While conventional bulk foam stability tests were typically used for surfactant selection, the researchers observed homogeneity in the generated foam. To address this issue, they modified the test by adding quartz river sand at the base of the column, which created a more heterogeneous foam texture. The study concluded that all three screening methods consistently assessed the impact of surfactant concentration on foaming. Despite yielding different salinity results in standard bulk tests, they effectively identified very low-performing samples. Bulk tests with modified sand yielded results similar to those of sandpack tests, suggesting that the improved performance may be attributed to the sand inducing a more heterogeneous foam texture.