Diffraction imaging – a tool to reduce exploration and development risk

When evaluating exploration prospects, discoveries or a field under development it is essential to build an accurate structural framework at an appropriate scale. Detailed understanding of the fault network enables reservoir compartmentalisation risk to be better quantified at the exploration prospect stage and informs well placement optimisation in the exploration, appraisal and development phase. This paper presents a method for maximising fault information from depth migrated narrow azimuth seismic data. The faults are imaged in the depth domain by separating the diffracted component from the total migrated wavefield. We show that diffraction imaging gives higher resolution fault definition than either a conventional seismic reflectivity volume or conventional post-stack fault enhancement attributes. We also show that diffraction volumes can be further processed to generate attribute volumes with fault definition sharp enough to pick with automatic fault detection algorithms, producing a highly-detailed fault network that can augment manual fault interpretation products and be incorporated into the structural framework. Diffraction imaging is a technique for imaging small scale subsurface geological objects and discontinuities, such as faults, unconformities and karsts using the diffracted component of the total recorded wavefield.