A survey vessel towing an airgun array during a seismic survey (Photo: International Association of Geophysical Contractors)
A survey vessel towing an airgun array during a seismic survey (Photo: International Association of Geophysical Contractors)

OPINION | The misplaced fury around sound: time to put the record straight on seismic surveys

Climate activists are making more than noise about 3D seismic studies being used to delineate oil and gas reserves offshore Africa. They've proceeded with legal action that may force Shell to pull the plug permanently on its search for hydrocarbons along South Africa's Wild Coast, the country's poorest province.

Seismic surveys use sound waves to help oil and gas companies build an image of hydrocarbon deposits buried deep underground. They are considered a fast and efficient way to map out new reserves, which is essential given that the world's oil and gas supplies are dwindling even as energy demand is soaring, and renewables aren't ready to do the heavy lifting of keeping the lights on around the globe.

At issue is Shell's plan to do a targeted seismic survey of a sub-seabed area in an exploration block the company acquired in 2014. Included in the acquisition were the former owner's permits to proceed with exploration activities, permits that were renewed in 2017 and 2021.

According to the new African Energy Chamber (AEC) report, "The State of South African Energy," in 2022 anti-fossil fuel campaigners, including Greenpeace, brought a case against the government's granting of exploration rights to Shell, including permission to perform seismic studies. The group argued that seismic surveys — or "blasting," as they characterise it — endanger the Wild Coast's marine environment. As evidence, they cited the beaching of a beaked whale and dead fish washing up ashore during the month-long seismic study Shell conducted before legal action shut it down. The group's lawyers contended that Shell's exploration activities "amounted to unjust administrative action" because the original approval process has since been updated and stronger environmental protections are now in place.

In December 2022, the High Court in Makhanda ruled it illegal for Shell to continue its surveys. The energy giant is awaiting the outcome of its appeal.

South Africa is a nation that needs much more domestic energy to end the crisis of rolling blackouts — never mind to expand economically and reduce its reliance on energy imports — but if the ruling stands, it could have a chilling effect on vital oil and gas development there (And it's not the only obstacle. See the report for a discussion of the challenges around exploration and production.). In the absence of an established renewables infrastructure, this decision is likely to plunge even more citizens into darkness. Right now, and for the foreseeable future, fossil fuels are what South Africa has to depend on to meet its growing energy needs. Why limit the chance to become energy secure when the solution lies just off the nation's shores?

The truth

But even if South Africa weren't facing an energy shortage, even if it had enough reliable electricity to keep homes, businesses, and other institutions humming, what's also concerning about the decision is that it pits science against conjecture.

It's time to tell the truth about seismic surveys.

The people who filed suit fear that energy exploration could "disrupt sea mammals' habitat and damage the ecologically diverse and sensitive environment of the Wild Coast." Scientists say they are concerned that the noise from the surveys will upset migratory patterns, stress the animals, and interfere with their ability to communicate with others and find food. They suggest that various marine species, including dolphins and sharks, "could be negatively affected by seismic surveys through behavioral changes to get away from the noise."

Reread those statements. People, and even scientists, say they "fear" or "are concerned" about the possible effects of seismic studies. They're worried about what could happen but haven't conducted any research to prove their points.

Energy companies, including Shell, have the same fears and concerns — no one wants to disturb whale pods or think their actions have starved dolphins to death — and have responded proactively. All told, they have poured millions of dollars into understanding how seismic surveys affect both the physical health and behavioural patterns of sea life.

For one thing, the global oil and gas industry has developed procedures for managing the impact of seismic activities — Shell timed its studies around whale migration patterns, deliberately mitigating the risk of disruption.  Seismic vessels use soft-start or ramping-up procedures as a matter of course. This involves activating small sections of the sound arrays over time, giving the marine animal a chance to swim away before the acoustic source moves to full strength.

In addition, research into how sound generated by exploration and production affects the marine environment is ongoing. For example, since it was established in 2006, the E&P Sound & Marine Life Joint Industry Programme (JIP), has spent more than US$31 million on research programs aimed at "providing better science, helping governments make regulatory decisions and industry develop effective mitigation strategies." That includes understanding how sound travels in the ocean as well as the physical and behavioral effects of sound exposure over the course of a marine mammal's life.

Monitoring and mitigation are also JIP priorities. The Marine Mammal Observer Association (MMOA) says that when passive acoustic monitoring (PAM) is used alongside visual observation, it greatly improves the possibility of marine mammal species being detected, especially during low visibility and nighttime conditions. And, as in so many things in life, early detection improves outcomes. JIP has developed PAMGuard, a software system for detecting the presence of marine mammals near seismic operations. The system, in use worldwide, allows operators to shut down seismic activity if the software or an observer indicates a marine animal has entered what is known as the exclusion zone once seismic operations have begun.

A bubble, not a bang

When green groups talk about seismic activity in the oceans, they use words like "explosions" and "gun blasts" — language intended to generate a visceral, negative response.

But energy companies aren't throwing bombs into the ocean when they do a seismic study, hoping for some unpredictable ripple effect that will point them in the direction of oil or gas. Seismic technology is highly refined, well understood, and has been proven over nearly 50 years to be a safe practice.

The compressed air sources used today do not produce ultrasonic shock waves. The fact is, modern seismic technology is more like the ultrasounds used for imaging the human body than it is to anything more percussive. The impulses produced during a seismic study by an array of compressed air sources are nothing like an explosion. Instead, they are more accurately described as a "collapsing air bubble that emits a low-frequency sound that travels through the earth's crust," meaning they are comparable to many naturally occurring ocean sound sources. Most of all, the sounds are temporary, transitory, and they generally occur at frequencies below the hearing range of many marine species. It's important to note that no one conducts a seismic survey without performing environmental impact studies first; these are often done in addition to host countries' requirements to identify marine species and other environmental sensitivities.

Incidentally, the oil and gas industry isn't the only one to conduct seismic surveys. Even the renewables sector uses them to select sites for offshore wind, tidal, and wave energy installations, although those studies have not been meant with any resistance. Seismic studies are also used for harbour and ship channel engineering, tsunami preparedness, siting of buried cables, and even to support economic zone claims. The fact that the effort to shut down Shell's plans is because they involve fossil fuels has never been more transparent.

Continuous improvement

So, the million-dollar question is this: Do seismic studies cause the kind of harm activists say (or perhaps even hope) they do?

The answer is a resounding no.

None of the considerable research into the impact of seismic surveys on marine life, including fish and marine mammals, has indicated any direct physical injury or biologically significant negative impacts, although they have found temporary behavioural changes as far as a few kilometres out. That's after more than 300 seismic studies have been completed around the world. During the legal proceedings involving Shell, the company said that during the last decade there had been 35 seismic surveys conducted offshore South Africa, each one of them lasting about three months.

Energy companies aren't resting on their laurels, however. The industry is actively working to further minimise any possibility that their search for oil and gas can harm ocean life. As former navy research scientist and compliance officer Robert Gisiner, now the International Association of Geophysical Contractors (IAGC) director of marine environmental science and biology, points out, oil and gas exploration and production companies are looking at what he called "novel sources" to replace current compressed air technology. And advances in computer technology have improved the already outstanding safety record of seismic surveys. Gisiner wrote in Acoustics Today, those improvements have encouraged "the collection of larger 3-D data sets that cover more area with less acoustic output."

As the AEC has said before, South Africa needs energy. That's the bottom line. Africa deserves the opportunity to capitalise on its own oil and gas resources, and we must be able to exploit these resources in order to benefit from our continent's full potential.

The arguments from the climate activists who put Shell's seismic plans on pause may be full of sound and fury, but the science suggests they signify nothing.

This opinion piece is reposted here with the permission of the African Energy Chamber.

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