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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