Publications

Field-scale Thermal Testing in a Generic Salt Disposal Environment Underground Research Laboratory (URL): Delineation of Principal Purpose Objectives and Hypotheses

Sassani, David C.; Hardin, Ernest H.; Kuhlman, Kristopher L.; MacKinnon, R.J.

The amount of brine present in domal salt formation is far less than in bedded salts (e.g., 0.01 to 0.1% compared with 1 to 3%). In salt domes, shear deformation associated with diapirism has caused existing brine to coalesce, leading to flow and expulsion. Brine migration behavior was investigated in bedded salt at WIPP (Nowak and McTigue 1987, SAND87-0880), and in domal salt at Asse (Coyle et al. 1987, BMI/ONWI-624). Test methods were not standardized, and the tests involved large diameter boreholes (17 to 36 in. diameter) and large apparatus. The tested intervals were proximal to mined openings (within approximately 1 diameter) where in situ stresses are redistributed due to excavation. The tests showed that (1) brine inflow rates can range over at least 2 orders of magnitude for domal vs. bedded salt, (2) that brine inflow is strongly associated with clay and interbedded permeable layers in bedded salt, and (3) that measurement systems can readily collect very small quantities of moisture over time frames of 2 years or longer. Brine inflow rates declined slightly with time in both test series, but neither series approached a state of apparent depletion. This range of flow magnitude could be significant to repository design and performance assessment, especially if inflow rates can be predicted using stratigraphic and geomechanical inputs, and can be shown to approach zero in a predictable manner.