the cable, ensures that the cable maintains a stable tension state in the water, avoids excessive swing or winding of the cable due to water flow impact or floating boat travel, and guarantees the smoothness of the measurement process and the continuity of data acquisition. The tail end suspension device is connected to the end of the water-suspended cable, controls the suspension depth of the end of the cable, so that the cable can be stably suspended in the water according to the preset depth, thereby ensuring that the electrode and the geomembrane anti-seepage system are in the best relative position relationship, and improving the accuracy of the measurement data.

[0010] In the measurement operation, the underwater cable towing unit and the tail end suspension device work cooperatively, the front end underwater cable towing unit performs depth setting towing, and the tail end suspension device provides depth setting suspension. The speed difference between the underwater cable towing unit and the tail end suspension device straightens the cable, avoids the problem that the front end of the cable is lifted to affect the horizontal posture of the suspended cable, effectively prevents the cable from being twisted or deformed due to the depth difference, and improves the quality of the measurement data. At the same time, the speed of the floating boat is consistent with the forward speed of the underwater cable towing unit. The synchronization of the speed can ensure that the front end of the cable is not affected by the towing force generated by the floating boat sailing, guarantee the posture of the cable in the water stable, and reduce the measurement error caused by the change of the posture.

[0011] Optionally, the underwater cable towing unit is installed in front of the first electrode at the front end of the water-suspended cable, and is connected to the power supply on the floating boat through a power line.

[0012] The towing unit is installed in front of the first electrode, which ensures that the action point of the towing force is located in front of the electrode array, so that the entire electrode array can maintain a horizontal posture during towing. The power supply is provided from the floating boat, which provides a stable and reliable power source for the underwater cable towing unit, ensuring its continuous working ability.

[0013] Optionally, cable buoyancy devices are arranged between the electrodes of the water-suspended cable, which provide additional buoyancy for the cable to balance the weight of the cable itself and the influence of external factors, and help to maintain the overall suspended state and predetermined depth of the cable. The cable buoyancy device works cooperatively with the underwater cable towing unit (providing the main gravity component) and the tail end suspension device (controlling the end depth) to maintain the stable suspended posture and depth of the entire measurement cable in the water.

[0014] Optionally, the cable buoyancy device is made of hollow hard plastic material and is fixed on the water-suspended cable by a detachable buckle.

[0015] The hollow hard plastic has small density and can provide sufficient buoyancy, and has high hardness and can resist certain water pressure, and is not easy to be deformed and damaged, thereby ensuring the reliability of long-term use. The detachable buckle facilitates the installation, disassembly, replacement or maintenance of the buoyancy device, and improves the maintainability and flexibility of the device.

[0016] Optionally, the embodiment of the present application also provides a detection method for integrity of geomembrane anti-seepage system of plain reservoir in operation period using the detection device, comprising: obtaining the resistivity of the stratum under the geomembrane in the reservoir basin, the minimum water depth of the reservoir basin and the average thickness of the overburden soil on the geomembrane; determining the suspension depth of the cable according to the minimum water depth of the reservoir basin; determining the electrode spacing according to the average thickness of the overburden soil on the geomembrane and the suspension depth of the cable; synchronously collecting the apparent resistivity data, the water depth of the reservoir and the resistivity data of the reservoir water in the measurement area through the electrode array suspended in the water according to the preset survey line; determining the resistivity threshold range of the overburden layer on the geomembrane based on the resistivity of the reservoir water and the resistivity of the stratum under the geomembrane; inverting the apparent resistivity data to obtain the resistivity profile of the bottom of the reservoir basin, identifying the reservoir water area, the overburden layer area on the geomembrane and the stratum area under the geomembrane in the resistivity profile according to the resistivity threshold range of the overburden layer on the geomembrane, and calculating the thickness of the overburden layer on the geomembrane; dividing the overburden layer into an over-thick area and an under-thin area based on the calculated thickness of the overburden layer on the geomembrane, and dividing the damaged area of the geomembrane based on the abnormal change of the resistivity of the stratum under the geomembrane.

[0017] The resistivity of the stratum under the geomembrane in the reservoir basin, the minimum water depth of the reservoir basin and the average thickness of the overburden soil on the geomembrane can be obtained through preliminary investigation by geological survey or water-based high-density electrical method, which provides a basis for subsequent cable setting. The suspension depth of the cable is determined according to the minimum water depth of the reservoir basin, which can ensure that the cable is close to the bottom of the reservoir basin and does not touch the bottom topography, avoiding topographic interference. The electrode spacing is determined according to the average thickness of the overburden soil on the geomembrane and the suspension depth of the cable, which can take into account the detection resolution and effective detection depth, ensuring that the overburden layer on the geomembrane and the damage of the geomembrane can be accurately detected.

[0018] The apparent resistivity data, the water depth of the reservoir and the resistivity data of the reservoir water are synchronously collected according to the preset survey line, which can be completed by the data acquisition unit on the floating boat in cooperation with the electrodes, the echo sounder depth unit and the water resistivity measurement sensor, ensuring the spatio-temporal consistency of the data. The threshold range is determined based on the resistivity of the reservoir water and the resistivity of the stratum under the geomembrane, which provides a standard for distinguishing different areas. Inverting the apparent resistivity data and identifying the areas can convert the original data into an analyzable geological profile. Calculating the thickness of the overburden layer and dividing the over-thick, under-thin and damaged areas makes full use of the data for depth interpretation, thereby realizing the comprehensive evaluation of the integrity of the geomembrane anti-seepage system of the plain reservoir in operation period, and providing accurate guidance for the safe management and maintenance of the reservoir.

[0019] Optionally, the determination of the cable suspension depth satisfies: the reservoir basin minimum water depth minus 2 meters is less than the cable suspension depth, and the cable suspension depth is less than the reservoir basin minimum water depth; the electrode spacing is greater than the average thickness of the overlying soil on the geomembrane and less than the cable suspension depth.

[0020] The range makes the cable suspended at a position close to the bottom of the reservoir basin, avoiding the influence of terrain undulations due to being too close to the water bottom, and shortening the distance to the geomembrane impermeable system to improve detection sensitivity. The electrode spacing is greater than the average thickness of the overlying soil on the geomembrane and less than the cable suspension depth, ensuring that the electrode spacing can cover the thickness range of the overlying protective layer on the geomembrane, while not reducing the resolution due to too large spacing, and effectively detecting the thin overlying protective layer on the geomembrane and small-sized geomembrane damage points, solving the contradiction between the electrode spacing and resolution and detection depth in the prior art.

[0021] Optionally, the determination of the resistivity threshold range of the overlying protective layer on the geomembrane is: when the reservoir water resistivity is greater than the groundwater resistivity, the resistivity threshold range of the overlying protective layer on the geomembrane is greater than the resistivity of the underlying stratum and less than the reservoir water resistivity; when the reservoir water resistivity is less than the groundwater resistivity, the resistivity threshold range of the overlying protective layer on the geomembrane is greater than the reservoir water resistivity and less than the resistivity of the underlying stratum.

[0022] Based on the size relationship between the reservoir water resistivity and the groundwater resistivity, the threshold range can accurately define the resistivity range of the overlying protective layer. When the reservoir water resistivity is greater than the groundwater resistivity, the threshold range is between the resistivity of the underlying stratum and the reservoir water resistivity, which can distinguish the reservoir water (low resistivity), the overlying protective layer on the geomembrane (medium resistivity) and the underlying stratum (high resistivity); when the reservoir water resistivity is less than the groundwater resistivity, the threshold range is between the reservoir water resistivity and the resistivity of the underlying stratum, which can also clearly divide the three regions. This dynamic threshold determination method adapts to the resistivity difference under different hydrogeological conditions, provides a reliable basis for subsequent regional identification and thickness calculation, and improves the accuracy of the detection result.

[0023] Optionally, the calculation of the thickness of the overlying protective layer on the geomembrane includes: identifying a region in the resistivity profile where the difference between the resistivity value and the reservoir water resistivity is less than a first threshold value, and extracting the bottom boundary depth of the region; identifying a region in the resistivity profile where the difference between the resistivity value and the resistivity of the underlying stratum is less than a second threshold value, and extracting the top boundary depth of the region; subtracting the bottom boundary depth from the top boundary depth to obtain the thickness of the overlying protective layer on the geomembrane.

[0024] In the resistivity profile, a region where the difference between the resistivity value and the reservoir water resistivity is less than a first threshold value is identified, which is the reservoir water region, and the bottom boundary depth is the interface between the reservoir water and the protective layer above the membrane; a region where the difference between the resistivity value and the resistivity of the formation below the membrane is less than a second threshold value is identified, which is the formation below the membrane region, and the top boundary depth is the interface between the protective layer above the membrane and the formation below the membrane, and the geomembrane is located at the top boundary of the formation below the membrane. The difference between the two is the actual thickness of the protective layer above the membrane. This calculation method accurately locates the interface and avoids errors caused by rough estimation, and can accurately reflect the thickness of the protective layer above the membrane, providing a quantitative basis for determining whether the protective layer meets the requirements.

[0025] Optionally, the division of the over-thick region and the over-thin region of the protective layer is based on the minimum thickness of the protective layer of the geomembrane anti-seepage system and the height of the air outlet of the check valve from the geomembrane; the region where the thickness of the protective layer above the membrane is less than the minimum thickness is the over-thin region of the protective layer; and the region where the thickness of the protective layer above the membrane is greater than the height is the over-thick region of the protective layer.

[0026] The minimum thickness that meets the anti-floating design is a critical value that ensures that the geomembrane will not float and lose stability under the action of external forces such as groundwater level fluctuations, and the height of the air outlet of the check valve from the geomembrane is a critical value that avoids burying the check valve in the protective layer and ensures that the gas and water below the membrane can be smoothly discharged. When the thickness of the protective layer above the membrane is less than the minimum thickness, the gravity provided is not enough to balance the buoyancy, and it belongs to the over-thin region; when the thickness is greater than the height of the check valve, the function of the check valve is affected, and it belongs to the over-thick region. This division method considers the key safety factors of the geomembrane anti-seepage system and can accurately evaluate the safety of the protective layer, solving the problem of ambiguous judgment of the protective layer in the prior art.

[0027] Optionally, the division of the geomembrane damage region is as follows: when the reservoir water resistivity is less than the groundwater resistivity, the region in the resistivity profile where the resistivity value is less than the resistivity of the formation below the membrane is identified as the geomembrane damage region; when the reservoir water resistivity is greater than the groundwater resistivity, the region in the resistivity profile where the resistivity value is greater than the resistivity of the formation below the membrane is identified as the geomembrane damage region.

[0028] The geomembrane damage area division method is based on the principle that a conductive path is formed between reservoir water and the stratum under the geomembrane after the geomembrane is damaged, causing abnormal changes in local resistivity.When the resistivity of the reservoir water is less than the resistivity of the groundwater, the reservoir water seeps into the stratum under the geomembrane through the damage, which reduces the resistivity of the area, and thus the area with resistivity less than that of the stratum under the geomembrane is the damage area; when the resistivity of the reservoir water is greater than the resistivity of the groundwater, the seepage of the reservoir water increases the resistivity of the area, and thus the area with resistivity greater than that of the stratum under the geomembrane is the damage area. This method of identifying the damage area according to the abnormal changes in resistivity can accurately locate small damage points and solve the problem of difficulty in detecting small damage in the prior art.

[0029] The one or more technical solutions provided in the embodiments of the present application have at least the following technical effects or advantages: 1、The detection device of the present application provides forward horizontal tension through the underwater cable towing unit, and the tail end suspension device provides depth suspension, both of which work together and at the same depth to ensure that the entire underwater suspended cable maintains a straight state and stable suspension depth during the towing process, effectively solving the problems of the prior art, such as the front end of the cable being easily lifted by the floating boat, unstable posture, and being easily disturbed by wind and waves. The design of the floating boat speed being consistent with the underwater cable towing unit speed makes the cable part in front of the underwater cable towing unit not subject to tension, further avoiding the lifting or depth change caused by the floating boat directly pulling the front end of the cable, and the device eliminates the water floating and floating device, avoiding the influence of waves caused by wind and waves on the water surface and the movement of the boat on the suspended cable, i.e. not affected by weather, wind and waves, etc., ensuring the stability of the measurement cable posture.

[0030] 2、The method of the present application realizes reliable interpretation of the electrical detection data of the geomembrane anti-seepage system of the plain reservoir, overcomes the limitations of roughly estimating the approximate position of the geomembrane and estimating the thickness of the protection layer through the resistivity profile, delineates the reservoir water and stratum under the geomembrane area through the resistivity threshold range of the protection layer above the membrane, calculates the thickness of the protection layer above the membrane and divides the protection layer of the geomembrane anti-seepage system into thin and thick areas, and defines the geomembrane damage area, providing an accurate division evaluation and result interpretation method for judging the integrity of the geomembrane anti-seepage system of the plain reservoir during operation.

[0031] 3、The present application uses the geomembrane anti-seepage system integrity detection device and method suspended in water to avoid the low efficiency of the existing fixed water and underwater electrical measurement, without the need to anchor both ends of the cable, and without being disturbed by wind and waves, so that continuous measurement of the geomembrane anti-seepage system in the reservoir area can be realized, and the method is suitable for rapid measurement of large-area plain reservoirs.

[0032] 4、The device and method of the present application improve the effective detection depth of the towed continuous measurement, so that the technical method can obtain detection results covering the impermeable area of the geomembrane at any water depth, avoiding the limitation of selecting electrode spacing according to water depth, improving the detection resolution of the waterborne electrical method and the identification accuracy of the geomembrane impermeable system anomaly, so that the device and method can be applied to detection during the operation of the plain reservoir.

[0033] The advantages of the additional aspects of the present application will be given in the following description, some of which will become apparent from the following description, or be understood through practice of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0034] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or prior art description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments described in the present application, and other drawings can also be obtained by those skilled in the art without creative labor on the basis of these drawings. In addition, the sizes or distances between each other are exaggerated for showing the positions of the components, and the schematic diagram is only used for illustration.

[0035] Figure 1 The schematic diagram of the device for detecting the integrity of the geomembrane impermeable system of the plain reservoir during operation provided by one or more embodiments of the present application; Figure 2 The schematic diagram of the method for detecting the integrity of the geomembrane impermeable system of the plain reservoir during operation provided by one or more embodiments of the present application; Figure 3 The schematic diagram of the relationship between the cable suspension depth and the minimum water depth of the reservoir basin and the relationship between the electrode spacing and the thickness of the protective layer provided by one or more embodiments of the present application; Figure 4 The schematic diagram of the stratigraphic resistivity profile of the reservoir water layer, the protective layer above the membrane and the stratum below the membrane provided by one or more embodiments of the present application; Figure 5 The schematic diagram for distinguishing the area with too thin and too thick thickness of the protective layer above the membrane provided by one or more embodiments of the present application.

[0036] In the figure: 1, floating boat; 2, waterborne propulsion power device; 3, data acquisition unit; 4, mobile positioning unit; 5, data real-time display terminal; 6, sonar depth measurement unit; 7, water body resistivity measurement sensor; 8, power line; 9, underwater cable towing unit; 10, suspended cable in water; 11, water level sensor; 12, waterproof graphite electrode; 13, cable buoyancy device; 14, tail end suspension device; DETAILED DESCRIPTION It should be noted that the following detailed description is illustrative and is intended to further illustrate the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as commonly understood by those of ordinary skill in the art to which the present invention belongs. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0037] Example 1 The first aspect of the present invention provides a device for detecting the integrity of a geomembrane anti-seepage system during operation of a plain reservoir, such as Figure 1 As shown, including: The instrument equipment and power unit, whose main structure consists of a floating boat 1, a water propulsion power unit 2 is equipped on the rear fender of the boat, and a data acquisition unit 3, a mobile positioning unit 4, a sonar depth sounding unit 6 and a real-time data display terminal 5 are equipped inside the boat.

[0038] The data acquisition unit 3, the mobile positioning unit 4, and the sonar sounding unit 6 are all connected to the real-time data display terminal 5, which controls the synchronous acquisition of resistivity, position, and water depth information.

[0039] The bottom of the floating vessel 1 is equipped with a water resistivity measuring sensor 7, which records the resistivity of the reservoir water at a fixed frequency.

[0040] The underwater suspended cable 10 is towed at the tail of the floating vessel 1 and consists of 13 waterproof graphite electrodes 12 , the front end of which is connected to the data acquisition unit 3 via an aviation plug.

[0041] The underwater cable towing unit 9 (such as a small underwater thruster) is installed in front of the first electrode at the front end of the cable and is connected to the power supply on the floating vessel 1 using a power line 8 to provide horizontal tension for the suspended cable during the measurement process.

[0042] Three water level sensors 11 are provided at the front, middle and tail ends of the underwater suspended cable 10 to monitor the suspension depth of the cable during the measurement process, and a cable buoyancy device 13 is provided between the cable electrodes.

[0043] The cable buoyancy device 13 is hollow in design and made of hard plastic. It is fixed to the suspension cable by a detachable buckle.

[0044] A tail end suspension device 14 (such as a float with adjustable buoyancy or a depth control wing) is provided at the tail end of the underwater suspended cable 10. This device only controls the cable suspension depth to achieve a fixed depth suspension of the tail end of the cable during the measurement process.

[0045] The cable buoyancy device 13 provides the main buoyancy for the suspension of the cable, and the cable's own weight and the underwater cable towing unit 9 provide the main gravity for the suspension of the cable. These two forces in opposite directions are equal in magnitude.

[0046] The sailing speed of the floating vessel 1 is consistent with the forward speed of the underwater cable towing unit 9 to ensure that the cable portion at the front end of the underwater cable towing unit 9 is a stress-free portion, thereby preventing the front end of the cable from being lifted by the floating vessel 1.

[0047] The underwater cable towing unit 9 and the tail suspension device maintain the same suspension depth during the measurement process to control the cable to suspend at a fixed depth in the water, and the tension between the two devices is used to maintain the straight state of the underwater suspended cable 10 during the measurement process.

[0048] In summary, this device allows the measuring cable to suspend above underwater terrain and obstacles, thereby achieving rapid and continuous measurement, and can quickly and accurately detect the integrity of the geomembrane anti-seepage system of plain reservoirs during operation. It has the advantages of high efficiency, high resolution, and strong applicability, avoiding the huge workload of underwater detection, and can provide stable high-resolution results under different water depth conditions. It provides a reliable device and method for achieving high-resolution rapid detection of the integrity of the geomembrane anti-seepage system in large-area plain reservoir basins.

[0049] Example 2 like Figure 2 As shown, this embodiment provides a method for detecting the integrity of a geomembrane anti-seepage system during operation of a plain reservoir, comprising the following steps: Step 1: Resistivity of the formation beneath the reservoir basin membrane , minimum water depth , Average thickness of soil covering (protective layer) on the membrane Preliminary investigation; the preliminary investigation can be carried out in the reservoir basin area using the high-density electrical method on water, and a comprehensive judgment can be made by combining the geophysical exploration results and the reservoir hydrogeological data.

[0050] Step 2: According to the minimum water depth of the reservoir Determining cable suspension depth ; Step 3: According to the average thickness of the soil on the membrane and cable suspension depth , determine the electrode spacing of the cable a ; Step 4: Assemble the detection device, plan the measurement line distribution on the map software according to the specific measurement requirements and area, and use the detection device to collect the apparent resistivity data in the measurement area according to the set measurement line. , reservoir water depth D , reservoir water resistivity ; In this example, a preliminary survey was conducted in the reservoir basin using the continuous high-density electrical method on water to obtain the resistivity of the subsurface strata in the reservoir basin. = 110 Ω·m, minimum water depth = 10 m, the overburden thickness of the membrane = 1.1 m, consistent with the construction profile of the reservoir hydrogeological data showing that the overburden thickness of the membrane is about 1 m. Therefore, the cable suspension depth in this method According to the minimum water depth of the reservoir basin Determined, should meet , that is, 8 m 10 m; the electrode spacing a of the cable is determined according to the average thickness of the overburden of the membrane And the cable suspension depth Should meet , a Is a positive integer, that is, 1.1 m 8 m. Figure 3 The schematic diagram for determining the cable suspension depth and electrode spacing in the embodiment is shown. Therefore, the electrode spacing 2 m cable with the suspension depth of 9 m is used for measurement in this embodiment. In the field application, the detection device shown in the figure is assembled, and the inclination of the rope caused by the ship is considered. The distribution of the measurement line is planned on the map software, and the apparent resistivity data Figure 1 , the reservoir water depth , the reservoir water resistivity D In the measurement area are collected according to the set measurement line.

[0051] Step 5: Determine the resistivity threshold range of the overburden protection layer of the membrane according to the reservoir water resistivity And the resistivity of the stratum under the membrane : When the reservoir water resistivity Is greater than the groundwater resistivity , meet ; when the reservoir water resistivity Is less than the groundwater resistivity , meet .

[0052] Step 6: Invert the apparent resistivity data , obtain the resistivity profile of the bottom of the reservoir basin, calculate the thickness of the overburden protection layer of the membrane according to the resistivity threshold range of the overburden protection layer of the membrane, and divide the position of the overburden protection layer and the geomembrane in the resistivity profile; The area with the resistivity value close to (determined according to the specific circumstances, for example, the difference is not more than 5%) the reservoir water resistivity In the resistivity profile of the bottom of the reservoir basin is the reservoir water area, and the area with the resistivity value close to (determined according to the specific circumstances, for example, the difference is not more than 5%) the resistivity of the stratum under the membrane In the resistivity profile is the stratum under the membrane area. The top boundary of the area with the resistivity value close to the resistivity of the stratum under the membrane In the resistivity profile is the position of the geomembrane. ​​

[0053] The thickness T of the protective layer on the membrane is calculated based on the resistivity threshold range of the protective layer on the membrane. First, the resistivity profile at the bottom of the reservoir is divided into the resistivity values ​​close to The area of ​​the bottom boundary of the area is extracted , and then divide the resistivity profile into sections with resistivity values ​​close to The area of ​​the top boundary of the area is extracted , the thickness of the protective layer on the film T satisfies: the thickness of the protective layer on the film T= - , where T>0.

[0054] Figure 4 The resistivity profile of the inverted measurement results of a single survey line is shown. According to the preliminary survey data in step 1, the resistivity of the formation under the membrane is = 110 Ω·m. The reservoir water resistivity collected in this survey is = 12 Ω·m, so the resistivity threshold range of the protective layer on the film should be 12 to 110 Ω·m. Figure 4 According to the above thresholds and ranges, the positions of the reservoir water layer, the protective layer on the membrane and the geomembrane in the resistivity profile are divided. According to the resistivity profile, the bottom boundary depth of the reservoir water layer can be extracted. and the depth of the top boundary of the submembrane stratum , that is, the bottom boundary of the resistivity value of 12 Ω·m area and the top boundary of the resistivity value of 110 Ω·m area in the resistivity profile. T= - Calculate the thickness of the protective layer on the membrane. In this embodiment, the thickness of the protective layer on the membrane is 0.7 μm. 1.6 m.

[0055] Step 7: According to the thickness of the protective layer area on the membrane T , divide the areas where the protective layer is too thick and too thin, and divide the geomembrane damaged area according to the abnormal resistivity of the stratum under the membrane.

[0056] Assume that the minimum thickness of the protective layer of the geomembrane anti-seepage system is , the height between the check valve outlet and the geomembrane is The normal range of the thickness T of the protective layer area on the film is , thickness less than The protective layer is too thin, and the area larger than The area with too thick protective layer.

[0057] like , then the resistivity of the damaged area of ​​the geomembrane is Should meet ;like , then the resistivity of the damaged area of ​​the geomembrane is Should be met .

[0058] Figure 5 The schematic diagram of dividing the over-thick and over-thin regions of the protective layer according to the thickness of the protective layer region on the membrane in the embodiment is shown. The thickness of the protective layer on the membrane is 0.7 m to 1.6 m, while the normal range of the protective layer on the membrane should be 0.85 m to 1.2 m, that is, the protective layer with a thickness less than 0.85 m provides a gravity less than the buoyancy of the groundwater level fluctuation, which will cause the deformation and damage of the geomembrane, and the protective layer with a thickness greater than 1.2 m will bury the outlet of the check valve, and the water and gas under the membrane cannot be discharged, resulting in the swelling and damage of the geomembrane.

[0059] Figure 4 Although the resistivity profile in the above does not disclose the abnormality caused by the damage of the geomembrane, the damage region of the geomembrane can still be determined according to the resistivity of the stratum under the membrane. If , the resistivity of the damage region of the geomembrane is Should be met For the embodiment, the resistivity of the reservoir water is less than the resistivity of the groundwater, and the resistivity of the damage region of the geomembrane is less than 110 Ω·m. While when , the resistivity of the damage region of the geomembrane should be greater than 110 Ω·m.

[0060] Although the specific embodiments of the present application are described above in combination with the drawings, it is not a limitation on the protection scope of the present application, and those skilled in the art should understand that various modifications or changes made by those skilled in the art on the basis of the technical solutions of the present application without creative labor are still within the protection scope of the present application.

Claims

1. A device for detecting the integrity of a geomembrane anti-seepage system during the operation of a plain reservoir, characterized in that: include: floating boat; An underwater suspended cable is towed at the stern of the floating vessel, wherein a plurality of electrodes are provided on the underwater suspended cable; an underwater cable towing unit connected to the front end of the submerged suspended cable; a tail end suspension device connected to the end of the submerged suspension cable; In which, the underwater cable towing unit is used to provide horizontal pulling force during the measurement process, and the tail end suspension device is used to control the suspension depth of the end of the underwater suspended cable. The underwater cable towing unit and the tail end suspension device maintain the same suspension depth during the measurement process, and the sailing speed of the floating vessel is consistent with the forward speed of the underwater cable towing unit.

2. The device for detecting the integrity of the geomembrane anti-seepage system during the operation period of a plain reservoir according to claim 1, characterized in that: The underwater cable towing unit is installed in front of the first electrode at the front end of the underwater suspended cable and is connected to the power supply on the floating vessel through a power line.

3. The device for detecting the integrity of the geomembrane anti-seepage system during the operation period of a plain reservoir according to claim 1, characterized in that: A cable buoyancy device is provided between the electrodes of the underwater suspended cable.

4. The device for detecting the integrity of a geomembrane anti-seepage system during operation of a plain reservoir according to claim 3, characterized in that: The cable buoyancy device is made of a hollow hard plastic material and is fixed to the underwater suspended cable via a detachable buckle.

5. A method for detecting the integrity of a geomembrane anti-seepage system in a plain reservoir during operation using the detection device according to any one of claims 1 to 4, characterized in that: include: Obtain the resistivity of the ground beneath the reservoir basin membrane, the minimum water depth of the reservoir basin, and the average thickness of the soil covering the membrane; Determine the cable suspension depth according to the minimum water depth of the reservoir; Determining the electrode spacing according to the average thickness of the soil covering the membrane and the cable suspension depth; Following the preset survey line, the electrode array suspended in the water synchronously collects the apparent resistivity data, reservoir water depth and reservoir water resistivity data within the measurement area; Determining a resistivity threshold range of the protective layer above the membrane based on the reservoir water resistivity and the resistivity of the formation below the membrane; Inverting the apparent resistivity data to obtain a resistivity profile of the reservoir basin bottom, identifying the reservoir water area, the upper membrane protective layer area, and the sub-membrane stratum area in the resistivity profile based on the resistivity threshold range of the upper membrane protective layer, and calculating the thickness of the upper membrane protective layer; The protective layer is divided into an overly thick area and an overly thin area based on the calculated thickness of the protective layer on the membrane, and the geomembrane damaged area is divided based on the abnormal change of the resistivity of the stratum under the membrane.

6. The method for detecting the integrity of a geomembrane anti-seepage system during operation of a plain reservoir according to claim 5, characterized in that: The cable suspension depth is determined to meet the following requirements: the minimum water depth of the reservoir minus 2 meters is less than the cable suspension depth, and the cable suspension depth is less than the minimum water depth of the reservoir; the electrode spacing is greater than the average thickness of the soil covering the membrane and less than the cable suspension depth.

7. The method for detecting the integrity of a geomembrane anti-seepage system during operation of a plain reservoir according to claim 5, wherein: The resistivity threshold range of the protective layer on the film is determined as follows: When the resistivity of the reservoir water is greater than the resistivity of the groundwater, the resistivity threshold range of the protective layer above the membrane is greater than the resistivity of the ground formation below the membrane and less than the resistivity of the reservoir water; When the resistivity of the reservoir water is lower than the resistivity of the groundwater, the resistivity threshold range of the protective layer above the membrane is higher than the resistivity of the reservoir water and lower than the resistivity of the ground layer below the membrane.

8. The method for detecting the integrity of a geomembrane anti-seepage system during operation of a plain reservoir according to claim 5, wherein: The calculation of the thickness of the protective layer on the film includes: identifying, in the resistivity profile, an area where the difference between the resistivity value and the reservoir water resistivity is less than a first threshold, and extracting the bottom boundary depth of the area; Identifying, in the resistivity profile, an area where the difference between the resistivity value and the resistivity of the sub-membrane formation is less than a second threshold, and extracting the top boundary depth of the area; The thickness of the protective layer on the film is obtained by subtracting the bottom boundary depth from the top boundary depth.

9. The method for detecting the integrity of a geomembrane anti-seepage system during operation of a plain reservoir according to claim 5, wherein: The division of the protective layer into too thick areas and too thin areas is based on the minimum thickness of the protective layer of the geomembrane anti-seepage system and the height of the check valve outlet from the geomembrane; The area on the film where the thickness of the protective layer is less than the minimum thickness is an area where the protective layer is too thin; The area on the film where the thickness of the protective layer is greater than the height is an area where the protective layer is too thick.

10. The method for detecting the integrity of a geomembrane anti-seepage system during operation of a plain reservoir according to claim 5, wherein: The method of dividing the geomembrane damaged area is: When the resistivity of the reservoir water is less than the resistivity of the groundwater, identifying an area in the resistivity profile where the resistivity value is less than the resistivity of the stratum beneath the membrane as a geomembrane damage area; When the resistivity of the reservoir water is greater than the resistivity of the groundwater, an area in the resistivity profile having a resistivity value greater than the resistivity of the stratum beneath the membrane is identified as a geomembrane damage area.

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