Oil recovery in fractured oil reservoirs by low IFT imbibition process
This paper presents the results of an experimental study performed to investigate the effect of reduced interfacial tension (IFT) on oil recovery by spontaneous imbibition and gravity segregation. The results of the static imbibition experiments, in which a matrix block was surrounded by the imbibing fluid, showed that a minimum Bond number (NB{sup -1}) was required to increase the final oil recovery. However, the reduction of the IFT may increase or decrease the rate of imbibition substantially depending on the relative contribution of capillary and gravity forces. The results of the experiments performed on three ranges of permeabilities with four different surfactant solutions (different IFT values) showed that imbibition can occur in three different regimes: capillary dominated, gravity dominated, and a regime in which both forces affect the imbibition process. In order to examine the effect of IFT on oil recovery on the same core, core wettability has to be restored after each test. Several cleaning procedures were investigated to reproduce original core wettability. As an outgrowth of this research, a core cleaning technique for restoring core wettability has been suggested. Firing the core after toluene cleaning for seven hours at 9500 F was found to be an effective procedure to restore core wettability after solvent extraction. The same procedure also proved effective for restoring the original core wettability after surfactant solution imbibition tests.
- OSTI ID:
- 468116
- Report Number(s):
- CONF-961003--
- Country of Publication:
- United States
- Language:
- English
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