Guest post by Kathryn McWhirter
Tomorrow (11 January 2017), North Lincolnshire Council is expected to decide on a plans for oil production at Egdon’s site at Wressle, near Scunthorpe.
The application includes proposals for the little-discussed process of acidisation.
In this Guest Post, writer and campaigner Kathryn McWhirter investigates the use of acid in the onshore oil and gas industry.
The first part of her post is an introduction to the process. If you want to read more, Kathryn McWhirter has made a detailed study based on scientific papers, industry training manuals, promotional literature for new, patented technologies, and discussions with engineers, geologists and scientists.
It’s time to talk about acid
Finally, we’re all talking about shale gas and fracking.
And we are ignoring the threat quietly posed by other extreme forms of gas and oil exploration. It’s time to broaden the discussion, and talk also about acidising, or acidisation.
Acidising, little understood outside the oil and gas industry, is coming to communities from Sussex and Surrey to Lincolnshire. Acidising poses its own threats, and is likely to lead on to fracking at a later stage.
Planners and councillors are already facing decisions on applications for acidisation, yet they don’t, for the most part, understand the science and the risks, nor the likelihood of proliferation – the very large number of wells that could be drilled.
The oil and gas industry seems to do its best to confuse, using obscure wording in planning applications. Planning applications may not mention acidising by name. ‘Well stimulation’ sounds relatively friendly. The application at Markwells Wood in Sussex by UK Oil and Gas Investments plc calls it:
‘a new non-massive fracking-based reservoir stimulation technology that does not involve massive hydraulic fracturing’.
Few studies have addressed the potential problems. In the UK there is little regulation or oversight.
Fracking is for shale. Acids are used to dissolve unyielding limestone or sandstone to make pathways for oil or gas flow. It’s not new. But like fracking, acidisation is now planned on a far bigger scale, down long, horizontal wells, a great multiplicity of wells. Many co-additives are needed to make the acids work effectively – a greater concentration of chemicals than are used in fracking fluids for shale.
Acids in question range from hydrochloric (for limestone) to the super-dangerous hydrofluoric (for sandstone). Acidising can be done at low pressure, or, like fracking shale, at major pressure that fractures rock. Not so long ago this would have been called an ‘acid frack’, but the government re-defined fracking in 2015 on the basis of the amount of fluid used rather than rock-cracking pressure.
If it’s not officially fracking, none of the new rules and regulations developed by government under oil and gas industry guidance will apply – so oil companies will feel free to drill and acidise in National Parks, Sites of Special Scientific Interest, Areas of Outstanding Natural Beauty and so on, at depths of less than 1,000 metres, without any of the baseline monitoring prescribed for fracking.
‘Acid fracking’ is not the only expression government and industry are keen to avoid in their attempt to make this extreme form of oil and gas extraction a non-issue for public, planners and press.
Conventional versus unconventional
There is also a game of words around the terms ‘conventional’ and ‘unconventional’. There are no statutory definitions for these terms. Geologists and engineers use the term ‘conventional’ to describe a geological formation from which oil or gas flows easily. ‘Conventional’ formations are permeable, so that one well can drain the rocks over a wide area.
In ‘unconventional’ formations, the oil or gas remains trapped in minute globules in the rock until ‘stimulated’ or released, by fracking, acidising or other means. ‘Unconventional’ formations are also known as ‘tight’ formations. At Balcombe and Horse Hill, for example, in Sussex and Surrey, the micrite limestone is ‘tight’ and ‘unconventional’.
Yet the government declared all the PEDLs across the Weald to be ‘conventional’ when the announcement of the 14th round of new petroleum exploration and development licences was buried in the Christmas wrapping paper of 2015. Meanwhile, oil and gas companies call their ‘prospects’ in the Weald ‘unconventional’ when talking to potential shareholders, but imply that they are ‘conventional’ when speaking to local communities.
Arguments against acidisation
Most of the negative arguments against fracking can also be made against acidisation – plus many more for ‘stimulation’ with hydrofluoric acid, one of the earth’s most dangerous chemicals.
UKOG CEO Stephen Sanderson has explained to shareholders that acidised wells would, like high-volume hydraulically fracked wells, need to be ‘back to back’ at regular intervals across the Weald to access as much as possible of the oil – since the oil will flow only from the ‘stimulated’ parts of the rock near the wellbore. This proliferation of wells, industrialisation of the countryside, is one of the main reasons to oppose unconventional drilling.
As with fracking for shale gas, there are questions over human and animal health, environment and climate.
Chemical use is even greater in acidisation than in hydraulic fracking. Solid and liquid waste will be toxic, highly saline and radioactive, a risk to groundwater, surface water and soil should accidents occur.
There will be potential air pollution from flares, potential groundwater pollution via faults, fractures and the well bore, noise and light pollution, traffic, the risk of spills and other accidents. Storm and floodwater may spread pollution. Wells may be acidised repeatedly. There is little research on the subject of repeated acidisation and the cumulative effect on our environment and human health. On-site workers and local communities are particularly at risk. Significantly, Portsmouth Water, the CPRE and the local Environment Agency objected to UKOG’s application to drill and acidise at Markwells Wood, West Sussex.
Fracking seemed enough to get our heads around. But the general public, campaigners, planners, water companies, politicians and regulators now all need to put acid on their agenda.
They should also think critically ahead and understand that, although initial planning applications may seek to acidise at below fracturing pressure, production stage will almost certainly require acidisation at pressure sufficient to fracture the rock.
To find out more, Kathryn McWhirter has carried out a detailed study of acidising. It is based on scientific papers, industry training manuals, promotional literature for new, patented technologies, and discussions with engineers, geologists and scientists.
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