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Basin-Scale Modeling of Jurassic and Late Cretaceous Reservoirs in the Uinta Basin, Utah, for Produced-Water Management and CO2 Storage


Basin-scale modeling of the Jurassic Navajo and Entrada Sandstone and the Late Cretaceous Dakota-Cedar Mountain Formations (undifferentiated) was conducted for two projects: (1) to calculate the CO2 storage capacity for the NATCARB database and (2) to evaluate water production from and potential disposal of water into reservoirs in the Uinta Basin. Several other reservoirs not discussed here were modeled for both projects. Mapping for the projects consisted of structure, gross and net thickness, net feet of porosity, and bubble maps of cumulative and monthly gas and water production. Water quality data were collected for the three reservoirs, which show spatial and depth variation of both quality and composition. Maps were first hand contoured in order to make reasonable projections into deeper portions of the basin where well control is lacking. Each of the contour maps was digitized, creating point data every 3000 feet along each contour line. The contour data points were added to the well data and then gridded in ArcMap. An average porosity value was assigned to each grid cell for calculation of storage. However, the average porosity resulted in an overestimation of storage capacity in the deeper portions of the basin where porosity is often significantly lower than the average. To improve the models we calculated feet of sandstone with 6% and 12% porosity using porosity logs. We then plotted the ratios of feet of 6% and 12% porosity over total feet of sandstone against depth. A ratio-depth equation was calculated for each reservoir and the models were recalculated. Areas of high CO2 storage capacity are assumed to also have high waste-water storage potential.