Westerngeco L.l.p.

Rainer Moerig

Frederick James Barr

Gary Arthur Sitton

David Lee Nyland

John James Sallas

The present invention provides a method for harmonic noise attenuation in correlated sweep data in seismic exploration. The method includes forming a plurality of correlation data subsets using a plurality of sweep data sets and a correlation reference sequence. The method further includes estimating a noise level in a correlation data set using the correlation data subsets and subtracting the estimated noise level from the correlation data set.

Method of harmonic noise attenuation in correlated sweep data

This invention relates to improved methods to generate shaped sweeps, and for the acquisition of vibroseis data with a shaped pilot sweep.

Vibrator sweep shaping method

A method of seismic surveying using one or more vibrational seismic energy sources activated by sweep signals. The highest order harmonic that has sufficient strength to cause significant harmonic distortion of a sweep segment is determined. A number of sweep segments in excess of the number of sources is selected. Initial phase angles are selected for each sweep segment of each seismic energy source so that substantially all harmonics up to and including the highest order harmonic are suppressed. Using cascaded sweeps, seismic data are acquired and processed to substantially attenuate harmonics upto the selected order.

Method of using cascaded sweeps for source coding and harmonic cancellation

The present invention is a method for processing seismic data comprising acquiring seismic data using a sweep sequence including a plurality of cascaded sweep segments. The seismic data include a plurality of data segments and a listen time. The listen is combined with an initial data segment. The seismic data segments are phase shifted to a phase of a target data segment to be denoised (i.e. removal of ambient, harmonic and coherent noise). A difference between the target data segment and the remaining data segments is determined. If the determined difference exceeds a predetermined threshold, data in the target data segment is replaced with data derived from the remaining data segments. The data segments may be stacked to form a new target data segment. The listen time is extracted from the initial data segment.

Method of noise removal for cascaded sweep data

A speaker system is used in conjunction with a surface seismic source that may be vibratory or impulsive. A speaker system having one or more speakers produces a sound signal that propagates primarily through the air and is received by microphones near the seismic spread. A transfer function between the microphones and the geophones in the seismic spread is determined from the speaker signal and used to filter out the airborne noise produced by the surface seismic source. The source may include or more vibrators that may be operated in a predetermined phase-relationship. The noise-attenuated signals may then be processed to separate out the contributions of the individual sources. Another embodiment of the invention uses accelerometer measurements of the reaction mass or the base plate of the vibrators or combination of the two measurements to invert the noise-attenuated signals.

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Houston, TX, United States of America

Rainer Moerig