Dart Energy boreholes around Canonbie, Scotland
The Scottish Herald today reported the UK’s first fracking leak – at Coal Bed Methane (CBM) wells near Canonbie in Scotland. The leak – at wells owned by Dart Energy – confirm anecdotal evidence from locals who have – over the last two years – periodically noticed gas in their water supply.
The leak is of no surprise to the oil and gas industry – drillers know well that many of their gas wells leak. Research by oil services company Schlumberger suggests up to 60 percent of gas wells will be leaking within 30 years. The UK’s Society of Petroleum Engineers found 34% of gas wells leaking in the UK’s North Sea (document withdrawn? but referenced by Archer and SPE Production & Operations November 2013)
In the Norwegian North Sea 18% of gas wells are leaking. In 1992 the US EPA found 200,000 wells leaking, a 16.7% failure rate. There are many more studies and examples – see our piece on gas wells leaking.
The fracking industry has tried to divert attention from the issue of leaks. Dart Energy has denied plans to frack in Scotland, despite company documents clearly showing fracking depths, chemicals and pressures to be used at Canonbie. Yet the stark truth is that a sizeable proportion of all gas wells leak, whether onshore, offshore, conventional gas, shale gas, or CBM. It’s an industry-wide inevitability, and the reason many research papers, seminars and workshops are devoted to the issue. And unconventional gas means thousands of wells in highly populated areas, most of which are likely to leak eventually.
In Australia the CBM industry has produced hundreds of leaks – you can see what one looks like here:
The most common form of leakage is what the industry calls ‘sustained casing pressure’ (SCP) or ‘sustained annular pressure’ (SAP). This means that gas has leaked up the gaps between the well-casings to the surface. As the gas passes through any water aquifer present, it may escape into water supplies. Hence the famous footage showing flaming water taps in the US.
Professor Tony Ingraffea explains how leaks occur here:
For anyone involved in the fracking fight there are many certainties: the most compelling of which is that gas wells regularly leak. And in direct contradiction to politicians who claim the UK’s so-called ‘world-class regulation’ makes it somehow immune to the leaking problem, the situation at Canonbie proves just the opposite.
