discharge of drilling muds appears related to coral reefs sited near 

 drilling operations. Increased turbidity (decreasing light availability 

 to coral zooxanthellae) and the remote possibility of direct smothering 

 of the coral have been viewed as major concerns. Response to these 

 concerns has been to require shunting of turbid drilling fluids to 

 within 10 m of the bottom in areas near coral reefs which puts the 

 fluids into the near-bottom turbid layer. The assimilative capacity of 

 the Texas-Louisiana shelf ecosystem with respect to drilling muds (how 

 much can be discharged before a measurable system-level effect threshold 

 is reached) has not been addressed by any study. However, if 

 development of the shelf proceeds as planned over the next decade, an 

 average of 67»000 tons of mud solids a year will be discharged, 

 approximately 0.02$ of the amount of solids contributed annually by the 

 Mississippi River (Department of the Interior/Bureau of Land Management, 

 DOI/BLM 1981). 



PRODUCED FORMATION WATER 



The major effluent emanating from petroleum production platforms in 

 the gulf is the briny water from the formation which is separated from 

 the hydrocarbon products (oil, condensate, gas). The volume of this 

 discharge varies considerably among formations and over time. An 

 actively producing gas and oil production platform investigated during 

 1976-80 offshore of Texas averaged between 1,000 and 1,400 bbl/day 

 (about 2. 5 A' sec) discharge (Gallaway et al. 1980). Produced formation 

 waters typically contain high concentrations of dissolved inorganic 

 salts in which the principal cations are sodium, magnesium and calcium 

 with chloride, sulfate, carbonate and bicarbonate being the principal 

 anions. Concentrations of total dissolved constituents range up to 

 350,000 mg/£. Hydrocarbons and other organic compounds are present in 

 produced waters at parts per million levels. Dissolved oxygen levels 

 are low at best (usually anoxic) and temperature of produced waters is 

 high (30° to 40°C). Collectively, produced water and minor spills have 

 been estimated to account for 2$ of the six million metric tons per year 

 of hydrocarbons discharged to the oceans (National Academy of Sciences 

 1975). 



The nature and effects of produced water discharge were recently 

 investigated at a gas and oil field offshore of Galveston, Texas. 

 Produced waters were characterized in terms of alkanes, aroma tics, 

 volatiles, sulfur, and biocides by Middleditch and West (1980). They 

 estimated the daily discharge of alkanes to average 382 g in produced 

 waters, which represented 19$ of the estimated 2 kg/day total of oil 

 discharged from BG0F production platforms. The light aromatic fraction 

 of hydrocarbons in produced water was represented by some 68 different 

 compounds having an average total concentration of 104.2 parts per 

 billion (ppb). Twelve normal, branched and cyclic alkanes were 

 characterized in the analysis of produced water volatiles. Three 

 aromatics, comprising 64$ of the volatile components measured, were 

 identified as benzene, toluene, and ethylbenzene. 



58 



