Fluid mobility in reservoir rocks from integrated VSP and openhole data

Abstract

SUMMARYIn this study, we first estimate seismic velocity and attenuation dispersion from a comprehensive zero-offset vertical seismic profile (VSP) data acquired in China. These results, combined with openhole data acquired at the same location, provide experimental evidence that the seismic attenuation in rocks is dominated by a fluid-flow mechanism. The loss mechanism due to multiple scattering is found to be negligible. This implies that extraction of fluid mobility (permeability to viscosity ratio) in reservoir rocks using low frequency (10 to 150 Hz) seismic data should be possible. We present a methodology, based on poroelastic inversion using a rotated coordinate system and simulated annealing, to extract fluid mobility from combined VSP and openhole data. Finally, we compare layerspecific fluid mobility values, obtained using this approach, with independent fluid mobility measurements and estimates based on wireline openhole data.