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Salinity increases in the navajo aquifer in southeastern Utah

Water Resources Bulletin

By:
,
DOI: 10.1111/j.1752-1688.1994.tb03357.x

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Abstract

Salinity increases in water in some parts of the Navajo aquifer in southeastern Utah have been documented previously. The purpose of this paper is to use bromide, iodide, and chloride concentrations and del oxygen-18 and deuterium values in water from the study area to determine if oil-field brines (OFB) could be the source of increased salinity. Mixing-model results indicate that the bromide-to-chloride X 10,000 weight ratio characteristic of OFB in and outside the study area could not be causing the bromide depletion with increasing salinity in the Navajo aquifer. Mixing-model results indicate that a mixture of one percent OFB with 99 percent Navajo aquifer water would more than double the bromide-to-chloride weight ratio, instead of the observed decrease in the weight ratio with increasing chloride concentration. The trend of the mixing line representing the isotopically enriched samples from the Navajo aquifer does not indicate OFB as the source of isotopically enriched water; however, the simulated isotopic composition of injection water could be a salinity source. The lighter isotopic composition of OFB samples from the Aneth, Ratherford, White Mesa Unit, and McElmo Creek injection sites relative to the Ismay site is a result of continued recycling of injection water mixed with various proportions of isotopically lighter make-up water from the alluvial aquifer along the San Juan River. A mixing model using the isotopic composition of the simulated injection water suggests that enriched samples from the Navajo aquifer are composed of 36 to 75 percent of the simulated injection water. However, chloride concentrations predicted by the isotopic mixing model are up to 13.4 times larger than the measured chloride concentrations in isotopically enriched samples from the Navajo aquifer, indicating that injection water is not the source of increased salinity. Geochemical data consistently show that OFB and associated injection water from the Greater Aneth Oil Field are not the source of salinity increases in the Navajo aquifer.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Salinity increases in the navajo aquifer in southeastern Utah
Series title:
Water Resources Bulletin
DOI:
10.1111/j.1752-1688.1994.tb03357.x
Volume
30
Issue:
6
Year Published:
1994
Language:
English
Publisher:
American Water Resources Association
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
First page:
1119
Last page:
1135
Number of Pages:
17