Eolian Reservoir Models: A Study of the Heterogeneity and Reservoir Characterization of the Red Head Sandstone, Five Islands, Nova Scotia.

Abstract

The Red Head Sandstone is located at Five Islands, along the northern shore of the Minas Subbasin, Colchester County, approximately 160 km north of Halifax, Nova Scotia. The outcrop comprises approximately 33 m of red sandstones interpreted as deposited under primarily eolian conditions. The type section marks the complete transition from a braided channel sandstone of the Wolfville Formation through the eolian succession to the overlying playa lake mudstones of the Blomidon Formation. Red Head point presents a three-walled amphitheatre allowing for a unique near complete internal 3D visualization of the eolian succession. Thus, the arrangement of facies in outcrop reveals eolian depositional end members of varying scales, and complex dune architecture likely resulting from an interaction between the major controlling factors (wind and tectonics). A variance in these factors likely prompted a localized reworking of sediments by winds from different directions, proximal to the basin border fault. There has been a stratigraphic debate regarding the host formation of the eolian sandstones, with some researchers assigning it as the upper member of the Wolfville Formation, while others assign it as a lower member of the Blomidon Formation. Previous work on the Wolfville Formation relating to the stratigraphic controls on basin evolution suggests a paleoflow direction to the north based on the orientation of bar forms. Furthermore, eolian dune strata have been reported across the basin to the south between Kingsport and Medford, where it is recorded as a unit of the Upper Wolfville Formation. However, the good sorting and good to excellent visible porosity exhibited by the Red Head Sandstone, combined with the large-scale southwest dipping cross beds are a distinguishing characteristic between the Red Head eolian sandstones and the underlying fluvial sandstones of the Wolfville Formation, which exhibit decreased porosity. In this study, we provide a detailed description of the facies and interpretation of architectural elements by applying an integrated approach including digital photographs, supplemented by terrestrial laser scans, outcrop sedimentary logs and thin section petrography. Grab samples for XRF analysis, portable handheld spectrometer and air permeameter measurements, were utilised to investigate the reservoir characteristics of the Red Head Sandstone. Finally, we compare our results with those previously observed in the Wolfville Formation.

AAPG Datapages/Search and Discovery Article #90259 ©2016 AAPG Annual Convention and Exhibition, Calgary, Alberta, Canada, June 19-22, 2016