A method of induced polarization depth sounding based on single pole distance

Abstract

The present invention discloses a method for induced polarization sounding based on a single-pole spacing, including determining a region to be sounded; performing sounding observations on the region to be sounded to obtain sounding observation data; calculating a charging rate decay curve; obtaining the charging rate decay curves of all measuring points and calculating a background charging rate decay curve; calculating a ratio curve of the charging rate decay curve of each measuring point to the background charging rate decay curve; calculating a relative ratio curve of each measuring point; calculating the relative ratio of charging rates corresponding to different depths at different times, and completing the final single-pole spacing induced polarization sounding. The present invention can obtain induced polarization information of different depths by observing with a long supply electrode spacing. Compared with the traditional geometric sounding method that uses multiple supply electrode spacings of different lengths to achieve sounding, the method of the present invention greatly improves the field work efficiency of induced polarization sounding.

Description

Technical Field

[0001] The invention belongs to the field of geophysical exploration, and in particular relates to an induced polarization depth sounding method based on a single pole distance. Background Art

[0002] With the development of economy and technology, geophysical exploration has attracted more and more attention. Induced polarization sounding is an important detection method in the field of geophysical exploration, mainly used for exploring sulfide mines, finding groundwater and detecting karst.

[0003] The IP method is divided into profile measurement and IP sounding. The device for profile measurement is mainly a mid-step device, which is highly efficient, but can only obtain the total polarization rate at a certain depth, and has no sounding function. To obtain the polarization rate at different depths, it is necessary to change the length of the electrode spacing. The polarization rate measured by the electrode spacing with a small length reflects the geological information of the shallow part, while the polarization rate measured by the electrode spacing with a large length reflects the geological information of the deep part. This is the principle of IP sounding (also known as geometric IP sounding). Therefore, geometric IP sounding requires at least 10 electrode spacings ranging from a few meters to thousands of meters to complete the IP sounding work at a depth of 500 meters. In the working environment of mountainous areas with developed vegetation, data collection is time-consuming and laborious, which is not only costly but also extremely inefficient. Summary of the invention

[0004] The object of the present invention is to provide a single-pole-distance induced polarization sounding method which has high reliability, good accuracy and is simple and convenient to implement.

[0005] The monopolar-distance induced polarization sounding method provided by the present invention comprises the following steps:

[0006] S1. Determine the area to be measured;

[0007] S2. Conducting bathymetric observation in the area to be bathymetrically measured to obtain bathymetric observation data;

[0008] S3. Calculate the charging rate attenuation curve based on the depth observation data obtained in step S2;

[0009] S4. Obtain the charging rate decay curves of all measuring points and calculate the background charging rate decay curve;

[0010] S5. Calculate the ratio curve of the charging rate decay curve of each measuring point to the background charging rate decay curve;

[0011] S6. Calculate the relative ratio curve of each measuring point according to the ratio curve obtained in step S5;

[0012] S7. According to the relative ratio curves of each measuring point obtained in step S6, the relative ratios of the charging rates corresponding to different depths at different times are calculated to complete the final single-pole-distance induced polarization depth measurement.

[0013] The step S2 of performing a bathymetric observation on the area to be bathymetrically measured to obtain bathymetric observation data specifically includes the following steps:

[0014] The observation is carried out using a mid-ladder device; the electrode spacing of the mid-ladder device is set to N times the maximum sounding depth, where N is the set multiple and the value range is N∈[4,10];

[0015] Observe the main axis section of the mid-ladder device and the side section parallel to the main axis;

[0016] During observation, only one power supply electrode is arranged to realize the observation of depth sounding data at several measuring points; the power supply emits a bipolar square wave with a duty cycle of 50%, and the curve Ut of the decay of the induced polarization secondary field with time is observed during the intermittent period after power failure. The voltage value before shutdown is U0, and the start time of shutdown is 0. The different delays t are observed. i The corresponding voltage value U i , thus obtaining the bathymetric observation data.

[0017] Step S3, based on the depth measurement observation data obtained in step S2, calculates the charging rate attenuation curve, specifically, calculates the charging rate attenuation curve Mt; point t on the curve i The corresponding charging rate M i for

[0018] Step S4 is to obtain the charging rate attenuation curves of all measuring points and calculate the background charging rate attenuation curve, specifically, to obtain the charging rate attenuation curves of all measuring points and calculate the charging rate attenuation curves of all measuring points at point t. i The charging rate M i The average value M ai , thus obtaining the background charging rate decay curve M a -t.

[0019] Step S5 is to calculate the ratio curve of the charging rate attenuation curve of each measuring point to the background charging rate attenuation curve, specifically, to calculate the ratio curve of the charging rate attenuation curve of each measuring point at point t i The charging rate M i The background charging rate decay curve at t i Background charge rate M ai The ratio R i , thus obtaining the ratio curve Rt.

[0020] Step S6 calculates the relative ratio curve of each measuring point based on the ratio curve obtained in step S5, specifically, the ratio curve of each measuring point obtained in step S6 is subtracted from the minimum value of the ratio curve of the measuring point itself, so as to obtain the relative ratio curve R of each measuring point. c -t.

[0021] According to the relative ratio curve of each measuring point obtained in step S6, the relative ratio of the charging rate corresponding to different depths at different times is calculated in step S7 to complete the final single-pole-distance induced polarization depth measurement, specifically, according to the relative ratio curve of each measuring point obtained in step S6, the relative ratio of the charging rate corresponding to different depths at different times is calculated to obtain the depth measurement curve Rc-H; specifically, it includes the following steps:

[0022] The time-division depth method is used to calculate the different time t i The corresponding apparent depth:

[0023] The maximum depth H is determined by the electrode spacing AB, and N is a set multiple, and its value range is N∈[4,10];

[0024] Different time t i The corresponding visual depth H i for T = power supply time = power off time;

[0025] Repeat steps S6 and S7 to obtain the depth measurement curves Rc-H at different depths.

[0026] The single-pole-spacing induced polarization sounding method provided by the present invention proposes that the attenuation curve of time-domain induced polarization observed with time delay after power failure already contains induced polarization information at different depths, that is, the secondary fields at different times reflect induced polarization information at different depths. Therefore, the present invention can obtain induced polarization information at different depths by observing a long supply electrode spacing. Compared with the traditional geometric sounding method that uses multiple supply electrode spacings of different lengths to achieve sounding, the method of the present invention has high reliability, good accuracy and is simple and convenient to implement. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The figure is a schematic diagram of the method flow of the present invention.

[0028] Figure 2 Schematic diagram of the voltage decay curve of the method of the present invention.

[0029] Figure 3 Schematic diagram of the charging rate decay curve of the method of the present invention.

[0030] Figure 4 The figure is a schematic diagram of a curve showing the change of charging rate over time at 21 measuring points in an embodiment of the method of the present invention.

[0031] Figure 5 It is a schematic diagram of a curve showing the change of the average charging rate of 5 measuring points and all measuring points over time in an embodiment of the method of the present invention.

[0032] Figure 6The figure is a schematic diagram of a curve showing the charging rate ratio R changing with time in an embodiment of the method of the present invention.

[0033] Figure 7 is the relative ratio R of the charging rate curve of the embodiment of the method of the present invention c Schematic diagram of the curve changing with time.

[0034] Figure 8 is the charging rate ratio R of the embodiment of the method of the present invention c Schematic diagram of the curve changing with depth. DETAILED DESCRIPTION

[0035] like Figure 1 The method flow chart of the method of the present invention is shown as follows: the single-pole-distance induced polarization sounding method provided by the present invention comprises the following steps:

[0036] S1. Determine the area to be measured;

[0037] S2. Performing bathymetric observation in the area to be bathymetrically measured to obtain bathymetric observation data; specifically comprising the following steps:

[0038] The observation is carried out using a mid-ladder device; the electrode spacing of the mid-ladder device is set to N times the maximum sounding depth, where N is the set multiple and the value range is N∈[4,10];

[0039] Observe the main axis section of the mid-ladder device and the side section parallel to the main axis;

[0040] During observation, only one power supply electrode is arranged to realize the observation of depth sounding data at several measuring points; the power supply emits a bipolar square wave with a duty cycle of 50%, and the curve Ut of the decay of the induced polarization secondary field with time is observed during the intermittent period after power failure. The voltage value before shutdown is U0, and the start time of shutdown is 0. The different delays t are observed. i The corresponding voltage value U i , thus obtaining the bathymetric observation data;

[0041] S3. Calculate the charging rate attenuation curve based on the depth observation data obtained in step S2; specifically, calculate the charging rate attenuation curve Mt; point t on the curve i The corresponding charging rate M i for

[0042] S4. Obtain the charging rate decay curves of all measuring points and calculate the background charging rate decay curve; specifically, obtain the charging rate decay curves of all measuring points and calculate the charging rate decay curves of all measuring points at point t i The charging rate M i The average value M ai , thus obtaining the background charging rate decay curve M a -t;

[0043] S5. Calculate the ratio curve of the charging rate decay curve of each measuring point to the background charging rate decay curve; specifically, calculate the ratio of each measuring point at point t i The charging rate M i The background charging rate decay curve at t i Background charge rate M ai The ratio R i , thus obtaining the ratio curve Rt;

[0044] S6. Calculate the relative ratio curve of each measuring point according to the ratio curve obtained in step S5; specifically, subtract the minimum value of the ratio curve of each measuring point obtained in step S6 from the ratio curve of each measuring point, thereby obtaining the relative ratio curve R of each measuring point. c -t;

[0045] S7. According to the relative ratio curve of each measuring point obtained in step S6, the relative ratio of the charging rate corresponding to different depths at different times is calculated to complete the final single-pole-distance induced polarization depth measurement. Specifically, according to the relative ratio curve of each measuring point obtained in step S6, the relative ratio of the charging rate corresponding to different depths at different times is calculated to obtain the depth measurement curve Rc-H; specifically, it includes the following steps:

[0046] The time-division depth method is used to calculate the different time t i The corresponding apparent depth:

[0047] The maximum depth H is determined by the electrode spacing AB, and N is a set multiple, and its value range is N∈[4,10];

[0048] Different time t i The corresponding visual depth H i for T = power supply time = power off time;

[0049] Repeat steps S6 and S7 to obtain the depth measurement curves Rc-H, H at different depths. i Corresponding relative electrostatic intensity R ci .

[0050] The method of the present invention is further described below in conjunction with an embodiment:

[0051] A certain survey area requires a maximum induced polarization depth of 400m, using a supply electrode spacing AB = 2000m, a survey line length of 800m, a point spacing of 40m, and a total of 21 survey points; the processing results according to the above invention steps are as follows: N = 5 in the depth calculation process;

[0052] Figure 4 The charging rate attenuation curves of 21 measuring points show how the charging rates at different measuring points change with the delay. Figure 5 The figure is a schematic diagram of the average charging rate attenuation curve of 5 measuring points and 21 measuring points, which shows the comparison between the delayed change of charging rate at different measuring points and the delayed change of background charging rate; Figure 6 It is a curve diagram of the charging rate ratio of 5 measuring points over time, indicating that the ratio of the charging rate of different measuring points to the background changes with the delay; Figure 7 It is a curve diagram of the relative ratio Rc of the five measuring points over time, indicating the relative ratio of the ratio of the charging rate of different measuring points to the background after returning to 0 with the minimum value; Figure 8 is the relative ratio R of the five measuring points c The curve graph of changes with depth reflects the relative charging rate at different depths, representing the differences in induced polarization effects at different depths.

[0053] The traditional induced polarization sounding theory is based on geometric sounding, that is, different lengths of electrode spacing correspond to different depths to produce induced polarization effect. Therefore, a group of different electrode spacings from small to large are required for power supply and observation respectively to obtain induced polarization information at different depths. For example, the maximum sounding depth is required to be 400m, and a sounding data is required every 40m from shallow to deep (depth 40m, 80m, 120m, 160m, 200m, 240m, 280m, 320m, 360m, 400m). If the relationship between the electrode spacing and the depth is H=AB / 5, then for each measuring point, it is necessary to implement observations of electrode spacings AB of 200m, 400m, 600m, 800m, 1000m, 1200m, 1400m, 1600m, 1800m, and 2000m in turn.

[0054] The theory of single-pole-spacing IP sounding is based on the fact that the attenuation curve obtained by time-domain IP sounding observations already contains IP information at different depths, that is, different delays correspond to different depths. Therefore, for example, if the maximum sounding depth is 400m, a sounding data is required every 40m from shallow to deep. If the relationship between the power supply electrode spacing and the depth is H=AB / 5, then the maximum power supply electrode spacing AB=2000m, then only the attenuation data of the pole spacing of 2000m is required, the power supply delay and power-off observation delay are 2s, and a data is extracted every 200ms delay, that is, the information corresponding to the 40m incremental depth.

[0055] Compared with the prior art, the method of the present invention has the advantage that by using time-domain induced polarization sounding with a single larger supply electrode spacing, induced polarization difference information at different depths can be obtained, which greatly improves the field work efficiency of induced polarization sounding.

Claims

1. A method for induced polarization sounding based on a single pole distance, comprising the following steps: S1. Determine the area to be measured; S2. Conducting bathymetric observation in the area to be bathymetrically measured to obtain bathymetric observation data; S3. Calculate the charging rate attenuation curve based on the depth observation data obtained in step S2; S4. Obtain the charging rate decay curves of all measuring points and calculate the background charging rate decay curve; specifically, obtain the charging rate decay curves of all measuring points and calculate the charging rate decay curves of all measuring points at point t i The charging rate M i The average value M ai , thus obtaining the background charging rate decay curve M a -t; S5. Calculate the ratio curve of the charging rate decay curve of each measuring point to the background charging rate decay curve; S6. Calculate the relative ratio curve of each measuring point according to the ratio curve obtained in step S5; subtract the minimum value of the ratio curve of each measuring point obtained in step S5 from the ratio curve of each measuring point, thereby obtaining the relative ratio curve R of each measuring point. c -t; S7. According to the relative ratio curves of each measuring point obtained in step S6, the relative ratios of the charging rates corresponding to different depths at different times are calculated to complete the final single-pole-distance induced polarization depth measurement.

2. The method for induced polarization sounding based on a single-pole distance according to claim 1, characterized in that The step S2 of performing a bathymetric observation on the area to be bathymetrically measured to obtain bathymetric observation data specifically includes the following steps: The observation is carried out using a mid-ladder device; the electrode spacing of the mid-ladder device is set to N times the maximum sounding depth, where N is the set multiple and the value range is N∈[4,10]; Observe the main axis section of the mid-ladder device and the side section parallel to the main axis; During observation, only one power supply electrode is arranged to realize the observation of depth sounding data of several measuring points; the power supply emits a bipolar square wave with a duty cycle of 50%, and the curve Ut of the decay of the induced polarization secondary field with time is observed during the intermittent period after power failure. The voltage value before shutdown is U0, and the start time of shutdown is 0. The different delays t are observed. i The corresponding voltage value U i , thus obtaining the bathymetric observation data.

3. The method for induced polarization sounding based on a single-pole pitch according to claim 2, characterized in that Step S3, based on the depth measurement observation data obtained in step S2, calculates the charging rate attenuation curve, specifically, calculates the charging rate attenuation curve Mt; point t on the curve i The corresponding charging rate M i for 4. The method for induced polarization sounding based on a single-pole distance according to claim 3, characterized in that Step S5 is to calculate the ratio curve of the charging rate attenuation curve of each measuring point to the background charging rate attenuation curve, specifically, to calculate the ratio curve of the charging rate attenuation curve of each measuring point at point t i The charging rate M i The background charging rate decay curve at t i Background charge rate M ai The ratio R i , thus obtaining the ratio curve Rt.

5. The method for induced polarization sounding based on a single-pole distance according to claim 4, characterized in that According to the relative ratio curve of each measuring point obtained in step S6, the relative ratio of the charging rate corresponding to different depths at different times is calculated in step S7 to complete the final single-pole-distance induced polarization depth measurement, specifically, according to the relative ratio curve of each measuring point obtained in step S6, the relative ratio of the charging rate corresponding to different depths at different times is calculated to obtain the depth measurement curve Rc-H; specifically, it includes the following steps: The time-division depth method is used to calculate the different time t i The corresponding apparent depth: The maximum depth H is determined by the electrode spacing AB, and N is the set multiple, and N≥5; Different time t i The corresponding visual depth H i for T = power supply time = power off time; Repeat steps S6 and S7 to obtain the depth measurement curves Rc-H at different depths.

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