SU894635A1 - Geophysical survey method - Google Patents

Description

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This invention relates to geophysical survey methods.

The known method of geophysical prospecting, based on the use of the seismoelectric effect, in which, in order to increase the efficiency, the amplitude of the seismoelectric effect signal is measured in a constant electric field. CllUsing this method does not allow to determine the coordinates of the quartz core.

The closest to the present invention is a method of geophysical prospecting by taking oscillograms of elastic and electrical oscillations occurring in rocks under the action of artificial losses, in which, in order to determine the distance from the quartz core to the production wall, the velocity of elastic waves is measured. and registering the time from the moment of explosion until the arrival of the electromagnetic wave to the receiver, and the distance is calculated by multiplying this period of time by the speed of propagation of elastic waves (2.

However, the known methods have a very low efficiency, since they can only determine the distance from the explosion point to the object, but at its coordinates, especially if the object is local and located away from the bottom.

The purpose of the invention is to increase labor productivity by obtaining additional information about the coordinates of the object.

The goal is achieved by the fact that S is a known method of geophysical prospecting, based on the removal at the point of observation of oscillograms of elastic and electrical oscillations that occur in rocks under the action of artificial stress, measuring the velocity of propagation of elastic waves: registering the BpeMeHTf gap from the moment of explosion until the arrival of the electromagnetic wave to the receiver and the calculation of the distance to the object by multiplying this time by

Claims (2)

25, the velocity of elastic waves, additionally measure the induced emf at adjacent, equal in size bases located on the wall of the mine, i determine the point of maximum value of induced emf and distance from the point of explosion to the object and to the point of maximum value of induced emf about the location of the object. The method is implemented as follows. Along the wall of the excavation, pairs of receiving electrodes are placed at a certain distance from each other, which are connected to a multichannel recorder with a large input resistance. A seismic receiver recording the moment of the explosion is connected to one of the channels of the recorder. An excited elastic wave, reaching the electromyage of the rock (object), induces in it an electromagnetic igulus, which, spreading in all directions, induces the emf on the receiving electrodes. The magnitude of this emf depends on the propagation conditions of the electromagnetic wave along the beam connecting the object to the receiving points. Since the attenuation coefficient in a limited area of a quasi-isotropic rock massif varies slightly, the emitted emf at the electrodes depends mainly on the distance between the receiving pairs of electrodes and the object, and the larger the smaller the distance. The object's coordiat1a1 is determined by the rasterization from the point of explosion to the object (hypoteai), equal to the occurrence of the propagation of elastic waves in the medium for the period from the moment of explosion to the arrival time of the electromagnet wave, and from the point of explosion to the point with the maximum value induced emf (catheta). The performance of the method was tested in rocks with a damping of about 1 kHz (0.9 dB / m). The location of the quartz lens located at a distance of 90100 m from the working area is determined. Measured were carried out with a eight-channel apparatus. The receiving electrodes were installed in vertical holes filled with salt water. The distance between the pairs of receiving electrodes was taken from the correlation condition of the wave and I was 6 m. In total, seven pairs of receiving electrodes were installed, connected using equal length of shielded cable and recording equipment. To the eighth channel of the equipment, the seismic signals of the moment of the explosion were connected. The excitation of an elastic wave was carried out by the explosion of 100 g of explosives in a depth of 2 m. The obtained magnetograms were rewritten using a light-beam oscilloscope. Using the time interval from the moment of the explosion until the arrival of the electromagnetic wave and the speed of propagation of elastic waves, obtained by ultrasound, measured on the oscillogram, the distance from the point of explosion to the quartz lens was determined. Then, using a magnetogram, using a integrating voltmeter, a pair of electrodes was determined with the maximum value of the induced emf and, finally, the location of the quartz lens was determined from the point of explosion to the object and the pair of electrodes with the maximum value of the induced emf. The application of the method in fields with lower impedance rocks will be even more efficient, since, for example, the attenuation of electromagnetic waves at a frequency of 1 kHz is: for coal 3.4 dB / m, mud for 1.8 dB / m, ore 7.5 dB / m and so on. d. The proposed method of geophysical prospecting significantly increases the efficiency of searching for objects using seismoelectric and piezoelectric prospecting methods, reduces the costs of drilling and blasting, and allows the object to be located by a single explosion. As an additional advantage of the method, it should be noted that the electromagnetic wave, by virtue of its great length, is not sensitive to different and local structural heterogeneities that can be in the way of its propagation from the object to the receiving electrodes. The invention method of geophysical prospecting by means of observation at the point of observation of oscillograms of elastic and electrical oscillations arising in rocks under the action of artificial stress, measuring the velocity of propagation of elastic waves, recording the time interval from the moment of explosion I to the time of arrival of the electromagnetic wave to the receiver and calculating the distance nor to an object by multiplying this time by the velocity of elastic waves, characterized in that, in order to increase labor productivity, additional measurements are made erate emf in adjacent, equal in magnitude to the wall bases generation, determined point of the maximum value of the induced electromotive force and the distance from the shot object IO and to a point of maximum 5894635 & the values of the induced emf are judged by the locality 1. USSR author's certificate on the positioning of the object. K 494713, cl. G 01 3/00, 1976. Sources of information, 168812, CL. 6 01 V 3/08, 1965 taken into account in the examination (prototype). 2. USSR author's certificate