Formation waters from the oil fields can be expected to contain low 

 levels of hydrocarbons, dissolved mineral salts, and traces of heavy metals. 

 A common rule of thumb of production of formation waters is that about one 

 barrel of water is discharged for each barrel of oil produced. Although legal 

 requirements call for removal of oil to a 30 ppm level, these waters will still 

 contain high concentrations of salts and metals. Most of the salts consist 

 of sodium and calcium chlorides and some sulfates and bromates. Since dilution 

 in the open ocean would be immediate, any increases in salinity or minerals 

 would not be detectable beyond a few hundred feet of the discharge point. 



More significant water quality degradation would occur from used drilling 

 mud discharged into the sea. Drilling muds consist of clays, barite, and 

 small amounts of organic and inorganic chemicals. The composition of the mud 

 is varied according to the specific drilling substrate requirements and each 

 drilling operation or company. Drilling mud from exploratory wells is con- 

 tinuously sampled for fossils and paleontological evidence indicating likely 

 oil-bearing formations. For this reason it cannot be recycled and is dis- 

 charged at the drill site. Production wells do allow for re-use of the mud; 

 about 10% is lost due to contact with drill cuttings, however. Discharge of 

 drilling muds is regulated by the Environmental Protection Agency, which may 

 limit such discharges if heavy metal levels approach toxic levels. When 

 drilling mud is added to sea water, the fine clays remain in suspension for 

 a considerable time. Associated with the clays are the metals and petroleum 

 hydrocarbons. Although some of these polluting substances will go into solu- 

 tion in the water column, the greatest portion will settle out with the clays 

 a few hundred (or thousand) yards from the platform. 



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