New rules regulating UK shale oil and gas production, introduced last week under the Infrastructure Act, changed the definition of fracking in a way which may by-pass previously agreed environmental safeguards, thus opening a loophole for less secure operations.

Fracking faces more onerous regulations compared with conventional onshore oil and gas. These regulations include: required disclosure of fracking fluids; greater monitoring of well drilling; and higher standards for casing and lining of bore holes, to prevent groundwater contamination.

It’s not clear how much, if any, of those regulations would apply to fracking now falling outside the new definition, which is based on volumes of fluids used. The re-definition may create a pathway for unscrupulous companies to exploit in future, and could therefore be an unhelpful strategy, if Britain is serious about its claim to be the world’s best-regulated fracking industry.

Hydraulic fracturing, more commonly known as fracking, is the process where water, sand and trace amounts of chemicals are injected deep underground through a borehole to create fractures in shale rocks containing trapped oil and gas, allowing the valuable hydrocarbons to be produced. Combined with advances in drilling technology which now allows boreholes to be turned horizontally through the shale rock underground, the fracking process has proved to be extremely effective at producing large quantities of oil and gas, particularly in the USA. However, the process is not without controversy, especially in the UK. This is the result of several undesirable experiences in the USA, where spills of chemical additives for the injected fluid have caused local groundwater contamination, along with a handful of cases of stray methane gas leakage to the surface, combined with a growing and vocal anti-fossil fuel protest movement.

The case for shale gas in the UK is not helped by the fact that the first shale gas borehole in the UK to be “fracked”, in 2011 at Preese Hall near Blackpool triggered several small earthquakes. This prompted the process to be suspended in the UK between June 2011 and April 2012 whilst a detailed review of the fracking process was undertaken and a number of safeguards and new regulations where introduced. Despite strong government support for the industry, which includes tax boosts for councils willing to approve projects and the UK Prime Minister, David Cameron, stating that his government is going “all out for shale”, progress of UK drilling for shale hydrocarbons has stalled over the past four years since 2011. That is in distinct contrast to the ultra-rapid developments in North America, which transformed the wealth of many rural communities in a matter of months.

Deep skepticism has taken hold amongst many concerned UK citizens, leading to “activisation” and well organized protest and protection groups. Several applications have been made to drill “fracking” wells but all to date have been successfully opposed by citizens and councils. Imagine, then, if fracking boreholes were no longer fracking boreholes, but suddenly became normal oil and gas boreholes. These public opposition problems would disappear overnight and much less legal challenge could be made. Here, we outline how recent UK legislation appears to have performed just such a magical reclassification.

According to the United States Environmental Protection Agency (EPA), Hydraulic fracturing is defined as a stimulation technique used to increase oil and gas production from underground rock formations. According to the UK Infrastructure Act 2015 which was enacted on the 6th April 2016, hydraulic fracturing of shale in the UK is now a process involving (or expecting to involve) the injection of more than 1,000 cubic metres of fluid at each stage (or expected stage), or injection of more than 10,000 cubic metres of fluid in total (Fig. 1). Given the vast amount of shale gas and oil produced from the hydraulic fracturing of shale rocks in the USA over the past decade, it is somewhat curious to us as to why the UK has decided on such a different legal definition.

Fig. 1 – The new legislative text as written in the UK Infrastructure Act, 2015, enacted 6th April 2016.

Fig 1 Haszeldine

We have been involved in research into shale gas and related research over the past three years and have not discovered any argued definition to explain how or why these numbers were chosen. Or, indeed, why volumes of fluid are chosen at all, when the geological effects of fracking are really a consequence of strain rate (i.e. “speed” of imposed deformation of the rock). It is important to understand that hydraulic fracturing at a well pad for horizontal shale gas wells is not a “one shot” process. It is performed in stages, as the length of the boreholes usually exceeds several kilometres, it is usually not possible to maintain pressure sufficient to stimulate (frac) the entire length of the horizontal section over the borehole in a single stimulation (frac) event. Shorter sections of 20-40 metres are blocked off (packed) before the high pressure water, chemical and proppant sand mix is injected at pressures equivalent to 3km of burial. As such, there could be as many as 10-20 stages (fracs) per well. This means that a fracking operation can be classified according to amount of water used for each frac stage or a total volume of water used for the complete fracking operation.

In attempting to understand if there is a historical precedent for this legislation we have examined the volumes of water injected during hydraulic fracturing operations in both the UK and USA. During the only fracking operation performed on a shale formation in the UK so far, at the Preese Hall-1 well, Cuadrilla injected a total volume of 8,399 m3 of slickwater, below the 10,000 m3 now set as the UK limit to classify the operation as hydraulic fracturing. However, in the 5 separate stages of fracturing that they performed, 4 of them involved the injection of more than 1,000 m3 of slickwater, sand (proppant) and chemical additives (Fig. 2), meaning parts of the operation could still be classified as hydraulic fracturing under the new definition. Importantly, the lowest volume of slickwater injected was 759 m3, showing that it is still possible to effectively hydraulically fracture shales at those much smaller volumes. As this is the only operation of this type to have been completed in the UK, and that it was somewhat unsuccessful, it is not sufficient to use this single example to understand the new UK legislation.

Fig. 2 – Preese Hall-1 treatment summary from Green et al., 2012

Fig 2 Haszeldine

Looking to the USA, the volumes of water injected to perform hydraulic fracturing treatments between 2000-2010 have been compiled by the USGS. This data shows that of hydraulic fracturing treatments performed on 17,266 horizontal gas wells over those 10 years, 7,643, some 44%, were completed by the injection of less than 10,000 m3 of water. When it comes to the 4,555 horizontal oil wells which were hydraulically fractured over the same period, 4,044 out of them, some 88 %, involved the injection of water volumes below 10,000 m3. This means that under the new UK law almost a half of the gas wells and nearly 90% of the oil wells which were hydraulically fractured in the USA over this decade would now not be classified as”fracked”.

It is fair to say that the injection water volumes used to perform hydraulic fracturing operations in the USA have increased since 2010, with average volumes in 2012 ranging from 5678m3 in the Bakken Formation, up to 21,576 m3 in the Haynesville Formation according to the USGS, although the actual number of wells fractured in each shale formation is not provided. The average total volume injected into the Barnett Shale for fracking wells is only slightly above the new UK limit definition at 10,599 m3. Unfortunately, to our knowledge there is no detailed breakdown of the volumes of water injected per hydraulic fracturing stage in the USA so it is not possible to examine this in detail to see how the new UK regulation compares. However, it has been cited that 378 m3 is required to fill a typical well bore prior to hydraulic fracturing and that typically a single stage of the process can be undertaken with 250 to 4000 m3 of fluid. Hence, it is crystal clear that effective hydraulic fracturing can be undertaken using volumes per stage of under 1000 m3 and using under 10,000 m3 in of injected fluid in total, so it is surprising that the UK Government haven taken it upon themselves to exclude operations using these lower injection volumes as being classified as hydraulic fracturing.

Given the public concern about the process in the UK, it appears to us that the adoption of these new rules and definitions, without a clear supporting scientific argument, explanation, and justification, is potentially very unhelpful. This risks increasing the negative public perception of the process, not decreasing it. It is evident that the great majority of “fracked” well and horizontal laterals in the USA have been securely fracked, with good borehole design, correct casing and cementation, and good operational practice, with no adverse effects. We wonder if this could be a move to enable valuable measurements of scientific and industry data to be gathered through smaller hydraulic fracturing operations that can now be undertaken without special planning permission? However, we fear that this will be perceived as clandestine re-defining to administratively remove fracked boreholes from official existence, so that fracking in the UK is air brushed out of the future. Much more debate is needed to understand why this “definition” is needed, why it is so remarkably different to that of the USA, and why it ignores fluid pressures and rates of injection.

In conclusion, it is difficult to argue that this is anything other than part of the governmental obsession to ease the pathway for large scale fracking in the UK, as part of their drive to “go all out for shale”. In our opinion this appears to be a cynical swerve around the planning and judicial rules of precedent, to enable drilling and smaller scale hydraulic fracturing in areas where many members of the public are opposed to that activity. That is no way to win respect, confidence or hearts and minds. This is either a bad law, or a misinformed law, and needs to be cancelled immediately.

Dr. Stuart Gilfillan and Prof. Stuart Haszeldine are based at the School of GeoSciences, University of Edinburgh    Send article as PDF   
  • Tags:
  • Britain ,
  • Europe ,
  • germany ,
  • natural gas ,
  • oil ,
  • oil price ,
  • shale ,
  • shale gas ,


  1. I would question the argument regarding Preese Hall not being regarded as fracking. The single stage where udner 1000 cu m was used was the first fracking attempt after the April 1st seismic event triggered by the PH frack, and after it became known that the PH well casing was deformed. The logical conclusion here is not that fracks can take place below 1,000 c m, but that the operator here was employing caution. The law covers not actual but expected fracking volumes and it would have been fully expected earlier that and in the fracking plan that 1,000+ cu m would have been used.

    It is also significant that as regards total volume the expected total volume would have been over 10,000 cu m. It was only the fact that the May 27 job triggered another significant seismic event which prevented further frack stages. As evidenced by the DFIT that Cuadrilla carried out a coupole of days later, they fully intended to frack further, but pressure caused them to abandon the next job and indeed the well.

    The authors also fail to recognise that fracking at deeper depths requires more frack fluid (as witness eg the fracking plan for Kirby Misperton, which apart from the deepest injection plans to use under 1,000 cu m). Also that fracking deep horizontal wells will similarly require more frack fluid. Nothing in this is as “crystal clear” as the authors suggest, although I agree 100% that the government has introduced a totally artificial “definition” of fracking which is contrary even to the Environment Agency’s understanding, as demonstrated by the grant only on 11th April of the Kirby Misperton waste permit.

Leave a Reply