During Hydraulic fracturing, fracturing fluid is released at high pressure into the rock formation to create millimetre-sized cracks.
Before hydraulic fracturing takes place, the EA must approve the proposed composition of Cuadrilla’s fracturing fluid, which along with fresh water and sand includes:
- Polyacrylamide friction reducer
- Hydrochloric acid
- Sodium salt
None of Cuadrilla’s fracturing fluid contains hazardous or toxic components.
So far, Cuadrilla has only used a friction reducer along with a miniscule amount of salt, which acts as a tracer.
Before Cuadrilla began hydraulic fracturing, we disclosed the potential fracturing fluid composition on our website. After hydraulic fracturing began, we posted on the website the full details of the fluid we had actually used.
While the maximum number of additives and their concentrations are listed, Cuadrilla has only used a friction reducer during fracturing at Weeton along with a miniscule amount of salt, which acts as a tracer.
During the fracturing process, additives may be used to decrease the pressure required to pump into the well, to kill bacteria in the water, and to identify the water used during different fracturing treatments.
Click here to view the overall composition of our fracturing fluid used in 2011.
In all of our hydraulic fractures so far, polyacrylamide has been used to reduce friction between water and the pipe wall which allows us to reduce the pressure required during fracturing. As you can see from the chart, this friction reducing additive makes up 0.04% of the fracturing fluid – translating to 3.7 meters3 used at our Preese Hall 1 well.
Polyacrylamide is not a hazardous or toxic substance. Uses include:
- A flocculant (removal of suspended solids) in drinking and wastewater plants
- Soil remediation
Between 20-40% of the water used during the fracturing process flows back to the surface – this is known as ‘flowback water’.
The rest remains underground, though much of it returns to the surface, up the bore with the gas, over the lifetime of the well.
The flowback water is tested as it comes to surface (both by the Environment Agency and Cuadrilla) and is treated and disposed of according to Environment Agency rules.
When Cuadrilla’s fracturing fluid– consisting of ordinary water, sand and one chemical – returns to the surface it can contain very low levels of “naturally occurring radioactive materials” (NORM) – such as those found around the UK at surface outcrops of granite and shale rock.
Cuadrilla routinely applies for a range of permits as part of the on-going regulation of our business. New European regulations which came in to force on 1st October 2011, specified in Schedule 23 of the Environmental Permitting Regulations 2010, require a new permit for water disposal. We plan to apply for this new permit in due course.
To find out more about flowback water and regulation, please click here to visit the Environment Agency’s recent report.