Application of Electrokinetics for Enhanced Oil Recovery - Electrokinetics for Petroleum and Environmental Engineers - page 140

3.12 Laboratory Measurements

The DCEOR demonstrations at oilfields in the Santa Maria Basin,
Lloydminster Heavy Oil Belt and Golfo San Jorge Basin all exhibited:

• Increased oil production

• Reduced water cut

• Increases in API gravity of the produced crude

Controlled laboratory tests were developed to further evaluate these
field results. Standard petroleum Special Core Analysis Laboratory (SCAL)
electrical and flow measurements involve small (1in diameter by 1 - 2 in
long) samples housed in Hasler Load Cells, for short term (hours to days)
tests. Using these types of tests for investigating the mechanisms involved
with DCEOR present the following problems:

• The weeks to months involved in the DCEOR field demon-
strations create considerable electrode reaction products at
the anodes and cathodes, which could overwhelm any reac-
tions occurring with in the standard petroleum SCAL test
sample.
• The very low (μV/m - mV/m) potential gradients involved
in the DCEOR field demonstrations are extremely difficult
to maintain in a laboratory environment.
• Synthetic surrogate reservoir formation, crude, and brine
samples often used for laboratory measurements may not be
representative of the actual reservoir material.

To overcome these test design problems, Electro-Petroleum, Inc. (EPI:
Wittle and Hill, 2006a and 2006b; Wittle 2008a, 2008b, 2008c, and 2011)
and P + P Geotechnik GmbH (P + P: Döring, 1993, 1996) used large (0.5 -
1.0 m 2 ) samples for laboratory testing.
Figure 3.25 and Table 3.7 describe the progress of a large-scale (~1 m 3
volume sample) laboratory test conducted on a California heavy oil field
reservoir rock, via Gas Chromatograph-Mass Spectroscopy analyses of
samples collected from the test sample at the start of the DCEOR test (red
curve of figure 3.25) and after 74 days (black curve of figure 3.25).
The more complex hydrocarbon molecule abundances (right end of
the figure 3.25 spectras) have been reduced, while the simpler molecule
abundances (left end of spectras) have increased, as a result of this 74-day