Saturday, 19 April 2014

Recent Earthquakes in Ohio

The Associated Press reports several earthquakes in eastern Ohio that have been linked to shale gas extraction. If true, this represents the 4th time that hydraulic stimulation in shales has been associated with seismic activity. This follows Preese Hall, Lancashire, the Horn River Basin, Canada, and Garvin County Oklahoma.

Note that it is important to differentiate between earthquakes triggered by hydraulic stimulation (i.e. fracking) and those triggered by underground disposal of large volumes of waste fluids, which is not being considered in the UK. It is the underground waste disposal wells that have been attributed to the increase in mid-continental seismicity seen in the USA.

Attributing cause and affect with respect to earthquake triggering is a difficult challenge. Frohlich and Davis (1993) came up with a series of 7 questions that are still commonly used to attribute "induced" earthquakes. These are:

  1. Are these events the first known earthquakes of this character in the region?
  2. Is there a clear temporal correlation between injection and seismicity?
  3. Are epicentres near wells (within 5km)?
  4. Do some earthquakes occur at or near injection depths?
  5. If not, are there geologic structures that may channel flow to earthquake sites?
  6. Are changes in fluid pressure at the well toe sufficient to induce seismic activity?
  7. Are changes in fluid pressure at hypo central locations sufficient to encourage seismicity? 
However, without good quality seismic data, these questions can be difficult to answer.

1. Ohio DNR provides a handy interactive earthquake map. The recent events are in the east of Mahoning County, on the border with Pennsylvania. In 2010/2011 a series of earthquakes occurred a few km to the northwest. These Youngstown events were associated with a waste disposal well. More seismicity is located 50km to the north. Again, many of these events have been linked with injection wells that were active in the 1980s/90s, disposing waste from chemical plants in Ashtabula and Perry.  So these are not the first events of this character in the region. However, the majority of seismic activity in the region is injection induced.

2. Injection schedules are not publicly available for wells in the area. However, the fact that the DNR have linked the events to hydraulic stimulation would imply that a temporal correlation exists.

3. The Ohio DNR provide interactive maps for both wells and earthquake locations. Well worth having a play with both. Sadly though it is not possible to overlay them both, so the following images show the earthquake epicentres and the well locations.

Firstly, note the large number of green dots in the centre of the well map. As I understand it, these are conventional wells drilled into a gas-bearing sandstone formation in the 1980s/1990s, so there is already a large amount of oil field activity in the area. Recent horizontal wells targeting shale layers are marked as grey arrows in the lower right part of the map. The earthquake epicentres can be seen in the upper plot, and appear to be in a similar location. So there does seem to be a clear spatial correlation with recent activity.

4. Earthquake depths can only be accurately determined if a local monitoring network is in place. Because this data is not available, the earthquake depths are not constrained. If you select the quakes in the ODNR viewer (use the 'i' tool) you will see all the depths set to 5km. This is seismologist short-hand for the depth being unconstrained. So we can't answer question 4.

5. For similar reasons, we don't have enough data to answer 5 either.

6. Hydraulic fracturing uses pressures high enough to create fractures in the rock. Therefore, for stimulation the answer to 6 will always be a yes - pressure at the well will be sufficient to trigger seismicity.

7. However, the press pulse is usually limited to a small area around the well, The "stimulated reservoir volume" typically extends only a few hundred meters from the injection point. Because these earthquakes are detected and located using distant seismometers, there can be over a kilometre of error on event locations. Therefore it is not possible to know whether the detected events are close enough to the wells to be within the stimulated zone. 

So to respond to the Frohlich criteria, we have 3 yes, but 4 don't knows. In all probability it would appear that these events have been induced by stimulation. But these events show the importance of good quality seismic monitoring during hydraulic stimulation. Fortunately, in the UK all stimulations will have to be monitored in this way. You can read about how Bristol University deployed seismometers to do this at Balcombe here.

As for the wider implications? In terms of energy technologies, fracking still doesn't make it into the premier league (to quote Prof Richard Davies). Hydroelectric dams, conventional oil and gas extraction, coal mining, geothermal, waste fluid injection (which would include carbon capture and storage) all have demonstrated potential to trigger seismic activity. Anything that changes the state of stress in the subsurface can cause a fault to reactivate. Crucially, a fault near to it's critical failure point is required. These activities do not create earthquakes "from scratch". They bring forward in time an earthquake that would have happened at some point in the future (maybe in a year's time, maybe in 1000 years time, we don't know). This is known in seismology as "clock advance"

It has been suggested that the maximum earthquake size that can be triggered is related to the injection volume. The larger the injection volume, the larger the earthquake that can be produced. This is why disposal wells, which are taking the waste fluid from hundreds of individual wells, have been so much more seismogenic that fracking wells. With this in mind, hydraulic stimulation for shale is unlikely to trigger earthquakes with magnitudes larger than magnitude 3.0. This was one of the conclusions of the Royal Society report into shale gas. All of the events recorded in Ohio had magnitudes between 2.0 and 3.0.

Magnitude 3 events are large enough to be felt by people at the surface, but not sufficient to cause damage to buildings or surface structures. Earthquakes (naturally occurring this time) have made the news in the UK this week, with a magnitude 3.5 event occurring in Rutland. Magnitude is a logarithmic scale, so the Rutland event was was 6 times larger than the largest Ohio event. The Rutland event has been described variously as "it felt a bit like standing right next to a tumble drier", "it sounded like a loud train rumbling", while England fast-bowlers past and present seemed particularly involved, with Matt Hoggard describing it as “like a massive train going past outside”, and Stuart Broad noting that his mum's tea was knocked off the table.

To conclude, it seems likely that the quakes felt in Ohio were triggered by stimulation. However, we really need better data, which is why monitoring will be required for all operations in the UK. The overall context is that shale extraction is no more likely to trigger seismic activity than other forms of energy production that we are familiar with in the UK, and very unlikely to trigger events large enough to cause damage at the surface.

Monday, 14 April 2014

IPCC on natural gas

The "Summary for Policymakers" of the final part of the IPCC 5th Assessment Report has been released today. The IPCC AR5 is split into 3 volumes: the first focused on the physical evidence for climate change; the second on the impacts of climate change. This final part focuses on what we can do about it.

Unsurprisingly, the report calls for substantial increases in proportion of electricity generated from renewable sources. It also calls for increased levels of nuclear energy as "a mature low‐GHG emission source of baseload power".

Of most interest to this blog is the paragraph on natural gas:
GHG emissions from energy supply can be reduced significantly by replacing current world average coal‐fired power plants with modern, highly efficient natural gas combined‐cycle power plants or combined heat and power plants, provided that natural gas is available and the fugitive emissions associated with extraction and supply are low or mitigated (robust evidence, high agreement). In mitigation scenarios reaching about 450 ppm CO2eq concentrations by 2100, natural gas power generation without CCS acts as a bridge technology, with deployment increasing before peaking and falling to below current levels by 2050 and declining further in the second half of the century (robust evidence, high agreement).
This is a very strong statement. Not only must natural gas electricity generation stay at current levels, but its deployment must increase in the near term, with the amount of natural gas-fired power generation only returning to and dropping below current levels by 2050, almost 4 decades from now. This is true regardless of whether carbon capture technology is deployed at gas-fired plants. Development of CCS would further increase the need for gas:
Carbon dioxide capture and storage (CCS) technologies could reduce the lifecycle GHG emissions of fossil fuel power plants (medium evidence, medium agreement).
Note that the report categorises how strong the evidence, and the degree of consensus, for each statement it makes. These statements on natural gas have robust evidence, and a high level of agreement.

Also of interest is the caveat "provided that natural gas is available". The report sticks to discussing natural gas in general: it does not directly consider from where this gas will be sourced, and does not mention shale directly. However, it is clear that to have "deployment increasing before peaking and falling to below current levels by 2050", shale gas will have to be developed extensively.

While shale isn't directly mentioned in the SPM, comments in the press conference made by Ottmar Edenhofer, co-chair of the report, bear out these implications in terms of shale gas.

These comments have generated headlines this morning (Mail, Independent, Times, CityAM). The IPCC WGIII press conference is available online - the comments on shale come in at 53:42 (emphases mine):
We have in the energy supply also the shale gas revolution, and we say that this can be very consistent with low carbon development, with decarbonisation. That's quite clear.  But it is important to understand that the shale gas revolution has a different impact in mitigation or baseline scenario. In a baseline scenario if you have an additional supply of fossil fuels this will not help in the end, because if somebody deploys gas so other parts of the world might increase coal and in the end you're back in the business as usual scenario, and shale gas will not help. But gas can be very helpful as a bridge technology in mitigation scenarios, and this has been explained in the energy supply sector.  

Monday, 7 April 2014

Caroline Lucas, Green MP: "It's not that fracking itself is necessarily worse than ordinary gas extraction"

An interview in the Guardian with Caroline Lucas, the UK Green Party's only MP, makes for interesting reading. She's currently awaiting trial for her role in the protests at Cuadrilla's Balcombe drilling site.

She has some interesting comments about shale gas development in the UK:
For Lucas, the big problem with fracking has nothing to do with the risk that it will cause earthquakes, contaminate the water table or pollute the soil. In fact, she thinks it possible that stringent regulations could minimise those risks. "It's not that fracking itself is necessarily worse than ordinary gas extraction. It's the fact that we're just about to put into place a whole new infrastructure for a whole new fossil-fuel industry, at exactly the time when we need to be reducing our emissions." The problem, in other words, is climate change.
I've long been of the opinion that, at the upper levels of various NGOs and political groups, the primary opposition to shale gas is derived from a the climate change angle, not local pollution. The scare stories about earthquakes and pollution are a stalking horse for the real issue. Climate change concerns are unlikely to mobilise local support in any significant way, hence the need to exaggerate local impacts in order to foment local opposition. It's refreshing that Caroline Lucas has come clean about this.

Sunday, 6 April 2014

Image of the day: CO2 emitted, and CO2 reserves

Shale gas, where it displaces coal in the electricity generation mix, presents a substantial reduction in CO2 emissions. These two images highlight the state of affairs in terms of global CO2 budgets. The first image shows CO2 emissions from fuel source and from country (in 2008). Clearly, Chinese and American coal are by far the biggest culprits. The second shows an estimate of the amount of CO2 embedded in fossil fuels as yet unburned. This presents us with a clear choice - if we are to continue burning fossil fuels, we should be choosing to burn gas.

Friday, 4 April 2014

Image of the Day: Nat Gas vs Renewables in the Developing World

Imagine you had $10 billion to invest in providing electricity to people in the developing world who currently go without.

The lack of electricity in the developing world is a major issue. Almost 3 billion people burn twigs and dung to keep warm and heat their food. This causes indoor air pollution, which has been estimated to cost over 4 million lives per year. Electricity allows refrigeration to keep food from spoiling and rotting. Refrigeration is also vital to keep certain medicines in good condition. Electricity powers computers and phones that allow people in developing countries to connect to the world.

The Center for Global Development have worked out how far your $10 billion would go if you were to use renewables, or were to use gas, or some mix of the two. How many people could you connect to an electricity supply?

If $10 billion of your aid and development money is invested in renewables in the developing world, it will provide electricity to 20 million people. If that money is invested in gas-fired power, it will provide electricity to 90 million people. Bjorn Lomborg provides a neat summary of the issues at stake that I recommend reading. 

Thursday, 3 April 2014

Balcombe's solar plant: A footprint comparison

In this week's news, the residents of Balcombe are looking to raise funds to install solar panels to power the village. The initial plan is to raise £300,000 for enough panels to power 7.5% of the village, with the intention of continuing as far as possible towards 100%.

On the one hand, I think community involvement in energy generation is a good thing. On the other hand, these projects are made financially viable via subsidies added to everyone's energy bills. Indeed, project documentation makes clear that their efforts are only made financially viable via the feed-in tariff.

The regressive way that renewable projects are currently funded is something that irks me. We spent time in Balcombe last year deploying seismometers during Cuadrilla's drilling, and it's a typical well-heeled home county village. Current solar subsidies have the effect of taking money from the average bill-payer, such as myself, who is a long way from owning any property at all, let alone a property suitable for solar panels, and handing it on a plate to wealthy landowners: people who already own buildings with large roofs on which to install panels.

That issue aside, this provides an excellent opportunity to compare the footprint of different energy sources. While the group itself don't make the connection, the way the story has been reported gives the impression that the solar developments represent in some way an alternative to the drilling conducted last summer, with a significant portion of the village opposing Cuadrilla's plans to conduct flow-tests on the well.

With that in mind, how do the two plans stack up in terms of the energy they might provide?

Monday, 31 March 2014

Image of the day: 2,000 onshore UK wells

Onshore drilling is not new to the UK. Approximately 2,000 wells have been drilled onshore in this country, mainly in the 1970s - 1990s. This map shows where they are, coloured by the year they were drilled (pre-1949 are cyan, 1950 - 1979 are yellow, 1980 - 1999 are (light) pink, and 2000 - 2013 are (dark) purple).

To download Google Earth .kml files for these locations, use the following links: pre-1949, 1950-1979, 1980-1999, 2000-present.

Friday, 28 March 2014

ReFINED well integrity

This week's big news was the release of the latest paper from Durham University's ReFINE Group (Research on Fracking IN Europe - academics love a dodgy acronym!). In it, they compile statistics on well integrity from a range of sources, as well as looking at well abandonment and orphaned wells (where the company owning a well goes bust, leaving a well with no-one to look after it).

This follows ReFINE papers on induced seismicity, and on hydraulic fracture height growth. Their approach in each of these cases is to use as much data as they can possibly get their hands on, with little thought for quality control, or on whether they are comparing apples with apples. In their own words:
This paper draws on a variety of datasets, mostly published, but in some instances sourced from online repositories or national databases, and follows the approach of Davies et al. (2013). In that study, the risk of induced seismicity due to hydraulic fracturing was reviewed, and intentionally included all datasets in the public domain that were considered to be reliable, rather than de-selecting any data (Davies et al., 2013). This inclusive approach has a drawback because well barrier and well integrity failure frequencies are probably specific to the geology, age of wells, and era of well construction (King and King, 2013). A wide range of failure statistics is therefore reported, and although they are presented on a single graph to show the spread of results, this is not intended to imply that direct comparisons between very different datasets (i.e. size, age of wells, geology) can be made.
This means that data from recent drilling in the Marcellus (which is probably relevant) is presented alongside less relevant data from offshore wells (drilling offshore is always a more challenging prospect, with hundreds of meters of water between your platform and the well-head), from China, or even from the 1920s in California.

Image of the day: First Frack!

This is a photo taken of the first hydraulic fracture stimulation operation, performed in Kansas in 1947 by Stanolind Oil.

Fracking has been around for many decades. However, it has evolved significantly during this time. In 1947, Stanolind used 1,000 gallons of napalm-thickend gasoline. Modern stimulations in shale reservoirs might use 1,000,000 gallons of "slick-water" - 99% water with chemical additives such as guar gum, polyacrylimide and hydrochloric acid.