Anyone who has been exposed to much of Cuadrilla Resources‘ public relations campaign to persuade people that what they are doing is not very bad is likely to have come across some sort of variant of there might have been a few problems in the US but we use three casings on our wells so there is no chance of any water contamination. Some examples of this include ‘Leakage of hydrocarbons or fracing fluid into shallow water aquifers through the walls of the drill shaft is prevented by the installation of three steel casings, each of which is cemented in place, in the zone of the shaft adjacent to and surrounding the shallow water aquifer’ in a submission by Cuadrilla to a parliamentary select committee in May and ‘Groundwater Protection: With our exploration well design we have 3 separate strings of casing cemented across the Sherwood Aquifer to prevent any possibility of contamination from well fluids or natural gas’ in publicity materials used by the company in Lancashire.
So what are well casings and what do these statements actually mean? Well casings consists of a series of metal tubes installed in the freshly drilled hole. They are usually but not always cemented into place. The purpose of well casings is to strengthen the sides of the hole and it provides a conduit to allow hydrocarbons to be extracted without intermingling with other fluids and formations found underground. There are usually several different casings that extend to different depths and are nested inside each other in a manner not dissimilar to an upside down telescopic radio aerial (see diagram below). The largest in diameter (around 20 inches) is the conductor casing which is usually only 20 to 50 feet deep and is installed prior to drilling proper commencing. It’s main function is to stop the top of the well from caving in. Inside this the surface casing will extend down up to 2000 feet and it’s main purpose is to protect fresh water deposits near the surface of the well from being contaminated. The production casing is installed last and is the deepest section of casing in a well. This is the casing that provides a conduit from the surface of the well to the petroleum-producing formation.
Schematic of Cuadrilla’s test wells provided to a parliamentary select committee.
In addition to those mentioned above, an intermediate casing (between the surface casing and the production casing) is also often installed. This is the third casing that Cuadrilla are talking about. It is interesting to take a look at what people have said about intermediate casings in the past (prior to the beginning of 2011). Descriptions like ‘intermediate casing (usually for much deeper wells), and it’s main purpose is to provide wellbore stability and a stronger casing string that will contain higher wellbore pressures’, ‘The primary purpose of intermediate casing is to minimize the hazards that come along with subsurface formations that may affect the well’, ‘An intermediate casing string may also be installed under certain conditions to isolate, stabilize or provide well control to a greater depth than that provided by the surface casing’, ‘In some deeper natural gas wells, intermediate casing is needed because some formations are encountered that contain abnormal pressures and/or conditions’ and ‘In addition to the conductor pipe, surface casing, and the oil string, an intermediate string of casing is often needed as a precautionary measure in nearly every deep well’ are typical. So the purpose of an intermediate casing is to protect the well from problems associated the rock formations it passes through and is almost always used in deep wells.
However if we turn to references to intermediate casing written in the last few months, the picture painted couldn’t be more different. References largely occur in conjunction with discussion of potential regulations that might be imposed by the New York state Department of Environmental Conservation (DEC) in return for lifting the fracking ban there. So for instance we find statements like ‘In most cases, an additional third, cemented well casing is required around each well to prevent the migration of gas. The three required casings are the surface casing, the new intermediate casing and the production casing.’ at the end of June or this ‘An additional, third cemented casing would also be required for each well to prevent gas migration. This casing would be an intermediate casing between the surface casing and the production casing.’
If this seems to you rather at odds with the descriptions we have read earlier, you aren’t the only one who thinks that. In fact it seems like even the people who are pushing this re-branding of intermediate well casings in the US, don’t really believe what they are saying. So apparently ‘A fact sheet provided by DEC acknowledges that in most cases the third casing already exists’. Given this it is not surprising that the industry are having a hard time persuading people who know about the subject that this is anything new. In the same news report from the end of August we read ‘“The vast majority of wells that show gas migration have intermediate casing already,” remarked Tony Ingraffea, a Cornell University professor of engineering at a presentation in Ithaca released by Shale Shock Media on August 1st.’
So there we have it, Cuadrilla’s main reasoning for why they aren’t going to contaminate water supplies in Lancashire is that they use a piece of equipment everyone uses on wells as deep as the ones they are drilling and which was present on most of the wells that have resulted in water contamination in the US. The purpose of this equipment also has very little to do trying to stop water contamination in any case. They don’t even get any points for originality since this “narrative” is actually a bunch of PR spin put together by the fracking industry in the US, in order to undermine support for a ban on fracking in New York state by re-branding something they are already using as a new safety measure. However this sort of behaviour fits right in with what we know about their other activities. Whether it is their use of the ownership of an old unrelated gas well in Lancashire to suggest that activities will not affect local communities or the fact that most of the documents on their website are written by a Tory councillor on the planning committee of Guildford District Council who is employed by a PR firm specialising in planning issues, Cuadrilla is all about spin.
