Low-frequency attenuation measurements of fluids

Pore fluids significantly affect the elastic responses of rocks. Rock-physics models can be used to predict how pore fluids affect the elastic responses of fully or partially saturated rocks. Thus, to identify fluids in the subsurface, knowing the anelastic properties of such fluids, such as attenuation, is useful. In addition, new technologies to assess and monitor hydrocarbon exploration rely on the precise determination of the anelastic properties of hydraulic fracturing fluids. Moreover, the anelastic properties of fluids depend on the frequency of the wave propagating through the fluid. Methodologies to measure high-frequency anelastic properties of fluids have been widely reported. What have not been established are methodologies to measure the low-frequency anelastic properties and attenuation of fluids in a laboratory setting, aside from shear viscosity. Using the low-frequency properties and attenuation, rather than the already known high-frequency properties of pore fluids, will provide more accurate estimates for rock physics models and seismic data. To address this situation, a laboratory machine has been designed, built, and calibrated to measure the low-frequency attenuation and bulk modulus of fluids at frequencies from 0.1 to 10 Hz. Deionized water and aqueous guar gum solutions have been tested. Results for measurements of attenuation and bulk modulus of water agree with the literature. Measurements of guar gum solutions show that attenuation is greater than 0.01 with higher concentration samples having higher attenuation. This might be explained by energy being lost during the breakup of weak and strong bonds in the guar gum polymer chains. A higher concentration provides more bonds to break up which leads to more energy being lost which increases attenuation. The present study will help improve seismic methods and rock physics models by incorporating low-frequency attenuation values of fluids.