The music of marine seismic: A marine vibrator system based on folded surfaces

2020 ◽  
Vol 39 (4) ◽  
pp. 254-263
Author(s):  
Okwudili C. Orji ◽  
Mattias Oscarsson-Nagel ◽  
Walter Söllner ◽  
Endrias G. Asgedom ◽  
Øystein Trætten ◽  
...  
Keyword(s):  
Seismic Data ◽  
Frequency Tuning ◽  
Synthetic Data ◽  
Harmonic Distortion ◽  
Low Frequency ◽  
Source Control ◽  
Environmental Friendliness ◽  
Air Gun ◽  
Frequency Module ◽  
Marine Seismic

Marine vibrators have bespoke geophysical benefits that are yet to be harnessed because of robustness and efficiency issues. We have developed a new marine vibrator source technology that is efficient and stable. The source technology overcomes the historical problems of inefficiency and robustness by using folded surface technology and resonance frequency tuning. We show measured output examples that demonstrate that the folded surface concept combined with small displacements can provide the required output levels. Our source system consists of a low-frequency module covering 1–10 Hz and a high-frequency module covering 10–125 Hz. The source control system has shown high stability and precision and can handle harmonic distortion. With the aid of synthetic data examples, we demonstrate that seismic data acquired using marine vibrators in either intermittent or continuous mode can be processed. Finally, we demonstrate the environmental friendliness of the source in comparison to air gun-based sources.

Delaying the source ghost to improve the ultralow-frequency response of a marine air-gun source

Geophysics ◽  
2020 ◽  
Vol 85 (5) ◽  
pp. P45-P51
Author(s):  
Honglei Shen ◽  
Thomas Elboth ◽  
Chunhui Tao ◽  
Gang Tian ◽  
Hanchuang Wang ◽  
...  
Keyword(s):  
Seismic Data ◽  
Waveform Inversion ◽  
Low Frequency ◽  
Ultralow Frequency ◽  
Full Waveform ◽  
Air Gun ◽  
Marine Source ◽  
Frequency Output ◽  
Marine Seismic ◽  
Marine Air

The competing effect between the fundamental bubble and its source-ghost response results in a strong attenuation of the lowest frequencies (below 7 Hz). This loss cannot be compensated easily by adjusting the source depth. Consequently, the low-frequency content in marine seismic data is not optimal, degrading the performance of low-frequency dependent processing approaches, such as full-waveform inversion. To overcome this, we have developed an additional source to counteract the ghost from the main source. In this situation, the fundamental bubble is characterized by the depth of the main source, whereas the ghost response is characterized by the summed depth of the main and additional sources. This source setup mitigates the competing effect and reduces the suppression of ultralow frequencies. Compared with a conventional horizontal source, our source design will reduce the mid- to high-frequency output, which may be beneficial in situations in which environmental constraints limit the maximum allowed output of a marine source.

Application of complex-trace analysis to seismic data for random-noise suppression and temporal resolution improvement

Geophysics ◽  
2006 ◽  
Vol 71 (3) ◽  
pp. V79-V86 ◽  
Author(s):  
Hakan Karsli ◽  
Derman Dondurur ◽  
Günay Çifçi
Keyword(s):  
Seismic Data ◽  
Trace Analysis ◽  
Noise Suppression ◽  
Single Channel ◽  
Random Noise ◽  
Synthetic Data ◽  
Low Frequency ◽  
Bright Spot ◽  
Phase Information ◽  
Resolution Improvement

Time-dependent amplitude and phase information of stacked seismic data are processed independently using complex trace analysis in order to facilitate interpretation by improving resolution and decreasing random noise. We represent seismic traces using their envelopes and instantaneous phases obtained by the Hilbert transform. The proposed method reduces the amplitudes of the low-frequency components of the envelope, while preserving the phase information. Several tests are performed in order to investigate the behavior of the present method for resolution improvement and noise suppression. Applications on both 1D and 2D synthetic data show that the method is capable of reducing the amplitudes and temporal widths of the side lobes of the input wavelets, and hence, the spectral bandwidth of the input seismic data is enhanced, resulting in an improvement in the signal-to-noise ratio. The bright-spot anomalies observed on the stacked sections become clearer because the output seismic traces have a simplified appearance allowing an easier data interpretation. We recommend applying this simple signal processing for signal enhancement prior to interpretation, especially for single channel and low-fold seismic data.

scholarly journals Deep learning for low-frequency extrapolation from multioffset seismic data

Geophysics ◽  
2019 ◽  
Vol 84 (6) ◽  
pp. R989-R1001 ◽  
Author(s):  
Oleg Ovcharenko ◽  
Vladimir Kazei ◽  
Mahesh Kalita ◽  
Daniel Peter ◽  
Tariq Alkhalifah
Keyword(s):  
Deep Learning ◽  
Seismic Data ◽  
Signal To Noise Ratio ◽  
Waveform Inversion ◽  
Low Frequency ◽  
Low Frequencies ◽  
Seismic Surveys ◽  
Full Waveform ◽  
Frequency Components ◽  
Marine Seismic

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.

Single water gun far‐field pressure signatures estimated from near‐field measurements

Geophysics ◽  
1985 ◽  
Vol 50 (2) ◽  
pp. 257-261 ◽  
Author(s):  
M. H. Safar
Keyword(s):  
High Resolution ◽  
Data Acquisition ◽  
Seismic Data ◽  
Near Field ◽  
Field Measurements ◽  
Reference Source ◽  
Far Field ◽  
Air Gun ◽  
Seismic Data Acquisition ◽  
Marine Seismic

An important recent development in marine seismic data acquisition is the introduction of the Gemini technique (Newman, 1983, Haskey et al., 1983). The technique involves the use of a single Sodera water gun as a reference source together with the conventional air gun or water gun array which is fired a second or two after firing the reference source. The near‐field pressure signature radiated by the reference source is monitored continuously. The main advantage of the Gemini technique is that a shallow high;resolution section is recorded simultaneously with that obtained from the main array.

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

Geophysics ◽  
2002 ◽  
Vol 67 (1) ◽  
pp. 188-196 ◽  
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.

scholarly journals Streamer depth versus vessel and seismic interference noise

Geophysics ◽  
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.

Marine vibrators and the Doppler effect

Geophysics ◽  
1988 ◽  
Vol 53 (11) ◽  
pp. 1388-1398 ◽  
Author(s):  
William H. Dragoset
Keyword(s):  
Gulf Of Mexico ◽  
Doppler Effect ◽  
Synthetic Data ◽  
Simple Relationship ◽  
Phase Dispersion ◽  
Air Gun ◽  
Before And After ◽  
Doppler Factor ◽  
The Doppler Effect ◽  
Marine Seismic

Marine seismic data acquired with a moving vibrator suffer phase dispersion caused by Doppler shifting of the source sweep function. The dispersion for a particular reflection event depends upon frequency, the type of sweep function, and the Doppler factor associated with that event. Synthetic vibrator data show that, at typical ship speeds, the Doppler factors for steeply dipping events are big enough to cause phase dispersion as large as several hundred degrees. If unaccounted for, such dispersive effects could make a moving marine vibrator unacceptable for imaging steep dips. In a constant‐offset section, the Doppler factor for a reflection event is the product of ship speed and the event’s time dip. That key, simple relationship allows a two‐dimensional f-k filter to remove the phase dispersion caused by the Doppler effect. Comparisons of both synthetic data and Gulf of Mexico field data, before and after application of the phase‐correcting filter, show that the filter improves steep‐dip imaging in marine vibrator data. For the Gulf of Mexico line, steep dips are imaged just as well in the phase‐corrected vibrator data as in air‐gun data.

Desired seismic characteristics of an air gun source

Geophysics ◽  
1982 ◽  
Vol 47 (9) ◽  
pp. 1273-1284 ◽  
Author(s):  
Ken Larner ◽  
Dave Hale ◽  
Sharon Misener Zinkham ◽  
Charles Hewlitt
Keyword(s):  
Seismic Data ◽  
Fine Tuning ◽  
Source Strength ◽  
Air Gun ◽  
Total Noise ◽  
Weak Reflection ◽  
Effective Level ◽  
Marine Seismic ◽  
Air Capacity ◽  
Source Array

Marine seismic data are generally contaminated with both “bubble pulses” and “tow noise.” Air gun sources are deployed in arrays designed to reduce the effective level of the bubble pulses. Because the signal from a source array is profoundly altered by the filter characteristics of the earth and because the received signal is subjected to noise‐generating computer processes such as deconvolution, array designs should be optimized to obtain the minimum aggregate noise, and hence the greatest reflection stand‐out, in output traces. For a fixed air‐compressor capacity, a trade‐off in array design exists between maximizing source strength and the fine tuning required to maximize the first‐pulse‐to‐bubble ratio. Except for shallow, high‐resolution surveys where the deconvolution step can be bypassed, optimum suppression of total noise in the output can often be obtained using the available air capacity to increase the source strength of a moderately tuned array, rather than to achieve fine tuning of the array. Processing noise produced by deconvolution will prevent detection of a weak reflection closely following a strong one if the ratio of the two is more than about 21 dB, no matter how finely tuned the source array may be.

PC‐based acquisition and processing of high‐resolution marine seismic data

Geophysics ◽  
1996 ◽  
Vol 61 (6) ◽  
pp. 1804-1812 ◽  
Author(s):  
Ho‐Young Lee ◽  
Byung‐Koo Hyun ◽  
Young‐Sae Kong
Keyword(s):  
High Resolution ◽  
Seismic Data ◽  
Spectral Characteristics ◽  
Processing System ◽  
Band Pass Filter ◽  
Pass Filter ◽  
Optical Disk Drive ◽  
Air Gun ◽  
Marine Seismic

We have improved the quality of high‐resolution marine seismic data using a simple PC‐based acquisition and processing system. The system consists of a PC, an A/D converter, and a magneto‐optical disk drive. The system has been designed to acquire single‐channel data at up to 60,000 samples per second and to perform data processing of seismic data by a simple procedure. Test surveys have been carried out off Pohang, southern East Sea of Korea. The seismic systems used for the test were an air gun and a 3.5 kHz sub‐bottom profiling system. Spectral characteristics of the sources were analyzed. Simple digital signal processes which include gain recovery, deconvolution, band‐pass filter, and swell filter were performed. The quality of seismic sections produced by the system is greatly enhanced in comparison to analog sections. The PC‐based system for acquisition and processing of high‐resolution marine seismic data is economical and versatile.

SEISMIC SIGNATURES OF LARGE AIR GUNS

Geophysics ◽  
1971 ◽  
Vol 36 (6) ◽  
pp. 1162-1173 ◽  
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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