ENVIRONMENTAL STUDY TO ASSESS THE EFFECT OF DRILLING FLUIDS ON WATER QUALITY PARAMETERS DURING HIGH RATE, HIGH VOLUME DISCHARGES TO THE OCEAN.

Results are presented from a drilling fluid dispersion study which was conducted to determine mud component concentrations in the water column during high volume, high rate mud discharges representative of the type that normally occur when the drilling of the well is completed. In two discharge tests, 250 barrels of mud were discharged at a rate of 275 bbl/hr, and 389 barrels of mud were discharged at a rate of 1000 bbl/hr. The mud was a chrome lignosulfonate-clay type having a bulk density of 2. 09 g/cc (17. 4 ppg). A novel sampling technique allowed rapid and almost continuous sampling of the plume. During both discharges the mud formed two plumes, a lower plume and an upper plume. As the lower plume descended an upper, near surface plume was generated by turbulent mixing of the lower plume with seawater.