American Oil and Gas Reporter - February 2016 - 62

SpecialReport: Improved Oil Recovery

Advanced Fluids Key In IOR Economics
By Deepankar "Dee" Biswas
PLANO, TX.-The methods of oil extraction become more technically complex
and costly for each successive phase of a
producing reservoir's life cycle. By the
time a well reaches the tertiary recovery
phase, the operational objective shifts

62 THE AMERICAN OIL & GAS REPORTER

from optimizing reservoir pressures and
sweep efficiencies to altering the physics
of how oil is trapped within the rocks in
order to improve its extractability.
Most thermal, gas and chemical tertiary
recovery processes seek to decrease the
interfacial forces holding oil in pores
within the rock formation, and to modify

reservoir and oil properties to release oil
more easily.
Chemical flooding methods inject
polymer, surfactant and/or alkali formulations to modify reservoir and oil properties to release oil more easily, including
reducing the interfacial tension (IFT) between water and oil to release oil molecules
from pores within the rock formation, altering wettability, and decreasing the mobility ratio and viscosity difference between
water and oil phases. In conventional
reservoirs, implementing chemical flooding after primary and secondary production
phases typically recovers an additional
10-20 percent of reserves.
Despite the significant enhanced recovery potential, the capital costs, geologic
risks and long cycle times associated
with chemical EOR methods have understandably left operating companies
reluctant to invest in projects. However,
a new approach offers an alternative to
traditional chemical flooding with dramatically lower costs, risks and cycle
times. It takes advantage of an advanced
surfactant-solvent "nanofluid" derived
from citrus fruit that is a more effective,
nontoxic alternative to traditional surfactants.
This environmentally friendly surfactant-solvent system is a thermodynamically
stable and balanced combination of water,
naturally occurring solvent, an alcohol
co-solvent, and a nonionic surfactant that
appears optically isotropic and maintains
high contact efficiencies even at low concentrations of 0.1-0.5 percent by volume.
It has proven effective as an additive in a
variety of applications, including remediation, fracturing fluids, restimulation,
acidizing, and even drilling fluids. The
technology is showing promise in ongoing
field trials to increase production in
tertiary recovery applications at minimal
incremental cost.
In mature waterfloods with appreciable
residual oil, injecting the nanofluid additive
enhances incremental production by reducing IFT and altering wettability, as
well as by lowering oil viscosity for improved oil mobility by solvent partitioning
in in-situ oil. Moreover, in tertiary recovery
applications in fields already undergoing
water injection and approaching the economic limits of secondary recovery, the
method can demonstrate increased oil
production within only six to nine months,
American Oil and Gas Reporter - February 2016

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