Seismic imaging of a thin unconventional reservoir in highly attenuating media: the case of the Macasty Formation, Anticosti Island, Canada

摘要

Seismic wave propagation through the subsurface is characterized by a loss of high frequency energy desired for high-resolution imaging at depth. This means that the size of geological features that can be resolved increases with depth. In this context, exploration of thin-layered unconventional reservoirs represents a significant challenge for seismic imaging. Here the case of the Macasty Formation, a thin-layered shale reservoir included in a highly attenuating limestone-dominated Silurian-Ordovician succession, is discussed. To retrieve high frequency energy, Q-phase compensation, zero-phase deconvolution and a 90°-phase rotation followed by the application of a Butterworth filter are used. Results provide an amplitude spectrum that is flatter and broader compared to the original data. New imaging resolves internal high amplitude reflections within the reservoir that are correlative to higher TOC values of the pay-zone.