Facies-Specific Reservoir Rock Properties of a Back-Barrier Lagoon Deposit Interpreted From a Core-to-Outcrop Study in the Kaiparowits Plateau

Abstract

Transgressive, back-barrier lagoonal deposits contain sandstone intervals that could contribute to net pay in reservoir zones. However, the interpretation and spatial distribution of lithofacies within such zones is poorly documented, particularly within a hierarchical framework from grain to seismic scale. Thick (>300 m) intervals of preserved transgressive deposits in the John Henry Member of the Kaiparowits Plateau exposed in outcrop and sampled in subcrop cores provide an excellent opportunity to study the spatial distribution and heterogeneity in barrier island, shoreface, tidal inlet channel, washover fan, and ebb and flood tidal delta deposits. Five core descriptions are presented along strike of the paleoshoreline, averageing 3.7 km apart. Outcropping rock exposures of cored intervals are present along the same transect at a similar spacing. Core correlation is tied to outcrop to verify correlations and depositional environment interpretations and to quantify geobody size, shape, and distribution. Horizontal and vertical plugs sampled from two cores provide rock property information targeting grain-scale textural information (shape, sorting, mineralogy, clay type and distribution, cement-type and amount, and porosity) to core plug scale benchtop measurements (porosity, vertical and horizontal permeability, p- and s-wave velocity, and density). Results of this study present guidelines outlining the probability of misclassification of lithofacies from core and the probability of reservoir misclassification from seismic-reflectivity. We show how coupling seismic and core interpretation with rock properties within a robust depositional framework can act to reduce interpretation uncertainty and the risk of misclassification. Furthermore, this study presents predictive relationships between stratigraphic stacking patterns and lateral lithofacies changes impacting reservoir quality and seismic-reflectivity responses. Finally, the back barrier lagoon is placed in the context of previous studies in the Kaiparowits Plateau to outline play-scale reservoir potential.

AAPG Datapages/Search and Discovery Article #90291 ©2017 AAPG Annual Convention and Exhibition, Houston, Texas, April 2-5, 2017