An environmental study to assess the impact of drilling discharges in the Mid-Atlantic. I. Quantity and fate of discharges

Abstract

From the Abstract: “This report covers one facet of an environmental monitoring study on an offshore exploratory well in the Mid-Atlantic; of which the overall objective was to determine the effect of drilling discharges on ambient water quality, bottom sediments, and the benthic community. The environment was monitored around the well site before the rig moved on location (Pre-Drilling Phase), while the rig was on location (Drilling Phase), and after the rig moved off location (Post-Drilling Phase).

The well was located approximately 156 km east of Atlantic City, New Jersey in a approximate water depth of 120 meters. The drilling phase of the program lasted from early January until mid-July 1979. During this time 752 metric tons of barite, 1,409 metric tons of low gravity solids and 94 metric tons of organic chemical were discharged. Approximately 60–70% of these discharges were carried away from the rig in a south-south-westerly direction by the prevailing currents.The source of most trace metals in the discharges was the formation of drill solids. Some mud additives contributed to chromium, zinc, and possibly lead concentrations in the discharges…Suspended solids and transmittance were the only two parameters affected by the discharges. In both tests suspended solids concentrations reached background levels before the plume had drifted 600 meters from the discharge source.”