Evaluation of Overall Marine Impact of the Novadril Mud Systems
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- NIVA-rapport 
The recent increase of discharges of synthetic drilling fluids from offshore drilling operations have caused environmental concern with regard to possible effects on benthic ecosystems. The present report is a review of available data on toxicity, bioaccumulation and biodegradation of the Novadril polya-a-olefin based mud systems as compared to alternative mud systems. Attention was focused on biodegradable with half-lifes of 368 and 207 days, respectively. The latter halflife of Petrofree esters. No severe effects have been observed on pH and redox potential in experimental sediments trated with bore hole cuttings contaminated with these muds. From the scarce information avaible. Novasol III is expected to be a more easily degradable base fluid. No data has yet been made available to assess any change o toxicity and bioaccumulation potential of the modified base fluid.