ENHANCING FAULT INTERPRETATION THROUGH BROADBAND PROCESSING AND DIFFRACTION IMAGING: THE FIRST AND SUCCESSFUL EXPERIENCE FROM MADURA OFFSHORE AREA

摘要

Accurate interpretation of faults is of great importance for exploration and development studies in oil and gas fields. In this paper, we share our successful experience of enhancing fault interpretation through state of the art broadband seismic processing applied to a 2005 dataset from offshore Southeast Madura. Previous "legacy'" processing of the data shows significant dimming of reflectors due to strong shallow gas absorption. This severely complicates the fault interpretation, to the extent of creating an ambiguous fault system model. We show how broadband deghosting and demultiple increases the bandwidth and yields better fault imaging. Using the broadband processed data, we apply diffraction imaging to further improve the fault interpretation reliability. A plane wave destructor separates diffraction and reflection energy in order to migrate the diffraction and reflection contributions separately. Recombining the reflection , and diffraction migrations provides additional improvement to the final image. Fault interpretation on the diffraction-enhanced final image results in a better defined and more continuous fault system from the shallow part down to the reservoir level. To evaluate the image uplift, we perform edge-detection based fault extraction and enhancement to the legacy and broadband processed data. The fault system from the broadband processing shows significant improvement over the legacy data. Furthermore, diffraction imaging yields additional enhancement to the fault network extraction, thereby significantly reducing the uncertainty and ambiguity of the fault interpretation for the field development.