A review of the performance of the Phillips North Burbank micellar-polymer flood has been completed. The projected ultimate recovery is estimated to be ca 300,000 bbl, which is approximately one-half of the initial prediction made by Phillips. Although oil recovery has been less than expected, sufficient additional oil has been recovered to consider the project technically successful. The lower-than-expected oil recovery is attributed principally to high sulfonate losses. Loss of the sulfonate appears to be the result of significant adsorption to the oil-wet pore surfaces and mixing of micellar fluids with in-place water, which is of high salinity and hardness. Contact of the sulfonate with the high concentration of calcium ions creates calcium sulfonate, which either precipitates as an insoluble phase or partitions into the oil phase. Sulfonate partitioning would have created an upper-phase microemulsion, which cannot be displaced easily by water due to the relatively high interfacial tension. 11 references.