Environmental Engineering Reference
In-Depth Information
various countermeasures are employed to prevent the differential sticking
(Brandon et al., 1993).
Khasaev et al. (1983) showed that DC current can reduce the release-
torque. Current densities of 0.7-14.4 mA/cm 2 reduced the release torque by
50 % after 0.5-2.5 hours. This was probably due to electrokinetic transport
of water to the drillstring-mudcake interface (cathode).
In the laboratory, Bonanos et al. (1993) showed that for polymer-based
drilling fluids, the torque required to free the discs decreased by 50-70% on
passing 10 mA/cm 2 DC current. Brandon et al. (1993) conducted excellent
research on the effect of cathodic currents on friction and stuck pipe release
in water-based drilling fluids. They found that the release-torque was
reduced by 50 % in polymer-based and 80 % in clay-based drilling fluids.
1.12 Summary
One can summarize the major features and advantages of electrokinetic
technology as follows:
• The flow rate of oil and water can be increased by the appli-
cation of direct current.
• Chemical additives may be used in conjunction with elec-
trical treatment to augment the flow rate of transportable
fluids.
• Electrochemical treatment may be used for well stimulation.
• Electrokinetic flow rate increases with increasing potential
gradient (or electrical current, I ), first reaching a maximum,
then decreasing with further increase in electrical current.
• It is cost competitive with steam EOR, with no depth
constraint.
Thief zone problems (e.g., in the case of steam injection in
EOR) do not exist.
There is no water or working fluid requirement.
Reduces water consumption and water cut when compared
to steam EOR.
No hazardous emissions or liquid problems.
Facility installation can be incremental, allowing the spread-
ing of capital over the lifetime of the desired projects.
DC current can be effectively applied for releasing the stuck
drillpipe in aqueous drilling fluids.
 
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