SU1330597A1 - Method of geoelectric prospecting by means of stray currents - Google Patents

Abstract

The invention relates to geophysical methods of exploration of mineral deposits and can be used in geo-electrical exploration by the method of stray currents (BT). The aim of the invention is to improve the accuracy of research and the performance of field work using the BT method. This is achieved by making a simultaneous measurement of the field intensity with the help of two pairs of perpendicular base installations and field-oriented field installations, introducing a correction factor for the position of the source of the field and receiving installations, 3 sludge. From F W with 00 o ate (X

Description

The invention relates to geophysical methods of exploration of mineral deposits, namely, geoelectroprospecting by means of stray currents (BT).

U, invention of increasing the accuracy of research and productivity of field work by the BT method.

FIG. 1 shows a scheme for determining common vectors; FIG. 2 is a diagram for determining correction factors for field and basic installations; in fig. 3-. Results of laboratory works and 4ecKttx theoretical calculations for amending the uQ parameter; on the influence of the relative position of the source of the field and the observation points.

FIG. 1-3 marked; 1 — source-field, 2 — observation profile, 3 — projection of a well-conducting nonuniformity on the surface of water in the tank.

The method is implemented as follows.

Simultaneously, the BT field strengths are measured with two pairs, mutually perpendicular basis and profile-oriented observations, field installations, the location of the source pole is determined, and the correction factor (K) is calculated, which takes into account the relative position of the source and receiver settings. Pairs of mutually perpendicular basic facilities are located in the central part of the survey area at a distance of more than half a length of a linear-bipolar source from each other, along it and remain motionless until the end of the survey. Field installations have at the beginning of the first profile an interval equal to the observation step, with the front receiving line of each installation with the back line for the next installation. A simultaneous measurement of the voltage zero at all receiving installations is carried out. Then the field settings: and move to the second interval of this profile. After completion of the shooting, the first profile, transition to the second profile, etc.

For the moments of observations, at each station of receiving installations, systems are constructed for stress vectors

Ш1 basis settings,, Е i.jj и. Ец relative to average

C points between base points. The common vector (EORTS) is directed to the zero point of the linear-bipolar BT source, where there is no current exchange between the solutions and the environment ..

Know the place of contact of the negative pole of the traction network with the rails

and the zero point determines the location of the positive pole at the time of measurement.

. To calculate K, a linear-bipolar source is divided into l1.

elementary segments and consider it a system of point sources. The resistance ul of the source section (rail) is denoted by RP, the contact resistance is R. The total resistance of the section of the path, according to Kirchhoff’s laws, is defined by the formula

about - SjiiQiulSul- (1 R .. + 0, + К „У

 Q; ,, + R

,

ABOUT .

3Q where n is the number, L1 elementary

segments of the plot and. Current flowing into the ground from i-ro

source segment.

 35

l .r. (2) n (, + 2R,)

Qci

where I is the current of the current network.

The potential difference between the electrodes M and N of the receiving device at the location of the poles at the ends of the source is determined by the formula

TT P 1 -1

IE iA M

one

(3)

iN

0

where the expression is under the sum sign, W t + 1

VN

j-h

iH

to".

distance

receiving electrodes from the 1st segments of the sections of the path with positive and negative currents, p - specific 5 electrical resistance media.

From formula (3), we determine (the coefficient K ° at any position of the receiving device relative to a linearly bipolar source is shown).

We denote the coefficient considered for the observation installation-oriented first base unit napbi.Kg, the second base pair Kg, field installation K and

note that in a homogeneous environment

, Kn / 4, 5

uUn / i USx

(4) (5).

The parameter of studying the geoelectric structure is the ratio of the intensity of the field point to the intensity of the base point: point. Consequently, in order to introduce the considered correction to the parameter t (f. Follows it., Multiplied by ,, 4, / 4; K; 7.

Based on the foregoing, an averaged parameter is proposed; neither the floor BT:

vt

f1

To substantiate the advantages of this method, special laboratory-model studies were carried out in an electrolytic tank. The model of the VT source was a spiral of steel wire wound on a vinyl plastic pipe. The length and diameter of the wire is chosen so as to provide similarity with rails 2-3 km long. The source model is positioned horizontally in the tank at a depth of 5 cm. The negative contact of the universal power source (UTI) is connected to one end of the rail track model, the positive pole to points I-IV (Fig. 1). For the definition of common BeKTopoB jia two basis points, ah measure the E, E yj, P four-point contact positions of the positive pole. With respect to the midpoint C of the segment connecting the base points, four common vectors are constructed.

E

IV 06C

The latter, as shown

in fig. 1, are directed to the zero points of the source.

O

five

0

five

0

five

five

0

0

The U () / curves are characterized by a wide asymmetric maximum versus a linear-bipolar source and a local minimum over a well-conducting inhomogeneity. The asymmetry of the maxima is due to the location of the observation profile at an angle relative to a linearly bipolar source. From the divergence of the curves u (j, and u (j, taken at two basis points), it can be judged that the intensity of the anomaly of this parameter also depends on the position of the base installation.

Claims (1)

After the amendment to the effect of the mutual position of the source of the field and the observation points of the curve V V outside the limits of heterogeneity, is completely leveled. The anomalies over inhomogeneity become symmetrical and characterize the vertical fall of a well-conducting object. Formula invented and The method of geoelectroprospecting by the method of stray currents (BT), at which the intensity of the field of the BT is simultaneously measured with the help of two receiving installations, different in that, in order to increase the accuracy of research and the productivity of the field work, two base points and field points, with the base points being measured in perpendicular directions, and in the field point in the direction of the observation profile according to the field strengths BT of the base points in perpendicular the local directions determine the location of the positive pole of the source, calculate the correction coefficient of the relative position of the positive pole of the source and the observation point and then on the value of the product of the ratio of the field strengths of the BT field in the direction of the observation profile in the field and one of the base points and the ratio of correction factors the same basic and field points judge the geological structure of the environment. O-4-e- t.j, .. (y  I p X -eA „ about- -LN -0.75  | D5 / T -about Editor M.Dish Compiled by A.M. gkov Tehred M.Hodanich Order 3580/49 Circulation 730 Subscription VNISh of the USSR State Committee for Inventions and Discoveries 4/5, Raushsk nab., Moscow, 113035 Production and printing company, Uzhgorod, st. Project, 4 phyaz Proofreader A.T. sko