A Methodology to Integrate Magnetic Resonance and Acoustic Measurements for Reservoir Characterization

Compressional waves in heterogeneous permeable media suffer attenuation fiom both scattering and induced pore scale flow of the viscous saturating fluid. Stochastic medium theories are used to describe scattering on multiple length scales, and are validated by numerical examples using a dual length scale sedimentary sequence taken from a producing oil reservoir. The highly variable permeability in this sequence also affects the wave attenuation due to pore flow. The numericalIy observed squirt flow attenuation occurs at characteristic frequencies controlled by the individual permeability of each member instead of the formation average permeability. Depending on the viscosity of the saturating fluid, the magnitude of the flow-based attenuation can dominate or be dominated by the scattering attenuation at typical sonic logging frequencies (-1 0 kI3.z). For the moderate attenuating mechanisms considered, the overall attenuation is well approximated by the sum of the scattering attenuation from stochastic medium theory and the volume weighted average of the intrinsic attenuations of the sequence member rocks.