Abstract

Oil from the lower and middle Green River Formation, in Monument Butte field, Uinta Basin, Utah, is produced from a complex network of low net:gross fluvial-lacustrine sandstones. The productive interval is more than 2,000 ft thick, and wells typically encounter about 50 ft of pay, spread out over 6 to 12 different pay zones. Editing and controlling the quality of zone and tops data in more than 2,000 wells with thin pay scattered over a large gross interval have proven challenging. Without a consistent framework, reservoir properties have never been mapped properly. In this study, a new method of reservoir zonation has been developed using statistically derived proportional tops, which create a detailed, genetic sequence stratigraphic framework that can be generated quickly at every well and that is easily updated and controlled for quality. Proportional zonation allows reservoir properties (i.e., net sand, average porosity, fluid saturations, etc.) to be calculated and mapped fieldwide in high stratigraphic detail. Improved modeling of reservoir character and distribution allows better integration of production, injection, and zone data. Data integration in a sequence stratigraphic framework provides new insights for improving reservoir management and optimizing production.