Accurate reservoir property prediction or structural interpretation can be highly dependent on the flatness of events on seismic gathers. In many instances, gathers exhibit complex residual moveout effects that if left untreated can degrade the structural image or introduce spurious effects into subsequent AVO/AVA inversion. The result can be inaccurate structural interpretation, poor matches between surface seismic and well data, or misleading reservoir property estimation.
A number of conventional approaches exist to help align events as preconditioning for inversion or stack; however, all have significant limitations. An approach is needed that can provide high vertical and lateral resolution while maintaining volumetric consistency on a local scale. It should be robust against potential cycle skipping in areas where the moveout distortions are large, and be capable of comprehending amplitude and phase changes with angle (or offset) even in the proximity of strong reflection events.
REVEAL is a new approach offered by WesternGeco to provide enhanced gather flattening to any type of seismic data, and is enabled by the Schlumberger proprietary non-rigid matching technique.
REVEAL estimates locally varying, locally smooth, time shifts across a seismic gather exhibiting residual moveout. It is spatially "aware", in contrast to other methods that only use individual pairs of traces, and hence, have no concept of local consistency or smoothness.
REVEAL can be applied late in the processing sequence after all other signal enhancement steps have been applied, such as wavelet shaping across offsets/angles. The process delivers fully flattened gathers across a wide range of angles or offsets. The result? Improved confidence in structural interpretation and more reliable AVO analysis and inversion products.
REVEAL is also applicable in enhancing time-lapse (4D) analysis, and now forms a key component in many of our inversion-ready and 4D-ready workflows.