Abstract: Apparatus for forming a downwardly directed beam of acoustic wave energy in a body of water, comprising a source of acoustic wave energy such as a water gun, supported at a selected depth in the body of water. Means are provided above and around the source in the form of a series of concentric circular tubes of selected diameters and spacing so that the enveloping surface is a paraboloid. A large number of small perforations are spaced along these horizontal tubes through which compressed gas, which is supplied to the tubes, can escape and form spaced rising columns with small gas bubbles in the volume of water above the paraboloid. The highly reflecting contact surface between the water within the paraboloid and the gas-water mixture above the paraboloid causes downward reflection of seismic energy from the source in the form of plain waves of seismic energy.

Abstract: A moving seismic source system for the use in water-covered areas comprising a conventional source and streamer cable means with multiple receiver, and additionally includes between the source and receivers a volume of the body of water containing a small percentage of free gas to form a gas-water mixture. The volume of gas-water mixture is of select size and shape to form an interface with the gas-free water to form, for example, a paraboloid which acts to reflect and attenuate acoustic waves that impinge on the interface and so minimizes extraneous seismic noise.