A novel mechanism
of residual oil reduction during low-salinity
water flooding by induced fines migration and consequent permeability
damage is discovered. Dry corefloods (without oil) with piecewise-constant
decreasing salinity are conducted to verify the presence of movable
fines that yield permeability decrease. Sequential two-phase coreflood
tests are performed using the displacement of nonpolar oil by high-salinity
water, followed by full resaturation of the core by nonpolar oil and
low-salinity waterflooding. The test then continued in tertiary mode,
in which brines of decreasing salinity were injected in the presence
of residual oil. Four Berea cores with high clay content, one Bentheimer
core with low clay content, and two artificial cores with no clay
content were used for two-phase waterflooding experiments. Reduction
in permeability for water, fines production, and reduction in residual
oil saturation accompanied the abrupt salinity decrease in all tests.
This effect is attributed to fines mobilization that is due to salinity
decrease, followed by fines migration and straining in thin pore throats
that resulted in local hydraulic resistance and consequent pore-scale
flux diversion, yielding S
or reduction.
The S
or dependencies of the induced formation
damage are derived from five series of laboratory tests. All the laboratory
tests confirmed the proposed S
or reduction
mechanism by fines-assisted low-salinity waterflooding.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.