Abstract: Oil production from a fractured, oil-bearing subterranean formation is enhanced by sequentially injecting (i) a wettability reversal agent-containing fluid and (ii) an overflush fluid through a well and into the formation. The well is then place into production after allowing a sufficient period of time for (a) the matrix face of the formation to change from preferentially oil wet to preferentially water wet and (b) a displacing fluid (e.g., hot water, steam) to imbibe into the fractured matrix and displace the oil from the matrix into the fracture cracks.

Abstract: The time delay experienced between the commencement of the steam-foam drive and the subsequent incremental increase in oil production rate is reduced by simultaneously (a) injecting steam into the lower level of a subterranean oil-bearing formation and (b) injecting foam into the upper elevation of the formation. Preferably, the elevation where the foam is injected is gradually lowered while maintaining the steam injection elevation substantially constant. The accelerated response rate improves the economics of the steam-foam drive.