Six exploratory oil well drill sites were examined with a two-person submersible in water depths ranging from 21 to 149 m (70 to 490 ft). Time since wells were drilled ranged from 15 months to 17 years. The area of visually detectable cuttings around recently drilled wells in depths greater than 45 m (148 ft) ranged from -2,539 m2 (27,320 ft2) to -13,352 m 2 (143,668 ft2). At the shallowest site, the area with cuttings was only -20 m2 (215 ft2).. All visually observed impacts were mainly mechanical, such as debris, and anchor or jackup-leg scars. No lasting impact was observed at the 17-year-old site.
Public concern over offshore drilling, especially off California and south Florida, has risen steadily since the early 1970s. Although two National Academy of Sciences reports 1,2showed offshore drilling to be safer than tankerage, events such as the IXTOC- 1 blowout, the Exxon Valdez tanker spill, and more recently, the Persian Gulf wars have served to punctuate public concern. Political pressure, and public concern, exacerbated by a lack of credible environmental data and highlighted by a recent National Academy of Sciences panel review Report3 and a State of Florida Governor's Report,4 led to a drilling moratorium on the southwest Florida shelf.
The purpose of this paper is to present observations, made on the basis of direct underwater examination, of six exploratory well sites in the eastern Gulf of Mexico. The wells were drilled between 1972 and 1990. This study builds on an earlier study of five well sites off the Florida Keys, where wells were drilled between 1959 and 1961. That study also included two deep-water sites drilled in 1981 nd 1986. Both studies were funded by the Minerals Management Service (MMS) EnvironmentalStudies Program. The first study, conducted in 1988, has been published in the biological literature,5 as an MMS technical report,6 and was visually presented in a 21- minute video.7 Field work for the second study was conducted in November 1991, and a thorough analysis of the data and bottom samples that were collected is in progress.
Well sites in the 1991 study ranged in depth from 21 m (70 ft) to 149 m (489 ft), and the youngest site had been spudded only 15 months before our examination (Fig. 1, Table 1). The oldest site was drilled 17 years before our examination. Another site, Gainesville Block 707, had been the subject of an extensive pre-drilling assessment and monitoring study during drilling. 8 The results of those studies were rendered questionable when Hurricanes Danny (Aug. 16-16, 1985) and Elena (Aug. 31-Sept. 3, 1985) swept the bottom while the study was underway. Evidence of drilling impacts were for the most part destroyed, and the study was terminated. 9,10