Development of hydraulic low frequency marine seismic vibrator

Low-frequency seismic data are crucial for convergence of full-waveform inversion (FWI) to reliable subsurface properties. However, it is challenging to acquire field data with an appropriate signal-to-noise ratio in the low-frequency part of the spectrum. We have extrapolated low-frequency data from the respective higher frequency components of the seismic wavefield by using deep learning. Through wavenumber analysis, we find that extrapolation per shot gather has broader applicability than per-trace extrapolation. We numerically simulate marine seismic surveys for random subsurface models and train a deep convolutional neural network to derive a mapping between high and low frequencies. The trained network is then tested on sections from the BP and SEAM Phase I benchmark models. Our results indicate that we are able to recover 0.25 Hz data from the 2 to 4.5 Hz frequencies. We also determine that the extrapolated data are accurate enough for FWI application.

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Local‐trace zeroing and spike zeroing: Two short automated noise‐rejection routines to remove noise and spikes on seismic traces

Geophysics ◽

10.1190/1.1451510 ◽

2002 ◽

Vol 67 (1) ◽

pp. 188-196 ◽

Cited By ~ 1

Author(s):

Giuseppe Stanghellini ◽

Claudia Bonazzi

Keyword(s):

Seismic Data ◽

Low Frequency ◽

User Interaction ◽

Weather Conditions ◽

Processing Parameters ◽

Noise Rejection ◽

Bad Weather ◽

Marine Seismic ◽

Spurious Signals ◽

Incoherent Noise

The acquisition of marine seismic data is often affected by noise that introduces spurious signals. Due to the length of the receiver streamer, bad weather conditions can produce low‐frequency, high‐intensity incoherent noise and/or spikes that can be difficult to remove by means of conventional mathematical filters. In this paper we present two Fortran routines suitable to locate and remove the noise in the low and very low frequency ranges and to locate and suppress spikes. These two routines are designed to run without user interaction once the processing parameters are selected. Both routines are simple and compact, and can be included in any processing software.

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Streamer depth versus vessel and seismic interference noise

Geophysics ◽

10.1190/geo2016-0551.1 ◽

2017 ◽

Vol 82 (4) ◽

pp. P41-P51

Author(s):

Toan Dao ◽

Martin Landrø

Keyword(s):

Noise Level ◽

Cutoff Frequency ◽

Normal Modes ◽

Low Frequency ◽

Data Set ◽

The North ◽

Interference Noise ◽

Air Gun ◽

Seismic Surveying ◽

Marine Seismic

For marine seismic surveying, it is commonly assumed that the noise level decreases with depth. In addition, recent advances in broadband seismic have shown that a greater receiver depth is beneficial in preserving low-frequency data. However, in a heavily trafficked ocean, noise from other ships, including seismic interference, is a counteractive process in which the noise actually varies with depth. Normal modes can be used to explain and predict the ship noise and seismic interference noise level. We find that weather noise is dominant below the first mode’s cutoff frequency (approximately 6 Hz), ship noise is dominant from that frequency to the upper end of the useful seismic frequency band (80 Hz). We have used a data set in which the streamer was towed at 8, 45, and 60 m depths in three passes over the same area in the North Sea. The water depth is 135 m on average. We observe that the noise level at 45 and 60 m depth is approximately 1.6 times stronger than that at 8 m. We find that the air-gun energy is up to 46 dB stronger than the noise from the seismic vessel. However, the total noise from all the ships within several hundred kilometers radius can reduce the data quality.

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A new generation low frequency seismic vibrator

10.1190/segam2015-5713173.1 ◽

2015 ◽

Author(s):

Zhouhong Wei*

Keyword(s):

Low Frequency ◽

New Generation ◽

Seismic Vibrator

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GEOECOLOGICAL RISKS OF TECHNOGENIC NOISES AT LOW FREQUENCIES

Interexpo GEO-Siberia ◽

10.33764/2618-981x-2021-4-1-137-144 ◽

2021 ◽

Vol 4 (1) ◽

pp. 137-144

Author(s):

Oksana A. Kopylova ◽

Marat S. Khairetdinov

Keyword(s):

Numerical Analysis ◽

Low Frequency ◽

Vibration Velocity ◽

Acoustic Oscillations ◽

Railway Transport ◽

Seismic Vibration ◽

Time Analysis ◽

Low Frequencies ◽

Velocity Level ◽

Seismic Vibrator

The article considers the estimation and prevention problem of ecologically dangerous influence of technogenic noises generated by moving transport, such as heavy tracked and wheeled transport, railway transport. The influence on the man and the environment of a low-frequency controlled CV-40 seismic vibrator [1] used for seismological research separately is considered. The influence of vibrations located in the area of low and infra-low frequencies is estimated. The field records of technogenic noises are analyzed. Numerical analysis and estimation of levels of geoecological risks associated with seismic vibration in the ground and acoustic oscillations in the atmosphere are presented. Spectral and spectral-time analysis of technogenic noises records are performed. The main ecologically dangerous frequency areas, which are the most characteristic for these sources, are separated. The dynamics of changes of the vibration velocity level over distances for heavy wheeled and tracked types of transport has been determined.

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Airgun blasts used in marine seismic surveys have limited effects on mortality, and no sublethal effects on behaviour or gene expression, in the copepod Calanus finmarchicus

ICES Journal of Marine Science ◽

10.1093/icesjms/fsz126 ◽

2019 ◽

Vol 76 (7) ◽

pp. 2033-2044 ◽

Cited By ~ 3

Author(s):

David M Fields ◽

Nils Olav Handegard ◽

John Dalen ◽

Christiane Eichner ◽

Ketil Malde ◽

...

Keyword(s):

Escape Response ◽

Field Experiments ◽

Sublethal Effects ◽

Low Frequency ◽

Calanus Finmarchicus ◽

Sensory Threshold ◽

Seismic Surveys ◽

Commercially Important ◽

Or Gene ◽

Marine Seismic

Abstract Seismic surveys use airguns that emit low frequency high magnitude sound to detect subsea resources and to map seabed geology. The effect of seismic blasts on Calanus spp., a key food source for commercially important fish, was assessed in field experiments. Immediate mortality of copepods was significantly different from controls at distances of 5 m or less from the airguns. Mortality 1 week after the airgun blast was significantly higher—by 9% relative to controls—in the copepods placed 10 m from the airgun blast but was not significantly different from the controls at a distance of 20 m from the airgun blast. The increase in mortality—relative to controls—did not exceed 30% at any distance from the airgun blast. Only two genes changed in response to the airgun blast; however, their function is unknown. There were no sublethal effects of the seismic blasts on the escape performance or the sensory threshold needed to initiate an escape response at any of the distances from the airgun blast that were tested. Results from these experiments suggest that seismic blasts have limited effects on the mortality or escape response of Calanus sp. within 10 m of the blast and no measurable impact at greater distances.

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The resonant acoustic pulser—A continuous‐frequency marine seismic source

Geophysics ◽

10.1190/1.1441530 ◽

1983 ◽

Vol 48 (8) ◽

pp. 1082-1089 ◽

Cited By ~ 1

Author(s):

H. C. Hardee ◽

R. G. Hills

Keyword(s):

Low Frequency ◽

Harmonic Signal ◽

Seismic Source ◽

Acoustic Power ◽

Frequency Mode ◽

Resonant System ◽

Continuous Frequency ◽

Marine Seismic

A marine seismic source is described which produces a continuous low‐frequency (10–100 Hz) harmonic signal. High acoustic power levels (∼20 kW) are reached by using a resonant system. The seismic source has been successfully tested in lake and ocean environments. Geophysical applications are discussed and modifications are described which would allow the source to be operated in a swept‐frequency mode.

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SEISMIC SIGNATURES OF LARGE AIR GUNS

Geophysics ◽

10.1190/1.1440237 ◽

1971 ◽

Vol 36 (6) ◽

pp. 1162-1173 ◽

Cited By ~ 9

Author(s):

W. Harry Mayne ◽

Roy G. Quay

Keyword(s):

Energy Levels ◽

Low Frequency ◽

Experimental Tests ◽

Frequency Spectra ◽

Seismic Surveys ◽

Air Gun ◽

Absolute Energy ◽

Overall Performance ◽

Marine Seismic ◽

Effective Source

Large chamber air guns are a reliable and effective source of energy for marine seismic surveys. Air guns with chamber volumes of 300 and 1000 cubic inches demonstrate desirable low‐frequency responses and high absolute energy levels. Overall performance has been compromised, however, by the bubble effect. Previous attempts at minimizing the bubble response have resulted in loss of reliability, reduced power, or incomplete bubble suppression, or a combination thereof. In this paper, we present the results of experimental tests on air guns with 300 and 1000 cubic inch chambers and describe a divided‐chamber gun which greatly attenuates the bubble effect. Significant improvements in the width and flatness of the frequency spectra are demonstrated by analysis of the actual signatures obtained in deep water and with record sections comparing the results obtained with the standard and improved guns along an identical traverse. The bubble‐attenuating air gun simultaneously provides improved resolution, high absolute‐energy levels, and excellent reliability.

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