values and a wide range of real materials. Because of the form of its frequency-dependence and the relatively low center source frequency used in well logging surveys, the viscous coupling coefficient can be approximated by the value in the cylindrical duct geometry.
ReferencesBerryman, J. G., 1980, Confirmation of Biot' s theory: Appl. Phys. Lett., 37, 382-385. Biot, M. A., 1956, Theory of propagation of elastic waves in a fluid saturated porous solid: J. Acoust. Sot. Am., 28, 168-191. Schmitt, D. P., Bouchon, M., and Bonnet, G., 1985, Full wave synthetic acoustic logs in saturated porous media, Part 1, Theory and simple configuration: Presented at the 54th Annual SEG Meeting, Atlanta. FrameToday more than ever, a lot is expected from full waveform acoustic logging to enhance the knowledge of underground fluid reservoirs. This study is meant to apply new interpretation schemes to data from fractured crystalline formations. Qualitative analysis of acoustic amplitude, traveltime, and discontinuity-generated (DG) waves is made with reference to conventional logs. It shows that amplitudes of compressional, shear, and Stoneley waves discriminate zones containing fluid, whereas traveltime of compressional and shear waves, and DG waves, are better fit for precise lithologic identification of clean rock and fractured zones. A newly developed theory based on an energy transfer mechanism between borehole fluid and formation fluid relates the amplitude of Stoneley waves to fracture permeability. This theory is applied in a quantitative analysis of the data, to give estimates of fracture permeabilities.
Introduction and tool description
