Xu and White Revisited

In this paper we show that a single aspect ratio applied to the total porosity of a sand-clay mixture can accurately model both P- and S-sonic data. We also show that the variation of this optimal aspect ratio can be predicted from the petrophysical properties of the rocks, whilst keeping the effective elastic properties of the minerals constant over large geological intervals. The use of one variable aspect ratio applied to the total porosity provides a much better fit to the data than using a single aspect ratio for each mineral.