Abstract: Method of vertical seismic profiling in drilling operations utilizing the drill bit for a source of seismic energy without any break in drilling operations. The noise of the drill bit and reflections of the noise in the formation are recorded with the aid of a geometrically extended array of receivers which are provided in a predetermined matrix group. The received signals are analyzed according to velocity and migration principles per se on the basis of differences in reception times, by which the noise signature of the drill bit can be determined at any desired location during drilling operations and extracted from the traces. The remaining received signal frequencies and signal amplitudes are analyzed in relation to their deviation in time, the signals being grouped according to time differences corresponding to focusing on certain areas in the formation.

Abstract: Disclosed is an underwater seismic energy source which includes a plurality of airguns. Each of the airguns has substantially the same size, weight and external configuration, but the internal capacities are configured such that when the guns are fired the primary pulses interfere constructively and the bubble pulses interfere destructively. Each of the airguns is connected in the same way to an individual tow line, each having the same length. When the airguns are towed, they are maintain substantially the same depth, even without flotation devices such as Norwegian buoys or rigid floats.