Controversy over UK shale
New research suggests that UK shale gas reserves could be exhausted in less than 10 years – far lower than previously thought. Ceri Jones finds out more.
The UK has around seven to 10 years worth of shale gas reserves, according to a 16-year study carried out by the University of Nottingham and the British Geological Society (BGS). Initial data released in 2013 estimated the UK to have one of the largest shale reserves in the world, with 1,300 trillion cubic feet of shale gas.
As economic recovery is widely agreed to be 10% of the total, then Prime Minister David Cameron announced that, ‘even if we extract just a tenth of that figure, that is still the equivalent of 51 years’ gas supply.’ However, the new paper scaled that figure down to less than 10 years at current demand, provoking severe criticism from the oil and gas industry, as well as other scientists.
What has changed?
With the UK having no production data to build upon, the previous study involved a desktop analysis of shale resource, not reserves, from the USA. Author of the recent paper, Shale gas reserve evaluation by laboratory pyrolysis and gas holding capacity consistent with field data, University of Nottingham Professor, Colin Snape, told Materials World that the new method set out to record more realistic estimates of the gas in place than in 2013.
The team ran a series of lab-based tests on UK shale rock samples, including some sourced from the Bowland shale formation in north England. Rock pore sizes were measured to determine the proportion of large pores holding free gas, as well as micro pores that require hydraulic fracturing. Adsorbed plus free gas from pore spaces was recorded, and in-lab high-pressure water pyrolysis used to account for the oil expelled by the shale. Results were extrapolated for the whole basin, and estimated it to hold 20 trillion cubic feet of recoverable gas.
It’s a gas
Snape told Materials World the difference in results comes from many factors, primarily the use of in-lab testing over theoretical, and UK shale being so different to that found in the USA. The team selected high quality rock samples to test, but Snape said as the uniformity varies greatly across the reserve, and UK shale being of far lower quality than in the USA, these results present a best case scenario.
In addition to a lower gas volume, Snape referred to 2017 research by geologists at Scotland’s Heriot-Watt University Institute of Petroleum Engineering, which stated that tectonic plate shifts were unfavourable for UK fracking, as they enabled gas to escape to the surface. As Snape said, even if you identify what should be a free gas hot spot, you could start drilling and find nothing.
Scepticism of the results was inevitable, but there has also been doubt from within BGS with several people, including Chief Scientist for Decarbonisation and Resource Management, Professor Mike Stephenson, calling for caution due to the small sample range from only two locations.
Industry representative body, UK Onshore Oil and Gas (UKOOG) echoed this, and stated that its continuous 3D seismic surveying, drilling, fracking and flow testing processes are more reliable than the study.
‘Nottingham in their research have analysed a limited amount of core from one Bowland shale well drilled in 2011, which was subsequently decommissioned without hydraulic fracturing or flow testing,’ UKOOG CEO, Ken Cronin, said. He added that UKOOG disagrees with the ‘generalisations and assumptions used by the authors of this research regarding the uniformity, nature and quality of the rocks and reservoirs’.
While Snape said the study’s results correlate with those published by gas production firm Cuadrilla earlier this year, suggesting accuracy, Cuadrilla was quick to criticise. ‘Those involved in publishing this should be embarrassed. We hold more data and technical experience of the Bowland shale than anyone else in the UK, yet not once did anyone from this research group or Nottingham University contact us for our view or input,’ said CEO Francis Egan.
‘We will continue the current operational programme to fracture the remaining stages of PNR2 well and then we will be flow-testing it. Then let’s make some statements about the reserve potential of the Bowland Shale,’ he added.
Snape countered criticism and said the paper ‘can only serve to improve people’s understanding and government decisions around the future of what role shale gas can make to the UK energy’s demand as we move to being carbon neutral by 2050’.
Read the paper, published in Nature Communications, here: go.nature.com/2lKTGB3