The definitions of fracking in the UK are limited, ambiguous and inconsistent, a new study has said.
The paper, published this week in the journal Energy Policy, proposes a new definition to include any well stimulation technique that make rocks more permeable.
It would close loopholes in hydrocarbon regulations, deal with current confusion and include the use of acid to stimulate the flow of oil and gas, the paper said.
The UK’s legal definition of fracking is based on the volume of liquid used to fracture rocks and release oil or gas.
The paper’s authors – a campaigner, a lawyer and a geophysicist – described this as “simplistic and inadequate”.
The issue was critical, they said, because operations that qualified officially as fracking were often subject to stricter regulations and conditions, including baseline monitoring and site visits.
The moratorium on fracking in England, in force since November 2019, applied only to fracking that met the volume definition.
For operations that did not qualify, regulators had greater discretion on controls. Some operations may not need permits, monitoring or detailed impact assessments, the authors said.
“It is due to the lack of clear definitions around fracking and historical misinformation that there is a need for a new approach based on a single robust and quantified definition of unconventional hydrocarbon.”
They said the definition should apply to:
“All well stimulation treatments of oil and gas wells which increase the permeability of the target rock volume to higher than 0.1 millidarcies [a unit of permeability] beyond a 1 m radius from the borehole.”
Associated hydraulic fracturing
The UK’s legal definition of high volume hydraulic fracturing (HVHF) dates from the 2015 Infrastructure Act.
This definition, incorporated into the 1998 Petroleum Act, specifies that associated hydraulic fracturing uses more than 1,000 cubic meters of fluid for each [our emphasis] fracture stage or 10,000 cubic meters in total.
Operations that met this definition must have 12 months of baseline monitoring of methane in groundwater and ongoing monitoring of methane emissions to air. The Oil & Gas Authority and Environment Agency (EA) must approve a Hydraulic Fracturing Plan, which assesses the risk of seismic activity. The EA and Health and Safety Executive have committed to making site visits for new fracks.
The authors said of the volume definition:
“The 10,000 and 1,000 cubic metres volume thresholds are unrealistically high because many HVHF operations around the world would not be defined as fracking if these figures are used.”
None of the three high volume fracks in the UK since 2011 met the definition of associated hydraulic fracturing, they said.
Relevant hydraulic fracturing
In 2016, the definition was broadened in a set of regulations on fracking in protected areas. They specified that relevant hydraulic fracturing uses more than 1,000 cubic metres of fluid at any [our emphasis] fracture stage or more than 10,000 cubic metres of fluid in total.
Relevant hydraulic fracturing would include operations excluded from associated hydraulic fracturing if just one stage exceeded the 1,000 cubic metre limit, the study said.
But neither fracturing definitions would probably apply to acid stimulation because it often uses less fluid.
There is a different definition of fracking in the minerals section of national planning policy guidance. This focusses on opening, extending or creating fractures, with no reference to the volume of liquid.
This is broader still than the 2016 regulations. Operations outside those definitions, such as acid stimulation, could be included under the minerals guidance definition, the authors said, but this was not clear.
Planning applications for hydraulic fracturing would normally need to include a detailed study, known as an environmental impact assessment (EIA). But if planning authorities considered that acid stimulation, with its lower volumes, did not count as fracking, they would be less likely to require an EIA, the authors added.
Guidance from the Environment Agency describes a process of squeezing acid into rocks to enhance or create new paths to make the well more productive. The guidance does not specify volume, acid concentration or frequency of use, the study said.
“the definition of an ‘acid squeeze’ is ambiguous and may amount to an acid wash or acid stimulation in the form of matrix acidisation”.
This is significant, the study said, because activities considered to be an acid wash were treated as de minimis – having a negligible effect on the environment – and did not need an environmental permit. On de minimis operations, the EA does not monitor issues such as pumping pressure, acid volumes and frequency or timing of operations.
In 2019, the EA decided that a proposed acid squeeze operation was de minimis.
The authors said their proposed definition would:
- avoid arguments about how much water was required to define an HVHF threshold
- exclude activities, such as localised well-cleaning, involving water or acid treatments close to the borehole
- exclude stimulation used in other fields such as geothermal energy, water resources or water reinjection.
“[It] also circumvents the current confusion and obfuscation by going to the purpose of the various stimulation processes, whether they involve high volume hydraulic fracturing or acid stimulation, or other methods such as gas and electrical energy injection that have been tried in the past or could be tried in the future.
They also repeated a call for the 2019 moratorium to be converted into a ban that extended to all well stimulation treatments for unconventional hydrocarbon extraction.
Acid stimulation: Fracking by stealth continues despite the moratorium in Englanduntil 27 May 2021, when the accepted text version of the paper will remain available on the Brockham Oil Watch website
Study authors: Adriana Zalucka, of Brockham Oil Watch, Alice Goodenough, of Harrison Grant Solicitors, and David Smythe, Emeritus Professor at the University of Glasgow.