SU130193A1 - The method of recording seismic vibrations - Google Patents

Description

..f -1 fi, o

BSiS2 (T) SOFTWARE

If we divide the value of the function obtained for a particular value of m by the value of the function with m 0, then we obtain the normalized function:

Bs sa w

B5, S,

(one)

- cos -

2

- cos

№ 130193

As can be seen from formula (2), the values of the normalized function depend only on the phase of oscillation and do not depend on the amils.

The cross-correlation function has a remarkable noise immunity property, which is manifested in the fact that for coherent oscillations it has a certain value, and for interference, which is mostly incoherent, the value of the function is close to zero.

It is known that explosions and earthquakes are oscillatory processes containing many coherent components (reflected and refracted waves), while on the record before and after the explosion, the oscillations constituting the disturbances have the character of completely incoherent oscillations.

The second property of the cross-correlation function is that the registration based on the values of the function carries with it phase information, which is not lost at an arbitrarily small sweep rate of the oscillatory process over time.

Finally, the third property of the correlation function is the ability to determine the lengths of the wave (A) and the speed (s) of the recorded oscillations directly from the function values, which follows from formula (2), which can be rewritten in the form:

Bs, S :. (t) dx

     COS "-COSio (3).

Bs, S., (O)

In the block diagram of the correlation seismic recording channel, the π / 2 and positions are denoted by seismo-rhyemic; 3 and 4 amplifiers; 5 - Orthodox; 6 - integrating cell; 7 - oscilloscope galvanometer. Seismic receivers, amplifiers and galvanometers are the usual links of a conventional seismic recording channel (with amplitude recording).

To automatically obtain correlation fictions, the control system must perform two operations; multiplication and integration, so the multiplier and the integrating cell are included in each correlation channel.

To obtain a normalized correlation correlation, we need two correlation seismic recording channels. Two seismic sources of one of the channels are set so that the line, their connection (receiving base), the perpendicular profile line (direction

on the explosion); with such an arrangement, its receivers t f and

the galvanometer on the output of this channel registers BsiS2 {0). Both seismic receivers of the other channel are located along the profile at a distance from each other and a galvanometer at the output of this channel is recorded by BstSzir).

The normalized function is determined by the ratio of the deviations of the galvanometers at the output of both channels. The distance between its regularity Dh is selected depending on the rate of propagation of the V and the frequency of the recorded oscillations.

Thus, in order to obtain the normalization function of the seismic oscillations mutual correlation, a correlation system consisting of two seismic recording channels is necessary. However, for greater accuracy in determining K and v, and for solving some other problems of seismometry, a multi-channel system is used, one of the channels of which is intended for obtaining BsiS2 (0), and the others register BsiS2 {r) at various Dx values.

Dx „