“Single bubble” air‐gun array for deep exploration

Geophysics ◽  
1993 ◽  
Vol 58 (3) ◽  
pp. 366-382 ◽  
Author(s):  
F. Avedik ◽  
V. Renard ◽  
J. P. Allenou ◽  
B. Morvan
Keyword(s):  
Energy Content ◽  
Low Frequency ◽  
Pulse Generation ◽  
Acoustic Energy ◽  
Petroleum Exploration ◽  
Single Bubble ◽  
Seismic Exploration ◽  
Deep Penetration ◽  
Air Gun ◽  
Marine Seismic

Large tuned air‐gun arrays operated in off‐shore petroleum exploration are also used for deep penetration marine seismic reflection surveys conducted to define structures in the earth’s crust. Because of the attenuation of higher frequencies, the useful upper frequency limit of these records is usually about 50–60 Hz. The aim of this paper is to report on a method of seismic pulse generation that preferentially concentrates the air gun’s energy in the low range of the seismic frequency band by centering the output on the first “bubble pulse” instead of the initial (primary) pulse. Experimental results show that, due to the increased low‐frequency energy content of this “single bubble” pulse, air‐gun arrays considerably reduced both in size and volume can generate the necessary acoustic energy for deep seismic exploration.

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.

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.

Modeling air gun signatures in marine seismic exploration considering multiple physical factors

2010 ◽  
Vol 7 (2) ◽  
pp. 158-165 ◽  
Author(s):  
Guo-Fa Li ◽  
Ming-Qiang Cao ◽  
Hao-Lin Chen ◽  
Cheng-Zhou Ni
Keyword(s):  
Seismic Exploration ◽  
Physical Factors ◽  
Air Gun ◽  
Marine Seismic

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.

Marine seismic acquisition: efficiency and environment, new technologies applied in Australia

2017 ◽  
Vol 57 (2) ◽  
pp. 704 ◽  
Author(s):  
Martin Bayly ◽  
Michelle Tham ◽  
Peter Watterson ◽  
Binghui Li ◽  
Kevin Moran
Keyword(s):  
Environmental Impact ◽  
New Technologies ◽  
New Technology ◽  
Seismic Exploration ◽  
Exposure Level ◽  
North West ◽  
Optimal Output ◽  
Air Gun ◽  
Seismic Acquisition ◽  
Marine Seismic

The design of successful marine seismic surveys is driven by many factors, two prime issues being efficiency and environmental impact. Efficiency is primarily driven by reduction of non-productive time and creating the largest sub-surface illumination area possible in the shortest time. In addition, public opinion and governmental regulations are requiring the industry to minimise their environmental impact. One aspect is reducing the overall sound exposure level (SEL) of the source into the marine environment. Using recent Australian examples, we will discuss and demonstrate the use of two new technology groups that address these concerns. The first is the use of a new type of seismic air-gun with optimal output over the range of frequencies commonly used in seismic exploration, while limiting potential environmental effects from unnecessary high-frequency emissions. The second is continuous data acquisition along the entire boat traverse, including the turns, thereby reducing non-productive vessel time. Both are described with examples from a recent survey acquired offshore north-west Australia.

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.

Shot repetition: An alternative seismic blending code in marine acquisition

Geophysics ◽  
2018 ◽  
Vol 83 (6) ◽  
pp. P29-P37 ◽  
Author(s):  
Sixue Wu ◽  
Gerrit Blacquière ◽  
Gert-Jan Adriaan van Groenestijn
Keyword(s):  
Source Code ◽  
Seismic Exploration ◽  
Data Quality Control ◽  
Time Data ◽  
Alternative Source ◽  
Seismic Surveys ◽  
Air Gun ◽  
Seismic Acquisition ◽  
Marine Seismic ◽  
Source Encoding

In blended seismic acquisition, or simultaneous source seismic acquisition, source encoding is essential at the acquisition stage to allow for separation of the blended sources at the processing stage. In land seismic surveys, the vibroseis sources may be encoded with near-orthogonal sweeps for blending. In marine seismic surveys, the sweep type of source encoding is difficult because the main source type in marine seismic exploration is the air-gun array, which has an impulsive character. Another issue in marine streamer seismic data acquisition is that the spatial source sampling is generally coarse. This hinders the deblending performance of algorithms based on the random time delay blending code that inherently requires a dense source sampling because they exploit the signal coherency in the common-receiver domain. We have developed an alternative source code called shot repetition that exploits the impulsive character of the marine seismic source in blending. This source code consists of repeated spikes of ones and can be realized physically by activating a broadband impulsive source more than once at (nearly) the same location. Optimization of the shot-repetition type of blending code was done to improve the deblending performance. As a result of using shot repetition, the deblending process can be carried out in individual shot gathers. Therefore, our method has no need for a regular dense source sampling: It can cope with irregular sparse source sampling; it can help with real-time data quality control. In addition, the use of shot repetition is beneficial for reducing the background noise in the deblended data. We determine the feasibility of our method on numerical examples.

scholarly journals Low-Frequency Expansion Approach for Seismic Data Based on Compressed Sensing in Low SNR

2021 ◽  
Vol 11 (11) ◽  
pp. 5028
Author(s):  
Miaomiao Sun ◽  
Zhenchun Li ◽  
Yanli Liu ◽  
Jiao Wang ◽  
Yufei Su
Keyword(s):  
Reflection Coefficient ◽  
Compressed Sensing ◽  
Objective Function ◽  
Low Frequency ◽  
Original Data ◽  
Seismic Exploration ◽  
High Signal ◽  
Inversion Process ◽  
Frequency Information ◽  
Low Snr

Low-frequency information can reflect the basic trend of a formation, enhance the accuracy of velocity analysis and improve the imaging accuracy of deep structures in seismic exploration. However, the low-frequency information obtained by the conventional seismic acquisition method is seriously polluted by noise, which will be further lost in processing. Compressed sensing (CS) theory is used to exploit the sparsity of the reflection coefficient in the frequency domain to expand the low-frequency components reasonably, thus improving the data quality. However, the conventional CS method is greatly affected by noise, and the effective expansion of low-frequency information can only be realized in the case of a high signal-to-noise ratio (SNR). In this paper, well information is introduced into the objective function to constrain the inversion process of the estimated reflection coefficient, and then, the low-frequency component of the original data is expanded by extracting the low-frequency information of the reflection coefficient. It has been proved by model tests and actual data processing results that the objective function of estimating the reflection coefficient constrained by well logging data based on CS theory can improve the anti-noise interference ability of the inversion process and expand the low-frequency information well in the case of a low SNR.

scholarly journals Estimation of permeability and saturation based on imaginary component of complex resistivity spectra: A laboratory study

2020 ◽  
Vol 12 (1) ◽  
pp. 299-306
Author(s):  
Jiang Jia ◽  
Shizhen Ke ◽  
Junjian Li ◽  
Zhengming Kang ◽  
Xuerui Ma ◽  
...  
Keyword(s):  
Water Saturation ◽  
Pore Space ◽  
Evaluation Model ◽  
Low Frequency ◽  
Petroleum Exploration ◽  
Western China ◽  
Imaginary Component ◽  
Estimation Model ◽  
Complex Resistivity ◽  
Linear Relationships

AbstractLow-frequency resistivity logging plays an important role in the field of petroleum exploration, but the complex resistivity spectrum of rock also contains a large amount of information about reservoir parameters. The complex resistivity spectra of 15 natural sandstone cores from western China, with different water saturations, were measured with an impedance analyzer. The pore space of each core was saturated with NaCl solution, and measurements were collected at a frequency range of 40–15 MHz. The results showed a linear relationship between the real resistivity at 1 kHz and the maximum values of imaginary resistivity for each core with different water saturations. The slopes of the linear best-fit lines had good linear relationships with the porosity and the permeability of cores. Based on this, a permeability estimation model was proposed and tested. In addition, the maxima of imaginary resistivity had power exponential relationships with the porosity and the water saturation of the cores. A saturation evaluation model based on the maxima of imaginary resistivity was established by imitating Archie’s formula. The new models were found to be feasible for determining the permeability and saturation of sandstone based on complex resistivity spectrum measurements. These models advance the application of complex resistivity spectrum in petrophysics.

Collective oscillations in bubble clouds

2011 ◽  
Vol 680 ◽  
pp. 114-149 ◽  
Author(s):  
ZORANA ZERAVCIC ◽  
DETLEF LOHSE ◽  
WIM VAN SAARLOOS
Keyword(s):  
Frequency Response ◽  
Acoustic Field ◽  
Low Frequency ◽  
Acoustic Energy ◽  
Viscous Damping ◽  
Edge States ◽  
Bubble Cloud ◽  
Collective Oscillations ◽  
The Individual ◽  
Bubble Oscillations

In this paper the collective oscillations of a bubble cloud in an acoustic field are theoretically analysed with concepts and techniques of condensed matter physics. More specifically, we will calculate the eigenmodes and their excitabilities, eigenfrequencies, densities of states, responses, absorption and participation ratios to better understand the collective dynamics of coupled bubbles and address the question of possible localization of acoustic energy in the bubble cloud. The radial oscillations of the individual bubbles in the acoustic field are described by coupled linearized Rayleigh–Plesset equations. We explore the effects of viscous damping, distance between bubbles, polydispersity, geometric disorder, size of the bubbles and size of the cloud. For large enough clusters, the collective response is often very different from that of a typical mode, as the frequency response of each mode is sufficiently wide that many modes are excited when the cloud is driven by ultrasound. The reason is the strong effect of viscosity on the collective mode response, which is surprising, as viscous damping effects are small for single-bubble oscillations in water. Localization of acoustic energy is only found in the case of substantial bubble size polydispersity or geometric disorder. The lack of localization for a weak disorder is traced back to the long-range 1/r interaction potential between the individual bubbles. The results of the present paper are connected to recent experimental observations of collective bubble oscillations in a two-dimensional bubble cloud, where pronounced edge states and a pronounced low-frequency response had been observed, both consistent with the present theoretical findings. Finally, an outlook to future possible experiments is given.

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