Image Number 4 for United States Patent #4888740.
A method for acoustically investigating characteristics of formations penetrated by a borehole such as fractures by taking differential Stoneley wave acoustic energy measurements between pairs of receivers of an array of receivers carried by a logging tool. The receivers of each pair all have the same spacing. The energy is that detected by the receivers in response to acoustic pulses generated by a transmitter spaced from the receivers on the tool. The differential energy measurements are stacked to obtain a stacked differential energy log.