Abstract

Permeability distributions of the unconsolidated sediments of the Weber River delta are important as the delta is a significant ground-water recharge area and aquifer for the heavily populated Wasatch Front. Coupling this study’s permeability analysis with the established stratigraphic framework of the delta may serve as a starting point for further research on modeling ground-water flow through the delta.

The Weber River delta is a sandy lacustrine delta deposited along the eastern margin of late Pleistocene Lake Bonneville, near Ogden, Utah. Thirteen lithofacies and five architectural elements (assemblages of lithofacies) have been described in the delta. Permeabilities were estimated on over 400 minimally disturbed sediment cores from five lithofacies and three architectural elements. Average measured horizontal permeabilities ranged from 0.1 to 18.1 darcys. Average measured vertical permeabilities ranged from 0.07 to 19.0 darcys.

Permeability measurements from randomly selected cores from outcropping lithofacies of a single architectural element cannot reject tests for either normal or lognormal statistical distributions. When the same lithofacies of different architectural elements are combined, the sample sets typically do reject tests for both normal and lognormal statistical distributions. Sampling permeability along a single bed of a lithofacies of a single architectural element cannot reject tests for either normal or lognormal distributions. Also, the permeability distribution of similar lithofacies within a single architectural element cannot reject tests for either normal or lognormal distributions. However, the permeability distribution of similar lithofacies within different architectural elements usually rejects tests for both normal and lognormal distributions. The Weber River delta is volumetrically composed of primarily delta front and lacustrine clay sedimentary deposits. Thus, using lithotypes (similar lithofacies with respect to sediment measurements) within single architectural elements could reduce the number of lithofacies within each architectural element. This would simplify what must be distinguished in fluid flow models and begin to “scale-up” the model while preserving the integrity of the permeability distributions.