When pH and alkalinity increase, calcite frequently
precipitates and hence modifies the
petrophysical properties of porous media. The compl
ex conductivity method can be used to
directly monitor calcite precipitation in porous me
dia because it is sensitive to the evolution of
the mineralogy, pore structure and its connectivity
. We have developed a mechanistic grain
polarization model considering the electrochemical
polarization of the Stern and diffuse layer
surrounding calcite particles. Our complex conducti
vity model depends on the surface charge
density of the Stern layer and on the electrical po
tential at the onset of the diffuse layer, which ar
e
computed using a basic Stern model of the calcite/w
ater interface. The complex conductivity
measurements of Wu
et al.
(2010) on a column packed with glass beads where ca
lcite
precipitation occurs are reproduced by our surface
complexation and complex conductivity
models. The evolution of the size and shape of calc
ite particles during the calcite precipitation
experiment is estimated by our complex conductivity
model. At the early stage of the calcite
precipitation experiment, modeled particles sizes i
ncrease and calcite particles flatten with time
because calcite crystals nucleate at the surface of
glass beads and grow into larger calcite grains
around glass beads. At the later stage of the calci
te precipitation experiment, modeled sizes and
cementation exponents of calcite particles decrease
with time because large calcite grains
aggregate over multiple glass beads, a percolation
threshold is achieved, and small and discrete
calcite crystals polarize.