SU1442954A1 - Method of seismic survey - Google Patents

Abstract

This invention relates to the field of seismic acoustic research. The goal is to increase the reliability of the method by increasing the ratio of the useful signal: interference. For this, the elastic waves excite successively at n equally spaced points on a profile of length p / 2, register them at one point, the first point of excitation coincides with the point of reception, and the recorded records are summed up. I il.

Description

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The invention relates to seismic-acoustic studies and can be applied to study the structural structure of geological sections using the method of reflected waves (MOB), starting from the first meters, under conditions of intense regular and random interference waves with various kinematic characteristics.

The purpose of the invention is to increase the reliability of the method by increasing the ratio of the useful signal: regular interference.

The drawing shows a block diagram of a device for implementing the method

The diagram shows the emitter 1, the piezoceramic receiver 2, the pre-booster 3, the analog-digital unit 4, the magnetic recording unit 5, the analog recorder 6 and the torque-pickup sensor 7.

. The method is carried out as follows.

The elastic oscillations successively excite the emitter 1 at different times at several points of a linear profile equally spaced from each other, the length of which is equal to half the length of the longitudinal oscillation wave Lp / 2. Oscillations propagating in the medium register and transform the piezoceramic receiver 2 into electrical signals that enter the input of preamplifier 3. Amplifier 3 has a set of filters performing frequency selection, linear and software gain control. From the output of amplifier 3, signals are input. analog-to-digital unit 4, where it is converted from analog to digital form, summarized with the previous ones. and write to the random access memory, which is part of the analog-digital unit 4. From the random access memory, the information is cyclically extracted and displayed in analog-digital form on the display, also included in the analog-digital unit 4. On the display They visualize the process of accumulating information and measure the kinematic and dynamic characteristics of the signals. From the random access memory, the information can be copied in analogue form to the electrodynamic paper on the recorder 6, and

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in digital form - on a magnetic tape in block 5,

The method effectively attenuates random and regular wave-noise and at the same time enhances the reflections, the approach directions of which lie near a plane orthogonal to the profile. Moreover, the method allows to increase the signal: interference ratio to a significant value (everything is determined by the amount of random access memory), t, e. it becomes possible to emit very weak reflections.

Claims (1)

The method makes it possible to apply the method of reflected waves to investigate the depths, starting from the first meters, while the known methods allow investigations of MOBs from a depth of 80-100 mb. In addition, the proposed method is at the same time a method of recognizing reflected waves, since, by controlling the summation process, it is possible to track where in the seismogram the signal is constantly accumulating — this signal will be the reflected signal. This makes it possible to judge the presence of reflecting boundaries from a single observation point, which makes it possible to increase the efficiency of research. Invention Formula The method of seismic exploration by the method of reflected waves, which consists in the sequential excitation of elastic oscillations along a linear profile, the conversion of elastic oscillations by receivers into electrical signals, frequency selection, single-channel recording, summation and control of the summation process, which is due to the increase in the ratio of the useful signal: interference, elastic oscillations excite at least two equal points one from another ofil, extent of which is equal to half the wavelength of longitudinal oscillations dpiny p / Trich point positioning receiver coincides with the first point of excitation and subsequent paragraphs excitation removed from. Ar Receiver at a distance xt z. (, n-i) where K is the number of the point of entry; К О, 1,2 ,, .., п-1, where n is the number of points of excitation.