By: Federico Rueda Chaparro, Hans G. Machel, and Michael D. Vanden Berg
The lacustrine Eocene Green River Formation (GRF) is an important oil-producing formation in the Uinta Basin, Utah (USA). In recent years, the unconventional carbonate reservoirs in the Uteland Butte member (UBm), base of the GRF, have been targeted because of their significant oil and gas resources. The stratigraphic interval of interest lies between the informally named D and C shales, in which there are three dolomite layers named PZ2, PZ1â€², and PZ1 that vary from 1.5 to 8 feet in thickness and have up to 30% porosity but only a maximum of 0.1 mD permeability.
The objectives for this study are to characterize the depositional facies types and determine how they are related to dolomitization, to elucidate the dolomitization and how porosity and permeability are related to this process, and to delineate the regional geometry of the dolomite layers. This study employed several methods: outcrop and core descriptions; petrographic analysis (transmitted light, cathodoluminescence, and scanning electron microscopy); mineralogical identification and ordering of dolomites (XRD); elemental composition of dolomite crystals (EDS and EMPA); major and trace element analysis (ICP-MS); and conventional and clumped oxygen and carbon stable isotope analyses.
Media Type: Paper Publication