3-D Geometrical Simulations of LOSCs (Laterally Offset Stacked Channels)
Richard Labourdette1, Sebastien Ducos2, and Tarick Bahraoui2
1 Total S.A, Pau, France
2 Pau University, Pau, France
Reservoir modeling commonly requires a description of sedimentary heterogeneity on a scale smaller than that given by seismic resolution. In particular, complexes of Laterally Offset Stacked turbidite Channels (LOSCs) require a description at the scale of individual channel bodies, while seismic data only displays the outside geometry of their lateral stack, i.e. a turbidite fairway.
The most common representation of channels in a fairway is by stochastic object modeling; i.e., populating the observed fairway by realistic shapes representing individual channels, but without ensuring a consistency between the individual channels. On the other hand, one essential characteristic of LOSCs is to evolve by progressive migration laterally and/or downdip. Stochastic object modeling fails to adequately represent this progressive evolution, and therefore provides a poor rendering of the distribution of heterogeneity in the reservoir.
The method we propose consists in defining a realistic succession of individual channels that can build the fairway observed on seismic. “Realism” is defined using criteria on the shape of individual channels, and on the amount of displacement that is allowed between successive episodes. Depending on seismic resolution, the system can be constrained by one or several positions of individual channels (the last position of the channel is often filled by shale, therefore visible on seismic and usable as a control point).
The final result is a deterministic succession of channels laterally stacked to build the seismically observed envelope. Even in the absence of any calibration, the resulting architecture will honor the general “texture” of the complex, and provides a better simulation of flow pathways than random object modeling.