Quantification of Reservoir Pressure-sensitivity Using Multiple Monitor 4D Seismic Data

Key to quantitative interpretation of 4D seismic data for the separation of pressure and saturation effects is accurate knowledge of their individual contributions to the 4D seismic signatures. Currently, pressure sensitivity is calibrated using laboratory measurements on core plugs that have limited applicability to the in-situ field-scale reservoir response. A complementary technique for estimating pressure sensitivity is to compare seismic and pressure measurements. This is possible in selected areas around and away from wells where pressure variations contribute predominantly to the 4D signatures. Multiple monitor 4D seismic data are utilised to sample these areas as a function of field production time. The technique is applied to seismic amplitudes across a variety of producing North Sea clastic reservoirs. The results indicate that pressure sensitivity varies according to the geology of each reservoir. Also, estimates around some water injectors appear to show elevated sensitivity, suggesting the presence of induced fractures.