GARRISON, JAMES R., JR., and LARRY D. SMALLWOOD, Mobil Exploration and Producing Technical Center, Dallas, TX

ABSTRACT: Preliminary Analysis of the Architecture, Lithology, and Permeability Structure of a Ferron Sandstone Sequence 2 Distributary-Channel Belt, Willow Springs Wash, Emery County, Utah

Detailed geologic mapping, laser surveying, video measured sections, and outcrop gamma-ray spectrometry indicate that the Ferron Sandstone sequence 2 distributary-channel belt in Willow Springs Wash is composed of up to twelve major elements, deposited during three major events. The lower five elements represent scour and fill macroforms deposited within a narrow (300-ft wide) confined channel during a major (rapid) seaward deltaic progradational phase. These macroforms are dominated by trough cross-stratification and are delineated by clay-clast-lined scour bounding surfaces. The second phase of channel-belt development is recorded by the next five higher macroform elements, which were deposited in a much wider, yet confined, channel (800 ft wide) reflecting a minor base level change These barforms have cut and fill characteristics, as well as containing lateral accretionary surfaces and planar and tabular cross-stratification. The final phase of channel-belt deposition, reflecting yet another significant base level change, is dominated by laterally accreting barform facies (1000 ft wide) with well-developed levels and overbank facies dominated by small-scale planar and tabular cross-stratification. Video measured sections, outcrop gamma ray, grain-size analysis, and mini-probe permeametry of selected vertical and horizontal transects indicate that (1) major bounding elements between macroforms are characterized by high gamma-ray counts, (2) general correlations of gamma ray and permeability (range = 1-2300 md; mean = 90 md) indicate that permeability is controlled y grain-size and bed-form characteristics, and (3) local permeability systematics are controlled by macroform type.

AAPG Search and Discovery Article #90993©1993 AAPG Rocky Mountain Section Meeting, Salt Lake City, Utah, September 12-15, 1993.