Abstract: A method of processing geophysical signals obtained by monitoring the response of the earth to an source using a plurality of receivers is described including the evaluation of sums or integrals of functions of weighted signal values over a one or multidimensional domain such that the domain is split into a plurality of simplices and the signal values are interpolated across the simplices using a non-linear approximation of the function, the approximation including signals and gradients of the signals, and the evaluated sums or integrals are used to obtain a representation of characteristics of the earth.

Abstract: A method and related apparatus are described for generating acoustic signals for use in a vibratory seismic survey, including at least two different sweep signals for the control of at least two different types of vibrators; and matching the phases of the different sweep signals at a transition frequency from one sweep signal to another.

Abstract: An acoustic emitter for coupling in series in a marine seismic streamer is provided with an annular housing and an annular piezoelectric emitting element positioned coaxially within the housing. This form of construction permits the electrical or electro-optical transmission line which normally runs along the axis of the streamer to pass through the center of the emitting element, while also permitting the emitter to be spooled with the streamer.

Abstract: The invention provides a method of processing seismic data acquired using a seismic source array that emits, in use, a seismic wavefield having a frequency spectrum that does not contain a source ghost at a non-zero frequency within the seismic bandwidth. This eliminates source-side ghost reflections. The method further comprises processing the acquired seismic data thereby to attenuate the effect of ghost reflections in the seismic data, and this eliminates receiver-side ghost reflections.

Abstract: A method and system for performing a marine seismic survey is described, including towing at least one seismic streamer comprising a plurality of hydrophones distributed at average intervals of not more than 625 cm therealong in the water over the area to be surveyed; directing acoustic signals down through the water and into the earth beneath; receiving with the hydrophones seismic signals reflected from strata in the earth beneath the water; digitizing the output of each hydrophone separately; and filtering the output to reduce the noise present in the output and to generate a signal with a reduced noise content wherein the filtering process uses as further input the digitized output of at least one nearby hydrophone. The filtering is applied to single sensor recording prior to group-forming and thus able to detect and reduce coherent noise with a coherency length of 20 meters or less. It reduces noise such as streamer or bulge noise.

Abstract: A method is provided for analyzing received seismic signals which are received from a plurality of seismic sensors in response to operation of an acoustic source during a marine seismic survey. The seismic sensors are located at different offsets from the acoustic source. The method comprises the steps of selecting a time window within a particular seismic signal which frames a relatively well-defined event represented in the signal. The particular seismic signal is received from a particular seismic sensor. The method further comprises determining a receiver ghost notch frequency from an amplitude/frequency spectrum of the seismic signal in the window and deriving from the receiver ghost notch frequency an estimate of a height of a water column above the particular seismic sensor which generated said particular seismic signal.

Abstract: A method for correcting seismic data for periodic distortion introduced by acquisition parameters by filtering modified unitary transform data. A vertical transform is applied to seismic data to obtain frequency-space seismic data. These data are decomposed into an amplitude component and a phase response component. The phase response component is saved for the inverse process. A horizontal transform is applied to the amplitude component of the F-X data to obtain modified transform data. Because this transformation is performed in the X direction, it is here also referred to as the horizontal forward Fourier transformation. A K filter based on the period of the energy to be suppressed or eliminated is applied to this F-K data. The K filter may be, for example, a notch filter or any suitable filter. The data are then inverted to obtain T-X data with distortion suppressed or eliminate.