My first media hack job: "The Truth Behind the Dash for Gas"

The Truth Behind "The Truth Behind the Dash for Gas"

Talk to media people enough, and something like this was inevitable, but it seems that I am the star in a new anti-fracking documentary entitled "The truth behind the dash for gas" (my part starts from about 20 minutes in).

Back in November last year I received an email from a young guy who said he was looking to make his way as a film-maker just out from film-school. His email to me is quoted below:

I am putting together a short film about fracking in Somerset. The aim is to present a fair and informative assessment of the potential for fracking in Somerset, the risks and dangers associated with it, and the views of local people. The film and those working on it are independent of both the anti-fracking campaign groups and those who stand to gain from the fracking industry.

I think just by watching the first few minutes of the film you can see that their  claimed intent "to present a fair and informative assessment of the potential for fracking in Somerset" is barefaced lie. Even more barefaced is their claim that "the film and those working on it are independent of [...] the anti-fracking campaign groups". However, the film has a facebook page, in which it clearly states that the film is facilitated by Frack Free Somerset. The FrackFreeSomerset and FrackOff websites appear prominently in the credits at the end of the film.

Given that the very first contact between myself and the film makers was a lie, one can hardly expect the remainder of the film to do any better. I find it especially ironic that the 2nd word in the film title is "truth", while their very first contact with me was an obvious, barefaced and outright lie. It's not worth my time to address the content of the film as a whole, but I do want to comment on the parts in which my comments have been used.

Comment #1: that debate over hydraulic fracturing has descended into a media slanging match, and I don't think anyone could disagree with that. However, the film moves straight to the same science denialism more usually seen in the anti-climate-change world - if you can't trust the Royal Society for advice on scientific matters, the British Geological Survey, or the Geological Society, for matters geological, or Public Health England for public health matters, then I'm not sure where is left for you to turn, and the term conspiracy theorist begins to apply (see my final comment for more in this vein).  

As for my own 'close ties', I spent 3 months in the BP Institute in Cambridge as a 20-year-old M.Sci student. While BP provided the funds to set up the lab, the students who do projects there are  university students, and have no connection to BP (I certainly spoke to noone from BP while I was there, and in fact the majority of research being done when I was there was on developing energy efficient buildings). I also spent a few months in Rijswijk in Shell's research facility during my Ph.D. During my Ph.D I developed geophysical techniques to ensure safe storage of CO2 in geological reservoirs - so-called CCS, a potential method to mitigate climate change. During this time Shell asked my to come over and help apply some of these methods to their test site at Ketzin, Germany. All of this is made abundantly clear on my website.

Comment #2: I say that in many cases the impacts have been exaggerated. The Scranton Times-Tribune investigated claims made by residents about shale developments in Pennsylvania, finding that 77% of accusations were without substantiation. Surely an example of impacts exaggerated? Equally, even in cases where regulatory breaches by companies have lead to issues - the example of Dimock springs to mind - the impacts of this have been regularly exaggerated. At Dimock, while methane was found to have contaminated groundwater, there was no evidence of fracking fluids in the water. It's not good to have methane in groundwater, and this should be prevented from occurring at all times. However, methane is not toxic or harmful to human health, barring the risk of explosion if it allowed to accumulate in significant amounts. After the company had been cited and forced to repair its wells, levels of methane dropped, returning below the minimum safety levels set by the EPA (a fact never mentioned by activists, who will tell you that once contaminated, an aquifer can never be restored).

Comment #3: The most famous flaming tap in Gasland, the Markham well, had nothing to do with oil and gas drilling. This has been made abundantly clear by the Colorado State regulator (COGCC), which felt the need to release a comment to "correct several errors" in the film. The flaming tap is the headline image of Gasland, it appears in all the trailers and promotional material. That the gas is of biogenic origin, from shallow layers well above those targeted for drilling, implying that gas drilling is not the cause. This film attempts to argue that poor well casing still allowed shallow biogenic methane to migrate. However, the COGCC report makes clear that "there is little or no temporal relationship" between gas drilling in the area and the complaints made about the Markham and McClure wells. This is a fairly massive oversight to be made, one that I think that is worthy of comment. Clearly the film-makers find it easy to relate to other films that are economical with the truth in order to tell a story.

The regulators did rule that a drilling company was at fault in the case of the Ellsworth well. This company reached a settlement with the claimant (again, a fact that the film neglects to mention). The COGCC conducted sampling over a 170 sq mile area, and the Ellsworth well was the only one where any impact was detected. Strangely, we don't get to see Josh Fox setting the Ellsworth taps on fire - one can only guess at why?

The next sleight of hand is either quite clever, or monumentally dumb, I'm really not sure which. They move on to discuss the Duke methane studies, which I have discussed in previous posts here and here. Of course, there are a number of studies performed along along these lines, all of which come to very different conclusions to the Duke study. For some reason the film makers don't mention these (one wonders why). However, these film-makers can't even get the Duke PNAS study facts right! A screen-grab of the PNAS abstract is shown, highlighting an apparent claim that methane was found in 82% of drinking water within 1km of a gas well.

 How about we look at that section of the abstract in full:

In fact, you can clearly see that the 82% figure refers to all the water sampled, not just the ones near gas drilling sites. Methane was found in 82% of water samples, REGARDLESS OF WHETHER THEY ARE NEAR GAS WELLS OR NOT! Incidentally, this is a similar percentage to that found by Molofsky et al., who sampled a much larger dataset (1,700 samples vs 140 samples), finding that 78% of samples contained methane, regardless of proximity of gas wells. In fact this is why establishing whether shale development has caused problems is so difficult in Pennsylvania - there is already a lot of methane in the groundwater. Where studies have been conducted in areas where natural methane is not present in shallow water, they have not seen an impact from drilling.

I honestly find it hard to believe that this accidental highlighting of parts of two sentences, conveniently removing the context to make a scarier quote, is accidental. Either way it is particularly dumb to hope that people familiar with the source material won't spot the attempted trick.

Comment #4 is about well integrity. The astute among you will notice a cut in the editing between the start and end of my answer. Clearly, other things I've said have been edited out. Sadly, this interview was conducted a year ago, so I can't remember exactly what I said, and back then I was too naive to make my own recordings (not a mistake I'll make again), but presumably it was something that didn't fit with the narrative being portrayed.

The films then cuts to the SLB Oilfield Review from 2003. Always a good litmus test of a shale gas commentator is how they treat this report. Firstly this report covers data from deep offshore in the Gulf of Mexico. This is a very challenging drilling environment, so it's not surprising to have more problems offshore than onshore. The only statistics relevant to onshore UK shale drilling are stats from other onshore wells.

More importantly, the film describes the stats as showing either "leakage" or "failure". In fact, they depict incidents of Sustained Casing Pressure. SCP isn't a good thing, and again it should be avoided, but it doesn't equate to the mass leakage of hydrocarbons into shallow layers. Categorically, these stats have no bearing on the rate at which well integrity issues are causing contamination, which is what, misleadingly, the film tries to claim.

The most obvious place to look for wellbore integrity-related contamination issues from onshore wells drilled under a UK regulatory system, is of course to look onshore in the UK, where we have drilled 2,000 wells already, many of them in the 1960s, 1970s and 1980s (making most of them 30 years old at least). One of the few things this film gets right is that whether a well is fracked or not has no bearing on wellbore integrity issues. Therefore, if the statistical claims made in this film were true, there would be 1,000 onshore contamination incidents already. If the bold claim that follows ("all wells leak eventually") were true, we'd surely have 2,000 incidents by now. Clearly the claims made in the film do not add up, because I'm not aware of any problems associated with onshore wells in the UK.

Similarly, after the Piper Alpha disaster, regulations were significantly tightened to prevent such an event ever happening again. Again, the North Sea has not been turned into an environmental wasteland - we're still so keen to eat North Sea cod that there's almost none left!

We can also look to the US, which has hundreds of thousands of onshore wells, and actually examine statistics relating to actual incidents of groundwater contamination, as opposed to SCP. Luckily, the US Groundwater Protection Council has done exactly this, in a study released in 2011. They find that of 187,000 wells drilled in Texas, and 33,000 wells drilled in Ohio, only 21 and 12 wells respectively had seen casing issues leading to contamination, rates of 0.01% and 0.04%.

Comment #5 regards regulatory differences between US and UK, and resulting differences in operating practices. The above statistics show that contamination is not endemic to shale drilling. However, even the handful of cases that have occurred is a handful too many. These few incidences are inevitably the result of poor practice, and/or the contravention of regulations.

While I'm speaking, they cut to some shots of flowback waste pits. What they fail to point out is that these are not allowed in the UK - any waste flowing back from the wells must be stored in double-lined steel tanks. This is with good reason: in the GWPC report I mention above, the majority of drilling-related contamination incidents (172 in Ohio, 190 in Texas) have come from surface activities, not from processes happening under the ground. In the US it is common to store the waste fluid in open, plastic-lined pits. These have been known to overflow during heavy rain, or for the liners to tear, allowing the contents to leak. I think the endless shots of waste-fluid pits that activists like to show indicates either that they are not aware that these are banned in the UK, or that they do know this but don't like to let facts get in the way of the story.

For example, in one well-publicised case XTO opened the valve on one of their tanks, allowing the fluid to flow out into the ground, while in another case a trucker dumped his load into a nearby storm drain, rather than taking it to the treatment plant. This sort of illegal activity should absolutely be prevented, and it is important that regulators keep a sharp eye on operators to ensure that this doesn't happen. But it doesn't show that shale gas development is inherently problematic. Again, we can look the the UK example for dealing with produced water. The existing UK onshore industry handles 70 millions barrels of produced water a year, with no apparent contamination problems.

The next interviewee, Laurence Rankin, is presented a "Former Environment Agency manager", with the obvious intention of making us think that he is an impartial commentator. Since my 3 months as a 20-year-old M.Sci student at the BP Institute is worthy of mention, maybe the film should have also pointed out that he is also a coordinator of the Sefton Green Party and member of Friends of the Earth, so perhaps slightly less impartial than first appearances might suggest. While the Green Party man seems to have a problem with Cuadrilla's activities, the Environment Agency itself doesn't, and hasn't claimed that Cuadrilla have broken any of their regulations. The fact that the Green Party man isn't familiar with fracking, doesn't mean it hasn't happened. For example, horizontal wells have been fracked at Wytch Farm in Dorset. Update - this comment reflected media reports regarding Wytch Farm. Water is injected into the Wytch Farm reservoir, but this is to increase the reservoir pressure and drive oil towards production wells (a common practice in conventional fields), not to fracture the rock.

The use of the term 'slick-water' is another slight of hand, somehow implying that slick-water is somehow worse that what has gone before. In fact, in the good old days it was common to use a mix of gelled gasoline and napalm as the frack fluid. Given the choice of water with 1% chemical additives, or gasoline and napalm as the frack fluid, the use of slick-water represents an improvement. And the fact that there were no specific references to fracking in exploration licenses is that it was considered such a normal part of oilfield and drilling activities (with 10% of existing onshore wells being hydraulically stimulated). The main difference between now and what has gone before is one of scale, with modern treatments using higher volumes, rather than any major differences in the technique itself.

The film moves on to the Cuadrilla-induced earthquake near Blackpool. The next mistake made comes with the claim that the increase in earthquakes seen in US is directly attributable to hydraulic stimulation. In fact, the increase in seismicity is caused by an increase in the volumes of waste fluids, from both conventional and unconventional operations, being disposed of by deep injection into saline aquifers. I know this because I have worked in depth on these events, including writing a report for parliament, because they have implications for CCS. There are no proposals in the UK to dispose of fracking fluids through injection into deep aquifers. As far as I am aware, we do not have suitable deep saline aquifers onshore (although we are targeting such aquifers offshore in the North Sea for CCS). Again, one is left wondering whether the film makers know this and are lying, or simply do not understand the science that is being done in this area?

There is only one case in the US where fracking has triggered seismicity - in the Eola field, Oklahoma, which occurred in January 2011, 3 months before Preese Hall event, but was not reported as such until August 2011, after Preese Hall, and one case in Canada (British Columbia), where events occurred between 2009 and 2012, although they were not reported until August 2012, a long time after Preese Hall. So Preese Hall was the first reported incident of induced seismicity triggered by hydraulic stimulation for shale gas.

With respect to reporting of the earthquake and resulting casing deformation to the Energy Minister, there was no regulatory requirement to report casing deformation to him - this is the role of the HSE. Moreover, I think the actions taken were entirely appropriate - they ceased operations to allow a 6-month scientific study to be conducted, after which the results were reported for DECC, HSE and the rest of the world to read. While we're on the point, all of the casing deformation was within the production casing string, within the target zone of production - it was actually below the depths of the frack stages that triggered the seismicity. It poses no risk whatsoever to the integrity of the well. The figure below shows the well design - the deformation is the little yellow bar right at the bottom.

I think that's it in terms of my contribution to this piece of work. I'll comment briefly on the accusation of "mission-creep" in terms of chemical use - every chemical used in the UK must be permitted by the Environment Agency, and fully disclosed to the public.

One final point in closing: the go-to 'expert' for this film appears to be Ian R. Crane, an ex-oilfield-executive, who gets the final word as far as this film is concerned. I don't usually like to stoop to ad-hom arguments, but as Mr Crane seems to appear on an increasing number of anti-fracking pieces, it'll be worth your time having a look at his profile on RationalWiki, a website dedicated to uncovering cranks, conspiracy theorists, and pseudoscience. If this is the best figure-head that the anti-fracking movement can come up with, I would suggest they need to try a little harder.

UPDATE: I checked out the FrackFreeSomerset website to look for more information. According them, the film is not just "facilitated" by FFS, but in fact "produced" by them.

UPDATE (21/11/2013): The film maker himself has left a comment for me. He is correct to point out that I failed to address my comments of water use. In the film, I describe how much water is used for a single stimulation. Of course, the issue is cumulative effects over time if many wells need to be stimulated. The water use for an individual well (~10,000 - 50,000 cubic metres) sounds like a lot, but it must be placed in context. Between the 3 largest water utilities (Severn Trent, United and Thames), 1.7 billion liters of water are lost to leaks PER DAY. If water companies were able to improve on this by just 1%, we would have available an extra 17,000 cubic metres of water, that's enough water to frack a well every day. If water consumption is your concern, don't blame frackers, get the water utilities to fix their leaks (or at least 1% of their leaks).

Professor David Smythe's critique of Cuadrilla's drilling plans: A comment

Update (1.8.2014): It seems that the Geological Society are very unhappy about Prof. Smythe claiming to be a chartered geologist. The Geol Soc state that this title requires "proof of continuous professional development", with the clear implication that they do not believe Prof. Smythe meets this requirement.

Glasgow University are also unhappy about being associated with the professor. Paul Younger, Professor of Energy Engineering at Glasgow stated:

"He has published nothing on [shale gas] in any proper scientific forum — no doubt because he knows he would never get past peer review with his pseudo-scientific scaremongering. He falsely claims to be a chartered geologist. That’s fraudulent. It’s wilful untruth. I am concerned about the damage to the reputation of the university by someone who never fails to use his university affiliation.”

Original Article:
This post is a comment on the critique of Cuadrilla's Balcombe drilling plans made by David Smythe, Emeritus Professor of Geophysics at Glasgow University. The key points of this critique are as follows:

• Cuadrilla's interpretation of faults in the Weald basin differs from a potentially more parsimonious interpretation.
• Cuadrilla's interpretation omits smaller faults near to the well site, some of which might intersect a horizontal well.
• Seismic data is restricted to 2D seismic profiles of 1990s vintage, making it challenging to keep the horizontal well within the target micrite layer.
• If the well does stray out of zone, it may contact Kimmeridge Clay an important potential shale resource. It is suggested that the proposed micrite target is in fact a "cover story" for the targeting of Kimmeridge shales.
• Concerns are raised that if faults are intersected, they may act as "fast-track conduits" for surface water contamination, and/or lead to the triggering of seismic activity.

My comments are as follows:

There are indeed differences between the fault interpretations made by Cuadrilla and by Prof. Smythe. Without access to more data it is probably difficult to determine whose interpretation is the more accurate. This is a fact appreciated by all geology students who have ever done a mapping project: with limited data multiple interpretations are always possible. However, disagreements between fault locations are limited to the areas south of the Bolney well, which are not in Cuadrilla's license area. Within Cuadrilla's license area, the principal area of interest, both sets of fault interpretations are closely matched.

It is argued that the lack of 3D seismic data means that it will not be possible to keep the horizontal drill within the target micrite formation, and that it will not be possible to identify if/when small faults are intersected. This criticism ignores one of the key technological developments of the last 20 years, which is closely associated with the development of horizontal drilling. That technology is called "Geosteering" (also known as "Logging While Drilling"). For more detailed info on these techniques I'll have to hand you over to google for now, but this article provides a decent explanation.

Essentially, geophysical measurements are taken continuously at the drill tip. This data tells drilling engineers what rocks they are in. They use this to guide where the drill goes, allowing them to stay within the target formation. If you read the linked article, you'll note that it even allows engineers to see when they've intersected faults. Geosteering is common practice when drilling horizontal wells in the Barnett and the Marcellus, the two most significant shale plays in the US.

I'll include here some comments on a couple of issues raised on Prof. Smythe's website, which don't appear in the linked slides but form a key part of the conclusions outlined above. In the comments on faulting in US and European basins, he argues that "faulting is almost non-existent in the US basins". This isn't the first time I've heard this suggestion, and I don't know where this meme has come from. The eagle-eyed among you will have spotted this comment in the linked Geosteering article:

"In some areas in Pennsylvania, the geology is very complex across some of our leases," Collins noted. "There are very large thrust faults"

I've even had the pleasure of seeing them myself - they tend to show up in microseismic data. You can see an example in this paper, and below is another microseismic dataset clearly showing the interaction of the stimulated stages with a fault:

(image courtesy of Microseismic Inc)

Faults are clearly not "almost non-existent in the US basins". Prof. Smythe criticises the well-known Warpinski-Fisher paper that looked at hydraulic fracture height growth for its failure to include fault data. However, the Warpinski-Fisher paper explicitly includes data from examples when hydraulic fractures have intersected faults (see slides 7 and 11 in this presentation, for example), providing clear evidence that stimulation does not create pathways from deep-lying reservoirs to shallow potable aquifers, even when faults are present.

I would also like to address the comment that "faults do not normally act as seals". This is a misleading comment. It is true that when risking a potential reservoir trap identified on seismic data, the observation of faulting on the top of an anticline would present a risk, because with seismic surveys alone it is difficult to tell whether a fault might be sealing or not, and so whether there might be hydrocarbons present, of if they might have all leaked away over geological time.

However, it is not true to claim that "faults do not normally act as seals". Fault traps - where the geometry of faults and reservoir units serve to form a trap, instead of the traditional anticline domes - are a common method of trapping oil and gas. If that last sentence didn't make sense, there are plenty of pictures on google. Fault compartmentalisation - where sealing faults break up a reservoir and prevent fluids from flowing to the well - is a common problem in conventional reservoirs. You can read about a case example here. A particularly pertinent quote is "clay-rich lithologies (i.e. shales) are likely to reduce fault zone permeability (i.e. provide better fault sealing) more than clay-poor lithologies". We know from Conoco's drilling in the 1980s that oil is present in the micrite beds underneath Balcombe. This oil has been trapped there for hundreds of millions of years. This would suggest that, even if the Paddockhurst Park Fault does intersect the target micrite formation, it is not providing a transmissive pathway to flow.

Finally on the issue of induced seismicity. It is a misconception that if a hydraulic stimulation intersects a fault, it will inevitably create a "larger" earthquake (i.e. one that might be felt by humans at the surface, such as at Blackpool). Again, this is not the case, as documented in the microseismic examples above. It is not uncommon for stimulations to intersect small faults, yet incidences of felt seismic events are extremely rare amongst hundreds of thousands of stimulations. Although in some cases event magnitudes have increased slightly upon intersection with a fault, they remain well below the threshold that could be felt at surface. For hydraulic stimulation to trigger detectable seismic events, the stress state on the triggered fault must already have optimal orientation and magnitude - that is to say the fault must already be close to it's failure state. The majority of faults likely to be intersected during stimulation will not meet these criteria, hence the lack of detected seismicity during operations in the USA, and hence the conclusion by the expert report into the Blackpool earthquakes that they represent "exceptional" circumstances.

That said, as with pretty much any subsurface activity, there is a small risk of triggering small seismic events that should be considered. DECC have already put into place strict seismic monitoring guidelines to ensure that there is no repeat of events near Blackpool. Bristol University already has seismic monitoring stations deployed around Balcombe.

I agree with some of the more general suggestions made by Prof. Smythe: more geophysical surveys will enable us to better understand the subsurface geology. This is beneficial all around - enabling operators to maximise their production efficiency while regulators can minimise any environmental risk. I expect that as potential shale gas developments move through exploration into preliminary production phases, we will see more and more geophysical data being collected (as we have already seen a new 3D seismic survey collected on the Fylde). However, I strongly disagree with Prof. Smythe with respect to current operations at Balcombe - they are not likely to pose a significant risk in terms of fluid migration from depth or from induced seismicity.

Update (04/09/2013): Another example of hydraulic stimulation interacting with faults without adverse impact is the NETL hydraulic fracturing study, which received a lot of coverage last month. In this study, researchers injected tracer chemicals along with the fracking fluid. The shale layers were at 8,000ft depth, and an overlying layer at 5,000ft depth was monitored, looking to see if the tracers appeared in this overlying formation. The microseismic data from this operation has not yet been published, but reports seem to indicate that the stimulation intersected a fault. Even so, there was no evidence for the tracers in the overlying formation, nor were any larger-magnitude seismic events triggered.

Update (05/09/2013): Of course, I've missed perhaps the best example of stimulation intersecting a fault, in fact probably the best known one: the operations near Blackpool that triggered seismic events in 2011. This is the worst-case scenario - a stimulation intersecting a fault that is optimally oriented in the present day stress field, and close enough to failure that the stimulation is capable of triggering some of the largest seismic events ever seen during hydraulic fracturing in shales. Yet even for this worst-case example, the operators were able to produce gas from the reservoir, without any suggestion of shallow groundwater contamination from this fault.

Seismometer deployment to monitor drilling at Balcombe

If you follow me on twitter as well as reading my blog will know that I go by the name @TheFracDoctor. This choice of name was influenced in part by the fact that I had recently finished my PhD, and as anyone who has experienced the flush of post-viva success, there is the temptation to put the word ‘Doctor’ in front of everything. 

But also it is the role of the doctor to monitor the health of his patient, and that is how I see seismic and micro-seismic monitoring – a tool to monitor the health of a fracture stimulation.

In the last few weeks I’ve had the opportunity to do this for real in the UK for the first time: deploying seismometers around Cuadrilla’s planned Balcombe well. I’ll note right now that the current Cuadrilla plan is to drill into limestone for conventional oil, with no intention of hydraulic fracturing at this stage, but we wanted to get some experience deploying seismometers for this sort of situation.

However, Balcombe is the site of the now-infamous ‘Battle of Balcombe’ and has been at the center of much debate of unconventional gas extraction (these stations were put in a month ago, well before the events of last week). Of particular focus has been the risk of seismic activity to the Balcombe Viaduct.

This spectacular bridge, built in 1841, still carries the main London-to-Brighton rail line:

After the seismic events during stimulation at the Preese Hall well, Blackpool, concerns were raised about the possibility of similar seismic activity affecting this bridge. So we decided to deploy seismometers while they drill their Balcombe well. There are no plans for fracking at the moment, so we’re not expecting any seismic activity. Our main aims were (1) to get some experience deploying seismic stations in rural England, and (2) to record baseline activity prior to drilling.

Baseline data will help us understand the noise levels in the area, which will determine the size of the smallest earthquake we can detect – obviously the lower the noise level, the smaller event you can detect. The current traffic light scheme for seismicity proposed by DECC requires events as small as M0.0 to be detected. We want to see if this will be possible with a small array of 4 surface seismometers (we will compute the expected shaking from an M0.0 event, and see if it emerges above the noise).

Baseline data will also enable to see what changes (if any) drilling activities produce.

I will post updates as and when we collect and analyse the data. For now, this seems like a good time to share some holiday snaps, so you get to learn about what we do when we deploy seismometer arrays, and what they look like.

Firstly, here’s the piece of kit that we use: a Trillium 120 seismometer:

This is a fairly standard piece of kit in earthquake seismology, capable of measuring the vibration of the earth across a wide frequency, from long periods (up to 60 seconds) up to the sampling rate of 250Hz.

To reduce the noise from things like wind and rain, they need to be buried 50cm or so under ground. Which means you have to dig a hole. I used to work on building sites during my A-levels, and I was delighted when I got my degree, knowing that my days of manual labour were over (because digging holes all day is TOUGH work). Yet, a masters degree and PhD later, and here I am digging holes all day!

Once the pit is ready, the seismometer is carefully placed into the hole:

The batteries and data logger go in the steel box next to the pit. We run cables, insulated inside fire hose, from the instrument into the box:

 

Initial covering for the instrument, to further minimise surface noise, is provided by its ‘lid’, the black dome you can see below:

Once we are happy that the instrument is working properly, we fill the hole (being careful not to dislodge the insulating cover from the instrument. We lay a waterproof sheet just below the surface, and pile turf on top as a final covering:

Finally, we put a small chicken-wire fence around the station. This is more of a deterrent than anything else: it’s not likely to stop a marauding cow, nor is it really capable of keeping out a determined rodent (animals chewing on loose cables is a real problem in many seismic deployments):

And after all that (a couple of hours work at least), you have your seismic station:

We placed 4 stations in total, including one a few hundred yards from the viaduct:

As we set this station up, we could see the vibrations from the trains going past every 5 minutes recorded on our seismometer. It will be interesting to see what caused more vibration – the Preese Hall earthquakes or the train going past at a distance of a couple of hundred yards. After all, the initial concern at Balcombe was that seismicity would trouble the bridge – even though this is a bridge that is being shaken by an express train every 5 minutes.

We enjoyed our two days in the picturesque British countryside, and we were very glad we missed all the protestors. Fortunately, the stations are all a couple of km at least from the London Road protest site, and accessible from other roads, so that’s a gauntlet we won’t have to run. The only disturbance we saw was from these guys:

So there’s our seismic deployment in Balcombe. More to follow once we’ve analysed the data.

Bristol's shake table

Shake tables are used to simulate the effects of earthquakes on structures. Engineers use them to simulate the effects of earthquakes on structures, so that they can design buildings to withstand shaking.

You can program in the earthquake of your choice, put your structure on the table, and see how well it does. Today I got to visit the Bristol Engineering Dept shake table. Here's some video:

Induced Earthquakes in the USA, and some implications for CCS

Here's a recent BBC report on earthquakes induced by oil and gas activities in the USA. As can be expected, the twitter/blogo-sphere has been lighting up over this in the last few days. For me the biggest surprise is that this has only come up in the wider media in last few days: induced earthquakes have been a key topic of discussion among geophysicists for a couple of years now. The USGS has noted an increase in medium-sized earthquakes in the last decade:

The black line shows the total number of earthquakes in the midcontinent USA (excluding the very active San Andreas fault and other active parts on the west coast) greater than M3 since 1970: you can see the increases as the line gets steeper.

The oil industry likes to dispose of waste-water by injecting it into deep-lying saline aquifers. However, it has been well known since the Rocky Mountain Arsenal in the 1960s that deep fluid injection can trigger earthquakes. It is argued that the increase in oil industry injection activities in the last decade has been the cause of the increase in the numbers of earthquakes.

This remains under debate - could the increase be simply that, as more (and better) seismic monitoring networks are installed, we are detecting more earthquakes than we did in the past. The latest news story is a case in point. The paper in Geology attributes an M5.7 earthquake in Oklahoma to injection of waste-water. The Oklahoma Geological Survey has subsequently released a rebuttal stating that as far as it is concerned, there is not enough evidence to tie the quake to injection activities (strangely enough, the OGS rebuttal hasn't been given much of a look-in from the media).

Nevertheless, I think that it inarguable that, in certain cases at least, fluid injection has triggered earthquakes with magnitudes from about M3 to M6.

This brings me to a couple of asides. Firstly, following on from my last post about bad media reporting of these issues, many reports attributed the quake to injection of waste-water from fracking. This is not the case - the waste water in this case came from conventional oil production. This harks back to an older post I made about the relative risk profiles from fracking in comparison to conventional oil and gas. The need to dispose of large quantities of contaminated waste water is not a new, fracking-related problem in the oil industry. If you are opposed to fracking, you must presumably be opposed to all oil and gas related activity.

Secondly, M5.7 is a large earthquake. It is about 100,000 times larger than the quake induced in Blackpool by fracking. It is larger than any earthquake ever recorded in the UK. Perhaps only a few historical earthquakes in the UK have been of a similar size. An M5.7 triggered earthquake here would be serious news.

So, can we get an estimate of what earthquake magnitude might be triggered by our various activities? Art McGarr, a venerable (and venerated) and highly experienced geophysicist with the USGS has made an effort to do this. McGarr cut his teeth in the 1970s looking at mining induced seismicity, where he noticed a correlation between the total energy released during rock extraction and the volume of rock extracted. He developed the so-called McGarr equation:

Sum(Moment) = G dV

The sum of the released seismic moment equals the volume change (dV) multiplied by the shear modulus (G). It should be noted that this equation is based on empirical observation only. It has subsequently been applied to fluid injection (or mis-applied, some would say, as there is no obvious basis for arguing that physical processes during fluid injection should match those during rock removal (mining)), where dV becomes the volume of fluid injected.

More recently, McGarr has been looking at earthquakes attributed to fluid injection. This includes waste-water injection as discussed above, as well as geothermal activities and, of course, fracking. He has developed the following plot:

Each + represents an injection-induced seismic event. Unfortunately for any non-geophysicist readers, McGarr has given the earthquake sizes in moment, rather than magnitude, but 10^12 is about M2, 10^15 is about M4, 10^18 is M6. I've not found out what all of McGarr's abbreviations are, but

• BUK is the Blackpool earthquake
• RMA is the quake induced by fluid disposal at the Rocky Mountain Arsenal
• BAS is the Basel (Switzerland) earthquake caused by geothermal activity
• STZ is an earthquake caused by geothermal activity at Soultz, France
• RAT (several of them) are earthquakes in the Raton Basin (Colorado) associated with waste water injection
• POK is the Oklahoma earthquake discussed in this blog

You can see a general correlation between the maximum magnitude and the injection volume, following a McGarr-esque equation, replacing the sum of the moment by a maximum magnitude: Mmax = GdV. It should be remembered that this line appears to be describing the MAXIMUM POSSIBLE magnitude. There are over 150,000 waste-water injection wells in the USA, only a tiny fraction of them have caused detectable earthquakes.

So how does this apply to the UK? The first thing to note is that deep injection of waste fluids is not allowed in this country, so we can strike this risk off immediately. What about fracking? A typical frack stimulation uses about 1000 - 5000 metres cubed of water - that's ~10^3. This leaves us with a maximum induce-able moment of ~10^13 (or a magnitude of about M3). We get 30 or so M3 events in the UK every year, so inducing a few more due to fracking isn't going to make much difference.

What about CCS? Carbon capture and storage is a key plank in the UK's CO2 emissions reductions plan. All well and good, but CCS involves the injection of very large volumes of fluid into subsurface aquifers. Could this trigger earthquakes?

I've modified McGarr's plot to add the injection volumes of Sleipner and In Salah, two of the foremost CCS projects currently in operation (as well as changing the scale from moment to magnitude to make life a little easier for non-geophysicists):

You can see that, following the McGarr plot, Sleipner and In Salah have the potential to trigger earthquakes of M5 or larger! Of course, they haven't: Sleipner has barely done anything, while In Salah has triggered at most an M1 event (so small you can't feel it without the aid of sensitive seismometers). The McGarr plot tells you the maximum possible magnitude, not what magnitude you will get. Hence why I have shaded in the area under the line: you could get an event on the line, or anywhere under the line.

Still, I find the potential for induced earthquakes from CCS to be worrying. I think this has been under-appreciated by the UK CCS community. There is a clear need for further study on why most injection sites do not produce seismicity, but a few do? What is it that is different about these sites, and how can we identify this in advance, and only select sites that won't trigger events during CO2 injection. At the same time, we can quickly see that the earthquake risk from fracking has been hugely overplayed in comparison to the risks posed by other activites (geothermal, CCS, waste-water injection, mining, and even hydroelectric energy).

My visit to Glastonbury

Last week I had the pleasure of visiting Glastonbury, a small town in Somerset best known for its tor and its music festival. Glastonbury Town Council has preemptively declared itself to be 'frack-free'. Much like Frome's similar decision last year, this is more a symbolic gesture, because (a) it's not clear that there is any unconventional gas to be had from around Glastonbury, and (b) if there were, it is unlikely to be developed for many years.

The decision was not a unanimous one. Some councillors felt that the decision had been rushed, having heard only of the negative sides from Frack Free Somerset. Jim Barron, one of the dissenting councilmen, pleaded in the local paper for a more evidence based discussion before any decisions be taken.

As a result, I was asked to come down to Glastonbury one evening after work to give a presentation to the council. You can download the presentation that I ended up giving from here. You might as well read it in full, but here's a potted summary.

I began by explaining what shale gas is, why it is different to conventional gas, and why hydraulic fracturing is necessary. I followed this by explaining the process, including a time-lapse video of a well being drilled and fracked, and an animation showing how microseismic events are used to image where the stimulated fracture is going. I gave a short overview of existing UK onshore oil/gas operations, including the fact that fracking has been done over 200 times in the UK since the 1970s.

I then outlined what I see as the potential issues relating to unconventional gas extraction: water usage, earthquakes, water contamination, air pollution, and surface impacts. The first, water usage, can be quickly shown to be a red herring: the water lost by SouthWest Water through leakage every day would be enough to frack more than 30 wells. I talked about the Blackpool earthquake, discussing how event magnitudes work (and that the event in Blackpool is so small that most of my real-earthquake-studying colleagues wouldn't get out of bed for something 10 times the size), and looking at evidence for fracking-induced earthquakes elsewhere (of which there are a handful in Canada, but none in the US).

Water contamination is perhaps the major issue for fracking. It is clear that there have been some cases of methane contamination through wells, and of chemical spills at the surface. I listed some of the key incidents taken from this report. However, it is important to point out that where methane leakage has occurred, it is inevitably due to shoddy practice from the drillers: poor or incomplete casing and/or missing cement. Equally, it should be fairly easy not to spill chemicals on pads at the surface, while open tailings ponds (often the most common source of surface contamination) are not allowed in the UK. It is most important to consider the context of these incidents: for example, the Groundwater Protection Council estimate that less than 0.1% of wells have seen a problem.   

With respect to air pollution, I showed a number of studies from both Pennsylvania and Texas, which do not show increases in benzene, ozone or volatile organic compounds (VOCs) before and after drilling. I then looked at a study of employee health statistics for the oil and gas industry in comparison to other sectors. If drill pads are unhealthy places to be, with dangerous chemicals being pumped into the air, then surely the employees should be getting the sickest, given that they might be on site 6 days a week for months on end. In fact, sickness rate in the gas industry is pretty consistent with national average rates, and a lot lower than many other industries.

To demonstrate the surface impacts of shale gas extraction, I showed some photos of what the rigs look like during drilling (on site for a month or two), and what the pads look like once the well is completed, and talked about pad spacing (minimum 2 - 6km as an approximation), as well as pointing out other impacts like new pipelines, and the truck journeys to and from the pads.

I then talked about the public debate around fracking in the US, pointing out that it has become highly polarised, with protest groups, but then anti-protest groups who protest the protest groups. I also showed the data from a Pittsburgh public opinion survey that showed that generally fracking does have more support than opposition (although perhaps the opposition is more vociferous).

Finally, as I like to do, I compared the risks from fracking to the risks from conventional gas extraction. To me at least, if you are opposed to fracking, you should be opposed to all hydrocarbon extraction, so I posed the question to Glastonbury's councilmen: take the scary boogey-word 'fracking' out of the question, and ask what would you do if there was a large conventional gas field discovered under Glastonbury. What would you do?

BGS shale gas estimates: an update, and other London meetings

I've just got back to Bristol from a very interesting few days in London, first at an AAPG conference on induced seismicity, followed by a BGA conference on geophysics and new energy challenges.

The first item of note was a talk given by Mike Stephenson of the BGS on UK shale gas. He didn't mention any numbers from the upcoming BGS resource estimate, so I took the trouble of asking him for a comment on the numbers published by the Times last weekend. In his words: 'they've simply made those numbers up'.

Fair enough, I guess that'll teach the likes of me to go jumping on every number you see in the press. Of course, he'd have to say that, as it would be embarrassing for the BGS to have had a leak, but either way hopefully the BGS will get around to giving us some figures in the very near future (it was originally supposed to be released in January, and we're still waiting).

I also got to have a good long chat with Huw Clarke, who is Cuadrilla's chief microseismic guy. One thing that noone has really talked about much is the flow rates from Cuadrilla's fracked well.

We've all talked plenty about the earthquake they produced, but we've all forgotten that they successfully completed 6 stages of fracking, and have tested the flow rates they got back after the frack. Whether or not the flow rates are sufficient to be economical will be a key part of whether shale gas extraction will happen in the UK.

Of course, Cuadrilla's flow rates are highly highly highly commercially sensitive, and there's no way Cuadrilla are going to tell anyone what they are. But it's interesting to note that, after having measured the flow rates, Cuadrilla have been happy to pay for a 3D seismic survey, the installation of a dense array of permanent geophone sensors, and a whole heap of PR on the side (as well as leaving the drilling rig parked in Lancashire when it could be drilling holes anywhere in Europe).

These aren't the kind of things you'd do if you have concerns about the economic viability of the gas flow rates from the shale formation, which of course implies that Cuadrilla probably think they're sitting on some pretty significant resources.


Other things that came up in these conferences? One of the major themes can be summarised as 'Induced seismicity, friend or foe', or 'Induced seismicity, the good, the bad and the ugly'. Of course, if you've met many geophysicists, you'll know what the 'ugly' is describing.

Whenever you inject fluids into, or take fluids out of, a reservoir, you change the stress state. This will almost inevitably induce earthquakes. The majority of these are so small (M-3 to M-1) that they can only be detected with sensitive seismometers placed right next to the target of interest. We geophysicists locate the microearthquakes, using them to learn about the stress state and fractures in the reservoir, enabling operators to improve the safety and economic viability of their operations. This is the good, or friend, part of induced seismicity.

However, every so often, as at Blackpool, operations create a larger event, which can be felt by the public. This tends to cause a lot of alarm, and the operators start to feel the regulators breathing down their neck. This is induced seismicity the bad, or the foe.

The big problem is that we're still not really very good at predicting when we'll just get small events, and when we'll get larger ones. Clearly the presence of a pre-existing fault is needed for a larger event. But many operations occur right next to faults without triggering any seismicity.

So it seems we still don't know why 99% of our activities don't trigger felt seismicity, but some do. There are probably about 150,000 waste-water injection wells in the US, and only about 10-20 have induced felt seismicity. There have been hundreds of thousands of fracking stages completed in the US, yet only one in Oklahoma, one in Blackpool, and a few in British Columbia, have triggered felt earthquakes.

So this was probably one of the key aspects emerging from these two meetings: the need to develop improved geomechanical modelling of reservoir activities (whether it be fracking, carbon dioxide injection for CCS, or waste-water injection), so we can predict whether we're likely to trigger a larger earthquake on a fault. So if you are a budding geoscientist or engineer deciding what direction to pursue, I'd recommend looking in to this, because improvements in this area will be really significant for a lot of industries.

Ed Davey's Written Statement on Shale Gas: Highlights

Well done if you got to the end of my previous post, Ed Davey's full statement on shale gas extraction. In case you didn't, I've selected the highlights with respect to induced seismicity:

I have concluded that appropriate controls are available to mitigate the risks of undesirable seismic activity. Those new controls will be required by my Department for all future shale gas wells.

 So any new regulations will be applied to all wells.

the amount of energy likely to be stored in these faults is not large, and the largest earthquake likely in this area from such a cause is assessed at magnitude 3.

Seems reasonable that the maximum likely quake is the same as those typically seen in background rates.

Operators will first be required to review the available information on faults in the area of the proposed well to minimise the risk of activating any fault by fracking, and required to monitor background seismicity before operations commence. Real time seismic monitoring will also continue during operations, with these subject to a “traffic-light” regime, so that operations can be quickly paused and data reviewed if unusual levels of seismic activity is observed.

Very interesting, and good news for service companies. The 'available information' on faults in the area must surely imply 3D seismic surveys prior to any fracking. Good news if you are WesternGeco et al. Also, real time (micro)seismic monitoring is required. Good news for microseismic companies (and researchers like me).

Real-time recording of earthquakes during and for 24 hours after each stage of the frac will be analysed to look for abnormal induced events amidst the normal background seismicity.

Again, more good news on real time monitoring. I'm not sure how we'd classify an 'abnormal' event though.

Operators will also be required to monitor the growth in height of the frac away from the borehole. This will allow the operator to evaluate the effectiveness of the frac, but also ensure that the actual fracture is conforming to its design, and that it remains contained and far away from any aquifers.

To monitor the growth in height of the fracture will require accurate microseismic monitoring, with depths in particular being well constrained. This means deployments of significant arrays. Chucking a couple of broadband seismometers nearby will not be sufficient - large dense surface arrays or downhole arrays will be required.

the remedial action level for the traffic light system (that is, the “red light”) will be set at magnitude 0.5 (far below a perceptible surface event, but larger than the expected level generated by the fracturing of the rock).

Cuadrilla's 'traffic light' system will remain in place. This states that fracking must stop if an event larger than M0.5 is induced. In principle this is a sensible limit. However, it throws up questions of it's own, because in science there are such things as error bars. There's no such thing as an M0.5 event. There's M0.5 ± some value. There are also several different ways of computing magnitude, which don't always produce the same value. The question is then: do you take the highest possible value, the lowest possible value, or some mean (most probable) value as the point at which the traffic light red is exceeded?

And who gets to decide? Industry themselves? Probably not the wisest move. DECC themselves? Do they have the expertise - not really? <begins shameless self promotion> how about independent academic experts?< /ends shameless self promotion>

All told, good news for shale gas companies looking at the UK, but even better news for service companies (and researchers) with experience in microseismic monitoring!  

The Day Job.....

With the quality of writing on offer, many of you might helpfully suggest that I don't give up the day job. Don't worry, I don't intend to. Instead I thought my blog this week would be a good chance to give you a flavour of what my day job actually entails.

My motivation for doing so: I've just had a paper accepted (well almost, a few minor corrections to do) to Geophysical Prospecting, one of the major international applied geophysics journals. Link to the paper here, in its almost finished form (it'll be copy-edited and re-formatted by GeoProsp before they publish). It's also a good opportunity for me to practice explaining my research to a more general (although still highly intelligent, and rather good-looking, I've no doubt ;-) ) readership.

In this paper, I develop a method to improve our ability to image the fractures formed during hydraulic fracturing for shale gas. This is important for both the operators, who want to know as much about the fractures as possible to maximise production, and for regulators, who want to make sure the fractures create will not provide a pathway for fluid contamination. So how does my method work?

You'll remember in this post I talked about how geophysicists deploy geophones in boreholes to listen out for the popping and crackling of the rock as it fractures, and we use the recorded data to identify where the fractures are going. This is pretty standard, the bread-and-butter for many service companies who offer variants on this technology.

The new bit, where my colleagues at Bristol and I come in, is to realise that as the seismic waves travel from the source (the fracture) to the geophone, they will be travelling through previously fractured rock. Therefore, polarisations and arrival times of the recorded waves will be controlled by the properties of not only the rock, but also of the fractures. In particular, we measure splitting of shear waves. When the S-waves move through fractured rock, they become split into faster and slower waves with a 90 degree polarisation difference. We measure the fast wave polarisation, and the delay between fast and slow waves. These measurements can tell us about the properties of the fractures.

In particular, in this latest paper we show that the S-wave splitting measurements can tell us about the ratio of normal to tangential compliance of the fractures. In layman's terms, that is the ratio of how easy it is to squeeze the fractures versus how easy it is to slide the fractures. Lab experiments have seemed to show that the presence of proppant (the sand particles injected to 'prop' the fractures open) will increase the normal to tangential ratio, so if we can see changes through time, this can tell us where the proppant has gone, allowing us to predict where the greatest flow will come from during production (the better 'propped' a fracture is, the better it will flow).      

The key results picture is below:

This shows the frack-job through time. The bottom panel shows the fluid injection rate (blue), the proppant concentration (green) and the resulting microseismicity (black) through time. The frack-job is conducted with 4 phases - 3 initial injections to create fractures, and a final phase where proppant in introduced. The upper panels show the results of our S-wave splitting measurements. Of most note is the 2nd panel, for Zn/Zt - the normal to tangential compliance ratio. You can see it is low during the initial fracture stages, but after 13:00, when proppant is injected, it increases to values almost as high as 2.

Like all good scientists, we are cautious in our conclusions. We think that this increase is most likely showing the proppant entering fractures. However, further work is needed to verify our findings, and to see if this method can work on other frack-job datasets. However, the initial findings are promising. If this method takes off, it'll allow operators to gain a better understanding of the fractures they create during fracking operations.

Anyway, I hope you've stayed with me up until this point, dear reader. Any questions - do pop them in the comments below. Talking about one's actual research to a general audience can be quite tough, but I hope I've been able to convey what my day-job entails. I promise to talk about something more exciting next time.