Amoco Corporation

Bp Corporation North America Inc.

Richard L Crider

Leon A Thomsen

Gerard Joseph Beaudoin

The instant invention is generally directed toward methods of using an AVO-type analysis on unstacked seismic data to identify subsurface exploration prospects. More particularly, a new method of identiflying and displaying converted mode seismic reflections is provided that has significant advantages over that in the prior art. Additionally, the instant invention can be used to attenuate or eliminate seismic reflections such as multiples that are not flattened by conventional velocity analysis. Further, a method is disclosed that provides for identification and display of only those seismic reflections deemed consistent with the usual or expected AVO behavior. Finally, another aspect of the instant invention involves the use of statistical goodness of fit measures, such as the Coefficient of Determination, to create a seismic display that is indicative of the degree to which each time slice in a gather conforms to a proposed AVO model.

Selection of seismic modes through amplitude characteristics

Time-invariant multichannel seismic data filters are applied to seismic data traces for rejecting coherent noise signals within a time-space window. In one embodiment, these filters are applied for rejecting all signals having the same trace-to-trace slopes as the coherent noise signal. Segments of the filtered traces that are within the time-space window are added to corresponding segments of unfiltered traces outside of the time window for producing reconstituted time-variantly filtered traces. In another embodiment, these filters are applied for rejecting the coherent noise signals and passing all other signals within the time-space window and passing all signals outside of the window for producing time-variantly filtered traces.

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Houston, TX, United States of America

Richard L Crider