杏吧原创

The UK鈥檚 new oil rush may have ended before it even began. There are several billion barrels of oil under south-east England, according to a new report, but it may not be worth drilling for it.

The , by the British Geological Survey, estimates that there are trapped in the shale rocks of the Weald Basin, south of London. However, it concludes there are no significant gas deposits in the area.

Energy companies will have to resort to the controversial technology of fracking to get at the oil. But they may decide not to bother, says petroleum geologist of Durham University in the UK. That鈥檚 because very little of the oil can be reached, even with fracking.

Inconvenient numbers

鈥淟ooking at data from the US, the exploitable amount of oil from fracking is normally around 5 per cent of the total reserve,鈥� Aplin says. This suggests only 110 to 428 million barrels of oil could be extracted from south-east England.

Even that might be optimistic. The 5 per cent figure comes from areas rich in limestone. In clay areas, like the Weald, the figure is lower. What鈥檚 more, the oil in the Weald comes from similar rocks to North Sea oil, which is heavy and viscous. If Weald oil is the same, extraction will be difficult.

So Aplin estimates that only 1 per cent of the total reserve in the Weald 鈥� 22 to 86 million barrels 鈥� can be extracted.

鈥淏ritain consumes about half a billion barrels of oil per year, so if only 1 per cent is extractable that would be about two months鈥� consumption,鈥� says Aplin. 鈥淚t doesn鈥檛 seem like a very big prize to me.鈥�

Fracked

Northern England looks more promising. An earlier BGS survey , perhaps 37.7 trillion cubic metres. There are also deposits in the south-west. In theory, this is enough to meet the UK鈥檚 gas needs for 40 years, but the US experience suggests that only 10 per cent can be extracted.

鈥淪o you鈥檙e talking about only a few years of potential UK consumption,鈥� says Aplin. 鈥淭hat鈥檚 not to sniff at, but it doesn鈥檛 change the basic message that we as a country will be continuing to import oil and gas in future.鈥�

US fracking also suffered a blow this week. New figures suggest California鈥檚 Monterey Shale holds just 600 million barrels of oil,.

That may be because California鈥檚 rocks are heavily fractured, so large, undisturbed oil deposits are less likely to be found, says Aplin.