1. Technical Researcher, Dept. of Geosciences and Geological and Petroleum Engineering, Missouri Univ. of Science and Technology, Rolla, MO 65409.
2. Professor and K.F. Hasselmann Chair in Geological Engineering, Dept. of Geosciences and Geological and Petroleum Engineering, Missouri Univ. of Science and Technology, Rolla, MO 65409 (corresponding author).