Page 346 - Enhanced Oil Recovery in Shale and Tight Reservoirs

Forced imbibition 319

Figure 11.10 Oil saturation at 0.4 days (A) and 9 days (B) in the case of alkali injection
only (shale rock).

sides of the fracture are uniformly distributed, indicating the alkaline solu-
tion enters the matrix uniformly by imbibition. And the oil saturation
near the fractures is reduced, indicating that countercurrent flow of alkaline
solution and oil occurs. Comparing to Fig. 11.9 for the surfactant injection
only, the oil production in the alkali injection only is later, because the imbi-
bition needs some time to effectively displace oil. The results from this
model seem to indicate that wettability alteration is more effective than
IFT reduction.