On White’s model of attenuation in rocks with partial gas saturation

Abstract

In two important papers, J. E. White and coauthors (White, 1975; White et al, 1976) have given an approximate theory for the calculation of attenuation and dispersion of compressional seismic waves in porous rocks filled mostly with brine but containing gas-filled regions. Modifications of White' s formulas for kE and Q in the case of gas-filled spheres brings the results into good agreement with the more exact calculations of Dutta and Ode (1979 a, b, this issue), who used Biot' s theory for porous solids. In particular, the modified formulas give the expected Gassmann-Wood velocity at very low frequencies.Inclusion of the finite gas compressibility in numerical calculations for gas-filled spheres shows an interesting maximum of the attenuation at low gas saturations which is not seen if the gas is ignored.A comparison of the attenuation calculated for the same rock and fluids but for three different geometries of the gas-filled regions suggests that the configuration of the gas-filled zones does not hav*e an important effect on the magnitude of the attenuation.

Frequency-dependent attenuation as a potential indicator of oil saturation

“…(A8)) is dominated by the absolute thickness of the layers and the flow parameters, i.e., viscosity and permeability. For better understanding the dependence of 1 / Q of the interlayer-flow model on the basic petrophysical parameters, some approximations may be used, which are mathematically much simpler than the full solution, such as approximations for the value of f tr (Dutta and Seriff, 1979) and for the maximum value of attenuation, 1/Q min (Quintal et al, 2009(Quintal et al, , 2011a. The approximations derived by Dutta and Seriff (1979) and Quintal et al (2009) are limited to media with a homogeneous solid frame and layers characterized only by different fluid saturation, with one fluid much more compressible than the other.…”

Constraining the reservoir model of an injected CO2 plume with crosswell CASSM at the Frio-II brine pilot

“…This theoretical model, initially proposed by White (1975), includes the corrections made by Dutta and Seriff (1979), for the prediction and interpretation of seismic property changes due to partial CO 2 saturation. White's model assumes a homogeneous rock frame with spherical patches of dimension r saturated with a second fluid phase, in our case supercritical CO 2 .…”

One‐dimensional random patchy saturation model for velocity and attenuation in porous rocks

“…This means that at intermediate frequencies the partially saturated medium exhibits P-wave velocity dispersion and attenuation. We are aware of only few models proposed to model frequencydependent effects of patchy saturation, including the periodic flat-slab model (Norris, 1993) and the spherical-shell model (White, 1975;Dutta and Seriff, 1979). Johnson (2001) developed a more general theory for elastic properties of rock containing regular distribution of pockets of two fluids assuming that the bulk modulus must obey Gassmann theory at low and high frequencies and must also obey causality constraints.…”