--> ABSTRACT: A Sedimentological Process Based Approach to Reservoir Modeling in Complex Deepwater Reservoirs: Wilcox Formation Gulf of Mexico, by Pontén, Anna S.; Quin, Jamie ; Otterlei, Cecilie; Messina, Carlo; Kane, Ian A.; Henriksen, Sverre; Fält, Lars-Magnus; Nordahl, Kjetil; Talukdar, Saifullah; #90142 (2012)

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A Sedimentological Process Based Approach to Reservoir Modeling in Complex Deepwater Reservoirs: Wilcox Formation Gulf of Mexico

Pontén, Anna S.*1; Quin, Jamie 1; Otterlei, Cecilie 2; Messina, Carlo 3; Kane, Ian A.4; Henriksen, Sverre 1; Fält, Lars-Magnus 1; Nordahl, Kjetil 1; Talukdar, Saifullah 2
(1) Statoil GoM & Brazil R&D, Statoil ASA, Trondheim, Norway.
(2) Statoil GoM & Brazil R&D, Statoil ASA, Bergen, Norway.
(3) Statoil Global New Ventures, Statoil ASA, Oslo, Norway.
(4) Statoil Exploration R&D, Statoil ASA, Bergen, Norway.

Whilst large hydrocarbon volumes have been identified within the Palaeogene Wilcox play (Deepwater Gulf of Mexico), their extraction poses significant production challenges: reservoirs are subsalt, have low permeability and are heterogeneous. High drilling costs and a lack of production history make improved core- and well-based reservoir characterization an essential, and relatively inexpensive, step in exploitation. Capturing and modeling the spatial and stratigraphic distribution of reservoir properties requires classification and sub-division of reservoir lithologies; however, in sedimentologically complex reservoirs such as the Wilcox, classical lithofacies sub-divisions (i.e. structureless sandstones, plane parallel stratified sandstones etc.) do not discriminate hydrocarbon flow properties sufficiently.

Here, we define individual event beds which are the deposits of single gravity flows, and assign them to a process-based bed-type subdivision. The bed-type subdivision includes high- and low-density turbidites, debrites, composite and transitional flow deposits, and sustained flow turbidites deposited from sustained/fluctuating flows. This process-driven interpretation allows the reservoir property data to be systematically captured and distributed within reservoir models. For the Wilcox, this approach was used to develop a fine-scale object-based stochastic reservoir model (3 inch vertical resolution) which captures the uncertainty of the fine-scale heterogeneity and the petrophysical variation between the depositional environments.

Flow simulations have been performed on the reservoir model where properties are distributed for different bed types and compared to a model with a traditional coarse-scale facies scheme approach. The purpose was to study how the heterogeneities influence the production and drainage strategy. This sedimentological process-based approach to reservoir description adds predictive power to the conceptual model of the Wilcox, and provides a more robust basis for decisions on wells and drainage strategy for individual fields, which reduces the investment risk.

 

AAPG Search and Discovery Article #90142 © 2012 AAPG Annual Convention and Exhibition, April 22-25, 2012, Long Beach, California