What you can see is what you can get: Seismic attenuation and imaging

Intrinsic attenuation of seismic waves (amplitude loss) in the earth is related to the fluid content and fluid mobility within pore spaces.  Inverting seismic images to give us this information would provide several quantum steps forward in our ability to understand how fluids move in the subsurface and to predict how fluid movements can be predicted or controlled for applied purposes like hydrocarbon production, CO₂ sequestration or contaminant transport. Dr. Kurt Nihei at colleagues at Lawrence Berkeley National Laboratory  has made some of the first laboratory images of seismic intrinsic attenuation.  Seismic images today are a complex mix of energy returns along many pathways through the earth, with scattered, reflected and refracted energy as well as amplitude loss from the intrinsic attenuation related to fluids.

Velocity (left) and quality factor (right) from viscoacoustic inversion of laboratory data.

Nihei's project investigated the acoustic imaging problem of targeting acrylic rods within a water tank.  He illuminated the tank with broadband acoustic energy from 16 sources and recorded the signals with 31 receivers. The data from the water tank became the test case for modeling of the amplitude modification for attenuated waves.  The acoustic wave propagation through the water, through the acrylic rods, and reflected from the rods was numerically modeled with a finite difference viscoelastic algorithm, and matched to the observed acoustic signal transmission.

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