Constraining uncertainty in interpretation of seismically imaged clinoforms in deltaic reservoirs, Troll field, Norwegian North Sea: Insights from forward seismic models of outcrop analogs Nicholas E. Holgate, Gary J. Hampson, Christopher A.-L. Jackson, and Steen A. Petersen ABSTRACT Forward seismic modeling of outcrop analogs has been used to characterize the seismic expression of clinoforms in different del- taic depositional environments, and thus constrain uncertainty in interpretation of intra-reservoir clinoforms imaged in seismic data from the Troll field, Norwegian North Sea. Three outcrop analogs from the Cretaceous Western Interior seaway, United States, were studied to quantify the geometry, distribution, and lithologic char- acter of clinoforms in fluvial-dominated and mixed-influence del- taic deposits. Outcrop-derived geometric data were calibrated to sedimentological and petrophysical data from the Krossfjord and Fensfjord Formations in the Troll field, and then used to create a suite of forward seismic models for comparison with real seismic reflection data from the Troll field. Clinoforms were imaged in the forward seismic models in which they were (1) spaced wider than the tuning thickness (>10 m [>33 ft]); (2) marked by pro- nounced interfingering of facies associations with different acous- tic properties; and/or (3) lined by relatively thick (>50 cm [>20 in.]) carbonate-cemented layers. However, where clino- thems are thinner than the vertical resolution limit of seismic data, destructive interference occurred creating misleading geometrical relationships. Furthermore, our ability to image clinoforms is de- pendent on (1) the frequency of the seismic wavelet; (2) the Copyright ©2014. The American Association of Petroleum Geologists. All rights reserved. Manuscript received August 23, 2013; provisional acceptance January 10, 2014; revised manuscript received February 18, 2014; final acceptance May 28, 2014. DOI: 10.1306/05281413152 AUTHORS Nicholas E. Holgate ∼ Imperial College, Basins Research Group (BRG), Department of Earth Science & Engineering, Prince Consort Road, London, SW7 2BP, England, United Kingdom; n.holgate09@imperial.ac.uk Nicholas Holgate is currently working as an exploration geoscientist for Shell International. He obtained an M.Sc. degree in geology from the University of Bristol and a Ph.D. from Imperial College, London. His Ph.D. was focused on the sedimentology and sequence stratigraphy of the poorly understood Krossfjord and Fensfjord Formations in the super-giant Troll field, offshore Norway and this manuscript forms part of his research. Gary J. Hampson ∼ Imperial College, Basins Research Group (BRG), Department of Earth Science & Engineering, Prince Consort Road, London, SW7 2BP, England, United Kingdom; g.j.hampson@imperial.ac.uk Gary Hampson is a reader in sedimentary geology in the Department of Earth Science and Engineering, Imperial College, London. He holds a B.A. degree in natural sciences from the University of Cambridge and a Ph.D. in sedimentology and sequence stratigraphy from the University of Liverpool. His research interests lie in the understanding of depositional systems and their preserved stratigraphy, and in applying this knowledge to reservoir characterization. Christopher A.-L. Jackson ∼ Imperial College, Basins Research Group (BRG), Department of Earth Science & Engineering, Prince Consort Road, London, SW7 2BP, England, United Kingdom; c.jackson@imperial.ac.uk Christopher Jackson is currently the Statoil reader in basin analysis in the Department of Earth Science and Engineering, Imperial College, United Kingdom. He obtained a B.Sc. degree and Ph.D. from the University of Manchester. His research interests are in the tectonostratigraphic evolution of rifts and the application of 3-D seismic data to understanding the formation and filling of sedimentary basins. Steen A. Petersen ∼ Statoil ASA, Sandsliveien 90, 5020, Bergen, Norway; steap@statoil.com Steen Agerlin Petersen is working for Statoil as researcher and specialist in reservoir geophysics. Petersen holds a Ph.D. in geology and geophysics from the University of Aarhus, Denmark. His research focuses on the simulation and AAPG Bulletin, v. 98, no. 12 (December 2014), pp. 2629–2663 2629