Resistivity extraction method and system based on single-pole spacing induced polarization sounding

Abstract

The application discloses a kind of resistivity extraction methods based on single pole distance induced polarization sounding, including obtaining the parameter information of single pole distance induced polarization sounding scheme;Arrangement power supply electrode;Determine the distribution of measuring point;In turn with each measuring point as center determine magnetic field observation direction;Power supply electrode is powered, corresponding magnetic field observation is carried out and observation signal is obtained;Iterative calculation obtains apparent resistivity and is combined with corresponding apparent depth, different depth resistivity information is obtained by inversion, completes the resistivity extraction based on single pole distance induced polarization sounding.The application also discloses a kind of system for realizing the resistivity extraction based on single pole distance induced polarization sounding of the application.By observing the horizontal magnetic field of induced electric field to extract the resistivity information of different depth, the time domain induced polarization sounding parameter is expanded, the detection effect can be improved, and the reliability is high, accurate.

Description

Technical Field

[0001] This invention belongs to the field of geophysical exploration, specifically relating to a resistivity extraction method and system based on single-pole induced polarization sounding. Background Technology

[0002] With economic and technological development and the improvement of people's living standards, geophysical exploration has received increasing attention. Time-domain induced polarization (TIP) is an important detection method in geophysical exploration, mainly used for exploring sulfide deposits, finding groundwater, and detecting karst formations.

[0003] Traditional time-domain induced polarization (IPC) theory posits that after the current supplied to the ground is turned off, an early electromagnetic induction field emerges, followed by an induced electric field. Furthermore, the electromagnetic induction field introduces noise interference into the observation of the induced electric field. Therefore, chopping is typically employed in IPC to eliminate the early electromagnetic induction field. In practice, the electric field response measured using grounded electrodes after a period of current supply to the ground and subsequent current cut-off primarily reflects the induced electric field information. Conversely, the magnetic field response obtained using an ungrounded induction coil primarily reflects the induced electromagnetic field information. The charge rate information can be extracted from the time-decreasing electric field signal, while the resistivity information can be extracted from the time-decreasing magnetic field signal.

[0004] Traditional induced polarization (IP) sounding obtains resistivity and polarizability information at different depths by observing the electric field at a series of different electrode spacings. In 2022, researchers proposed that time-domain IPI, after power-off, reveals IPI information at different depths by observing the electric field decay curve over time. This means that different delayed IPI fields after power-off can reflect IPI information at different depths. Based on this, a single-gap IPI sounding method was proposed, which obtains charge rate information at different depths by observing the time-varying electric field. However, this scheme does not address how to obtain resistivity information at different depths. This limits its practical application prospects. Summary of the Invention

[0005] One of the objectives of this invention is to provide a resistivity extraction method based on single-pole induced polarization (SIP) that can acquire resistivity information at different depths with high reliability and accuracy.

[0006] The second objective of this invention is to provide a system for implementing the resistivity extraction method based on single-pole induced polarization sounding.

[0007] The resistivity extraction method based on single-pole induced polarization sounding provided by this invention includes the following steps:

[0008] S1. Obtain parameter information for the single-pole-gap induced polarization sounding scheme;

[0009] S2. Arrange the power supply electrodes according to the parameter information obtained in step S1;

[0010] S3. Determine the distribution of measuring points based on the arrangement of the power supply electrodes;

[0011] S4. Determine the direction of magnetic field observation by taking each measuring point as the center;

[0012] S5. Power the power supply electrodes, observe the corresponding magnetic field, and acquire the observation signal;

[0013] S6. Based on the observation signal obtained in step S5, the apparent resistivity is calculated iteratively, and combined with the corresponding apparent depth, the resistivity information at different depths is obtained through inversion, thus completing the resistivity extraction based on single-pole induced polarization sounding.

[0014] Step S2, which involves arranging the power supply electrodes based on the parameter information obtained in step S1, specifically includes the following steps:

[0015] Based on the distribution range of the measuring lines and points and the maximum depth to be measured, power supply electrodes are arranged; the electrode spacing 2L is at least 4 times the maximum detection depth D; the power supply lines are arranged in a U-shape.

[0016] Step S3, which involves determining the distribution of measuring points based on the arrangement of the power supply electrodes, specifically includes the following steps:

[0017] The measuring points are distributed in the middle 1 / 3 of the distance between the power supply electrodes and the two sides of the distance between the power supply electrodes.

[0018] Step S4, which involves determining the magnetic field observation direction centered on each measuring point, specifically includes the following steps:

[0019] Centered on the measuring point, observe the axial magnetic field Bx and the radial magnetic field By; where the axial direction is defined as parallel to the line source direction and the radial direction is defined as perpendicular to the line source direction.

[0020] Step S5, which involves supplying power to the power supply electrodes, performing corresponding magnetic field observations, and acquiring observation signals, specifically includes the following steps:

[0021] A bipolar square wave is injected into the power supply electrode line, the receiver and transmitter are synchronized, and the magnetic field signal is observed throughout the process.

[0022] Step S6 involves iteratively calculating the apparent resistivity based on the observation signal obtained in step S5, and combining it with the corresponding apparent depth to obtain resistivity information at different depths through inversion, thus completing the resistivity extraction based on single-pole induced polarization sounding. Specifically, this includes the following steps:

[0023] The ground is assumed to be a horizontal, uniform half-space with a resistivity of ρ and a permeability of μ. The distance between the supply electrodes is 2L, the supply current is I, and the supply electrodes are located at positions A and B.

[0024] Establish a horizontal rectangular coordinate system with the center of line AB as the origin and line AB as the x-axis. The relationship between the magnetic field and resistivity at any point (x, y, z) is expressed as:

[0025]

[0026]

[0027] In the formula, R is the first intermediate variable and R = [(x - x')] 2 +y 2 ] 1 / 2 x' is the x-coordinate of the source integration unit point; r TE The reflection coefficient is and λ is the integral variable of the Bessel function, u1 is the second intermediate variable and u1 = (λ) 2 +iωμσ) 1 / 2 , i is the imaginary unit, ω is the angular frequency, σ is the third intermediate variable and σ=1 / ρ; J1() is the first-order Bessel function; Let R1 be the upper and lower limits of integration; R1 is the fourth intermediate variable and R1 = [(x+L)]. 2 +y 2 ] 1 / 2 R2 is the fifth intermediate variable and R2 = [(xL)] 2 +y 2 ] 1 / 2 J0() is the zeroth-order Bessel function;

[0028] The magnetic field data B is filtered using a numerical filtering algorithm. x and B y By converting to the time domain, we obtain the magnetic field data B, which decays over time after the current is turned off. x (ρ,t) and B y (ρ,t), and then the apparent resistivity ρ corresponding to different times is obtained through iterative calculation. s (t), and finally combined with the apparent depth d corresponding to different times. s (t), and the resistivity distribution information at different depths is obtained by inversion;

[0029] Wherein, the apparent depth d s The formula for calculating (t) is: D is the maximum detectable depth related to the electrode distance 2L and D = 2L / N, N is a positive integer and N∈[4,10], t is the delay corresponding to the turn-off start time of 0, and T on This refers to the duration of the supply current.

[0030] This invention also provides a system for implementing the resistivity extraction method based on single-pole induced polarization sounding, comprising a data acquisition module, an electrode arrangement module, a measurement point distribution module, a direction determination module, a magnetic field observation module, and a resistivity extraction module; the data acquisition module, electrode arrangement module, measurement point distribution module, direction determination module, magnetic field observation module, and resistivity extraction module are connected in series; the data acquisition module is used to acquire parameter information of the single-pole induced polarization sounding scheme and upload the data information to the electrode arrangement module; the electrode arrangement module is used to arrange the power supply electrodes according to the received data information and upload the data information to the measurement point distribution module; the measurement point distribution module is used to arrange the power supply electrodes according to the received data information and upload the data information to the measurement point distribution module; the measurement point distribution module is used to arrange the power supply electrodes according to the received data information and the direction determination module. The electrode placement determines the distribution of measurement points, and the data is uploaded to the direction determination module. The direction determination module, based on the received data, sequentially determines the magnetic field observation direction centered on each measurement point and uploads the data to the magnetic field observation module. The magnetic field observation module, based on the received data, supplies power to the electrode, performs corresponding magnetic field observations, acquires the observation signals, and uploads the data to the resistivity extraction module. The resistivity extraction module, based on the received data and the observation signals, iteratively calculates the apparent resistivity and, combined with the corresponding apparent depth, obtains resistivity information at different depths through inversion, thus completing the resistivity extraction based on single-pole induced polarization depth sounding.

[0031] The resistivity extraction method and system based on single-pole induced polarization sounding provided by this invention extracts resistivity information at different depths by observing the horizontal magnetic field induced by the induced polarization field. This expands the time-domain induced polarization sounding parameters, improves the detection effect, and has high reliability and accuracy. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the method flow of the present invention.

[0033] Figure 2 This is a schematic diagram of the observation range in the method of the present invention.

[0034] Figure 3 This is a schematic diagram of the observed magnetic field in the method of the present invention.

[0035] Figure 4 This is a schematic diagram of the functional modules of the system of the present invention. Detailed Implementation

[0036] like Figure 1 The diagram shown is a flowchart of the method of the present invention: The resistivity extraction method based on single-pole induced polarization sounding disclosed in this invention includes the following steps:

[0037] S1. Obtain parameter information for the single-pole-gap induced polarization sounding scheme;

[0038] S2. Based on the parameter information obtained in step S1, arrange the power supply electrodes; specifically including the following steps:

[0039] Based on the distribution range of the measuring lines and points and the maximum depth to be measured, power supply electrodes are arranged; the electrode spacing 2L is at least 4 times the maximum detection depth D; the power supply lines are arranged in a U-shape.

[0040] S3. Determine the distribution of measuring points based on the location of the power supply electrodes; this includes the following steps:

[0041] The measuring points are distributed in the middle 1 / 3 of the distance between the power supply electrodes and the two side 1 / 3 of the distance between the power supply electrodes;

[0042] Specific scope such as Figure 2 As shown, Figure 2 The dashed box and its inner area in the diagram represent the final observation range.

[0043] S4. Determine the direction of magnetic field observation sequentially, centering on each measuring point; this includes the following steps:

[0044] With the measuring point as the center, observe the axial magnetic field Bx and the radial magnetic field By; where the axial direction is defined as parallel to the line source direction and the radial direction is defined as perpendicular to the line source direction.

[0045] S5. Power the electrodes, observe the corresponding magnetic field, and acquire the observation signal; specifically, this includes the following steps:

[0046] A bipolar square wave is injected into the power supply electrode line, the receiver and transmitter are synchronized, and the magnetic field signal is observed throughout the process;

[0047] S6. Based on the observation signal obtained in step S5, the apparent resistivity is calculated iteratively, and combined with the corresponding apparent depth, the resistivity information at different depths is obtained through inversion, thus completing the resistivity extraction based on single-pole induced polarization sounding; specifically including the following steps:

[0048] like Figure 3 The diagram shown is a schematic of the observed magnetic field.

[0049] The ground is assumed to be a horizontal, uniform half-space with a resistivity of ρ and a permeability of μ. The distance between the supply electrodes is 2L, the supply current is I, and the supply electrodes are located at positions A and B.

[0050] Establish a horizontal rectangular coordinate system with the center of line AB as the origin and line AB as the x-axis. The relationship between the magnetic field and resistivity at any point (x, y) is expressed as:

[0051]

[0052]

[0053] In the formula, R is the first intermediate variable and R = [(x - x')] 2 +y 2 ] 1 / 2 x' is the x-coordinate of the source integration unit point; r TE The reflection coefficient and λ is the integral variable of the Bessel function, u1 is the second intermediate variable and u1 = (λ) 2 +iωμσ) 1 / 2 , i is the imaginary unit, ω is the angular frequency, σ is the third intermediate variable and σ=1 / ρ; J1() is the first-order Bessel function; Let R1 be the upper and lower limits of integration; R1 is the fourth intermediate variable and R1 = [(x+L)]. 2 +y 2 ] 1 / 2 R2 is the fifth intermediate variable and R2 = [(xL)] 2 +y 2 ] 1 / 2 J0() is the zeroth-order Bessel function;

[0054] The magnetic field data B is filtered using a numerical filtering algorithm. x and B y By converting to the time domain, we obtain the magnetic field data B, which decays over time after the current is turned off. x (ρ,t) and B y (ρ,t), and then the apparent resistivity ρ corresponding to different times is obtained through iterative calculation. s (t), and finally combined with the apparent depth d corresponding to different times. s (t), and the resistivity distribution information at different depths is obtained by inversion;

[0055] Wherein, the apparent depth d s The formula for calculating (t) is: D is the maximum detectable depth related to the electrode distance 2L and D = 2L / N, N is a positive integer and N∈[4,10], t is the delay corresponding to the turn-off start time of 0, and T on This refers to the duration of the supply current.

[0056] like Figure 4The diagram shows the functional modules of the system of the present invention: The system disclosed in this invention for implementing the resistivity extraction method based on single-pole induced polarization sounding includes a data acquisition module, an electrode arrangement module, a measurement point distribution module, a direction determination module, a magnetic field observation module, and a resistivity extraction module; these modules are connected in series. The data acquisition module acquires parameter information of the single-pole induced polarization sounding scheme and uploads the data information to the electrode arrangement module. The electrode arrangement module arranges the power supply electrodes according to the received data information and uploads the data information to the measurement point distribution module. The measurement point distribution module arranges the electrodes according to the received data information. The data information is processed as follows: Based on the arrangement of the power supply electrodes, the distribution of measurement points is determined, and the data is uploaded to the direction determination module. The direction determination module, based on the received data, sequentially determines the magnetic field observation direction centered on each measurement point and uploads the data to the magnetic field observation module. The magnetic field observation module, based on the received data, supplies power to the power supply electrodes, performs corresponding magnetic field observations, acquires the observation signals, and uploads the data to the resistivity extraction module. The resistivity extraction module, based on the received data and the observation signals, iteratively calculates the apparent resistivity and, combined with the corresponding apparent depth, obtains resistivity information at different depths through inversion, thus completing the resistivity extraction based on single-pole induced polarization depth sounding.

Claims

1. A resistivity extraction method based on single-pole induced polarization sounding, comprising the following steps: S1. Obtain parameter information for the single-pole-gap induced polarization sounding scheme; S2. Arrange the power supply electrodes according to the parameter information obtained in step S1; S3. Determine the distribution of measuring points based on the location of the power supply electrodes; S4. Determine the direction of magnetic field observation by taking each measuring point as the center; S5. Power the power supply electrodes, observe the corresponding magnetic field, and acquire the observation signal; S6. Based on the observation signal obtained in step S5, the apparent resistivity is calculated iteratively, and combined with the corresponding apparent depth, resistivity information at different depths is obtained through inversion, thus completing the resistivity extraction based on single-pole induced polarization sounding; specifically including the following steps: Assume the earth is a horizontal, uniform half-space with a resistivity of Magnetic permeability is The electrode distance is The supply current is The power supply electrodes are located at positions A and B; Establish a horizontal rectangular coordinate system with the center of line AB as the origin and line AB as the x-axis. Any point... The relationship between the magnetic field and resistivity at a given location is expressed as: In the formula The first intermediate variable and , The x-coordinate of the field source integration unit point; The reflection coefficient and , Let be the integral variable of the Bessel function. It is the second intermediate variable and , The imaginary unit, Angular frequency, It is the third intermediate variable and ; It is a first-order Bessel function; These are the upper and lower limits of the integral; It is the fourth intermediate variable and ; It is the fifth intermediate variable and ; It is a zero-order Bessel function; The magnetic field data is processed using a numerical filtering algorithm. and By converting to the time domain, we obtain the magnetic field data that decays over time after the current is turned off. and Then, the apparent resistivity at different times is obtained through iterative calculation. Finally, combining the apparent depth corresponding to different times The resistivity distribution information at different depths is obtained through inversion. in, View Depth The calculation formula is , To the distance from the supply electrode The relevant maximum detectable depth and , are positive integers and , This is the delay corresponding to the start time of shutdown being 0. This refers to the duration of the supply current.

2. The resistivity extraction method based on single-pole induced polarization sounding according to claim 1, characterized in that... Step S2, which involves arranging the power supply electrodes based on the parameter information obtained in step S1, specifically includes the following steps: Based on the distribution range of the survey lines and points, and the maximum depth to be measured, power supply electrodes are arranged; electrode spacing... At least the maximum detection depth Four times that of the previous year; the power supply lines are arranged in a U-shape.

3. The resistivity extraction method based on single-pole induced polarization sounding according to claim 2, characterized in that... Step S3, which involves determining the distribution of measuring points based on the arrangement of the power supply electrodes, specifically includes the following steps: The measuring points are distributed in the middle 1 / 3 of the distance between the power supply electrodes and the two sides of the distance between the power supply electrodes.

4. The resistivity extraction method based on single-pole induced polarization sounding according to claim 3, characterized in that... Step S4, which involves determining the magnetic field observation direction centered on each measuring point, specifically includes the following steps: Observe the axial magnetic field with the measuring point as the center. and radial magnetic field Wherein, the axial direction is defined as parallel to the direction of the line source, and the radial direction is defined as perpendicular to the direction of the line source.

5. The resistivity extraction method based on single-pole induced polarization sounding according to claim 4, characterized in that... Step S5, which involves supplying power to the power supply electrodes, performing corresponding magnetic field observations, and acquiring observation signals, specifically includes the following steps: A bipolar square wave is injected into the power supply electrode line, the receiver and transmitter are synchronized, and the magnetic field signal is observed throughout the process.

6. A system for implementing the resistivity extraction method based on single-pole induced polarization sounding as described in any one of claims 1 to 5, characterized in that... It includes a data acquisition module, an electrode arrangement module, a measuring point distribution module, a direction determination module, a magnetic field observation module, and a resistivity extraction module; these modules are connected in series. The data acquisition module acquires the parameter information of the single-pole induced polarization sounding scheme and uploads the data to the electrode arrangement module. The electrode arrangement module arranges the power supply electrodes according to the received data and uploads the data to the measuring point distribution module. The measurement point distribution module is used to determine the distribution of measurement points based on the received data information and the arrangement position of the power supply electrodes, and then upload the data information to the direction determination module. The direction determination module is used to determine the magnetic field observation direction with each measuring point as the center based on the received data information, and then upload the data information to the magnetic field observation module. The magnetic field observation module is used to supply power to the power supply electrodes based on the received data information, conduct corresponding magnetic field observations, acquire observation signals, and upload the data information to the resistivity extraction module. The resistivity extraction module is used to iteratively calculate the apparent resistivity based on the received data information and observation signals, and combine it with the corresponding apparent depth to obtain resistivity information at different depths through inversion, thus completing the resistivity extraction based on single-pole induced polarization depth sounding.

Images