RU2536837C1 - Method for parametric reception of hydrophysical and geophysical waves in marine environment - Google Patents

Abstract

FIELD: physics, hydrophysics.

SUBSTANCE: method for parametric reception of hydrophysical and geophysical waves in a marine environment is characterised by that, in addition to scanning the environment with low frequency hydroacoustic signals, it also includes infra-low frequency pumping of the sea bottom along the direction of parametric antennae which radiate from the centre of the investigated water area; furthermore, a receiving hydroacoustic transducer is formed from two vertically spaced apart receivers, mounted on a mobile carrier which moves on the boundary of the investigated water area, wherein the low frequency hydroacoustic signals are generated by two vertically spaced apart forward-scattering parametric antennae, wherein during movement on the perimeter of the water body, the direction of the maximum manifestation of the measured information waves is determined; further, the receiving unit is moved in the said directions towards the location of the radiating transducers with a constant velocity minimally possible for the carrier or with given stoppage intervals, wherein the method also includes measuring and specifying the location of sources of the maximum manifestation of information waves, the length thereof and space-time characteristics thereof, and based thereon, identifying the measured waves, identification thereof as water hydrophysical or bottom geophysical, e.g., hydrocarbon or seismic ones; furthermore, upon detecting geophysical waves and selection of spectral characteristics thereof, the latter are compared with generalised reference spectra and the identity of the measured information waves to specific types of hydrocarbon accumulations is determined or are identified as earthquake precursors.

EFFECT: invention reduces the time and equipment costs on investigating a water area with search purposes for hydrocarbon deposits and enabling detection of seismic disturbances of the medium of earthquake precursors.

7 cl, 10 dwg

Description

The method relates to hydrophysics, geophysics and can be used to solve the problems of long-range parametric reception of waves of various physical nature (acoustic, electromagnetic, hydrodynamic) in the marine environment formed by natural and artificial sources of the aquatic environment and the seabed (marine objects, hydrodynamic and seismic processes, as well as hydrocarbon deposits) in the frequency range of tens-units-fractions of Hertz.

Currently, the problem of creating an effective method for the search for oil deposits on the sea shelf is becoming increasingly acute all over the world. This is due to the limited proven reserves of oil on land, which, according to experts, should be enough only for the next 20-30 years. In this regard, the question of developing a fast and high-precision method for detecting oil and gas deposits near the bottom of the sea shelf is becoming relevant. At the same time, it is also relevant and close in technical essence to solving the problem of effective (proactive) wave reception - the harbingers of strong earthquakes.

It is known that the presence of oil deposits on the shelf is usually characterized by the infiltration of petroleum hydrocarbons and gases into the bottom layers of the water. The presence of such emissions is most characteristic of gas deposits, while petroleum hydrocarbons due to the low diffusion rate in sea water are characterized by an almost complete lack of solubility in it and rapid neutralization, and due to the processes of chemical and biochemical interaction with the components of sea water, they are almost completely localized near places oil infiltration to the surface of the seabed and further into the marine environment.

There is a method of parametric reception of waves of various physical nature in the marine environment, including the formation in it of a zone of nonlinear interaction and parametric transformation of elastic pump waves with measured information waves (see RU No. 2158029). The method implements the laws of nonlinear acoustics, but cannot be used as a prototype of the claimed invention. The disadvantages of the considered technical solution, limiting the possibility of its implementation in the direct mobile search for offshore hydrocarbon deposits, is the low sensitivity and noise immunity of the reception of waves generated by the deposits, and, as a result, the limited (hundreds of meters-units kilometers) range of the parametric reception of information signals of various physical nature in the infrasound and fractional (units-parts of Hertz) frequency ranges. These disadvantages are due to the low effect of nonlinear conversion of interacting waves in the working area of the marine environment, as well as the presence of intense environmental interference in the infrasound and fractional frequency ranges corresponding to the emissions of hydrocarbon deposits. In addition, when searching for hydrocarbon deposits, intense man-made radiation generated by the engineering structures of the surveyed water area is added to environmental noise. As a result of this, the possibility of far parametric reception of geophysical waves generated by hydrocarbon deposits and harbingers of earthquakes in the seabed is not realized, as well as the possibility of mobile search and determination of their sources in the waters of the sea shelf.

These disadvantages are associated with the characteristics of the nonlinearity of the marine environment, which is as follows. It is known that the so-called non-linear parameter of water E, which, as a rule, is insignificant, makes the main contribution to the efficiency of converting a high-frequency signal to low-frequency harmonics. For example, for distilled water, E = 3.1 at a temperature of 0 ° C; 3.5 - at 20 ° C; 3.7 - at 40 ° C. For sea water at a salinity of 35% in the temperature range of 20-30 ° C, the value of E is 3.6. Experimental work carried out in the open sea showed that the coefficient of nonlinearity E in a wide frequency range to depths of 300 m varies slightly and does not exceed 4. Therefore, it is impossible to expect fundamentally new effects compared to those already studied in the open ocean at arbitrary depths; solutions, for example, patterns of nonlinear acoustics.

There is also known a method for the parametric reception of hydrophysical and geophysical waves in the marine environment, including sounding the medium with low-frequency hydroacoustic signals with the formation of two spatially spaced at the receiving point of the luminal parametric antennas as zones of nonlinear interaction and parametric transformation of the luminous and measured information waves, the subsequent two-channel reception of parametrically transformed luminal signals and their processing with restoration of their original hara characteristics of the measured information waves (see RU No. 2452041). The specified method implements the laws of translucent sonar hydrophysical and geophysical fields in the marine environment as a parametric with low-frequency illumination (pumping) of the controlled environment.

The disadvantage of this technical solution is the lack of efficiency in the study of bottom massifs (revealing the structure of bottom sediments and searching for hydrocarbon deposits of various types in them), as well as the often impossibility of reliable perception of seismic disturbances of the environment - precursors of earthquakes.

EFFECT: achievement of long-range noise-tolerant detection (reception) in the marine environment and measurement of the spatio-temporal and spectral structure of the fields of hydrophysical and geophysical waves generated by marine objects and bottom hydrocarbon deposits, as well as seismic disturbances of the medium by earthquake precursors in the infrasonic and fractional frequency ranges over an extended offshore (provides long-range noise-tolerance reception of the generated information waves of "small amplitudes" in the frequency range d syatki unit-share Hertz). It also reduces the time and money spent on the survey of water for search purposes, which is realized by direct mobile search for their sources in the parametric mode of translucent sonar.

To solve this problem, a method for the parametric reception of hydrophysical and geophysical waves in the marine environment, including sounding the medium with low-frequency hydroacoustic signals with the formation of two spatially spaced at the receiving point of the luminal parametric antennas as zones of nonlinear interaction and parametric transformation of the luminal and measured information waves, followed by two-channel reception parametrically transformed luminal signals and their processing with restoration by the initial characteristics of the measured information waves, it differs in that in addition to sounding the medium with low-frequency sonar signals, an infra-low-frequency pumping of the seabed soil is carried out along the direction of the parametric antennas, while the low-frequency and infra-low-frequency sonar signals are emitted from the center of the investigated water area, in addition, the receiving sonar transducer is formed from two vertically spaced receivers are placed on a mobile carrier, which they move along the boundary of the surveyed water area, and two vertically spaced luminous parametric antennas are formed by low-frequency hydroacoustic signals, and the infrared-low-frequency radiating transducer generates pumping of sea soil along a controlled path and amplifies the level of seismic background waves, while during movement along the perimeter of the water area, the directions of the maximum manifestation of the measured information waves, then, in these directions, the receiving unit is moved to the location I of emitting transducers, and the receiving unit during the search operations is moved at a constant speed as fast as possible for the carrier or at specified intervals of stops, while the locations of the sources of the maximum manifestation of information waves, their length and the characteristics of the spatio-temporal dynamics are measured and specified identification of the measured waves, their affiliation with water hydrophysical or bottom geophysical, for example hydrocarbon or seismic, in addition, when aruzhenii geophysical waves and allocation of their spectral characteristics compared to the last generalized reference spectra and the measured detected accessory information waves to specific types of hydrocarbon accumulations or identified as precursors of earthquakes. In addition, the sounding of the medium by low-frequency sonar signals is carried out by means of a low-frequency radiating sonar transducer, which is located in an aqueous medium. In addition, the processing of parametrically transformed luminal signals includes their amplification in the conversion band, transfer of their time-frequency scale to the high-frequency region, measurement of the phase difference of the signals from the receiving antennas and their subsequent narrow-band spectral analysis, separation of the parametric components of the total and difference frequency of the luminal and information signals . In addition, the infra-low-frequency pumping of the soil of the seabed is carried out by the infra-low-frequency emitter, which is located on the seabed. In addition, low-frequency waves of pumping an aqueous medium emit in the frequency range of tens to hundreds of Hertz. In addition, infralow-frequency waves of pumping the soil of the seabed form in the frequency range of a unit-fraction of Hertz. In addition, the reception and measurement of the characteristics of hydrophysical and geophysical waves is carried out in the mode of minimum speed for the carrier or with specified intervals of stops, providing stable reception and separation of information signals.

A comparative analysis of the features of the claimed and well-known technical solutions indicates its compliance with the criterion of "novelty."

The features of the characterizing part of the claims solve the following functional tasks.

The signs “in addition to sounding the medium with low-frequency hydroacoustic signals, carry out infralow-frequency pumping of the seabed soil” provides the possibility of forming zones of nonlinear interaction and parametric transformation of the luminal and measured information waves (which are the result of pumping the sea soil by its infra-low-frequency processing along a controlled path, as well as seismic waves of earthquake precursors spreading in the sea soil and out into the water do on a controlled track.

Signs indicating that the infra-low-frequency pumping of the seabed soil is carried out “along the direction of the parametric antennas”, increase the efficiency of the “work” of non-linear interaction zones and the parametric conversion of the lumen and measured information waves, which helps to increase the reliability and reliability of the measured results.

Signs indicating that “low-frequency and infra-low-frequency sonar signals are emitted from the center of the surveyed water area”, together with signs indicating that “the receiving sonar transducer is formed from two vertically spaced receivers, placed on a mobile carrier that is moved along the boundary of the surveyed water area”, provide the ability to identify the profile (trajectory of the carrier vessel) of the most promising for the survey trajectory to identify search recognition kov (after completing the bypass of the perimeter of the prospected area of the water area).

Signs indicating that "two vertically spaced luminous parametric antennas are formed by low-frequency hydroacoustic signals", provides the possibility of effective noise-tolerant reception and separation of measured information waves by the phase-reception method and the subsequent processing of parametrically transformed luminous signals. At the same time, the spacing of the receiving converters forming parametric antennas, in accordance with the correlation properties of the luminal signals in the vertical plane (not more than ten wavelengths of the luminal signals), provides noise-resistant reception of the luminal signals and the subsequent isolation of the signs of information fields from them (see Williams RE, Wei CH The Correlation of Acoustic Wavefront and Signal Time-Base Instabilities in the Ocean, J. Acoust. Soc. Amer., 59, 1310-1316, 1976).

Signs indicating that "the infrared-low-frequency radiating transducer forms the pumping of sea soil along a controlled path and enhances the level of seismic background waves" provide the possibility of direct mobile search for geophysical waves generated by hydrocarbon deposits pumped by infra-low-frequency radiation due to the enhancement of nonlinear interaction processes and parametric transformation of and measured information waves.

Signs indicating that “in this case, during the movement along the perimeter of the water area, the directions of the maximum manifestation of the measured information waves are fixed”, they minimize the number of search passes in the water area by identifying a limited number of profiles that are most promising for detailed exploration.

Signs indicating that in the recorded directions of the maximum manifestation of the measured information waves "the receiving unit is moved to the location of the emitting transducers", provide the opportunity to receive measuring signals on the most promising profile.

Signs indicating that the carrier with the receiving unit "during the search operations move at a constant minimum speed possible for the carrier or at specified intervals of stops" provide reliable reception of information waves by the mobile receiving system.

The signs “measure and clarify the locations of the sources of the maximum manifestation of information waves, their length and characteristics of spatio-temporal dynamics, and they identify the measured waves, their belonging to water hydrophysical or bottom geophysical, such as hydrocarbon or seismic” provide the ability to identify the measured waves, their belonging to aquatic hydrophysical or bottom geophysical, formed by hydrocarbon or seismic sources, providing t reliable identification information wave sources and use these parameters as search features.

The sign “when detecting geophysical waves and isolating their spectral characteristics, the latter are compared with generalized reference spectra and the belonging of the measured information waves to specific types of hydrocarbon accumulations or identified as precursors of earthquakes” ensures the completion of operations (measuring technologies) of the proposed method of mobile search (detection) of sources information waves on the sea shelf and their systematization according to the types of deposits.

An additional distinguishing feature “sounding of the medium with low-frequency sonar signals is carried out by means of a low-frequency radiating sonar transducer, which is located in the aquatic environment” ensures the effective formation of a double parametric antenna.

An additional distinguishing feature is the “processing of parametrically transformed luminal signals, including their amplification in the conversion band, transfer of their time-frequency scale to the high-frequency region, measurement of the phase difference of the signals from the receiving antennas and their subsequent narrow-band spectral analysis, separation of the parametric components of the total and difference frequency of the luminal and information Signals ”provides reliable restoration of the initial information signal.

An additional distinguishing feature is the “infralow-frequency pumping of the seabed soil carried out by the infralow-frequency emitter, which is located on the seafloor” ensures efficient pumping of the seafloor array and increases the informational value of exploration work. ”

An additional distinguishing feature is “low-frequency waves of pumping of an aqueous medium emit in the frequency range of tens to hundreds of Hertz” provides the possibility of long-range parametric reception of geophysical and hydrophysical waves in extended sea areas.

An additional distinguishing feature “infra-low-frequency waves pumping the seabed soil into the frequency range of a unit-fraction of Hertz” provides the possibility of efficient parametric reception of geophysical waves generated by hydrocarbon deposits due to additional pumping of the soil by infra-low-frequency waves close to the resonant radiation of deposits or seismic waves of earthquake precursors.

An additional distinguishing feature “reception and measurement of the characteristics of hydrophysical and geophysical waves is carried out in the mode of minimum speed for the carrier or with predetermined intervals of stops providing stable reception and extraction of information signals” ensures reliable reception of information waves by eliminating the interference caused by the mobile monitoring system.

Thus, the totality and interconnection of the considered distinguishing features of the proposed method provides the possibility of obtaining a common technical effect, namely, the achievement of early detection (reception) in the marine environment and the measurement of the spatio-temporal and spectral structure of the fields of hydrophysical and geophysical waves generated by marine objects and bottom hydrocarbon deposits , as well as seismic disturbances of earthquake precursors in the infrasound and fractional ranges on an extended sea that is realized by direct mobile acoustic search for their sources, as well as due to the additional pumping of sea soil and the amplification of its seismic background formed by the field of earthquake precursors.

The invention is illustrated by drawings. Figure 1 shows the structural diagram of a measuring monitoring system that implements the method of long-range parametric reception in the marine environment and measuring the characteristics of geophysical and hydrophysical fields of sources of the aquatic environment and the seabed. Figure 2 presents a diagram of the survey of the water area, measuring the characteristics of the fields and determining the location of seismic sources of information waves. Figure 3-5 shows the spectra and spectrograms of the hydrophysical fields of the sources of marine waters, which correspond to measurements of phase difference signals of horizontally spaced receiving elements. In this case, Fig.3 is a spectrum of acoustic resonant and hydrodynamic fields of a moving marine vessel, measured in a parametric manner. The frequency of illumination of the medium is 400 Hz, the length of the surveyed water area is 30 km, the horizontal spacing of the receiving elements of the bottom antenna is 200 m. Figure 4 is a spectrum of the electromagnetic radiation of a marine vessel, measured by the parametric translucent method, the frequency is about 390 Hz. The length of the surveyed water area is 45 km, the horizontal separation of the receiving elements of the bottom antenna is 200 m. The spectrum represents the result of a nonlinear interaction of acoustic and electromagnetic waves in a conducting marine environment. 5 is a spectrum of noise emission of a marine vessel (shaft-lobe scale). The result of the “triple” nonlinear interaction of waves of various physical nature in the marine environment is presented. Acoustic waves are observed at a frequency of illumination of the medium of 386 Hz, electromagnetic waves at a frequency of 400 Hz and acoustic waves of a shaft-blade scale of a marine vessel. Figure 6-8 shows the generalized (used as reference) spectra of geophysical waves of the seabed formed by hydrocarbon (hereinafter HC) deposits at various degrees of their saturation with gas and oil. Figure 6 - spectrum of hydrocarbon deposits (corresponds mainly to gas accumulations). Fig.7 is a spectrum of hydrocarbon deposits (corresponds mainly to gas condensate accumulations). Fig - spectrum hydrocarbon deposits (corresponds mainly to deposits with gas inflow). Fig.9 - recording earthquake signals (amplitude-time characteristics). Figure 10 - records of earthquake precursors presented in 3D.

The measuring technology of the patterns of energy storage of the seismic background and its subsequent re-emission of hydrocarbons by the microseismic waves of the Earth consist in using the “listening” method. This method is similar to medical listening to a living organism, in which similar waves are formed due to the work of the heart. In hydrocarbon deposits, such as extended cavities, such waves are formed due to the presence of microseismic and other similar vibrations in the earth's environment. Moreover, depending on the spatial dimensions and density of deposits, such as seashells, the formation and reradiation of waves close to resonance occurs in the frequency range of a fraction of a few tens of hertz. In some cases, re-emission covers the frequency range up to 200 Hz. The radiation of the deposits, as practice shows, is tapped and recorded on the surface of the earth using special traps (antenna hemispheres), then the measurements are further processed and analyzed. In this case, the surface of the earth acts as a horn amplifying noise signals. But, as practice shows, not everything that effectively makes noise is an oil reservoir, in this case, a special identification of the received noise is necessary, the essence of which is used in the claimed invention. The patterns of formation and practical use of microseismic emissions of the Earth are intensively investigated and widely used in the practice of searching for hydrocarbon deposits in marine conditions (for example, see Biryaltsev E.V., Ryzhov V.A., Shabalin N.Ya. // Information reception and processing in complex systems. - Kazan: Kazan University Publishing House. 2005. - Issue 22. - S.113-120).

The theoretical justification of the laws of nonlinear acoustics and their implementation in the proposed parametric method for searching and measuring the characteristics of geophysical and hydrophysical waves in a conducting marine environment is as follows. It is known that the characteristics of hydrophysical fields of the marine environment of various physical nature in which the hydroacoustic wave propagates affect its parameters (see Voronin V.A., Kirichenko I.A. Study of a parametric antenna in a stratified medium with a variable sound velocity field. Journal “ University Proceedings. ”- Electromechanics, No. 4, 1995). This is due to the fact that the influence of hydrophysical fields is carried out through a change in the density and coefficient of elasticity of the medium. According to its physical nature, the inventive method provides for a change in the density and (or) temperature of a controlled aqueous medium, the distribution of these values in an extended working area of parametric reception (interaction of waves of various physical nature), which is a consequence of the impact on the marine environment with measured information fields generated by a complex of information signals propagating in the surveyed water area. Obviously, all infra-low-frequency waves generated by special marine sources or natural disasters (for example, earthquakes or tsunamis) will be reliably recorded.

Qualitative and quantitative characteristics of the process of interaction of elastic (acoustic) and electromagnetic waves in conductive media are as follows. When an electromagnetic wave is emitted into a marine electrically conductive medium, its absorption and attenuation occur. At the same time, its length is significantly reduced. Depending on the conductivity of the marine environment, the distance at which the electromagnetic wave of infra-low frequencies decays (from units of Hz to hundreds of Hz) can range from 10-20 meters to 100-200 meters. In this case, the "length" of the damped electromagnetic wave can be from 0.1-0.2 to 10-20 meters.

Mathematically, the process of propagation of an electromagnetic wave is described by the well-known diffusion equation, which is derived on the basis of the theory of the interaction of an electromagnetic wave in a conducting fluid, which approximately describes the marine environment. The theoretical basis of the pattern under consideration is that the electric currents generated by the electromagnetic wave pass into Joule heat. Dissipative losses on the conduction current in the marine environment are converted into heat losses, which in turn change the mechanical characteristics of the conductive fluid (density, temperature, heat capacity, etc.). When an acoustic pump wave is transmitted through such a spatially modulated nonlinear medium, its parameters will be modulated by changing the phase velocity of the wave along the propagation path. The spectrum of an elastic (acoustic) pump wave changes due to nonlinear conversion, and high-frequency and low-frequency parametric components are formed in it. The parametric reception of information waves in the system under consideration is manifested as amplitude-phase modulation of the acoustic pump wave, which propagates with it to the receiving point and then is allocated in the signal processing path. The process of generating parametric wave reception by a transverse hydroacoustic line can be explained by the usual system of hydrodynamic equations for a viscous fluid when superimposed on the equation of state of the corresponding changes in the phase velocity of sound in time and space.

To calculate the propagation velocity of an elastic (acoustic) wave, one can apply the well-known formula

, $${\text{C}}_{\left(\text{t}\right)}=\sqrt{{\text{1 / P}}_{\text{o}}{\text{β}}_{\text{s}\left(\text{t}\right)}}$$

,

- коэффициент адиабатической сжимаемости жидкости; υ - удельный объем.Where $${\text{β}}_{\text{s}}=-\text{1 / υ}{\left(\raisebox{1ex}{$\partial \text{υ}$}\!\left/ \!\raisebox{-1ex}{$\partial \text{P}$}\right.\right)}_{\text{s}}$$

- coefficient of adiabatic compressibility of the liquid; υ is the specific volume.

Using the relation between adiabatic and isothermal compressibility β _S = Gυ / G _p β _t we can obtain the following expression for the phase velocity

$${\text{C}}_{\left(\text{t}\right)}=\sqrt{\left({\text{C}}_{\text{p}}{\text{/ C}}_{\text{υ}}\right){\left(\partial \text{P /}\partial \text{ρ}\right)}_{\text{t}}}$$

Obviously, qualitatively any changes in density ρ, pressure P at a constant temperature lead to a change in the phase velocity of sound in time in the zone of interaction of an electromagnetic wave with an elastic wave through a marine medium conducting electric current. That is, in contrast to the classical equations of hydrodynamics for an ideal fluid, which are used in the theory of nonlinear parametric radiators, in the latter equations the phase velocity of an elastic wave changes in time and space according to the law of change of the electromagnetic wave. Thus, if an electromagnetic wave of harmonic frequency Ω _em propagates in the working zone of the lumen parametric system, then the phase velocity of the elastic (lumen acoustic) wave C _(t) will also change with the same frequency Ω _sv = Ω _em . Quantitative characteristics of the modulation depth can be obtained using specific engineering models for implementing the method.

Theoretical and marine experimental studies substantiate the regularity and effectiveness of the so-called triple interaction of acoustic translucent waves with the acoustic and electromagnetic fields of marine sources. It is shown that marine sources, for example, seismic disturbances of the seabed, can be detected by signs of their transformation by elastic and electromagnetic fields of transparent acoustic waves propagating in the medium. The analytical form of such a transformation is presented in the following form (see Shostak S.V., Mironenko M.V., Surgaev I.N. Amplitude-phase modulation of translucent acoustic waves during their interaction with electromagnetic waves in the marine environment // Collection of articles. - Vladivostok. TOVMI. Issue 22, 2001, p. 82-88):

, $$\begin{array}{l}{\text{P}}^{\text{*}}\left(\text{t}\right)={\text{0.5P}}^{\text{2}}\{{\text{J}}_{\text{0}}\left({\text{m}}_{\text{p}}\right)\text{cos}{\text{2ω}}_{\text{one}}\text{t}+{\text{J}}_{\text{one}}\left({\text{m}}_{\text{p}}\right)\left[\text{cos}\left({\text{2ω}}_{\text{one}}-\text{Ω}\right)\text{t}-\text{cos}\left({\text{2ω}}_{\text{one}}+\text{Ω}\right)\text{t}\right]+\\ +{\text{J}}_{\text{2}}\left(\frac{\text{2A}}{\text{P}}\right)\left[\text{cos}\left({\text{2ω}}_{\text{one}}-\text{2Ω}\right)\text{t}+\text{cos}\left({\text{2ω}}_{\text{one}}+\text{2Ω}\right)\text{t}\right]+{\text{J}}_{\text{3}}\left(\frac{\text{2A}}{\text{P}}\right)[\text{cos}\left({\text{2ω}}_{\text{one}}-\text{3Ω}\right)\text{t}-\\ -\text{cos}\left({\text{2ω}}_{\text{one}}+\text{3Ω}\right)\text{t}]+...\}\end{array}$$

,

where P ^* (t), P (t) is the resulting (modulated) and instantaneous values of the translucent acoustic wave; ω ₁ , ω ₂ - the circular frequency of the acoustic translucent and electromagnetic object waves; Ω is the low-frequency acoustic wave from the object; φ is the initial phase of the translucent wave; t is the current time; J _n - n-th order Bessel functions; A ₀ , A _m are the amplitudes of the initial and modulated waves; m is the modulation coefficient. An analysis of this expression shows that the vibrational spectrum of interacting waves consists of an infinite number of components located symmetrically with respect to the doubled central frequency 2ω (equal to ω ₁ + ω ₂ ), the frequency values of which differ from 2ω by n · Ω, where n is any integer. The amplitudes of the n-th side components will be determined by the expression

J _n (2A _m / P) · 0.5P ² .

It follows from this that the contribution of various lateral components to the total power of the modulated oscillation is determined by the value 2A _m / P. Moreover, for small values of the modulation coefficient m _p, the vibrational spectrum consists approximately of harmonics of the center frequency 2ω (total) and two side frequencies: the upper (2ω + Ω) and lower (2ω-Ω).

The drawings show the path for generating the pump signals 1, the underwater emitter 2 of the transparent signals for pumping the aquatic environment, the underwater emitter 3 of the pump signals of the sea soil, a source of hydrophysical waves 4, receiving units 5 and 6, a stabilized frequency generator 7, thyristor inverter 8, matching unit 9 output with underwater cables, stabilized frequency generator 10, thyristor inverter 11, matching unit 12 of its output with underwater cables, path 13 for receiving, extracting and recording information waves, two-channel Iroband amplifier 14, phase difference measuring unit 15, time scale converter of parametrically transformed translucent waves to high-frequency region 16, narrow-band spectrum analyzer 17, recorder 18 (or other storage medium), source of geophysical waves - for example, hydrocarbon deposits, parametric antennas 20, zone of "triple" nonlinear interaction of waves 21, sea bottom 22, sea surface 23, additional infra-low-frequency radiation (pumping) 24 of the sea bottom 22, seismic waves of earthquake precursors 25, water area 26, carrier ship 27.

The structural diagram of a parametric system for measuring the characteristics of hydrophysical and geophysical fields in extended sea areas that implements the proposed method is shown in figure 1. The system includes a path for generating signals of low-frequency and infra-low frequency pumping of the aquatic environment and sea soil 1, connected to underwater emitters of translucent pumping signals 2 and signals of low-frequency pumping of sea soil 3. The measuring system for monitoring the fields of the medium also includes a path for receiving, extracting and recording information waves 13, inputs which are connected to the receiving units 5 and 6, vertically spaced parametric antennas 20.

The path to the formation and amplification of the backlight signals of the medium and the pumping of the sea soil 1 is a two-channel electronic circuit containing serially connected: stabilized frequency generators 7 and 10; thyristor inverters 8 and 11; matching blocks 9 and 12 of their outputs with submarine cables and further with radiating blocks 2 and 3 (see figure 1).

The receiving path of the measuring system 13 (Fig. 1) is an electronic system including a two-channel broadband amplifier 14 connected in series, the inputs of which are connected via the underwater cables to the receiving units of the vertical parametric antennas 5 and 6, and the outputs are with the phase difference measuring unit 15, the output of which connected to a time scale converter of parametrically transformed translucent waves to the high-frequency region 16, then to a narrow-band spectrum analyzer 17, the output of which is connected with a recorder or other carrier of the allocated spectra of information waves 18. In addition, the drawings (Fig. 1) show the source of the formation of hydrophysical waves 4, the working area of nonlinear interaction and parametric conversion of the luminal and information waves (low-frequency luminous parametric antennas) 20, the source of the formation of geophysical waves of hydrocarbon deposits of the seabed 19, sea surface 23, as well as the zone of “triple” nonlinear interaction of waves 21 (low-frequency translucent, acoustic or hydrodynamic and electromagnetic geophysical received due to additional infra-low-frequency pumping of the seabed), as well as waves formed by hydrocarbon accumulations 19.

The claimed method is implemented as follows. Emitters of illumination of the medium and pumping of sea soil 2 and 3, as well as receiving units 5 and 6 are placed (deepened and installed) in relation to the sources of information waves of the surveyed water area so that the areas of their nonlinear interaction are most effectively formed and used. The process of detecting information waves begins with a constant minimum possible movement of the formed luminal parametric antennas for the carrier over the area of the investigated water area ("circulation" relative to the location of the emitting blocks). When signs of information waves are detected, the carrier of the receiving units is moved toward approach, and then removed from the emitting transducers (from the center of the water area) and the locations and length of the sources of information waves are specified. In the discovered places determine their coordinates. By deviating the carrier vessel of the receivers from the straight course, they are moved from the originally traveled line (for example, moved along the snake) and the width of the hydrocarbon pool is determined. In this case, observations and measurements of the spatio-temporal characteristics and dynamics of the waves are made. Next, the carrier vessel of the receiving units returns to the starting point of the perimeter of the surveyed water area, from which the process of detecting and searching for sources of information waves continues (is repeated) around the entire perimeter.

The pattern of measurement of hydrophysical and geophysical waves using the parametric translucent method in the search engine is implemented as follows. The influence of sources of information waves 4, 19, 25 leads to a change in the mechanistic characteristics of the marine environment (density and temperature, which modulate the luminous signals of the illumination of the environment). When an acoustic pump wave is transmitted through such a nonlinear elastic medium modulated in space, its parameters will be modulated by changing the phase velocity along the propagation path. The harmonics arising as a result of the nonlinear interaction of the waves manifest themselves as modulation components of the amplitude and phase of the low-frequency pump waves. Being an inextricably linked component of the low-frequency translucent wave, they are transported over long distances and then are allocated (detected) in the processing units of the receiving path of the field monitoring system and search for their sources.

Strengthening the nonlinear interaction of geophysical waves of the seabed sources, as well as the effectiveness of long-distance reception and subsequent identification of the measured geophysical and hydrophysical waves and determining their location is ensured by additional irradiation of the seabed soil with infra-low-frequency signals, which ensures the total nonlinear interaction of waves (translucent in the direction of the path with additional propagating from the seabed, as well as information) propagating in the sea de.

The increased effect of nonlinear interaction and parametric wave transformation is achieved through the use of the interaction of waves commensurate with the length of the medium of the spatial working zone (extended volume) of the waves, as well as additional irradiation of the seabed. The use in the receiving and processing path of conversion (transfer) operations of the time-frequency scale of pump waves to the high-frequency region ensures the efficient separation of waves of the infra-low-frequency and fractional frequency ranges by existing methods and means of narrow-band spectral analysis and their subsequent registration on carriers.

Figure 1-8 shows the specific results of the implementation of the claimed method (the results of observations and measurements of noise emission from hydrocarbon deposits) obtained in real water areas, which can be used as signs of the manifestation (presence) of subsea hydrocarbon deposits.

Gas reservoir (Fig.6) is characterized by the following features. The spectrogram shows continuous and discrete noises with levels of excess above the background of 10% and 45%, respectively. The discrete row is an asymmetric bell, consisting of three double and two (wider) single components located in the frequency range of about 3.4-4.2 Hz, and its maximum at a frequency of about 3.8 Hz.

Gas condensate reservoir (Fig.7). In the frequency range of about 1.8-4.8 Hz, the spectral power of the intrinsic noise emissions of the hydrocarbon pool reduced to the background is approximately 5% higher than the background. Moreover, in the frequency range from 2.0 to 3.4 Hz over continuous noise, a “letter E lying on the back" is registered, which has two wide (0.2 Hz each) discrete components within 25% higher than continuous noise and 30% exceeding background. The central line as a double discrete component exceeds solid noise by about 15% and exceeds background by 20%. In the frequency range from 3.5 Hz to 5 Hz, a “rugged meander” (a series of three cut rectangles) is recorded, in which the meander level exceeds the continuous noise by about 15% and background by 20%.

Deposit with gas influx (Fig. 8). In the frequency range from 1.0 Hz to 7.0 Hz, the spectral power of the intrinsic noise emissions of the hydrocarbon deposit reduced to the background is approximately 10–20% higher than the background level. Moreover, in the frequency range from 2.0 to 5.5 Hz, an equilateral “triangle” with a peak (maximum spectral density) is recorded at a frequency of about 4.0 Hz, which exceeds the background level by about 40%.

Thus, the technical solutions of the proposed method for the long-range parametric reception and measurement of the characteristics of geophysical and hydrophysical waves of low-frequency, infra-low-frequency and fractional ranges have implemented practical ways to build and operate a large-scale hydro-acoustic system for integrated monitoring of hydrophysical and geophysical fields in the infra-low and fractional ranges formed by sources of the aquatic environment and the marine environment bottom. The length of the system under consideration (a large scale of the range of parametric wave reception) is provided by the sounding (pumping) of the medium by weakly damped low-frequency acoustic signals in the range of tens to hundreds of Hertz. The provision in the inventive method of early detection and location of sources of geophysical and hydrophysical waves generated by hydrocarbon deposits, as well as precursors of earthquakes, is achieved through measuring technologies of translucent sonar and the implementation of the laws of nonlinear interaction of waves of various physical nature in it, which is theoretically justified and confirmed by marine experiments.

The detection and identification of geophysical waves, as well as their belonging to the characteristic hydrocarbon deposits, is carried out on the basis of generalized spectral characteristics and their spatio-temporal dynamics, which are obtained at the sites of existing oil producing wells.

Claims (7)

1. The method of parametric reception of hydrophysical and geophysical waves in the marine environment, including sounding the medium with low-frequency hydroacoustic signals with the formation of two spatially spaced at the receiving point of the luminal parametric antennas as zones of nonlinear interaction and parametric transformation of the luminal and measured information waves, followed by two-channel reception of parametrically transformed luminal signals and their processing with restoration of the initial characteristics measured information waves, characterized in that in addition to sounding the medium with low-frequency hydroacoustic signals, an infra-low-frequency pumping of the seabed soil is carried out along the direction of the parametric antennas, while the low-frequency and infra-low-frequency hydroacoustic signals are emitted from the center of the investigated water area, in addition, the receiving hydroacoustic transducer is formed from two vertically receivers are placed on a movable medium, which is moved along the border of the survey In this case, two vertically spaced luminous parametric antennas are formed by low-frequency hydroacoustic signals, and the infrared-low-frequency radiating transducer generates pumping of sea soil along a controlled path and increases the level of seismic background waves, while during movement along the perimeter of the water area, the directions of the maximum manifestation of the measured information waves are recorded, further, in these directions, the receiving unit is moved to the location of the emitting transducers d, and the receiving unit during the search operations is moved at a constant speed as fast as possible for the carrier or at specified intervals of stops, while the locations of the sources of maximum manifestation of information waves, their length and the characteristics of the spatio-temporal dynamics are measured and specified, and the measured waves, their belonging to hydrophysical or bottom geophysical waves, for example hydrocarbon or seismic waves, in addition, when detecting geophysical waves and the allocation of their spectral characteristics, the latter are compared with generalized reference spectra and the belonging of the measured information waves to specific types of hydrocarbon accumulations is identified or identified as earthquake precursors. 2. The method according to claim 1, characterized in that the sounding of the medium with low-frequency sonar signals is carried out by means of a low-frequency radiating sonar transducer, which is located in an aqueous medium. 3. The method according to claim 1, characterized in that the processing of the parametrically converted luminal signals includes their amplification in the conversion band, transferring their time-frequency scale to the high-frequency region, measuring the phase difference of the signals from the receiving antennas and their subsequent narrow-band spectral analysis, highlighting the parametric components of the total and difference frequency of the luminal and information signals. 4. The method according to claim 1, characterized in that the infra-low-frequency pumping of the soil of the seabed is carried out by an infra-low-frequency emitter, which is located on the seabed. 5. The method according to claim 1, characterized in that the low-frequency waves of pumping the aqueous medium emit in the frequency range of tens to hundreds of Hertz. 6. The method according to claim 1, characterized in that the infra-low-frequency waves pumping the soil of the seabed form in the frequency range of a unit-fraction of Hertz. 7. The method according to claim 1, characterized in that the reception and measurement of the characteristics of hydrophysical and geophysical waves is carried out in the mode of minimum speed for the carrier or at specified intervals of stops, providing stable reception and selection of information signals.

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