Environmental Engineering Reference
In-Depth Information
Figure 3.21 DCEOR simulation results: Comparison of AC and DC electrical power loss
for various casing depths (after Wittle and Hill, 2006; Wittle et al., 2008a, 2008b, 2008c)
For AC electrical current , however, they also depend upon capacitive and
inductive losses . Capacitive loss, in DCEOR, usually involves current leak-
age to the formation and is generally not a significant concern. Inductive
losses for AC signals, however, can become considerable, because of induc-
tive coupling to the earth, from the long cables and/or casing between the
generators, at the surface, and the downhole and/or surface electrodes.
Figure 3.21 compares DC and 60 Hz AC power losses for different trans-
mission line current strengths and well depths, using a common vertical
(power loss) scale. All of the DC currents (up to 500 A) fall along the hori-
zontal axis of figure 3.21, with insignificant power loss, even to depths of
10,000 ft. By contrast, for a 10,000 ft. well, the 60 Hz 500 A system power
loss is over 850 kW. Higher frequencies would fare even worse. This is
the reason why AC heating has not been very successful, except for very
shallow reservoirs, and extremely short electrode spacings.
3.10
DCEOR Field Demonstrations
Multiple DCEOR field demonstrations have been conducted at heavy oil
fields in the Santa Maria Basin of California (USA), Lloydminster Heavy
Oil Belt of Alberta and Saskatchewan (Canada), and Golfo San Jorge Basin
of Santa Cruz (Argentina).
 
Search WWH ::




Custom Search