In a follow-up evaluation to the Phillips-DOE surfactant-polymer pilot in the North Burbank field of Osage County, Oklahoma, a test program was designed to determine the relative importance of the various detrimental factors - heterogeneity, crossflow, ion exchange, partitioning - leading to nonconformance, and degradation of surfactant and polymer slugs. A diagnostic well was drilled 80 ft (24m) southeast of an injection well, within the drainage area of one of the best producing wells for tertiary oil. The location was selected because: (1) there was good communication between the injector and producer in this quadrant, (2) it was one sixth of the distance between injector and producer, and should likely be swept by injected chemicals, and (3) simulation suggested that a well at this location could encounter several zones swept by surfactant, polymer, and fresh water. Rock, brine, and oil samples were taken from three noncommunicating reservoir zones and analyzed for sulfonate, polyacrylamide, alcohol, calcium, and residual oil, along with a complete brine analysis. Comparisons were made with core analyses on adjacent wells at the start of the project, and with fluids produced from them. Chloride and residual oil were low, indicating that the region had been swept and oil displaced. Sulfonate and alcohol were surprisingly high. At a sweep of less than 5% of the area, surfactant and cosurfactant were segregated, and the slug was markedly displaced toward the Type II/sup / direction from optimality. No polyacrylamide was detected in the brine or on the rock. These observations indicate that the performance of the pilot was influenced by both heterogeneity and degradation of the chemical slug. The relative role of the polymer is still uncertain. 19 refs., 14 figs., 14 tabs.