ABSTRACT
Acoustic logging includes those techniques that use a transducer to transmit acoustic energy through the fluid in the well, into surrounding elastic materials, and back to an acoustic receiver in the probe. Different types of acoustic logs are based on the frequencies used, the way the signal is recorded, and the purpose of the log. All acoustic logs require fluid in the well to couple the signal to the surrounding rocks. Two types are described here: acoustic velocity and acoustic waveform. Acoustic-televiewer logs are described under borehole imaging logs. Acoustic velocity in porous media is dependent on such lithologic parameters as porosity; type of matrix; density; and size, distribution, and type of grains and pore spaces. It also is related to the cementation and the elastic properties of the interstitial fluids. Hearst and Nelson present a broad discussion on acoustic logging and the propagation of waves in geologic media.
