Permian Salt Dissolution in Silo Field, Laramie County, Wyoming

Abstract

Within Silo Field, a Permian salt edge exists. This salt edge was believed to be the cause of faulting and fracturing within the Niobrara Formation but studies have shown that this is not the case. Using a 3-D seismic survey encompassing approximately 30 square miles, the nature of the salt edge was examined. The irregular shape of the salt edge suggests that it was caused by dissolution rather than deposition. Dissolution occurred during the Late Jurassic and Early Cretaceous. Two of the proposed mechanisms for salt dissolution include: compaction-driven water migration in the Lyons Formation and basement tectonics. Based on the seismic patterns observed, basement tectonics was the likely control on the location of the salt edge but further analysis is required to determine the role played by the Lyons Formation. The Permian salt also has an effect on the overall structure of Silo Field. The field exhibits a structural monocline in all of the strata overlying the Permian salt. Differential compaction over the salt edge creates the monocline. However, basement structure also has some control on the structural monocline. The lack of salt and timing of dissolution caused a thickened Dakota-Sundance interval in the southwestern part of the survey area. It is possible that this thickened section is the cause for high water production from the Niobrara in Silo Field. Understanding the nature of the Permian salt edge in Silo Field could have implications for understanding Permian salt dissolution and its impact in other Rocky Mountain fields.

AAPG Datapages/Search and Discovery Article #90193 © 2014 Rocky Mountain Section AAPG Annual Meeting, Denver, Colorado, July 20-22, 2014