Saturday 17 December 2011

Earthquakes near Blackpool

So, we've established that fracking won't cause volcanoes. But what about earthquakes? It's well known now that fracking activities appear to have produced two earthquakes at the Cuadrilla site near Blackpool. These earthquakes - in April and May 2011 - had magnitudes of 1.7 and 2.5. Earthquakes of this size have never been experienced during fracking before, so it's really interesting to have a look at them.

Firstly, how do their magnitudes correspond to what has gone before, and what earthquakes are like in nature. All fracking produces 'microearthquakes' - these are just like earthquakes except, as you'd guess from the name, much smaller. Typical earthquakes during fracking have magnitudes of -3 to 0. These are too small to be felt at the surface, even by a seismogram. However, geophysicists like myself will place geophones down boreholes near to the fracture stimulation to detect these microearthquakes, and use their locations to map the course of the fracture as it propagates out from the well. Earthquake magnitudes are on a logarithmic scale, so a magnitude -3 event releases 10^11 Dcm (that's dyne-cm, don't ask) of energy. A mag 0 releases 10^16 Dcm, so that's 10^5, or 100000 times larger. A mag 3 event releases 10^20 Dcm, so 10000 times larger than the largest event seen during fracking so far.

Why did this event happen then? Well, the official report claims that a critically stressed fault, near to the fracking site, was reactivated. As the fluid from the frack impinges on the fault, it increases the pore pressure, reducing effective normal stress and triggering failure. Seems plausible enough to me. A pre-existing fault is pretty much required to get a mag 3 quake. If the fault was close to critical stress, it implies this earthquake would have happened soon anyway - the fracking didn't produce a new earthquake, it just hurried it along.

A magnitude 3 earthquake is classed and 'small', and not damaging. If we lived somewhere like California or Japan, a mag 3 wouldn't even be noticed. It once you get up to mag 5 or 6, 1000s of times larger again than a mag 3, that people need to start really worrying. We have about 1 or 2 mag 3 events occurring naturally in this country every year. It'd feel something like a large truck going past your house at speed, rattling the window frames and such, but no damage caused.

So what does this mean going forward? Is a mag 3 quake worth stopping fracking and shale gas exploration for? Unfortunately, this is where scientists provide the facts (see above) and then hand over to the policy makers. The current system put in place by Cuadrilla is that if they trigger anything above a mag 1.7 they'll stop fracking and drain down the pressures. So it remains to be seen if they'll trigger more earthquakes in future wells. The report seems pretty confident that they won't, but then they would say that wouldn't they. They say it's an unfortunate accident of unique geology. However, the Bowland shale is pretty deformed and faulted, so it'll be really interesting to see if they can miss all the faults in the future.

Friday 16 December 2011

Letter to the Editor.....

The recent reports about fracking producing a volcano in the Mendips riled me enough to write an angry letter to the Wells Journal and Bath Chronicle. Still waiting to hear if either will publish it.

Dear Editors,

I am writing to express my concern at reports suggesting that shale gas exploitation could trigger a volcano in the Mendips (More concern over fracking, Bath Chronicle, Thurs 1st December; 'We could be sitting on a Mendip volcano' says Somerset expert, Wells Journal, Sat 3rd December). Such alarmist scare stories, with no factual basis whatsoever, will not help to promote a constructive discussion about shale gas exploitation as hydraulic fracturing develops in the UK.

Let us be clear, there is no 'river of lava ready to erupt' below the Mendips, no 'sleeping giant' to be awakened. The volcanic deposits in the Mendips were formed during the Silurian Period, approximately 425 million years ago. At this time, Britain was located 20 degrees south of the Equator, as the continental plates of Avalonia, Baltica and Laurentia collided to form an Alpine-scale orogeny. These volcanos ceased to be active, and rocks ceased to be molten, some 400 million years ago. All that remains are the solidified volcanic rocks, which contain a little residual warmth that heats the warm springs. Such deposits are common across much of the UK, in the Lake District, North Wales, and Western Scotland, for example.

There is a genuine discussion that needs to take place regarding shale gas and fracking. Potential issues include increases in heavy vehicular traffic moving equipment to the drill pads; the presence of 5 acre drill-pads, in place for perhaps 6-8 months or more in an area of natural beauty; the significant volumes of water required for fracking (usually measured in millions of gallons); and the ability of treatment facilities to handle and treat this water after fracking has been completed.

This discussion needs to be based on facts, logic and reason, weighing the potential economic benefits (particularly relevant in this time of austerity and high unemployment) against potential negative effects. Misleading scare stories about volcanic 'sleeping giants', or the videos of flammable tap-water that existed long before fracking began, are not productive. Besides slanting the discussion against shale gas exploration in an unfair manner, these reports in fact do a disservice to those who oppose shale gas on more reasonable grounds, as the temptation is then to lump all 'anti-frackers' together as unscientific, uninformed scare-mongers with no interest in evidence and no understanding of simple geological principles.

It is particularly concerning that this report comes from a Mendips District Councillor. One expects a certain degree on local knowledge from local councillors. However, despite his concerns about volcanic activity, Cllr Taylor seems totally unaware of the presence of one of the world's leading volcanology research groups (led by Prof Steve Sparks FRS CBE) just up the road at Bristol
University. I have had the pleasure of meeting Cllr Taylor during filming of the recent BBC Inside Out West report on fracking, and I have made the above points to him. However, the councillor appears to be less interested in gathering evidence than he is in promulgating baseless scare stories. The Mendips deserve better from their councillors.

I am not an advocate for the fracking industry. However, as a scientist I am concerned that, whatever the decisions made by Somerset Council (and at higher levels) on shale gas development, they should come from a careful assesment of the potential benefits and issues, based on evidence and reason. Unsubstantiated reports about 'rivers of lava' and 'sleeping giants' are of no help to this decision-making process, and it is of particular concern when these stories emerge from those elected to lead us.

Yours Faithfully,

Disgusted from Tunbridge Wells, etc etc

Sunday 4 December 2011

Could fracking cause a volcano?

Could hydraulic fracturing and shale gas extraction awaken a dormant volcano in the Mendips?

'We could be sitting on a Mendip volcano' says Somerset expert

Well, could it?

No. Not even remotely. The Moon's Hill quarry may well be the site of a Silurian volcano. However, the Silurian was 430 million years ago. At this period in geologic time, Britain was sitting somewhere near the equator, during a collision between two continental plates (Laurentia and Baltica), forming an Alpine-scale mountain building event. This 'volcano' has not been active for hundreds of millions of years. There are no longer two large continental plates crashing together (the kind of thing needed to get large volcanoes and earthquakes, see 'Pacific ring of fire'). There is no molten magma sitting just beneath the Mendips, ready to erupt. It would have cooled off 400 million years ago. There's just some slightly warm rocks capable of warming rainwater a little. Much like under large parts of the rest of the UK.

But what really grates me about this article is that I had a long chat Councillor Nigel Taylor while filming for a recent BBC Inside Out West special on fracking (go to about 11 minutes in). He put this concern to me (it didn't make the final cut for the IOW report), and I had a good long chat about what it means when a geologist talks about volcanic deposits from the Silurian, and that it doesn't mean there's still a volcano waiting to erupt just below the surface.

So it would appear that Cllr Taylor has chosen not to listen to clear science from a geologist, and has instead chosen to make himself appear to be a bit of berk (to anyone who understands geology at any rate). During our conversation, he appear to accept that he was wrong to be concerned about a volcano in the Mendips.

This is a disappointment, because this warning (and remember the headline claims this to have come from an 'expert') is no doubt making its way around the interweb as we speak, to be brought up at the next fracking protest. There are genuine reasons for concern about hydraulic fracking. If, however, rather than talking about the genuine issues, using facts, logic and science as our basis, we are instead talking about creating volcanoes, then everyone is wasting their time.

Nigel Taylor, you are deliberately and knowingly spreading misinformation about fracking. The Mendip district deserves better from their councillors. Regardless of the decision at which Somerset council arrives regarding fracking, please let it be based on fact, science and evidence. When scientific experts are available to you, please listen to them, don't play along and then ignore them.

Final rant, now aimed at 'This is Somerset': why do you name Cllr Taylor as an 'expert'? An expert on what? Not geology or volcanology, that's for sure. An expert on Somerset I guess would be the most literal interpretation, and perhaps he is. But then, if we're going to be talking about setting off volcanoes, surely the expert in question should be a volcanologist. And it's not like they're hard to find - just up the road in Bristol you could have found for example, Steve Sparks, one of the most pre-eminent volcanologists in the world. Had you wanted a little balance in your article.....

Saturday 8 October 2011

Careering out of control

Another re-post I'm afraid (I promise a proper new post will appear soon...) - whether you're in favour or against fracking, wouldn't it be great if we could ensure that there were plenty of scientists around to evaluate the risks and benefits. That would of course mean that we need to sort out the careers structure available for young scientists in this country: 

For the record, I'm currently starting a 3 year position as a research fellow. I was pretty fortunate to get this position, success rates for applicants is something like 10-15%. At the end of 3 years, I'll have to re-apply for a new position. I'll almost certainly have to move to a new university. And if I'm not successful, I'll have nothing to fall back on but the dole queue. Which would seem like a waste of 8 years of undergraduate, masters and PhD training. I know many of my colleagues who are in similar situations - coming to the end of their PhDs and unable to find postdoc positions, or scrabbling about for 3 months of funding at £11 an hour (typically given to summer interns, but I know people who are in fairly desperate straits and will take anything to keep them going for a few more months, giving themselves a bit more time to find a proper postdoc position).

So it'd be nice if we encouraged young people with PhDs to take up a career in science, rather than subjecting them to a string of short-term contracts with zero job security, few opportunities of permanent positions, and a requirement to constantly move across the country for each position: It's pretty much an unwritten rule that, as a young scientist, you won't get funding for a postdoc position if you stay in the same place for more than about 3 years.

I suppose I can't really complain: I did choose this career path after all, and if job security and higher pay were my main objectives, I could have been working for Shell or BP for 6 years or so by now. But the fracking issue highlights the importance of scientists to keep our increasingly technological society functioning. Fracking in particular highlights the need to have scientists around who aren't funded by industry, and therefore can give a more impartial view......

It'd be nice if our career structure reflected this. Just sayin' is all......

Friday 30 September 2011

Plastic spoons.....

A quick repost (perhaps if I was a twitterer, it'd be more appropriate for the shorter format), but perhaps this sums up why we need shale gas in the first place:

Monday 26 September 2011

Monitoring a Frack Job...

Ever want to know what frack job looks like? Here's a video:

What is this video showing, I hear you ask? This is a plot of all the microseismic events occurring during a frack-job. As the fluids are pumped in, the rock begins to break and fracture. The fracturing releases seismic energy. In many ways this process can be considered analagous to earthquakes, except they are many orders of magnitude smaller. Hence they are referred to as microseismic events.

Geophysicists place geophones in the ground near to the region of interest. These geophones detect the P and S-waves produced by the microseismic events, allowing us to compute their locations. We use their locations to create a picture, showing where the fractures have gone during the frack job.

This video is a map view of event locations. The injection point is at (0,0). The events track the formation of a fracture zone approximately 300m long, with a strike of 080 degrees, over the course of the frack job (in 3 stages, over 10 hours in total, from 7 in the morning to 5 in the afternoon).

Acknowledgements for this video to Andreas Wuestefeld, my colleague at Bristol University.

If you want to ask a question about this video, do post a quick comment.

Saturday 24 September 2011

Why shale gas reservoirs need to be fracked

Seeing as I'm on a roll today (it's a cloudy Saturday, and I'm a little hungover with no current desire to do anything but lie on the sofa and mess about on t'internet) I thought I'd add one last post that might help explain why we need fracking to extract gas from shale formations (this will also give me a chance to test out how blogger handles images). This comes from a simulation I use to teach undergraduates at Bristol about fracking and shale gas.

In the first example, we try to extract gas from a shale reservoir with 5 vertical wells, and no fracturing. The low permeability means that gas is only extracted from the regions immediately adjacent to the wells. The resulting gas production rates are plotted - a paltry 3000m3/day.

The second example shows what happens if the wells have been fracked. A high permeability zone (in green) now extends from each well. This means that we can now access the gas from a much higher proportion of the reservoir, as it flows into the fractures and then into the wells. Now, the gas production rate hits a peak of 500,000m3/day during the first year, before tailing off to a rate of 50 - 100,000 m3/day. Much more gas, much more money. All hail fracking!

Or so it would seem. However, this simulation also highlights a possible issue with shale gas and fracking. After the first year or so, production often tails off dramatically, meaning that new wells must be drilled, and new fracking operations carried out, almost constantly to keep extracting the gas. It's not like some conventional field where you drill a well, and then it keeps producing for the next 20 years. Good news for drilling engineers and geologists who'll be kept in a job, but it makes extraction more expensive, and the more you frack, the greater the potential for things to go wrong.

Note of acknowledgement - this reservoir simulation was creating using 'Tempest', which is developed by Roxar Ltd.

A little about myself

Having welcomed you to my sparkly new blog, I feel I should introduce myself properly. I am a research fellow at the University of Bristol. Given the current vogue in academia for multi-disciplinarity, I suppose I would describe myself as an applied geophysicist-cum-geomechanical engineer. Which, in short, means that I'm interested in rocks. In particular, I'm interested in the mechanical behaviour of rocks - how they deform, break and fracture - and also in how we go about monitoring this behaviour (which is a challenge, given that you're often separated from the rocks you're interested in by a couple of solid kilometers of other rocks).

Given the highly politicised nature of the debate about fracking, I feel I should make some statements about any conflicts of interest. The funding for my research comes from the UK government science research councils (NERC, to be precise). Nevertheless, we work fairly closely with industry - they often give us datasets from past fracking operations for us to look at. We're interested in developing techniques that will allow us better control over where the fractures go, and techniques that will allow us to image then fractures - as are the companies conducting the fracking, so we have a lot of common ground. There are other people in our research group who are funded directly with money from industry, and indeed, several of my ex-colleagues (and an M.Sci student I co-supervised) have gone on to jobs in the shale-gas industry.

But I would not consider myself to be an industry stooge. I suppose I would describe my views as being mildly pro-fracking, but only when done properly. I believe it is possible to frack without damaging the local environment, but only if done responsibly. There are many temptations to cut corners, and I suspect this is what has sometimes happened in the US. Many shale gas wells are pretty marginal economically, so there must be pressure to take short-cuts in monitoring and controlling the frack, and in disposing of the waste materials properly. I'd very much like to avoid that happening in Lancashire.

So, truth be told, my views on fracking are still developing. In particular, while I'd like to think that I know a fair bit (so modest) about the mechanical behaviour of rocks during the fracking process, I don't think I've thought enough about the wider social, political, economic and environmental (both local groundwater, and in terms of climate change) issues of shale gas exploitation. I suppose this blog is a way of addressing that - by forcing myself to write about it I'll force myself to think about it a little more. So I guess I might as well be talking to myself.....

So if seems like I contradict myself, or if appear to change my views on shale gas, then that's because I'm holding contradictory views, or I'm changing my mind. I'm a scientist, and all good scientists reserve the right to change their mind when the prevailing evidence dictates.

Friday 23 September 2011

Welcome to Frack-Land

So it begins......

If you haven't heard the news, after some exploratory drilling, Cuadrilla reckon that the shale gas reserves underneath Lancashire amount to approximately 200 trillion cubic feet. That's a lot of gas! Enough to fill 2 billion Olympic swimming pools (and x billion double decker buses and to cover y Waleses to a depth of z meters, etc etc etc). Put another way, and perhaps more importantly, at a price of $7 per 1000cbf (2007 prices, I don't have current prices to hand), that's $1.4 trillion dollars-worth of gas. Check out news articles here and here, for instance, or just about any other newspaper of your choice.

So what's this gas doing here? By which I mean - why didn't we drill and extract all of this gas at the same time as we were exploiting and developing the now-nearly-depleted North Sea reserves, back in the 70s and 80s? The reason is that under Lancashire the gas is trapped in shale rocks, rather than the sandstones that all oil industry geologists like. Because shales are made of tiny mud and clay particles, rather than nice round sand grains, they have very low permeability, making the process of sucking the gas through the rock to the well bore very challenging. Imagine trying to suck your drink through a straw filled with mud. Up until a few years ago, we couldn't do it.

However, a new technology has recently been developed to access this previously unexploitable gas. After a well is drilled, fluids (usually water, but sometimes CO2 or nitrogen gas) are pumped down and into the reservoir at high pressure. The effect of these high pressure fluids is to overcome the strength of the rock, causing it to fracture. The fractures in the rock provide corridors down which the gas can flow to get from the rocks to the well (and then eventually to our boilers and power stations).

The most likely reason you've found this blog is that you're already interested in fracking, (let's face it, it won't be for the humour, or Shakespearian-quality prose...) so you'll already be aware that this fracking process is controversial to say the least. There's the possibility of groundwater contamination from the chemical additives in the fracking fluid, there's the possibility of water contamination from methane rising from the reservoirs (cf. all the infamous flammable taps videos you'll find on youtube). And of course, there are those who feel, given that we already have enough fossil fuels at our disposable in known reserves to leave our planet considerabley warmer than nature intended, that we shouldn't be wasting time, money and effort exploiting and finding more hydrocarbons when we could be developing and encouraging greener, renewable options.

So it is on these issues that this blog will focus. I am an applied geophysicist-cum-geomechanical engineer, and I have some experience with monitoring fracking operations, so hopefully you'll find some informed opinions, ideas and facts on this blog. But I'm still not sure I have the answers to these questions. To frack or not to frack? That is the question. I intend to find out. On the way I hope to inform, engage and enlighten. And if I happen to amuse or entertain, I promise, it was entirely accidental....