Environmental Engineering Reference
In-Depth Information
additives will be fully disclosed. As a result of this and the likely
public concern relating to some of the additives, companies working in
the UK are likely to invest in ''green'' or non-toxic alternatives wherever
possible.
The fracturing fluid that Cuadrilla has used at the Preese Hall exploration
well site, and plans to use at future exploration well sites, is composed al-
most entirely of fresh water and sand. Cuadrilla also has approval to use the
following additives:
Polyacrylamide (friction reducer)
Sodium salt (for tracing fracturing fluid)
Hydrochloric acid (diluted with water)
Glutaraldehyde biocide (used to cleanse water and remove bacteria)
So far, as additives to fracturing fluid, Cuadrilla has only used poly-
acrylamide friction reducer along with a miniscule amount of salt, which
acts as a tracer. Cuadrilla have not needed to use biocide as the water sup-
plied by United Utilities to their Lancashire exploration well sites has already
been treated to remove bacteria, nor have they used diluted hydrochloric
acid in fracturing fluid. Additives proposed, in the quantities proposed, have
resulted in the fracturing fluid being classified as non-hazardous by the
Environment Agency.
2.2.2.4 Hydraulic Fracturing
The issue of hydraulic fracturing causing earthquakes came to prominence
in the UK in 2011 when two tremors, one of magnitude 2.3, hit the Fylde
coast in Lancashire on the 1
st
April followed by a second of magnitude 1.4 on
the 27
th
May.
Following investigation by the British Geographical Survey, the epicentre
for each earthquake was identified as about 500 metres away from the Preese
Hall 1 well at Weeton, Blackpool following hydraulic fracturing.
The geo-mechanical study of the Bowland Shale Seismicity report carried
out by independent experts said that the combination of geological factors
that caused the quakes was rare and would be unlikely to occur together
again at future well sites.
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There was no damage as a result of the two earthquakes and the report
stated ''If these factors were to combine again in the future, local geology
limits seismic activity events to around a magnitude 3 on the Richter scale as
a worst-case scenario''. To put this into context, an earthquake of magnitude
2.5 or less is usually not felt but can be recorded by a seismograph, while
earthquakes of magnitude 2.5 to 5.4 are often felt but only cause minor
damage. Dr Cliff Frohlich of the University of Texas at Austin carried out a
study of the correlation between injection wells and small earthquakes and
he commented that there is a question of what kind of damage that a
magnitude 3 earthquake could do to drilling infrastructure. ''It's plausible
