Discharged drilling waste from oil and gas platforms and its effects on benthic communities

Abstract

This review paper identifies the main effects of oil and gas drilling waste on benthic environments. We identified 26 papers and technical reports that surveyed sediment samples from 72 production or exploration platform sites to assess the zone of influence of sediment contamination and biological effects on benthic communities. While oil-based fluids are now rarely used in the marine context, their release has had large-scale (out to 6 km) and persistent (decadal time scale) impacts on benthic communities. The zone of influence of water-based drilling fluids as determined by sediment barium concentration was larger (2 to 20 km) than for synthetic-based fluids (200 to 2000 m). The zone of biological effects on benthic community diversity and abundance ranged from 100 to 1000 m for both water and synthetic fluids. Effects include changes in benthic species diversity, abundance and alterations to community structure. Functional changes included a loss of suspension-feeding species and increases in deposit feeders and polychaetes. In general, this review demonstrates a loss of benthic biodiversity and suspension-feeding communities due to oil exploration and production and the potential for large-scale effects on sensitive communities such as deep-sea, coral and vegetated habitats. Current research gaps and priorities are identified.KEY WORDS: Benthic community composition · Chemical toxicity · Organic enrichment · Suspended sediments · Oil-based fluids · Synthetic-based fluids · Water-based fluids Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 456: [285][286][287][288][289][290][291][292][293][294][295][296][297][298][299][300][301][302] 2012 charged directly at sea. The third step includes the installation of a blow-out preventer on top of the wellhead which controls formation pressures. Additionally, a marine riser is installed that allows all drilling fluids and cuttings to be pumped up through the riser and back to the oil platform or drilling ship. The remaining sections of the well are then drilled to reach the oil reserve.Drill cuttings are produced by the grinding action of the drill bit and range in size from clay-sized particles to coarse gravel, having a mineralogy reflecting that of the drilled strata (Neff 1987, 2005, Trannum et al. 2010. Drilling muds lubricate the drill string, bring up cuttings from the well hole, control internal pressure and stabilize the well and constitute 5 to 25% of the discharged drill fluids (Trannum et al. 2010).There are 3 main types of drilling mud: oil-based, synthetic and water-based fluids (OBF, SBF, WBF). In oil-based mud, the dominant fluid is a mineral oil; in synthetic mud it is ester, ether, acetyl or olefin; and in water-based mud, fresh or salt water is used. Drilling muds also contain a weighting material, clay or an organic polymer, various inorganic salts, solids and organic additives (Neff 2005). Barite (BaSO 4 ) has been the most frequently used weighting material. More recently, ilmenite (FeTi...

Ecological Role of Submarine Canyons and Need for Canyon Conservation: A Review

“…However, other studies indicate that the effects of elements incorporated in discharge are mainly a physical stress, while chemical toxicity is not always described (Bakke et al, 2013). Although studies specific to submarine canyons have not been conducted, the effects of drilling waste on benthic and demersal species is highly dependent on a number of local environmental variables (e.g., depth, current, and wave regimes, substrate type; Ellis et al, 2012). Thus, it is expected that similar or even greater effects in canyons because of the presence of VMEs (e.g., coral reefs) and potentially restricted movement of pollutants due to current regimes in canyons.…”

“…Over the last 10 years, several studies have focused on the effects of exploratory offshore drilling in response to the growing interest by the oil and gas industry to move operations further offshore (Currie and Isaacs, 2005;Ellis et al, 2012;Bakke et al, 2013;Paine et al, 2014). This offshore shift is especially true for countries such as the United Kingdom, Norway, Italy, Malaysia, Indonesia, and Australia, which number among the leading oil-producing countries (Patin, 1999).…”

“…Drilling discharges are composed primarily of dense particulate solids that settle rapidly and accumulate in sediments down-current from the platform (Bakke et al, 2013). The rapid accumulation of these solids in the sediments has caused changes in benthic community composition (loss of rare species and increase in abundance of pollution tolerant species), decrease in abundances and diversity of communities and decrease in coral coverage among others (reviewed in Ellis et al, 2012). The effects of drilling discharge can also affect the biology, particularly growth and reproduction, of megafaunal species.…”

Towards enhancing sustainable reuse of pre-treated drill cuttings for construction purposes by near-infrared analysis: A review

“…The ecological effects of drill cuttings when disposed of on land or sea without prior treatment have been widely documented in the open access literature (Ellis et al, 2012;Zamora-Ledezma and García, 2013;Larsson et al, 2013;Durgut et al, 2015;Nilssen et al, 2015). In a recent review, Ellis et al (2012) revealed a loss of benthic biodiversity and suspension-feeding communities due to discharge of drilling waste from oil and gas platforms.…”

“…In a recent review, Ellis et al (2012) revealed a loss of benthic biodiversity and suspension-feeding communities due to discharge of drilling waste from oil and gas platforms. Zamora- Ledezma and García (2013) reported that drill cuttings are extremely toxic for some species of tropical grasses including Urochloa decumbens and Urochloa maxima.…”