TEMPERATURE EFFECTS ON LOW TENSION SURFACTANT FLOOD EFFICIENCY IN CONSOLIDATED SANDS.

In low tension flooding the surfactant reduces the interfacial tension and alters the capillary number sufficiently to detrap substantially the residual oil in porous media. The authors are interested in low concentration processes involving small weight fractions of chemical in the injection phase. Several flooding experiments have been performed with Berea sandstones that are 2 inches in diameter and 10 inches long. The surfactants studied to data are Witco TRS 10-80 and Petrostep 465, both of which are anionic. Surfactant concentration is 2. 5 g/L in 10 g/L sodium chloride solution. Flood temperatures are 77 degree F, 180 degree F and 350 degree F (25 degree C, 82 degree C and 177 degree C). Also reported are floods in which surfactant is used as the primary injection fluid so as to compare this mode of injection with other sequences. Recoveries observed range from 44% at room temperature to 93% of original oil in place at 350 degree F (177 degree C) with TRS 10-80 and from 55% to 98% with Petrostep 465.