Introduction to Electrokinetics - Electrokinetics for Petroleum and Environmental Engineers - page 14

Titkov et al. (1961) have introduced the idea of indurating weak rocks
in the wall of the borehole by electrochemical treatment. This is carried
out by the continued introduction of special electrolytic solution at the
anode during the electrical treatment. They have thoroughly investigated
the electrochemical treatment of different types of geological formations
using various combinations of electrolyte solutions. The investigation was
performed on a variety of formation samples in the laboratory, as well as
on specially selected field sites. In addition, they tested the use of different
electrode material, such as aluminum, iron, and carbon.
Electrochemical induration of weak rocks is dependent on the formation
of a new and stronger authigenic cementing material. The formation of new
minerals (gibbsite, allophane, aluminite, limonite, hisingerite, calcite and
gypsum) were reported (Titkov et al. 1961) to have occurred during elec-
trochemical treatment. Cylindrical movable electrodes with variable diam-
eters were designed by Titkov et al. (1961) in order to test this treatment in
the wall of drillholes. With stationary or circulating fluid, it was possible
to obtain favorable results in indurating the walls of drillholes for different
lengths of time at varying depths from 10 to 116 m. The circulating fluid was
varied from pure electrolytic solution to a chemically treated clay-cement
mixture. On the basis of tests carried out 13 months later, on the electro-
chemically indurated drillholes, Titkov et al. (1961) concluded that:
1. The suitability of the electrochemical treatment of weak
rocks is quite promising not only at the time of drilling, but
also during well exploitation.
2. The walls of a drill-hole may be indurated electrochemically
either by the creation of a crust of hardened mixture consist-
ing of clay or loam and binding materials such as cement;
or by increasing the stability of clay rocks by transforming
them through the electrical action.
3. Reversing the electrodes' polarity during electrochemical
treatment will speed up the cementing process.
4. The electrochemical induration of weak rocks is certainly an
irreversible process.
1.7 Bioelectroremediation
There is a wide variety of mechanical, physical, chemical, and bioremedia-
tion cleaning methods that are applied in contemporary practice for the
restoration of contaminated sites. It is even difficult to name all of them