Page 74 - Formation Damage during Improved Oil Recovery Fundamentals and Applications

56 David A. Wood and Bin Yuan

2.11 POTENTIAL TO COMBINE LSWF WITH OTHER IOR
MECHANISMS
There is significant potential to combine LSWF with other IOR
technologies at it works to complement and enhance several other EOR
methods in the form of hybrid processes. However, formation damage
mechanisms are also more complex in terms of potential causes and
effects.

2.11.1 LSWF combined with surfactants
Skauge et al. (2011) reported the results for core-flood experiments for
the Berea sandstone and simulation models involving LSW combined
with surfactant flooding. The concept behind this combination of IOR
methods (Alagic and Skauge,2010) is that some of the discontinuous oil
that is potentially mobilized by LSWF is likely to be retrapped in the
reservoir at the given capillary pressure. By also injecting surfactant, the
capillary pressure in the swept reservoir should be further reduced, and
retrapping of mobilized oil should be reduced.
Wettability alteration was assumed to be the main LSWF mechanism
at work in the developed simulation models, although the authors recog-
nized that other factors were also probably influencing reservoir behavior.
Nevertheless, the simplified models built on two different simulation
software packages developed salinity dependent oil and water capillary
pressure and relative permeability curves, which successfully matched oil
recovery and differential pressure from the core-flood experiments with
salinity change. Skauge et al. (2011) concluded that surfactant flooding at
low salinity produced better than expected results in terms of reduction
of IFT and capillary number.

2.11.2 LSWF combined with polymers
Shiran and Skauge (2013) evaluated the synergistic effect on residual oil
mobilization and final oil recovery of combining LSWF with polymer
injection and, based on Berea sandstone core experiments, whether this
worked better in secondary or tertiary recovery modes. The concept is to
enhance LSWF with the benefits of polymer flooding that involves the
addition of large molecular weight, water-soluble polymers, and linked
polymer solutions to injection water to increase the viscosity of displacing
fluid and improve the adverse mobility ratio. The wettability of the