ReFinE: Putting Things into Context
In his speech at the Unconventional Gas Aberdeen 2014 conference, Richard Davies, Head of Energy, Durham University, introduced the institution's Research Fracking in Europe (“ReFinE”) initiative, which aims to separate the facts from fiction when it comes to shale gas.
He recalled the “known unknowns,” a phrase made popular by former US Secretary of Defense Donald Rumsfeld. Of unconventional gas, Mr. Davies reported: “There are a lot of 'known knowns' – there have been hundreds of thousands of fracking operations - fracking technology in some guise has been around for many decades.”
Regarding a study of fracture heights, he asked conference participants if they'd seen such a graph showing how far below the aquifer hydraulic fracturing occurred. Mr. Davies remarked, “Look, there's a scale bar here – thousands of feet, down to 8,000 feet. It's critically important we include scale bars on all diagrams related to fracking, so that we can show where the water supplies are – here – and where the fractures are - down here.”
He added that the tallest fractures on the diagram were up to 600 meters high. “Those are the very exceptional ones; most of them are just a few hundred meters and even less than that. And you can see there are thousands of feet separating the water supplies from the fracking operations.”
At Durham University, he explained, such data had been converted into probability plots, showing the probability of fracturing exceeding specific heights. He stated that the chance of a fracture going beyond 350 meters, based on five different data sets from the US, is 1%.
“The chances of fractures getting 4-5-600 meters get very small indeed,” he said, addressing the key question of whether or not fracking could cause water contamination. “This provided a pretty good evidence base that followed up on Pinnacle's research to say 'this is very unlikely indeed,' simply because fractures aren't tall enough to go from 3 kilometers to the surface, where the water supplies are located.”
Another issue his organization had addressed was seismicity – another issue of concern to the public, particularly because of the “Lancashire event” in 2011.
“What we did here was to try and put induced earthquakes into context,” explained Mr. Davies. “What's their history, how many have we created, what industrial processes created them? What magnitudes were recorded? And how does fracking fit in to that – is it important compared to all of the other processes that can induce seismicity?” he asked.
The vast majority of the energy from fracking, he explained, was below 0.5 in magnitude – most of it below zero. “So it can't be felt,” he explained, “but it can be monitored and measured using microseismic techniques.”
Occasionally, he admitted, there was a felt earthquake, which ReFinE was keen to look at published a paper on in 2013. Showing a graph of the history of induced seismicity since 1929, created by a wide array of activities: salt solution mining, waste disposal, geothermal, conventional oil and gas depletion, etc.
He explained, “Fracking has created three examples of felt seismicity since fracking has been carried out, so after hundreds of thousands of fracking operations there are three examples. Ironically, oil and gas field depletion is creating bigger induced earthquakes; even very clean technology such as geothermal has a history here.”
The other processes, he said, created bigger events than fracking did.
“It doesn't mean we should be complacent about it, but it puts it in context.”
Most recently, his research group had published a paper on well integrity, reviewing the number of wells that had been drilled around the world onshore, taking all published, reliable data sets on well barrier and well integrity failure into account (25 different data sets). He showed examples from Pennsylvania, where up to 6% of wells had shown some sort of internal or external leak.
Of the conclusions he cited 2,152 wells in the UK that had been drilled since 1902. “We estimated that between 50 and 100 are orphaned; this is a small issue compared to orphaned wells in the US, where in some states there are tens of thousands of orphaned wells because they have a long history of drilling.”
Access to such data was essential for the public, he said, to enable them to assess whether such phenomenon were an issue or not in the UK. Mr. Davies commented, “Intuitively, it probably isn't an issue in the UK simply because we haven't had people ringing up in the 1950s, 60s and 70s saying they had a leaking well in their back garden, but I'm afraid that's not good enough – there needs to be more information to reassure people about activity going forwards.”
“Black swan” events were the reason to proceed with caution going forward, he explained: “People assumed for hundreds of years that black swans never existed; they were all white until someone found one and realized that it couldn't be predicted.
“So these are the events we need to be very cognizant of,” he said. “What could happen? What's the worst-case scenario – the one in a thousand, one in 10,000 event is the one that we need to be aware of.”
Those were the kinds of things ReFinE was looking into, things that could be considered “live” questions, for academics and members of the public, among others. One example was “how far from a fault is it safe to be carrying out hydraulic fracturing operation – a reasonably sized, critically stressed fault?” Mr. Davies asked if there was a rule of thumb for this.
He noted that there was a lot of natural seismicity taking place in the UK and a number of stations monitoring it. “But do we know which faults are moving? Which are critically stressed. Actually, this data could be repositioned so that we can actually find out which fault has been moving – if it can be positioned properly in three dimensions, it may be possible to work out which fault exactly is critically stressed, is thinking about moving and needs to be avoided.”
Only a fraction of the energy used in fracking was actually recorded, according to Mr. Davies.
He reported he was also working with engineers at Durham University on predicting where fractures went. “Rocks are heterogeneous, they're variable, and so the exact location of fractures that form is a very difficult thing to predict.”
Members of the public were also asking if fluids could move up faults, or how far the fluids might go. “Are fluids going beyond the maximum extent of the fracture? We don't think that's occurring, don't think it's a problem, but do we know – do we have enough confidence there?”
Finally, Mr. Davies showed a simplified diagram of a drilling and fracking operation – which had no scale measurement to show how far away fracking was from the aquifer - and said it was crucial that the industry improve in its communication of such matters.
“We need to give perspective, we need to give context. We need to build trust. We need to be open about the risks – there's no such thing as an energy technology that's 100% safe.”
ReFinE groups a number of different organizations, like the National Environment Research Council, several oil companies, a number of research partners, and had advisor stakeholders, like the Environment Agency or Joint Research Centre in the European Commission and the Department of Environment and Climate Change. It also supporting organizations like the Royal Society of Chemistry and the Bulgarian Geological Society.
“It takes this entire group to move this project forward, and each member of the group has a different role in making sure that the research is carried out independently and on time,” said Richard Davies.