Caustic steam flooding

A laboratory study was undertaken to investigate the potential of improving tertiary oil recovery of intermediate to heavy oils by use of caustic soda as a chemical additive in waterflooding and steamflooding. Seven aspects of this study were examined. In all cases, the process was started with a fresh and similarly waterand oil-saturated sandpack. The sandpack was obtained each time by packing sieved glass beads in the range of 35 to 48 mesh size. The cases include: (1) weak caustic soda flooding (0.001 g/cm/sup 3/) of previously waterflooded sandpack followed by steamflood, (2) caustic steamflooding immediately after waterflooding the saturated sandpack, (3) a process similar to Case 2 followed by a second cycle flooding with a higher concentration (0.0015 g/cm/sup 3/) of caustic steam, (4) waterflooding a saturated sandpack followed by conventional steamflood, (5) caustic flooding of water-saturated sandpack followed by caustic steamflood, (6) cyclic steam/caustic flooding of watersaturated sandpack, and (7) determination of the optimal temperature for caustic flood. The results of these experiments showed that as a chemical additive for tertiary waterflooding and steamflooding, caustic soda substantially improved oil recovery of mildly acidic 18/sup 0/API gravity oil over conventional waterflood and steamflood.