NIGHTMARE MULTIPLES - A STEP TOWARDS A SOLUTION

摘要

For several years UNOCAL Indonesia has aggressively pursued the suppression of very strong multiples obscuring key oil and gas pay zones in its Kutei Basin fields in Indonesia. The rough water bottom and shallow hydrate reflectors give rise to strong out-of-plane energy in the multiple wavefield that often arrives simultaneously from several azimuths. The geometry and reflectivity of the hydrates vary rapidly in space generating a large amount of diffracted energy in the multiple wavefield. Numerous multiple-suppression techniques such as wave equation, high resolution radon, fk, and pattern matching have been extensively tested without significant improvements in the resulting seismic images. Here we report the results of a processing sequence that was successful in dramatically improving the deep image for frequencies up to 13 hertz in the most multiple-ridden field, Ranggas. The processing sequence included radon filter followed by a depth-model-based demultiple technique (Heinze et al., 2001).