seawater levels but all the constituents of produced water are diluted very 

 rapidly and would pose no problem in a canyon 1 km from the source. Even in a 

 worst-case situation in shallow water in the Gulf of Mexico over a period of 

 several years there is very little evidence of any effect of hydrocarbons from 

 normal drilling and production operations. The same is true of 

 radionuclides--there is some radium (radium-226 and -224) in produced water, 

 but there is little signal beyond the immediate discharge site. 

 Bioaccumulation of radium is possible, but there is no evidence to date 

 suggesting that it has occurred. 



Amounts of produced water are highly variable; the average per platform 

 in the Gulf of Mexico is around 2,000 bbl/day. Volume increases with the age 

 of the well. There is little produced water associated with gas production. 

 A calculation illustrates the small effect of the produced water. At 50 ppm X 

 2,000 bbls/day, 15 L of oil and grease are discharged daily in the produced 

 water. 



Physical Obstructions 



Anchors could be used to secure a semi-submersible drilling platform 

 during exploration; for production, bottom-mounted rigs with no anchors would 

 be used. Anchors could extend radially up to 1 mi from the platform, but 

 there would be no need to locate one close to a canyon rim. Anchor impact on 

 the bottom is small. It was estimated that even if full production were to 

 take place on Georges Bank there would be no more than 30 platforms*--the 

 number in the much more productive North Sea. Current shear like that found 

 at the shelf edge, even with warm-core rings, would not present an engineering 

 problem for drilling given the expected water depths. 



'See also reviewer comment in Appendix A. 



101 



