No shale bounty for Scotland
SCOTLAND could have sizeable unconventional oil and gas reserves, but they’re unlikely to match the resources held by England, the British Geological Survey (BGS) concluded. A recent survey carried out by the BGS
said the Midland Valley in Scotland could hold between 49.4 trillion cubic feet (cf) and 134.6 trillion cf of shale gas. The mid-estimate for the resource is 80.3 trillion cf.
The range for estimated shale oil-in-place is between 3.2 billion barrels and 11.2 billion barrels, the report said, with a central estimate of 6 billion barrels.
Scotland’s Midland Valley lies beneath the country’s Central Belt, running from from Girvan to Greenock in the west, and Dunbar to Stonehaven in the east.
The BGS emphasised that the figures were not estimates of shale oil and shale gas potential, but were instead of “potential where shale-bearing rocks” could be.
However, the BGS said that because of the complex geology and limited amount of good-quality data available for the Midland Valley there was a high degree of uncertainty about whether the estimates were accurate.
The BGS said that the Midland Valley shale intervals occur within a stacked rock sequence and individual shales are thinner than in many other unconventional gas and oil systems across the globe.
The report added that it is not yet possible to estimate how much shale gas or shale oil could commercially recoverable. “Shale gas and oil clearly has potential in Britain, but it will require geological and engineering expertise, investment and protection of the environment,” the BGS said in a statement. “It will also need organisations like the BGS to play their part in providing up-to-date and accurate information on resources and the environment to the public, industry and government.”
The BGS said that potentially prospective carboniferous shales are buried beneath an area from Glasgow to Edinburgh, to the Lothians, Falkirk, Clackmannan and Fife.
There are four areas thought to be prospective for shale gas and shale oil: the Limestone Coal formation, Lower Limestone formation, West Lothian oil-shale unit and the Gullane unit. The BGS said abandoned coal mine sites are present over some of the prospective areas.
The BGS pointed out that the oil and gas-mature depths of the Midland Valley shales are shallow compared with the Bowland-Hodder shales, Jurassic shales of the Weald and many commercial plays in the US. The Midland’s shales are up to 3,000 metres thick with individual shale units varying in thickness from centimetres to 50 metres.
The UK Onshore Operators Group (UKOOG), the representative body for the UK onshore oil and gas industry, welcomed the report, saying it gave assurance to Scotland’s would-be investors and could enhance UK energy security. “This report will give reassurance to investors who wish to explore for oil and gas onshore in Scotland and adds to the estimates of significant onshore resources which can help replace the UK’s growing dependency on imports and balance the decline of the North Sea,” Ken Cronin, chief executive of UKOOG, said.
The BGS’ latest figures for shale oil and gas potential in Scotland follow studies pointing to vast unconventional energy resources in England. However, the UK government said the BGS’s report on the Midland Valley resources suggests only “a modest amount of gas and oil in place” compared to estimates for England’s unconventional resources.
Last year, the BGS released long-awaited estimates for shale gas and shale oil in place in northern England’s Bowland basin. The study said total gas-in-place figures for the Bowland range from a low-end estimate of 822 trillion cf to 2,281 trillion cf on the high end. The central estimate for gas-in-place in the basin is 1,329 trillion cf.
In June this year, the BGS said southern England’s Weald basin could hold almost 9 billion barrels of shale oil which, if proved up, has the potential to triple the country's crude reserves.
The government added that the amount of oil or gas which would be commercially extracted in the Midland Valley “is expected to be substantially lower” than the total amount of gas and oil in place. It also stressed that the numbers were highly uncertain because, in comparison to previous study areas, fewer wells have been drilled in the play and there is less seismic data available.
Michael Fallon, the UK business and energy minister, said shale oil and gas could help to enhance UK energy security but “only the broad shoulders of the United Kingdom” could attract the investment needed.
Scotland is due to hold a referendum on independence in September. The division of the UK’s North Sea oil and gas reserves is a key battleground for supporters and opponents of a referendum.