Sweeping for marine vibrators with reduced degradation and/or high maximum allowable signal distortion

FIELD: physics; geophysics.

SUBSTANCE: invention relates to geophysics and can be used in seismic exploration to detect oil and gas deposits. The invention discloses a method and an apparatus for marine seismic survey using one or more movable marine seismic vibrators. The sweeping function for the vibrator is based on the criterion of allowable degradation and is a nonlinear function which performs frequency sweeping from top downwards. The obtained data can be used directly without cleaning or can be easily cleaned.

EFFECT: high accuracy of survey data.

21 cl, 11 dwg

 

The LEVEL of TECHNOLOGY

[0001] the Present invention relates to the field of seismic exploration for the discovery of oil and gas fields and, in particular, but not exclusively, relates to marine seismic exploration using a marine vibrator with a reduced amount of blur or increased the maximum allowable distortion of the signal.

[0002] Seismic exploration includes exploration of underground geological formations for the detection of hydrocarbon deposits. Exploration may include the placement of the seismic source (s) and seismic sensors at predetermined locations. These sources generate seismic waves, which propagate into the geological formations, creating along the way the pressure changes and vibration. Changes to the elastic properties of the geological formation scatter these seismic waves, changing their direction of propagation and other properties. Part of the energy emitted by the source reaches seismic sensors. Some seismic sensors are sensitive to pressure changes (hydrophones), others are sensitive to particle motion (geophones); for exploration on an industrial scale it is possible to apply one type sensors or sensors of both types. In response to the detected seismic events, the sensors generate electrical signals to create seismites�th information. Subsequent analysis of this seismic data can show the presence or absence of probable locations of hydrocarbon deposits.

[0003] Some types of intelligence known as "marine exploration, since they are carried out in the marine environment. However, "sea" exploration can be done not only in environments with salt water, but in fresh or in salt water. In one type of naval intelligence, called "scouting for towed seismic installation, a survey vessel tows a system of seismic cables containing seismic sensors and sources. In one type of naval intelligence, called "the definition of marine vertical seismic profile (marine VSP), the set of sensors is placed in the borehole, a seismic source or moved (e.g., towed behind the vessel), or you'll be fixedly (e.g., suspended to this design as the drilling rig). In one type of naval intelligence, which are used as hydrophones and geophones, called "bottom-KOs (DK)", sensors placed on the bottom of the sea. In marine exploration of another type sensors are placed other ways, and the seismic source is installed in the water a certain way, where the sensors or sources can be mobile or fixed. Other types of intelligence are called "terrestrial" types of intelligence, POSCO�ECU they are in the terrestrial environment. During the ground reconnaissance as sources can be used dynamite or seismic vibrators. On the ground laid a system of cables containing seismic sensors for receiving seismic signals. These seismic signals can be converted, to lead in digital form, record or transfer from the sensors to the media and/or processing means, located nearby, for example, to a mobile geophysical laboratory. During the ground reconnaissance can also be used wireless receivers, allowing to avoid the limitations of cables. Seismic surveys can also be carried out in the zones between land and sea, called "gray areas."

[0004] Theoretically, when carrying out marine seismic sources can be pulsed sources (e.g., airgun) or continuous (for example, marine seismic vibrators). However, in practice, marine seismic vibrators usually do not apply. There is a need to make a marine seismic vibrators another applicable type of source for marine seismic exploration.

Summary of the INVENTION

[0005] This description of the invention is intended for representation of concepts are described in more detail below in the detailed description�AI of the invention. This description of the invention is not intended to identify key or the most important features of the subject of discussion and is not intended to limit the scope of the claimed subject matter.

[0006] This disclosure describes methods and apparatus for marine seismic exploration, where the source is applied to marine seismic vibrator. These methods include the use of sweep functions that reduce the need to clean up the blur dipole data sources or increase the maximum allowable distortion, resulting blur, harmonics, etc., These methods may also include the use of sweep for the vibrator, which can provide adequate low-frequency energy for seismic imaging. The instrument includes the marine seismic vibrators that can be used in marine seismic surveys, and the data are easily cleaned from blurring or may not require treatment.

[0007] In variants of the embodiment of the present invention, a marine seismic vibrators used to generate the seismic data, either already generated purified, or can be easily cleaned, and processed to determine properties of a subterranean Land.

BRIEF description of the DRAWINGS

[0008] Option� embodiment of the present invention described with reference to figures given below. In all figures to designate identical features and components use the same item numbers. The methods and apparatus of the present invention can be better understood by considering given below detailed description of some embodiments of the invention in conjunction with the accompanying drawings, where:

[0009] figure 1 shows seysmoregistriruyushchiye system in the marine environment;

[0010] figure 2 shows the energy Em(f) single-frequency output signal of the marine vibrator;

[0011] figure 3 shows an example of the relationship of signal-to-noise ratio (SNR) on two-dimensional seismic image using different sources;

[0012] figure 4 shows several features sweep;

[0013] figure 5 presents several functions sweep and SNR;

[0014] figure 6 presents a schematic representation of a computer system that can be used to implement some of the methods described herein;

[0015] figure 7 shows a block diagram of a method in accordance with one embodiments of the invention;

[0016] figure 8 shows the curves of constant phase error in the frequency band or range of wavelengths;

[0017] figure 9 shows the error of the multiple functions of the sweep;

[0018] figure 10 shows the error of the multiple functions �of viperone with distortions; and

[0019] figure 11 shows a block diagram of a method according to one of embodiments of the invention.

DETAILED description of the INVENTION

[0020] Hereinafter will be described variants of embodiment of the invention, examples of which are provided on the accompanying drawings and figures. This detailed description, numerous specific details are shown in order to provide complete understanding of the invention. However, the usual specialist qualification in this field will be understood that the present invention can be implemented in practice without these specific details. In other instances, well known methods, procedures and systems are not described in detail so as not to complicate the consideration of some aspects of the invention.

[0021] it Should also be understood that although the description of the various elements used terms such as "first", "second", etc., however, these terms are not limiting with respect to these elements. These terms are only used to distinguish one element from another. For example, the first object or the stage can be called the second object or the stage, similarly to the second object or the stage can be called the first object or the stage. As the first object or the stage, and the second object or the stage, both, are, respectively, objects or stages, but they cannot be considered to�to the same object or stage.

[0022] the Terminology used in this description of the invention, is intended only to describe specific embodiments of the invention and is not intended to limit the invention. With regard to the description of the present invention and the accompanying claims, the nouns referred to in the singular also mean the plural unless the context clearly indicates otherwise. You should also understand that used here, the term "and/or" includes and encompasses any and all possible combinations of one or more relevant components. You should also understand that used here, the terms "comprises", "comprising", "includes" and/or "containing", as used in this description, indicate the presence of the specified features, units, steps, operations, elements and/or components, but do not preclude the presence or addition of one or more other features, units, steps, operations, elements, components and/or groups.

[0023] for purposes of this description, the term "if", depending on context, can mean "when" or "after" or "in response to determining" or "in response to the detection. Similarly, the phrase "if it is determined that" or "if [a specified condition or event] is detected", depending tcontext, may mean "after the definition of" or "in response to definition, after the discovery of [a given condition or event]" or "in response to the detection of [a given condition or event]".

[0024] furthermore, it should be noted that the variants of embodiment of the invention can be described as the process shown in the form of block diagrams, functional diagrams, information flow, block diagrams or functional circuits. On the block diagram of the operation can be shown as a sequential process, however, many operations can be executed in parallel or simultaneously. In addition, can be changed the order of operations. The process ends with the completion of its operations, however, there may be additional steps not included in the figure. A process may correspond to a method, function, procedure, subroutine, etc. If the process corresponds to a function, its termination corresponds to a return of the function to the calling function or the main function.

[0025] in addition, for purposes of this description, the term "storage medium" may represent one or more devices for storing data, including read only memory (ROM), a storage device with random access (RAM), magnetic RAM, RAM, storage media for m�gnity disks optical storage devices, flash memory devices and/or other machine-readable media. The term "machine-readable medium" includes but is not limited to portable or fixed storage device, optical storage device, wireless channels and various other mediums capable of recording, storing and contain instruction (s) and/or data.

[0026] the present application discloses methods and apparatus to make practical application of marine seismic vibrator, are disclosed in concurrently pending application of the same inventor, entitled "METHODS AND SYSTEM SWEEP FOR MARINE VIBRATORS", the registration number IS 11.0203. The application IS 11.0203 included here in full by reference for all purposes.

[0027] Figure 1 shows seysmoregistriruyushchiye system 10 sea-based. In the system 10, a survey vessel 20 tows one or more seismic cables 30 (Figure 1 shows one seismic streamer 30) located behind the vessel 20. It should be noted that the streamer 30 can be positioned so that a lot of seismic cables 30 during towing was located in the same plane at the same depth. As another non-limiting example, provides for the towing of the seism�ical KOs on many different depths, for example, above/below the main line.

[0028] the length of the seismic cables 30 may be several thousand meters, they may contain various support cables (not shown), and connecting wires and/or circuit (not shown), which may be communication along seismic cables 30. Usually each seismic streamer 30 contains the main cable, which is mounted seismic sensors 58, which record seismic signals. Streamer 30 contain seismic sensors 58, which may be hydrophones, receiving information about pressure, geophones, receiving information about the movement, or multi-component sensors. For example, the sensors 58 may be multi-component sensors, with each sensor capable of detecting pressure Wavefield and at least one component of the particle motion that is associated with acoustic signals near the sensor. Examples of the component of particle motions include one or more component of the displacement of a particle, one or more component (longitudinal (x) lateral (y) and vertical (z) components (see axes 59)) the particle velocity and one or more component of the acceleration of the particle.

[0029] multi-component seismic sensor may include one or more hydrophones, geophones, sensors displacement of particles, sensors, particle velocity, Axel�of Romero, sensors differential pressure or a combination thereof.

[0030] Marine seysmoregistriruyushchiye system 10 includes one or more seismic sources 40 (Figure 1 shows two seismic source 40), for example, design or other sources. These seismic sources 40 may be associated with the research vessel 20 or to tow this vessel. The seismic sources 40 may operate independently of the survey vessel 20, that is, these sources 40 can be attached, as a few examples, to other vessels or buoys.

[0031] as a survey vessel 20 tows streamer 30, the seismic sources 40 generate acoustic signals 42 (an acoustic signal 42 shown in Figure 1), often called "shots", and send them down through the water column 44 into strata 62 and 68 beneath the bottom surface of the water 24. Then these acoustic signals 42 are reflected from the various subterranean geological formations, for example, shown in Figure 1 formation 65.

[0032] the Incident acoustic signals 42 generated by the sources 40, lead to the formation of the corresponding reflected acoustic signals, or pressure waves 60, which are detected by the seismic sensors 58. It should be noted that the pressure wave is received and detected by the seismic sensors 58, incl�Ute in "rise" of the pressure wave, moving to the sensors 58, not reflected from the boundary between the air-water 31, and "sinking" of the pressure wave formed by reflections of the pressure waves 60 from the interface air-water 31.

[0033] the Seismic sensors 58 generate signals (e.g., digital signals), called "traces", corresponding to the measured values of the pressure Wavefield and particle motion. It should be noted that, although the physical wave field continuously in space and in time, the traces are recorded at discrete points in space, which can lead to spatial distortion. These traces are recorded and may at least partially processed by the signal processing unit 23 that is installed on the survey vessel 20, in accordance with some embodiments of the embodiments of the invention. For example, a particular seismic sensor 58 may provide a trace, corresponding to the value of the wave pressure field obtained by its hydrophone; and the sensor 58 may also provide (depending on the configuration of the sensor), one or more marks corresponding to one or more components of the particle's motion.

[0034] One objective of seismic exploration is to build the image to scout the area in order to identify a subterranean geological formation, for example, geological formation 65. Pic�next analysis of this image can show the space of possible deposits of hydrocarbons in subsurface geological formations. Depending on the specific schema of the intelligence part of the image analysis may be performed on the seismic survey vessel 20, for example, using the device of the signal processing unit 23. In other schemes intelligence image processing may be done by the system seismic data processing (for example, the system 600 of processing seismic data is shown in Figure 6 and described below), which may be located, for example, in the office on land or on the vessel 20.

[0034] Specific seismic source 40 may be formed in the form of a system of seismic source elements (e.g., design or marine seismic vibrators), which can be strings (e.g., strings cannons) in this system. Specific seismic source 40 may also be formed from a single airgun or system from a given number of guns, and can be formed from many such systems, etc. Regardless of the specific composition of seismic sources these sources in the process of exploration can shoot in a specific temporal sequence.

[0036] Theoretically for seismic prospecting is possible to apply a pulsed sources or sources of continuous operation. In practice, when conducting seismic ground really well used, and a pulsed light source�Ki, and sources of continuous operation. However, when carrying out marine seismic exploration on an industrial scale sources of continuous action (for example, marine seismic vibrators) are almost never used. There are many characteristics of marine seismic vibrators, which prevent their practical application as seismic sources. One of these characteristics is their weak acoustic power compared to air guns, especially at low frequencies. The result of poor power at low frequencies can be deterioration of the seismic image to an unacceptable level. This feature is a weak power - means that in the process of exploration has a negligible impact on the environment, and this is advantageous from the point of view of environmental protection, especially the protection of marine fauna, which is one of the challenges when conducting seismic surveys. Unlike pulsed sources (e.g., design), which can emit a pulse, immediately covering the entire spectrum, the vibrator can vibrate consistently at each individual frequency spectrum, resulting in the energy of this source covers the entire spectrum. The amount of time required by the vibrator to make swiper�tion across the entire spectrum, limited production or operational requirements. This may also limit the full value of energy across the entire frequency spectrum.

[0037] Another aspect limiting the possibility of using marine seismic vibrators for marine seismic exploration, is the complexity of the process of reproduction of the marine seismic vibrator of the energy output spectrum corresponding to the spectrum of the traditional system design. To date, the use of marine seismic vibrators was not desirable, practical and/or feasible due to the need for complex organizations, for example, in the form of the system and method disclosed in the patent of the United States 6942059 entitled "Marine vibroseis system with a combined bandwidth", owned by the applicant of this application, designed to create this configuration of the marine seismic vibrator, which would allow the parameters of its output signal/sweep, equivalent to such options airgun or system design.

[0038] Figure 2 shows, for illustration purposes, an example of the energy spectrum Em(f) single-frequency output signal of the marine seismic vibrator. The output power is almost constant at frequencies above a certain frequency� the dam. In this example, such frequency is approximately 10 Hz. At frequencies below this frequency the dam output falls and, eventually, becomes insufficient for seismic exploration. This blockage may be due to the limited working range of the vibrator and may be proportional to the square of the frequency. For seismic prospecting may still need a part of the range (for example, several Hz) below this frequency the dam (e.g., 10 Hz). The horizontal segment of the curve in the frequency region above the dam may be due to limitations in the mechanism that controls the operation of the vibrator. Shown here is the energy spectrum of the output signal of the marine seismic vibrator is very different from the energy spectrum of the usual guns, one of which is shown in the Figure 5 curve 535, and will be discussed later. Using marine seismic vibrator is difficult to obtain the same energy spectrum as that of the airgun.

[0039] Figure 3 shows some values of SNR in the seismic image, where the data were collected by means of a system of pneumatic guns. Illustrating the correlation between the quality of the seismic image and various parameters of the process of obtaining seismic data. These data were taken from traditional two-dimensional seismic profile obtained in M�cikanka the Gulf through the system design. This same profile was also obtained without shots design (passive plot, using only noise), resulting in using the same process to create the image background noise. The image data is divided into one-second Windows, depending on the target depth in terms of TWT (TWT = double the running time, i.e. the time of the signal from source to receiver). One-second data Windows image transformed into the frequency range, and then divided by the noise spectra to obtain the values of SNR, as shown in Figure 3. Each curve (302 - 307) demonstrates the values of SNR for image in one-second window, for example, the curve 302 for Windows with TWT in 2-3 seconds, curve 303 for Windows with TWT in 3-4 seconds, a curve 304 for Windows with TWT in 4-5 seconds, the curve 305 for Windows with TWT in 5-6 seconds, the curve 306 for Windows with TWT in 6-7 seconds, and curve 307 for Windows with TWT in 7-8 seconds. Good quality image can often be considered as an image with a minimum value of SNR of approximately 20 dB. The value for SNR below 20 dB in some parts of the spectrum may degrade the seismic image, sometimes to an unacceptable level, the value of SNR, significantly exceeding 20 dB in other parts, there may not be any advantages for the resulting seismic image as a whole. For example, for 4-5 seconds TWT (304) at a frequency of 0 Hz is exceeded, the output signal above the noise is 32 dB, which is 12 dB more than required to obtain high-quality images with the requirement of 20 dB. For small targets (e.g., 4 seconds TWT) the value of SNR 20 dB is provided in a fairly large range (in this example, from approximately 12 Hz and above). For the purposes with TWT in 4-5 seconds (304), for example, the value of SNR 20 dB is provided in a slightly more narrow range roughly between 15 Hz and 70 Hz. If targets are located at a greater depth (305, 306 or 307), the SNR value will be insufficient to achieve the quality level of 20 dB. If for small targets SNR values greatly exceed the required image quality, for deeper targets (with TWT over 6 (C), the SNR value may be insufficient.

[0040] Figure 3, where the source is aircannon, you can see that the energy density is distributed unevenly. At the high frequency end of the spectrum aircannon gives more energy than is necessary to obtain images with sufficient quality, i.e. the desired value of SNR. Energy spectrum of the devices is not optimal for seismic imaging. To obtain a seismic image with a given image quality is not required to compare the spectrum of energy density of the vibrator with the spectrum of the energy density of pneumatic guns. In other words, in the case of application�of marine vibrators and their spectra do not necessarily have to match the design spectra. Marine seismic vibrators can be used to obtain specific spectral energy density based on the result of the quality of the seismic image, not from the spectral characteristics of the devices. This is based on the quality of the image energy distribution of the spectrum or the sweep function may be more useful and effective.

[0041] According to the present invention, the operation of the marine seismic vibrator (vibrator) can be implemented/monitored in such a way as to carry out seismic sweep/sweep function with a configuration which allows to obtain the required quality and/or based on it, not to conform to the typical output energy of the system design or create a standard uniform spectrum. In accordance with the methods and apparatus described below, by creating a configuration of marine seismic vibrators, based on the requirements for image quality or other quality requirements, you can make a marine vibrator capable of providing sufficient energy for seismic exploration. The following aspects of these methods function sweep for marine seismic vibrator may be designed based on the requirements for image quality and/or requirements�tions, concerning the impact on the environment. This way you can create the configuration of the marine seismic vibrator, allowing seismic sweep with more favorable environmental impacts than the source in the form of airgun. In addition, the modes sweep in the process of seismic exploration can be modified to meet changing conditions of noise and/or impact on the environment.

[0042] To facilitate further consideration of the image quality determined by the SNR value will be set conditional level, for example, 18 dB. Depending on the requirements or further use of the resulting image this level of SNR that determines the image quality can be set higher (e.g., 20 dB, as previously used) or lower. You can define a sweep function that will give this value of SNR within the widest possible frequency range. The value of SNR, you can choose to make a function of frequency.

[0043] Figure 4 shows three functions sweep for marine vibrators, and Figure 5 shows their corresponding energy curves in terms of SNR. In Figure 4 the horizontal axis is measured the time (in seconds) in linear scale, while the vertical axis is frequency (Hz) in logarithmic scale. Blue curve 410 illustrates whether�eyny sweep (i.e., meaning, that frequency is a linear function of time), which is the traditional scheme sweep to vibrators; red curve 420 is the sweep corresponding to the spectral characteristics of the airgun, and the orange curve 430 is a sweep based on the requirement that the value of SNR in the image was 18 dB. Sweep under the orange curve 430 corresponds to a given SNR requirement at the required/specific depth targets and minimizes the excess radiation of acoustic energy. By sweep under the orange curve 430 vibrators can give the best image quality among the three curves sweep 410, 420 and 430. In addition, synergistically, sweep mode, represented by the orange curve 430, less impact on the environment than the other two.

[0044] Figure 5 shows equivalent levels of energy source in dB for a sweep modes, shown in Figure 4, and the energy level of background noise. The horizontal axis is frequency in Hz on a logarithmic scale and the vertical axis is the energy of the source in dB. Black dotted curve 502 shows the energy spectrum of background noise, equivalent measured in the examples shown in Figure 3. Data processing from the source of noise of the same level gives the same picture�of noise, as in Fig. 3. To achieve a constant image quality with 18 dB energy curve of the source can be orange dotted curve 532, exceeding the background noise curve 502 18 dB. The solid blue curve 510 shows the linear sweep; the solid red curve 520 - sweep struggling to meet energy airgun array, which is represented by the dotted red curve 535 extending beyond both edges of the solid red curve 520. Because the sweep time in this example is limited to 5 seconds, the marine seismic vibrator may not cover the entire range of 535 airgun. In some operations to get information from the deeper purposes of the sweep may last for 10, 15 seconds or longer. In these cases, the bandwidth can also be expanded in the direction of low frequencies or high frequencies, or routes. Solid orange curve 530 represents the sweep carried out under curve for SNR of 18 dB. Figure 5 shows the spectral energy density for targets with TWT in 4-5 seconds.

[0045] for a known level of background noise, shown as black dotted curve 502, sweep, providing a constant value of SNR, is simply orange dotted curve 532, obtained by adding the required SNR, i.e., 18 dB, Phono�WMD noise. Background noise 502, as shown in this example, contains a large barrier frequency higher than approximately 80 Hz, which is the result of the depth at which was the source used in the test for obtaining information according to Figure 3, and demonstrates stable growth while reducing frequencies below approximately 20 Hz. The noise level 502 source is the level, in which case its radiation source and subsequent processing in the image is similar to the processing of the signal would give the image noise level corresponding to the level observed in the image test, which resulted in the curves in Figure 3. Curve 502 is the image noise, expressed as the equivalent level of the source.

[0046] When the linear sweep 510 (blue line) energy is distributed over a wider range from approximately 5 Hz to 83 Hz. However, the frequency range in which the value of the SNR remains at the level of 18 dB, is approximately 19-80 Hz. On the low-frequency edge of the energy value of the source is kept stable up to approximately 10 Hz, and then decreases, while the energy of noise is steadily increasing; the value of SNR at low frequencies declines rapidly. In the case of this type of sweep for seismic exploration operating frequency range is approx�tive 19-80 Hz. Curve sweep 517 at the bottom of Figure 5 illustrates that the sweep covers the entire frequency range from 5 Hz to 83 Hz with equal time on all sites.

[0047] In the sweep mode 520, imitating airgun range (red line), the energy source decreases with decreasing frequency at low frequency edge. In order to cover the entire range, without going outside the 5-second duration of the sweep, the range of covered frequencies should be less than with a linear sweep 510. In this case, the sweep range is from about 12 Hz to 70 Hz (see bottom red line 527). During almost the entire process of the sweep SNR exceeds the set value of 18 dB. The range of frequencies used in the low frequency region is expanded to the value of 12 Hz in contrast to 19 Hz - the linear sweep 517. In the case of real airgun range has expanded to matching the dotted lines 535, ending approximately at a frequency of 5 Hz. The spectral range will increase, but the used spectral range (i.e., range from requirements that the SNR exceeds 18 dB) in this example will remain virtually the same.

[0048] In the case of sweep 530, providing a constant value of SNR (orange line 530), the band of frequencies covered will be the Chi�Oka - approximately from 9.5 Hz to 70 Hz. In this case, the lion's share of the duration of the sweep will be devoted to the passage of the low-frequency region, where energy demand is greatest, and the power of the vibrator is most limited. For example, the vibrator requires only one second to pass the lowest band of frequencies approximately from 9.5 Hz to 10 Hz, and 4 seconds to pass all frequencies below 16 Hz, while the higher band of frequencies 16-70 Hz traversed in one second. In the sweep mode 530 used frequency range is approximately from 9.5 Hz to 70 Hz. The low-frequency region extends to below 10 Hz in contrast to the sweep mode the devices 520, where it is 12 Hz, and linear sweep 510, where it is 19 Hz.

[0049] Sweep 530 is highly nonlinear. In this example, the vibrator takes 4.2 seconds (approximately 85% of all 5-second duration of the sweep) on the passage of the low-frequency band 9.5 to 18 Hz (8,5 Hz, or approximately 15% of the entire band width of 61.5 Hz); and the passage of the remaining bands of higher frequencies 18-70 Hz 52 Hz or approximately 85% of the total band width of 61.5 Hz) spends 0.8 seconds (approximately 15% of the duration of the sweep).

[0050] Sweep 530 differs from the mode of operation of the marine seismic vibrato�and, when it is used to implement traditional linear sweep 510 or 520 sweep, designed to conform to the system of pneumatic guns (red line). In the implementation of the last two options sweep 510 and 520 using a marine seismic vibrator radiates too much energy at medium and high frequencies, for example, at frequencies above 17 Hz. At low frequencies, e.g. below approximately 17 Hz in the sweep process 510 and 520 is radiated too little power. These modes sweep do not provide the necessary/the required value of SNR over the range of frequencies used.

[0051] In the examples shown in Figures 4 and 5, the duration of the sweep is limited to 5 seconds. Increasing the duration of the sweep will increase the amount of available energy and to extend the covered frequency range.

[0052] Method 700 can be briefly represented as a block diagram, shown in Figure 7. Method 700, in which the use of a marine seismic vibrator may be carried out as follows:

- getting requirements for quality, e.g., SNR values than the background noise in the image, bandwidth used to obtain the image (710);

- set sweep function, based on the requirements to the quality of the image, for example, with�twelve energy curve, than the background noise of 18 dB (720);

- manage the operation of the vibrator in accordance with the sweep function (730) and data collection.

[0053] a quality Requirement may be a requirement for the quality of the final image, for example, a given value of SNR. A quality requirement can be defined as a set of functions of frequencies, not necessarily related to the SNR. A quality requirement may be a requirement concerning the impact on the environment, for example, the marginal value of energy emitted in a certain frequency range, for the purpose of protecting marine mammals or limit excessive radiated energy. When using the values of the SNR value of the background noise image can be obtained by direct measurement of noise and approximation to the method of processing, as in the example described above, or from the experience of previous studies in a similar area of exploration, with similar weather conditions and equipment to conduct reconnaissance. Direct measurement can be done before the intelligence, as in the example described above. Direct measurement of noise can also be implemented in the course of exploration in real time, i.e. to allow the sensors to record the signals in a time when the sources are not activated. The sweep function can be defined�th based on the noise level, measured in real time.

[0054] the Level of background noise can also be estimated on the basis of General information relating to the scheme of exploration. A quality requirement may represent a compromise between different requirements, for example, the factor for the calculation of the sweep may include geophysical objectives: (1) required to image the value of SNR; (2) the lower and upper limits of the frequency band to obtain the image; (3) environmental goals, including, but not limited to, minimizing impact on the environment, for example, by minimizing excessive radiation of acoustic energy.

[0055] In one embodiment of the invention the sweep mode for the marine seismic vibrator/system of marine seismic vibrators may be carried out to conduct reconnaissance using estimates of the noise spectrum, seismic response of soil, SNR, processing sequence and/or requirements concerning the impact on the environment. In other embodiments, embodiments of the invention scheme sweep for marine seismic vibrator/system of marine seismic vibrators can calculate/determine/process in the process of exploration, using recordings of noise, SNR, performance sweep and/or �odobnye measured information, for example, at the beginning and/or at the end of each seismic sweep. In the same way it is possible to carry out an audit of the sweep mode during seismic exploration, based on the specific noise conditions observed during the reconnaissance. The sweep mode can also be modified to meet varying local requirements concerning the impact on the environment, for example, the actual habitats of marine mammals in this area during the seismic survey.

[0056] during the operation, can be used more than one seismic vibrator, for example, many sources 40, shown in Figure 1. These vibrators can be positioned at different depths (for example, separation by depth) or along the line of the desired wave field formation, or perpendicular to this line.

[0057] For simplicity of illustration, Figure 1 shows only the towed unit for marine seismic exploration, which is only one of many possible installations for marine seismic exploration. In the towed unit for marine seismic exploration, one or more vessels are towing as sensors and sources, moving in the process of exploration with the towing vessels. As already mentioned, many other possible types of installations for marine seismic exploration. In some�s of these installations, the sensors in the process of exploration can be stationary or moving. Sources (for example, marine seismic vibrator) in the process of exploration can also remain stationary or move.

[0058] Some of the above methods are easier to understand by using mathematical formulas. Scheme sweep for marine seismic vibrator can be developed based on the required quality of the resulting seismic image. The energy spectrum of a system of marine seismic vibrators in the downward direction, eliminating the effects of reflections from the sea surface can approximately be represented as:

where Em(f) is the energy radiated by a single dipole, if it is constantly running at the same frequency f. Em(f) is a characteristic of the vibrator, which can vary from vibrator to vibrator. One example is shown in Figure 2. N is the number of vibrators.

[0059] If the energy spectrum S(f) is defined, you can define and dt/df, and hence f(t), i.e. the sweep function. For linear sweep df/dt is a constant. If a vibrator is used to simulate an airgun, then S(f) is the energy spectrum of the devices shown curve 535 Figure 5. The sweep function, which provides the generation of this energy spectrum, also shown in figures 4 and 5.

[0060] In operation, the existing value of the length�eljnosti sweep and the number of marine seismic vibrators in the system of vibrators limit the frequency range, within which the sweep bandwidth, conducted marine seismic vibrators can meet the specified requirements to the energy spectrum, for example, f(tmax)=fmaxthen f(0)=fmin. For example, to implement the desired sweep, this is what provides the system design, the work of the marine seismic vibrator may be performed in this mode to obtain a spectrum corresponding to a certain upper frequency of the desired sweep. Then sweep can be sent from the high frequencies down to the end of the duration of the sweep. As a result, the duration of the sweep sets the limit on the lower frequency boundary of a spectrum sweep; below this border requirements will not be met. This is illustrated in Figure 5 (red curve 520). If you set the maximum frequency of 70 Hz and a duration of ≤ 5 seconds, minimum frequency, which can reach sweep is limited to a value of approximately 16 Hz. For the extension of the frequency range (for example, lowering the minimum limit for the frequency and increase the duration of the sweep, however, increasing the duration of the sweep can reduce the performance of the intelligence.

[0061] In some embodiments, embodiments of the invention in seismic exploration can�t be accessed by using more than one system of vibrators. In such cases, the methods of calculating the sweep circuit can be applied to each system of marine seismic vibrators. Marine seismic vibrators can be placed in a certain range of depths, and methods discussed here can be applied to any depth.

[0062] In some embodiments, embodiments of the invention, a new system of marine vibrators can be formed from existing vibrators. This system of marine vibrators can be used as a source for marine seismic exploration. The system of marine vibrators comprises at least one marine seismic vibrator. The control unit of the vibrator is connected to the system of vibrators, wherein the control unit vibrator may control the operation of the vibrator to implement sweep over a range of frequencies in accordance with one or more functions of the sweep. The sweep function can be based on the quality requirements. The sweep function can be a function of frequency. A quality requirement can be any of the above-mentioned quality requirements. The control unit of the vibrator can be a dedicated control unit or part of the control system, which controls the exploration. The system of vibrators can tow the ship dedicated to your source, or seismic court�about, towing a marine streamer to conduct reconnaissance.

[0063] the examples Described above are based on two-dimensional observational data. However, in the case of applications for three-dimensional exploration of the advantages of the above described methods and apparatus can be more significant, because the rate of accumulation is higher. The above-described method and apparatus can be applied equally in this case.

[0064] the Methods and apparatus described in the application with registration number IS11.0203 pending concurrently with the present application, make the application of marine seismic vibrators feasible. However, there are still some problems that hinder the conduct of marine seismic surveys with sources of continuous operation. Unlike continuous sources (e.g., vibrators), used for land seismic exploration, where the sources are located in a stationary position during vibration, in some cases, marine seismic sources are moved considerable distances in the process of vibration, i.e. at the time when the emission of signals. Usually when conducting a marine seismic survey vessel tows sources and receivers at a speed of approximately 2.5 m/s during a 5-second swiper�ing the ship (and all sources and receivers) is 12.5 m; during a 10-second sweep it runs 25 m. These distances cannot be neglected when order resolution seismic imaging is meters.

[0065] To visualize the process of blurring consider the linear sweep occurring in the form of generation of the signal with increasing frequency from 5 Hz to 75 Hz for 10 seconds. Component of the image obtained at a frequency of 75 Hz, and the component at frequency 5 Hz generated by sources that actually moved of 25 m. it is Possible to present a collection of separate single-frequency images, each of which will have different offset blur. For example, the image obtained at a frequency of 75 Hz, will be offset by 25 m relative to the image obtained at a frequency of 5 Hz. You may need to adjust (for example, cleaning). Cleaning is to shift the image to the corresponding distance and stack them, although it is not necessary to perform this way.

[0066] the Adjustment (clearance) in principle can be performed directly, but this may be hampered by two things: (1) data are obtained with an insufficient sampling frequency in the General range of the receiver, which is usually performed and cleaning, and (2) the output signal of the vibrator may contain distortions (harmonics). One advantage marine use (above ground) consists� in what is the shape of the original pulse, including harmonics, it is possible to accurately measure, for example, using the nearby hydrophones.

[0067] the Phase error caused by the blur when the vibrator sinusoidal signal may be a phase shift due to the distance between the nominal firing position x0 and x(f), in which the vibrator emits at the considered frequency. This phase error can be expressed as:

ur.1

where:

E (f, TOA) is the phase error at frequency f and the angle of the exit signal TOA,

B(f) is the amplitude of single-frequency generation of the vibrator at a frequency f,

x(f) is the position from which the radiation is at a frequency f,

x0 is the nominal firing position,

dt/df(f) is the reciprocal of the speed of the sweep at a frequency of f

TOA is the angle of the output signal (relative to the vertical) toward the far field.

[0068] If the function f(t) is selected, the phase error can be estimated in the range of angles TOA for each frequency sweep. The biggest error on the TOA range can be used as the error for the given frequency. Figure 8 shows the phase error curves for several different functions sweep.

[0069] the error Criterion can be set as the maximum amp�itude and phase error. For the examples considered below the threshold error set in recovery mode from convolution and clearing of a blur (if applicable) pulses from the far field at angles of output signal (TOA) between 0 (vertical) and about 22 degrees. This range TOA selected as typical of the signal included in the geological environment, and for illustrative purposes. The criteria for the admissibility of error may be as follows: the error signal source in the far field does not exceed 3.4 degrees in phase and 0.5 dB for the value of energy throughout the range of the TOA. These criteria leave a margin of error of approximately 6% in amplitude of the signal, i.e. no higher than 24 dB at the level of the shot. These arbitrarily chosen threshold of error taken to facilitate consideration. Valid threshold error values can be selected on the basis of the many schemes of exploration or qualitative parameters.

[0070] the following examples the duration of the sweep is 5 or 10 seconds, and the penetration depth is 8 m. These examples are illustrative, and can be used any other values of the length and depth of the implementation.

[0071] described Below are several sweep modes, including the usual "linear frequency" sweep (blue curve, for example, 830 in Figure 8), which is podrazumeva�, that the fundamental frequency is a linear function of time; linear sweep wave-length (red curve, for example, 806, 812, 816 and 822), implying that the primary wavelength is a linear function of time; sweep "with a negligible error (e.g., 803 or 804), implying that the phase error less than the threshold value of the error (i.e. negligible), and the cleanup can not be performed; and sweep "on the basis of the SNR (e.g., 840), implying that the sweep function is selected on the basis of a certain the signal-to-noise ratio (SNR) in the image or based on another criterion, based on the quality of that described in the application, located on the simultaneous consideration with the present application, with the registration number IS11.0203, which is included here in full for all purposes.

[0072] Figure 8 shows the phase error for several different variants of sweep duration of 5 seconds. The top graph shows the phase error as a function of frequency and time for a sinusoidal sweep of the vibrator; the lower graph of phase error is shown as a function of wavelength and time sweep for a similar sinusoidal vibrators. In these examples, assume that the radiators radiate only at the fundamental frequency, i.e., the sources emit only�on a single frequency at any one time in accordance with the sweep function, and each frequency is emitted from only one position. The dotted curves 820, 815, 810, 805 and 803 are curves with constant phase error, the phase error are, respectively, 20 degrees, 15, 10, 5 and 3.4 degrees. For example, the curve 820 illustrates a curve with a constant phase error of 20 degrees during the sweep process. Curve 803 illustrates a curve with a constant phase error of 3.4 degrees. This curve 802 may be a function of the sweep, and if the vibrator is held on the frequencies according to this curve, the total phase error in the result image is the value of 3.4 degrees, which can be neglected for many purposes.

[0073] On the same upper diagram in Figure 8 shows the other two curves sweep: blue curve 830, representing a linear frequency sweep, and the orange curve 840 - sweep based on the SNR. As shown in this chart, if used linear frequency sweep 830, then the phase error will be significant on most frequencies. For example, for frequencies between 50 Hz and 25 Hz phase error exceeds 20 degrees. For a small number of the upper frequencies (above 70 Hz) or the lowest frequencies (below approximately 5 Hz) phase error is close to a negligibly small level (i.e. 3.4 degrees) or below.

[0074] �as this chart shows although sweep 840 is selected on the basis of the quality of the image, its phase error at most frequencies is quite small. In this example, at high frequencies, greater than about 15 Hz, the phase error can be negligible (e.g., below a threshold of error of 3.4 degrees). For frequencies between 15 Hz and 12 Hz phase error amount to 4-10 degrees. And only at frequencies below about 12 Hz these phase errors become significant, i.e., greater than 10 degrees. If the sweep function sweep is applied 840, it may need cleaning for frequencies below approximately 15 Hz or for time sweep after 1 second. On the low-frequency edge (i.e., below approximately 15 Hz) failure of selection or distortion of information may not be a problem. Therefore, clearing of blur can be done much easier in this sweep mode than in the case of high frequencies and problems with misrepresentation.

[0075] the lower diagram of Figure 8 illustrates such a phase error, but in the range of wavelengths. On this bottom diagram of the Figure 8 curves 804, 806, 812, 816 and 822 are curves with a constant phase error, respectively, 3.4, 5, 10, 15 and 20 degrees. Blue curve 832 represents a linear frequency sweep, and the orange curve 842 - sweep�established that chosen based on the SNR. The green curve 804 represents the sweep phase error of 3.4 degrees, which can be considered negligible error for many purposes, and cleaning of the blur may not be performed.

[0076] the Green curve 804 curve or sweep "with negligible blur" can roughly be described in the form f(t)=15/t, where f is frequency in Hz, t is the time in seconds, and the threshold value of the phase error is set at 3.4 degrees; or more generally f(t)=4,4<φ/t, where φ is the acceptable value of the phase error in degrees.

[0077] If the marine seismic vibrators emit signals without distortion, as in the examples in Figure 8, the cleaning process of blurring can be performed as described above. In some cases, the choice of certain functions sweep can make cleaning unnecessary.

[0078] Figure 9 compares the sweep presented on the Figure 8, with swierklany with the application of the cleaning process. In these examples, the assumption that the sources do not emit distortion, i.e. the harmonic frequencies. The dotted curves 930, 940 903 and illustrate the error (phase error - the upper diagram, amplitude error - the lower graph) for a linear sweep frequency sweep based on the SNR and sweep with negligible blur. In the case of prima�in termination of the cleaning process, all of the phase error can be corrected, as shown in solid curves 932, 904, 942 Figure 9. The amplitude errors 950 negligible even without correction cleaning in these examples, where there is no distortion, while the threshold value 955 amplitude error is set at 0.5 dB. Sinusoidal cleaning can completely fix errors for a sinusoidal vibrator.

[0079] Many vibrators in addition to the sinusoidal output signal can generate harmonics. Unlike vibrators used for land seismic exploration, the actual signals from the sources can be observed by using accelerometers placed on the vibrator.

[0080] Due to harmonic distortion, when the sources can emit each frequency from several different positions, the cleaning process will be more complex than in the absence of harmonic distortion. For example, the source can emit at a frequency of 60 Hz in a position where the sweep mode requires a 60 Hz, but it can also radiate 60 Hz as harmonic when the sweep mode requires 30 Hz, 20 Hz or 15 Hz, etc. If you apply a sinusoidal cleaning, it is assumed that all the energy frequency of 60 Hz is emitted at the position X1 where the sweep mode requires 60 Hz. This leads to the error due to the harmonic of the nth order for non-vertical radiation because the energy of the same frequency emitted � positions X2 (30 Hz), X3 (30 Hz), X4 (15 Hz), etc. the Error signal associated with the position of the harmonics can be expressed as in Equation 2. If cleaning is not carried out, then the remaining error can be expressed by Equation 3. Equation 3 becomes Equation 1, if A(i) is set to zero for i>1, i.e., for a sinusoidal source.

ur.2

where:

B(f) is the basic amplitude single-frequency generation of the vibrator at a frequency f,

n is the order of harmonics,

A(n) is the complex amplitude of the harmonic of the nth order of a given pulse, A(1)=1,

x(f) is the position where the radiation at frequency f,

dt/df(f) is the reciprocal of the speed of the sweep at a frequency f. If this value is divided by the order of harmonics, we obtain dt/df for this harmonic.

ur.3

where x0is the nominal position for firing. All other symbols are the same as in Equation 2.

[0081] Figure 10 illustrates a comparison of options option presented on Figure 8, and, in the case of the use of cleaning processes, as in Figure 9. Unlike the examples presented in Figure 9, in these examples the Figure 10 the assumption that the sources actually generate and distortion, i.e. the frequency of the harmonics. The magnitude of distortion that represents the relationship of the energies of all harmonics � energy of the fundamental frequency, in these examples constitute approximately 7.9%. In the presence of these harmonic distortion of phase error and amplitude error for a linear sweep in frequency (blue curve 1030, 1032) and the sweep-based SNR (orange curve ==1040, 1042), will not be negligible, therefore, needs to be cleaned. Even after cleaning, the phase error is not fully corrected (1033, 1043). For linear sweep curve of phase error 1033 increases from approximately zero degrees at a frequency of approximately 20 Hz to 8 degrees at a frequency of 75 Hz. For sweep-based SNR 1043 even after cleaning, the phase error is approximately 4 degrees in the frequency range approximately from 28 Hz to 50 Hz and becomes infinite at 70 Hz. To sweep "with negligible blur 1003 and 1004, these errors will be larger than in the latter examples. In these embodiments sweep "with negligible blur" phase and amplitude errors still remain small enough to be neglected. Amplitude uncertainty for linear sweep 1034 has a value that cannot be neglected at frequencies above 40 Hz even after cleaning, or a cleaning process may not adequately correct these errors due to harmonic distortion. To sweep based On�W or sweep with negligible blur amplitude error 1044 1006 and remain negligible.

[0082] Obviously, the linear frequency sweep is not an optimal sweep function for marine seismic vibrator. In the presence of significant blur or harmonic distortion data obtained using linear sweep in frequency, can contain large errors, even after the cleaning process. Sweep, selected on the basis of SNR, can provide data with fewer errors, and most of these errors can be corrected by the cleaning process. Sweep "with negligible blur can provide the data that contains only negligible error, and in the processing of these data may not need to use the cleanup process.

[0083] In the case of a source of continuous operation, for example, marine seismic vibrator or land seismic vibrator, often use deconvolution to compress the required data in the time range. Before the implementation of the deconvolution process of the required seismic data may require cleaning. As shown above, in the case of sweep "with negligible blur the errors are sufficiently small value, whereby the cleaning process is not required. In the case of other variants sweep error may not be negligible�, and cleaning may be required. In many operations harmonic distortion is a common phenomenon, as shown in Figure 10, it is observed in cases when the vibrators generate harmonic frequencies in addition to the basic frequency, which conducted the sweep. Cleaning from revaluation shall be based on the knowledge of what frequencies are being radiation in any provisions. Cleaning compresses the source in space.

[0084] Deconvolution of the original pulse source is carried out by evaluating the original pulse source. Theoretically cleaning and deconvolution can be performed on the same stage and transform data into a form which would be obtained in case of application of a pulse source in the nominal positions of the shooting. However, it may be easier if done by two simplified steps: 1) "deconvolution ignoring blur" followed by 2) "sinusoidal removal of blur".

[0085] it Should be noted that for higher frequencies require more accurate position of the source than for lower frequencies. As shown in these examples, sweeping is best carried out with the upper to the lower frequencies. During the ground reconnaissance vibrators usually carry out sweep up in frequency, resulting in errors when estimating the shape of the original pulse �roadside before (there where the signal is stronger).

[0086] As shown in Figure 11, the method 1100 can be briefly summarized as follows:

- the selection criterion for the validity of the magnitude of defocus (1110);

- the choice of nonlinear functions frequency sweep from top to bottom (1120);

- calculation of quantities of the blur for each frequency (1130);

- implementation of vibrators work in accordance with the sweep function (1140);

- obtaining marine seismic data (1150); and

- performs cleaning of the data obtained for frequencies where the magnitude of blur exceed the above criteria (1160).

[0087] After correcting the blur data can be further processed for other purposes, for example, further processing of data for seismic imaging, seismic modeling, seismic interpretation, etc.

[0088] it Should be noted that not all steps in method 1100 are necessary. For example, if the sweep function selected in accordance with criteria acceptable blur, for example, sweeping "with negligible blur, the blur in the resulting data will be at the level of the error criterion or below. The magnitude of the blur is not required to calculate, and no purification is required. Steps 1130, 1160 are not required.

[0089] If the curve of the selected function of the sweep curve is below the allowable Zn�values blur in some of the above examples is approximately 15/t, for example, if we choose f(t)<15/t, the resulting levels of blur would be lower distortion criteria. In this case, cleaning is also required.

[0090] For the process of data acquisition marine seismic survey may not be required to perform actions on data processing. The obtained data can be processed later by a separate data processing operation. In this case, in the process of obtaining data the calculation of the blur values (1130) and the clean (1160) are not required. During the process of data processing with the known functions of the sweep and the corresponding received data, the magnitude of defocus can be calculated and compared to the criterion for the validity of the blur. If necessary, the cleaning operation can be performed in the data processing.

[0091] In the case of a sweep function based on the SNR blurring occurs only at low frequencies (e.g. below 15 Hz), so cleanup is required only at low frequencies.

[0092] the Criteria for permissible blur and sweep function is chosen to carry out marine seismic surveys or during its implementation. If you have selected the proper function of the sweep, the problems with the blur can be avoided, and the cleaning process is not required. In this case, the process� data processing can be performed so, as if problems with blur and was not.

[0093] Qualified specialists in this field will be clear that you can combine one or more steps of the above-mentioned and/or change the order of some operations. Moreover, some operations can be combined with other aspects described herein embodiments of the invention and/or change the order of execution of some operations. The process of measurement, interpretation and action operators can be implemented in a cyclical manner; this concept is applicable to the methods described herein. Finally, part of the methods can be implemented using any suitable technology, including automated or semi-automated work on the basis of the computer system 600 shown in Figure 6.

[0094] Part of the above-described methods can be implemented using a computer system 600, one example of which is shown in Figure 6. The system computer 630 may be associated with disk storage devices 629, 631, 633 and 635, which may be external storage devices hard drives and measuring sensors (not shown). Provided that the disk storage device, 629, 631, 633 and 635 can be traditional media on hard drives, so they can be involved with local information�Noah network or remote access. While disk storage devices are shown as separate devices, for storing any or all of the control program, data, measurements and results, if desired, can be used one disk storage device.

[0095] In one embodiment of the invention provides that the sensor data are received in real time, can be stored in disk storage device 631. Different data from different sources in real time, can be stored in disk storage device 633. The system computer 630 may retrieve the appropriate data from the disk storage device 631 or 633 for processing data according to the control programs corresponding to the different embodiment variants described here. Control programs can be written in the programming language of the computer, such as C++, Java, etc. Control programs can be stored in a computer-readable carrier, for example, in a disk storage device 635. Such computer-readable media may include computer storage device.

[0096] In one embodiment of the invention the system computer 630 may output the output information mainly on the graphic display 627 or through the printer 628 (not shown). The system computer 630 may keep�ü results obtained using the methods described above on disk storage device 629 for the purpose of their further use and analysis. The system computer 630 may be equipped with a keyboard 626, and a pointing device (e.g., mouse, trackball, etc.) 625 for work in interactive mode.

[0097] the System computer 630 may be located at the venue of intelligence, for example, may be part of the control unit 23 on Board 20, as in Figure 1. The system computer 630 may be associated with equipment conducting exploration for different measurements. Such data after conventional formatting and other initial processing can be recorded by the system computer 630, the disk storage device 631 or 633 in the form of digital information for later retrieval and processing as described above. In Figure 6 the disk storage device, for example, 631, shown directly associated with the system computer 630, however, access to this disk storage device may also be provided via local area network or remotely. Furthermore, while disk storage devices 629, 631 shown as separate devices for storing input data and results of the analysis, however, these disk storage �disorder 629, 631 can be implemented within a single disk media (together with disk unit 633 for storing programs or separately) or any other traditional method, known qualified specialists in the field to which the present invention relates.

[0098] Although the above examples described only several embodiments of the present invention, qualified specialists in this field can easily see the opportunity for many modifications of these embodiments of the invention that do not lead to the exit outside the scope of the invention. Accordingly, it is contemplated that all such modifications are included in the scope of the present invention defined by the attached claims. The claims relating to the devices and their functions, should cover the design described here as performing the specified functions, and not only structural equivalents, but also equivalent structures. That is, although a nail and a screw may not be structural equivalents, because the nail has a cylindrical surface intended for fastening wooden parts with each other, and the screw has a spiral surface, however, to perform the function of fastening wooden parts to each other, a nail and a screw may be ek�Valentine designs.

1.The method of operation of the marine seismic vibrator as a moving source for marine seismic exploration, including:
the choice of nonlinear functions used for sweeping the frequencies from top to bottom on the basis of criteria acceptable blur;
bringing marine seismic vibrator in accordance with this feature of the sweep; and
receiving data of marine seismic exploration.

2. A method according to claim 1, characterized in that it further includes:
the data processing marine seismic exploration to determine the properties of the underlying Land.

3. A method according to claim 1, characterized in that the criterion of acceptable blur includes the threshold value of the phase error and the threshold value of the amplitude error.

4. A method according to claim 3, characterized in that the non-linear sweep function f(t) performing frequency sweep from top to bottom, while the expression in the time-frequency range is a function of not exceeding criterion of acceptable blur.

5. A method according to claim 4, characterized in that the threshold value of the phase error φ is in degrees, and the sweep function is a function, not exceeding 4,4 φ/t.

6. A method according to claim 1, characterized in that it further includes:
computing a blur value for each frequency�; and
clearing the data obtained for frequencies at which the blur value exceeds the criterion.

7. A method according to claim 6, characterized in that the sweep function is a function based on the quality requirements.

8. A method according to claim 6, characterized in that the quality requirement is a requirement to adhere to a predetermined value the signal-to-noise ratio (SNR) over the entire frequency band used for image acquisition.

9. A method according to claim 8, characterized in that the cleaning is carried out at a low frequency edge of the received data up to 20 Hz.

10. Installation for marine seismic exploration, comprising:
at least one marine seismic vibrator configured to implement the sweep of acoustic energy from the upper to the lower frequencies; and
the control unit of the vibrator is controlling the operation of the vibrator;
the control unit of the vibrator includes a function of sweep, which causes the vibrator to pass frequencies in accordance with the sweep function, wherein the vibrator is moved; and
the sweep function is based on criteria acceptable blur.

11. Apparatus according to claim 10, characterized in that it further comprises:
at least one marine seismic braid with a marine seismic sensors; and
the seism�cal ship towing at least one seismic braid;
in the process of operation of the marine seismic vibrator seismic streamer receives seismic data.

12. Apparatus according to claim 10, characterized in that the criterion of acceptable blur includes the threshold value of the phase error and the threshold value of the amplitude error.

13. Apparatus according to claim 12, characterized in that the non-linear sweep function f(t) performing frequency sweep from top to bottom, expressed in the time-frequency range, is a function not exceeding criterion of acceptable blur.

14. Apparatus according to claim 11, characterized in that it further comprises a processor, a configuration which allows to process the received seismic data to determine the properties of the underlying Land.

15. Machine-readable media containing machine-readable programs, the implementation of which by a processor induces a moving marine seismic vibrator to emit seismic energy in accordance with the function of the sweep, the sweep function is a nonlinear function of performing frequency sweep from top to bottom on the basis of allowable blur.

16. Machine-readable medium according to claim 15, characterized in that the criterion of acceptable blur contains the threshold value of the phase�ow error and the threshold value of the amplitude error.

17. Machine-readable medium according to claim 15, characterized in that the non-linear sweep function f(t) performing frequency sweep from top to bottom, expressed in the time-frequency range, is a function not exceeding criterion of acceptable blur.

18. Machine-readable medium according to claim 15, wherein said executing machine-readable instructions by a processor causes the processor to:
to calculate the amount of blur at each frequency; and
to perform the purification of the obtained data for those frequencies at which the magnitude of defocus exceeds the criterion.

19. Machine-readable medium according to claim 18, characterized in that the sweep function is a function based on the quality requirements.

20. Machine-readable medium according to claim 18, characterized in that the quality requirement is a requirement to adhere to a predetermined value the signal-to-noise ratio (SNR) over the entire frequency band used for image acquisition.

21. Machine-readable medium according to claim 20, characterized in that the cleaning is carried out at a low frequency edge of the received data up to 20 Hz.



 

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1 dwg

FIELD: measurement equipment.

SUBSTANCE: invention relates to devices for measurement of geophysical parameters in bottom area of seas and oceans. Substance: seismic module comprises a tight body (1), inside of which there is a hard disk drive (5), a unit (7) of a hydroacoustic communication channel, a ballast (2) breaker (8), a timer (9) of the breaker (8) of ballast (2), a flashing beacon (10), a joint (11) of external communication, a source of power supply (12), a hydrophysical module (13), a radio beacon (14), a seismic sensor (15), a unit (20) of spatial orientation. Besides, the unit (20) of spatial orientation comprises an electronic 3D compass, three accelerometers and three meters of angular speeds rigidly coupled with the seismic sensor (15). The seismic detector (15) is made in the form of a wideband molecular-electronic sensor. The tight body (1) is made in the form of a hemisphere with a base in the form of a plate, along the upper diameter of which there are mechanical elements of the ballast (2) breaker (8) installed. Mechanical elements of the ballast (2) breaker (8) are made in the form of slings (3), which are coupled to ballast (2) and tightly adjoin the base of the tight body (1) along its lower diameter. The hydroacoustic communication channel for connection of the seismic module with the dispatching station is made as single-relay.

EFFECT: increased validity of recorded data.

3 dwg

FIELD: transport.

SUBSTANCE: invention relates to ship building, particularly, to surface scientific and research vessels. Scientific and research icebreaking vessel is proposed for carrying out 3D seismic technology exploration irrespectively to ice conditions which vessel has a hull where seismic equipment is located, as well as a shaft for bay cable laying. To move source of acoustic waves untethered unmanned submersible is used which bases on a vessel and is dropped and lifted via separate vertical shaft using running - pulling tool.

EFFECT: improved operational performance of scientific and research vessel for seismic exploration.

3 cl, 1 dwg

FIELD: physics; geophysics.

SUBSTANCE: invention relates to geophysics and can be used in marine seismic prospecting. Disclosed is an underwater seismic recording system for reducing noise in seismic signals caused by reflected ghost waves or movement through the water. The system comprises two motion sensors. One sensor has a first response and sensitivity to noise caused by movement of the platform, as well as to acoustic waves. The second sensor has a different structure, which insulates the sensor from acoustic waves such that the response is primarily associated with noise caused by movement. Output data of the responses of the two sensors are combined to eliminate the effect of the noise caused by movement. Upon further combination with a hydrophone signal, noise caused by reflected ghost waves is reduced.

EFFECT: high accuracy of prospecting data.

14 cl, 19 dwg

FIELD: physics.

SUBSTANCE: disclosed is a method for marine seismic survey using one or more marine seismic vibrators. The vibrator sweep function is based on a quality requirement, which may be a final image quality requirement or an environmental requirement. The sweep function may be nonlinear and the energy spectrum may not match the energy spectrum of an airgun.

EFFECT: high accuracy and reliability of survey data.

24 cl, 7 dwg

FIELD: radio engineering, communication.

SUBSTANCE: bottom cable antenna for monitoring offshore seismoacoustic emission, comprising an underwater cable, hydrophone modules connected by the underwater cable through defined distances between each other, surface collection and conversion equipment connected to one end of the underwater cable, is provided with an anchor which is tied to the opposite end of the underwater cable, additional loads tied to the underwater cable between corresponding hydrophone modules and floating suspensions tied to the underwater cable to corresponding hydrophone modules, wherein the hydrophone modules are in the form of pressure inlets. Use of pressure inlets instead of two hydroacoustic antennae significantly reduces the cost of the bottom antenna and simultaneously solves problems associated with the quality of contact between the sensor and the ground by eliminating noise which accompanies said contact. Use of a large number of said sensors solves the problem of picking up waves of different polarisation based on kinematic characteristics thereof.

EFFECT: high noise-immunity by preventing dragging of the antenna on the ground.

1 dwg

FIELD: physics.

SUBSTANCE: disclosed is a method for marine seismic survey using one or more marine seismic vibrators. The vibrator sweep function is based on a quality requirement, which may be a final image quality requirement or an environmental requirement. The sweep function may be nonlinear and the energy spectrum may not match the energy spectrum of an airgun.

EFFECT: high accuracy and reliability of survey data.

24 cl, 7 dwg

FIELD: physics.

SUBSTANCE: disclosed is an induction-dynamic driver for a seismic vibrator, which comprises an induction-dynamic motor which consists of a flat exciting coil and an adjacent electroconductive plate - motor armature, and a semiconductor power supply circuit comprising a double-section capacitive storage with charging devise and switching devices. The drive is characterised by the capability for real-time control of the value and duration of the mechanical pulse generated by the motor armature, as well as the capability to recuperate magnetic field energy of the motor in the capacitive storage.

EFFECT: broader functional capabilities of the device.

2 dwg

FIELD: physics.

SUBSTANCE: non-explosive sources of seismic waves are placed on two pivotally connected platforms. The inclination angle of the platforms relative to each other is set depending on natural or artificial relief non-uniformities in the range of ±45° or, when one of the platforms if fixed horizontal to the earth's surface, the inclination angle of the second platform is varied in the range of ±90°, thereby achieving tight adjoining of the platforms to a selected area on the earth's surface, and the non-explosive sources for exciting seismic wave are turned on with a given interval. The value of the inclination angle of the platforms given based on the condition of the location and the location of the platforms, determined using a GLONASS (GPS) navigation system, are transmitted to receiving stations.

EFFECT: high efficiency of emitting transverse seismic waves.

2 cl, 4 dwg

FIELD: physics; geophysics.

SUBSTANCE: invention relates to geophysics and can be used in land-based seismic survey. The disclosed method for use in land-based seismic survey includes a step of transmitting a plurality of source control commands to a plurality of seismic sources over a VHF/IP network using a UDP without a storage state. Congestion on the VHF/IP network is managed using the UDP while transmitting the source control commands. The invention also discloses a program storage medium encoded with instructions which, when executed by a processor, execute said method and a computer programmed to execute said method of transmitting seismic data.

EFFECT: high throughput and reliability of two-way data transmission.

14 cl, 9 dwg

FIELD: physics.

SUBSTANCE: seismic vibrator has a base plate with at least four isolators isolating a frame from the base plate. Each of these isolators is offset from the contact area of the base plate on shelves of the base plate. An accelerometer mounted directly on the base plate detects the acceleration imparted to the plate. To reduce flexing and bending, the plate has an increased stiffness and approximately the same mass of a plate for a comparably rated vibrator. The accelerometer is mounted at a particular location of the plate that experiences transition between longitudinal flexing along the longitudinal axis of the plate. This transition location better represents the actual acceleration of the plate during vibration and avoids overly increased and decreased acceleration readings that would be obtained from other locations on the plate.

EFFECT: high accuracy of exploration data.

26 cl, 27 dwg

FIELD: physics.

SUBSTANCE: disclosed is a method of exciting seismic waves using an energy converter, having an active part and a reactive part, a drive for cyclic movement of the reactive part and a system for controlling movement of the reactive part. According to the disclosed solution, kinetic energy reserves of the reactive part are created and force action of the active part is applied onto the investigated medium by transferring energy from the reactive part to the active part. Independence of cyclic movement of the reactive part from the active part is structurally provided and the force action of the active part is applied on the investigated medium independent of the cyclic nature of movement of the reactive part.

EFFECT: high seismic efficiency.

1 dwg

FIELD: physics.

SUBSTANCE: disclosed is a system for vibroseismic survey of a geological feature, having at least one vibrator control unit 11 lying near the geological feature, and a control command decoder 7, whose outputs are connected to inputs of at least one vibrator control unit 11. The system also has an analyser connected to an electric power supply unit 1, said analyser being connected by the first, second, third, fourth and fifth data inputs, respectively, to outputs of a storage 2 on a magnetic tape, a display 3, a keyboard unit 4 for inputting control commands, a standard signal generator 8 and the control command decoder, connected by a communication channel to the control command decoder 7. The system has, near the geological feature, a seismic station 9 which is connected by first leads through a matching device 10 to the sixth data input of the analyser unit 1 and by second leads to inputs of the standard signal generator 8.

EFFECT: high accuracy of data of vibroseismic survey of a geological feature.

7 cl, 6 dwg

FIELD: physics.

SUBSTANCE: seismic vibrator has an emitter board 1 with supports 2, a tightening weight 3 and an electromagnet whose inductor 4 is mounted on the tightening weight, and the armature 7 rests on the supports 2 and is separated from the inductor by an air gap 8. The value of the gap exceeds the working stroke of the tightening weight relative the emitter board, thereby facilitating non-impact interaction of the armature and the inductor of the electromagnet. A damper 9 is placed between the tightening weight and the board. The supports are provided with springs which provide elastic pressing of the armature to the supports and prevent its bounce during operation.

EFFECT: low level of noise and seismic interference.

2 dwg

FIELD: physics.

SUBSTANCE: method and system of controlling seismic vibrators during seismic survey involves acquiring real-time field survey locations for a first plurality of seismic vibrators, determining at least one geometrical relationship between each of the first plurality of seismic vibrators as a function of the field survey locations, selecting a second plurality of seismic vibrators from the first plurality of vibrators as a function of the at least one geometrical relationship, selecting source parameters for the second plurality of seismic vibrators as a function of the field survey locations and controlling the second plurality of seismic vibrators to transmit seismic energy into the earth. A third plurality of vibrators is selected based on geometrical relationships and associated source parameters are determined based on vibrator locations. Multiple vibrator groups may acquire data continuously without interruption.

EFFECT: high accuracy and information content of the obtained survey data.

30 cl, 9 dwg

FIELD: physics.

SUBSTANCE: source is made from pipes joined by a sleeve, having two rows of exhaust windows: lower main and upper ignitor windows. The cross-sectional area of the main windows is not smaller than that of the inner hole of the sleeve. In one of the tubes there is a downhole chamber and an ignitor chamber connected to each other through axial orifice holes in a shutter. The shutter is fitted into the sleeve on the neck of a hollow core and closes the main windows. When the main windows are closed, the shutter is pressed by a spring to a thrust shoulder on the core. The cavity of the downhole chamber is closed by a socket at the bottom. The cavity of the ignitor chamber is bounded by the butt-end of the housing at the top. There is a solid piston body inside the sleeve in the top cavity of the hollow core which enters the blind hole in the plunger. The piston body can move back and forth and opens the downhole chamber. Downward movement of the piston in the cavity in the core is restricted by the shoulder and its upward movement is restricted by the top end of the housing. In extreme positions of the piston, radial channels of the core and the plunger are joined and open, and closed in intermediate positions. The cavity over the piston is linked to the cavity underneath through large axial holes. The piston, sleeve and housing are such that their connection is the piston drive. In one of the pipes - the lower pipe - there is a receiver cavity which is closed at the top by a coupling sleeve and by a cover at the bottom. The receiver cavity is connected to the downhole chamber through feed channels, the axial and radial channels in the core and the radial channels in the plunger. In the top part of the source, there is a hydraulic suspension consisting of a slider whose sealing surface is mated with the housing and the tailpiece. The tailpiece is rigidly fixed in the top part of the housing. The cavity in the tailpiece is filled with oil and is linked through radial holes in the tailpiece with the oil cavity in the top part of the housing.

EFFECT: high pulse strength and easier operation.

1 dwg

FIELD: seismic prospecting, applicable for excitation of seismic waves by on unexplosive seismic source with an electromechanical drive.

SUBSTANCE: in the claimed device the main and additional excitation windings are made in the form of excitation windings of direct and reverse motion of the radiator operating member. The device uses a commutating capacitor, which via the first commutating thyristor is connected to the excitation winding of the direct and reverse motion of the operating member, and via the second commutating thyristor - to the excitation winding of the direct and reverse motion of the operating member, the commutating capacitor is shunted by the series-connected third diode and the third inductance coil.

EFFECT: enhanced efficiency and repetition frequency of force actions, simplified control of the amplitude and duration of the excited seismic waves.

3 dwg

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