Summary

Heterogeneity in aeolian systems exists at a number of scales and will affect fluid movement through the reservoir to greater or lesser extents. Detailed descriptions of these heterogeneities are common in the literature (i.e. Chandler et al. 1989). Recently, characteristics of these heterogeneities have been incorporated into reservoir models and their associated up-scaled flow simulations in an attempt to predict reservoir performance (Sweet et al. 1997).

The distribution of these heterogeneities is a function of the system architecture which results from the type of aeolian system (or part of the system) that the reservoir sequence was deposited in. Therefore, the key to accurate reservoir prediction lies in the correct interpretation of the subsurface system, so that the appropriate architecture is honoured in the reservoir modelling and simulation.

Two end member 3D reservoir models were constructed, using analogous outcrop sequences (Cutler Formation and Slickrock Mbr. of the Entrada Formation) to determine size distributions and architecture of fluvial influenced and marine influenced aeolian systems respectively. These models were upscaled and subjected to depletion/aquifer incursion simulations to replicate similar conditions to those experienced during initial production from Southern North Sea gas reservoirs. The results indicate that significant differences in water breakthrough and flood front morphology are experienced as a function of the architecture, thus illustrating the importance of accurate architectural determination prior to simulation if realistic prediction is to be achieved

AAPG Search and Discovery Article #90937©1998 AAPG Annual Convention and Exhibition, Salt Lake City, Utah