1. SINTEFDepartment of Petroleum S.P. Andersens veg 15b, 7031 Trondheim Norway
2. Norwegian University of Science and TechnologyDepartment of Geoscience and Petroleum S. P. Andersens veg 15a, 7031 Trondheim Norway
3. Present address: AkerBP Munkegata 26, 7011 Trondheim Norway