AAPG Studies in Geology No. 50, (Section Title: Outcrop Case Studies) Chapter 12: Geologic Framework of the Lower Portion of the Ferron Sandstone in the Willow Springs Wash Area, Utah: Facies, Reservoir Continuity, and the Importance of Recognizing Allocyclic and Autocyclic Processes, by John A. Dewey, Jr. and Thomas H. Morris, Pages 305 - 330
from:
AAPG Studies in Geology No. 50: Regional to Wellbore Analog for Fluvial-Deltaic Reservoir Modeling: The Ferron Sandstone of Utah, Edited by Thomas C. Chidsey, Jr., Roy D. Adams, and Thomas H. Morris
Copyright © 2004 by The American Association of Petroleum Geologists and the Society of Exploration Geophysicists. All rights reserved.

Outcrop Case Studies

Chapter 12:
Geologic Framework of the Lower Portion of the Ferron Sandstone in the Willow Springs Wash Area, Utah: Facies, Reservoir Continuity, and the Importance of Recognizing Allocyclic and Autocyclic Processes

John A. Dewey, Jr.¹ and Thomas H. Morris^2
1Anadarko Petroleum Corp., The Woodlands, Texas
²Department of Geology, Brigham Young University, Provo, Utah

ABSTRACT

Three-dimensional outcrop exposures of the Ferron Sandstone in the Willow Springs Wash area of east-central Utah illustrate the importance of recognizing allocyclic and autocyclic processes in marginal-marine settings. Three chronostratigraphically distinct wave-dominated shoreline sandstone successions display vertical offset at their landward pinchouts. These coarsening upward successions are interpreted to be parasequences produced by allocyclic processes. Fluids trapped within these sandstones may be compartmentalized by this vertical offset. In contrast, a fluvial-dominated coarsening upward succession, interpreted to have been produced by autocyclic delta lobe-switching processes, displays no vertical offset between its landward pinchout and an underlying wave-dominated parasequence. In a landward direction, these two distinct sandstone bodies merge into one and fluids migrating updip would not be compartmentalized. Reservoir continuity is further complicated by younger multi-lateral and multi-story distributary channels that can incise into previously deposited marine parasequences, thereby creating a fluid pathway between these otherwise isolated sandstone bodies.