Smart Surfactants
The Smart Surfactant system (U.S. patent number 7373977)
is a one-component system that provides low interfacial
tension and proper viscosity. Mixtures of surfactants
can be employed to selectively block reservoir channels
containing water and allow the surfactant(s) to penetrate
channels containing oil and mobilize the oil by lowering
interfacial tension.
The advantages of using the Smart Surfactant System
include:
- One component system to provide low interfacial
tension and proper viscosity
- No residue
- Does not cause polymer blocking
- Tolerant to salts and divalent cations
- No water treatment is required
- Minimal surface equipment required
- Minimal up-front investment
- No polymer dissolving or hydration units required
Water Flood
In general, water flood can remove an additional ~
10 - 30% residual oil after primary recovery. Extensive
water flooding causes water channels though the most
permeable area and causes premature water break-through,
leaving many oil containing areas untouched.
Surfactant Flood
After the water channels are formed, if only surfactant
is used for the flood, without any profile control,
most likely the surfactant flood will follow the existing
water channels in the formation and still leave many
oil containing areas un-touched. Because the sweep efficiency
is not optimized the oil recovered using this tertiary
recovery process is often disappointing.
Smart Surfactant
The Smart Surfactant system provides both
low interfacial tension between the injection water
and residual oil and the viscosity necessary for profile
control. It selectively blocks the water channels, seeks
out the remaining oil-bearing sections of the formation
that were untouched by the water flood, lowers the interfacial
tension and mobilizes the residual oil to further increase
the oil production.
The process using Smart Surfactants can be repeated
through several cycles by injecting a fraction of a
pore volume, i.e. 0.1 PV, followed by injection of water
until no oil is produced as shown below. The cycle is
then repeated with another fractional pore volume until
the amount of oil produced is not economical to continue.
In the example shown below four injections of 0.1 PV
each were made at points A, B,C and D.
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