| Abstract: | Methods and systems for estimating conductivity of clay mineral systems,
and for applying the estimates in larger-scale analysis. Conductivity of
the clay may be estimated by constructing a molecular model of an
anhydrous charge-neutral clay, and then assigning a charge density by
substitution of ions in the model of the clay structure. Counterions are
inserted for charge neutrality, and water molecules are added to the
model to reflect a selected level of hydration. Following assignment of
force-field coefficients, molecular dynamics simulation provides data
from which diffusion coefficients can be estimated. Application of the
Nernst-Einstein relationship to the diffusion coefficients of the
counterions provides the ion conductivity of the clay system. This
conductivity can be used to derive a formation factor, and can be applied
in direct numerical simulation analysis. |