Volume 14, Issue 3 (May 1986)
A Preliminary Examination of the Laboratory Sheen Test
A proposed test procedure for detecting “free oil” in discharges of drilling fluids and cuttings from offshore oil and gas wells has been evaluated by the Environmental Protection Agency (EPA) and independently. Several preliminary examinations with small numbers of observers were performed, and later expanded by testing with 26 observers. The procedure, including recent modifications, appears to be relatively sensitive but of questionable usefulness as a monitoring tool. Results are highly variable, depending on the type of drilling mud, presence of interfering compounds, and sample size. Other factors (i.e., vibration, angle and type of light, sample age, and sample preparations) may also cause variable results and will need to be more carefully evaluated. The definition of sheen is expanded in the most recently proposed version of the procedure, causing more samples to fail than with previous definitions. It is suggested that the procedure be further evaluated.