Page 332 - Enhanced Oil Recovery in Shale and Tight Reservoirs

Spontaneous imbibition 305

Figure 10.16 T 2 spectrum curves in initially saturated cores before and after sponta-
neous imbibition of heavy water and four surfactant solutions.

(NaBO 2 $4H 2 O) was added to generate soap (in situ generated surfactant), so
that this soap may have a synergy with a synthetic surfactant, and alkali may
reduce surfactant adsorption. These mechanisms are discussed in Sheng
(2011) for alkali-surfactant flooding. Alkali may also change wettability
(Johnson, 1976). For Bakken cores aged with Bakken crude with high resin
content, Nguyen et al. (2014) found increase in alkali decreased oil recovery