Outcrop gamma ray profiles and core from two wells drilled in the vicinity of outcrop exposures were used to document the facies architecture of the Almond Formation along the southeast flank of the Rock Springs uplift, Wyoming. The vertical succession shows a transition from continental (lower Almond) to marine (upper Almond) facies upsection indicating an overall transgressive origin. The identification of at least one lowstand surface of erosion and numerous transgressive surfaces however, indicate that the Almond is not a conformable succession.

Upper Almond sandstones have been interpreted as being deposited within a barrier island system. These sandstones show a great deal of internal complexity ranging from partial erosion of the barrier island by tidal channels to the complete reworking of barrier islands by tidal inlet migration. Some sandstones in the upper Almond also show a typical shoreface succession of lower to upper shoreface deposits, are progradational, and lack evidence of backbarrier facies. These successions are interpreted in this study as strandplains.

Because the most productive reservoirs occur in the upper Almond, the architecture documented in this study can be used as a model for subsurface correlations. The construction of outcrop gamma ray profiles also enables the visualization of lithologies based on their gamma ray response that coupled with core, further aids in the comparison from outcrop to subsurface. This approach can lead to better development of pre-existing producing trends in the Almond or the discovery of new, previously unidentified reservoirs.

AAPG Search and Discovery Article #90928©1999 AAPG Annual Convention, San Antonio, Texas