CN104074501A - Fission neutron well logging correction method - Google Patents

Abstract

The invention relates to a fission neutron well logging correction method, which comprises the following steps that: 1, a correction counting rate of a neutron monitor of a tested wellhole is obtained; 2, a water correction factor is obtained; 3, the neutron counting rates near a well wall and along a well axis after the water correction in a tested well are obtained; and 4, the neutron counting rates near the well wall and along the well axis after the epithermal neutron service life correction in the tested well are obtained. The method provided by the invention can be used for directly measuring the uranium content. Compared with drill hole rock core sampling chemical analysis results, the method has the advantages that the deviation does not exceed 10 percent. The uranium ore grade is more objectively reflected; particularly in sections with damaged uranium-radium balance, conventional gamma well logging is combined, and a uranium-radium balance factor of a drill hole ore block can be determined in site; and the rock core sampling quantity is reduced, and the uranium resource investigation cost is reduced. The method can be used for accurately measuring the uranium leaching rate in mining using the leaching technology, avoids the environment pollution and the cost waste due to unquestioning excessive liquid injection in the process of the mining using the leaching technology, and has important practical significance on improving the efficiency of the mining using the leaching technology, reducing the cost and protecting the environment.

Description

A kind of fission neutron well logging modification method

Technical field

The invention belongs to core and radiation environmental monitoring metering field technical field, be specifically related to a kind of fission neutron logging instrument and soak for uranium exploration reserves and ground the modification method of adopting the calculating of smelting residue uranium resource amount.

Background technology

Fission neutron logging technique belongs to the logging technique of directly surveying uranium, and this technology starts from the seventies in last century, comprises prompt neutron logging technique and DFN technology.Prompt neutron logging instrument and deferred neutron logging instrument are widely used in to uranium exploration in the world to middle nineteen seventies, its sensitivity of surveying uranium reaches 10 ^-4g/g, has reached the minimum production-grade of adopting of can ground soaking exploration of sandstone type uranium deposits.

Often use at present γ-ray logging to carry out uranium resource exploration and reserves calculating, γ-ray logging is indirectly to calculate uranium content by measuring radium content.The fission neutron logging technique of directly surveying uranium still belongs to the starting stage, and fission neutron logging instrument in use, along with the loss of neutron tube and the natural decay of tritium, the neutron population that neutron tube produces progressively reduces, different time in same ore deposit section is measured, and the epithermal neutron number recording also can reduce.And when anhydrous in wellhole, well diameter has no significant effect fission neutron well logging; But in the time having water in wellhole, the protium in water is significant on the impact of fission neutron well logging response, and this impact is relevant to hole diameter size; The counting rate of thermal neutron or epithermal neutron is decided by the slowing down power(SDP) of water, and water has the impact of can not ignore to the accuracy of fission neutron well logging, and this impact needs water correction factor to eliminate.Not yet there is at present the modification method of fission neutron well logging, cannot realize the effective correction to fission neutron well logging, the accurate calculating of uranium resource amount is brought to impact.

Summary of the invention

The object of the invention is to soak the application of adopting in smelting a kind of modification method is provided can ground soak exploration of sandstone type uranium deposits and ground for directly surveying uranium logging technique, the scene of realizing field boring uranium content fast, Measurement accuracy.

The present invention is achieved in that a kind of fission neutron logging instrument modification method, comprises the following steps:

Step 1, obtain the correction counting rate of neutron monitor in tested wellhole

Neutron count rate S1 and S2 while gathering respectively in tested wellhole along borehole axis with by the borehole wall by fission neutron instrument, and the difference △ M of two neutron monitor MON1 of fission neutron instrument and the neutron count rate of MON2 record while gathering respectively in tested wellhole along borehole axis with by the borehole wall ₁with △ M ₂; In fission neutron logging module standard set-up, gather respectively along borehole axis and when the borehole wall difference △ M of two neutron monitor MON1 of fission neutron instrument and the neutron count rate of MON2 record ₀with △ M ₀ ^';

Neutron monitor correction neutron count rate DS1 and DS2 while obtaining respectively in tested wellhole according to formula (1) and (2) that neutron monitor is along borehole axis with by the borehole wall;

$\mathrm{DS}1=S1\·\frac{{\mathrm{\ΔM}}_0}{{\mathrm{\ΔM}}_1}---\left(1\right)$

$\mathrm{DS}2=S2\·\frac{{\mathrm{\ΔM}}_{0^{\′}}}{\mathrm{\Δ}{M}_2}---\left(2\right)$

Step 2, obtain water correction factor

1, gather the diameter D of tested wellhole _k, fission neutron logging instrument test tube diameter D _t, obtain according to formula (3) tested wellhole inwall and described fission neutron logging instrument test tube outer wall between clear water situation under water layer thickness d;

$d=\frac{1}{2}(D_k-D_T)---\left(3\right)$

2, obtain containing the equivalent water layer thickness d ' in mud situation according to formula (4),

In formula, d ' is the equivalent water layer thickness of well liquid, mm;

ρ _sandby gritty density in mud, g/cm ³;

ρ _mudfor mud balance, g/cm ³;

ρ _waterfor density, g/cm ³;

3, according to formula (5) obtain after fission neutron well logging alignment along borehole axis water correction factor μ _x1; According to formula (6) obtain after fission neutron well logging alignment by borehole wall water correction factor μ _x2;

μ _X1=0.7643e ^0.0200d' （5）

μ _X2=0.8761e ^0.0124d′ （6）

Step 3, obtain after tested WIH correction along borehole axis neutron count rate SS1 according to formula (9); After obtaining tested WIH correction according to formula (10), depend on borehole wall neutron count rate SS2;

SS1=DS1·μ _X1 （9）

SS2=DS2·μ _X2 （10）

Step 4, according to formula (11) obtain by well logging in the epithermal neutron life-span revise after along borehole axis neutron count rate CS1; Obtain by the epithermal neutron life-span in well logging and revise the rear borehole wall neutron count rate CS2 of leaning on according to formula (12);

$\mathrm{CS}1=\mathrm{SS}1\·\frac{{\mathrm{\τ}}_0}{{\mathrm{\τ}}_1}\·\frac{e^{(-192/{\mathrm{\τ}}_0)}}{e^{(-192/{\mathrm{\τ}}_1)}}---\left(11\right)$

$\mathrm{CS}2=\mathrm{SS}2\·\frac{{\mathrm{\τ}}_0}{{\mathrm{\τ}}_1}\·\frac{e^{(-192/{\mathrm{\τ}}_0)}}{e^{(-192/{\mathrm{\τ}}_1)}}---\left(12\right)$

In formula:

CS1 and CS2 unit are s ^-1;

τ ₀---the epithermal neutron life-span recording in fission neutron logging module standard set-up, μ s;

τ ₁---the epithermal neutron life-span recording in tested wellhole, μ s.

Described formula (5) and formula (6) obtain by the following method:

In order to measure the water correction factor of different pore size, build the uranium content building blocks logging module of test use, its physical dimension is 3.5m × 1.5m × 1.7m, aperture is 0.3m, the high 0.6m of base, top cover 0.4m, uranium ore section thickness is 0.7m;

In building blocks model wellhole, put into the ferule of different-diameter and sealed bottom, ferule diameter is within the scope of 79mm～259mm, select the ferule of 6 diameter values, measure injected water front and back in ferule and, along neutron count rate S3 and the S3' of borehole axis, calculate actual measurement along borehole axis water correction factor μ by formula (7) _x1 ^'; Same, measure the neutron count rate S4 and the S4' that in ferule, before and after injected water, lean on the borehole wall, calculate actual measurement by borehole wall water correction factor μ by formula (8) _x2 ^'; Concrete data are in table 1;

${\mathrm{\μ}}_{{X1}^{\′}}=\frac{S3}{S{3}^{\′}}---\left(7\right)$

${\mathrm{\μ}}_{{X2}^{\′}}=\frac{S4}{S{4}^{\′}}---\left(8\right)$

Table 1 fission neutron logging instrument actual measurement water correction factor

According to the data in table 1, draw matched curve, and then obtain formula (5) and (6).

Beneficial effect of the present invention is as follows:

(1) changed uranium ore gamma well logging in the past and can only indirectly calculate by surveying radium the well logging pattern of uranium, by applying modification method of the present invention, uranium content can be directly measured in fission neutron well logging, and with the comparison of drill core sampling chemical analysis results, deviation is no more than 10%.Modification method of the present invention provides technical support for the application of directly surveying uranium fission neutron well logging technology;

(2) apply fission neutron well logging result of the present invention and more objectively reacted uranium ore grade, especially in the destroyed location of uranium radium balance, in conjunction with conventional γ-ray logging, can in-situ determination the uranium radium coefficient of balance of boring ore deposit section, reduced boring sample quantity, reduced uranium resource and reconnoitre cost;

(3) apply fission neutron of the present invention well logging modification method can Measurement accuracy mining using leaching technology in uranium leaching rate; avoid in mining using leaching technology process because of environment pollution and cost waste that blindly excessive fluid injection causes, to improve soak adopt smelting efficiency, reduce costs, protection of the environment has important practical significance.

Brief description of the drawings

Fig. 1 is Drilling Water layer thickness schematic diagram in the present invention;

Fig. 2 is fission neutron well logging water correction matched curve in the present invention;

In figure, 1 is the test tube diameter of fission neutron logging instrument, 2 be tested wellhole inwall and described fission neutron logging instrument test tube outer wall between clear water situation under water layer thickness, 3 diameters that are tested wellhole.

Detailed description of the invention

Below in conjunction with drawings and Examples, a kind of fission neutron logging instrument modification method of the present invention is introduced:

As shown in Figure 1, a kind of fission neutron logging instrument calibration correction method, concrete steps are as follows:

Step 1, obtain the correction counting rate of neutron monitor in tested wellhole

Neutron count rate S1 and S2 while gathering respectively in tested wellhole along borehole axis with by the borehole wall by fission neutron instrument, and the difference △ M of two neutron monitor MON1 of fission neutron instrument and the neutron count rate of MON2 record while gathering respectively in tested wellhole along borehole axis with by the borehole wall ₁with △ M ₂; In fission neutron logging module standard set-up, gather respectively along borehole axis and when the borehole wall difference △ M of two neutron monitor MON1 of fission neutron instrument and the neutron count rate of MON2 record ₀with △ M ₀ ^';

Fission neutron logging instrument is to calibrate on fission neutron logging module standard set-up, and fission neutron logging module standard set-up is the technical method recommended with reference to 1989 No. 309 technical reports of International Atomic Energy Agency and the construction of domestic and international similar standard facility.

Neutron monitor correction neutron count rate DS1 and DS2 while obtaining respectively in tested wellhole according to formula (1) and (2) that neutron monitor is along borehole axis with by the borehole wall;

$\mathrm{DS}1=S1\·\frac{{\mathrm{\ΔM}}_0}{{\mathrm{\ΔM}}_1}---\left(1\right)$

$\mathrm{DS}2=S2\·\frac{{\mathrm{\ΔM}}_{0^{\′}}}{\mathrm{\Δ}{M}_2}---\left(2\right)$

In formula:

S1, △ M ₁, △ M ₀, DS1, S2, △ M ₂, △ M ₀ ^', DS2 unit be s ^-1;

Step 2, obtain water correction factor

1, gather the diameter D of tested wellhole _k, fission neutron logging instrument test tube diameter D _t, obtain according to formula (3) tested wellhole inwall and described fission neutron logging instrument test tube outer wall between clear water situation under water layer thickness d; As shown in Figure 1;

$d=\frac{1}{2}(D_k-D_T)---\left(3\right)$

In formula, D _k, D _t, d unit be mm;

2, the well liquid in the boring of field is not clear water conventionally, but there is the mud of certain weight proportion, in mud, contained gravel can be ignored the impact of neutron well logging, impact on fission neutron well logging is mainly derived from the water in mud, obtain containing the equivalent water layer thickness d ' in mud situation according to formula (4)

In formula, d ' is the equivalent water layer thickness of well liquid, mm;

ρ _sandby gritty density in mud, g/cm ³, its value is 2.65g/cm ³(quartz sand density value);

ρ _mudfor mud balance, g/cm ³;

ρ _waterfor density, g/cm ³;

3, according to formula (5) obtain after fission neutron well logging alignment along borehole axis water correction factor μ _x1; According to formula (6) obtain after fission neutron well logging alignment by borehole wall water correction factor μ _x2;

μ _X1=0.7643e ^0.0200d′ （5）

μ _X2=0.8761e ^0.0124d′ （6）

Calculate fission neutron well logging along borehole axis with by the water correction factor table of the borehole wall, in table 2 by formula (5) and (6).

Table 2 fission neutron well logging water correction factor table

Described formula (5) and formula (6) obtain by the following method:

In order to measure the water correction factor of different pore size, build the uranium content building blocks logging module of test use, its physical dimension is 3.5m × 1.5m × 1.7m, aperture is φ 0.3m, the high 0.6m of base, top cover 0.4m, uranium ore section thickness is 0.7m.

In building blocks model wellhole, put into the ferule of different-diameter and sealed bottom, ferule diameter is within the scope of 79mm～259mm, select the ferule of 6 diameter values, measure injected water front and back in ferule and, along neutron count rate S3 and the S3' of borehole axis, calculate actual measurement along borehole axis water correction factor μ by formula (7) _x1 ^'; Same, measure the neutron count rate S4 and the S4' that in ferule, before and after injected water, lean on the borehole wall, calculate actual measurement by borehole wall water correction factor μ by formula (8) _x2 ^'; Concrete data are in table 1;

${\mathrm{\μ}}_{{X1}^{\′}}=\frac{S3}{S{3}^{\′}}---\left(7\right)$

${\mathrm{\μ}}_{{X2}^{\′}}=\frac{S4}{S{4}^{\′}}---\left(8\right)$

Table 1 fission neutron logging instrument actual measurement water correction factor

According to the data in table 1, can draw matched curve, as shown in Figure 2, taking water layer thickness as abscissa, water correction factor is ordinate, and then obtains fitting formula, i.e. formula (5) and (6).

Step 3, obtain after tested WIH correction along borehole axis neutron count rate SS1 according to formula (9); After obtaining tested WIH correction according to formula (10), depend on borehole wall neutron count rate SS2;

SS1=DS1·μ _X1 （9）

SS2=DS2·μ _X2 （10）

The epithermal neutron life-span that step 4, fission neutron logging instrument record is with to be rich in the degree of uranium in rock relevant with the degree of porosity of rock, is the accurate uranium content in computing rock, need be to being carried out the correction of epithermal neutron life-span by neutron count rate in well logging; According to formula (11) obtain by well logging in the epithermal neutron life-span revise after along borehole axis neutron count rate CS1; Obtain by the epithermal neutron life-span in well logging and revise the rear borehole wall neutron count rate CS2 of leaning on according to formula (12);

$\mathrm{CS}1=\mathrm{SS}1\·\frac{{\mathrm{\τ}}_0}{{\mathrm{\τ}}_1}\·\frac{e^{(-192/{\mathrm{\τ}}_0)}}{e^{(-192/{\mathrm{\τ}}_1)}}---\left(11\right)$

$\mathrm{CS}2=\mathrm{SS}2\·\frac{{\mathrm{\τ}}_0}{{\mathrm{\τ}}_1}\·\frac{e^{(-192/{\mathrm{\τ}}_0)}}{e^{(-192/{\mathrm{\τ}}_1)}}---\left(12\right)$

In formula:

CS1 and CS2 unit are s ^-1;

τ ₀---the epithermal neutron life-span recording in fission neutron logging module standard set-up, μ s;

τ ₁---the epithermal neutron life-span recording in tested wellhole, μ s.

The correction of neutron monitor counting rate, the correction of water correction factor and epithermal neutron life-span modification method in application the present invention, have positive effect:

(1) changed uranium ore gamma well logging in the past and can only indirectly calculate by surveying radium the well logging pattern of uranium, by applying modification method of the present invention, uranium content can be directly measured in fission neutron well logging, and with the comparison of drill core sampling chemical analysis results, deviation is no more than 10%.Modification method of the present invention provides technical support for directly surveying uranium fission neutron well logging technology in China's uranium exploration application;

(2) apply fission neutron well logging result of the present invention and more objectively reacted uranium ore grade, especially in the destroyed location of uranium radium balance, in conjunction with conventional γ-ray logging, can in-situ determination the uranium radium coefficient of balance of boring ore deposit section, reduced boring sample quantity, reduced uranium resource and reconnoitre cost;

(3) apply fission neutron of the present invention well logging modification method can Measurement accuracy mining using leaching technology in uranium leaching rate; avoid in mining using leaching technology process because of environment pollution and cost waste that blindly excessive fluid injection causes, to improve soak adopt smelting efficiency, reduce costs, protection of the environment has important practical significance.

Claims (2)

1. a fission neutron logging instrument calibration correction method, is characterized in that: comprise the following steps:

Step 1, obtain the correction counting rate of neutron monitor in tested wellhole

Neutron count rate S1 and S2 while gathering respectively in tested wellhole along borehole axis with by the borehole wall by fission neutron instrument, and the difference △ M of two neutron monitor MON1 of fission neutron instrument and the neutron count rate of MON2 record while gathering respectively in tested wellhole along borehole axis with by the borehole wall ₁with △ M ₂; In fission neutron logging module standard set-up, gather respectively along borehole axis and when the borehole wall difference △ M of two neutron monitor MON1 of fission neutron instrument and the neutron count rate of MON2 record ₀with △ M ₀ ^';

Neutron monitor correction neutron count rate DS1 and DS2 while obtaining respectively in tested wellhole according to formula (1) and (2) that neutron monitor is along borehole axis with by the borehole wall;

$\mathrm{DS}1=S1\·\frac{{\mathrm{\ΔM}}_0}{{\mathrm{\ΔM}}_1}---\left(1\right)$

$\mathrm{DS}2=S2\·\frac{{\mathrm{\ΔM}}_{0^{\′}}}{\mathrm{\Δ}{M}_2}---\left(2\right)$

Step 2, obtain water correction factor

1, gather the diameter D of tested wellhole _k, fission neutron logging instrument test tube diameter D _t, obtain according to formula (3) tested wellhole inwall and described fission neutron logging instrument test tube outer wall between clear water situation under water layer thickness d;

$d=\frac{1}{2}(D_k-D_T)---\left(3\right)$

2, obtain containing the equivalent water layer thickness d ' in mud situation according to formula (4),

In formula, d ' is the equivalent water layer thickness of well liquid, mm;

ρ _sandby gritty density in mud, g/cm ³;

ρ _mudfor mud balance, g/cm ³;

ρ _waterfor density, g/cm ³;

3, according to formula (5) obtain after fission neutron well logging alignment along borehole axis water correction factor μ _x1; According to formula (6) obtain after fission neutron well logging alignment by borehole wall water correction factor μ _x2;

μ _X1=0.7643e ^0.0200d' （5）

μ _X2=0.8761e ^0.0124d′ （6）

Step 3, obtain after tested WIH correction along borehole axis neutron count rate SS1 according to formula (9); After obtaining tested WIH correction according to formula (10), depend on borehole wall neutron count rate SS2;

SS1=DS1·μ _X1 （9）

SS2=DS2·μ _X2 （10）

Step 4, according to formula (11) obtain by well logging in the epithermal neutron life-span revise after along borehole axis neutron count rate CS1; Obtain by the epithermal neutron life-span in well logging and revise the rear borehole wall neutron count rate CS2 of leaning on according to formula (12);

$\mathrm{CS}1=\mathrm{SS}1\·\frac{{\mathrm{\τ}}_0}{{\mathrm{\τ}}_1}\·\frac{e^{(-192/{\mathrm{\τ}}_0)}}{e^{(-192/{\mathrm{\τ}}_1)}}---\left(11\right)$

$\mathrm{CS}2=\mathrm{SS}2\·\frac{{\mathrm{\τ}}_0}{{\mathrm{\τ}}_1}\·\frac{e^{(-192/{\mathrm{\τ}}_0)}}{e^{(-192/{\mathrm{\τ}}_1)}}---\left(12\right)$

In formula:

CS1 and CS2 unit are s ^-1;

τ ₀---the epithermal neutron life-span recording in fission neutron logging module standard set-up, μ s;

τ ₁---the epithermal neutron life-span recording in tested wellhole, μ s.

2. according to fission neutron logging instrument calibration correction method claimed in claim 1, it is characterized in that: described formula (5) and formula (6) obtain by the following method:

In order to measure the water correction factor of different pore size, build the uranium content building blocks logging module of test use, its physical dimension is 3.5m × 1.5m × 1.7m, aperture is 0.3m, the high 0.6m of base, top cover 0.4m, uranium ore section thickness is 0.7m;

In building blocks model wellhole, put into the ferule of different-diameter and sealed bottom, ferule diameter is within the scope of 79mm～259mm, select the ferule of 6 diameter values, measure injected water front and back in ferule and, along neutron count rate S3 and the S3' of borehole axis, calculate actual measurement along borehole axis water correction factor μ by formula (7) _x1 ^'; Same, measure the neutron count rate S4 and the S4' that in ferule, before and after injected water, lean on the borehole wall, calculate actual measurement by borehole wall water correction factor μ by formula (8) _x2 ^'; Concrete data are in table 1;

${\mathrm{\μ}}_{{X1}^{\′}}=\frac{S3}{S{3}^{\′}}---\left(7\right)$

${\mathrm{\μ}}_{{X2}^{\′}}=\frac{S4}{S{4}^{\′}}---\left(8\right)$

Table 1 fission neutron logging instrument actual measurement water correction factor

According to the data in table 1, draw matched curve, and then obtain formula (5) and (6).