A spectrum analysis method to improve the accuracy of calculating nuclide content

Abstract

The present invention provides a spectrum decomposition method for improving the accuracy of calculating nuclide content, comprising the steps of: a. calculating airborne gamma spectrum correction parameters using calibration data; b. performing aircraft background correction, cosmic ray correction, atmospheric radon correction, and altitude correction on the airborne gamma spectrum data after noise reduction in the survey area using the airborne gamma spectrum correction parameters; c. calculating the number of measuring points used for spectrum decomposition according to the flight altitude and the counting rate; d. performing weighted averaging on the number of measuring points used for spectrum decomposition to obtain the spectrum decomposition spectrum data of the spectrum decomposition measuring points; e. performing spectrum decomposition on the spectrum decomposition spectrum data of the spectrum decomposition measuring points using the unit spectrum obtained by calibration. The present invention not only reduces noise and increases accuracy, but also does not affect the abnormal amplitude, does not affect the subsequent abnormal screening and interpretation, and improves the effect of airborne geophysical data processing. The present invention is mainly used in airborne geophysical exploration, mineral exploration for metal mines, oil and gas, and radioactive minerals, and can also be applied to tasks such as emergency aviation monitoring of nuclear without crystal measurement, nuclear anti-terrorism, airborne geophysical exploration, and environmental monitoring.

Description

Technical Field

[0001] The invention relates to a spectrum decomposition method, in particular to a spectrum decomposition method for improving the accuracy of calculating nuclide content. Background Art

[0002] Airborne geophysical prospecting is an aerogeophysical exploration technology that integrates a variety of new technologies. It is efficient, fast and economical. The main aerogeophysical prospecting methods include aeromagnetic survey, aeroradioactive survey, aerogravimetric survey and aeroelectromagnetic survey. At the beginning, aerogeophysical prospecting was mainly aeromagnetic survey and aeroradioactive survey, which were used to find mineral resources such as magnetic deposits, radioactive deposits and oil and gas fields. Later, it was gradually expanded to the fields of geological mapping, tectonic research, radioactive environment measurement and nuclear accident emergency monitoring.

[0003] In the processing of the full spectrum data of airborne gamma spectroscopy, since each data is used, the counting cycle of airborne gamma measurement is 1 second, so the counting rate is generally low, and the accuracy of calculating the nuclide content depends on the counting rate used. Therefore, in order to improve the accuracy of calculating the nuclide content, the counting rate used must be increased. The method to increase the counting rate is either to increase the volume of the crystal used for measurement or to accumulate the counting rate of the measurement points (sacrificing geometric resolution). Under the condition that the hardware facilities of airborne gamma spectroscopy remain unchanged, only the latter can be used. The traditional processing method is 5-point (7-point, 9-point) weighted sliding average. This method can increase the accuracy of calculating the nuclide content in the background area, but it reduces the amplitude of the anomaly in the abnormal area, and even the anomaly will be annihilated. And this weighted sliding average of fixed points is not reasonable in the physical sense.

[0004] Therefore, there is an urgent need for a method to process airborne geophysical data, which can effectively increase the accuracy of calculated nuclides while retaining abnormal peaks, so as to achieve the results of reducing noise and not reducing abnormal peaks. Summary of the invention

[0005] The purpose of the present invention is to provide a spectrum analysis method for improving the accuracy of calculating the nuclide content, so as to solve the current problem that it is impossible to simultaneously reduce noise and not reduce abnormal peaks.

[0006] The present invention is achieved in that:

[0007] A spectrum analysis method for improving the accuracy of calculating nuclide content includes the following steps.

[0008] a. Calculate aviation gamma full spectrum correction parameters using calibration data;

[0009] b. Use the aviation gamma spectrum correction parameters to perform aircraft background correction, cosmic ray correction, atmospheric radon correction, and altitude correction on the aviation gamma spectrum data after noise reduction in the survey area;

[0010] c. Calculate the number of measurement points used for spectrum analysis based on the flight altitude, flight speed and the nuclide window count rate. The calculation method is:

[0011]

[0012] Where n is the number of measurement points used for spectrum analysis; m is the window count rate of the measurement point for the calculated nuclide; M is the mean window count rate of the calculated nuclide in the whole area; δ is the mean square error of the window count rate of the calculated nuclide in the whole area; h is the flight altitude above the ground (m); v is the flight speed (km / h); and y is rounded down.

[0013] d. Perform weighted averaging on the measurement point data used for spectrum analysis to obtain spectrum analysis data of the spectrum analysis measurement points; weight calculation method:

[0014]

[0015] In the formula, ω i is the weight of the i-th point, n is the number of measurement points used for spectrum analysis; i is the serial number of the measurement points used for spectrum analysis, where the spectrum analysis point is the middle point and the others are arranged in the order of measurement points. For example, for 5-point spectrum analysis, the third point is the spectrum analysis point, and its front and back adjacent points are the second and fourth points respectively. The first point is pushed forward by one point from the front adjacent point, and the fifth point is pushed backward by one point from the back adjacent point, and so on.

[0016] e. Use the calibrated unit spectrum to deconstruct the deconstructed spectrum data of the deconstructed measurement points.

[0017] For the spectrum interpretation method for improving the accuracy of calculating nuclide content of the present application, in step a, the aviation gamma full spectrum correction parameters calculated using calibration data are all full spectrum.

[0018] For the spectrum decomposition method for improving the accuracy of calculating nuclide content of the present application, in step b, background correction, cosmic ray correction, atmospheric radon correction, and altitude correction are all full spectrum corrections.

[0019] For the spectrum decomposition method for improving the accuracy of calculating nuclide content of the present application, in step d, when the spectrum decomposition measuring point is located at the end point of the measuring line, single-side measuring point weighting is adopted.

[0020] The method of the present invention can be called "adaptive multi-point weighted spectrum decomposition method". The "adaptive" in the method includes two aspects of "adaptive". One is to calculate the weighted average points according to the flight height and speed of the measurement data, and the other is to calculate the weighted average points according to the size of the measurement point count value. The formula provided by the present invention can not only calculate the weighted average points, but also calculate the weight of each measurement point.

[0021] The present invention can quickly and effectively remove noise while retaining abnormal information, thus improving the effect of airborne geophysical data processing. The present invention is mainly used in airborne geophysical exploration, mineral exploration for metal ores, oil and gas, and radioactive minerals, and can also be applied to tasks such as nuclear emergency aviation monitoring, nuclear counter-terrorism, airborne geophysical exploration, and environmental monitoring. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a schematic diagram of the measurement area represented by each aerial survey point when the aerial survey flight altitude is 60m and the speed is 216km / h.

[0023] Figure 2 This is a schematic diagram of the measurement area represented by each aerial survey point when the aerial survey flight altitude is 120m and the speed is 216km / h.

[0024] Figure 3 It is a flow chart of the method of the present invention.

[0025] Figure 4 It is a cross-sectional plane diagram of a certain nuclide content obtained by the method of the present invention.

[0026] Figure 5 It is a cross-sectional plane diagram of a certain nuclide content obtained using the current method. DETAILED DESCRIPTION

[0027] The measurement area represented by each aerial survey point when the simulated aerial survey flight altitude is 60m and the speed is 216km / h, such as Figure 1 As shown in the figure, the measurement area represented by each aerial survey point when the simulated aerial survey flight altitude is 120m and the speed is 216km / h, as shown in the figure Figure 2 shown.

[0028] exist Figure 1 and Figure 2 In the figure, the blue box represents the measurement area of ​​the spectrum resolution point, and the boxes of other colors represent the measurement areas of adjacent measurement points. Figure 1 It can be seen that when the aerial survey flight altitude is 60m, the area measured by the spectrum analysis point overlaps the areas of two measurement points before and after, a total of four measurement points. The counts of the four points before and after repeatedly record part of the information of this measurement point. The size of the repeated area can be used as a weight to calculate all the counting information of this measurement point. Figure 2 When the aerial survey flight altitude is 120m, each measuring point contains information of a total of 9 measuring points before and after it. Because the flight altitude and flight speed determine the number of measuring points before and after each measuring point, the number of weighted sliding average points is designed to be the number of weighted average points calculated according to the flight altitude and flight speed of the measurement data, so as to make the result more reasonable.

[0029] Since the physical meaning of multi-point weighted averaging is to increase the counting rate and thus increase the accuracy, but this method will inevitably lose geometric resolution. When the counting value is high enough, the benefits brought by this treatment are less than the losses (multi-point weighted averaging will inevitably reduce the counting value of individual measuring points, making the originally very obvious abnormalities less obvious). Therefore, when the counting rate is high enough, the benefits will be greater if this treatment is not performed. In view of this situation, the present invention designs a conditional judgment option, that is, whether to weight the average of the previous and next measuring points is determined according to the value of the counting rate. When the nuclide counting rate is low, the adjacent measuring points are weighted and the spectrum is decomposed to improve the calculation accuracy of each nuclide content. When the nuclide counting rate is high (the calculation accuracy of the nuclide content itself is already high), the weighted sliding average is not performed; the purpose of reducing noise and not reducing abnormal peaks is achieved to the greatest extent.

[0030] like Figure 3 As shown, the spectrum decomposition method for improving the accuracy of calculating nuclide content provided by the present invention includes the following steps.

[0031] a. Calculate the aviation gamma full spectrum correction parameters using the calibration data.

[0032] The calculated aviation gamma spectrum correction parameters include aircraft background spectrum correction parameters, cosmic ray spectrum correction parameters, atmospheric radon spectrum correction parameters, altitude spectrum correction parameters and unit spectrum of each nuclide. Generally, they are calculated through altitude aviation gamma spectrum measurement data, dynamic band aviation gamma spectrum measurement data and aviation model spectrum measurement data.

[0033] b. Use the aviation gamma spectrum correction parameters to perform aircraft background correction, cosmic ray correction, atmospheric radon correction, and altitude correction on the aviation gamma spectrum data after noise reduction in the survey area.

[0034] The full spectrum correction parameters of the aviation gamma ray spectrum calculated in step a are used to perform full spectrum background correction, full spectrum cosmic ray correction, full spectrum atmospheric radon correction, and full spectrum height correction on the measured data, and the spectrum data is subjected to noise reduction before correction. The full spectrum height correction is performed using the method of ZL 202210497264.7, and the full spectrum atmospheric radon correction is performed using the methods of ZL202111079321.1, ZL 201911310746.1 or other proven effective methods.

[0035] c. Calculate the number of measurement points used for spectrum analysis based on the flight altitude, flight speed and the nuclide window count rate. The calculation method is as follows:

[0036]

[0037] Where n is the number of measurement points used for spectrum analysis; m is the window count rate of the measurement point for the calculated nuclide; M is the mean window count rate of the calculated nuclide in the whole area; δ is the mean square error of the window count rate of the calculated nuclide in the whole area; h is the flight altitude above the ground (m); v is the flight speed (km / h); and y is rounded down.

[0038] d. Perform weighted averaging on the measurement point data used for spectrum analysis to obtain the spectrum analysis data of the spectrum analysis measurement points; the weight calculation method is as follows:

[0039]

[0040] In the formula, ω i is the weight of the i-th point, n is the number of measurement points used for spectrum analysis; i is the serial number of the measurement points used for spectrum analysis, where the spectrum analysis point is the middle point and the others are arranged in the order of measurement points. For example, for 5-point spectrum analysis, the third point is the spectrum analysis point, and its front and back adjacent points are the second and fourth points respectively. The first point is pushed forward by one point from the front adjacent point, and the fifth point is pushed backward by one point from the back adjacent point, and so on.

[0041] e. Use the calibrated unit spectrum to deconvolve the result of step d and the deconvoluted spectrum data of the deconvoluted measurement point. The deconvoluted spectrum method is as follows:

[0042] X=A -1 M

[0043] Where: M is the spectrum data matrix of the spectrum measurement point; X is the content matrix of each nuclide; A is the unit spectrum matrix of each nuclide.

[0044] The method of the present invention can be called "adaptive multi-point weighted spectrum decomposition method". The "adaptive" in the method includes two aspects of "adaptive". One is to calculate the weighted average points according to the flight height and flight speed of the measurement data, and the other is to calculate the weighted average points according to the size of the measurement point count value. The formula provided by the present invention can not only calculate the weighted average points, but also calculate the weight of each measurement point.

[0045] In order to verify the correctness of this method, the method of the present invention was used to process the aerial gamma spectrum data of a certain survey area. Figure 4 is a cross-sectional plane diagram of a nuclide content obtained by the method of the present invention, Figure 4 Except for ore body No. 1, the other six ore bodies are all in the high value area of ​​certain nuclide content, and the content peak of ore body No. VI is very obvious. Figure 5 is the cross-sectional plane diagram of a nuclide content obtained using the current method. Figure 5 Among them, three ore bodies are in the non-high value area of ​​a certain nuclide content, and the peak value of the content of the Ⅵ ore body is far lower than Figure 4The peak value of a nuclide content in the sample. This shows that the method of the present invention can reduce noise, so that the content that is annihilated by noise can be displayed, such as the IV and V ore bodies; and the peak value is much higher than that of the current method, such as the VI ore body. The data processing results of this survey area prove the effectiveness of the method of the present invention.

[0046] The present invention can quickly and effectively remove noise while retaining abnormal information, thus improving the effect of airborne geophysical data processing. The present invention is mainly used in airborne geophysical exploration, mineral exploration for metal ores, oil and gas, and radioactive minerals, and can also be applied to tasks such as nuclear emergency aviation monitoring, nuclear counter-terrorism, airborne geophysical exploration, and environmental monitoring.

Claims

1. A spectrum analysis method for improving the accuracy of calculating nuclide content, characterized in that: The steps include: a. Calculate aviation gamma full spectrum correction parameters using calibration data; b. Use the aviation gamma spectrum correction parameters to perform aircraft background correction, cosmic ray correction, atmospheric radon correction, and altitude correction on the aviation gamma spectrum data after noise reduction in the survey area; c. Calculate the number of measurement points n used for spectrum analysis based on the flight altitude, flight speed and the nuclide window count rate. The calculation method is as follows: Where n is the number of measurement points used for spectrum analysis; m is the window count rate of the measurement point for the calculated nuclide; M is the mean window count rate of the calculated nuclide in the whole area; δ is the mean square error of the window count rate of the calculated nuclide in the whole area; h is the flight altitude in meters; v is the flight speed in kilometers per hour; y is rounded down; d. Perform weighted averaging on the measurement point data used for spectrum analysis to obtain the spectrum analysis data of the spectrum analysis measurement points; the weight calculation method is as follows: In the formula, ω i is the weight of the i-th point, i is the serial number of the measurement point used for spectrum analysis, where the spectrum analysis point is the middle point, and the others are arranged in the order of the measurement points; e. Use the calibrated unit spectrum to deconstruct the deconstructed spectrum data of the deconstructed measurement points.

2. The spectrum analysis method for improving the accuracy of calculating nuclide content according to claim 1 is characterized in that: In step a, the aviation gamma full spectrum correction parameters calculated using the calibration data are all full spectrum.

3. The spectrum decomposition method for improving the accuracy of calculating nuclide content according to claim 1 is characterized in that: In step b, background correction, cosmic ray correction, atmospheric radon correction, and altitude correction are all full-spectrum corrections.

4. The spectrum analysis method for improving the accuracy of calculating nuclide content according to claim 1 is characterized in that: In step d, when the spectrum analysis point is located at the end point of the measurement line, single-side measurement point weighting is adopted.

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