JP7090841B2 - Geophysical exploration method and geophysical exploration equipment - Google Patents

Description

The present invention relates to a geophysical exploration method and a geophysical exploration device, and more particularly to a geophysical exploration method and a geophysical exploration device for exploring topography, resources, etc. by oscillating pseudo-random waves in water or in the ground.

Abundant resources (eg oil, natural gas, methane hydrate, multi-metal baby booms, manganese crusts, submarine hydrothermal deposits, etc.) exist on the continental shelf and deep sea floor, and the ocean is due to the recent rise in resource prices. The need for resource development is increasing. In addition, natural resources on land are unevenly distributed in certain areas, and resources with low domestic production have to rely on imports from foreign countries, and there are many geopolitical risks. In Japan, which is surrounded by the sea on all sides, the marine region is attracting attention as a new frontier for resource development in order to ensure a stable supply of resources.

By the way, a pseudo-random wave (a binary pseudo-random sequence expressed by a wave phase difference) is used in the field of underwater acoustic communication because it has a high correlation between a vibration signal and a vibration received signal. For the same reason, the applicability of pseudo-random waves is being investigated and studied in the field of geophysical exploration (see, for example, Patent Document 1).

In Patent Document 1, a plurality of pseudo-random waves are simultaneously oscillated and received from a plurality of oscillators using pseudo-random code signals having different code arrangements, and analysis is performed to obtain only the signals of the individual oscillators. A non-destructive measurement method by multiple vibrations using a pseudo-random wave characterized by separation is disclosed.

Japanese Unexamined Patent Publication No. 2004-163322

Pseudo-random waves have the property that minute noise is evenly distributed over a wide range when cross-correlation analysis (analysis using a cross-correlation function) is performed. Therefore, when a pseudo-random wave is used in the geophysical field, there is a problem that a minute signal returning from a large depth is hidden by noise.

As a method of solving such a problem, a method of using a sweep wave in which noise generation is limited (larger near the signal but smaller as it goes farther), and a method of lengthening the signal sequence of the pseudo-random wave and S / N A method of improving the ratio can be considered. However, the former method has a problem that noise near the signal at the reflection point becomes large, and the latter method has a problem that the vibration time of the signal becomes long and the use is limited.

The present invention has been devised in view of such a problem, and even when a pseudo-random wave is used, noise can be reduced and geophysical accuracy can be improved, and the present invention can be used for various purposes. , A geophysical exploration method and a geophysical exploration device.

According to the present invention, the exploration data is obtained by oscillating a pseudo-random wave, receiving the reflected wave of the pseudo-random wave, and taking a mutual correlation between the vibration signal of the pseudo-random wave and the vibration signal of the reflected wave. In the physical exploration method to be acquired , any different pseudo-random waves generated by different pseudo-random number sequences are oscillated, exploration data is calculated for each of the plurality of pseudo-random waves, and the plurality of exploration data are used. The integrated exploration data is calculated by adding them together, and the integration is performed by utilizing the fact that the position or time at which the noise of each exploration data obtained based on the different pseudo-random waves appears and the magnitude of the mutual correlation are different. A physical exploration method characterized by reducing the noise of exploration data is provided.

The integrated exploration data may be calculated by a common reflection point polymerization method.

The pseudo-random wave may be intermittently oscillated while moving the oscillating position.

Further, according to the present invention, a sound source capable of oscillating a pseudo-random wave, a plurality of receivers capable of receiving a reflected wave of the pseudo-random wave, an oscillating signal of the pseudo-random wave, and a receiving signal of the reflected wave. A signal processing device that calculates exploration data by taking the mutual correlation of The processing device calculates exploration data for each of the plurality of pseudo-random waves, adds the plurality of exploration data to calculate integrated exploration data, and each exploration data obtained based on the plurality of different pseudo-random waves. Provided is a physical exploration apparatus method characterized in that it is configured to reduce the noise of the integrated exploration data by utilizing the difference in the magnitude of the mutual correlation with the position or time at which the noise appears. Random.

The sound source includes at least one diaphragm, a driving means for driving the diaphragm, and a control device for transmitting a drive signal to the driving means, and the control device comprises the pseudo-random wave by the diaphragm. It may be configured to transmit the drive signal capable of oscillating.

According to the physical exploration method and the physical exploration apparatus according to the present invention described above, since the exploration data is calculated using a plurality of different pseudo-random waves, the appearance position of noise in the exploration data of each pseudo-random wave and the appearance position of noise The sizes are different, and by adding these plurality of exploration data, the noise of each exploration data can be canceled out, and the noise can be reduced.

Therefore, according to the present invention, even when a pseudo-random wave is used, it is possible to reduce noise diffused over a wide range during cross-correlation analysis and improve exploration accuracy. Further, according to the present invention, since it is not necessary to lengthen the vibration time of the pseudo-random wave, it can be used for physical exploration in which the pseudo-random wave is desired to be generated for a short time, and can be used for various purposes. can.

It is a flow chart which shows the geophysical exploration method which concerns on one Embodiment of this invention. It is a figure which shows an example of the acquisition method of the exploration data. It is a figure which shows an example of the 1st exploration data to the 4th exploration data, (a) is the 1st exploration data, (b) is the 2nd exploration data, (c) is the 3rd exploration data, (d) is the 4th. Exploration data, is shown. It is a figure which shows the integrated exploration data which added together the exploration data shown in FIGS. 3A to 3D by the common reflection point polymerization method. It is a figure which shows the comparison between the integrated exploration data shown in FIG. 4 and the exploration data obtained by the conventional sweep wave, (a) shows the integrated exploration data, and (b) shows the exploration data of a sweep wave. .. It is a figure which shows the structure of the sound source used for the geophysical exploration apparatus which concerns on 1st Embodiment of this invention, (a) shows 1st example, (b) shows 2nd example. It is a figure which shows the structure of the sound source used for the geophysical exploration apparatus which concerns on one Embodiment of this invention, (a) shows the 3rd example, (b) shows the 4th example.

Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 7 (b). Here, FIG. 1 is a flow chart showing a geophysical exploration method according to an embodiment of the present invention. FIG. 2 is a diagram showing an example of a method of acquiring exploration data. FIG. 3 is a diagram showing an example of the first exploration data to the fourth exploration data, (a) is the first exploration data, (b) is the second exploration data, (c) is the third exploration data, and (d). ) Indicates the fourth exploration data. FIG. 4 is a diagram showing integrated exploration data obtained by adding the exploration data shown in FIGS. 3A to 3D by the common reflection point polymerization method.

In the physical exploration method according to the embodiment of the present invention, a pseudo-random wave is oscillated, a reflected wave of the pseudo-random wave is received, and a mutual correlation between the quasi-random wave oscillating signal and the reflected wave receiving signal is obtained. It is a physical exploration method that acquires exploration data by means of oscillating multiple different pseudo-random waves, calculating exploration data for each of multiple pseudo-random waves, and adding up multiple exploration data to calculate integrated exploration data. It is characterized by that.

Here, the flow diagram shown in FIG. 1 shows, as an example, a case where four different pseudo-random waves (first pseudo-random wave, second pseudo-random wave, third pseudo-random wave, fourth pseudo-random wave) are oscillated. Is shown. It should be noted that at least two or more different pseudo-random waves may be prepared, and the number is not limited to four.

As shown in FIG. 1, the physical exploration method according to the present embodiment uses the first exploration data acquisition step Step 1 for acquiring the first exploration data using the first pseudo random wave and the second pseudo random wave. The second exploration data acquisition step Step 2 for acquiring the second exploration data, the third exploration data acquisition step Step 3 for acquiring the third exploration data using the third pseudo random wave, and the fourth using the fourth pseudo random wave. It includes a fourth exploration data acquisition step Step 4 for acquiring exploration data, and an integrated exploration data calculation step Step 5 for calculating integrated exploration data by adding the first exploration data to the fourth exploration data.

The first exploration data acquisition step Step 1 includes step 11 for oscillating the first pseudo-random wave, step 12 for receiving the reflected wave of the first pseudo-random wave, and step 13 for acquiring the first exploration data by cross-correlation analysis. , Includes. Similarly, the second exploration data acquisition step Step 2 acquires the second exploration data by cross-correlation analysis with the step 21 for oscillating the second pseudo-random wave and the step Step 22 for receiving the reflected wave of the second pseudo-random wave. Step 23 and is included.

Similarly, in the third exploration data acquisition step Step3, the third exploration data is obtained by cross-correlation analysis with the step Step 31 for oscillating the third pseudo-random wave and the step Step 32 for receiving the reflected wave of the third pseudo-random wave. It includes the step Step 33 to be acquired. Similarly, in the fourth exploration data acquisition step Step 4, the fourth exploration data is obtained by cross-correlation analysis with the step Step 41 for oscillating the fourth pseudo random wave and the step Step 42 for receiving the reflected wave of the fourth pseudo random wave. The step Step 43 to be acquired is included.

Here, the "pseudo-random wave" is a binary pseudo-random sequence (a sequence in which 0 and 1 are randomly arranged) expressed by the phase difference of the wave. For example, if 0 is an upwardly convex signal and 1 is a downwardly convex signal, a random wave is generated by a random number sequence of 0 and 1. At this time, in the pseudo-random wave, a pseudo-random number sequence obtained by a certain calculation is used instead of the true random number sequence. The pseudo-random sequence can be generated, for example, by a pseudo-random sequence generator that includes an algorithm that generates the pseudo-random sequence.

The second pseudo-random wave used in the second exploration data acquisition step Step 2 is a pseudo-random wave generated by a pseudo-random number sequence different from the first pseudo-random wave used in the first exploration data acquisition step Step 1. The third pseudo-random wave used in the third exploration data acquisition step Step 3 is the first pseudo-random wave used in the first exploration data acquisition step Step 1 and the second pseudo-random wave used in the second exploration data acquisition step Step 2. It is a pseudo-random wave generated by a pseudo-random sequence different from.

Further, the fourth pseudo-random wave used in the fourth exploration data acquisition step Step 4 is the first pseudo-random wave used in the first exploration data acquisition step Step 1 and the second pseudo-random wave used in the second exploration data acquisition step Step 2. And a pseudo-random wave generated by a pseudo-random number sequence different from the third pseudo-random wave used in the third exploration data acquisition step Step3.

Here, FIG. 2 shows a sound source 1 capable of generating a pseudo-random wave S, a plurality of receivers 2 capable of receiving a reflected wave R of the pseudo-random wave S, and a signal recovery for collecting the signal received by the receiver 2. An example of a method of acquiring exploration data using the apparatus 3 and the physical exploration apparatus including the apparatus 3 is shown. Further, the geophysical exploration device shown in the figure oscillates a pseudo-random wave from the sound source 1 while submerging the sound source 1 and the vibration receiver 2 in water and towing, and the receiver 2 receives the signal of the reflected wave. The sound source 1 may be a self-propelled type instead of a towed type.

The sound source 1 may include a pseudo-random number sequence generator, or may include a storage device that stores the vibration signal of the pseudo-random wave S generated in advance by the pseudo-random number sequence generator. The configuration of the sound source 1 will be described later. The vibration receivers 2 are arranged in series on the cable 4, for example, at regular intervals. Such a cable 4 is generally called a streamer cable.

The signal recovery device 3 may include a signal processing device that calculates exploration data by taking a cross-correlation between the vibration signal of the pseudo random wave S and the vibration receiving signal of the reflected wave R. Further, the signal processing device may be arranged on the mother ship towing the sound source 1. In this case, the received signal of the reflected wave R is transmitted from the signal recovery device 3 to the signal processing device of the mother ship by wireless data communication or the like.

In such a geophysical exploration device, as shown in the upper part of FIG. 2, while moving the sound source 1 and the vibration receiver 2, the pseudo-random wave S is intermittently oscillated at a predetermined timing, and the reflected wave R is received by a plurality of vibrations. Receive vibration with vessel 2. The sound source 1 and the vibration receiver 2 are moved from the exploration start position to the exploration end position, and one exploration process (scan) is completed. In this one-time exploration process, the exploration is carried out using the same pseudo-random wave S. That is, in the geophysical exploration method shown in FIG. 1, it means that the exploration process (scan) is performed four times.

The vibration-receiving signal obtained by one exploration process (scan) is processed by, for example, a common reflection point polymerization method (CMP polymerization method: Common Mid-Point polymerization method) as shown in the lower part of FIG. In the common reflection point polymerization method, a record having a common reflection point Pcm (a record in which the midpoint of the source point and the vibration receiving point match) is extracted from the vibration receiving data to create a set, and the source point and the receiving vibration are received at the common reflection point. After correcting to a record that has points (NMO correction: Normal Move Out correction), the vibration receiving data included in the set is added to create one polymerization record, and the polymerization records of all common reflection points Pcm are arranged side by side. How to display.

In this way, by processing the received vibration signal using the common reflection point polymerization method, the signal at the reflected wave point is emphasized and noise can be reduced. The method for processing the vibration receiving signal is not limited to the common reflection point polymerization method.

Further, "cross-correlation analysis" is to evaluate the similarity between two time-series signals, and is one of the methods for examining the relationship between the signals. A cross-correlation function is used as an evaluation index of similarity. In the physical exploration method according to the present embodiment, as two signals, the vibration signal x (t) of the pseudo-random wave generated and the vibration receiving signal y (t) of the reflected wave after being processed by the common reflection point polymerization method. And are used. Then, the cross-correlation function Ryx (τ) with respect to the vibration signal x (t) of the vibration receiving signal y (t) is expressed as Equation 1 using, for example, the time difference τ.

In number 1, t means time and x ^* (t) means the complex conjugate of x (t). When the correlation between the vibration signal x (t) and the vibration receiving signal y (t) is low, the cross-correlation function approaches 0 regardless of the magnitude of the time difference τ, and the vibration signal x (t) and the vibration receiving signal y ( When the correlation of t) is high, the cross-correlation function takes a large value at a position of a certain time difference τ. Therefore, when the cross-correlation analysis of the pseudo-random wave is performed, the minute noise is uniformly distributed over a wide range.

By performing the above-mentioned series of processes, exploration data is acquired from the pseudo-random wave. Here, the exploration data shown in FIG. 3A is the first exploration data obtained by the first pseudo-random wave, and the exploration data shown in FIG. 3B is obtained by the second pseudo-random wave. The second exploration data, the exploration data shown in FIG. 3 (c) is the third exploration data obtained by the third pseudo random wave, and the exploration data shown in FIG. 3 (d) is the fourth pseudo random wave. It is the fourth exploration data obtained by.

As shown in FIGS. 3 (a) to 3 (d), the first exploration data, the second exploration data, and the second exploration data obtained by different pseudo random waves (first pseudo random wave to fourth pseudo random wave). The waveforms (cross-correlation and phase) of the third exploration data and the fourth exploration data are all displayed as different. In each figure, the horizontal axis shows the time difference τ (sec), and the vertical axis shows the cross-correlation (dimensionless number). In addition, the exploration data (the peak value of the cross-correlation) that has a high correlation with the vibration signal among the vibration-receiving signals is a value that is remarkably prominent with respect to the portion with a low correlation (the value whose cross-correlation is close to 0). The cross-correlation above a certain value is omitted in the figure.

In the physical exploration method according to the present embodiment, exploration data (first exploration data to fourth exploration data) obtained based on a plurality of different pseudo-random waves (first pseudo-random wave to fourth pseudo-random wave) are used. As shown in FIGS. 3 (a) to 3 (d), it was created by paying attention to the difference between the position (time) at which noise appears and the magnitude of the cross-correlation. That is, the geophysical exploration method according to the present embodiment is characterized in that integrated exploration data with reduced noise is calculated by adding a plurality of different exploration data obtained by a plurality of different pseudo-random waves.

Specifically, in the integrated exploration data calculation step Step 5, after calculating the first exploration data, the second exploration data, the third exploration data, and the fourth exploration data, for example, these explorations are performed using the common reflection point polymerization method. Integrated exploration data is calculated by adding the data. The method of adding integrated exploration data is not limited to the common reflection point polymerization method. For example, the integrated exploration data may be calculated by calculating the average value of the first exploration data, the second exploration data, the third exploration data, and the fourth exploration data. Further, when the sound source 1 and the vibration receiver 2 are fixed, the exploration data from the same reflection point may be polymerized to calculate the integrated exploration data.

FIG. 4 shows integrated exploration data obtained by adding the first exploration data to the fourth exploration data shown in FIGS. 3 (a) to 3 (d) by the common reflection point polymerization method. In FIG. 4, the horizontal axis shows the time difference τ (sec), and the vertical axis shows the cross-correlation (dimensionless number). Further, as in FIGS. 3 (a) to 3 (d), the cross-correlation of a certain value or more is omitted. The integrated exploration data shown in FIG. 4 is displayed at the same scale as the first exploration data to the fourth exploration data shown in FIGS. 3 (a) to 3 (d).

Comparing the waveforms of the integrated exploration data shown in FIG. 4 with the first exploration data to the fourth exploration data shown in FIGS. 3 (a) to 3 (d), a reflection point showing a peak value of cross-correlation. It is obvious that the cross-correlation of the vibration-receiving signal (noise) in the time zone other than the vibration-receiving signal Rp is generally smaller in the integrated exploration data than in the first exploration data to the fourth exploration data.

Here, FIG. 5 is a diagram showing a comparison between the integrated exploration data shown in FIG. 4 and the exploration data obtained by the conventional sweep wave, where (a) is the integrated exploration data and (b) is the sweep wave. Exploration data, is shown. In each figure, the horizontal axis shows the time difference τ (sec), and the vertical axis shows the cross-correlation (dimensionless number). Further, in each figure, the entire vibration receiving signals Rp and Rp'at the reflection point showing the peak value of the cross-correlation are shown without omitting the cross-correlation of a certain value or more.

Conventional sweep wave exploration data has the property that noise generation is large near the signal at the reflection point and decreases as it goes farther. In fact, as shown in FIG. 5 (b), almost no noise appears at a position far from the vibration receiving signal Rp'at the reflection point, but it is surrounded by a position close to the vibration receiving signal Rp'at the reflection point (for example, surrounded by a dotted line). In the region N'), noise appears in a large wavy manner. In this way, when a large noise appears, a minute signal returning from a large depth is buried in the noise and hidden.

On the other hand, as shown in FIG. 5A, the geophysical exploration data obtained by the geophysical exploration method according to the present embodiment has substantially uniform noise with small cross-correlation in the time zone other than the vibration receiving signal Rp of the reflection point. It's just appearing. In particular, when the exploration data contained in the region N of FIG. 5 (a) and the exploration data contained in the region N'of FIG. 5 (b) are compared, they are more integrated than the exploration data obtained by the conventional sweep wave. It can be easily understood that the noise of the exploration data is significantly reduced.

According to the physical exploration method according to the present embodiment described above, exploration data (for example, first exploration data to fourth) are used using a plurality of different pseudo random waves (for example, first pseudo random wave to fourth pseudo random wave). Since the exploration data) is calculated, the noise appearance position and magnitude in the exploration data of each pseudo-random wave are different, and the noise of each exploration data is offset by adding these multiple exploration data. It is possible to reduce noise.

Therefore, according to the geophysical exploration method according to the present embodiment, even when a pseudo-random wave is used, it is possible to reduce noise diffused over a wide range during cross-correlation analysis and improve exploration accuracy. Further, according to the geophysical exploration method according to the present embodiment, since it is not necessary to lengthen the seismic time of the pseudo-random wave, it can be used for geophysical exploration in which the pseudo-random wave is desired to be vibrated for a short time. Can be used for applications.

Here, FIG. 6 is a diagram showing a configuration of a sound source used in the geophysical exploration apparatus according to the embodiment of the present invention, (a) is a first example, and (b) is a second example. .. 7A and 7B are views showing the configuration of a sound source used in the geophysical exploration apparatus according to the embodiment of the present invention, in which FIG. 7A shows a third example and FIG. 7B shows a fourth example. The sound source 1 shown in each figure is merely an example, and the sound source 1 used in the geophysical exploration apparatus according to the present embodiment is not limited to the illustrated configuration.

The sound source 1 of the first example shown in FIG. 6A includes two diaphragms 11, a drive means 12 for driving each diaphragm 11, and a control device 13 for transmitting a drive signal to each drive means 12. , And the control device 13 is configured to transmit a drive signal capable of generating a pseudo-random wave by the diaphragm 11.

The diaphragm 11 has, for example, a disk shape, and is connected to the surface of the casing 14 accommodating the driving means 12 and the control device 13 via an elastic body 15. The two diaphragms 11 are arranged on opposite surfaces of the casing 14. Since the elastic body 15 is arranged on the outer periphery of the diaphragm 11, the diaphragm 11 is configured to be able to reciprocate in a direction perpendicular to the arrangement surface.

The drive means 12 is, for example, a hydraulic cylinder provided with a reciprocating piston rod 12a, and is configured to be operable by operating the servo valve 12b. The tip of the piston rod 12a is connected to the back surface of the diaphragm 11. Therefore, the piston rod 12a and the diaphragm 11 can be reciprocated by adjusting the flow rate of the working fluid supplied to the hydraulic cylinder by the servo valve 12b.

The control device 13 is a computer that transmits a drive signal for driving the piston rod 12a to the servo valve 12b. The control device 13 may include, for example, a pseudo-random number sequence generator in order to generate a pseudo-random wave from the diaphragm 11. Further, the control device 13 may include a storage device that stores the vibration signal of the pseudo-random wave generated by the pseudo-random number sequence generator in advance.

The sound source 1 of the second example shown in FIG. 6B includes a single diaphragm 11, a driving means 12 for driving the diaphragm 11, and a control device 13 for transmitting a driving signal to the driving means 12. The control device 13 is configured to transmit a drive signal capable of generating a pseudo-random wave by the diaphragm 11. The sound source 1 of the first example includes two drive units including the diaphragm 11 and the drive means 12, whereas the sound source 1 of the second example includes one drive unit. Since each configuration of the sound source 1 of the second example is the same as that of the sound source 1 of the first example described above, detailed description thereof will be omitted.

For example, as shown in FIG. 2, the geophysical exploration device including the sound source 1 of the first example is suitable for an exploration method in which a pseudo-random wave is intermittently oscillated in water while moving the oscillating position. The geophysical exploration device according to the present embodiment is not limited to the use for the geophysical exploration method shown in FIG.

For example, the physical exploration device according to the present embodiment may intermittently generate a pseudo-random wave on land while moving the vibration position, or the sound source 1 and a vibration receiver on the ground, underwater, or seabed on land. Pseudo-random waves may be emitted intermittently with 2 fixed. When a pseudo-random wave is emitted toward the ground or the seabed, for example, the sound source 1 of the second example shown in FIG. 6B can be used.

The sound source 1 of the third example shown in FIG. 7A is a modification of the configuration of the driving means 12 in the sound source 1 of the first example. The drive means 12 includes, for example, a reciprocating drive rod 12c and an electric coil 12d that drives the drive rod 12c by an electromagnetic force. Even with this configuration, by passing a current through the electric coil 12d, an electromagnetic force in the direction of the arrow in the figure can be generated to reciprocate the drive rod 12c.

When changing the driving direction of the driving rod 12c, the direction of the current flowing through the electric coil 12d may be reversed. Further, conditions such as the direction, magnitude, and time of the current flowing through the electric coil 12d are controlled by the control device 13.

The sound source 1 of the fourth example shown in FIG. 7B is a modification of the configuration of the driving means 12 in the sound source 1 of the second example. Since the configuration of the driving means 12 is the same as that of the sound source 1 of the third example described above, detailed description thereof will be omitted.

In the above-described embodiment, a case of generating a plurality of different pseudo-random sequences is described as a method of oscillating a plurality of different pseudo-random waves, but the method of oscillating a plurality of different pseudo-random waves is limited to such a method. It is not something that will be done. For example, even when the same pseudo-random sequence is used, a plurality of different pseudo-random waves can be oscillated by oscillating at a plurality of different frequencies.

For example, the frequency of the first pseudo-random wave may be set to 200 Hz, the frequency of the second pseudo-random wave may be set to 195 Hz, the frequency of the third pseudo-random wave may be set to 205 Hz, the frequency of the fourth pseudo-random wave may be set to 190 Hz, and the like. .. In this way, by using the same pseudo-random sequence and different focal frequencies, the noise appearance positions can be different.

The present invention is not limited to the above-described embodiment, and can be used for various purposes such as not only research on marine resources but also research on mining resources, civil engineering / environmental research, and the like. Of course, various changes can be made without deviation.

1 Sound source 2 Sound receiver 3 Signal recovery device 4 Cable 11 Vibration plate 12 Drive means 12a Piston rod 12b Servo valve 12c Drive rod 12d Electric coil 13 Control device 14 Casing 15 Elastic body Step1 First exploration data acquisition step Step2 Second exploration data acquisition Step3 Third exploration data acquisition step Step4 Fourth exploration data acquisition step Step5 Integrated exploration data calculation step

Claims (5)

It is a physical exploration method that acquires exploration data by oscillating a pseudo-random wave, receiving the reflected wave of the pseudo-random wave, and taking mutual correlation between the vibration signal of the pseudo-random wave and the vibration signal of the reflected wave. There,
Arbitrarily different multiple pseudo-random waves generated by different pseudo-random number sequences are oscillated, exploration data is calculated for each of the plurality of pseudo-random waves, and the plurality of exploration data are added together to calculate integrated exploration data. ,
The noise of the integrated exploration data was reduced by utilizing the difference in the magnitude of the cross-correlation with the position or time at which the noise of each exploration data obtained based on the different plurality of pseudo-random waves appears. ,
A geophysical exploration method characterized by this. The geophysical exploration method according to claim 1, wherein the geophysical exploration data is calculated by a common reflection point polymerization method. The geophysical exploration method according to claim 1, wherein the pseudo-random wave is intermittently oscillated while moving the oscillating position. Exploration by taking a cross-correlation between a sound source capable of generating a pseudo-random wave, a plurality of receivers capable of receiving the reflected wave of the pseudo-random wave, and a vibration signal of the pseudo-random wave and a vibration signal of the reflected wave. Equipped with a signal processing device that calculates data
The sound source is configured to be capable of emitting any number of different pseudo-random waves generated by different pseudo-random sequences .
The signal processing device calculates exploration data for each of the plurality of pseudo-random waves, adds the plurality of exploration data to calculate integrated exploration data, and obtains each of the plurality of different pseudo-random waves. It is configured to reduce the noise of the integrated exploration data by utilizing the difference in the magnitude of the cross-correlation with the position or time at which the noise of the exploration data appears .
A geophysical exploration device characterized by this. The sound source includes at least one diaphragm, a driving means for driving the diaphragm, and a control device for transmitting a drive signal to the driving means, and the control device comprises the pseudo-random wave by the diaphragm. The physical exploration device according to claim 4, which is configured to transmit the drive signal capable of vibrating.

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