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Hodgetts, David1, Nicholas Drinkwater2, Eirik Vik3, David Hodgson1, Stephen Flint1, Erik Johannessen4, Stefan Luthi5 
(1) University of Liverpool, Liverpool, United Kingdom 
(2) Schlumberger Cambridge Research, Cambridge, United Kingdom 
(3) Statoil, Trondheim, Norway 
(4) Statoil, Stavanger, Norway 
(5) Delft University of Technology, Delft, Netherlands

ABSTRACT: Reservoir Modeling of Deepwater Basin Floor Fans, Karoo Outcrops, South Africa 1: Methods of Data Collection, Model Building and Interrogation

Integration of DGPS mapped key surfaces, 250 GPS-positioned logged sections, 7 fully cored wells and over 200 km of photopanels, which has enabled construction of partly deterministic 3-D reservoir models for Fans 2, 3 and 4 in the Tanqua depocentre, SW Karoo Baisn, South Africa using Schlumberger’s PETREL and Roxar’s RMS software. The fan model areas varied significantly from fan to fan – the Fan 3 model covered the entire 35 x 15 km outcrop area while the Fan 4 model, due to outcrop quality, samples a “postage stamp” area from the northern part of the outcrop belt. Building models from outcrops ensure large volumes of data but also introduce problems such as datum difficulties, removal of section through recent erosion and limited definition of a 3-D volume. A standardised modelling methodology was developed for all 3 fans, consisting of: (1) development of a structural model derived from extensive Digital GPS outcrop data of fan bases and tops and the network of sub-seismic reverse faults (2) zonation of each fan system into fan-wide cycles that comprise sand-prone growth phases and silt- and shale-prone phases reflecting reduction of sand supply, (3) derivation of facies shapes, sizes and distributions from outcrop studies, (4) conditioning of object modelling by a combination of flow lines based on paleocurrents (outcrop and FMI derived), probability maps, bed thickness and facies distributions from logs and boreholes and amalgamation indices, and (5) deterministic introduction of features such as the key channels using a variety of modeling approaches.


AAPG Search and Discovery Article #90026©2004 AAPG Annual Meeting, Dallas, Texas, April 18-21, 2004.