SU1312501A1 - Method of recording seismic signals - Google Patents

Abstract

The invention relates to seismic exploration and can be used in multichannel recording of seismic signals. The aim of the invention is to improve the signal to noise ratio in seismic records by eliminating monochromatic interference. The method is suitable for any value of the frequency of monochromatic interference. The interference frequency is determined during seismic operations. For this, a linearly varying signal is correlated with received noise and the frequency of interference is estimated from the correlation data. After that, a tunable notch filter is tuned to the interference frequency and the seismic code is recorded. 2 Il. i (L to SP

Description

113

The invention relates to seismic exploration and can be used for multichannel recording of seismic signals.

The purpose of the invention is to increase the signal-to-noise ratio by suppressing monochromatic interference.

Fig. 1 shows a block diagram of a device for implementing the proposed method; Fig.2 block diagram of the analyzer accuracy.

Each seismic channel contains a seismic receiver 1 connected via a seismic streamer 2 to the input of amplifier 3, the output of which is connected to a tunable notch filter 4. The inputs of the correlator drive 5 are connected to the outputs of amplifiers 3 of all channels and to the output of the reference signal switching circuit 6, the inputs of which connected to the generator 7 of the linearly varying frequency (LICH), to one of the outputs of the correlator-accumulator 5 and to one of the outputs of the precision analyzer 8, the other output of which is connected to the notch control unit 9 Filtering and an input accuracy zlizatora 8 connected to the second output of the correlator, an accumulator 5, a third viod which is connected with the control unit 9, notch filters 4,

The functional diagram of the precision analyzer 8 includes a digital-to-analog converter-10, a meter of 11 periods, a block 12 of the memory of period values, a block of 13 memory of a given period deviation from the average, a logical-arithmetic unit 14,

The method is carried out as follows.

In each channel, microseismic signals received by the seismic receiver 1 and induced on the seismic streamer 2 are transmitted through the seismic amplifier 3 to the correlating torus drive 5, to the other input of which the signal comes from the LICH generator 7 through the switching circuit 6 of the reference signal. The correlating drive-drive 5 correlates the received microseismic signals of all channels with the reference LICH, resulting in a monochromatic interference from the microseismic signals in each channel. Since the staff correlator of a vibroseis station can be used as a correlator of a torus, you

enumerating on the order of 2000 points of the correction function, a sufficient number of monochromatic noise periods can be distinguished.

The fi-loop correlator 5 sums the selected monochromatic interference of all channels, thereby improving the monochromatic interference / noise ratio, and provides the resulting mono signal

chromatic noise on the analyzer 8

accuracy. The precision analyzer 8 evaluates the accuracy of the monochromatic interference, for which it measures each period of the selected monochromatic interference, determines the average period and relative deviations of each period from the average, and compares the obtained relative deviations with those specified in advance. If the calculated relative deviations of the period of the monochromatic interference exceed a predetermined value, then the accuracy analyzer 8 issues the command

and the selected monochromatic interference through the reference signal switching circuit 6 is supplied to the correlator-drive 5 as a reference signal for correlation with the secondary

seismic receivers 1 micro

seismic signals of all channels.

The correlator-accumulator 5 re-sums the correlated signals of all channels, and the accuracy analyzer 8 again assesses the accuracy of the monochromatic interference. The operations of receiving microseismic signals, correlation, summation and

estimates of the accuracy of the monochromatic interference are made until, after an assessment of the accuracy, the calculated relative deviations of the period of the monochromatic interference do not exceed the predetermined time. In this case, the precision analyzer 8 issues a command to pass the selected monochromatic filters through the control unit 9

interference to the notch filters 4 to adjust them to the frequency of interference.

The accuracy analyzer unit 8 measures each period of a monochromatic interference disturbance, determines

the average period and the relative deviations of each period from the average compares the obtained relative deviations with the predetermined ones, depending on the result of the comparison

ten

issues the appropriate command to finish the signal processing or to further process it.

The functions of the precision analyzer 8 can be performed by a microprocessor computing system, and in the absence of it in hardware, the precision analyzer 8 can have a flowchart (figure 2), which works as follows.

The monochromatic interference signal is fed to the accuracy analyzer 8 from the memory of the correlator of the storage ring. After the digital-to-analog converter, the monochromatic interference signal is fed to the period meter, which measures each period of the monochromatic interference signal and sends it to the memory of the period values and then to the logic-arithmetic unit-20. The logical-arithmetic unit calculates the value of the average period, summing up all periods and producing a division by the number of periods, calculates the difference between each value of the period of monochromatic interference and the average period, and then compares the difference obtained with the specified value of the period deviation from the average stored memory, and depending on the result of the comparison, the corresponding command is issued to finish the signal processing or to further process it.

 T

-sr

X 100%: 1%.

If this condition is met, then the process of isolating monochromatic interference is terminated. Otherwise, the process of isolating monochromatic interference proceeds iteratively.

Tunable notch filter can be performed on the axis of the synchronous filter, where the switched capacitors with resistor 15 form the desired filter. A switching frequency proportional to the frequency of the selected monochromatic interference determines the frequency of the notch filter and its stability.

Claims (1)

Invention Formula 25 A method of recording seismic signals, including multichannel reception, amplification, filtering with notch filters and recording of seismic signals, characterized in that, in order to increase the signal-to-interference ratio by suppressing 30 monochromatic interference, microseismic noise is received in all channels, the signal of a linearly varying frequency in the frequency range of the seismic signal, the correl For example, Let the accuracy of 35 RU from a microsemiomic noise from a monochromatic interference signal with a linearly varying frequency, be no worse than 1%. Then, for the selected monochromatic interference, calculate the correlated signals for all channels measured each period, estimate the average period and the relative deviations of each period from the average, compare the relative deviation with the predetermined and iteratively repeat all signal processing procedures until the relative period deviation is reached. less than a prescribed value, then the notch filter tuned to each channel on the frequency is the average period, according to the formula P  I. eleven T- where T. is each period in the implementation of the selected monochromatic interference; n - the number of analyzed periods, to provide the required amount 45 summarize the procorrelated signals across all channels, measure each period, estimate the average period and relative deviations of each period from the average, compare the relative deviation with a predetermined set and iteratively repeat all signal processing procedures until the relative deviation of the period becomes less than the set deviation values, then adjust the notch filter in each channel to the frequency In order to render a monochromatic house - a monochromatic blockade, the conditions must be met.  T -sr X 100%: 1%. If this condition is met, then the process of isolating monochromatic interference is terminated. Otherwise, the process of isolating monochromatic interference proceeds iteratively. ten Tunable notch filter can be performed on the axis of the synchronous filter, where switched capacitors together with a resistor form the desired filter. The switching frequency, proportional to the frequency of the selected monochromatic interference, determines the frequency of the notch filter and its stability. Invention Formula The method of recording seismic signals, including multichannel reception, amplification, filtering with notch filters and recording of seismic signals, characterized in that, in order to increase the signal-to-noise ratio by suppressing monochromatic interference, receive microseismic noise in all channels, generate linear frequency signal over the seismic frequency band, correlating RF from microseismic noise with a signal of a linearly varying frequency, summarize the procorrelated signals across all channels, measure each period, estimate the average period and relative deviations of each period from the average, compare the relative deviation with a predetermined set and iteratively repeat all signal processing procedures until the relative deviation of the period becomes less than the set deviation values, then adjust the notch filter in each channel to the frequency