2014 Rocky Mountain Section AAPG Annual Meeting

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Calibration of petrophysical log response in the north and eastern Uinta Basin to allow extension of outcrop belts into the subsurface using well data.


The Green River Formation of the Uinta Basin, Utah is a proven petroleum system with many existing, highly productive fields in sandstone and carbonate facies. Other, finer-grained facies (siliceous and carbonate mudrocks) have been identified as potential basin wide unconventional plays. The economics of individual wells, however, are highly dependent on local facies, which are currently difficult to predict. This complication arises from the discontinuous nature of depositional units, compounded by the unusual log responses observed within the Green River Formation. This study focuses on the eastern portion of the Uinta basin, which is constrained by the Uinta Uplift in the north, the Douglas Creek Arch to the east and the Uncompahgre Uplift to the south. Through detailed study of outcrop, incorporating spectral gamma ray, combined with correlation of cores, a better technique for calibrating logs is defined. By combining a number of petrophysical properties, using porosity, gamma ray, and resistivity logs, misinterpretations of facies due to unusual log responses can be avoided. The calibration technique was used to interpret well logs across the east of the basin and then generate a number of regional cross-sections to provide a framework for higher resolution correlations at a localized scale and thus better prediction of reservoir quality. These regional lines expand upon existing work done on Ravens Ridge in the north east of the basin and in the adjacent Piceance basin.