1. Formerly Princeton University, Department of Geosciences, Princeton, New Jersey, USA; presently Saudi Aramco, Dhahran, Saudi Arabia. (corresponding author)
2. DNO ASA, Oslo, Norway.
3. Princeton University, Department of Geosciences, Princeton, New Jersey, USA.
4. Princeton University, Department of Geosciences, Princeton, New Jersey, USA and Princeton University, Program in Applied and Computational Mathematics, Princeton, New Jersey, USA.