Fracking for shale gas: geologists demand more data for UK
The pad will evolve over these stages, requiring different services and skills at each stage
The main drill rig drills a well prior to the hydraulic fracturing process
Exploratory drilling is critical to assess recoverable UK shale gas reserves
Prof Richard Davies, ReFINE, wants answers to questions such as how close can we frack near a fault line?
We should know more about what lies underground, say geologists, before the UK government urges operators to submit fracking plans.
Fracking. The very word evokes pictures and emotions similar to the "mobile phone masts" of the early 1990s.
Hydraulic fracturing – or fracking – is a technique used to extract methane from shale rock and has attracted attention over concerns that it could trigger earthquakes or contaminate drinking water. The Internet abounds with videos of flammable water from taps, blogs about earthquakes and news of arrests after protests about fracking.
But despite the concerns, UK government is becoming increasingly pro-fracking, with the introduction of new planning regulations, tax break incentives and greater financial benefits for local authorities that allow fracking to take place. In January this year, the Prime Minister made his position on shale gas quite clear by saying: "We're going all out for shale."
Perhaps more surprisingly, in its most recent report, the Intergovernmental Panel on Climate Change (IPCC) stated that because a modern gas-fired power plant emits about half the carbon dioxide per unit of electricity than a comparable coal-fired unit, the use of shale gas could lower emissions where gas competes with coal.
Media outlets have since quibbled over whether or not this represents an endorsement of shale gas from the international environment group, but as geoscientist Professor Andrew Aplin from the Department of Earth Sciences, Durham University, UK, simply states: "Of course the ideal scenario would be to leave fossil fuels underground and turn to renewables to keep the lights on, but that is not a realistic option at the moment.
"It seems that the IPCC has realised it needs to take a more pragmatic approach and that we urgently need energy sources that will bridge our transition to less carbon-intensive energy sources," he adds.
Despite his call for pragmatism, Prof Aplin is one of many geoscientists and geoengineers seriously concerned about the lack of data available in the UK. Indeed, he believes the government is currently making policies without knowing all the facts.
"We know where our shale gas resources are, thanks to the work of the British Geological Survey (BGS)," he says. "But we have no idea of how much of these resources we can actually extract because we have not drilled enough exploratory wells.
"Estimates have been made, but these are based on figures from the US," he highlights. "This is a great starting point, but not good enough. We need more data before we can decide whether shale gas could, or should, be part of our energy mix."
Geologist Ed Hough, who coordinates shale gas research at the BGS, agrees. As he says: "We know where shale is in the UK and we are confident we know how much shale gas is in that shale, but until we drill wells to test the flow rate, we won't know how much we can access.
"In the US, recovery factors are between 8 and 29 per cent of resources, but there are important differences between the US and the UK that need to be taken into account."
For starters, UK basins are smaller and more fragmented than in the US, and UK source rock tends to contain less gas at lower pressure. A higher clay content in some rocks may also make fracking more challenging. And it is also known that shale in the north of England is much thicker than shale in the US, which means fewer wells may be needed in order to extract it.
High density drilling
The most obvious difference between the US and the UK, and one mentioned a lot in the media, is that the US is a more sparsely populated country than the UK and so fracking operations often go unnoticed by the public. According to Prof Aplin, in order to extract a significant amount of shale gas in the UK, "we will need a high density of drilling pads", which in a country as densely populated as the UK, could be an issue.
A shale gas pad is an area of land of around two hectares, which will feature a number of vertical wells. From each of these vertical wells, a number of so-called laterals – or horizontal wells – are drilled.
Prof Aplin quotes one estimate that suggests the UK would need up to 30,000 wells in order to make the most of its resources. "And with an estimate of six wells per pad, that's around 5,000 pads," he says.
Other estimates vary enormously. A report published by the Institute of Directors (IoD) in 2013 featured two scenarios: a high-case scenario, in which a single pad has 10 wells with four lateral sections each, and a low-case scenario where a single pad has 10 wells with one lateral section each.
Based on the high-case scenario, the IoD estimated that it would take 100 pads, with some 4,000 wells, to access enough shale gas to bring our gas imports down by 50 per cent by 2030.
To put the argument about population density and use of land into context, the IoD compared the amount of electricity that a shale gas pad could produce and compared it to the amount of electricity produced by a typical wind farm.
In the high-case scenario, with 40 wells, a pad can provide enough gas to generate 19,706GWh of electricity over its lifetime. A typical windfarm has 26 turbines and covers 545 hectares. Assuming it continues to generate the same level of electricity as it has for its first few years of operation, it could be expected to generate 3,719GWh over its lifetime.
Tackling the known unknowns
While all these figures and estimates paint a picture, they are based on US data, not UK data, making them effectively just guestimates, at best. Professor Richard Davies who leads the Researching Fracking in Europe project (ReFINE) is particularly concerned about the lack of UK data and the many "known unknowns". The ReFINE project aims to answer many of these fundamental questions, such as which faults are active in the UK and how close can we frack near a fault line and still be safe?
"There are basic questions that we still do not have the answers to," says Prof Davies. "One of the most important that industry is trying to answer is 'what is the flow rate of the shale resources that we have in the UK?'. As a geologist, there is only one way of answering that question and that is by drilling more wells."
Prof Davies was one of many experts that gave evidence to the House of Lords' Economic Affairs Committee, which recently published its report 'The Economic Impact on UK Energy Policy of Shale Gas and Oil'. The report criticises the "snail's pace of exploration" and urged industry to "get on with it".
It points out that, "with estimates of the UK's shale gas resource still incomplete, and little or no exploratory drilling and appraisal yet undertaken, there are no well-grounded assessments of economically recoverable reserves of shale gas".
According to Ken Cronin, chief executive of the UK Onshore Operators Group, an organisation that represents oil and gas operators including UK shale gas developer Cuadrilla, this is set to change. As he puts it: "Over the course of the next two to three years between 20 and 40 wells will be drilled for exploration."
But the Environment Agency told the House of Lords Economic Affairs Committee that "since the government gave permission for hydraulic fracturing in principle to resume [in December 2012], we ' have not yet received any permit applications to undertake hydraulic fracturing".
The delays seem mainly due to uncertainties over regulatory requirements and Cronin admits that it will take around a year to go through the necessary paperwork before companies can begin to think about drilling. After all the regulatory procedures have been overcome, UKOOG estimates that it will take six years to complete the exploration and development stages to bring a single pad with 40 lateral wells into production.
While regulatory issues are a hurdle, Cronin believes it is only right that the industry is heavily regulated. "In the US there is no national regulation and this is one of the reasons the public has become mistrusting of the industry," he says.
For example, in the US, it is common practice for waste solids from the fracking process to be stored in a reserve pit next to the drilling rig. UK regulations would not permit this, instead requiring that such wastes are treated at an appropriate facility.
Also, in the US, operators are not required to disclose the composition of the fracking fluids they use, whereas in the UK, businesses will be required to disclose this information. And the venting of methane would also not be permitted in the UK except in an emergency.
"It is regulation and transparency such as this that will hopefully help increase the public's confidence in fracking," points out Cronin.
Building supply chains
Based on the IoD's 100 pads scenario, an Ernst & Young study, commissioned by UKOOG, estimates that to drill up to 4,000 laterals over an 18-year timeframe the industry will need to spend in the region of £33bn in supply chain activities.
The study, published in April 2014, estimates that at its peak this supply chain can be the source of around 64,000 jobs directly linked to shale gas exploration sites, indirectly in the supply chain or supporting services as a result of this new investment activity. However, the study warns that the UK needs to work now to lay the foundations for the necessary infrastructure, supply chain standards and skills requirements before developers look overseas.
The study found that £17bn worth of specialised equipment and skills for hydraulic fracturing would be needed. Some £2.3bn worth of steel would be required for 12,600km of steel casing of specific diameter and quality.
The report confirms that the UK has the ability to produce this amount at the right quality, but highlights how further research and development is required to make it a reality. Other opportunities include the potential for a new £1.6bn rig manufacturing industry and a £4.1bn waste, storage and transportation requirement. Overall, UKOOG estimates that to bring a single pad on-stream will require a hefty £333m.
"It is early days," says Cronin. "We have a lot to do in terms of working with the communities involved, understanding geology, flow rates and the cost base."
For example, UKOOG recognises the need to define common pad and hydraulic fracturing standards as well as the development of new fracturing equipment and new technology around waste water treatment and other environmental considerations.
At the same time, UK hydraulic fracturing engineers are in short supply. The lead time to develop a hydraulic fracturing engineer with the right level of experience could be as long as five years and developing a new training programme could take up to four years.
In addition, skills shortages already exist in related offshore and chemical industries, which could be further exacerbated if shale gas really takes off. For its part, UKOOG plans to work with relevant bodies to define a set of standard skills and qualifications for the different staff needed to work on a shale project.
There is a lot still to do before we know whether shale gas can keep the lights on in the UK. With transparency, open discussion and robust regulation, onshore operators hope to diffuse fracking opposition as the mobile telecommunications industry did in the 1990s.
For now, researchers, politicians and industry are agreed on one key point – only exploratory drilling can tell what the recoverable reserves really are. So, is it, at long last, time for industry to act?
Shale gas risks
ReFINE is pan-European, independent research consortium launched in 2013 and led by Durham Energy Institute. It focuses on the issue of shale gas and oil exploitation using fracking methods and its potential risks. These include aquifer contamination, induced seismicity, fugitive emissions, traffic and public perception.
Recent findings reveal that there is a less than a 1 per cent chance of a stimulated hydraulic fracture propagating upwards for more than 350m, and that the maximum recorded distance of such a fracture is less than 600m. This makes contamination of drinking water very unlikely as fractures are not tall enough to reach water aquifers.
Meanwhile, other studies indicate that well barrier failure is likely to occur in a small number of wells and this could in some instances lead to some form of environmental contamination. As such, systematic, long-term monitoring data for both active and abandoned well sites should be in the public domain.
However, based on current data, the likelihood of fracking causing seismicity is very small, though it cannot be ruled out. When compared with other sources of induced seismicity, such as mining and reservoir impoundment, hydraulic fracturing has been, to date, a relatively benign mechanism.
Shale gas plans
At the time of writing, UK oil and gas operator, Cuadrilla, was preparing to submit planning applications to drill, hydraulically fracture and test gas flows at two sites in Lancashire. Gas flow rates would be tested for up to 90 days.
The company has been consulting with local residents near the villages of Roseacre and Little Plumpton, writing to more than 9,000 households and holding a variety of events to give residents the opportunity to find out more about plans. Some homeowners have been described as hostile in media reports.
Even with planning permission in place, the company would then have to obtain numerous permits from the Environment Agency.
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