1. BHP Billiton, Saskatoon, Saskatchewan S7K 1L3, Canada.(corresponding author).
2. The University of Oklahoma, School of Geology and Geophysics, Norman, Oklahoma OK 73019, USA..
3. SEG, Tulsa, Oklahoma OK 74137, USA..
4. Saudi Aramco, Exploration Application Services Department, Dhahran 31311, Saudi Arabia..