CN103645512A - Multilayer ponding goaf detection method - Google Patents

Abstract

The invention discloses a multilayer ponding goaf detection method. The method comprises the following steps that according to geological data of a measured area and coal seam mining records, a measuring line is designed, and the measuring line passes through different numbers of layers, wherein a goaf section without ponding is included; according to a measurement area geology and electric logging data, a vertical electrical resistivity is calculated; according to estimated observation time, an induced electromotive force is measured along the measuring line; actual measurement curves of measuring points on one measuring line are drawn in one graph so as to form a curve family and shapes changes are compared; according to the measurement area geology, a?formation resistivity and a thickness in the electric logging data, coal mining records and determines an initial parameter of curve fitting quantification inversion, and a true resistivity and the thickness of a stratum are obtained after the inversion; the true resistivity and the thickness of the inversion stratum are drawn into a resistivity-depth profile map, then a result is explained according to qualitative deduction, a ponding goaf area is divided according to the electric logging or the sampled and measured true resistivity of the ponding which is taken as a threshold scope and quantitative deduction and interpretation are performed. By using the method of the invention, multilayer and low resistivity layer detection can be realized. The method can be applied in multilayer ponding goaf detection.

Description

A kind of multilayer ponding Mined-Out Areas method

Technical field

The invention belongs to electricity and electromagnetic prospecting field, be specifically related to a kind of time domain transient electromagnetic detecting technology.

Background technology

When colliery from superficial part to the layer-by-layer mining of deep, the safety in production in goaf, upper strata ponding Hou Jiangdui lower floor coal seam forms and works the mischief.Multilayer ponding Mined-Out Areas is the new task of coalfield-hydrogeology exploration, need to, on single low resistivity zone Detection Techniques [1-3] basis in the past, develop multilayer ponding Mined-Out Areas technology.

Documents

[1]KaufmanAA,KellerGV.1983.Frequencyandtransientsoundings.NewYork:ElsevierScience?PublishingCompanyInc.,338-350

[2] the flourish .1990. electromagnetic sounding of Piaoization method principle. Beijing: Geology Publishing House, 107-111

[3] Wang Zhanjun, Zhu Ziqiang, the resolution characteristic research of the .2012. transient electromagnetic methods such as Li Jianhui to low-resistance film. Geophysical-chemical computing technique, 34 (6): 646-651

Summary of the invention

The object of the present invention is to provide a kind of multilayer ponding Mined-Out Areas method, central loop TEM Detection Techniques are surveyed from single low resistivity zone, develop into multilayer low resistivity zone and survey.The technical scheme adopting is as follows:

The detection method in multilayer ponding goaf, is characterized in that comprising the following steps:

Step 1, according to surveying district's geologic information and seam mining record design survey line, makes survey line pass the different numbers of plies, comprises without location, ponding goaf;

Step 2, according to surveying district's geology and electric logging data, utilizes formula (1) to calculate longitudinal resistivity ρ _n

${\mathrm{\ρ}}_n=\frac{\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{\mathrm{\ρ}}_i{h}_i}{\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{h}_i}---\left(1\right)$

In formula, n is the stratum number of plies, ρ _iand h _ibe respectively thickness and the resistivity of i layer the earth;

Recycling formula (2) estimation observation duration T

$T={\mathrm{\δ}}_{\mathrm{TD}}^2\frac{4{\mathrm{\μ}}_0}{{\mathrm{\ρ}}_n}---\left(2\right)$

δ in formula _tDfor the maximum probe degree of depth, μ ₀=4 π * 10 ^-7permeability of vacuum as non magnetic the earth magnetic permeability;

Step 3, measures induced electromotive force emf according to the observation duration T of estimation along survey line;

Step 4, multilayer ponding goaf is explained in qualitative deduction: by the actual measurement emf Drawing of Curve of each measuring point on survey line forming curves bunch in same figure, the relatively variation of form, curve lifting represents that the ponding number of plies increases, curve decline represents that the ponding number of plies reduces;

Between described curve, lifting or decline are differentiated with following separation degree formula (3)

$d_i=\frac{2|{\mathrm{emf}}_{\mathrm{ki}}-{\mathrm{emf}}_{\mathrm{li}}|}{({\mathrm{emf}}_{\mathrm{ki}}+{\mathrm{emf}}_{\mathrm{li}})}\×100\%---\left(3\right)$

D in formula _ibe the separation degree between described two curves in i time road, emf _kiand emf _lisubscript in i represent i time road, k, l indicate respectively k lamination water and l lamination water;

Then calculate the average observed error of described two curves

$\stackrel{\‾}{e_i}=\frac{e_{\mathrm{ki}}+e_{\mathrm{li}}}{2}---\left(4\right)$

In formula

the observational error mean value that represents i time road, if

$d_i\≥3\stackrel{\‾}{e_i}---\left(5\right)$

Can think and between described two curves, have the variation of form, have the variation of the ponding goaf number of plies; Otherwise,

Think and between described two curves, there is no the variation of form, ponding goaf does not have the variation of the number of plies;

Step 5, quantitatively infer and explain multilayer ponding goaf: establish stratum number of plies n and equate with the time road number of actual measurement emf, according to formation resistivity and the thickness surveyed in district's geology, electric logging data, the initial parameter of quantitation using curve fitting method inverting determined in seam mining record, after inverting, obtain true resistivity and the thickness on stratum, the poor e of matching of each measuring point for quantitation using curve fitting method inverting quality _fevaluate e _f≤ 15% represents that matching quality is good, 15% < e _f≤ 25% represents matching Medium quality, e _f> 25% represents that matching is second-rate;

Step 6, is depicted as described For Solving The Resistivities of The Earth and thickness after resistivity-depth section figure, according to the qualitative deduction explanation results of described step 4; According to the ponding true resistivity of electric logging or sampling and measuring, be threshold range product of partition hydromining dead zone again.

If because restriction survey line in exploration place cannot pass through the different locations of ponding situation, when formula in step 4 (5) is false, ponding goaf does not have the variation of the number of plies, but does not represent there is no ponding goaf.

In the time cannot passing through the different location of ponding situation because of exploration place restriction survey line, utilize in claim 1 described step 1, two, three and step 6 described in electric logging or the ponding true resistivity of sampling and measuring determine ponding goaf for threshold range.

The present invention has beneficial effect.The present invention, by the center line loop line TEM Detection Techniques to low resistivity zone sensitivity, surveys and has developed into the detection of multilayer low resistivity zone from single low resistivity zone; By the comparison of separation degree between curve and observational error mean value, differentiate abnormal that multilayer ponding goaf causes, can be generalized to the abnormal differentiation of other geologic objective bodies; Get the stratum number of plies and the curve inverting that observation data time road equates, can obtain inverted parameters matrix true value solution, eliminate the redundant information that exists correlativity to produce between parameter, form resistivity-depth section that longitudinal fine degree equals time road number; According to ponding true resistivity, be the relative low-resistance product of partition hydromining of basis dead zone, threshold range product of partition hydromining dead zone, make to infer that explanation results more has determinacy.

Accompanying drawing explanation

Fig. 1 is that the present invention reaches the comparison diagram between cunette field with "nine squares" L185 line actual measurement emf curve; Transmitting loop length of side L _t=600m, receiving coil equivalent area S _r=100m ², observation in 200m * 200m region in the middle of the transmitting loop, measuring point spacing 20m, in figure the 940,1240,1260,1540,1560, the 1860th, survey period.

Fig. 2 is that the present invention reaches the resistivity-depth section figure forming after the curve inverting of cunette field with "nine squares" L185 survey line; In figure, ordinate is elevation, and horizontal ordinate is that survey period is also distance, and measuring point spacing is 20m as mentioned above.

Embodiment

Below in conjunction with the drawings and specific embodiments, technical scheme of the present invention is described in further details.

By mining area, Datong, reaching cunette field with "nine squares" multilayer ponding Mined-Out Areas is example.The Jurassic systerm in field with "nine squares" is main coal-bearing series greatly on the same group, has 2#, 7#, 8#, 11#, 12#, 14# coal seam to adopt.Seam mining records and shows, goaf is mainly distributed in 2#, 8#, 11# coal seam wherein, and each layer all has ponding possibility.Adopt central loop TEM method, transmitting loop length of side L _t=600m, receiving coil equivalent area S _r=100m ², observation in 200m * 200m region, transmitting loop center.The instrument adopting is the V8 multifunction electric magnetic method instrument of Canadian Phoenix company.

1. according to surveying district's geologic information and seam mining record design survey line, make survey line pass the different numbers of plies, comprise the location without ponding goaf;

2. according to electric logging data shown in table 1, get the least favorable situation that sky ponding is all adopted in each coal seam, the known longitudinal resistivity ρ of application of formula (1) _n≈ 96.33 Ω m, together with the 323m of depth capacity shown in table 1, in substitution formula (2), estimation place observation duration is T ≈ 5.4ms.Last time road of the high emission frequency 25Hz of V8 instrument is 7.1025ms, selects the transmission frequency of V8 instrument can meet the requirement of investigation depth.

Table 1 Datong Mine Area reaches the electric logging data on stratum, cunette field with "nine squares" ^*

^*getting coal seam, to adopt empty long-pending resistivity of water be 5 Ω m.

3. according to general electromagnetic survey technical regulation, along survey line, measure induced electromotive force emf;

4. the qualitative deduction in multilayer ponding goaf is explained.By the actual measurement emf Drawing of Curve of each measuring point on L185 survey line wherein forming curves bunch in a figure, as shown in Figure 1, the relatively variation of form.The actual measurement emf curve of visible L185 line has been divided into 3 bunches of interim lifting along the line: 940～No. 1240 points, 1260～No. 1540 points, 1560～No. 1860 points, show that the number of plies segmentation of ponding goaf increases, and every transition once increases one deck.In Fig. 1, curve is significantly along survey line variation, but still need to the separation degree between curve family, provide quantitative differentiation with formula (3)～(5).ERROR_BAR in actual observation record is observational error, and result is as shown in table 2.As seen from Table 2

think and between curve family, have the variation of form, the corresponding ponding goaf number of plies changes.

Separation degree list between the actual measurement emf curve family of table 2 survey line L185

5. the quantitative deduction in multilayer ponding goaf is explained.If stratum number of plies n equates to be 20 layers with the time road number of actual measurement emf curve, according to surveying district's geology, the electric logging data of table 1, seam mining record, determine inverting initial parameter: the group stratum, Yungang Grottoes of average thickness 110m is divided into 5 layers by original 4 layers so that adapt to 2# coal with overlying strata because degrading the variation in thickness causing in earth's surface; By do not adopt thinner 7 ^#, 12 ^#one deck is merged in coal and upper and lower rock stratum, occurs no longer separately; Variation in thickness larger 2 ^#coal still keeps original two-layer model, the situation that may be full of completely by ponding after adapting to the variation in coal seam itself and adopting sky.The initial parameter of quantitative inversion is in Table 3, and what curve inverting adopted is improved Using Generalized Matrix Inversion Method.The poor e of matching of each measuring point for curve inverting quality _fevaluate: 8% < e between 940～No. 1240 points _f< 12% is good, 12%≤e between 1260～No. 1540 points _f< 25% is medium, 25%≤e between 1260～No. 1540 points _f< 30% is poor.

Table 3 inverting initial parameter

Sequence number	ρ i/Ωm	h i/m	Sequence number	ρ i/Ωm	h i/m
						1	30	10	11	85	10
2	60	10	12	180	3
						3	70	20	13	110	34
4	80	30	14	85	20
						5	90	40	15	185	3
6	160	4	16	100	20
						7	180	5	17	110	10
8	80	20	18	200	2
						9	70	36	19	100	15
10	90	42	20	120	?

6. quantitative inversion result is depicted as to resistivity-depth section, as shown in Figure 2.

1. according to the qualitative interpretation result of described step 4, infer between 940～No. 1240 points not or have one deck ponding goaf between 1260～No. 1540 points, have one deck or two-layer ponding goaf, between 1560～No. 1860 points, there are two-layer or three lamination hydromining dead zones;

2. ponding true resistivity 1～20 Ω m measuring according to electric logging is threshold range product of partition hydromining dead zone: between 940～No. 1240 points, have one deck ponding goaf, between 1260～No. 1540 points, there is two-layer ponding goaf, between 1560～No. 1860 points, have or three lamination hydromining dead zones.

Reach cunette field with "nine squares" multilayer ponding Mined-Out Areas and there is no 7,8 situation.

Claims (3)

1. the detection method in multilayer ponding goaf, is characterized in that comprising the following steps:

Step 1, according to surveying district's geologic information and seam mining record design survey line, makes survey line pass the different numbers of plies, comprises without location, ponding goaf;

Step 2, according to surveying district's geology and electric logging data, utilizes formula (1) to calculate longitudinal resistivity ρ _n

${\mathrm{\&rho;}}_n=\frac{\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}{\mathrm{\&rho;}}_i{h}_i}{\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}{h}_i}---\left(1\right)$

In formula, n is the stratum number of plies, ρ _iand h _ibe respectively thickness and the resistivity of i layer the earth;

Recycling formula (2) estimation observation duration T

$T={\mathrm{\&delta;}}_{\mathrm{TD}}^2\frac{4{\mathrm{\&mu;}}_0}{{\mathrm{\&rho;}}_n}---\left(2\right)$

δ in formula _tDfor the maximum probe degree of depth, μ ₀=4 π * 10 ^-7permeability of vacuum as non magnetic the earth magnetic permeability;

Step 3, measures induced electromotive force emf according to the observation duration T of estimation along survey line;

Step 4, multilayer ponding goaf is explained in qualitative deduction: by the actual measurement emf Drawing of Curve of each measuring point on survey line forming curves bunch in same figure, the relatively variation of form, curve lifting represents that the ponding number of plies increases, curve decline represents that the ponding number of plies reduces;

Between described curve, lifting or decline are differentiated with following separation degree formula (3)

$d_i=\frac{2|{\mathrm{emf}}_{\mathrm{ki}}-{\mathrm{emf}}_{\mathrm{li}}|}{({\mathrm{emf}}_{\mathrm{ki}}+{\mathrm{emf}}_{\mathrm{li}})}\&times;100\%---\left(3\right)$

D in formula _ibe the separation degree between described two curves in i time road, emf _kiand emf _lisubscript in i represent i time road, k, l indicate respectively k lamination water and l lamination water;

Then calculate the average observed error of described two curves

$\stackrel{\&OverBar;}{e_i}=\frac{e_{\mathrm{ki}}+e_{\mathrm{li}}}{2}---\left(4\right)$

In formula

the observational error mean value that represents i time road, if

$d_i\&GreaterEqual;3\stackrel{\&OverBar;}{e_i}---\left(5\right)$

Can think and between described two curves, have the variation of form, have the variation of the ponding goaf number of plies; Otherwise,

Think and between described two curves, there is no the variation of form, ponding goaf does not have the variation of the number of plies;

Step 5, quantitatively infer and explain multilayer ponding goaf: establish stratum number of plies n and equate with the time road number of actual measurement emf, according to formation resistivity and the thickness surveyed in district's geology, electric logging data, the initial parameter of quantitation using curve fitting method inverting determined in seam mining record, after inverting, obtain true resistivity and the thickness on stratum, the poor e of matching of each measuring point for quantitation using curve fitting method inverting quality _fevaluate e _f≤ 15% represents that matching quality is good, 15% < e _f≤ 25% represents matching Medium quality, e _f> 25% represents that matching is second-rate;

Step 6, is depicted as described For Solving The Resistivities of The Earth and thickness after resistivity-depth section figure, according to the qualitative deduction explanation results of described step 4; According to the ponding true resistivity of electric logging or sampling and measuring, be threshold range product of partition hydromining dead zone again.

2. the detection method in a kind of multilayer ponding according to claim 1 goaf, it is characterized in that: if limit survey line because of exploration place, cannot pass through the different locations of ponding situation, when formula in step 4 (5) is false, ponding goaf does not have the variation of the number of plies, but does not represent there is no ponding goaf.

3. the detection method in a kind of multilayer ponding according to claim 2 goaf, it is characterized in that: in the time cannot passing through the different location of ponding situation because of exploration place restriction survey line, utilize in claim 1 described step 1, two, three and step 6 described in electric logging or the ponding true resistivity of sampling and measuring determine ponding goaf for threshold range.