Correction method, device and equipment for factors affecting uranium fission prompt neutron logging

Abstract

The present invention relates to the field of geophysical exploration and mineral mining technology, and specifically to a correction method, device and equipment for uranium fission prompt neutron logging influencing factors, which can use a pre-built preset experimental device and a logging instrument to obtain measurement results under different logging influencing factors; accumulate time spectrum counts of thermal neutron time spectrum and epithermal neutron time spectrum in the measurement results to obtain the counting rate; correct the epithermal neutron counting rate; and then calculate the measurement sensitivity under different logging influencing factors; obtain each logging influencing factor and its sensitivity correction coefficient, and fit to obtain the change relationship; use the change relationship between each logging influencing factor and its correction coefficient to correct the measurement sensitivity during actual field logging. The technical solution provided by the present invention determines the correction method of different logging influencing factors, which can be used in the logging influencing factor correction technology of field logging, and improve the accuracy and reliability of logging results.

Description

Technical Field

[0001] The invention relates to the technical field of geophysical exploration and mineral mining, and in particular to a correction method, device and equipment for influencing factors of uranium fission prompt neutron logging. Background Art

[0002] Gamma logging mainly uses the gamma rays produced by uranium daughter nuclides for detection, and then estimates the uranium content of the ore body based on the uranium-radium balance. It is an important basis for the evaluation of uranium resources and reserves. It is an indirect uranium logging technology, which has inherent technical limitations for in-situ leachable sandstone uranium deposits with severe uranium-radium damage. Moreover, gamma logging cannot be used for monitoring the remaining uranium in uranium mining and smelting, a logging environment where the uranium-radium balance changes with the amount of mining, resulting in a lack of effective technical means for monitoring the remaining uranium in uranium mining and smelting.

[0003] Uranium fission prompt neutron logging is a measurement method that uses neutrons emitted by a neutron source or neutron generator to bombard uranium in the formation to cause fission, and then analyzes the uranium content in the formation by measuring the uranium fission neutron signal. It is currently an ideal direct uranium logging technology in the world.

[0004] However, due to the different factors affecting the logging of uranium fission prompt neutron logging instruments in uranium exploration and mining and metallurgy drilling, there are problems with the accuracy and reliability of the logging results. Summary of the invention

[0005] In view of this, the purpose of the present invention is to provide a method, device and equipment for correcting the influencing factors of uranium fission prompt neutron logging, so as to solve the problem that the logging influencing factors of uranium fission prompt neutron logging instruments in the prior art are different in uranium mine exploration and mining and metallurgy drilling, resulting in insufficient accuracy and reliability of logging results.

[0006] According to a first aspect of an embodiment of the present invention, a method for correcting influencing factors of uranium fission prompt neutron logging is provided, comprising:

[0007] Use pre-built preset experimental devices and logging instruments to obtain measurement results under different logging influencing factors;

[0008] Using the preset time window width, the thermal neutron time spectrum and the epithermal neutron time spectrum in the measurement results are counted and accumulated, and the counting rate is calculated according to the live time of the time spectrum measurement;

[0009] Calculating the thermal neutron lifetime according to the thermal neutron time spectrum;

[0010] The epithermal neutron count rate is corrected by neutron flux and neutron lifetime in sequence;

[0011] The measurement sensitivity under different logging influencing factors is calculated based on the corrected epithermal neutron counting rate;

[0012] According to the measurement sensitivity under different logging influencing factors, the correction coefficient under different logging influencing factors is obtained;

[0013] According to the variation law of each well logging influencing factor and its correction coefficient, the variation relationship between each well logging influencing factor and its correction coefficient is obtained by fitting;

[0014] The measurement sensitivity during actual on-site well logging is obtained, and the measurement sensitivity is corrected using the changing relationship between each well logging influencing factor and its correction coefficient.

[0015] Preferably, the counting rate is calculated based on the live time measured by the time spectrum, and the formula is as follows:

[0016]

[0017] in, N i For the i The count rate in a time window; n i.j The thermal or epithermal neutron time spectrum j Channel count.

[0018] Preferably, the epithermal neutron count rate is sequentially subjected to neutron flux correction and neutron lifetime correction, comprising:

[0019] The neutron flux correction is performed on the epithermal neutron count rate using the following formula:

[0020]

[0021] in, N ϕ is the epithermal neutron count rate corrected for the neutron flux; N e0 The epithermal neutron Ne1 window count rate obtained by the calibration of the logging tool; N e1 is the experimentally obtained epithermal neutron Ne1 window count rate; N e2 is the epithermal neutron Ne2 window count rate;

[0022] The neutron lifetime correction is performed on the epithermal neutron count rate after neutron flux correction, and the formula is as follows:

[0023]

[0024] in, N ec is the epithermal neutron count rate corrected for the neutron lifetime; tis the reference time of prompt neutrons in uranium fission; t 0 is the thermal neutron lifetime obtained by logging tool calibration; t 1 is the experimentally obtained thermal neutron lifetime.

[0025] Preferably, the measurement sensitivity under different logging influencing factors is calculated based on the corrected epithermal neutron count rate, and the formula is as follows:

[0026]

[0027] in, c u The uranium content of the preset experimental device; n i is the epithermal neutron counting rate obtained under different logging influencing factors; s i It is the measurement sensitivity under different logging influencing factors.

[0028] Preferably, the logging influencing factors include the logging aperture, iron casing thickness, PVC casing thickness, water layer thickness and well fluid density.

[0029] Preferably, the relationship between each logging influencing factor and its correction coefficient obtained by fitting includes:

[0030] The function is used to fit the changing law of each logging influencing factor and its correction coefficient, and the changing relationship between each logging influencing factor and its correction coefficient is obtained.

[0031] Preferably, the measurement sensitivity is corrected using the changing relationship between each well logging influencing factor and its correction coefficient, including:

[0032] According to the changing relationship between each logging influencing factor and its correction coefficient, the correction formula of logging influencing factor is as follows:

[0033]

[0034] in, s c It is the sensitivity of the probe at a certain measuring point in the wellbore during actual on-site logging; s 0 is the measurement sensitivity of the probe obtained by calibration on the well logging standard device; d is the borehole diameter at the measuring point; d 0 is the diameter of the probe tube; d s is the thickness of the iron casing; d p is the thickness of the PVC casing; r m is the well fluid density; function g 1( x), g 2( x ), g 3( x ), g 4( x )and g 5( x ) are the correction coefficients of measurement sensitivity for wellbore diameter, iron casing thickness, PVC casing thickness, water layer thickness and well fluid density, respectively.

[0035] According to a second aspect of an embodiment of the present invention, there is provided a device for correcting factors affecting uranium fission prompt neutron logging, comprising:

[0036] The experimental measurement module is used to obtain the measurement results under different logging influencing factors using the pre-built preset experimental device and logging instrument;

[0037] A counting rate calculation module is used to accumulate the time spectrum counts of the thermal neutron time spectrum and the epithermal neutron time spectrum in the measurement results using a preset time window width, and calculate the counting rate according to the live time measured by the time spectrum;

[0038] A counting rate correction module is used to calculate the thermal neutron lifetime according to the thermal neutron time spectrum; and perform neutron flux correction and neutron lifetime correction on the epithermal neutron counting rate in sequence;

[0039] The correction coefficient calculation module is used to calculate the measurement sensitivity under different logging influencing factors according to the corrected epithermal neutron count rate; obtain the correction coefficient under different logging influencing factors according to the measurement sensitivity under different logging influencing factors; and obtain the change relationship between each logging influencing factor and its correction coefficient according to the change law between each logging influencing factor and its correction coefficient;

[0040] The actual correction module is used to obtain the measurement sensitivity during actual on-site well logging, and to correct the measurement sensitivity using the changing relationship between each well logging influencing factor and its correction coefficient.

[0041] According to a third aspect of an embodiment of the present invention, there is provided a correction device for influencing factors of uranium fission prompt neutron logging, comprising:

[0042] A main controller, and a memory connected to the main controller;

[0043] The memory stores program instructions;

[0044] The main controller is used to execute program instructions stored in the memory to perform any of the above methods.

[0045] The technical solution provided by the embodiments of the present invention may have the following beneficial effects:

[0046] It can be understood that the technical solution shown in the present invention can use the pre-built preset experimental device and logging instrument to obtain measurement results under different logging influencing factors; accumulate the time spectrum counts of the thermal neutron time spectrum and the epithermal neutron time spectrum in the measurement results to obtain the counting rate; correct the epithermal neutron counting rate; and then calculate the measurement sensitivity under different logging influencing factors; obtain each logging influencing factor and its sensitivity correction coefficient, and fit the change relationship; use the change relationship between each logging influencing factor and its correction coefficient to correct the measurement sensitivity during actual field logging. The technical solution provided by the present invention determines the correction method of different logging influencing factors, which can be used in the logging influencing factor correction technology of field logging, and improve the accuracy and reliability of logging results.

[0047] It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0049] Figure 1 It is a schematic diagram of steps of a method for correcting influencing factors of uranium fission prompt neutron logging according to an exemplary embodiment;

[0050] Figure 2 is a schematic diagram of a preset experimental device according to an exemplary embodiment;

[0051] Figure 3 is a diagram showing a corresponding relationship between a thermal neutron and an epithermal neutron time spectrum and a window width according to an exemplary embodiment;

[0052] Figure 4 is a schematic diagram showing a change rule of sensitivity correction coefficient with wellbore diameter according to an exemplary embodiment;

[0053] Figure 5 is a schematic diagram showing a change rule of the sensitivity correction coefficient with the thickness of the iron casing according to an exemplary embodiment;

[0054] Figure 6 is a schematic diagram showing a change rule of the sensitivity correction coefficient with the thickness of the PVC casing according to an exemplary embodiment;

[0055] Figure 7 is a schematic diagram showing a change rule of the sensitivity correction coefficient with the thickness of the water layer according to an exemplary embodiment;

[0056] Figure 8It is a schematic diagram showing the variation of the sensitivity correction coefficient with the well fluid density according to an exemplary embodiment. DETAILED DESCRIPTION

[0057] Exemplary embodiments will be described in detail herein, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, the same numbers in different drawings represent the same or similar elements unless otherwise indicated. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Instead, they are merely examples of devices and methods consistent with some aspects of the present invention as detailed in the appended claims.

[0058] In one embodiment, Figure 1 FIG. 1 is a schematic diagram of steps of a method for correcting influencing factors of uranium fission prompt neutron logging according to an exemplary embodiment, see Figure 1 , a method for correcting the influencing factors of uranium fission prompt neutron logging is provided, including:

[0059] Step S11, using a pre-built preset experimental device and a logging instrument to obtain measurement results under different logging influencing factors;

[0060] Step S12, using a preset time window width, accumulating time spectrum counts for the thermal neutron time spectrum and the epithermal neutron time spectrum in the measurement results, and calculating the count rate according to the live time of the time spectrum measurement;

[0061] Step S13, calculating the thermal neutron lifetime according to the thermal neutron time spectrum;

[0062] Step S14, performing neutron flux correction and neutron lifetime correction on the epithermal neutron count rate in sequence;

[0063] Step S15, calculating the measurement sensitivity under different logging influencing factors according to the corrected epithermal neutron count rate;

[0064] Step S16, obtaining correction coefficients under different well logging influencing factors according to the measurement sensitivity under different well logging influencing factors;

[0065] Step S17, according to the variation law of each well logging influencing factor and its correction coefficient, fitting is performed to obtain the variation relationship between each well logging influencing factor and its correction coefficient;

[0066] Step S18, obtaining the measurement sensitivity during actual on-site well logging, and correcting the measurement sensitivity using the changing relationship between each well logging influencing factor and its correction coefficient.

[0067] It can be understood that the technical solution shown in this embodiment can use the pre-built preset experimental device and logging instrument to obtain measurement results under different logging influencing factors; accumulate the time spectrum counts of the thermal neutron time spectrum and the epithermal neutron time spectrum in the measurement results to obtain the counting rate; correct the epithermal neutron counting rate; and then calculate the measurement sensitivity under different logging influencing factors; obtain each logging influencing factor and its sensitivity correction coefficient, and fit the change relationship; use the change relationship between each logging influencing factor and its correction coefficient to correct the measurement sensitivity during actual field logging. The technical solution provided by this embodiment determines the correction method of different logging influencing factors, which can be used in the logging influencing factor correction technology of field logging to improve the accuracy and reliability of logging results.

[0068] In specific practice, the preset experimental device is built, see Figure 2 The device consists of a uranium fission prompt neutron logging parameter model, a uranium fission prompt neutron logging instrument, and materials such as iron casing, PVC casing, clean water, and bentonite.

[0069] by Figure 2 For example, the well logging parameter model constructed in this embodiment has an overall high h =5300mm, diameter φDk =1500mm, aperture φdk There are five types: 70, 100, 150, 220 and 300 mm. hk =1800mm, upper surrounding rock thickness hb1 =2000mm, the lower surrounding rock thickness hb2 =1500mm. The density of the ore layer and surrounding rock is about 2.0, and the overall weight of the model is 72t.

[0070] The uranium fission prompt neutron logging instrument consists of a neutron logging probe, a logging controller and other parts. The logging probe is divided into a neutron generator, a thermal neutron detector, an epithermal neutron detector, a measurement controller, a power supply, a communication module and other parts. All components are sealed in the pressure-bearing shell of the logging probe. The outer diameter of the probe is 600mm, and the logging depth can reach 1500m. According to the needs of uranium exploration and mining logging, auxiliary equipment such as logging winches, cables and car carrier platforms are configured.

[0071] In step S11, when the measurement results under different logging influencing factors are obtained by using the pre-built preset experimental device and the logging instrument, the logging influencing factors mainly include the logging aperture, iron casing thickness, PVC casing thickness, water layer thickness and well fluid density.

[0072] Therefore, the iron casing selected needs to meet different wall thicknesses and different pore sizes. This embodiment selects 14 "304" stainless steel casings with different wall thicknesses and different pore sizes. See Table 1. By combining SS4.5, SS5.5 and SS3.1~SS3.5, a thickness condition of 1mm~15mm wall thickness is formed for the iron casing thickness well logging influencing factor experiment. SS1.5, SS2.5, SS3.5, ..., SS10.5 with bottom are selected to carry out water layer thickness experiments, and iron casings with commonly used diameters for field logging are selected to carry out mud density influence experiments.

[0073] Table 1 Stainless steel casing parameters

[0074]

[0075] Regarding PVC casing, in order to meet the needs of the PVC casing thickness experiment, this embodiment selects 12 U-PVC casings for water supply with different wall thicknesses and different pore sizes, see Table 2, and through the combination of PVC casings of different diameters, a thickness condition of 3mm~30mm is formed for use in the PVC casing thickness well logging influencing factor experiment.

[0076] Table 2 U-PVC casing parameters

[0077]

[0078] Regarding the well fluid, this embodiment uses clean water or clean water with different proportions of bentonite to form a density of 1.00 to 1.35 g / cm according to the volume of the iron casing used in the well fluid thickness test and the well fluid density test. 3 Experiments were carried out using mud well fluid.

[0079] Experiments were carried out to obtain the measurement results under different logging influencing factors.

[0080] Well diameter experiment:

[0081] The uranium fission prompt neutron logging instrument was used to carry out borehole diameter experiments in logging parameter models with borehole diameters of 70, 100, 150, 220, and 300 mm. According to the depth calculated in the budget, the probe was placed into the fixed depth of the model wellbore, so that the probe notch was horizontally aligned with the center of the model's ore layer, and the probe was centered in the wellbore.

[0082] After evacuating the staff around the logging parameter model, start the logging software to start the measurement. The measurement time is controlled at about 10 minutes to ensure that the epithermal neutron count meets the measurement accuracy requirements. After the measurement is completed, wait for the probe to cool for more than 30 minutes before the staff can enter the area around the logging parameter model to remove the probe and prepare for the next aperture logging parameter model measurement experiment.

[0083] Iron casing thickness test:

[0084] The iron casings numbered SS2.1, SS2.2, SS2.3, SS2.4, and SS2.5 were selected and nested with the iron casings numbered SS3.5 and SS4.5 to obtain the combined casings with a wall thickness of 1 to 15 mm for the iron casing thickness experiment. First, the assembled iron casings were placed into the wellbore of the logging parameter model in sequence using an electric hoist so that the upper end of the assembled iron casing was basically aligned with the model wellhead. The logging cable was fixed with a fixed pulley, and the probe was placed into the assembled iron casing by an electric winch.

[0085] According to the pre-calculated depth, the combination of iron casing and probe tube is placed in a fixed position in the model wellbore, so that the probe tube notch is horizontally aligned with the center of the model ore layer, the iron casing is centered in the wellbore, and the probe tube is centered in the iron casing.

[0086] After evacuating the staff around the logging parameter model, start the logging software to start the measurement. The measurement time is controlled at about 10 minutes to ensure that the epithermal neutron count meets the measurement accuracy requirements. After the measurement is completed, the staff can take out the combination of the iron casing and the probe tube after the probe tube cools for more than 30 minutes to prepare for the next logging experiment of the iron casing thickness.

[0087] PVC casing thickness experiment:

[0088] In combination, PVC casings with numbers of p7.04, p6.04, p7.06, p5.08, p4.10, p5.05, p3.08, p2.11, and p1.13 were selected for nesting and combination, and a combination casing with a wall thickness of 3.8-30.8 mm was obtained to carry out the PVC casing thickness experiment. First, an electric hoist was used to place the assembled PVC casing into the wellbore of the logging parameter model in sequence, so that the upper end of the combined PVC casing was basically aligned with the model wellhead. The logging cable was fixed with a fixed pulley, and the probe was placed into the PVC casing by an electric winch.

[0089] According to the pre-calculated depth, the combination of PVC casing and probe tube is placed in a fixed position in the model wellbore, so that the probe tube notch is horizontally aligned with the center of the model ore layer, the PVC casing is centered in the wellbore, and the probe tube is centered in the PVC casing.

[0090] After evacuating the staff around the logging parameter model, the logging software is started for logging, and the measurement time is controlled within about 10 minutes to ensure that the epithermal neutron count meets the measurement accuracy requirements. After the measurement is completed, the probe tube is cooled for more than 30 minutes before the staff can remove the combination of the PVC pipe and the probe tube to prepare for the next PVC casing thickness logging experiment.

[0091] Water layer thickness experiment:

[0092] The iron casing with SS1.5~SS10.5 was selected to carry out the logging influencing factor experiment of different water layer thickness. After checking the sealing of the water outlet at the bottom of the iron casing, the iron casing was placed into the wellbore of the model using an electric hoist so that the upper end of the iron casing was slightly higher than the model wellhead. The logging cable was fixed with a fixed pulley, and the probe was placed into the iron casing by an electric winch. Then clean water was added to the iron casing, and the upper surface of the clean water was required to be slightly lower than the upper end of the iron casing to ensure that the clean water would not fall into the model wellbore.

[0093] According to the pre-calculated depth, the combination of iron casing, probe tube and clean water is placed in a fixed position in the model wellbore, so that the probe tube notch is horizontally aligned with the center of the model, the iron casing is centered in the wellbore, and the probe tube is centered in the iron casing.

[0094] After evacuating the staff around the logging parameter model, start the logging software to start the measurement. The measurement time is controlled at about 10 minutes to ensure that the epithermal neutron count meets the measurement accuracy requirements. After the measurement is completed, the probe tube is cooled for more than 30 minutes before the staff can remove the iron casing, probe tube, and clean water combination to prepare for the next water layer thickness logging experiment.

[0095] Well fluid density experiment:

[0096] 1.07, 1.15, 1.21, 1.28, 1.35g / cm 3 Well logging experiments of 5 well fluid densities were conducted. Similar to the water layer thickness test method, a certain amount of bentonite was added to the water to reach a preset density to form a mud with uniform density. The experiment was carried out using an iron casing with a common diameter numbered ss5.5. After checking the sealing of the water outlet at the bottom of the iron casing, an electric hoist was used to place the iron casing into the wellbore of the model so that the upper end of the iron casing was slightly higher than the model wellhead. The logging cable was fixed with a fixed pulley, and the probe was placed into the iron casing by an electric winch. Then the pre-prepared mud was added to the iron casing, and the upper surface of the mud was required to be slightly lower than the upper end of the iron casing to ensure that the mud would not spill into the model wellbore.

[0097] According to the pre-calculated depth, the combination of iron casing, probe tube and mud is placed in a fixed position on the model, so that the probe tube notch is horizontally aligned with the center of the model, the iron casing is centered in the wellbore, and the probe tube is centered in the iron casing.

[0098] After evacuating the staff around the logging parameter model, start the logging software to start the measurement. The measurement time is controlled at about 10 minutes to ensure that the epithermal neutron count meets the measurement accuracy requirements. After the measurement is completed, the probe tube is cooled for more than 30 minutes before the staff can remove the iron casing, probe tube, and mud assembly to prepare for the next mud density logging experiment.

[0099] After the experiment is completed and the measurement results are obtained, data processing is performed. In step S12, the thermal neutron time spectrum and the epithermal neutron time spectrum in the measurement results are counted and accumulated using the preset time window width. The count rate is calculated based on the live time of the time spectrum measurement. The formula is as follows:

[0100]

[0101] in, N i For the i When calculating the window count rate of the thermal neutron time spectrum, i Indicates Nt1 or Nt2; when calculating the window count rate of the epithermal neutron time spectrum, i Indicates Ne1 or Ne2; n i.j The thermal or epithermal neutron time spectrum j Channel count.

[0102] For preset time window width, see Table 3.

[0103] Table 3 Time window parameter table

[0104]

[0105] The time spectrum of the uranium fission prompt neutron logging tool is set. The channel width of the thermal neutron and epithermal neutron time spectrum is 2μs. The corresponding relationship between the window width and the time spectrum can be found in Figure 3 .

[0106] In step S14, neutron flux correction and neutron lifetime correction are sequentially performed on the epithermal neutron count rate, including:

[0107] The neutron flux correction is performed on the epithermal neutron count rate using the following formula:

[0108]

[0109] in, N ϕ is the epithermal neutron count rate corrected for neutron flux, s -1 ; N e0 is the epithermal neutron Ne1 window count rate obtained by logging tool calibration, s -1 ; N e1 is the experimentally obtained epithermal neutron Ne1 window count rate, s -1 ; N e2 is the epithermal neutron Ne2 window count rate, s -1 .

[0110] The neutron lifetime correction is performed on the epithermal neutron count rate after neutron flux correction, and the formula is as follows:

[0111]

[0112] in, N ec is the epithermal neutron count rate corrected for the neutron lifetime, s -1 ; t is the reference time of prompt neutrons of uranium fission, s; t 0 is the thermal neutron lifetime obtained by logging tool calibration, μs; t 1 is the experimentally obtained thermal neutron lifetime, μs.

[0113] In step S15, the measurement sensitivity under different logging influencing factors is calculated according to the corrected epithermal neutron count rate, and the formula is as follows:

[0114]

[0115] in, c u is the uranium content of the preset experimental device, 10 -6 ; n i is the epithermal neutron counting rate obtained under different logging factors, s -1 ; s i is the measurement sensitivity under different logging influencing factors, s -1 / 10 -6 .

[0116] In step S16, correction coefficients under different well logging influencing factors are obtained according to the measurement sensitivity under different well logging influencing factors.

[0117] In specific practice, in order to use the sensitivity of the uranium fission prompt neutron logging instrument calibrated in the logging standard device (〔2018〕National Defense Measurement and Standardization Area Certificate No. G2850) for field logging, and make the measurement sensitivity obtained by metrological verification applicable to different wellbore conditions, it is necessary to correct the actual sensitivity of the logging instrument at each logging point.

[0118] For the aperture correction factor:

[0119] The aperture correction factor is determined based on the sensitivity obtained from the wellbore experiment and the calibration of the well logging standard device. The formula is as follows:

[0120]

[0121] in, d is the borehole diameter of the measurement experiment, mm; g 1(d ) is the aperture d Sensitivity correction factor, 1; s 1( d ) is the aperture d The measurement sensitivity, s -1 / 10 -6 ; s 0 is the measurement sensitivity calibrated in the well logging standard device, s -1 / 10 -6 .

[0122] Iron casing thickness correction factor:

[0123] The iron casing thickness correction factor is determined based on the sensitivity obtained from the iron casing thickness experiment and the calibration of the logging standard device. The formula is as follows:

[0124]

[0125] in, d s The thickness of the iron casing used in the measurement experiment, mm; g 2( d s ) is the thickness of the iron casing d s Sensitivity correction factor, 1; s 2( d s ) is the thickness of the iron casing d s The measurement sensitivity, s -1 / 10 -6 ; s 0 is the measurement sensitivity calibrated in the well logging standard device, s -1 / 10 -6 .

[0126] PVC casing thickness correction factor:

[0127] The PVC casing thickness correction factor is determined based on the sensitivity obtained from the PVC casing thickness experiment and the calibration of the well logging standard device. The formula is as follows:

[0128]

[0129] In the formula, d p The thickness of the PVC casing used in the measurement experiment, mm; g 3( d p ) is the thickness of the PVC casing d p Sensitivity correction factor, 1; s 3( d p) is the thickness of the PVC casing d s The measurement sensitivity, s -1 / 10 -6 ; s 0 is the measurement sensitivity calibrated in the well logging standard device, s -1 / 10 -6 .

[0130] Water layer thickness correction factor:

[0131] The water layer thickness correction coefficient is determined based on the sensitivity obtained from the water layer thickness experiment and the calibration of the well logging standard device. The formula is as follows:

[0132]

[0133] In the formula, d w is the thickness of the water layer in the measurement experiment, mm; g 4( d w ) is the thickness of the water layer d w Sensitivity correction factor, 1; s 4( d w ) is the thickness of the water layer d w The measurement sensitivity, s -1 / 10 -6 ; s 0 is the measurement sensitivity calibrated in the well logging standard device, s -1 / 10 -6 .

[0134] Well fluid density correction factor:

[0135] The correction factor of well fluid density is determined based on the sensitivity of well fluid density experiment and water layer thickness experiment of the same thickness. The formula is as follows:

[0136]

[0137] In the formula, r m To measure the experimental mud density, g / cm 3 ; g 5( r m ) is the well fluid density r m Sensitivity correction factor, 1; s 5( r m ) is the well fluid density r m The measurement sensitivity, s -1 / 10 -6 ; s 4 is the measurement sensitivity of water layer with the same thickness, s -1 / 10 -6 .

[0138] In step S17, the relationship between each logging influencing factor and its correction coefficient is obtained by fitting, including:

[0139] The function is used to fit the changing law of each logging influencing factor and its correction coefficient, and the changing relationship between each logging influencing factor and its correction coefficient is obtained.

[0140] For the analysis of aperture correction coefficient, according to the variation law of wellbore aperture and sensitivity correction coefficient, see Figure 4 , the quadratic exponential function is used to fit the relationship between the sensitivity correction coefficient and the borehole diameter. The relationship formula is as follows:

[0141]

[0142] In the formula, m a1 , m b1 is the fitting coefficient of the sensitivity correction coefficient changing with the well diameter, 1; d is the borehole diameter, mm.

[0143] For the analysis of iron casing thickness correction coefficient, according to the variation law of iron casing thickness and sensitivity correction coefficient, see Figure 5 The influence of the iron casing thickness on the measurement sensitivity is very small. The relationship between the sensitivity correction coefficient and the iron casing thickness can be obtained by using a first-order exponential function fitting. The relationship formula is as follows:

[0144]

[0145] In the formula, m a2 is the fitting coefficient of the sensitivity correction coefficient changing with the thickness of the iron casing, 1; d s is the thickness of the iron casing, mm.

[0146] For the analysis of PVC casing thickness correction coefficient, according to the variation law of PVC casing thickness and sensitivity correction coefficient, see Figure 6 , the quadratic exponential function is used to fit the relationship between the sensitivity correction coefficient and the thickness of the PVC casing. The relationship formula is as follows:

[0147]

[0148] In the formula, m a3 , m b3 is the fitting coefficient of the sensitivity correction coefficient changing with the thickness of the PVC casing, 1; d p is the thickness of the PVC casing, mm.

[0149] For the analysis of water layer thickness correction coefficient, according to the variation law of water layer thickness and sensitivity correction coefficient, see Figure 7 , the quadratic exponential function is used to fit the relationship between the sensitivity correction coefficient and the water layer thickness. The relationship formula is as follows:

[0150]

[0151] In the formula, m a4 , m b4 is the fitting coefficient of the sensitivity correction coefficient changing with the thickness of the water layer, 1; d p is the water layer thickness, mm.

[0152] For the analysis of well fluid density correction factor, according to the variation law of well fluid density and sensitivity correction factor, see Figure 8 , the change of well fluid density has little effect on the measurement sensitivity. The relationship between the sensitivity correction coefficient and the change of well fluid density can be obtained by fitting a first-order exponential function. The change relationship formula is as follows:

[0153]

[0154] In the formula, m a5 is the fitting coefficient of the sensitivity correction factor changing with the well fluid density, 1; r m is the well fluid density, g / cm 3 .

[0155] In step S18, the measurement sensitivity is corrected using the changing relationship between each logging influencing factor and its correction coefficient, including:

[0156] According to the changing relationship between each logging influencing factor and its correction coefficient, the correction formula of logging influencing factor is as follows:

[0157]

[0158] in, s c It is the sensitivity of the probe at a certain measuring point in the wellbore during actual on-site logging; s 0 is the measurement sensitivity of the probe obtained by calibration on the well logging standard device; d is the borehole diameter at the measuring point;d 0 is the diameter of the probe tube; d s is the thickness of the iron casing; d p is the thickness of the PVC casing; r m is the well fluid density; function g 1( x ), g 2( x ), g 3( x ), g 4( x )and g 5( x ) are the correction coefficients of measurement sensitivity for wellbore diameter, iron casing thickness, PVC casing thickness, water layer thickness and well fluid density, respectively.

[0159] According to the relationship between the sensitivity correction coefficient and the well diameter, iron casing thickness, PVC casing thickness, water layer thickness, and well fluid density, when the probe is located at a certain measuring point in the wellbore during field logging, the measurement sensitivity is affected by the above factors at the same time, and the measurement sensitivity can be corrected using the above formula.

[0160] For the above formula, the correction factor for each measuring point is determined by the following formula:

[0161]

[0162]

[0163]

[0164]

[0165]

[0166] This embodiment uses the uranium fission prompt neutron logging instrument independently developed in my country to carry out experiments with different apertures, iron casing thickness, PVC casing thickness, well fluid thickness, and well fluid density in a model built in advance with known ore layer and surrounding rock parameters, determine the influence correction method and correction coefficient, and successfully use it in the logging influencing factor correction technology for field well logging.

[0167] According to a second aspect of an embodiment of the present invention, there is provided a device for correcting factors affecting uranium fission prompt neutron logging, comprising:

[0168] The experimental measurement module is used to obtain the measurement results under different logging influencing factors using the pre-built preset experimental device and logging instrument;

[0169] A counting rate calculation module is used to accumulate the time spectrum counts of the thermal neutron time spectrum and the epithermal neutron time spectrum in the measurement results using a preset time window width, and calculate the counting rate according to the live time measured by the time spectrum;

[0170] A counting rate correction module is used to calculate the thermal neutron lifetime according to the thermal neutron time spectrum; and perform neutron flux correction and neutron lifetime correction on the epithermal neutron counting rate in sequence;

[0171] The correction coefficient calculation module is used to calculate the measurement sensitivity under different logging influencing factors according to the corrected epithermal neutron count rate; obtain the correction coefficient under different logging influencing factors according to the measurement sensitivity under different logging influencing factors; and obtain the change relationship between each logging influencing factor and its correction coefficient according to the change law between each logging influencing factor and its correction coefficient;

[0172] The actual correction module is used to obtain the measurement sensitivity during actual on-site well logging, and to correct the measurement sensitivity using the changing relationship between each well logging influencing factor and its correction coefficient.

[0173] According to a third aspect of an embodiment of the present invention, there is provided a correction device for influencing factors of uranium fission prompt neutron logging, comprising:

[0174] A main controller, and a memory connected to the main controller;

[0175] The memory stores program instructions;

[0176] The main controller is used to execute program instructions stored in the memory to perform any of the above methods.

[0177] It can be understood that the same or similar parts of the above embodiments can be referenced to each other, and the contents not described in detail in some embodiments can refer to the same or similar contents in other embodiments.

[0178] It should be noted that, in the description of the present invention, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. In addition, in the description of the present invention, unless otherwise specified, the meaning of "plurality" refers to at least two.

[0179] Any process or method description in a flowchart or otherwise described herein may be understood to represent a module, segment or portion of code that includes one or more executable instructions for implementing the steps of a specific logical function or process, and the scope of the preferred embodiments of the present invention includes alternative implementations in which functions may not be performed in the order shown or discussed, including performing functions in a substantially simultaneous manner or in the reverse order depending on the functions involved, which should be understood by those skilled in the art to which the embodiments of the present invention belong.

[0180] It should be understood that the various parts of the present invention can be implemented by hardware, software, firmware or a combination thereof. In the above-mentioned embodiments, multiple steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0181] A person skilled in the art may understand that all or part of the steps in the method for implementing the above-mentioned embodiment may be completed by instructing related hardware through a program, and the program may be stored in a computer-readable storage medium, which, when executed, includes one or a combination of the steps of the method embodiment.

[0182] In addition, each functional unit in each embodiment of the present invention may be integrated into a processing module, or each unit may exist physically separately, or two or more units may be integrated into one module. The above-mentioned integrated module may be implemented in the form of hardware or in the form of a software functional module. If the integrated module is implemented in the form of a software functional module and sold or used as an independent product, it may also be stored in a computer-readable storage medium.

[0183] The storage medium mentioned above can be a read-only memory, a magnetic disk or an optical disk, etc.

[0184] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0185] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A method for correcting influencing factors of uranium fission prompt neutron logging, characterized in that: include: Use pre-built preset experimental devices and logging instruments to obtain measurement results under different logging influencing factors; Using the preset time window width, the thermal neutron time spectrum and the epithermal neutron time spectrum in the measurement results are counted and accumulated, and the counting rate is calculated according to the live time of the time spectrum measurement; Calculating the thermal neutron lifetime according to the thermal neutron time spectrum; The epithermal neutron count rate is corrected by neutron flux and neutron lifetime in sequence; The measurement sensitivity under different logging influencing factors is calculated based on the corrected epithermal neutron counting rate; According to the measurement sensitivity under different logging influencing factors, the correction coefficient under different logging influencing factors is obtained; According to the variation law of each well logging influencing factor and its correction coefficient, the variation relationship between each well logging influencing factor and its correction coefficient is obtained by fitting; The measurement sensitivity during actual on-site well logging is obtained, and the measurement sensitivity is corrected using the changing relationship between each well logging influencing factor and its correction coefficient.

2. The method for correcting the influencing factors of uranium fission prompt neutron logging according to claim 1, characterized in that: The counting rate is calculated based on the live time measured by the time spectrum, and the formula is as follows: in, N i For the i The count rate in a time window; n i.j The thermal or epithermal neutron time spectrum j Channel count.

3. The method for correcting the influencing factors of uranium fission prompt neutron logging according to claim 2, characterized in that: The epithermal neutron count rate is corrected by neutron flux and neutron lifetime in sequence, including: The neutron flux correction is performed on the epithermal neutron count rate using the following formula: in, N ϕ is the epithermal neutron count rate corrected for the neutron flux; N e0 The epithermal neutron Ne1 window count rate obtained by the calibration of the logging tool; N e1 is the experimentally obtained epithermal neutron Ne1 window count rate; N e2 is the epithermal neutron Ne2 window count rate; The neutron lifetime correction is performed on the epithermal neutron count rate after neutron flux correction, and the formula is as follows: in, N ec is the epithermal neutron count rate corrected for the neutron lifetime; t is the reference time of prompt neutrons in uranium fission; t 0 is the thermal neutron lifetime obtained by logging tool calibration; t 1 is the experimentally obtained thermal neutron lifetime.

4. The method for correcting the influencing factors of uranium fission prompt neutron logging according to claim 3, characterized in that: The measurement sensitivity under different logging influencing factors is calculated based on the corrected epithermal neutron count rate. The formula is as follows: in, c u The uranium content of the preset experimental device; n i is the epithermal neutron counting rate obtained under different logging influencing factors; s i It is the measurement sensitivity under different logging influencing factors.

5. The method for correcting the influencing factors of uranium fission prompt neutron logging according to claim 4, characterized in that: The logging influencing factors include the logging aperture, iron casing thickness, PVC casing thickness, water layer thickness and well fluid density.

6. The method for correcting the influencing factors of uranium fission prompt neutron logging according to claim 1, characterized in that: The fitting results show the changing relationship between each logging influencing factor and its correction coefficient, including: The function is used to fit the changing law of each logging influencing factor and its correction coefficient, and the changing relationship between each logging influencing factor and its correction coefficient is obtained.

7. The method for correcting the influencing factors of uranium fission prompt neutron logging according to claim 5, characterized in that: The measurement sensitivity is corrected using the changing relationship between each logging influencing factor and its correction coefficient, including: According to the changing relationship between each logging influencing factor and its correction coefficient, the correction formula of logging influencing factor is as follows: in, s c It is the sensitivity of the probe at a certain measuring point in the wellbore during actual on-site logging; s 0 is the measurement sensitivity of the probe obtained by calibration on the well logging standard device; d is the borehole diameter at the measuring point; d 0 is the diameter of the probe tube; δ s is the thickness of the iron casing; δ p is the thickness of the PVC casing; ρ m is the well fluid density; function g 1( x ), g 2( x ), g 3( x ), g 4( x )and g 5( x ) are the correction coefficients of measurement sensitivity for wellbore diameter, iron casing thickness, PVC casing thickness, water layer thickness and well fluid density, respectively.

8. A correction device for influencing factors of uranium fission prompt neutron logging, characterized in that: include: The experimental measurement module is used to obtain the measurement results under different logging influencing factors using the pre-built preset experimental device and logging instrument; A counting rate calculation module is used to accumulate the time spectrum counts of the thermal neutron time spectrum and the epithermal neutron time spectrum in the measurement results using a preset time window width, and calculate the counting rate according to the live time measured by the time spectrum; A counting rate correction module is used to calculate the thermal neutron lifetime according to the thermal neutron time spectrum; and perform neutron flux correction and neutron lifetime correction on the epithermal neutron counting rate in sequence; The correction coefficient calculation module is used to calculate the measurement sensitivity under different logging influencing factors according to the corrected epithermal neutron count rate; obtain the correction coefficient under different logging influencing factors according to the measurement sensitivity under different logging influencing factors; and obtain the change relationship between each logging influencing factor and its correction coefficient according to the change law between each logging influencing factor and its correction coefficient; The actual correction module is used to obtain the measurement sensitivity during actual on-site well logging, and to correct the measurement sensitivity using the changing relationship between each well logging influencing factor and its correction coefficient.

9. A correction device for influencing factors of uranium fission prompt neutron logging, characterized in that: include: A main controller, and a memory connected to the main controller; The memory stores program instructions; The main controller is used to execute program instructions stored in the memory and execute the method according to any one of claims 1 to 7.

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