About 6 Bbbl of oil and 2 Tcm (71 Tcf) of gas could be trapped in Carboniferous shale buried beneath Scotland, but it is uncertain how much of these resources are technically recoverable given complex geology and limited good quality seismic and well data, according to a report released by the British Geological Survey (BGS).

The report, unveiled June 30, examined the geology of the Midland Valley of Scotland, which the BGS described as being fault-bounded by the trending Late Palaeozoic sedimentary basin, Caledonide Highland Boundary Fault and the Southern Upland Fault.

Prospective shale oil and gas could lie below an area that stretches from Glasgow to Edinburgh to the Lothians, Falkirk, Clackmannan and Fife. The play can be considered stacked like some shale plays in the U.S. such as the Spraberry and Wolfcamp plays, according to the report. The BGS pointed out that while it did not examine the hybrid conventional, tight oil and tight gas potential of the play, “evidence of numerous oil and gas shows in wells suggests that tight oil/gas could be a complementary resource in the Midland Valley of Scotland.”

“The potentially prospective Midland Valley of Scotland succession is up to 9,800 ft [3 km] thick and contains numerous shale-rich intervals within a vertically and laterally heterogeneous sequence,” the report said. “Shale beds vary in thickness from a few inches to around 160 ft [50 m] and are interbedded with numerous lithologies including sandstone, limestone and coal, as well as igneous rocks.”

Unlike the U.K.’s Bowland-Hodder and Jurassic shales of the Weald as well as many commercial plays in the U.S., the report said that the oil- and gas-mature depths of the Midland Valley shales are shallow.

However, the BGS believes the Scotland shale play could hold at least an estimated 1.40 Tcm (49 Tcf) of shale gas in-place and 3.2 Bbbl. High-end estimates put the total gas in-place at 3.81 Tcm (135 Tcf) and 11.2 Bbbl for oil in-place.

“In time, the drilling, fracturing and testing of shale wells will demonstrate if commercially viable production rates can be achieved,” BGS said in the report. “These, combined with other nongeological factors, such as engineering design, operating costs and the scale of development agreed by the local planning system, will allow estimates of the U.K.’s producible shale oil and shale gas reserves to be made in the future.”

The estimates were welcomed by the industry groups, including the U.K. Onshore Operators Group (UKOOG).

“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 U.K.’s growing dependency on imports and balance the decline of the North Sea,” Ken Cronin, CEO of UKOOG, said in a prepared statement. “The oil and gas industry has been operating in Scotland since the 19th century and looks forward to continuing to operate safely and with the minimum of environmental impact for many decades to come.”

The report was the third conducted by the BGS on potential U.K. shale oil and gas resources. The other two, which covered larger study areas, concentrated on the Bowland-Hodder and Weald Basin.

In the Weald study, the BGS estimated a range of shale oil in-place of between 2.0 Bbbl to 8.57 Bbbl with no significant gas resources yet. In the Bowland-Hodder shale gas study, gas estimates ranged from 25 Tcm (822 Tcf) to 68 Tcm (2,281 Tcf).

Professor Mike Stephenson, director of science and technology at the BGS, said “the Midland Valley of Scotland has complex geology and a relative lack of data compared to the previous DECC-BGS Bowland-Hodder and Weald Basin studies.”

The studies further boost efforts to develop shale resources in the U.K., where the latest measure includes allowing license holders to retain bigger areas and cut costs. But opposition, mainly concerning the use of hydraulic fracturing, still exists in the region.

In response to the Scotland shale report, U.K. Business and Energy Minister Michael Fallon said, “Making the most of Britain’s home grown energy is crucial to keep job and business opportunities, widen tax revenues and reduce our reliance on foreign imports. We know that shale gas alone won’t be able to supply all of our energy needs, but the environmentally responsible exploration of shale gas could contribute to our energy mix.”

Contact the author, Velda Addison, at vaddison@hartenergy.com.