STATISTICAL AUTOMATIC STATICS ANALYSIS

Abstract

From theoretical considerations and extensive experience, we show that proper weathering statics can be computed by use of a systematic analysis of correlation statistics. Time jitter on individual traces due to weathering variations, variations in shot depth, and trace reversals can be determined and corrected for in the presence of interference due to noise, dip, and improper normal‐moveout corrections. Four independent sets of statistics, requiring two time windows for shot‐oriented data and two time windows for receiver‐oriented data, are used to determine static corrections at the shot and at the receiver. To determine shot statics, we correlate pairs of traces from the same receivers and consecutive shots. Pairs of traces from consecutive receivers and the same shots are correlated to determine receiver statics. These two sets of correlation functions are viewed statistically to determine the two subsets of functions needed for the ensuing analysis. The functions remaining after rejection of those deviating greatly from the average values are summed in groups by receiver and by shot order. The resultant peaks yield two sets of differential statics. A cumulative total of the differential statics is computed. Subtraction of the low wavenumber part of the cumulative total, which is the dip, from the cumulative total yields residual shot and receiver weathering statics.