SU1583900A1 - Method of seismic prospecting - Google Patents

Abstract

The invention relates to the field of seismic exploration with pulsed sources of excitation and can be used in geological mapping, prospecting of mineral deposits, as well as in engineering and construction exploration. The purpose of the invention is to increase the depth of intelligence by increasing the signal-to-noise ratio. The method produces two pulsed excitations of a seismic wave with a known interval within 3-4 periods of the excited signal, and filtering is performed by multiplying the seismic signal at the current time with the seismic signal delayed by the excitation interval, after their dynamic compression. 3 il.

Description

The invention relates to seismic exploration with pulsed sources of excitation and can be used in geological mapping, prospecting of mineral deposits, as well as in engineering and construction explorations.

The purpose of the invention is to increase the depth of seismic surveys by increasing the signal-to-noise ratio.

Figure 1 shows a block diagram of an analog seismic channel for the implementation of the proposed method for processing and recording received seismic information; in FIG. 2, input received and output (recorded) seismic traces;

Fig. 3 shows a pulsed excitation device for carrying out the proposed method in the exploration of small depths.

The block diagram contains seismic receiver 1, amplifier-compressor 2, block 3 delays, first 4 and second 5 quadruple multipliers, amplifier-decompressor 6.

Seismic receiver 1 is serially connected to amplifier-compressor 2, the output of which is connected to the input of the delay unit 3 and to the first input of the first four-square multiplier 4, the output of the delay unit 3 is connected to the second input of the first four-quadrant multiplier 4 and the second input of the second four-quadrant

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multiplier 5, the first input of which is connected to the output of the first four-quadrant multiplier 4, and the output - to the input of the amplifier-deco-spring 6, the output of which is connected to the recorder,

Seismic signal 7 is at the input of amplifier-compressor 2, signal 8 at the output of amplifier-compressor 2, time interval 9 between impulse effects, signal 10 at the output of delay unit 3, time interval 11 of signal 8, equal to the time interval 9, the signal 12 at the output of the first multiplier 4, the signal 13 at the output of the second multiplier 5, the signal 14 at the output of the amplifier -decompressor 6, the first load 15 with a ring 16 for fastening the cable of the lifting device and direct flow 17, the second load 18 with reverse tide 19th

The method is carried out as follows:

at once.

On the area under study, the period is determined from the excitation signal from a single pulse action in order to

effects existed a signal in the zero phase (for a label of reflections), set the time interval 9 between impulse actions equal to from three to four periods of a single signal excited by a single signal0 Produced, for example, using a device (FIG. 3) excitement of two seismic signals impulse effects separated by a time interval. A double excitation signal at a predetermined interval of 9 in the device (Fig. 03) is determined by the height difference of dropping weights 15 and 18. The seismic signals excited by two pulsed influences are received by seismic receiver 1 as an electrical signal 7 and are fed to the input of amplifier-compressor 2, having, for example, logarithmic transfer characteristic. In amplifier-compressor 2, seismic signals are dynamically compressed (compressed),

From the output of amplifier 2, the signal 8 is fed to the second input of the first four-quadrant alternator 4 and to the input of the delay unit 3, in which

seismic signals are delayed by a time interval 11 equal to the time interval 9 "The signal at the output of block 3 delays corresponds to signal 10, then the signal K from the output of amplifier-compressor 2 is multiplied (detected) with signal 10 in the first four-quadrant multiplier 4 in real time C; at the output of multiplier 4 will correspond to the signal 12 and in this form can already be used to isolate the first arrivals. Next, the signals from the output of the first multiplier 4 and the signal 10 from the block 3 of the delay arrive at the second multiplier 5, working as a phase demodulator, where they again multiply together and form a signal 13, which is fed to the input of the amplifier-decompressor 6, which produces amplification decompressing the signal 13 according to the law inverse to the law of dynamic compression. Compression and decompression of signals are used in the method in order not to distort the dynamic characteristics of the signals in analog signal processing in real time. Signal 14 at the output of decompressor 6 is recorded and used for interpretation. Due to the fact that double excitation is used with a set time interval of three to four periods of the excited signal, as well as compression and multiplication procedures are applied to the signal, the useful seismic signals in signal 14 have an increased signal-to-interference ratio. This helps to increase the depth of seismic surveys.

Claims (1)

Invention Formula A method of seismic exploration based on the excitation of seismic signals by two impulse effects separated by a time interval, reception and recording, which is similar to the fact that, in order to increase the depth of research by increasing the signal-to-noise ratio, the time interval between impulse effects set equal to from three to four periods of the excited signal, and the amplitude values of the received signal are dynamically compressed, delayed by a certain amount of time between pulses, the value of the delayed person. the signa multiply in the current time 83900 with the value of the unused signal, and the product is multiplied with the values of the delayed signal, thus formed, the signal is amplified according to the law, the opposite of the dynamic compression law, and register ufti 8 vwvy / l ten L Il V l / 12 4mL / J P 1 / b / WWH PERSONNEL ".jAiyv W" - n / VV, "... Fig 2 Fig 3