Amplitude control for resonant seismic source depth excursions

A computer implemented control method for a resonant seismic source, the method comprising:

• receiving, by a controller, pressure readings from a pressure sensor coupled to a resonant seismic source, wherein the resonant seismic source is towed in a marine environment;
• determining, by the controller, a depth of the resonant seismic source based on the pressure readings, wherein the depth is within a depth threshold range;
• determining, by the controller, a first change in the depth of the resonant seismic source to a depth outside of the depth threshold range;
• determining, by the controller, a first amplitude by which to reduce a resonant frequency produced by the resonant seismic source based on the first change in the depth of the resonant seismic source;
• reducing, by the controller, an amplitude of the resonant frequency produced by the resonant seismic source by the first amplitude, to obtain a reduced amplitude in response to determining the first amplitude of the resonant frequency produced by the resonant seismic source;
• determining, by the controller, a second change in the depth of the resonant seismic source from the depth outside of the depth threshold range to a depth within the depth threshold range;
• determining, by the controller, a second amplitude by which to increase the resonant frequency produced by the resonant seismic source based on the second change in depth of the resonant seismic source;
• and
• increasing the reduced amplitude of the resonant frequency produced by the resonant seismic source, to obtain an increased amplitude, in response to determining the second amplitude by which to increase the resonant frequency produced by the resonant seismic source.

A method of seismic exploration above a region of the subsurface of the earth containing structural or stratigraphic features conducive to the presence, migration, or accumulation of hydrocarbons, the method comprising:

• producing a resonant frequency at a first amplitude with a resonant seismic source at a tow depth, wherein the resonant seismic source comprises a piston moving within a mechanical movement range of the resonant seismic source between a first end stop and a second end stop;
• detecting a depth excursion from the tow depth;
• determining an oscillation range of the piston based on the depth excursion;
• determine that the oscillation range exceeds the mechanical movement range;
• determining a second amplitude by which to reduce the first amplitude of the piston based on the depth excursion from the tow depth;
• reducing the first amplitude of the piston by the second amplitude to obtain a reduced amplitude in response to determining that the oscillation range exceeds the mechanical movement range;
• to prevent the mass from contacting at least one of the first end stop or the second end stop;
• correcting the depth excursion to return the resonant seismic source to the tow depth;
• determining a third amplitude by which to increase the reduced amplitude of the piston based on the tow depth;
• and
• increasing the reduced amplitude by the third amplitude to produce the resonant frequency with the resonant seismic source at the tow depth.