| 摘要 |
1482577 Seismic exploration SOC NATIONALE DES PETROLES D'AQUITAINE 10 Sept 1974 [14 Sept 1973 27 Aug 1974] 39439/74. Heading G1G A multi-trace seismic record is obtained by a field procedure in which the source and receiver spacings are such that the lateral interval between consecutive depth points is not greater than the inverse of twice the maximum wave number of seismic waves to be recorded. A spatial-frequency, i.e. wave-number, k, analysis of the record is then made to identify unwanted, e.g. coherent, noise and the record is filtered to remove those spatialfrequencies associated with the noise. In embodiments described, a source at the point of intersection of two rows of receivers, or vice versa, is used to provide multiple coverage of common depth points (CDP). A velocity analysis of the CDP traces is made after static corrections have been applied; then dynamic corrections are applied using the velocity information. The spatialfrequency analysis is made by defining timewindows across the traces, in each time-window sampling the trace amplitude to obtain an amplitude-versus-depth point function, and determining the spatial-frequency spectre of the various functions. Based on this analysis, k, filtering alone or together with temporal-frequency (f) filtering is applied to the traces to remove noise. The filtered traces are then stacked to form a seismic section. A separate section showing noise only may be recorded by use of complementary filtering. In alternative embodiments the order of the steps of applying corrections, filtering and stacking is different. The filtering can also be used to remove unwanted refraction events from the traces. |
