Fluvial-Aeolian Interactions Within Arid Continental Basins: Implications for Reservoir Characterisation and Basin Modelling

Abstract

Arid continental basins commonly comprise sedimentary fill from fluvial and aeolian environments, and while the preserved facies associations within each environment have been studied in great depth, the relationships between coeval depositional environments have received little attention. The temporal and spatial distributions of these environments can greatly affect reservoir quality and basin-scale migration.

We present results from interactions of fluvial and aeolian deposits of the Kayenta Formation across the Colorado Plateau, USA, from proximal to distal, along with insights into the allocyclic controls upon them. These studies are based upon extensive regional fieldwork to examine the sedimentology, utilising 3D photogrammetry techniques to examine geometries and interactions, as well as comparing and contrasting field data to a small core study on the Leman Sandstone reservoir in the Southern North Sea, UK.

The Kayenta Formation comprises fluvial-aeolian associations of varying reservoir quality. Relationships between them are spatially predictable, governed by one system’s dominance. A dominant aeolian system limits fluvial sediments to interdune corridors and controls localised sediment supply, resulting in flash-flood and debris facies of moderate reservoir quality, comprising sediments of aeolian calibre and texture. Dominance of the fluvial system restricts aeolian bedforms and preserves extensive ephemeral fluvial sediments of poor reservoir quality, with fluvial textures dominated by extraformational sediment. The temporal evolution between systems preserves unique facies, but a switch in dominant system takes place quickly, severely limiting the vertical extent of interactions and potentially isolating reservoir intervals of basin fill.

Field data coupled with 3D photogrammetric models allow reconstruction of these ancient channel forms and dune fields, providing useful information for quantifiable reservoir models. This can help better characterise basin-scale migration and reservoir quality within the basin fill. We apply our model to the Lower Permian Leman Sandstone, a principal gas reservoir in the Southern North Sea Basin, adding increased complexity to further enhance recovery.

AAPG Datapages/Search and Discovery Article #90323 ©2018 AAPG Annual Convention and Exhibition, Salt Lake City, Utah, May 20-23, 2018