By REBECCA SHEARER
An independent study conducted by the British Geological Survey (BGS) shows that there are substantial amounts of oil and gas available in Scotland’s Midland valley – around 80 trillion cubic feet of gas alongside 6 billion barrels of oil – in the Midland Valley of Scotland, the geological term for the Central Belt.
This BGS shows the topographical extent of the greatest shale oil and gas reserves in Scotland – which are also the fields most likely to be commercially recoverable (see map, at foot).
The shale oil field includes the ‘Gullane Gulf’ – extending from Glenrothes in the north, across the Forth estuary to landfall at East Lothian – around Gullane, Musselburgh and Tranent – and then extending south into Midlothian around Dalkeith and near to Penicuik.
There is another shale oil ‘hotspot’ around Alloa and Kincardine to the west – while the shale gas field includes both these areas as well as much of West Lothian – where shale oil mining first began in Scotland in the 19th century – and extending into eastern Glasgow and the Lanarkshire towns of Motherwell and Hamilton.
Not surprisingly – in geological terms – they are also very similar to the locations of the now extinct Scottish coal mining industry.
While geoscientists from the BGS have reviewed the geology and estimated the in-place resources for the volume of shale gas and oil in the ground, reserve and recovery estimation is not possible at this stage.
In order to estimate the shale gas and oil reserves, drilling and testing of new wells will be required to understand if commercial production rates could be achieved.
The results of the analysis show resources of shale gas and shale oil in place. The range of total in-place oil resources for the Carboniferous shale is 3.2 – 6.0 – 11.2 billion bbl (421-793-1497 million tonnes) and range of total in-place gas estimate is 49.4 – 80.3 – 134.6 tcf (1.40 – 2.27 – 3.81 tcm).
It should be noted that these ‘oil-in-place’ and ‘gas-in-place’ figures refer to an estimate for the entire volumes of hydrocarbons contained in the rock formation, the resource, not how much can be recovered. This methodology is similar to that used in the resource assessment for the previous BGS reports of the Bowland and Weald shales, but the uncertainty in the Midland Valley of Scotland is compounded as there are fewer historic wells and seismic lines to provide data. A BGS spokesman said:
“Without substantive data from drilling and production rates, figures for reserves cannot be reliably estimated. In time, the drilling and testing of new wells in the Midland Valley of Scotland will give an understanding of achievable, sustained production rates.
“The Scottish carboniferous shales are mature for oil generation from shallow burial depths of a few hundred metres or less over parts of the MVS study area, and gas-mature shales occur at depths from about 2,300 ft below the surface.
“These are shallow maturity depths when compared to those of the Bowland shale, Jurassic shales of the Weald and many commercial plays in the USA, which adds to the uncertainties about production potential.”
The Midland Valley of Scotland has a long history of oil and gas exploration. The West Lothian Oil-Shale Formation was the birthplace of the oil-shale industry in the 1850s with over 100 oil-shale companies active by 1900 in extracting oil by heating the shale in retorts, where it outcrops at the surface. (Note that this is a completely different technology from oil or gas drilling, more akin to coal mining).
This is the third BGS survey of shale-bearing reserves in the UK.
The first study, published in June 2013, reviewed the Bowland-Hodder shales covering 11 counties in the North of England. The central scenario estimates there is likely to be some 40 trillion cubic metres (1,300 trillion cubic feet) of shale gas in the ground.
The second study of the Jurassic shale of the Weald Basin in southern England, published in May 2014 concluded that is unlikely to be any shale gas potential, but there could be shale oil resources in the range of 2.2-8.5 billion barrels of oil (290-1100 million tonnes) in the ground, reflecting uncertainty until further drilling is done. A reasonable central estimate is 4.4 billion barrels of oil (591 billion tonnes).
The UK Government is expected to announce the 14th onshore oil and gas licensing round imminently, in which 20,000 square km in Scotland could be offered for exploration and production licences. The Scottish Government last week tightened planning policy in relation to onshore unconventional gas extraction by imposing mandatory ‘buffer zones’ for shale gas operations.
While the new BGS findings are not expected to signal a 19th-century style California gold-rush, many Scots land owners – and estate agents – will now start to geologically asses – and re-value – their land with a view to maximising ‘compensation’ payments from shale mining companies once UK petroleum exploration licences are issued.
A spokesman for Friends of the Earth Scotland commented: “These estimates mean that the aount of recoverable shale gas in the central belt is likely to be extremely low, with BGS estimating that there is only around 5% of the resource found in Northern England.
“The Scottish report also indicated a potential shale oil resource of 6 billion barrels. Only a very small proportion would be economically extractable so any production in Scotland would be trivial compared to the official estimate for recoverable oil in North Sea of 24 billion barrels.”