Ultrasonic frequency difference generation to characterize fluids in saturated Berea sandstone

The use of nonlinear acoustics to characterize fluids in porous media is presented. The acoustic nonlinearity in sandstone is affected by the presence of water or oil. This difference in properties that affect the sound propagation through such media can be used to determine whether a piece of sandstone contains water or oil. Traditional methods of characterizing porous media usually rely on the transmission or reflection of a single ultrasonic probe pulse. The technique presented in this paper uses a method of generating a probe pulse inside the porous medium from the interaction of two pulses. Information about the medium is then contained in the propagation of this probe signal back to a receiver. The main advantage of this approach is that it allows implementation of this technique inside a borehole for characterizing the porous media outside