A New Approach to Reducing Multiple Leakage on Time Lapse Datasets

The standard processing solution in time-lapse analysis to the problem of non-repeatable noise sources, both coherent and random, is to perform the best denoise on all of the vintages independently. For this purpose, 4D QC measures and, of course, inspections of the seismic 4D differences are used to find the optimum parameter solution. This is currently also best practice in the removal of multiple energy, as there are many reasons for multiples to be non-repeatable, in particular changes in the source and receiver locations, changes in the water-layer and variations in the acquisition wavelet. Finding the optimal multiple subtraction operators on each vintage so as to obtain the least leakage of multiple energy on the 4D difference is notoriously difficult. In this paper we introduce a novel inversion scheme which designs shaping operators for the optimum adaptation of the multiple models to the individual vintages whilst simultaneously optimizing the subtractions for minimum leakage on the 4D difference.