Seismic recording method using separate recording units for each group

The invention relates to a seismic Aufschlußverfahren and an arrangement for carrying out the digestion process on land.

Arrangements are known for carrying out seismic digestion methods which contain a plurality of seismic probes or sensor groups, the outputs of which are connected to a central data recorder via a multi-pair conductor containing land seismic cable. These arrangements have become known as central arrangements because of the central data recorder.

In particular, the central assembly includes a source of seismic energy and a plurality of seismic probes for attachment to known locations in a digestion area. The seismic probes are connected to electrical conductors contained in a seismic land cable. The output signals appearing on the electrical conductors of the land cable are applied to an analogue section whose external signals are applied to a digital section. The analog section contains for each probe frequency filters for obtaining the desired frequencies and an amplifier with a programmed or automatic gain control for keeping constant the desired output signal independently

of fluctuations in the input signal strength. Furthermore, a camera or a cathode ray tube is provided for the visual display of the desired detected signals for the purpose of quality monitoring as well as a digital section. The digital portion includes a multiplexer which samples each probe output in accordance with a timing signal. The sampled probe signals from the multiplexer are converted from analog signal type to digital signal type by analog-to-digital converters and sent through a read / write amplifier for recording on a digital tape »

The central arrangement is applied as follows <i>% </i>The Land Surveying Squad is provided with a map of a designated prospecting area, which is often referred to as a prospecting area. * The survey crew uses this map to locate and mark the antenna or sensor group locations, del? Source locations or source routing and a controller location. The survey crew is then followed by a field crew_? the up to 60 sensors or sensor groups at the marked sensor positions, a source of seismic energy at the source positions and a control unit »the control unit comprises the data processing and data recording equipment, which can be spatially separated from the control unit«, Then a⁴ Main country cable between the probes or sensor groups and the control unit designed, and the sensors or sensor groups and the recording devices of the control unit <i>'цп </i>the land cable connected. The control unit executes a corresponding shot point mark on the recording tape and actuates the sources one or more times to generate the seismic energy for a seismogram. The sensors then directly detect the seismic energy, as well as any reflected and diffracted energy. · The energy is transferred from the multi-paired seismic land cable to the recorders »The output of each probe or group of probes is from

sampled, digitized and recorded on the magnetic tape of a tape device that can handle up to 60 input channels. The seismic arrangement is then moved on to the next location, and the process is repeated. "

The disadvantage of the known central arrangements lies in the use of a seismic land cable and in the processing of the multiplexed data recorded on the magnetic tape. The seismic land cable is a piece of equipment that causes high costs in manufacturing, maintenance and field use. A large length and a large volume require special pick-up and transport facilities and additional work for laying out and picking. Each multiplexing system has an upper limit on the number of probes or probe groups that can be used. In addition, the multiplexed raw data for processing the final product, the seismogram, must be demultiplexed.

The object of the invention is to provide an effective and economical seismic disintegration method for use in the countryside and an arrangement for carrying out this method, which

- manages without a seismic land cable in the data acquisition system,

- Contains a recording system that is directly compatible with the central data processing unit, and collected in the raw data in a demultiplexed form, the data collection system for each sensor group used contains an independent data acquisition unit, and finally

- Creates a distributed seismic data recording system, in which a minimum number of bits per recording is used, the number of analog operations with the data is reduced and the number of digital functions using integrated circuits is increased to a maximum.

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This object is achieved in terms of the method according to the invention that ''

in a section of the digestion area, a plurality of data acquisition units, each of which contains a control part for its operation control, a seismic sensor known per se for detecting seismic energy and its conversion to an electrical representation, and a recording device connected to the sensor for recording the electrical diagrams .

the control parts of the data acquisition units are placed in a standby mode,

in order to detect seismic energy and to generate and record an electrical representation of this seismic energy, a selective signal transmission from the main control arrangement takes place for switching the data acquisition units from the standby operating state into the active operating state,

the main control arrangement selectively sends out signals which move the data acquisition units from the active operating state to the inactive operating state and additional data acquisition units from the operating mode

• switch the standby mode to the active operating state, and

- the data acquisition units in inactive condition are retrieved in order to replace the recording devices therein for the further use of the data collection units in the digestion area, and the records of the processing

Processing of the seismic data in the main control arrangement and in a data recording unit to a desired format are reproduced.

The arrangement according to the invention is characterized by a plurality of data acquisition units in a housing, the sensors for detecting a reflected seismic energy and recording devices for recording the of the

elastic body emanating outgoing seismic energy and information and control means for their selective control, wherein the recording devices are connected to the seismic probes and a removable record carrier for recording the electrical outputs of the seismic probes included. In this case, the recording devices can work both with a tape slot and with tape cartridges. According to the invention, a device for processing the detected data is provided, which, in order to carry out an at least partial processing of the electrical output signals of the seismic sensor, is connected thereto. In this case, the data acquisition units are arranged individually at spaced-apart predetermined locations with respect to the elastic body. Another influencing variable is the on-land digestion area, after which the data acquisition units are arranged in predetermined patterns at predetermined locations. ', ·

Connected to the output of the seismic probe is an analog-to-digital conversion arrangement for converting the electrical signals corresponding to the seismic energy from an analog form to a digital form. This analog-to-digital conversion arrangement includes a plurality of series circuits of limited amplifiers and quantization circuits, which are used to form a series parallel with the sensor.

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circuit are connected in parallel with each other. Furthermore, the analog-to-digital conversion arrangement includes a plurality of series-connected limited amplifiers connected in series with the sensor and a plurality of quantizing circuits, each connected to an output of a respective limited amplifier. Finally, a data processing device is provided which processes the digitized data signals.

The invention will be explained in more detail using an exemplary embodiment. According to the accompanying drawing shows:

1 is an illustration of the portable distributed seismic land disassembly arrangement according to one embodiment of the invention;

embodiment of the invention,

FIG. <i>Zi </i>a block diagram of a usable in the inventive arrangement data acquisition unit,

3i is a block diagram of the main control unit for the data acquisition units, the source of seismic energy, and the collection unit;

4 is a block diagram of a full-range fixed gain analog-to-digital conversion array with multiple digital output signals in fixed point representation;

Fig. 5 is a block diagram of another embodiment of the full-range fixed gain analog-to-digital conversion arrangement with multiple digital output signals in fixed-point representation and

6 is a block diagram of a microprocessor for

Digital signals in the data acquisition unit

contained and outputs a single digital output signal in floating-point representation «

Referring to Fig. 1, the portable distributed seismic disintegration assembly for use on land to be described is shown. This arrangement includes a first vehicle 10 which moves with a crew through a surveyed prospecting area. The crew attaches data acquisition units 12 with probes or probe groups 14 for marked-out, two- or three-dimensional data acquisition. The sensor groups may consist of one or more geophones 14, which may be either motion-sensitive or pressure-sensitive. The Geo Space (Hall Sears) HS-J Subminiature Land Detector is a geophone suitable for use in a sensor array. Two or more geophones 14 are arranged sequentially and may be interconnected in either a series arrangement or in a series-parallel arrangement. While there is shown a four-armed star configuration with two geophones 14 per arm (Figure 1) emanating from a centrally mounted transceiver 16, it is also possible to use a nine-arm star with six elements per arm as well how to achieve excellent results with a discrete surface area of ​​a 4x4 square. After the data acquisition unit 12 is properly mounted here, it is turned on and placed in a standby state. The identifier and the location of each data acquisition unit are communicated to a main control and ordering unit 24, which will be described below. While there is shown a four-armed star configuration with two geophones 14 per arm (Figure 1) emanating from a centrally mounted transceiver 16, it is also possible to use a nine-arm star with six elements per arm as well how to achieve excellent results with a discrete surface area of ​​a 4x4 square. After the data acquisition unit 12 is properly mounted here, it is turned on and placed in a standby state. The identifier and the location of each data acquisition unit are communicated to a main control and ordering unit 24, which will be described below. While there is shown a four-armed star configuration with two geophones 14 per arm (Figure 1) emanating from a centrally mounted transceiver 16, it is also possible to use a nine-arm star with six elements per arm as well how to achieve excellent results with a discrete surface area of ​​a 4x4 square. After the data acquisition unit 12 is properly mounted here, it is turned on and placed in a standby state. The identifier and the location of each data acquisition unit are communicated to a main control and ordering unit 24, which will be described below. however, even with a nine-armed star with six elements per arm, as well as a discrete surface field of a 4x4 square, excellent results can be achieved. After the data acquisition unit 12 is properly mounted here, it is turned on and placed in a standby state. The identifier and the location of each data acquisition unit are communicated to a main control and ordering unit 24, which will be described below. however, even with a nine-armed star with six elements per arm, as well as a discrete surface field of a 4x4 square, excellent results can be achieved. After the data acquisition unit 12 is properly mounted here, it is turned on and placed in a standby state. The identifier and the location of each data acquisition unit are communicated to a main control and ordering unit 24, which will be described below.

The vehicle 10 with the crew mounting the data acquisition unit is followed by a second vehicle 18 which carries a crew for mounting a seismic source 20 at marked locations along the source route defined by the survey crew. <i>If </i>the seismic source 20 is properly mounted, the main control unit 24 accommodated in the truck 22 is informed, which thereupon coded signals

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to the data acquisition units 12 for indicating the standby state of selected S¹UhIergruppen sends in the active operating state and to activate the seismic source, whereby a Vorsatζinformation is recorded first. Thereafter, the source is put into operation and finally becomes. Raw data is collected and recorded by the data acquisition units 12. The seismic source 20 may be any suitable source, for example, a source containing dynamite or a non-dynamite source, as described in Pig. 1 is shown. When using a dynamite source, less marked source positions are required because of the strength of the seismic energy generated. If a non-dynamite source is used, up to 40 positions between each pair of probe grids may be required. Due to poor ground coupling, up to 100 individual records must be superimposed to achieve a reasonable noise margin. Examples of suitable non-dynamite sources are: A mobile gas chamber into which propane and oxygen are introduced and exploded against a large mass to couple the explosive energy to the broth surface. A compressed air gun, a drop weight machine, and a pulse compression device are further examples. The last-mentioned device has the advantage over other sources operating without dynamite that the frequency component of the singing signal is known and controllable. This is a great help in filtering out unwanted energy. The pulse duration (7 seconds), however, causes the emergence of strong surface waves,

The vehicle 20 carrying the source 20 is followed by a third vehicle 22, in which the main control and positioning unit 24 is located, which contains a transmitting and receiving radio. Furthermore, there is a crew in the vehicle,

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which overtakes the Pühler groups again. As already mentioned, the main control unit is in a second connection with the field crews and with the data acquisition and source units to receive flags of the data acquisition units, send activation signals and header information to the data acquisition units 12, and turn on or fire the source 20. After the data acquisition units 12 (now in active operating state) have collected the raw seismic data for their present location, coded high frequency signals are sent out to switch the active operating state of these seismic groups to an inactive operating state. In this inactive mode, a search signal may be generated by a target finder included in each data acquisition unit 12 to facilitate the collection of the inactive data collection units 12. The collected data collection fetches 12 are (after the crew have replaced the pre-recorded data bins with fresh data bins) for further use in the digestion area with the vehicle 10 used to mount the data acquisition units. The recorded data bins are then entered into the data arrangement arrangement described below for processing. The collected data collection fetches 12 are (after the crew have replaced the pre-recorded data bins with fresh data bins) for further use in the digestion area with the vehicle 10 used to mount the data acquisition units. The recorded data bins are then entered into the data arrangement arrangement described below for processing. The collected data collection fetches 12 are (after the crew have replaced the pre-recorded data bins with fresh data bins) for further use in the digestion area with the vehicle 10 used to mount the data acquisition units. The recorded data bins are then entered into the data arrangement arrangement described below for processing.

According to j_e 2, the illustrated data acquisition unit 12 includes a signal conditioning unit 30 connected to the output of the sensor array 14 for conditioning the seismic signals for digitization by an analog-to-digital converter 32. The signal conditioning unit and the analog-to-digital converter are turned on when the data acquisition unit 12 in FIG the active operating state is set. Since the data acquisition unit 12 is controlled by a main control unit to be described later, a high frequency amplifier 34 is provided for receiving coded signals from the main control unit. For the necessary control, control commands are used which modulate an audio-frequency sound carrier, which in turn modulates an HF carrier (or is transmitted via a direct wire).

Now follows, the description of a typical example of the control command arrangement. Control commands consist of address commands and group commands. Address commands consist of a basic command followed by a series of addresses. All data acquisition units receive and store the basic address command. If, in the row of addresses following the basic command, the position indicator of a data acquisition unit appears, then this data acquisition unit follows the command. Typical address commands are; Enter the active standby state, write flag / status block, enter the inactive standby state, and enter catch-up state. Group commands consist of a basic command that may or may not be followed by a series of numbers. "Group commands are followed by all data collection units. which have been placed in the active state by an address command. The series of numbers following the basic command of a group command is recorded in the header section of an event as a control variable. Typical group commands are; Start Shot Point Count (start of record of this event number), timeout (time at which the source event takes place), and finish shot count (completion, record of this event count).

Here is a typical example of the bit and word structure used in command transfer. The bitmap information is represented by a Barker code that uses a particular code group to represent "fiins," "zero," and "space." The Barker code groups are generated from an original binary sequence of logical "sins" and "zero" bits, preferably 128 bits. The original binary sequence of logical "one" and "zero" bits modulates the auditory frequency carrier, as previously described._лTypical modulation types are Phase Shift Keying (PSK) or Frequency Shift Keying (FSK). On the receiver side, the binary sequence is detected bit by bit and continuously correlated with each Barker code group to allow either "bins",^ч "xTull" or "gap" fixed

If there is a correlation above any threshold, say 50%, then one bit of the control information has been detected. To transfer the information bits for the logical "sins"₉ the logical "zero" and the information "space" are used by three Barker God groups. The control commands are converted from these bit-serialized ^¹Orm Arranged Bit Groups »Two-stage phase modulation is used to transmit the Barker code groups in the sound carrier. This method has been chosen because of the low information content required for the controller and the need for high reliability of the radio link. Of course, other coding and tone modulation methods utilizing any particular binary coded command group may be used where, for example, a sound modulation is generated »^ч

The RF receiver 34 is electrically connected to a decoder 36 which demodulates the audio carrier signals and converts them into bit serial digital signals for the controller 38. The control unit 38 addresses and controls the data acquisition unit 12 in dependence on the decoded signals in such a way that it determines its operating state, ie_O If the control unit 38 receives a signal for switching the data processing unit to an active operating state, then a switch 40, which may consist of a magnetically operated switch, is closed, so that a data recording device 42 , which may be, for example, a data tape cartridge or a cassette tape recorder, connected to a power source 46. The data logger may be, for example, a data cartridge suitable for recording header information, timing signals, and digitized output signals of analog-to-digital converter 32. The data acquisition unit 10 may be provided with a monitor 44 which is connected to the control unit.

unit 38 is connected »so that the operation of Järfassungsseinheit 12 after its attachment in the field., But before activation of the source can be tested. To facilitate ringing of the data acquisition unit 12, the monitor 44 may be equipped with a target locator (not shown), such as a horn or other signaling device, which includes an electromagnetically controlled switch responsive to a signal received from the controller 38 Command to switch from the active to the inactive state becomes effective. The power supply unit can be, for example, a battery unit that contains the other electrical components of the data acquisition unit, such as the receiver 34₉ the signal conditioning unit 30, the analog-to-digital converter 32, the retrieval-indicating device (not shown), and the data recorder 42 - the power supply unit should have the capability to set a standby state for 48 hours and an active period /

for one and a half hours. The inactive period is not critical, and it can, if it exists at all_s be designed that way_s that the requirements of a desired Sinholperiode is taken into account.

The signal conditioning unit 30 (Figures 2 and 4) for the data acquisition unit 12 may be a typical analog signal conditioning unit or arrangement which may be a bounded antialiasing filter 50 (Figure 4) for passing desired frequencies is electrically connected to the output of a group of seismic sensors 14. The desired frequencies are input to a hormonal circuit 52 to multiply the amplitudes of all the seismic signals by a constant value to fall within the range of a fixed gain, full-range analog-to-digital device 32 which provides a plurality of digital output signals in fixed point representation provides "

The array 32 includes a plurality of limited gain stages 54 connected to the output of the kormalization circuit 52 in parallel or as shown in FIG. The output of each amplifier stage is connected to its own Ы-bit quantization circuit 56. The series connection of the limited amplifiers (Fig. 5) forms a cascade amplifier counterpart to the parallel amplifier circuit (Fig. 4). The limited amplifier circuit may be one of the circuits described in section 1.25 of the Philbrick Application Manual on George A. "Philbrick Inc. 1966 Computing Amplifiers." In the distributed arrangement, a full range system is used._e A ratio of one million to one between the largest and smallest occurring signals. The number of binary digits (bits) required for the analog-to-digital converter is determined by assuming that the validity of the stacking is based on the overlay principle. Thus, the data acquisition system must be a linearly fixed-time system, regardless of ambient noise level. "This means that the smallest signal of interest must be estimated and quantized to a degree of precision that can be considered as a linear representation of the signal." in bits required to assume amplitude linearity for each one-way signal is three. Thus, for the 120db range, 23 bits are the minimum number, to linearly adapt the Sleitkommamantisse between the extreme values ​​in decibels of simultaneously arriving signals to be separated by additive processes (stacking)., And to represent the true amplitude plague representation of the seismic data between the extreme values ​​in decibels of signals, the ever happen is needed. A single analog-to-digital converter can not fulfill this requirement

Therefore, either the arrangement of FIG. 4 or the arrangement of Pig 5 are required. The optimum number of amplifier stages 54 constituting the limited amplifiers is determined as follows: Each amplifier stage has its own U-bit quantization circuit 56, so that each stage corresponds in a linear manner to about б (Ж-1) db of the signal range. Each quantization circuit contains a number of redundancy bits (R) with respect to an adjacent quantization circuit 56. Thus, the dynamic range of each amplifier stage overlaps the dynamic range of the adjacent amplifier stage by about 6 (R-1) db. The entire fixed-frequency range shown comprises M bits, where: M = R + K (NR) · The dynamic range is about 6 (MD db, but only about 6 (n-1) db of this range are always linear._S Kf = 12, M = 24). By substituting these values ​​into the formula M = R + K (NR) and solving this equation for K, the number of required steps is given by 4β

In the preferred embodiment of analog signal conditioning and analog-to-digital conversion, no analog switches are needed. Four tracking type converters are used. In the analog-to-digital conversion arrangement with four fixed-point digital output signals, one for each of the four quantization circuits 56, either the data recorder 42 must be able to record four output signals in fixed-point representation, or a conversion from the fixed-point representation to the floating-point representation be provided so that the data are combined into a floating point output signal, ie in a data representation with mantissa and exponent. A single (combined) floating point signal is the preferred data recording format.

The preferred method for combining the four digital fixed point output signals of the quantization circuits 56 is in Pig. 6 shown in this figure form the. digital signals (D to D) together with a discrete signal (L. to L) (used to indicate whether the quantization circuit follows the analog signal within the linear operating range and is not saturated) of the quantization circuits provide inputs to a multiplexer 90 which multiplexes an input signal consisting of 4x (H + 1) bits into an output signal consisting of (N + 1) bits. Multiplexer 90 multiplexes the digitized signals for a microprocessor 92 for processing digital signals recorded on a semiconductor die in FIG large scale is integrated in metal oxide semiconductor technology (LSr (MOS)) and which is programmed so that it performs desired punctures, such as multiplexer control via feedback ladder 94s, processing and averaging the fixed point input signals, converting pest comma signals into floating point signals, balancing, and nonlinear filtering (to compensate for transducer characteristics and unwanted induced signals) antialiasing and a resampling. The output signals of the microprocessor, which may have any desired format, for example, a mantissa (M) and an exponent (E) summarized (M + E) representing the processed floating-point signal, are input to the data recorder 42 (Fig. The data recording device 42 used is preferably a data insert "3M-DC 300 A Data Cartridge". such as the multiplexer control via feedback ladder 94s, conditioning and averaging the fixed point input signals, converting pest comma signals into floating point signals, balancing, and nonlinear filtering (to compensate for transducer characteristics and unwanted induced signals) antialiasing and resampling. The output signals of the microprocessor, which may have any desired format, for example, a mantissa (M) and an exponent (E) summarized (M + E) representing the processed floating-point signal, are input to the data recorder 42 (Fig. The data recording device 42 used is preferably a data insert "3M-DC 300 A Data Cartridge". such as the multiplexer control via feedback ladder 94s, conditioning and averaging the fixed point input signals, converting pest comma signals into floating point signals, balancing, and nonlinear filtering (to compensate for transducer characteristics and unwanted induced signals) antialiasing and resampling. The output signals of the microprocessor, which may have any desired format, for example, a mantissa (M) and an exponent (E) summarized (M + E) representing the processed floating-point signal, are input to the data recorder 42 (Fig. The data recording device 42 used is preferably a data insert "3M-DC 300 A Data Cartridge".

The main control and positioning arrangement 24 for sustained-operation operation may be a hand-programmed arrangement including (as shown in FIG. 3) one or more transmit and receive radios 60, which may be any RF transmit transceiver, For example, the device "RCA Personal" is 15О ". The radio 60 is connected to a speech transmission unit 62 for voice communications with the field crews who are the data-gathering agents.

lay units 12 and attach the seismic source 20 along the source cup and operate. The punk device 60 is also connected to a hand control 64 shown in phantom in FIG. 3, which is manually programmed to send encoded signals to the data acquisition units 12 and to the source 20. The encoded signals include an on and off signal a data acquisition unit identifier for activating selected data acquisition units 12, a signal for controlling tape movement in data tape insertion, a zero-time signal for correlating the activation of the source, and forming a time base for the data acquisition units, a pass number code for identifying each source event on the tape if a source of vibration is used, and a timing signal near the end of recording in the data acquisition units 12. After recording the data for the shot point, the active data acquisition units 12 (Fig. 1) are switched to the inactive state until all data acquisition units have been used. Then they are collected and used again at other shot points.

In order to control the quality of the data, the main control assembly 24 may be made part of a field-use correlation and registration system; Furthermore, it can be heavily automated. In order to achieve this, the manual control 64 shown in dashed lines in FIG. 3 is replaced by a transmission control unit 66. The transmission control unit 66 operates in accordance with a program of a small computer 68 in such a way that the coded signals for the operation of the data

and the seismic source 20 are supplied, and that the tape of the Datenbandeinschubs the necessary intent information are supplied to the minicomputer 68 is an installable in the field calculator, eg computer "Texas Instruments 980 A". The small computer 68 is

a disk storage 70 which is addressable via an ISin / Aѳѳabe control unit 72; furthermore, the small

computer 68 with a quality control monitor 74 equipped with a quality control input / output controller 76. The input to the minicomputer 68 is via at least one data tape rack controller 76a of at least one high speed tape recorder with data tape slot (this apparatus operates at least 24 times faster than the scan time recording speed). The output from the minicomputer 68 is via a scheduler tape recorder I / O controller 80 to a scheduler tape device 82.

The playback speed must be a factor faster than the recording speed, the factor being equal to the number of active data acquisition units 12 operating simultaneously. This number can range from 24 to 60 or more. Thus, more than one high speed playback tape device 78 may be required so that the binarization process does not lag behind the off-the-shelf operations. The tape player may be any device that meets the above-mentioned requirements. The already mentioned device "3M DC300A Data Cartridge" can handle a ratio of 180 to 1.

The block size of this Dateneinsehubs matches the workspace in the minicomputer. In the demultiplexed form, the recorded data is well suited for stacking and correlation operations. The data tape slot can be recorded up to 2500 times without degradation of recording power at a packing density of 63.0 bits per centimeter (1200 bits per inch).

The minicomputer 68 may be packaged to combine multiple operations to reduce the time and cost of processing raw data into typical seismic information. Thus, when using multiple slices in one for quality monitoring and data

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the output is stacked and reassembled appropriately after a quality check of the data, the minicomputer effects the recording of the header information in the desired format, as well as the recording of the classified data.