The NLS's CAIRT newsletter has a link to a website on the shale oil industry.

The story of Scotland's shale oil industry

http://www.scottishshale.co.uk/ 

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A few more refs:

No More Bings in Benarty. Published by the Benarty Mining Heritage Group. 1992 £5 pf on Ebay 20.08.07. Account of the rise and fall of coal mining in Benarty hill area , how it influenced people’s lives, interesting look at social history of good people

Geikie, Sir Archibald 1900 The Geology of Central and Western Fife and Kinross. Glasgow, HMSO. 206-206 Oil-Shale.

Kerr, David 1999 2nd revised edition. Shale Oil Scotland . The World’s Pioneering Oil Industry 158 illus. Not read

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As you'll read, there was an allied shale oil industry in NE Wales around Pontblyddyn, Leeswood and Padeswood, in the Alyn Valley south of Mold. There are significant cannel coal seams that were mined until the 1990's (Coed Talon drift mine) although the oil industry itself died by the 1890's. If I was to dig a 50ft shaft in my back garden, I'd hit the cannel beneath Treuddyn. But mineral rights don't belong to me according to our deeds of 1844...

Mold in the mid 1800's through to the 1930's could be quite riotous with the local lead miners - Halkyn Mountain and Alyn Valley vs the coal miners of Mold, lower Alyn Valley (Leeswood, Coed Talon and Treuddyn) 😮

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North Wales cannel coal was a much richer source of oil than oil shales. In the mid C19, North Wales cannel coal commanded the highest price per ton of any UK coals - often over 30 shillings a ton compared to 10 to 15 shillings a ton for regular coals, and low 20s for prime steam coals. Cannel coal's value was reflected in the extent to which it was worked - the reserves were largely worked to exhaustion.

North Wales cannel coals (and the oil shales that overlie the cannels) are geologically significantly younger than the Scottish oil shales.

Scottish oil shales occur between the Old Red Sandstone and the Carboniferous Limestone. North Wales cannels occur within the Coal Measures and the oil shales overlie the cannels.

Scottish shale oil yields were generally somewhat lower than that obtained from North Wales oil shales - typically 20 to 30 gallons per ton compared to an average of 33 gallons a ton. North Wales cannel coal could contain much more - it ranged from 35 to 80 gallons a ton.

Both the North Wales cannel coal mining industry and the North Wales oil shale mining industry are much less well known than the larger Scottish oil shale mining industry. This is partly because the North Wales industry largely exhausted its reserves and declined half a century before the Scottish oil shale industry wound down.

It could have been different though - in the late 1930s there were proposals to mine millions of tons of North Wales oil shale and to build a modern refinery to process it. One of the great 'might-have-beens' of Welsh mining history...

There's a postscript for N Wales...

IIRC, around 1979/80, a coal to oil pilot plant was built at Point of Ayr colliery. It worked but then the price of oil dropped again and soon after, the colliery itself was closed down. The coal seams there were very gassy and they were bored into well ahead of the working face and exhausters extracted the gas and sent it up to grass where it was scrubbed and exported into the UK's gas grid.

Ironically, the site of the colliery is now the shoreside terminal for the gas and condensate coming from the Liverpool Bay gas fields where the gas and condesate is separated. The gas (sour) is exported to Connah's Quay Power Station where the gas is cleaned - some for power station use, the majority into the gas grid...

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