MAJOR OIL PLAYS IN UTAH AND VICINITY

Utah oil fields have produced over 1.2 billion barrels (191 million m{sup 3}). However, the 13.7 million barrels (2.2 million m{sup 3}) of production in 2002 was the lowest level in over 40 years and continued the steady decline that began in the mid-1980s. The Utah Geological Survey believes this trend can be reversed by providing play portfolios for the major oil-producing provinces (Paradox Basin, Uinta Basin, and thrust belt) in Utah and adjacent areas in Colorado and Wyoming. Oil plays are geographic areas with petroleum potential caused by favorable combinations of source rock, migration paths, reservoir rock characteristics, and other factors. The play portfolios will include: descriptions and maps of the major oil plays by reservoir; production and reservoir data; case-study field evaluations; summaries of the state-of-the-art drilling, completion, and secondary/tertiary techniques for each play; locations of major oil pipelines; descriptions of reservoir outcrop analogs; and identification and discussion of land use constraints. All play maps, reports, databases, and so forth, produced for the project will be published in interactive, menu-driven digital (web-based and compact disc) and hard-copy formats. This report covers research activities for the fourth quarter of the first project year (April 1 through June 30, 2003). This work included describing outcrop analogs to the Jurassic Nugget Sandstone and Pennsylvanian Paradox Formation, the major oil producers in the thrust belt and Paradox Basin, respectively. Production-scale outcrop analogs provide an excellent view, often in three dimensions, of reservoir-facies characteristics and boundaries contributing to the overall heterogeneity of reservoir rocks. They can be used as a ''template'' for evaluation of data from conventional core, geophysical and petrophysical logs, and seismic surveys. The Nugget Sandstone was deposited in an extensive dune field that extended from Wyoming to Arizona. Outcrop analogs are found in the stratigraphically equivalent Navajo Sandstone of southern Utah which displays large-scale dunal cross-strata with excellent reservoir properties and interdunal features such as oases, wadi, and playa lithofacies with poor reservoir properties. Hydrocarbons in the Paradox Formation are stratigraphically trapped in carbonate buildups (or phylloid-algal mounds). Similar carbonate buildups are exposed in the Paradox along the San Juan River of southeastern Utah. Reservoir-quality porosity may develop in the types of facies associated with buildups such as troughs, detrital wedges, and fans, identified from these outcrops. When combined with subsurface geological and production data, these outcrop analogs can improve (1) development drilling and production strategies such as horizontal drilling, (2) reservoir-simulation models, (3) reserve calculations, and (4) design and implementation of secondary/tertiary oil recovery programs and other best practices used in the oil fields of Utah and vicinity. During this quarter, technology transfer activities consisted of exhibiting the project plans, objectives, and products at a booth at the 2003 annual convention of the American Association of Petroleum Geologists. The project home page was updated on the Utah Geological Survey Internet web site