Abstract

Vertical permeability is a critical parameter to estimate when modeling tidally influenced deltaic successions. The Campanian Sego Sandstone, in the Book Cliffs of Utah, is an outcrop analog for tidal systems with primary reservoirs being deposited as tidal bars in both confined and unconfined settings. A simple sand-shale model was used to quantify the effective vertical permeability using the shale character of the Sego Sandstone. Shale lengths, widths, thicknesses, and frequencies were measured from high-resolution light detection and ranging point clouds. Shales in confined tidal bars are approximately three times as long (mean, 16.3 m [53.5 ft]) and as wide (mean, 5.52 m [18.1 ft]). Within unconfined tidal bars, shales are roughly equidimensional (mean length, 18.6 m [61.0 ft]; mean width, 18.3 m [60.0 ft]). The different shale dimensions of confined and unconfined tidal bars result in different effective vertical permeability distributions, indicating that these two bar types behave differently under conditions of fluid flow. In analogous reservoirs, composed primarily of tidal bars, it is essential to differentiate and map confined and unconfined tidal environments.

You do not currently have access to this article.