Proponents of the oil drilling at Horse Hill frequently try to reassure locals by explaining that it’s “not fracking”.

The Infrastructure Act 2015 introduced a new definition of ‘hydraulic fracturing’. Now an operation will only be defined as fracking if:

• it is below 1,000 metres depth
• it uses 1,000 cubic metres of fluid for each stage, or more than 10,000 cubic metres in total.

This means that companies can now undertake low-volume fracking without needing to apply for a fracking licence.

When asked to comment on the new definition, Professor of Geology, Stuart Haszeldine (University of Edinburgh) said, “I 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).”

Preese Hall: “not fracking”?

Under these criteria, no fracking has taken place in the UK. Even Cuadrilla’s operation at Preese Hall Farm in Lancashire in 2011 (which the government described as hydraulic fracturing previously and Cuadrilla referred to as “hydraulic fracture operations” in its own report) does not count.

At Preese Hall Farm, one of the stages was only 759 cubic metres and the total volume was 8,399 cubic metres so on both these counts, it would now not be considered ‘fracking’.

Yet this operation triggered two serious seismic events and led to the well being taken out of commission and a national moratorium on the process.

If not fracking, what is it?

At Horse Hill, the companies are looking for conventional oil in the Portland Sandstone. But the main target is the Kimmeridge Clay shale formations, which cover a large part of the Weald. This is ‘tight oil’ or ‘shale oil’.

Tight oil is oil trapped in low permeability rocks. Extracting it usually requires similar techniques to shale gas: the drilling of long horizontal laterals, hydraulic fracturing or acid stimulation, and the drilling of a densely-spaced patterns of wells.

“a rose by any other name”

“What’s in a name? that which we call a rose
By any other name would smell as sweet”

…said Juliet, in William Shakespeare’s play. She’s right. Call a rose a skunk cabbage and it would still smell good. Call low-volume fracking and acid stimulation what you like, they still carry the same risks.