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.

Time-Lapse Monitoring of Daily Velocity Changes in Binchuan, Southwestern China, Using Large-Volume Air-Gun Source Array Data

2022 ◽  
Author(s):  
Yi Luan ◽  
Hongfeng Yang ◽  
Baoshan Wang ◽  
Wei Yang ◽  
Weitao Wang ◽  
...  
Keyword(s):  
Large Volume ◽  
Seismic Data ◽  
Temporal Changes ◽  
Air Pressure ◽  
Southwestern China ◽  
Long Period ◽  
Air Gun ◽  
Velocity Variations ◽  
Velocity Changes ◽  
Source Array

Abstract Temporal changes of seismic velocities in the Earth’s crust can be induced by stress perturbations or material damage from reasons such as strong ground motion, volcanic activities, and atmospheric effects. However, monitoring the temporal changes remains challenging, because most of them generally exist in small travel-time differences of seismic data. Here, we present an excellent case of daily variations of the subsurface structure detected using a large-volume air-gun source array of one-month experiment in Binchuan, Yunnan, southwestern China. The seismic data were recorded by 12 stations within ∼10 km away from the source and used to detect velocity change in the crust using the deconvolution method and sliding window cross-correlation method, which can eliminate the “intercept” error when cutting the air-gun signals and get the real subsurface variations. Furthermore, the multichannel singular spectral analysis method is used to separate the daily change (∼1 cycle per day) from the “long-period” change (<1 cycle per day) or noise. The result suggests that the daily velocity changes at the two nearest stations, 53277 (offset ∼700 m) and 53278 (offset ∼2.3 km), are well correlated with air temperature variation with a time lag of 5.0 ± 1.5 hr, which reflects that the velocity variations at the subsurface are likely attributed to thermoelastic strain. In contrast, both daily and long-period velocity changes at distant stations correlate better with the varying air pressure than the temperature, indicating that the velocity variations at deeper depth are dominated by the elastic loading of air pressure. Our results demonstrate that the air-gun source is a powerful tool to detect the velocity variation of the shallow crust media.

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.

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.

4D-READY SEISMIC WITH Q-MARINE

2001 ◽  
Vol 41 (1) ◽  
pp. 671
Author(s):  
T. Brice ◽  
L. Larsen ◽  
S. Morice ◽  
M. Svendsun
Keyword(s):  
Seismic Data ◽  
Noise Suppression ◽  
Processing System ◽  
Seismic Signal ◽  
Coherent Noise ◽  
Data Adaptive ◽  
A New Technique ◽  
Marine Seismic ◽  
Source Array ◽  
Array Geometry

A new concept for acquiring calibrated towed streamer seismic data is introduced through a new acquisition and processing system called ‘Q-Marine’. The specification of the new system has been defined by rigorous analysis of the factors that limit the sensitivity of seismic data in 4D studies and imaging. New sensor and streamer technology, new source technology and advances in positioning techniques and data processing have addressed these limitations.Sensitivity analysis revealed that the most significant perturbations to the seismic signal are swell noise and sensor sensitivity variations. Conventional analog groups of hydrophones are designed to suppress swell noise however a new technique for data-adaptive coherent noise attenuation delivers even greater noise suppression for densely spatially sampled single-sensor data.Although modern source controllers provide accurate airgun firing control, the signature of an airgun array may vary from shot to shot. This can be due to factors such as changes in the array geometry, air pressure variations, depth variations and wave action. A method for estimating the far-field signature of a source array is the Notional Source Method (proprietary to Schlumberger) which has been steadily refined since its first disclosure. A recent development compensates for variation in source array geometry by monitoring the position and azimuth of each subarray using GPS receivers mounted on the floats.New calibrated positioning and streamer control systems are part of the new acquisition system. Active vertical and lateral streamer control is achieved using steerable birds and positioning uncertainty is reduced through an in-built fully braced acoustic ranging system.Calibrated marine seismic data are achieved through quantifying the source output, the sensor responses and positioning uncertainty. The consequential improvements in seismic fidelity result in better imaging and more reliable 4D analysis.

Attenuation of seismic swell noise using convolutional neural networks in frequency domain and transfer learning

2020 ◽  
Vol 8 (4) ◽  
pp. T941-T952
Author(s):  
Jiachun You ◽  
Yajuan Xue ◽  
Junxing Cao ◽  
Canping Li
Keyword(s):  
Frequency Domain ◽  
Transfer Learning ◽  
Seismic Data ◽  
Signal To Noise Ratio ◽  
Structural Similarity ◽  
Fine Tuning ◽  
Network Parameter ◽  
Marine Seismic ◽  
The Time Domain

Because swell noises are very common in marine seismic data, it is extremely important to attenuate them to improve the signal-to-noise ratio (S/N). Compared to process noises in the time domain, we have built a frequency-domain convolutional neural network (CNN) based on the short-time Fourier transform to address swell noises. In the numerical experiments, we quantitatively evaluate the denoising performances of the time- and frequency-domain CNNs, compare the impacts of network structures on attenuating swell noises, and study how network parameter choices impact the quality of the denoised signal based on peak S/N, structural similarity, and root-mean-square-error indices. These results help us to build an optimal CNN model. Furthermore, to illustrate the superiority of our proposed method, we compare the conventional and proposed CNN methods. To address the generalization capability of CNN, we adopt transfer learning by using fine tuning to adjust the weights of the pretrained model with a small amount of target data. The application of transfer learning improves the quality of the denoised images, which further proves that our proposed method with transfer learning has the potential to be deployed in actual seismic data acquisition.

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.

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.

Formation geological depth image according to refraction and reflection marine seismic data

2017 ◽  
Vol 39 (6) ◽  
pp. 106-121
Author(s):  
A. O. Verpahovskaya ◽  
V. N. Pilipenko ◽  
Е. V. Pylypenko
Keyword(s):  
Seismic Data ◽  
Depth Image ◽  
Marine Seismic

PROCESSING AND IMAGING OF MARINE SEISMIC DATA FROM THE JEQUITINHONHA BASIN (BAHIA, BRAZIL)

2016 ◽  
Vol 33 (3) ◽  
Author(s):  
Lourenildo W.B. Leite ◽  
J. Mann ◽  
Wildney W.S. Vieira
Keyword(s):  
Seismic Data ◽  
Sedimentary Basins ◽  
Study Results ◽  
Marine Seismic ◽  
Present Case Study

ABSTRACT. The present case study results from a consistent processing and imaging of marine seismic data from a set collected over sedimentary basins of the East Brazilian Atlantic. Our general aim is... RESUMO. O presente artigo resulta de um processamento e imageamento consistentes de dados sísmicos marinhos de levantamento realizado em bacias sedimentares do Atlântico do Nordeste...

SOUTH GEORGIA MICROCONTINENT: CURRENT TECTONIC SETTING FROM GPS AND MARINE SEISMIC DATA

2019 ◽  
Author(s):  
Ian W.D. Dalziel ◽  
◽  
Robert Smalley ◽  
Lawrence A. Lawver ◽  
Demian Gomez ◽  
...  
Keyword(s):  
Seismic Data ◽  
Tectonic Setting ◽  
South Georgia ◽  
Marine Seismic
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