P rsu H d J. For years, geophysicists have noticed low-frequency seismic a 1 K m d r a 1 2 i v r o e

10.1190/1.3207863nomalies associated with hydrocarbon reservoirs Taner et al., 979, and this topic still maintains the interest of many van der olk et al., 2001; Castagna et al., 2003; Korneev et al., 2004; Chap-an et al., 2006. Although the mechanisms that cause frequency-ependent anomalies have not been defined clearly, many authors eport that hydrocarbon-saturated reservoir zones often show anom-lously high values of attenuation Castagna et al., 1993; Klimentos, 995; Dasgupta and Clark, 1998; Dasios et al., 2001; Rapoport et al., numerous gas bubbles in water-saturated porous media, or thinly layered porous media in which water-saturated layers alternate with gas-saturated layers, to explain high attenuation in the seismic fre-quency band. This model is known commonly as White’s model. Dutta and Ode 1979a, 1979b and Dutta and Seriff 1979 numer-ically calculated the accuracy of White’s patchy-saturation model. They find that the gas-bubble model and the thinly layered model ar