Biological effects of drilling fluids, drill cuttings and produced waters

Abstract

This paper summarizes the literature on the effects of drilling fluids, drill cuttings and produced waters emitted from oil and gas platforms. From the Conclusions: 1) Drilling fluids are diluted rapidly in the water column to suspended solids concentrations of 1000 ppm within two minutes and below 10 ppm above background levels with one hour of discharge…2) Most of the major ingredients of drilling fluids have a low toxicity to marine organisms. Only chrome and ferrochrome lignosulfonates and sodium hydroxide are slightly toxic…3) Acute lethal toxicity of more than 70 used water-based drilling fluids has been evaluated in more than 400 bioassays with at leat 62 species of marine organisms from the Atlantic and Pacific oceans, the Gulf of Mexico and Beaufort Sea. Nearly 90% of LC50 values were above 10,000 ppm drilling mud added, indicating that the drilling muds were practically nontoxic…4) Chronic and/or sublethal effects of drilling fluids have been performed with at least 40 species of marine animals. In most cases, sublethal responses in marine animals were observed at drilling mud concentrations only slightly lower than those that were acutely lethal...Practically no laboratory studies have been performed on the sublethal or chronic effects of produced water in marine organisms…6) In experimental field studies, accumulation of petroleum hydrocarbons has been demonstrated from produced water but not from drilling fluids…”