Page 160 - Percolation Models for Transport in Porous Media With

Chapter 9

Changing Conductivity and

Pore Space Structure with

Electric Current.

Experiments

9.1 Conductivity of Sandy-Argillaceous Medium

We shall analyze the results of laboratory experiments on the electric treatment
of a sandy-argillaceous rock by a "small-density" current. These experiments were
carried out to study the nature of reversible changes to the permeability and the
electric conductivity depending on the value of the electric field intensity, the
duration of the electric treatment, and the total energy released per unit mass of
the rock.
The experimental set-up completely coincides with the one presented in fig.
41. Voltage is supplied from a source of impulse or alternating current via the
power electrodes at the ends of the tube. The electrodes located in the middle
part of the tube allow to measure the current and the voltage in the rock with no
influence from the surface effects that may take place near the power electrodes.
The study was conducted on sandy-argillaceous rocks whose fractional struc-
ture was previously determined (see table 9.1}. The average grain size of series
I was h = 0.203 mm, and of series II, l2 = 0.186 mm; the variance for series I,
1
2
u~ ) = 0.122, for series II, u~ ) = 0.117; clay made up 11.07% for series I and
14.5% for series II of the total mass. Thus by the fractional structure, the speci-
fied media are averagely homogeneous (u~i) /li!:::! 0.6) and averagely mudded-out.

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