Abstract: Method for seismic prospecting using counter-rotating (207-208) eccentric-mass (201, 202) vibrator (CREMV) technology adapted as vibrator sources for seismic prospecting to produce controlled sweeps, as in the manner used in modern seismic prospecting, but with large forces at low frequencies, e.g. forces >275 kN at frequencies between 1 and 5 Hz. This is achieved by adapting the CREMV to enable rotational frequency and the eccentricity (205, 206) of the masses relative to their rotation axes (203-204) to be varied independently and simultaneously, and by designing the CREMV such that the radius of rotation of the center of mass of each rotating mass is on the order of 50 cm or more. The low frequency data obtained from such a seismic source enables improved detection and resolution of subsurface structures and better determination of subsurface properties.

Abstract: Method for seismic prospecting using counter-rotating (207-208) eccentric-mass (201, 202) vibrator (CREMV) technology adapted as vibrator sources for seismic prospecting to produce controlled sweeps, as in the manner used in modern seismic prospecting, but with large forces at low frequencies, e.g. forces >275 kN at frequencies between 1 and 5 Hz. This is achieved by adapting the CREMV to enable rotational frequency and the eccentricity (205, 206) of the masses relative to their rotation axes (203-204) to be varied independently and simultaneously, and by designing the CREMV such that the radius of rotation of the center of mass of each rotating mass is on the order of 50 cm or more.

Abstract: Method and apparatus for producing a bubble curtain with a diversity of bubble diameters for purposes such as modifying the characteristics of a seismic source used in marine seismic surveys. Bubble generating elements are used that combine porous wall material with discrete holes (91) to create a curtain of diverse-sized bubbles (92).

Abstract: Method and apparatus for producing a bubble curtain with a diversity of bubble diameters for purposes such as modifying the characteristics of a seismic source used in marine seismic surveys. Bubble generating elements are used that combine porous wall material with discrete holes (91) to create a curtain of diverse-sized bubbles (92).

Abstract: Method and apparatus for producing a bubble curtain with a diversity of bubble diameters for purposes such as suppressing surface-related multiple reflections in marine seismic surveys. Bubble generating elements are used that combine porous wall material with discrete holes.