Acoustic emissions during deformation of sandstone with fluids

We experimentally investigate the effect of the pore fluid on AE in four sandstone plugs cored from a homogeneous slab. These plugs were fully saturated with brine, mineral oil, and hexane, while one of them remained dry. AE level was highest in the hexane-saturated sample, smaller in the oil-saturated sample, and even smaller in the brine-saturated sample. It was even smaller in the dry sample. It appears that in the liquid-saturated plugs, the AE level is monotonically related to the acoustic impedance of the pore fluid – the smaller the impedance the higher the AE. It does not appear to be related to the viscosity of the pore fluid.