The environmental effects of offshore drilling

Offshore drilling and pollution
Offshore drilling and pollution

Quick bibliography: Reviews/recent articles on the environmental effects of offshore drilling.

Classic review:

*Menzie, C.A. (1982). The environmental implications of offshore oil and gas activities. Environmental Science & Technology16 (8), 454-472. [Cited by]

“The purpose of this article is to review the existing literature concerning the environmental fate and effects of routine discharges associated with offshore operations in order to better identify what parameters should be looked at for the purpose of monitoring. The review focuses on studies that have been preformed around various drilling or production platforms as well as laboratory studies that examined the toxic effects of discharges. A general review of these studies is expected to provide information that is useful for the design of future monitoring programs. The first section of this article summarizes the various quantities and types of discharges associated with offshore oil and gas operations and the monitoring requirements associated with each type of discharge. Various laboratory studies of these discharges or particular components are reviewed followed by a review of field studies. The final section of this article considers the implication of these studies in terms of future monitoring purposes.”

Recent reviews/articles:

*Cordes, E. E., Jones, D. O. B., Schlacher, T. A., Amon, D. J., Bernardino, A. F., Brooke, S., . . . Witte, U. (2016). Environmental impacts of the deep-water oil and gas industry: A review to guide management strategies. Frontiers in Environmental Science. [PDF] [Cited by]

“The industrialization of the deep sea is expanding worldwide. Increasing oil and gas exploration activities in the absence of sufficient baseline data in deep-sea ecosystems has made environmental management challenging. Here, we review the types of activities that are associated with global offshore oil and gas development in water depths over 200 m, the typical impacts of these activities, some of the more extreme impacts of accidental oil and gas releases, and the current state of management in the major regions of offshore industrial activity including 18 exclusive economic zones. Direct impacts of infrastructure installation, including sediment resuspension and burial by seafloor anchors and pipelines, are typically restricted to a radius of ~100 m on from the installation on the seafloor. Discharges of water-based and low-toxicity oil-based drilling muds and produced water can extend over 2 km, while the ecological impacts at the population and community levels on the seafloor are most commonly on the order of 200–300 m from their source. These impacts may persist in the deep sea for many years and likely longer for its more fragile ecosystems, such as cold-water corals. This synthesis of information provides the basis for a series of recommendations for the management of offshore oil and gas development. An effective management strategy, aimed at minimizing risk of significant environmental harm, will typically encompass regulations of the activity itself (e.g., discharge practices, materials used), combined with spatial (e.g., avoidance rules and marine protected areas), and temporal measures (e.g., restricted activities during peak reproductive periods). Spatial management measures that encompass representatives of all of the regional deep-sea community types is important in this context. Implementation of these management strategies should consider minimum buffer zones to displace industrial activity beyond the range of typical impacts: at least 2 km from any discharge points and surface infrastructure and 200 m from seafloor infrastructure with no expected discharges. Although managing natural resources is, arguably, more challenging in deep-water environments, inclusion of these proven conservation tools contributes to robust environmental management strategies for oil and gas extraction in the deep sea.”

*Gorchov Negron, A.,M., Kort, E. A., Conley, S. A., & Smith, M. L. (2020). Airborne assessment of methane emissions from offshore platforms in the U.S. Gulf of Mexico. Environmental Science & Technology, 54(8), 5112-5120.

Methane (CH4) emissions from oil and gas activities are large and poorly quantified, with onshore studies showing systematic inventory underestimates. We present aircraft measurements of CH4 emissions from offshore oil and gas platforms collected over the U.S. Gulf of Mexico in January 2018. Flights sampled individual facilities as well as regions of 5–70 facilities. We combine facility-level samples, production data, and inventory estimates to generate an aerial measurement-based inventory of CH4 emissions for the U.S. Gulf of Mexico. We compare our inventory and the Environmental Protection Agency Greenhouse Gas Inventory (GHGI) with regional airborne estimates. The new inventory and regional airborne estimates are consistent with the GHGI in deep water but appear higher for shallow water. For the full U.S. Gulf of Mexico our inventory estimates total emissions of 0.53 Tg CH4/yr [0.40–0.71 Tg CH4/yr, 95% CI] and corresponds to a loss rate of 2.9% [2.2–3.8%] of natural gas production. Our estimate is a factor of 2 higher than the GHGI updated with 2018 platform counts. We attribute this disagreement to incomplete platform counts and emission factors that both underestimate emissions for shallow water platforms and do not account for disproportionately high emissions from large shallow water facilities.”

*Meyer-Gutbrod, E., Kui, L., Nishimoto, M. M., Love, M. S., Schroeder, D. M., & Miller, R. J. (2019). Fish densities associated with structural elements of oil and gas platforms in southern California. Bulletin of Marine Science, 95(4), 639-656. [PDF] [Cited by]

There are thousands of offshore oil and gas platforms worldwide that will eventually become obsolete, and one popular decommissioning alternative is the “rigs to reefs” conversion that designates all or a portion of the underwater infrastructure as an artificial reef, thereby reducing the burden of infrastructure removal. The unique architecture of each platform may influence the size and structure of the associated fish assemblage if different structural elements form distinct habitats for fishes. Using scuba survey data from 11 southern California platforms from 1995 to 2000, we examined fish assemblages associated with structural elements of the structure, including the major horizontal crossbeams outside of the jacket, vertical jacket legs, and horizontal crossbeams that span the jacket interior. Patterns of habitat association were examined among three depth zones: shallow (<16.8 m), midwater (16.8–26 m), and deep (>26 m); and between two life stages: young- of-the-year and non-young-of-the-year. Fish densities tended to be greatest along horizontal beams spanning the jacket interior, relative to either horizontal or vertical beams along the jacket exterior, indicating that the position of the habitat within the overall structure is an important characteristic affecting fish habitat use. Fish densities were also higher in transects centered directly over a vertical or horizontal beam relative to transects that did not contain a structural element. These results contribute to the understanding of fish habitat use on existing artificial reefs, and can inform platform decommissioning decisions as well as the design of new offshore structures intended to increase fish production.”

*Nguyen, T.T., Cochrane, S.K.J., &  Landfald, B. (2018).  Perturbation of seafloor bacterial community structure by drilling waste discharge. Marine Pollution Bulletin, 129 (2), 615-622. [Cited by]

“Offshore drilling operations result in the generation of drill cuttings and localized smothering of the benthic habitats. This study explores bacterial community changes in the upper layers of the seafloor resulting from an exploratory drilling operation at 1400 m water depth on the Barents Sea continental slope. Significant restructurings of the sediment microbiota were restricted to the sampling sites notably affected by the drilling waste discharge, i.e. at 30 m and 50 m distances from the drilling location, and to the upper 2 cm of the seafloor. Three bacterial groups, the orders Clostridiales and Desulfuromonadales and the class Mollicutes, were almost exclusively confined to the upper two centimeters at 30 m distance, thereby corroborating an observed increase in anaerobicity [living in the absence of oxygen] inflicted by the drilling waste deposition. The potential of these phylogenetic groups as microbial bioindicators of the spatial extent and persistence of drilling waste discharge should be further explored.”

*Nyman, E. (2017). Maritime energy and security: Synergistic maximization or necessary tradeoffs?  Energy Policy, 106, 310-314.  [Cited by]

Offshore energy is big business. The traditional source of maritime energy, offshore petroleum and gas, has been on the rise since a reliable method of extraction was discovered in the mid-20th century. Lately, it has been joined by offshore wind and tidal power as alternative “green” sources of maritime energy. Yet all of this has implications for maritime environmental regimes as well, as maritime energy extraction/generation can have a negative effect on the ocean environment. This paper considers two major questions surrounding maritime energy and environmental concerns. First, how and why do these two concerns, maritime energy and environmental protection, play against each other? Second, how can states both secure their energy and environmental securities in the maritime domain? Maximizing maritime energy output necessitates some environmental costs and vice versa, but these costs vary with the type of offshore energy technology used and with the extent to which states are willing to expend effort to protect both environmental and energy security.”

*Punzo, E., Gomiero, A., Tassetti, A.N., Strafella, P., Santelli, A., et al. (2017). Environmental Impact of Offshore Gas Activities on the Benthic Environment: A Case Study. Environmental Management, 60 (2), 340-356.  [Cited by]

Multidisciplinary monitoring of the impact of offshore gas platforms on northern and central Adriatic marine ecosystems has been conducted since 1998. Beginning in 2006, 4–5 year investigations spanning the period before, during, and after rig installation have explored the effects of its construction and presence on macrozoobenthic communities, sediment, water quality, pollutant bioaccumulation, and fish assemblages. In this study, sediment samples collected at increasing distance from an offshore gas platform before, during and after its construction were subjected to chemical analysis and assessment of benthic communities. Ecological indices were calculated to evaluate the ecological status of the area. Ecotoxicological analysis of sediment was performed to establish whether pollutants are transferred to biota. The study applied a before–after control-impact design to assess the effects of rig construction and presence and provide reference data on the possible impacts of any further expansion of the gas extraction industry in the already heavily exploited Adriatic Sea. Only some of the metals investigated (barium, chromium, cadmium, and zinc) showed a different spatial and/or temporal distribution that may be platform-related. In the early phases, the sediment concentrations of polycyclic aromatic hydrocarbons were below the detection limit at all sites; they then became detectable, but without significant spatial differences. The present findings suggest that the environmental effects of offshore gas platforms may be difficult to quantify, interpret, and generalize, because they are influenced by numerous, often local, abiotic, and biotic variables in different and unpredictable ways.”

*Riddick, S.N., Mauzerall, D.L., Celia, M., Harris, N.R.P.; Allen, G., et al. (2019). Methane emissions from oil and gas platforms in the North Sea. Atmospheric Chemistry and Physics, 19 (15), 9787-9796. [PDF] [Cited by]

Since 1850 the concentration of atmospheric methane (CH4), a potent greenhouse gas, has more than doubled. Recent studies suggest that emission inventories may be missing sources and underestimating emissions. To investigate whether offshore oil and gas platforms leak CH4 during normal operation, we measured CH4 mole fractions around eight oil and gas production platforms in the North Sea which were neither flaring gas nor offloading oil. We use the measurements from summer 2017, along with meteorological data, in a Gaussian plume model to estimate CH4 emissions from each platform. We find CH4 mole fractions of between 11 and 370 ppb above background concentrations downwind of the platforms measured, corresponding to a median CH4 emission of 6.8 g CH4 s−1 for each platform, with a range of 2.9 to 22.3 g CH4 s−1. When matched to production records, during our measurements individual platforms lost between 0.04 % and 1.4 % of gas produced with a median loss of 0.23 %. When the measured platforms are considered collectively (i.e. the sum of platforms’ emission fluxes weighted by the sum of the platforms’ production), we estimate the CH4 loss to be 0.19 % of gas production. These estimates are substantially higher than the emissions most recently reported to the National Atmospheric Emission Inventory (NAEI) for total CH4 loss from United Kingdom platforms in the North Sea. The NAEI reports CH4 losses from the offshore oil and gas platforms we measured to be 0.13 % of gas production, with most of their emissions coming from gas flaring and offshore oil loading, neither of which was taking place at the time of our measurements. All oil and gas platforms we observed were found to leak CH4 during normal operation, and much of this leakage has not been included in UK emission inventories. Further research is required to accurately determine total CH4 leakage from all offshore oil and gas operations and to properly include the leakage in national and international emission inventories.”

For additional research about the environmental impacts of offshore drilling, please see the Science Primary Literature Database.

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