Effects of microporosity on sonic velocity in carbonate rocks

The elastic moduli of a rock are affected by three main factors: pore fluid, rock framework, and pore space. In carbonate rocks, the latter two factors are a function of the depositional environment and the diagenetic history. Cementation, recrystallization, and dissolution processes can change the mineralogy and texture of the original framework and thereby alter the original grain-to-grain contacts and/or occlude pore space. Dissolution processes can enlarge interparticle pore space or dissolve grains entirely, thereby increasing porosity. These diagenetic alterations and associated changes in the rock frame and pore structure result in a wide velocity range at a given porosity.