Application of Electrokinetics for Enhanced Oil Recovery - Electrokinetics for Petroleum and Environmental Engineers - page 105

heavy oil reservoirs. Steam assisted recovery has also been utilized as a
finishing technique for lighter oil reservoirs (Blevins et al., 1984).
Steam assisted oil recovery, however, may not always be an option. The
maximum depth for steam extraction has been increasing but the practical
limit still appears to be between 2,000 and 2,500 ft. Deeper unrecovered
oil resources require alternative technologies. Many reservoirs also contain
reactive matrix minerals, which can cause irreversible reservoir damage
from steam recovery technologies.
Steam assisted oil recovery may also not be appropriate for very shal-
low resources (e.g., less than 500 ft.), because of the potential danger of
steam breakthrough to the surface (Staff, 2011). Finally, steam assisted oil
recovery may face environmental hurdles, in areas where water is in short
supply, waste water disposal is a problem, and/or steam generators, com-
pressors, and pumps require air permits.
Direct Current (DC) Electrokinetically Enhanced Oil Recovery
(DCEOR) may be a viable alternative to steam assisted oil recovery because:

• It is operational outside of the above steam assisted oil recov-

ery depth windows

• It has a negligible water demand

• It generates no waste-water streams, beyond that of normal

water cut

• It appears to actually reduce water cut, below primary recov-

ery levels

• It has a negligible to positive impact on reactive minerals

• It may actually clear pore throats of colloidal and fine grained

particles

• It has negligible air quality impacts

• It may also reduce the production of noxious and toxic gases,

such as H 2 S

3.2 Petroleum Reservoirs, Properties, Reserves,

and Recoveries

Before discussing Electrokinetically Enhanced Oil Recovery, we need to
briefly review petroleum reservoirs, reserves, and multi-phase saturation,
as well as primary, secondary, and enhanced recovery. This background is
needed to better understand the impact of direct electrical current on oil
production.