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.

Shale must be careful who its friends are

Wherever you read a media report on shale gas these days, it will inevitably be described as 'controversial'. While Nick Grealy at nohotair.co.uk pulls out his hair over what is media hype rather than sound science, there can be little doubt that shale has a public image (or at least a media image) problem.

This cuts deeper than the deep greens camped outside Balcombe making outrageous claims that the water there is already poisoned, or that 2 recent earthquakes in the Irish Sea were due to fracking. A wider, more rational concern is that shale "is just another fossil fuel, locking us into a fossil fuel future". I work in a geology department: most of my colleagues are geoscientists, while some study climate change. In general, when they ask me about shale gas, their questions are not about water or earthquake risks, but about climate change.

This concern arises, in part, because of who the public sees as the main cheerleaders for shale gas. In recent weeks, we have seen the case for shale gas being made by the likes of Lord Lawson, Lord Howell (he of the "desolate north-east" comment), George Osborne and the like. Whatever actual views they might hold, the public do not see them as people who can be trusted to put environmental issues before financial gain.

Is it a surprise then, that with protagonists such as these it is difficult to convince the public that shale gas extraction could actually be a good thing in terms of greenhouse gas emissions? Shale should be careful who its friends are.

Instead of hearing from Messrs Lawson, Howell and Osborne, perhaps we should hear more from the Environmental Defense Fund, who have realised that rather than getting themselves arrested for protesting about shale gas outside an limestone-oil-drilling operation, which is a bit silly, the productive thing to do is to work with the industry to ensure that the benefits of shale are maximised, and any negative impacts are minimised.

Perhaps we should hear more from the likes of Transition Dorking, an environmental group prepared to consider the benefits of shale.

Will shale gas extraction lock us into a fossil fuel future? Perhaps we should hear more from the State of Texas, the undisputed home of shale gas. Texas is also one of the leading states for renewable energy generation (mainly from wind), trailing only the rainy and mountainous (and therefore ideal for hydroelectric) Pacific Coast states. Texas is the wind capital of the US (perhaps it's all the fantastic BBQ food).

This boom in renewable energy development occurred simultaneously with the shale gas boom. It may just be coincidence. However, in the current absence of efficient and large scale energy storage options, the ability of gas turbine power plants to provide quickly-dispatchable power has been crucial in coping with wind intermittency.

The economic benefits provided by shale development are no doubt helpful as well - a state with decent finances is surely more likely to be prepared to spend more in developing renewable energy. We like to say that we should be investing more in renewable energy. Well, to invest, you need to have money to spend.

Texas shows us that shale gas development need not crowd out renewable developments (and in fact may be beneficial). However, our current government is seen to be very pro-shale, and somewhat ambivalent to renewables, hence the public concern in this regard. I think the government is missing the chance to show that it is committed to both, and that they can work together.

Despite recent announcements of tax cuts to stimulate early development, the exchequer can still expect to take a lot of tax from shale gas extraction. Why not declare that a certain portion of that tax take will be ring-fenced, to be spent only on research, development and demonstration of alternative energy options (be they renewable, next-gen nuclear or fusion)?

That, in my view, would be the ideal path to take - showing that the government doesn't view shale as the be-all and end-all, but a necessary step on the path to a better future, and that there's more to shale development than is presented by Howell, Lawson et al.

Shale gas and "fracking": FAQ

What is shale gas?
Shale rocks are generally dense and black-coloured, formed from mud deposited at the bottom of past oceans, now solidified into rock. This mud is rich in un-decayed organic matter - that's what gives shales their black colour. When heated, the organic matter is transformed into oil and gas.

Once it has formed, some of this oil and gas is able to move out of the shale layers, rising through overlying strata, where it may become trapped in sandstone or limestone layers. This oil and gas is what we consider to be 'conventional' reservoirs, where we have usually looked for oil.

However, it has always been known that much of the oil and gas formed during burial remains behind, trapped in the shale layers. Compared to sandstones and limestones shales tend to have lower porosity, making it harder for the oil and gas to move about through the shale. This means that it is harder to extract gas from shale than from conventional reservoirs where the fluids can flow more freely.
 
So how is shale gas extracted?
Firstly, a well is sunk, which travels vertically through the overlying strata. When it reaches the shale layer, it turns sideways, drilling horizontally. Modern wells are capable of drilling over 10km horizontally: such wells are called 'extended reach laterals'. This part is absolutely no different to conventional drilling.

Once the horizontal well is drilled, it must be hydraulically stimulated, or as it has become known, "fracked". The horizontal well is "fracked" in portions, stage by stage every few hundred meters or so, meaning that a 2km lateral well might need 10 to 20 stages. For each stage, the targetted section of the well is sealed off, and water is pumped down at high pressure. This water will contain about 1% chemicals that make the stimulation more efficient: surfactants (basically like detergent) that make the water more 'slippery', so less pressure is needed to pump it; and viscosifiers, that help the water carry proppant (more on that in a moment).


The pressure of the water is sufficient to open up pre-existing fractures in the rock, and to create new ones. These fractures are important, because they provide a pathway for the gas to flow out of the shale rock and into the well. Above I pointed out that it is difficult for oil and gas to flow through shale rocks. It is the fractures that allow them to flow into the well. Towards the end of the stage, proppant is pumped with the water. Proppant is usually just sand and gravel, although ceramic beads can also be used. The proppant is pushed into the fractures that have been created, literally 'propping' them open, ensuring that the gas can continue to flow.

Each stage takes a few hours of pumping, so to "frack" all the stages of a lateral might take a week. Once that is completed, the well is ready for production. A small 'Christmas Tree' valve is placed on the top of the well, and the gas may continue to flow for years without any further intervention.

There's suddenly a lot of media fuss about fracking. It must be a new technology, right?
Wells were first hydraulically stimulated in the 1940s. It has been a standard tool in a driller's toolbox for a long time. Horizontal wells are in fact far newer, really only becoming common in the 1990s. Some would argue that the current developments have more to do with horizontal drilling than they do hydraulic stimulation. However, even with these developments, many geologists felt that it would never be possible to extract gas from shales at economic rates.

George Mitchell, a Texan, persevered through the 1990s, improving the technique, to show that it was in fact possible, and the shale revolution was born. Since then, a drilling boom exploded as American companies realised they didn't have to look abroad, or in the deep and treacherous waters of the Gulf of Mexico, because huge volumes of oil and gas were to be found under Texas, Colorado, Pennsylvania and now 30 other US states.

So hydraulic stimulation, or "fracking", is a very well established technique. Horizontal drilling, just as essential to shale development, but much less talked about, is newer, developing in the 1990s.

However, to extract gas from shales requires more fractures than in a conventional reservoir, as they are initially less permeable. Therefore, the volumes of water being injected for shale are typically larger than that used previously in conventional reservoirs. So while current developments are not using new technology, it does represent a scaling up of that technology.

I've heard about scary-sounding chemicals contaminating water supplies. Is this true?
Opponents of fracking sometimes talk about the 500 toxic chemicals needed to "frack". I don't think any stimulation needs 500 different chemicals: that's probably the total number used in the history of the technique, not the number used for a single stimulation.

The two main chemicals used are surfactants (found in most soaps/detergents) and viscosifiers (typically guar gum, used in many food products). While not hideously toxic, I wouldn't want to drink water contaminated with surfactants and the like (who'd want to drink the sink-water after they've done the washing up). In addition, the water injected during "fracking" comes into contact with the deep shale rocks. These sometimes contain heavy metals and salts, which may also enter into the "fracking" fluid.

The most obvious way for these chemicals to enter groundwater is if they are spilled on the surface. There is an example from Louisiana where 17 cattle died after undiluted KCl was allowed to spill off of a drill pad. Many of the reported issues in the US are due to the ponds used to hold the waste fluids: open pools lined with plastic. The lining of these ponds has been known to tear, or if it rains heavily they can overflow. Ponds like this are not allowed in the UK for exactly these reasons. In the UK waste fluids must be stored in double-lined steel tanks: this is a major difference between drilling in the UK and the USA.

Safe management of fluids on the surface should be standard practice for all oil and gas operations - you can read here all the precautions Cuadrilla have taken at Balcombe, layer upon layer of protection to ensure that no substance on the drill site is allowed to leak.

The secondary concern, of course, is what happens when the fluid is injected into the ground. "Fracking" takes place well below the water table, typically at depths of 2 - 4km (most potable ground water is found within a few hundred meters of the surface). So there is a lot of solid rock between where the fluid is injected and any potable water.

For the injected fluids to contaminate groundwater, two things are required: (1) a path (such as faults and fractures) along which these fluids could migrate, and (2) a force to push these fluids along this path.

If there were an easy path allowing fluids to move upwards, then the oil or gas, more buoyant and more mobile than water-based "frack" fluids, would have already travelled through these paths during the 200 million years of geologic history for which the gas has been trapped. Therefore, the fact that the gas is still trapped there to start with tells us that such paths are unlikely.

As for a driving force to push the fluids along such a pathway, should it exist? The water-based "frack" fluids, with their various additives, are of a similar density, or perhaps even more dense, than the brines that fill non-gas-bearing rocks at these depths, and of course much denser than oil and gas. Therefore, they will tend to sink downwards, rather than rise upwards. There is no driving force to push the "frack" fluids back towards the surface.

So we have no pathway, and no driving mechanism, to cause injected "frack" fluids to rise upwards towards potable groundwater sources. This was the conclusion of a recent study into the possibility of hydraulic communication between shale layers are depth and shallow groundwater bodies, finding it "physically implausible".

That's all fine in theory, what about the evidence? Well, a number of studies have been done on water quality in shale areas. Only one, a recent paper by an Arlington group has suggested any kind of link between drilling and contamination by "chemicals". They found a correlation between arsenic and selenium levels and proximity to natural gas wells. They are uncertain in their conclusions, however, as there are a number of possible causes for their observations. Moreover, they do not link their observations with any communication of "fracking" fluids from depth - if drilling is to blame, they believe is likely to be due to vibrations from drilling operations that agitate old, rusty water wells. This agitation of old rusty metal is the most likely source of the observed metals.  

The majority of water quality studies have found no evidence of fracking-related chemicals in groundwater: some (one from the Duke team, one by Molofsky et al) found no evidence of any effect whatsoever on water quality. One from the Duke team found evidence for methane contamination (see below), but no evidence for "fracking" fluids.

I've also seen videos of a tap catching on fire? Is methane leakage a problem?
Perhaps the most dramatic footage in the famous Gaslands film is the scene where the farmer can set his tap water on fire. This is caused by methane gas contaminating groundwater. Methane itself is not toxic in any way, although if it builds up in large enough quantities it presents a fire hazard.

There are two potential ways that methane trapped at depth in shale rock could get into shallow groundwater - through a pathway in the rock, or through a gas well. As above, if there were an existing pathway through the rock to the surface, then the gas would have already taken that route during the millions of years that it was otherwise trapped. Unlike "fracking" fluids, methane is buoyant and mobile. In drilling a well, a new potential pathway is created for methane to get to the surface.

When wells are drilled, they are lined with several concentric layers of steel, called the casing. When all is as it should be, the gas flows up the middle of the well, inside the casing, to the surface. The casing is fixed into place with a layer of cement that fills the small gap between the casing and the rock.

If there are gaps or cracks in this cement then methane can move up through this gap (sometimes called the annulus) towards the surface. Of course, the crack/gap has to run all the way from the shale layer to the surface. Well bore integrity has long been known as a potential problem for all oil and gas wells, for both conventional and shale reservoirs.

There have been definite examples where poor casing/cement has lead to methane migration into shallow groundwater. Dimock, Pennsylvania, is probably the best-known. The company involved was cited for a number of violations of drilling regulations, and fined heavily. The wells have since been repaired, and methane levels have fallen back to below safe minima. Casing and cement is something the industry has been working with for a long time - there are monitoring tools that can be used to check that there are no gaps or cracks in the cement, and, as at Dimock, it is possible to repair problematic casing.

The majority of methane-in-groundwater complaints come from Pennsylvania. This perhaps inevitable, because methane occurs very commonly in groundwater in PA. There are a number of natural ways that can lead to methane in groundwater. Of course, that means that determining when gas drilling is to blame, and when it is natural, can be problematic.

We know at Dimock the gas was drilling-related. But how common is this problem. There have been three main studies here, two by the Duke team, one by Molofsky et al.. The Duke team studied the Fayetteville shale, Arkansas, and did not find any evidence for drilling-induced methane contamination.

However, when they examined the Marcellus (Pennsylvania), they found evidence for drilling-induced methane contamination. Yet this paper has come in for substantial criticism for two main reasons: the number of samples analysed (only 160ish), and the apparent non-randomness of where the samples were taken from.

To address this, Molofsky et al conducted a much wider sampling regime (over 2,000 samples). They found that if you lived near a gas well, there was a 3 - 4% chance of finding methane in your groundwater. However, if you lived in an area with no drilling, there was also 3-4% chance of finding methane in your groundwater. When you look regionally, whether or not you are in a drilling area doesn't appear to affect the probability of groundwater methane occurrence.

What can we conclude from this? Well integrity and methane leakage is an important issue for the industry, one that it needs to keep on top of. We've seen at Dimock that if a company takes shortcuts, and violates regulations, this can be an issue. Importantly, there are ways to check cement integrity once a well has been drilled, and ways to repair problems.

The question is, how widespread is this issue? The data from Molofsky et al appear to show that it is likely to be a few isolated incidents, rather than a widespread problem. Reviews by the US Groundwater Protection Council have come to a similar conclusion.

I've heard that 5% of wells fail immediately, and that 50% fail eventually?
This is a statistic often cited by opponents of drilling looking to highlight the methane leakage issue discussed above. The statistic comes from a paper by Schlumberger examining wells in the deep Gulf of Mexico, and particularly the chart on page 2. Firstly, it's worth noting that this 'paper' is basically an advert by a company selling well repair solutions, so it's in their interest to 'big-up' the stats as much as possible.

More importantly, what do we mean by 'well failure'? In the context of shale gas extraction, we surely mean that a well that is allowing methane to leak into shallow groundwater. This is where the use of the above statistic is somewhat disingenuous. The statistics in the paper are for sustained casing pressure, or SCP. This is where a portion of the annulus remains pressurised when it shouldn't be. This is absolutely not the same as a well leaking - leaking well will probably experience SCP, but that doesn't mean that SCP indicates a leaking well.

Equally disingenuous is the fact that these stats come from deepwater Gulf of Mexico wells. Drilling is a lot more challenging when there is a couple of kilometers of water between your rig and the ground (as the Deepwater Horizon accident showed). It's only in recent years that drilling technology has advanced to enable us to drill there at all.

It's not a fair comparison to link wells drilled in the GoM with onshore shale wells, the drilling and casing of which is no different to the thousands of conventional onshore wells we've been drilling for almost a century. It'd be like using the number of crashes in an F1 race to predict how many accidents there'll be on the M25. Deepwater GoM wells are at the limits of our technology. Shale gas wells are far more mundane.

If we really want to understand how common well casing issues might be in the UK, surely the best place to look is at our many current onshore wells. There have been over 2,000 wells drilled onshore UK. Whether on not they are "fracked" or not has little bearing on casing integrity. These 2,000 existing onshore wells will be no different to shale gas wells. I'm not aware of any complaints of casing integrity issues or methane contamination from any of these existing sites.

Didn't fracking also trigger an earthquake in Lancashire. Is that common?
It did. In 2011, when Cuadrilla "fracked" a well near Blackpool, two small earthquakes were triggered. Both were very small, at the limits of what humans can feel, and would have caused a similar amount of shaking to an HGV driving past your house.

It's a fact not often appreciated that everything we do in the subsurface carries a small risk of triggering an earthquake, whether it be coal mining, conventional oil/gas, geothermal, hydroelectric. Even quarry blasts are basically man-made earthquakes. Shale gas is no different, there will always be a small risk of triggering small earthquakes. However, this risk is small: only one of the hundreds of thousands of "frack" stages in the US has triggered an earthquake. Any quakes produced will be too small to cause actual damage. DECC have said that every future "fracking" site will require seismic monitoring, and Bristol University have currently deployed seismometers at the Balcombe site (even though they're not planning to "frack" at this stage).

I know that some forms of hydrocarbon extraction lead to subsidence issues. Could that be a problem for shale gas?
When you remove material from the ground, a space is created that is sometimes filled by the overlying material subsiding into the gap. This is particularly true for coal mining, which can cause severe subsidence.

However, shale rocks are dense, with low porosity. That is why they need to be "fracked" to get the gas out. Because of this, they are usually mechanically strong enough to support themselves once the gas is removed. As such, subsidence is not expected to be an issue during shale gas extraction. The Barnett shale in Texas is the oldest shale field: production started over 10 years ago. There has been no measurable subsidence during this time.

How much water will be needed?
Several million gallons of water, or 2 - 5,000 cubic meters of water are needed for each well. That's a couple of olympic-sized swimming pools. That sounds like a lot of water. However, it's important to keep that number in context. The average golf course can easily use this much water a week in summer months. Similarly (and a lot more shockingly), UK water systems leak over 3 billion liters (3 million cubic meters) per day. So if we our utilities were to improve leakage by 1%, we'd have enough water to "frack" 30 stages every day.

In all but the driest places, shale gas development doesn't pose a strain on water resources. Moreover, water abstraction is regulated in the UK. If demands on water resources are too great, the Environment Agency will not provide a license to abstract water, and utilities will not provide it.

What about air pollution, is that a potential issue?
Along with water contamination, this is one of the hot issues for shale extraction, because it involves people's health. There have been a number of regional-scale air quality surveys that do not find any evidence for drilling-related air quality issues, including in the Barnett shale and in Pennsylvania. In fact, the Pennsylvania report shows significant improvements in air quality, mainly because coal-fired power stations are being replace by gas power stations.

More localised studies have found the occasional issue, mainly it seems with compressor stations rather than drilling sites. However, even these studies have concluded that "the screening results do not indicate a potential for major air-related health issues associated with the Marcellus Shale drilling activities".

Fracking might be ok in the wide-open spaces of the US, but surely there's no space for it in the UK?
It's true that shale gas extraction is easier in unpopulated areas. Opponents of shale gas often show images of the Jonah gas field, where the land is covered with wells. This is actually a conventional gas field, drilled in the 1990s, before horizontal drilling had taken off. The benefit of horizontal drilling is that you don't need nearly as many well pads.

The truth is that the drilling industry is very adaptable. Sure, if you give them a big empty space and tell them you can drill all over it, then they probably will. However, they can cope in far more constrained conditions when it is necessary. Perhaps the best example of this is Dallas-Forth Worth. This is the 9th most populated city in America, with a population of over 6 million. Yet the Barnett shale runs right underneath, and it's being drilled. By using long lateral wells, drilling sites can be squeezed into urban and suburban areas without taking up much space at all.

Does the UK have much of a record for onshore drilling?
The UK onshore industry does not have a very visible profile. However, it is there: we produce 100 million cubic meters of gas per year. Over 2,000 onshore wells have been drilled in the UK. Of these, about 200 have been "fracked". I've plotted a map of all the wells here. In some places, such as Beckingham Marshes, they manage to squeeze a lot of wells into not-very-much space, without upsetting local people.

The UK onshore industry has been very good at staying out of sight, and very good at making sure they do not pollute. If we want to predict what shale gas development in the UK will be like, the first place to look should be the current onshore industry, which does a very effective job working with local communities.

I've heard that the methane leaks mean that shale gas is actually worse for climate change than coal. Is that true?
Burning coal for electricity produces approximately 3 times as much CO2 as natural gas does. Therefore, switching from coal fired to natural gas fired electricity should represent a significant benefit. CO2 emissions in the US have dropped significantly as gas has replaced coal as a source of electricity.

However, natural gas production has the potential to release methane to the atmosphere. Methane is also a potent greenhouse gas, so if shale gas extraction emits a lot of methane, it could counteract the benefits of reduced CO2. This was the premise of a paper by Howarth et al., which has garnered a lot of publicity. However, this paper has come in for a raft of criticism, as most other studies on the subject have indicated very clear benefits from switching from coal to gas. No Hot Air lists some of the scathing comments about the Howarth paper.

A study funded by the EU Commission concluded that, with respect to greenhouse gas emission, domestic shale gas production has a similar footprint to imported gas (that has to be compressed and shipped to Europe from the Middle East), and a significantly better footprint than coal. 


Even if it's better than coal, gas is still a fossil fuel. Surely we should be focusing all our efforts on renewable electricity?  
Now we're on to a more serious criticism of shale gas development. We know we already have more fossil fuel reserves than we can safely burn without causing catastrophic climate change, so why are we bothering to look for more?

My answer to this comes in two parts: firstly is to point out, as above, that for a unit of energy produced, shale gas emits less than half as much CO2 as coal. If we are to avoid climate change, there must presumably be an upper limit to the rate that we can emit CO2. If the treat of climate change requires us to ration our CO2 emissions, it seems obvious that we should choose the fuel source that gives us the most energy for that ration of CO2 emission. That fuel source, by a significant margin, is gas.

It's correct that we should leave a large portion of our current fossil fuel reserves in the ground. That portion, however, should be coal. Moreover, renewable energy currently requires flexible backup sources - an abundance of gas provides this.

My second argument relates to how we get to a point where our CO2 emissions are reduced. A common call is that 'we should be investing in renewable energy sources'. This is absolutely true. However, in order to invest, you need to have money to invest. Given our current economic struggles, it becomes harder and harder to politically justify renewable energy receiving public money, either as a supplement on bills or as a direct subsidy from the treasury.

If the economy improves, there will be more money available to invest. In my opinion, we should be ring-fencing a proportion of the taxes made on shale gas development, in order that they be re-invested into renewables and/or next-gen nuclear. This would ensure that in the short term we reduce our CO2 emissions by replacing coal fired power, but that in the long term investment continues in alternative energy sources, such that they will be ready as soon as possible.

That's the theory, how does this bear up to reality? Well, Texas is the undisputed home of shale gas, with the Barnett, Eagleford and Haynesville shale plays. Yet, perhaps surprisingly, Texas is also one of the leading states in terms of renewable energy, and the renewables boom has occurred at pretty-much the same time as the shale boom. In Texas, at least, a booming shale gas industry has gone hand-in-hand with booming renewables, rather than competing with each other.

Will shale gas have an impact on my gas bills? 
This is somewhat uncertain, and as a geoscientist I'm probably straying outside of my main area of expertise. The most recent report commissioned by the government suggests prices could fall by 25%. However, other reports have suggested it would have less of an impact.

However, it's important to look at the economic impacts beyond consumer gas prices. At present, we expect to be buying more and more gas from places like Norway and Qatar. That is money that leaves the UK economy for good, never to be seen again. It creates no jobs, and pays no taxes.

In contrast, a UK shale gas industry would provide jobs for UK workers. It's true that some of those jobs would be specialists, attracting high-payed international workers. That is still beneficial to the UK economy, because those people will live in the UK, and spend their money here. But there are many lower-skilled jobs involved as well.

Moreover, remember the manufacturing chain. For example, well pads need cement. The casing is high quality steel, and each well needs several kilometers of it. That means work for people who make cement and steel. Add in the mulitplier effect, as more employment means more people buying things in shops, eating in restaurants, staying in hotels, and it's clear that, whatever the effect on the gas price, shale development will have a significant impact on the economy.

Equally, any gas produced will be taxed. That's money going into the public purse, to be spent on schools, hospitals, or even wind farms. Public finances appear to be somewhat short of cash at the moment. Given our current situation, I don't think we can afford to be handing billions of pounds a year over to Qatar to host an air-conditioned World Cup when we could be reaping the economic benefits of shale gas development at home.  


 

Greenpeace BS

I've commented before about Frack-Off's spectacular hypocrisy, and a recent video that really brings out the science around shale gas development.

In this post, here's Greenpeace using bullshit in lieu of actually managing to get a story. This actually came out a little while ago, but it was just before Iain Stewart's Horizon documentary, and then events in Balcombe, which have somewhat dominated most of my "social media time".

In a post from Lawrence Carter of Greenpeace, who reckons he has some sort of scoop, trapping a Cuadrilla executive on tape "admitting that everything he says in public is bullshit". You can listen to the recording here, and, as always, judge for yourself.

Funnily enough, the tape cuts just after the "bullshit", although you can just about hear the "but" that comes afterwards. I've asked Lawrence for the rest of the tape (and I'm not the only one to do so), strangely enough it has not been forthcoming. Perhaps the tape just happened to conk out just at that point. Or maybe he goes on to say something along the lines of, as Nick Grealy suggests: "everything I say sounds like utter f***ing bullshit, but it's the real deal". Or as I imagine it might be: "everything I say sounds like utter f***ing bullshit, but it's actually backed up by peer reviewed science".

According to Lawrence, it "was something about renewables and shale gas living hand in hand, aka bullshit". I'm not sure how that ranks as bullshit, given the generally agreed consensus that large-scale renewable grid penetration requires quickly-dispatch-able gas power plants as back-up - read here for a recent report from Citi-Group on the issue, for example. This is borne out in real life too, as well as in studies: renewable energy has boomed in the USA the same time as the shale gas revolution. Texas is the undoubted 'home' of shale gas, yet renewable energy has grown significantly over the same time period.

Greenpeace have an annual turnover of over £200 million. That makes them a lot larger than the likes of Cuadrilla. I think that they have a certain responsibility to act in good faith as they pursue their agenda - bullshit like this simply does not cut it.

A message from the Balcombe front lines

I'm sure that if you're reading this blog, you're aware of the current protest ongoing in the village of Balcombe. The main impact for me has been a lot of radio interview requests, but also, if the Blogger stats page is to be believed, a surge of interest in this blog. For obvious reasons, the protest itself has had as much of an impact on the local community as the drilling itself. Reports from either side of the debate will tell you either that the locals are fed up to the back teeth of the imported rent-a-mob, or that the locals are joining in with gusto.

If you'll excuse me another colossal name-drop, chatting to Prof Iain Stewart after his visit to Pennsylvania for his Horizon documentary, one of the most striking impacts that he found wasn't the pollution or lack of it, but how drilling had divided communities. Sadly, it seems that this is already happening in Balcombe, as a message I received from a local resident will testify:

A few months ago, I like many had never heard of fracking! Just a few lines to put you in the picture about who I am. Malcolm Thomason is my name, a 56 year old Balcombe born & bred guy. Until a couple of weeks ago most in the world had never heard of our lovely village with a population of about 1750. Balcombe is about 16 miles due north of Brighton, 8 miles south of Gatwick Airport in the Sussex Weald. We have a lake, mill and the fantastic Ardingly Reservoir - most of reservoir is in Balcombe. We have a pub, social club and a village shop. Not a lot but its nice and mainly quiet. But in recent years the outsiders, not village types have moved here, paying vast prices for houses near the main London-Brighton rail line with easy access to Croydon & London. I would say 25/30 years ago I knew 90% of the Village and now I dont know 90%. Thats the short introduction done with !

In 1986 Conoco drilled the same site next to B2036 south of village for 23 days. The site is 600-700yds due south of my house as crow flies. In 1986 there were no protesters, in fact we were invited to view site and to see what was going on, a very interesting visit it was as well. Conoco found some oil, not in large quantities but it was there.

How things have changed in July/Aug 2013, we have now been invaded by a vast array of people of all descriptions. Another 1000 NoDashForGas folk are setting up a camp in a field from 16-21August, the same group that shut down West Burton power station for three days last year! They seem intent on shutting down also the Cuadrilla site in Balcombe as well.

Not knowing about fracking I set of to research the subject! Plenty info about if one cares to take time and look that shows in my opinion that it is not dangerous in any shape or form! Just scaremongers putting out propaganda to try and convince the gullible that its not the thing to do! I stumbled across James Verdon twitter page and read with interest his blogs on fracking and learnt a lot more than I already knew. I only wish the antis in Balcombe would view these blogs, but a lot can only see the the water being polluted, the fantastic Victorian Balcombe Viaduct finished in 1841 collapsing through an earthquake, and the blue skies turning black!

This issue is already dividing a village with people who used to talk to each other, now trying to avoid each other, a sad state of affairs i think you all will agree!

Guardian given lifelong ban on talking sense

In the latest Guardian shale shock story, a shale gas company in Pennsylvania (Range Resources) stands accused of poisoning a family's water (the Hallowiches), then imposing a court gagging order to silence the family, including the children, from ever talking publicly about fracking ever again.

In actual fact, this story has been 'out' in the US for quite some time, so it's hardly the scoop that the Guardian are claiming. More importantly, however, are the numerous facts left out in the name of a good scare story.

Court gagging orders are never going to make for good PR, but the key question must be: did Range Resources actually cause contamination of the Hallowich water supplies or air quality? Everything else is just lawyers throwing their weight around.

Pennsylvania DEP conducted an investigation into the Hallowich groundwater, and their findings are available. Here are their conclusions, which I shall selectively quote from below:

you allege that Range Resources has contaminated the supply [...] After a review of the information, including primarily water analyses, we cannot affirm your conclusions.

Importantly, Range actually drilled their well in July 2007. The Hallowiches only purchased the property in June 2007, and didn't drill their water well until October 2007, 3 months after the shale well was drilled. Therefore they can have no evidence regarding water quality prior to shale drilling.

Acrylonitrile and styrene appear to have been identified as an offending chemicals. However,

RT’s [a water testing lab] own sampling did not measure any styrene at the reported detection level. How styrene might be related to gas well drilling is not clear. However, the water lines in the Hallowich household, as well as from the water well to the house, are PVC which contains styrene.

and

Acrylonitrile is used in the manufacture of plastics, glues, pesticides, ABS pipe (common drain line pipe used in homes; the “A” in ABS stands for acrylonitrile ), synthetic rubber, acrylics, carpets, dinnerware, food containers, toys, luggage, automotive parts, appliance, telephones, among others. It can also be washed from the air by rain and then enter the groundwater system. There is a plastic rock which has been placed over the water well and could be leaching contaminants into the ground during rainfall events, which interestingly enough is when Mrs. Hallowich reports that the acrylonitrile values seem to increase based upon on-going sampling that apparently has been occurring.

This might be why, in the absence of any data prior to drilling, the DEP tested water from nearby wells close to the shale drilling, and did not find acrylonitrile or styrene:

the results taken at a neighboring property (163 Avella Road), which is also close to the gas well, only shows a lead problem; the other four parameters are either non-detect or within drinking water standards. 

In conclusion, the DEP summarise:

Mrs. Hallowich alleges that the drilling of the gas well polluted the aquifer. [...] we are lacking any direct evidence to prove this assertion.

we question your conclusions about the contamination problems to the Hallowich water supply. The only parameter that is clearly above the MCL is manganese, and we cannot clearly link it to the drilling of the Range Resources gas well. Therefore the DEP cannot issue a water supply replacement/restoration order to Range Resources.

This area also formed part of a DEP study into air quality impacts of Marcellus drilling, similarly finding that

the screening results found during the five-week study did not indicate a potential for major air-related health issues associated with the Marcellus Shale natural gas activities

Given the above data, it is perhaps not surprising to find that, in the court documents, the Hallowiches concede that:

1. With respect to Plaintiff minors’ alleged claims involve nuisance and personal injury claims, there is presently no medical evidence that these symptoms are definitively related to any exposure to the activities of Defendants...

2. The minors have alleged claims for nuisance and personal injury in connection with Defendants’ business operations.  There is presently no medical evidence supporting that these claims related to any exposure to Defendants’ business operations as set forth in Plaintiffs’ Complaint.

When the court order to 'un-gag' these documents were made, there was much excitement in the media in the hope that a smoking gun was about to be revealed. Much has been made about such gagging orders: surely now the release of one such set of documents would catch the frackers red-handed. Instead, they found instead that once again, water and air testing by the relevant government agencies had failed to find evidence of fracking-induced contamination:

There's no doubt that gagging clauses make for bad PR. However, this case shows that just because they have been used, doesn't mean that there is evidence for shale gas pollution. In fact, as the Pittsburgh-Tribune has the headline, it might be better to describe the situation as: Couple collect $750K settlement in fracking case with no medical evidence.

The information I've presented above is easily-locatable in the public domain. Which begs the question - why does none of it make it into the Guardian's latest scare story? I think we're all fine with media organisations that take a well established editorial line - it's unlikely the Guardian are ever going to favour shale gas extraction. However, I'm a lot less happy with irresponsible scare-mongering, which is what I see this to be.

Update: Map of existing UK oil and gas wells

In a previous post I discussed the 2000 or so pre-existing onshore oil and gas wells in the UK that rarely seem to get a mention when people talk about shale gas extraction despoiling our wonderful countryside. Well, in a quiet moment at work I made a map showing where they are (click to enlarge). Each red pin is an oil or gas well drilled between 1902 to the present day.

Update: I have modified the map to colour-code the wells by the date they were drillied. Pre-1949 are cyan, 1950 - 1979 are yellow, 1980 - 1999 are (light) pink, and 2000 - 2013 are (dark) purple. 

Update 2: You can download the original data from the DECC website at: 
https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/224856/Landwells22July2013.xlsx. Lat/long data is in Deg/Min/Sec.

I created .kml files to plot the data in Google earth. You can download the 4 files at:
http://www1.gly.bris.ac.uk/~JamesVerdon/Downloads/uk_wells_1900-1949.kml
http://www1.gly.bris.ac.uk/~JamesVerdon/Downloads/uk_wells_1950-1979.kml
http://www1.gly.bris.ac.uk/~JamesVerdon/Downloads/uk_wells_1950-1999.kml
http://www1.gly.bris.ac.uk/~JamesVerdon/Downloads/uk_wells_2000-present.kml

 

Radio 4 You and Yours Interview

On the radio again, this time Radio 4 (does this count as a promotion from 5Live?):

Talking about Balcombe on 5Live, and is the UK oil industry a victim of its own success?

With the protest ongoing outside Cuadrilla's drill site near Balcombe, it's somewhat inevitable that I'd end up on the radio again - 5Live Drive once again. I've included the whole segment, including Bianca Jagger, a man from Blackpool who finds the whole shale gas thing a little boring, Vanessa Vine from Frack-Free-Sussex who finds the whole thing very exciting, and finally I get squeezed in at the end.

Beyond giving you the chance to enjoy my honey-ed tones once more, there are a couple of points that arose from this interview that I'd like to expand on.

The first thing that came to mind while listening to the anti-fracking interviewee was the issue of geological dread in public perception of risk. The concept of 'dread' in public risk perception is well established. From Wikipedia, a dread risk elicits visceral feeling of terror, uncontrollable, and catastrophe. It was coined in an attempt to understand why public perception of risk is often very different to expert assessment of risk. It is often that sense of an unknown danger that provokes feelings of dread. It was initially used to describe feelings towards nuclear power, but I think it applies equally to things like flying (for some people), but especially GM food, and now fracking.

Quoting the interviewee, fracking is 'messing with subterranean geology', and 'we cannot legislate for the vagaries of subterranean geology, it's such a human arrogance'. It seems that the public has this idea that the subsurface is unknowable and uncontrollable, leading to feelings of dread. I would argue that while the subsurface can no doubt be a challenging environment, there are hundreds of thousands, if not millions of people, geologists/geophysicists/hydrologists/geochemists etc., for whom understanding and making use of the subsurface is the bread and butter of their day to day life.

Geologists (Iain Stewart aside, perhaps) don't talk enough to the general public. We saw this in the furore over Iain Duncan Smith's comments about shelf-stackers being more important than geologists, where geologists finally had the gumption to point out to the rest of the world how important they actually are. And we are incredibly important.

Take a look at all the objects around you and in your life. If it's not made of animal (wool, leather) or plant (wood, cotton) then chances are it's made of something extracted from this apparently unknowable subterranean geology, that apparently we shouldn't be messing with.

It might be stone, which has to be quarried, cement and concrete products made from quarried aggregates and limestone. If it's plastic or synthetic then it's made from oil. If it's metal then that metal had to be mined somewhere. Moreover, all of the energy we use involves the subsurface as well. Hydrocarbons are the most obvious example. But where does the uranium come from that we put in our nuclear power plants? What about renewable sources, surely these will take us away from that dreadful subterranean geology with which thou shalt not mess? Well, a typical wind turbine needs something close to 100kg of neodymium, which can only be found in a few places, and mining it is not exactly a pleasant process. And hydroelectric? Well, it's well established that reservoir impoundment for hydroelectric can produce large earthquakes - for example the 2008 magnitude 7.9 Sichuan earthquake, which killed 80,000 people, has been linked with the impoundment of the Zipingpu Dam. Slightly more dramatic than the Blackpool tremor I feel.

Much of human endeavor has been based on 'messing with subterranean geology'. During fracking, we can use geophysical methods to monitor exactly where the induced fractures have gone, and to ensure that they are wholly contained within the targeted shale beds. As geologists, we have to accept that the public are unlikely to fully understand what we do. However, shale gas extraction is not an uncontrolled, poorly understood process. To claim that it is is to do insult to the thousands, or millions, of geologists around the world who do this kind of thing, successfully, every day.

Speaking of success, the events in Balcombe raise a second point. I am wondering whether the current UK onshore oil and gas activities have been a victim of their own success in hiding their operations from the public for the last 50 years.

Protestors talk about thousands of well sites despoiling our beautiful countryside. Which is strange, because we already have thousands of onshore wells across our countryside. Literally, 2000 wells - you can download a spreadsheet listing them all here. 10% of these, so about 200, have been hydraulically stimulated. Yet no-one seems to even know that they are there, and certainly no-one seems to be claiming that 50% of them are leaking hydrocarbons and/or carcinogens to contaminate groundwater.

Our onshore industry has been very effective at (a) making sure that they don't cause environmental problems and (b) doing everything that they can to stay out of the public view. I grew up a few miles down the road from the Humbly Grove Field, which is here (as per my Fort Worth post, go to StreetView and see if you can even see it), yet until I went to university I didn't even know it was there.

Now, when a new well is proposed, because people don't know anything about the onshore industry, the thought of drilling in the rural UK countryside seems crazy, (indeed it even induces dread), even though there are 2000 wells already there.

It's understandable that when we seek to understand shale gas impacts we look to the US, and we try to understand the issues they have faced, and what the development has ended up looking like. However, we should also look to our own industry. If we want to know whether it is possible to conceal well pads without despoiling the countryside, we should look at our own ability to do so, not what American regulators and planning rules allow. If we want to know whether wells are likely to leak, we should look at whether our own 2,000 wells are leaking, not whether wells drilled under American regulatory and inspection regimes are leaking.

There's one major aspect of the media attention at Balcombe that has surprised me. There is ALREADY an oil well on the Balcombe site, drilled in the 1980s by Conoco. They abandoned it because the price of oil dropped to $10 per barrel, while now it is over $100. I've not seen this well mentioned in many reports from Balcombe. Has the old well has been causing problems for Balcombe for the last 25 years? I doubt it. I would love to know what it is about the new well that people see problems? Why will it be different, or more likely to cause problems, than the one that is already there? 

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.