Tuesday 29 May 2012

Shale Gas, Climate Change and Energy Bills

Many readers will remember my post outlining why shale gas is a good thing when it comes to reducing greenhouse-gas emissions. The reason I say many is that, according to my blogger stats page, this is by far my most popular post. So I thought I'd provide some more background to that previous post. Much of this information is lifter directly from John Hanger's excellent blog (I'd recommend it highly to anyone interested in US energy policy).

Looking at the latest numbers for US electricity generation, coal is at 37%, while gas is at 28%. This is the lowest share for coal in 35 years! Coal is down 21%, while gas is up 30%. Clearly, as you'd expect when the large quantities of shale gas being produced have pushed US gas hub prices below $2, power generation companies prefer to burn gas because it's cheap.

If you don't believe the EIA, why not look at figures from the Sierra Club, a noted environmental
organisation (no industry shills here). They keep a record of the amount of CO2 emissions that have
been avoided by coal plant closures and cancellations. Since 2000, the share of coal in US electricity
generation has dropped from 52% to 37%. 10% of that gap has been taken up by gas. And, unless you're Howarth or Ingraffea, burning gas produces significantly less CO2 than coal, so we can reduce our greenhouse-gas emissions. The Sierra Club estimate that the net CO2 abatement from this switch from coal to gas has prevented 225 million tons of CO2 per year. This is not small beer we're talking about here!

And what about the influence on renewable energy - surely low gas prices have scuppered investment in the renewable energy we ultimately need? Well, during this shale gas glut, from 2008 to present, wind energy production has doubled and solar power increased 8-fold. Renewable energy is dependent mainly on government subsidies and supportive policies, so as long as these remain available, renewables are relatively protected from the kind of market forces that have seen the switch from coal to gas. If renewables were exposed to market forces, they'd soon struggle regardless of whether gas is $2 or $6.

So what are we doing in the UK? Well, we've announced our new energy policy this week. I don't pretend to be an expert in these more complex legislative things, but the general consensus is that this bill is supportive of nuclear power and wind power. One good thing is that under the proposals it's difficult to see any new coal power being built without carbon capture and storage. However, it seems that the government has significantly underplayed the potential for shale gas in a future energy mix.

Perhaps the most notable example of this was the noises emerging after a weekend meeting between Downing Street and a selection of industry experts, which suggested that shale gas in the UK won't really amount to much. What's really interesting about this meeting is who was there, and more importantly, who wasn't. Who was there? Representatives from Shell and Centrica.

Shell have barely any shale gas interest, but plenty of large conventional gas fields in the Southern North Sea. High gas prices are good for them. Centrica (i.e. British Gas as was) sell us gas to heat our homes. High gas prices are good for them. Meanwhile neither Cuadrilla, Igas, Coastal or Dart Energy were involved. These are the 4 companies buying licenses and looking to drill for shale gas in the UK. Cuadrilla are the only company to have sunk a well into the Bowland shale, which will probably be the most productive UK shale deposit.

So, if you invite 'experts' from two companies with a vested interest in maintaining high gas prices, while ignoring the companies that are actually making assessments on the ground, it's hardly surprising that you'll end up with a rather negative view of the potential for shale gas in the UK. Cuardilla's latest estimates for shale gas are as much as 5.6 trillion cubic meters. Comparing the figures between the Bowland shale and the Barnett, which is the one of the largest producing shale bodies in the US reveals many similarities, which suggests that there may well be a lot more gas under Blackpool than the likes of Shell and Centrica would like. These figures seem extremely positive to me.

ParameterBowlandBarnettWhy important
Thickness1000m300mThe thicker the shale, the more there is
TOC (organic content)1-5%1-6%High organic content means more gas can be created
Fractured carbonate bandsYesYesPre-fractured bands help the gas to flow to the well-head economically
Vitrinite reflectance1-1.61-1.4Vitrinite tracks burial depth. The rocks must be buried and heated to turn organic matter into oil/gas

Sunday 13 May 2012

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.

Friday 11 May 2012

5 minutes of fame in the local papers......

Those of you with longer memories will remember my 'disgusted from Tunbridge-Wells' style outburst about reports in the local papers (the Bath Chronicle and also the Wells Journal). I wrote to the papers, but after a brief acknowledgement, I heard no more from them, and assumed that my contribution had been assigned to the dustbin.

However, I was recently chatting to a friend who, apparently, must be an avid reader of the local papers, because it turns out that my letter did indeed make it into the Bath Chronicle and the Wells Journal. It seems I also went one better and made it into the Somerset Guardian. Heady times indeed. What's even more exciting is that people must have read my letter, because this person wrote a response to it, and this op-ed piece seems to 'borrow' a lot from it.

Steve Sparks, one of the world's leading volcanology experts (so famous he actually has a Wikipedia page), also wrote a similar letter, also published by the Bath Chronicle.

Anyway, it seems I had my 5 minutes of fame and yet was completely unaware at the time. Still, glad I had the chance to put my opinion out there.