Creating the right environment

Andrew McBarnet says it makes sense for the oil and gas E&P business to provide more independently researched evidence documenting best environmental practice in its operations. 

A recent fragment in the oil industry news cycle noted that electromagnetic (EM) offshore surveys do not have the potential to have a significant effect on any of the important animal groups in the oceans such as fish, seabirds, sea turtles, and marine mammals. In addition, cumulative effects from EM surveys are negligible compared to natural EM anomalies, induced fields from natural water currents, and other anthropogenic EM sources such as those originating from undersea equipment especially power lines and associated electrodes.

One obvious question is whether anyone actually needed this report, Environmental Impact Assessment of Electromagnetic Techniques Used for Oil & Gas Exploration & Production, which runs to an impressive 166 pages with a plethora of references (over 400 reports and publications were reviewed). The findings are obviously reassuring to an embattled oil and gas E&P business which, in the wake of Macondo, has spent the last year or more defending itself against accusations of being environmentally irresponsible. Here at least is some good news.

Offshore EM operations (courtesy of EMGS).

The report emanates from an independent environmental impact assessment prepared by LGL, a Canadian environmental research consultancy, for the International Association of Geophysical Contractors (IAGC), which provides a clue as to how the study arose. Basically EM operations have been going on for over 10 years without any awkward environmental questions being asked, so to speak. To its credit, an IAGC subcommittee some time ago recognized that in a climate of suspicion about all E&P marine operations, someone would come knocking at the door at some point and question whether offshore EM is actually safe.

Environmental protection organizations have been very successful in persuading governments worldwide to investigate – and mitigate with regulations – the potentially harmful effects of offshore survey noise from airguns used during seismic acquisition surveys on marine life and in particular marine mammals. Numerous studies have been initiated in active E&P offshore provinces, notably in Norway, UK, Australia and of course the US. There has yet to be a definitive study, and there probably never will be, which shows that seismic surveys have had a significantly harmful effect on marine mammals. The evidence to date indicates that airguns probably do interrupt the underwater communication systems of some mammals, but any disturbance has not been shown to cause serious changes of behaviour or be life threatening.

When it comes to fish, the most thorough research has come out of Norway where the fishery business plays an important role in the country's economic and community life. A crude summary would be that only those fish that get in the way of the compressed air bubble shot by the airgun to the seabed suffer physical harm – and that is a negligible number. In any case the normal reaction of adult fish would be to swim away from the sound. Marine biologists do say that fish eggs and larvae within a few metres of the airgun noise/ pressure may be affected by the seismic shooting, but the mortality rate per day is said to be miniscule.

This is not of course what you read in partisan texts by environmental groups, a constant source of aggravation for the IAGC when representing the interests of its members to government regulatory authorities. It is probably not well enough understood that the marine seismic industry worldwide already complies with numerous regulations governing survey operations designed to protect mammals and fish and has its own code of practice. However, we live in a soundbite world in which the oil industry is an easy target, more so since Macondo, so that governments cannot afford to ignore the often emotional rhetoric from environmental protection groups even when their claims are taken out of context or are simply unsubstantiated.

Evidence based
Underwater life at risk. EM offshore operation being carried out by Norwegian company EMGS.

IAGC has sought to base the conversation on scientific evidence as the only way of persuade a sceptical world that marine seismic operations are environmentally responsible. This is actually a doubleedged sword because on the one hand it focuses on the need for good, citable research, but on the other it provides governments the opportunity to prevaricate by commissioning yet more studies.

The issue has probably been most acute in the US jurisdiction over the Gulf of Mexico, where the Bureau of Ocean Energy Management (BOEM) has still not clarified its updated marine environment protection regulations for marine seismic operations. More restrictions on survey activity are anticipated, it's merely a question of how stringent these may be. With the protection of mammals' peace and quiet in mind, changes may impact the number of surveys in any given area, survey hours of operation, mammal observation requirements, etc. Any alterations to current practice are likely to have cost implications. Amid the uncertainly which reigns BOEM has at least allowed one or two wide-azimuth survey proposals from the main contractors to go ahead. The other positive is that OCS lease sale 218 for the western Gulf of Mexico has been scheduled for 14 December, a long delayed auction. Once completed, it is bound to stimulate seismic exploration plans from oil companies anxious to make up for lost time, ie it will be make up your mind time for BOEM regarding new regulations for seismic.

BOEM is currently sitting on one scientific report, Seismic Survey Mitigation Measures and Marine Mammal Observer Reports, which was initiated in 2002 as a result of the 2002 National Marine Fisheries Service (NMFS) Biological Opinion for Lease Sale 184 (western planning area). The purpose of the study is to summarize and synthesize seismic survey observer reports submitted for the years 2002-08. Recommendations are awaited as to the effectiveness of required mitigation measures, as well as suggestions for new and/or improved mitigations. Seismic operators in the Gulf of Mexico have been required to submit reports on the 1st and 15th of each month to include an observer effort report, survey reports and sightings report. As part of the original Biological Opinion that resulted in the seismic survey observer programme, NMFS also required that an annual report be submitted documenting all sightings of sperm whales and sea turtles, the species likely to be sighted that are currently listed under the Endangered Species Act (ESA). As a result, BOEM says it now has considerable data from the observer programme and is in a position to evaluate existing mitigations and their effectiveness. These data are considered timely for both BOEM and NMFS as the US Marine Mammal Protection Act (MMPA) goes through the rulemaking process.

The very deliberate approach towards mitigating the possible environmental risks in marine seismic operations has been the hallmark of policy-making not just in the US but in many countries with significant offshore oil and gas activity. A lot of other countries simply copy the regulatory requirements put in place by the US, Norway, UK etc.

This is why it was smart of IAGC to take pre-emptive action with regard to the status of offshore EM in terms of potential environmental hazard, and make it a positive story in the process. The LGL report should act as a deterrent to any frivolous claims that EM operations put marine life at risk. IAGC's willingness to sponsor an independent EIA may also possibly persuade governments that no measures of their own are needed. Marine EM surveys use a towed electrical source accompanied by bottom-mounted or towed receivers which have typically been towed near the sea bottom in water depths of 500m or more. LGL considered equipment, materials and activities characteristic of EM surveys which had at least some potential to affect key members of the marine ecosystem. It cites underwater noise emissions (from thrusters during extensive maneuvering when bottom-mounted antennae are deployed and retrieved), light emissions, accidental events such as ship strikes, and small oil spills and EM emissions (electromagnetic, the primary focus of the EIA, and electrolysis at electrodes).

The report provides some admirable detail about all the factors which could impact marine life and, in a sense, illustrates how all marine industrial activity is vulnerable to scrutiny given the many possibilities for environmental impact. Fish, seabirds and sea turtles are all capable of detecting underwater sound and may react to those sounds. In general, these groups are not considered to be nearly as sensitive as marine mammals, especially cetaceans. Controlled source electromagnetic (CSEM) survey vessels may use thrusters extensively and intermittently when retrieving bottom-mounted receivers, which could number as many as 200 or so. The underwater noise generated by thrusters is acknowledged as a source of minor disturbance to marine mammals, perhaps more so than the steady noise of ship propulsion when moving at a constant slow speed. The report admits that there is no mitigation except to select quieter models of thruster if available and to minimize the use of thrusters where feasible.

Light emissions from any work platform at sea have the potential to attract prey that in turn may attract predators such as fish, sea turtles, seabirds and marine mammals. In the case of an EM survey vessel with work lights illuminating the decks, such attractions can be considered localised and transitory, and any effects are probably negligible. In all the seriousness that a report of this nature requires, it states that light emissions can attract birds at night and in some cases (eg on nights with poor visibility) birds may collide with the superstructure and become stranded ‘and/or suffer mortality'. Apparently in the northwest Atlantic, these kamikaze events are a relatively common occurrence at certain times of the year.

The small oil spills and light emissions could affect marine birds although most effects can be mitigated and all would be small scale (although arguably not the case for an endangered species), according to the report. Meantime accidents such as ship strikes of sea turtles and marine mammals are unlikely given the slow speeds used during EM surveys and the abilities of most large animals to avoid the vessel and towed equipment.

Unique aspects

The crux of the report is the consideration of the unique aspects of EM surveys, in other words the electromagnetic emissions from a towed electrical source. The source may be towed near surface or near bottom in shallow or deepwater. The report notes that electromagnetic energy obeys the diffusion equation. This means that the signal strength falls off proportionally to r2 (where r is the distance from the source). Seismic energy, on the other hand, obeys the wave equation where the signal strength falls off proportionally to r. The result is that EM energy attenuates far more rapidly than seismic energy and thus its effect is much more localised. Given the localised EM source zone of influence the duration of any effects will be shorter.

The source emissions (single or multiple frequencies) have virtually no potential for causing health effects because they are very low frequency and exposure times are of short duration. However, the report states that some marine animals such as elasmobranchs – hands up those who know these are sharks, skates, and rays! – have highly developed electro-receptive organs and most likely can detect EM emissions. Some animals may use naturally occurring electromagnetic information to navigate (eg young sea turtles) and others may use the information to detect less visible prey at close range. This leads the report to conclude that elasmobranchs may be the most sensitive group to EM emissions since they have been shown to use them to detect prey at close range particularly in areas of low visibility.

Based upon attenuation data provided by the EM industry, studies of the reactions of various animal groups to electric and magnetic fields, and some simple calculations by the report's authors, it is concluded that the ‘zone of influence' of a typical source would be less than 400m radius in most cases. In addition, the time of exposure would be in the order of minutes between a moving source and a mobile animal.

Some animals may use electric or magnetic fields for navigational purposes. However, it is thought highly likely that these fields would represent only one cue among a suite of navigational cues such as sun angle, olfactory, current strength and possibly others. A total dependence upon geomagnetic cues would most probably render the system useless during moments such as solar storms or locations of anomalies. The report adds that Earth's electric field is DC whereas most EM surveys emit AC fields. It says that several companies provided attenuation data for their specific gear that were calculated using a standard set of parameters. These data were then compared to sensitivity data derived from published literature on elasmobranchs. Thresholds of effects (primarily behavioural) suggest that any effects would only occur within radii of 400m or less in most cases and only for a matter of minutes under any realistic scenario.

The LGL report and its conclusive dismissal of any environmental fears regarding offshore EM operations may go unnoticed by many, but it will be something that geophysical contractors offering offshore EM surveys can wave in front of oil companies and government regulators as reassurance and evidence of pragmatic concern.

Indeed it could usefully serve as a template for further authoritative reports on other aspects of E&P operations, not just geophysical activities, which can challenge the public perception of oil companies and their contractors placing profit above concern for safety and the environment. OE

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