The Barnett and Eagle Ford shale formations are two of the most actively drilled shale plays in the U.S. The petrophysical properties of these organic-rich shales are essential to assess their potential to be developed economically. In this paper, we present a systematic laboratory methodology we have used to characterize and compare the petrophysical properties of Barnett and Eagle Ford shale formations.

Preserved core samples from these two formations were used for the characterization. Petrophysical properties measured include the native water activity of the shales, the swelling induced by different fluids in directions perpendicular and parallel to bedding, Brinell hardness, and P-wave and S-wave velocities. Brinell hardness and wave velocities were compared before and after shales came into contact with water-based fluids to study the effects of shale-fluid interactions on these properties. A unique 2-D swelling indicator in our lab allowed us to measure swelling in two directions simultaneously. A pressure transient technique was used to determine the permeability of water-based fluids flowing through the shale samples.

Our results showed a good correlation between changes in weight, swelling, Brinell hardness, and sonic velocity measurements. Anisotropic swelling was observed in directions parallel and perpendicular to the bedding planes. Sonic velocities were converted to dynamic elastic moduli. Our results also demonstrated the uniqueness of individual shale plays in terms of petrophysical properties.