Capillary controls can minimize the surface energy of pore spaces in rock salt and exert important control on brine percolation. Simulations of texturally equilibrated pore networks in real polycrystalline materials allow probing of basic properties like percolation thresholds and permeability relationships. Laboratory experiments are consistent with computed percolation thresholds, while field data from wells show fluid commonly invades deeper sections of salt domes, consistent with brine beginning to wet grain boundaries at higher pressures and temperatures. However, in some domes fluid has percolated to shallower depths, likely due to shear deformation not accounted for in theory and experiments.

1. Capillary controls on brine percolation in rock salt
Marc Hesse and Masha Prodanovic
The ability the microstructure in rock salt to evolve to minimize the surface energy of the pore-
space exerts an important control on brine percolation. The behavior is especially interesting
under conditions when brine is wetting the grain boundaries and the pore network percolates at
very low porosities, below the transport threshold in typical porous media. We present pore-scale
simulations of texturally equilibrated pore spaces in real polycrystalline materials.
This allows us to probe the basic physical properties of these materials, such as percolation and
trapping thresholds as well as permeability-porosity relationships. Laboratory experiments in
NaCl-H2O system are consistent with the computed percolation thresholds. Field data from
hydrocarbon exploration wells in rock salt show that fluid commonly invades the lower sectionof
the salt domes. This is consistent with laboratory measurements that show that brine begins to wet
the salt grain boundaries with increasing pressure and temperature and theoretical arguments
suggesting this would lead to fluid invasion. In several salt domes, however, fluid have
percolated to shallower depths, apparently overcoming a substantial percolation threshold. This is
likely due to the shear deformation in salt domes, which is not accounted for in theory and
experiments.