EBY, DAVID E., Eby Petrography & Consulting, Inc., Englewood, CO, and WILSON G. GROEN and JOHN F. JOHNSON, Chuska Energy Company, Denver, CO

ABSTRACT: Composition of Seismically Identified Satellite Mounds Surrounding Greater Aneth Field, Southeast Utah

Five different types of satellite mounds have been encountered during drilling and extensive coring of approximately 40 high-resolution CDP (common depth point) seismic anomalies in the Desert Creek interval of the Pennsylvanian (Desmoinesian) Paradox Formation around the periphery of Greater Aneth field. The composition and diagenetic modification of these mound types directly affect the quality of porosity and permeability within

each satellite buildup. The mound types and their principal characteristics are (1) crinoid-sponge limestone with wackestone to packstone fabrics; (2) coralline algal boundstones that are slightly dolomitized; (3) bryozoan-dominated lime boundstones with no significant dissolution porosity; (4) phylloid algal bafflestones with extensive dissolution and some dolomitization occasionally overlain by dolomitized stromatolitic/thrombolitic boundstones; and (5) stacked bioclastic grainstones with extensive dissolution and complete dolomitization.

Controls on the development of each mound type appear to be a function of water depth and prevailing water energy. Mound types 1 and 2 typically have low porosity, whereas type 3 preserved primary porosity. Types 4 and 5 commonly exhibit extensive porosity and permeability modification through freshwater dissolution and early dolomitization. Up to five cycles of buildup growth can occur within the Desert Creek satellite mounds. Mound composition types will recur or change to another growth type depending upon local water depth and energy conditions. Calibration of seismic amplitude variations can be used in imaging reservoir size and porosity variation.

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