Reservoir Characterization of the Lower Green River Formation, Southwest Uinta Basin, Utah.

摘要

The oil-productive lower and middle members of the Green River Formation in the southwest Uinta Basin are divided into five distinct reservoirs. The reservoirs in stratigraphically ascending order are: (1) Uteland Butte, (2) Castle Peak, (3) lower Douglas Creek, (4) upper Douglas Creek, and (5) Garden Gulch. The changing depositional environments of Lake Uinta controlled the characteristics of each of the reservoirs. The Uteland Butte consists of carbonate and rare, thin shallow-lacustrine sandstone bars deposited during the initial rise of the lake. The Castle Peak reservoir was deposited during a time of numerous and rapid lake-level falls and rises, which developed a simple drainage pattern across the exposed shallow and gentle shelf with each cycle. The lower Douglas Creek Reservoir records a time of active tectonism which created a steeper slope and a pronounced shelf break where thick cut-and-fill valleys developed during lake-level falls and rises. The upper Douglas Creek reservoir represents a return to a very gentle shallow shelf where channel deposits became stacked in a lowstand delta plain and amalgamated into some of the best reservoir rock in the southwest Uinta Basin. The Garden Gulch reservoir represents a time of major lake expansion with fewer, less pronounced lake-level falls, resulting in isolated single-storied channel- and shallow-bar sandstone deposits.