This disclosure is related generally to marine surveying. An apparatus for generation of seismic waves in a body of water may include a wave generator. The apparatus may further include a housing defining an internal chamber having an open end. The housing may include baffles positioned between the open end and the wave generator. The housing may further include a vent positioned on an opposite end of the housing from the baffles.

An air gun for generating seismic waves in a marine environment includes a cylindrical body configured to hold compressed air and having plural air ports for releasing the compressed air from inside the cylindrical body, the cylindrical body extending along a longitudinal axis X, and an extension member attached externally to the body and extending along a radial axis R, which is perpendicular to the longitudinal axis X. The extension member promotes ambient water flowing inside an air bubble generated when the compressed air is released outside the body.

An air gun for generating seismic waves in a marine environment includes a cylindrical body configured to hold compressed air and having plural air ports for releasing the compressed air from inside the cylindrical body, the cylindrical body extending along a longitudinal axis X, and an extension member attached externally to the body and extending along a radial axis R, which is perpendicular to the longitudinal axis X. The extension member promotes ambient water flowing inside an air bubble generated when the compressed air is released outside the body.

An air gun for generating seismic waves in a marine environment includes a cylindrical body configured to hold compressed air and having plural air ports for releasing the compressed air from inside the cylindrical body, the cylindrical body extending along a longitudinal axis X, and an extension member attached externally to the body and extending along a radial axis R, which is perpendicular to the longitudinal axis X. The extension member promotes ambient water flowing inside an air bubble generated when the compressed air is released outside the body.

This disclosure is related generally to marine surveying. An apparatus for generation of seismic waves in a body of water may include a wave generator. The apparatus may further include a housing defining an internal chamber having an open end. The housing may include baffles positioned between the open end and the wave generator. The housing may further include a vent positioned on an opposite end of the housing from the baffles.

In order to avoid complicated and unpredictable effects on the wavefields emitted by air guns activated at different times, methods and systems of the current disclosure are directed to computationally designing a sequence for activating subsets of air guns in a time distributed manner that minimizes the effects of air in the water surrounding the source. The sequence may be used with discrete and continuously recorded marine surveys.

A marine seismic data acquisition system, comprising: a seismic source arrangement comprising: a first seismic source adapted to be towed at a first predetermined depth and a second seismic source adapted to be towed at a second predetermined depth, which is deeper than the first predetermined depth, wherein, in use, the first seismic source transmits pulses, each pulse comprising an upwardly-travelling pressure wavefield, which is reflected at the sea/air interface to become a downwardly-travelling ghost pressure wavefield, and a downwardly-travelling primary pressure wavefield, and the second seismic source transmits pulses, each pulse comprising an upwardly-travelling pressure wavefield, which is reflected at the sea/air interface to become a downwardly-travelling ghost pressure wavefield, and a downwardly-travelling primary pressure wavefield, and wherein the first predetermined depth and the magnitude of the peak pressure of the upwardly-travelling pressure wavefield produced by the first seismic source are selected to create an anelastic region at the sea surface having a reflection coefficient of between 0.45 and 0, the system further comprising a receiver for receiving the pulses transmitted from the seismic source arrangement and for extracting data from within a predetermined frequency band of interest.

A marine seismic data acquisition system, comprising: a seismic source arrangement comprising: a first seismic source adapted to be towed at a first predetermined depth and a second seismic source adapted to be towed at a second predetermined depth, which is deeper than the first predetermined depth, wherein, in use, the first seismic source transmits pulses, each pulse comprising an upwardly-travelling pressure wavefield, which is reflected at the sea/air interface to become a downwardly-travelling ghost pressure wavefield, and a downwardly-travelling primary pressure wavefield, and the second seismic source transmits pulses, each pulse comprising an upwardly-travelling pressure wavefield, which is reflected at the sea/air interface to become a downwardly-travelling ghost pressure wavefield, and a downwardly-travelling primary pressure wavefield, and wherein the first predetermined depth and the magnitude of the peak pressure of the upwardly-travelling pressure wavefield produced by the first seismic source are selected to create an anelastic region at the sea surface having a reflection coefficient of between 0.45 and 0, the system further comprising a receiver for receiving the pulses transmitted from the seismic source arrangement and for extracting data from within a predetermined frequency band of interest.