SU1444687A1 - Device for vibration seismic prospecting - Google Patents

Abstract

The invention relates to vibroseismic devices and allows to expand the field of application by providing the possibility of carrying out seismic surveys using a particular method. The input seismic signal received by the sensors is amplified and converted to digital samples having multiplexed form by a transceiver unit and fed to a vibroseis signal converter, which includes a reference signal generator, a driver for controlling pulses, a driver for frequency seismograms, and a random access memory. The frequency seismogram generator contains an input register, a multiplier, a low-pass filter and an output register, and performs a synchronous detection operation: multiplication of the seismic and reference signals of the linearly increasing frequency in the multiplier and low-pass filtering in the digital filter. The result of synchronous detection is the final sum of the samples of the frequency gather, and the summation number is determined by the period of the frequency gather. The values of the samples are stored in the random access memory and, after the end of the session, are automatically copied to the magnetic recorder, 8 s,:

Description

CX)

1 1444687 The invention relates to devices for vibro-seismic reclosures and can be used during seismic surveying by vibration methods, which are based on the determination of seismograms using the frequency response of the medium by Fourier transform,

The IGM 7 (FIG. 2) contains AND 14, series-connected circuits, one vibrators 15, 16, and 17, and the differential purpose of the invention is to expand Q (a 18 circuit, the first input

;

rhenium field of application of the device.

Figure 1 shows the structural diagram of the device for seismic exploration; Fig. 2 is a functional diagram of a driver driving pulses; FIGS. 3 and 4 show timing diagrams of operation of the control pulse generator in the Session and Overwrite modes; on fig.Z - functional diagram of the low pass filter; figure 6 - block diagram of the logic unit; figure 7 is a structural diagram of the transceiver unit; Fig. 3 is a functional diagram of a random access memory.

The device contains seismic sensors 1 connected to transceiver unit 2, connected by a second input to the first output of logic unit 3, the second output of which is connected to a magnetic recorder (MP) 4, and transducer 5 of vibrating circuit I 14 is connected respectively to R- and 3-in RS-flip-flops 19 and 20 and the Start input with kn, the second input with the R-input of the trigger 20 and with the input

5 one-shot 21, consistently

connected to the differentiating circuit 22, the output of which is connected with the S-input of the trigger 19 and the first input of the circuit 23 connected by the second input to

The 20 input of the one-shot 21 and the output to the R-input of the RS flip-flop 24, which is connected to the output of the one-shot 16, the input of which is connected by a differentiating circuit 25.

25 LPF 12 (FIG. 5) contains a series-connected adder 26, filter RAM 27, a RAM register 28, the output of which is connected to the first input of the filter register 29 and the second input

30 adder 26, and. also sequentially connected counter 30 addresses of seismic channels (ACK) and address selector 31, the output of which is connected to filter RAM 27, the second input from the output of counter 32 of the address of frequency channels (AChK), and the third input to the ACHK input 32 and the input of the register 29 of the filter.

roseismic signals, including the reference signal generator (GOS), shaper 7 control pulses (IGF), shaper 8 frequency seismograms (PSF) and random access memory (RAM) 9. GOS 6 is connected in series with IGF 7, the first output of which is connected with the input GOS b, the second output with the first control input of RAM 9, and the third with the control input of the block 3 of logic 1

The FPS 8 contains a serially connected input register 10, a multiplier 11, the second input of which is connected to the second output of GOS 6, a low-pass filter 12 and a output register 13 whose output is connected to the information input of RAM 9, and the control and the information inputs of the input register 10 are connected respectively to the control and information outputs of the transceiver unit 2, the first and second control inputs of the low-pass filter .12 are connected respectively to the second and third control inputs of the RAM 9 and the second and third outputs of the BL eye 3

7

logic, control input of the output register 13 is combined with the third control input of the low-pass filter 12 and the fourth control input of the RAM 9 and is the clock input of the device.

IGM 7 (FIG. 2) contains an AND 14 circuit in series, a single vibrator 15, 16 and 17 and a differential (dummy circuit 18, with the first input

And 14 circuits are connected respectively to the R- and 3-in of RS-flip-flops 19 and 20 and the Start input with kn, the second input with the R-input of the trigger 20 and with the input

one-shot 21, consistently

connected to a differentiating circuit 22, the output of which is connected to the S input of the trigger 19 and the first input of the AND circuit 23 connected to the second input

the one-shot input 21 and the output to the R-input of the RS flip-flop 24, which is connected to the output of the one-shot 16, the input of which is connected by a differentiating circuit 25.

The LPF 12 (FIG. 5) contains a series-connected adder 26, a filter RAM 27, a RAM register 28, the output of which is connected to the first input of the filter register 29 and the second input

adder 26, and. also connected in series are the counter 30 of the address of seismic channels (ACK) and the address selector 31, the output of which is connected to filter RAM 27, the second input is from the output of counter 32 of the frequency channels address (AChK), and the third input is with the ACP input 32 and the register input 29 filter.

Logic unit 3 (FIG. 6) contains recording records connected in series and intermediate register 33, RAM 34, and a buffer register 35, the second input of which is connected to the input of the playback control device 36, to the second input of the intermediate register 33, the output of the synchronizer 37 and the first input of the circuit 38 controlling the RAM of the recording whose output is connected to the second input of the RAM 34 of the recording. The second output of the synchronizer 37 is connected to the counter 39 channels, and the third output is connected to the write logic circuit 40, the second input of which is connected to the communication device 41.

Transceiver unit 2 contains serially connected pre-amplifiers 42, the switch 43 channels, the main amplifier 44 and the ADC .45,

RAM 9 (FIG. 8) contains the first address counter 46 and the second address counter 47 connected to the address switch 48, the output of which is connected to the memory 49, Counters 46 and 47 can be performed, for example, on integrated circuits of type K155IE4 and K155IE5, the switch 48 addresses - on K155LR1, and the storage device 49 - on 565 RU 3.

The device for vibroseismic works as follows.

When conducting seismic surveys using the frequency method, the device has two main modes of operation: Session mode and Overwrite mode. In Session mode, the vibrator excites seismic vibrations, receives and converts vibroseis oscillations into digital form, calculates the frequency seismogram and records it in RAM 9. The Overwrite mode overwrites the data of the frequency seismogram accumulated during the session in RAM 9 onto a magnetic tape MP 4. The need to pre-record field material first in RAM 9 is due to the fact that, when performing work using the frequency method, the duration of a session can reach 200-400 s, with this m useful information in the form of frequency seismogram is infranizkochastot- ny process whose spectrum lies in the frequency band from O Hz to, i.e. the amount of information of the frequency seismogram is approximately 100 times less than the amount of information of the input vibration seismic signals. Coordination of the data stream with the bandwidth of MP 4 requires buffering of the information array, which consists in accumulating frequency seismogram data during a session of 200-400 seconds, followed by a quick (2 hrs) overwriting of the accumulated array onto a magnetic tape. According to the Start signal from the switchgear (Fig. 3a), which is fed to the IGF 7 input, RS-triggers 19 and 20 and the uni-vibrator 15 are simultaneously triggered via the E14 circuit. The control starts up.

luch signals mode

on

The output of the F3Ttrigger 19 is formed by the Accumulation signal (FIG. 3.6), which

15

0

25

0

five

0

five

0

five

Topi comes to the block 3 of logic and translates the device into the standard operation mode with accumulation. At the output of the RS flip-flop 20, the signal On, reg, H (Fig. 3, c), the single state of which turns off the MP 4, is disconnected. Thus, in the Session mode, MP 4 does not work.

After 1s after pressing the Start button, the output of the one-shot 15fop fflpyetc signal, on the falling edge of which the one-shot 16 is triggered, and at the start of the 25th circuit 25, a start-up signal I is produced (Fig, 3). Through 3c, the signal from the output of the one-shot 16 starts the one-shot 17 and the RS-flip-flop 24, the output of which forms the Start H signal (FIG. 3, d), and on the code of the one-shot 17.-signal 0.5 second in length; the front of which by the diffraction chain 18 produces the NOM signal (Fig. 3, e).

The single-oscillators 15, 16, 17 and 21 can be performed, for example, on the basis of K155AHZ chips, each of which is a complete functional unit, with the exception of the master circuit time, the functions of which are performed by an external resistor and capacitor.

On the NOM signal, the STA 6 and vibration installations are simultaneously launched. The signals from the seismic receivers 1 are fed to the transducer unit 2, in which they are subjected first to pre-amplification and filtering, and then converted from continuous signals to discrete samples and their further digitization. The digital values of each sample, expressed by the binary parallel code, from the output of the transducer unit 2 are fed to the input of the FIS 8, the other input of which receives the values of the reference signal from the output of the OHS 6 ...

FIS 8 performs the operation of calculating a frequency seismogram, which consists in synchronous detection of a vibroseis signal by a reference signal, for which these signals are multiplied and low-frequency filtering of the multiplication result. Operf synchronization detection is described by the expression

A (t) Z.S (t) b (t)

where A (t) is the signal of the frequency gather;

S (t) seGyumic signal; b (t) is the reference signal; n is the number of summations needed to perform low-pass filtering.

The reference signal is an exact copy of the signal emitted by the vibrator; it is a signal with a linearly increasing frequency. The generator GOS 6 can be performed, for example, as a counter operating on overflow pulses of an accumulator of limited capacity.

The seismic signal received at the input of the PSF 3 for the duration of one channel is stored in input register 10, from the output of which multiplies 11 is input to which GOS 6 signal arrives to another input. Input register 10 and output register 13 can be executed, for example , on integrated circuits K561IR94 The multiplication of the seismic and reference signals is carried out in the multiplier 11, which can be executed, for example, on integrated circuits K561IP5 with direct links. The result of the multiplication is fed to the input of the low-pass filter 12. The low-pass filtering operation, performed digitally, is laborious as it requires significant hardware costs. However, the specific features of the frequency method allow the use of simple low-pass filters based on single-interval averagers, in which the output sample values are obtained by summing the input samples in the interval t of the action of the output samples.

The interval t of the output samples of the frequency seismogram is determined by the frequency "(c, -toro represents the sampling frequency of the frequency seismogram and is set by its upper harmonic, not exceeding 1 Hz for the actual parameters of the session. For this signal, the sampling frequency should not be lower than 2 Hz, in this case accepted

- pch 3, / Hz, i.e. interval

0

five

0

five

0

five

0

five

0

five

frequency,

The sampling rate is about 300 ms. Since the samples of input samples on each seismic channel are received after 2 ms, a little more than 150 samples of input vibroseismic signals are placed on the interval f of the output samples.

At the beginning of each summation segment, for example, zeros are recorded in the filter RAM 27 at the first channel address on the first seismic channel, so the previous summation result is erased from the filter RAM 27 cells on this channel. The first multiplication result from the output of the multiplier 11 is fed to the input of the adder 26 and is summed with the zero information read from the filter RAM 27, which is fixed in the RAM register 28. The summation result (the first sum) is recorded in the first cell of the filter RAM 27. The next value of the product for this channel is summed up with the first amount read from the filter RAM 27, and the result — the second amount — is written to the first cell of the filter 27. RAM at the address of the first channel. This operation is repeated to get the final sum result on first channel .. (150, input samples).

j Sum, being the next countdown

The frequency seismogram on the first channel is rewritten from the RAM register 28 to the filter register 29, and the zeros are written to the first cell of the filter RAM 27. The sampling time of the next sample of the frequency seismogram is determined by the counter of the 32 AChK with which the address of the next channel of the frequency seismogram is connected via the selector 31 of the address and the filter RAM 27. The memory capacity of the RAM 27 filter is equal to 48 twenty-bit words.

Since all units of the device are synchronized from one block of logic 3, then the input of the adder 25 from multiplier 11 will always receive information of exactly that channel whose address is set on the address buses of the filter RAM 27 at that time.

The adder 26 can be performed on integrated circuits of type 4-bit full adders K561IM1, selector 31 addresses - on integrated circuits of type 2I-2ILI-NOT series K155ЛР1. To build 27 RAM RAM

pa 537RU9 integrated circuits can be used - static RAM with the organization of 2K bits x 8 bits. ACK 30 and AChC 32 counters are made on integrated circuits TPA K155IE5, K155IED. Registers 28 and 29 of RAM and a filter can be built on integrated circuits such as 4-bit serial-parallel registers K1561IR9,

From the output of the output register 13, the information of the frequency gather on all channels is fed to the input of the RAM 9, where it is stored for the duration of the working session. The capacity of RAM 9 is 32K words. The RAM 9 is controlled by pulses of the same frequency fnK4: a counter of 32 AChK, a filter of 12 low frequencies. The sequence of pulses of the PC “4 Formulate registers a separate frequency divider (not shown).

At the end of the session vibroseis work c. GOS 6 generates a signal of the End of Session (FIG. 3, g), which enters FUI 7 and generates a signal of Length (FIG. 3, g). This signal terminates the Session mode and the Overwrite mode automatically starts, for which, in the IGF circuit 7, all signals necessary for this mode are identical to those of the Session mode signals except for Reg.N. (figure 4, c), which takes on the value of logical zero. , thereby connecting the MP4 unit to work - recording information on a magnetic tape. .

5, in the Overwrite mode, the signal H (FIG. 4, d) is triggered by MP4, {which is a tape drive. At this stage in MP4, the subsequent recording is linked to the end of the last recording in order to fit it correctly. The tape begins to move backward, the previous record marker is read and a reverse command is generated. Then, after 3c, a Start signal is generated from the Start H signal (Fig. 4, d), coming from the IGF 7.

The process of recording on a magnetic tape begins with the formation of an interval greater than or equal to 15.8 mm. After the interval is recorded, the header information, cyclic and longitudinal control codes of the header are recorded and the recording of the interval between

five

0

five

five

title and information. This interval is recorded until the moment mark (NOM) arrives. The time stamp signal is delayed relative to the Start N signal for 500 ms.

With the arrival of the NOM signal (Fig. 4, s), the recording of the information of the frequency gather on the magnetic tape begins. 0 First, this information is read from RAM 9, then goes to logic block 3, In logic block 3, information is divided into bytes and in C1 format goes to MP4. The rewriting of information from RAM to a magnetic recorder takes place in a time shorter than 2 s. .

The operation of all units of the device in both the Session and Overwrite modes is controlled by logic block 3, which performs the following main functions: shaping. flow of information for the purpose of its ordered recording on a magnetic tape and processing of information reproduced from a magnetic tape.

Block 3 logic works as follows,.

The information from RAM 9 enters an intermediate register 33 and is stored therein for the duration of one channel. Further, the information enters the RAM 34 of the record where this information is recorded and stored. The writing and reading from the write RAM 34 is performed using the control circuit of the write RAM 38, which generates the address of the cell in which the information is located. From the write RAM 34, information is supplied to the write register buses of the buffer register 35. The information from the buffer register 35 goes to MP4. The synchronization of the operation of all units of the block is performed by the synchronizer 37, which produces a series of clock pulses. The frequency of the clock pulses varies depending on the speed of the magnetic tape | drive to maintain a constant recording density. The synchronizer 37 generates 16 main GIO-GI15 pulses, which divide the seismic channel sweep time by 16 cycles, while the GMO pulse is used as the switching pulse of the serum channels, the FPS pulse pulses the seismic information into the PSF8 register. Formation of synchronization pulses for

0

five

0

five

transducer unit 2 is produced in a channel counter 39, which also produces a sem pulse, determining the temporary position of the service channels in the frame and separating the seismic information from the auxiliary,

The communication of the logic unit 3 and the IGF7 is carried out by the communication device 41, which receives control signals from the IGF7 and transmits them to the MP4 via the recording logic circuit 40.

Thus, the invention provides the possibility of performing vibroseismic exploration according to a particular method, which allows the use of simple and reliable unbalanced vibrators. The possibility of using such vibrators leads to an increase in the productivity of oil and gas exploration in off-road conditions and low temperatures in Western Siberia. In addition, unbalanced sources make it possible to initiate, along with longitudinal and transverse waves,

Claims (1)

Invention Formula A device for vibroseismic prospecting, containing seismic sensors connected to the first input of the transducer unit, connected by a second input to the first output of the logic unit, the second output of which is connected to a magnetic recorder, in order to expand the field of application of the device, pre five 0 five 0 five a vibroseis signal generator, including a random access memory, connected by an output to the information input of a logic unit, connected in series to a reference signal generator and a driver of control pulses, the pendy output of which is connected to the input of the reference signal generator, the second output connected to the first control input of the operational devices, and the third output is from the control input of the logic unit, and the frequency seismogram generator containing the input register connected in series p, multiplier, the second input of which is connected to the second output of the generator, the reference signal. a, a low frequency filter and an output register, the output of which is connected to the first input of an operational storage device, and the control and information inputs of the input the register is connected respectively to the control and ikformatdionnymi outputs of the transceiver unit; the first and second control inputs of the low-pass filter are connected respectively to the second and third control inputs of the operative memory of the device 1 and vtorP and third outputs of the logic block control yupr th output register input is combined with the third control input of the low pass filter, the fourth control input of the random access memory, and is an external clock input unit. Start Book. F 1 / 2.2 and Lousn with the book. in „Nakoli / Pel , H and: 1G 6 Drive t 6 VM.reg.n e „P1 / scN Oh,. Starti, e „nom fK .Thg. mode, 3 L Fiyo.5 zs ... jl ... jl EriT fjoe / e.ii From 37 FIG. 7 Fie.6 Editor A.Lezhnina CoctaBitel A. Aleshin Tehred M. Khodanych Proofreader L. Tsilipenko Order 6502/44 Circulation 772 VNIIPI USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5 Fiyo.V Subscription