An alternative method for modeling close-range interactions between air guns

Barker, Daniel S.; Landrø, Martin

doi:10.1190/geo2013-0141.1

Cited by 7 publications

(3 citation statements)

References 12 publications

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“…When airguns are close enough for their bubbles to interact or merge, the guns are referred to as a cluster. In this case, the bubble period is approximately proportional to the cubic root of the total volume of the cluster (Strandenes and Vaage ; Barker and Landrø ). Airgun clusters have been used to increase the low‐frequency content of airgun arrays and improve imaging of deep targets (Shimizu et al .…”

Section: Physics and Numerical Modelling Of Pneumatic Sourcesmentioning

confidence: 99%

Research Note: Low‐frequency pneumatic seismic sources

Chelminski

Watson

Ronen

2019

Geophysical Prospecting

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Pneumatic seismic sources, commonly known as airguns, have been serving us well for decades, but there is an increasing need for sources with improved low‐frequency signal and reduced environmental impact. In this paper, we present a new pneumatic source that is designed to achieve these goals by operating with lower pressures and larger volumes. The new source will release more air creating larger bubbles with longer bubble periods than airguns. The release of the air will be tuned so that the rise time will be longer and the sound pressure level and its slope will be lower. Certain engineering features will eliminate cavitation. Larger bubbles increase low‐frequency content of the signal, longer rise times decrease mid‐frequency content and the elimination of cavitation reduces high‐frequency content. We have not yet built a full‐scale version of the new source. However, we have manufactured a small‐scale low‐pressure source incorporating most of the engineering features, and tested it in a lake. Here, we present the lake data that, as expected, show a significant reduction in the sound pressure level, increase in rise time, decrease in slope and decrease in high‐frequency content while maintaining the same low‐frequency content when the source prototype is operated at low pressure compared with high pressure. Synthetic data produced by numerical modelling of the full‐scale proposed pneumatic source suggest that the new source will improve the low‐frequency content and can produce geophysically useful signal down to 1 Hz.

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Section: Physics and Numerical Modelling Of Pneumatic Sourcesmentioning

confidence: 99%

Research Note: Low‐frequency pneumatic seismic sources

Chelminski

Watson

Ronen

2019

Geophysical Prospecting

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“…Our numerical results agree well with the experimental images, for the bubble surface and free surface shapes, both before and after jet impact. With the validated model, we simulate the interaction of a toroidal bubble and a free surface near a rigid boundary, which are associated with applications for underwater explosions (Cole, 1948;Chahine and Perdue, 1990;Klaseboer et al, 2005a;Hung and Hwangfu, 2010; and seismic airgun operations (Caldwell, 2002;Cox et al, 2004;Madsen et al, 2006;Chen et al, 2008;and Barker and Landrø, 2014). The bubble and free surface interaction near a vertical boundary was modelled by Zhang et al (1998), Wang et al (2003), Wang (2004), and Liu et al (2013), using the BIM model.…”

Section: -2mentioning

confidence: 99%

The motion of a 3D toroidal bubble and its interaction with a free surface near an inclined boundary

Liu

Wang

et al. 2016

Physics of Fluids

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The numerical modelling of 3D toroidal bubble dynamics is a challenging problem due to the complex topological transition of the flow domain, and physical and numerical instabilities, associated with jet penetration through the bubble. In this paper, this phenomenon is modelled using the boundary integral method (BIM) coupled with a vortex ring model. We implement a new impact model consisting of the refined local mesh near the impact location immediately before and after impact, and a surgical cut at a high resolution forming a smooth hole for the transition from a singly connected to doubly connected form. This enables a smooth transition from a singly connected bubble to a toroidal bubble. The potential due to a vortex ring is reduced to the line integral along the vortex ring. A new mesh density control technique is described to update the bubble and free surfaces, which provides a high mesh quality of the surfaces with the mesh density in terms of the curvature distribution of the surface. The pressure distribution in the flow field is calculated by using the Bernoulli equation, where the partial derivative of the velocity potential in time is calculated using the BIM model to avoid numerical instabilities. Experiments are carried out for the interaction of a spark generated bubble with a free surface near a boundary, which is captured by using a high speed camera. Our numerical results agree well with the experimental images, for the bubble and free surface shapes for both before and after jet impact. New results are analyzed for the interaction of a toroidal bubble with a free surface near a vertical boundary and a sloping boundary, at both negative and positive angles to the vertical, without and with buoyancy, respectively. After jet impact, the bubble becomes a bubble ring, whose cross section is much thinner at the distal side from the boundary. It subsequently breaks into a crescent shaped bubble. The free surface displays singular features at its intersection with an inclined boundary.

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“…The first example of air-gun modeling was presented by Ziolkowski (1970). Later exam-ples of modeling of air guns can be found in Landrø (1992) and Barker and Landrø (2014).…”

Section: Introductionmentioning

confidence: 99%

Comparing the broadband acoustic frequency response of single, clustered, and arrays of marine air guns

Landrø

Langhammer

2020

GEOPHYSICS

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Field data acquired from a seismic vessel by a seabed hydrophone is used to analyze the broadband response (10 Hz to 62.5 kHz) for various source configurations: single air guns, clustered air guns, and a full array consisting of 30 air guns. The various parts of the acoustic signal are analyzed in detail, and it is found that a high-frequency signal arriving prior to the main peak of a single air-gun signal most likely is caused by small vapor cavities collapsing at or close to the surface of the gun. This is confirmed by high-speed photographs taken when a small air gun is fired in a water tank. When the full array is used, a second type of cavitation signal is observed: ghost cavitation caused by acoustic stimulation by the negative pressure that is backscattered from the free surface. As this ghost signal from 30 different guns arrives at a specific location in the water, cavities might be formed, and they create a high-frequency acoustic signal.

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An alternative method for modeling close-range interactions between air guns

Cited by 7 publications

References 12 publications

Research Note: Low‐frequency pneumatic seismic sources

Research Note: Low‐frequency pneumatic seismic sources

The motion of a 3D toroidal bubble and its interaction with a free surface near an inclined boundary

Comparing the broadband acoustic frequency response of single, clustered, and arrays of marine air guns

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