Don’t bank on shale

SIR – Gas and energy supply are crucial for the United Kingdom, especially during times of heavy demand due to severe weather. Now that we rely on imports for more than 50 per cent of our needs, there is a suggestion that shale gas can ride to the rescue.

Ambrose Evans-pritchard (Business, March 28) perpetuates that argument by accepting Cuadrilla’s statement at face value. However, one vertical well does not make a shale gas province.

Until such time as a multi-stage hydraulic fracture flows gas from a horizontal well, the viability of shale gas remains untested in the UK.

US examples have demonstrated that shale gas success is not predicated on thickness, but on factors including organic richness, brittle source rocks, the simplicity of geological structure to position the horizontal wells and the overpressure to help them produce.

In contrast, the geology of the Lower Carboniferous shale target in the Bowland Basin is highly complex and lacks overpressure, due to the area’s exhumation 55 million years ago.

As a result, any production is likely to be focused on small, local areas where the key geological criteria are met.

Consequently, Britain’s shale gas resource estimates remain inflated and the “bonanza” remains highly speculative.

Given the geological uncertainty, it would be foolhardy to assume that shale gas will work on the industrial scale needed. Alternative solutions should continue to be sought for the gas that heats 80 per cent of our homes and provides 25 per cent of our electricity. Professor John Underhill

Chief Scientist Heriot-watt University, Edinburgh