Seismic scare tactics

GREEN groups are crying “earthquake” in their latest campaign to scare communities into opposing Australia’s emerging shale gas industry.
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Multi-stage fraccing, courtesy BHP Billiton Petroleum.

Staff Reporter

The claim that fraccing causes earthquakes has already been used by opponents of the coal seam gas industry in the eastern states, although it was secondary to other issues about aquifers, management of wastewater and land access.

The shale gas industry is not such an easy target.

It operates kilometres below local aquifers and shale gas is typically in gas-saturated rocks. There is no water management except for the liquids pumped in to frac the rocks.

Australia’s most advanced shale gas plays also have the advantage of being in the remote Cooper Basin, with few competing land users.

Unlike New South Wales’ CSG industry, the Cooper Basin is certainly not encumbered by Macquarie Street farmers and their powerful friends in the media.

Against this background, opponents of shale gas have few weapons left in their arsenal but are realising the earthquake message has plenty of scare potential.

The green groups were helped recently by an Oklahoma University study that generated headlines about a supposed link between fraccing and earthquake activity.

In fact, the report found increased seismic activity linked to disposal of water from conventional oil production wells.

Somehow, that became a “cautionary message” about what might happen in the US shale gas industry.

The logarithmic nature of seismicity makes it great material for misinformation and media headlines.

For example, the Richter scale is a base-10 logarithmic scale. A magnitude 4 earthquake has 10 times the measured amplitude on a seismograph of a magnitude 3 earthquake and releases more than 30 times the amount of energy.

The scale means a magnitude 3 quake, which most people could not even feel, releases about one-thousandth the amount of energy of magnitude 5 quake.

However, the average newspaper reader sees the numbers 3 and 5 are not far apart, so the earthquake must be comparable.

It is a weakness in nomenclature that can be exploited by opponents of the shale gas industry, as is the fact that “earthquake” can even be used to describe small seismic events.

Exponential scales also govern the frequency of earthquakes.

There are millions of earthquakes every year in the range 2 to 2.9 and this is only the ones that are measured.

If more seismographs are installed to monitor activity, the more earthquakes there seem to be.

Beach Energy managing director Reg Nelson is a leader of shale gas development in Australia and a former earthquake seismologist.

He has a unique perspective and has seen it all before in opposition to the original development of the Olympic Dam copper-uranium-gold mine.

“Back in the 1980s there was strong opposition and the usual forces started to campaign against the mine,” Nelson said.

“I was then chief geophysicist for the Department of Mines and Energy and had recently taken over the State Earthquake Seismology Network and made substantial upgrades to the extent and quality of the network, to the extent that we had a much wider geographical detection coverage and instruments with much greater sensitivity.

“The nature of earthquakes is that they are always with us in a dynamic and tectonically active Earth – and their magnitude and frequencies tend to follow power laws [when plotted on a logarithmic graph their distribution is linear] – that is, there are many more smaller earthquakes as the magnitude drops off.

“I received a phone call one day from someone [who turned out to be a from a group opposing the Olympic Dam mine] who pointed out – quite accurately – that the number of measured earthquakes along the G2 corridor [a major lineament in South Australia associated with earthquakes and having some correlation with mineral deposits such as at Olympic Dam] had increased significantly over a year.

“I agreed.

“The interlocutor then sought to get me to say that it was because of the Olympic Dam mine.

“I was happy to remain scientific and objective in my response, which was that if we had been recording with the old instrumentation we would have seen no statistical variation of significance.

“The difference in my view was undoubtedly because we were measuring a much larger number of low magnitude earthquakes that hitherto were not able to be recorded.”

Nelson said these were the sorts of questions that needed to be asked in any debate about increased frequency of earthquakes in relation to fracture stimulation.

“Initiation of fractures when stimulating rock formations hydraulically is bound to produce microseisms – in the same context that jumping up and down produces microseisms,” he said.

“It is more a question of the magnitude. Swarms of natural earthquakes are around us every day but we rarely, if ever, feel them.

“The whole point is that I can stamp my foot on the ground and produce a seismic event – but will it do you any harm?”

A Durham University study released this week echoes Nelson’s views. The study found fraccing did cause seismic events but these were almost always undetectable.

The largest fraccing-related seismic event ever felt was a 3.8 magnitude earthquake in Canada, which is much smaller than earthquake activity created in the past by mining and building large dams.

Green groups will keep pushing the message about earthquake risk, although they have their own weak spot.

Fraccing is an essential process in liberating geothermal energy, which is a darling of the renewable energy lobby.

The use of fraccing in geothermal cannot be disputed.

Nelson points out that when it finished the frac job on the Holdfast-1 shale gas well in the Cooper Basin, the frac equipment and crew moved to the Paralana-2 geothermal well between Lake Frome and the northern Flinders Ranges (a joint venture between Petratherm, Beach and TruEnergy).

The French government has come up with an unusual solution to this dilemma.

France banned fraccing in 2011 but that has not stopped it awarding geothermal exploration licences.

The proponents of geothermal energy projects and the environment minister argue they are not fraccing but stimulating existing fissures in the rock.

The projects ''won't use fraccing in the strict sense of the term because there won't be fracturing,'' Bureau de Recherches Geologiques et Minieres geothermal division head Romain Vernier said.

''Hydraulic stimulation at the onset will reopen existing fissures blocked by mineral deposits and then it won't have to be repeated.''

Good luck with that argument in Australia.