There is a lot of hot air spoken about fracking, but let’s take a cool look at some of the facts.
Traditionally oil and gas have been extracted from porous rocks like sandstone, but shale gas is different. The gas is trapped in microscopic pores or adsorbed in organic matter in hard shale and can only be released if the rock is fractured. Hence the need for hydraulic fracturing, or ‘fracking’ as it is usually known.
The idea is to drill vertical boreholes a mile or more deep then turn sideways to drill horizontally into gas-bearing shale beds. (Yes, it’s possible to drill round corners!)
A steel lining tube is cemented in place then a wire equipped with explosive charges is pushed to the far end of the hole. The detonated charges punch holes in the lining and crack the adjacent rock. Fracking fluid is then pumped into the hole under pressure to open up the cracks and allow gas to seep out when the fluid is pumped out.
Fracking is not new. It was introduced in the 1860s in the USA, at first for oil and then for water and gas production, and has been widely used from the 1970s. Today there are over two million fracked holes worldwide, not only to recover shale gas but for improved recovery of oil, groundwater and geothermal heat.
There are already over 200 fracked holes onshore in the UK – and many more offshore.
In the UK the most promising source of shale gas is the Bowland Shale, found at depth in a broad stripe across England from Lancashire and Cheshire in the west to the East Riding and Lincolnshire in the east. Much of the area is rural but the shale is also found below towns and cities from Liverpool and Manchester to York and Hull.
So how much shale gas is there? Estimates vary widely and have been lowered in recent years but the Upper Bowland Shale alone is conservatively estimated to contain 28 trillion cubic feet of recoverable gas, enough to meet Britain’s needs for over ten years at present rates of consumption.
So why aren’t we exploiting it? Despite what alarmists say, fracking is very safe.
But surely, they say, fracking causes earthquakes! Well minor tremors, yes. But are they damaging? No. The cracking of rock during fracking causes micro tremors, most detectable only by sensitive instruments.
The maximum tremor recorded during test drilling near Blackpool in 2019 was magnitude 2.9 but was felt by few and caused no damage, but it breached the government’s absurdly low and arbitrary limit of magnitude 0.5, bringing all shale gas exploration to a halt.
By comparison the Dudley Earthquake of 2002 was magnitude 4.8. It rattled tiles and shook windows but caused no structural damage. It should be noted that each magnitude on the Richter ML scale is 10 times greater than the one before, so Magnitude 4.5 is 10,000 times greater than 0.5 and Magnitude 4.8 is nearly 20,000 times greater.
It is often claimed that fracking can release gas into the water supply, but of the millions of holes fracked there has been only one supposedly clear example, in Wyoming, of fracking having caused groundwater to be contaminated with gas and chemicals. However naturally occurring methane is actually quite common in groundwater in Britain.
But what about contamination of groundwater with chemicals? Well, the fracking fluid itself is over 95 percent water, plus a few percent of fine sand to keep the cracks open and a dash of additives to reduce friction, kill bacteria and prevent corrosion. The additives are the same as found in common household products, such as acetic acid, starch, and enzymes, so fairly benign. Besides which the fracking fluid would have to migrate upward through a mile or more of solid rock in order to reach shallow groundwater, something that just doesn’t happen.
And drilling for shale gas does not wreck the countryside. The surface set-up to drill a series of boreholes is no larger than a football pitch, and when completed the site can be returned to its original condition, leaving only pipework at the top of each well about the size of a telephone kiosk.
The downside: drilling and fracking requires a lot of water – up to two million gallons per hole although much can be re-used. However the waste water needs to be disposed of. A potential problem is that it contains some natural salty water from the deep rocks that is slightly radioactive, but with appropriate treatment that can be overcome.
Despite the rush to net zero, Britain needs secure supplies of natural gas and will do so for some decades to come. Now is the time to push on with exploiting our own shale gas resources and ignore scare stories about fracking.