| Popis: |
This chapter focuses on the characterization and modeling of argillaceous porous medium by compressional and the shear acoustic waves. The prediction of effective porosity and elastic moduli in mixed phases depends on volume fractions and the elastic modulus of each phase as well as their geometrical combination. With volume fractions specification, it is only possible to predict the mixed upper and lower elastic moduli bounds. The results showed that the clay compaction evolution and the water drainage cause density increase. It is observed that clay is initially put in suspension in water and then arranges itself progressively to raise a laminated structure. The ultimate stage of compaction tends to form a mineral block of a much reduced porosity, in which anisotropy tends to disappear. Taking into account of geometrical structure, and Reuss and Voigt formulations, it is possible to express clays bulk and shear moduli. To use the good values for mineral elastic moduli, it is advisable to have a good reliability about the clay mineralogy for a given depth. Clay mineralogy determination could be done with two methods—X-Ray diffraction on plugs, and gamma ray spectroscopy. |
