Tracing the Fate of Petroleum Drilling Fluids in the Northwest Gulf of Mexico

Discharge of spent drilling fluids in the NW Gulf of Mexico has received much attention as operations move close to the coral reefs of the Texas Flower Garden Banks. Our study has addressed the problem of identifying and tracking drilling fluid components which have been discharged into the marine environment and evaluating the degree to which these components have impacted the area. Using sea-going clean lab techniques, suspended matter Ba concentrations have proven to be a sensitive indicator of dispersion pathways. Particulate Ba distribution has enabled us to:1)identify rapid differential settling of much, but not all, of the Ba relative to other constituents upon discharge, 2)note that BaSO₄-rich deposits, common in the sediments near a rig, are less susceptible to resuspension than normal aluminosilicate detritus and 3) distinguish normal water column particle-rich layers from drilling related lenses. At present, we find no evidence of the occurrence of drilling fluid components on the Flower Gardens, however, a several fold, non-problematic increase in suspended Ba occurs in the northern rig area.