Mechanical facies, which represent the rocks' dynamic and mechanical properties, can be used to characterize and subdivide reservoir formations at the borehole and in areas between wells. For example, the mechanical facies of the Travis Peak-Cotton Valley sequence of east Texas and western Louisiana can be used to distinguish and accurately map poor reservoir calcite-cemented zones. Mechanical facies are derived from acoustic logs where both compressional and shear wave velocities are obtained.

The advantages of using mechanical facies for reservoir characterization, classification, and subdivision are:

1. Mechanical facies are a quantification of a rock's in-situ physical properties and can reflect the dynamic characteristics of the reservoir.

2. Mechanical facies may provide useful information away from the borehole by combining acoustic logging and tomographic survey data to classify and characterize reservoir zones laterally as well as vertically.

3. Mechanical facies can be used for well-to-well correlation.

4. Mechanical facies provide a continuous record and can be obtained in uncased or, under proper conditions, cased wells.

The versatility of mechanical facies for reservoir description and characterization is illustrated by several examples from diverse areas and for varying lithology.