Properties and Behavior of Reservoir Oil in the Aneth Field, Utah

Abstract

Abstract Data are presented which show the PVT characteristics of the reservoir oil in the Aneth field, San Juan County, Utah. The data were obtained principally from the analysis of subsurface oil samples taken from seven wells within two years after discovery of the field. The uniformity of the oil across the large producing area is discussed and information on the development history and geology of the area is also given. The Aneth field is the first of several fields to be studied to provide data for a general investigation of the relative characteristics of Pennsylvanian reservoir oils in the Paradox basin. Introduction PVT characteristics of reservoir oil in the Aneth field, as reported here, were determined to provide part of the information needed for a comparative study of the characteristics of Pennsylvanian reservoir oils in the Paradox basin. The study proposes to determine if variations in oil characteristics occur in the basin which may reflect the source and migration history of the oil and also provide evidence of the effect of differential entrapment, as proposed by Gussow. The Paradox basin appeared opportune for this study because of the recent development of several producing fields and an oil potential indicated to be of national significance. Aneth is the largest field discovered thus far and is the first field studied. Other studies are in progress of the McElmo Creek, Ratherford and White Mesa fields to the south and southeast of Aneth and will be covered in future reports. Results of the Aneth and other field studies are being reported to inform the oil industry of the nature and behavior of reservoir oils in this new productive area and to make these data generally available for use in control of reservoir performance. A more detailed presentation of results of the Aneth field study may be obtained from a Bureau of Mines report.