23rd May 2014
There could be up to 8 billion barrels of oil under the Weald in southern England, according to a report out today. But it may be difficult to extract – and there’s unlikely to be any shale gas.
The long-awaited report by the British Geological Survey (BGS), published this morning, studied an area from Ashford in Kent to Salisbury in Wiltshire.
It concluded the “Weald Basin shale oil has the potential to add to the country’s resource base”. It said a “reasonable central estimate” of the volume in the ground was 4.4bn barrels, with a top estimate of 8.5bn barrels of oil. (To put this in context, oil production from the North Sea amounted to 45 billion barrels over the past 40 years.)
But there’s no guarantee the Weald shale oil could be recoverable. The organisation’s Professor Robert Gatliff told a news conference the Weald could prove to be a “difficult play” for the fracking industry.
According to the report, the Weald shales do not meet many of the criteria for a successful shale oil play, or there is no data to make an assessment. The report says they may contain less oil than similar formations in north America and the rock may be more difficult to frack.
The report also says the shale should preferably be in large stable basins without complex tectonics and “wells should be drilled away from faults where possible”. But in the Weald the basin is “generally small” and “faulting locally occurs at high densities”.
The BGS says it can’t make a reliable estimate of how much shale oil could be recovered from the Weald.
But Shale expert, Professor Andrew Aplin, of Durham University, said: “We might estimate that 1% of the Weald oil resource might be recoverable.” This would equate to 0.05 billion barrels, which is about two months of UK consumption, he said. “From a national perspective, this seems to be a rather small prize.”
The report added there was “unlikely to be any shale gas potential” under the region. Shale gas has been widely promoted by the government as a “bridge fuel” which, it says, would help Britain transfer to a zero-carbon energy system.
The energy minister, Michael Fallon, denied he was disappointed. “It is not a let-down or a let-up … I am not disappointed or happy. It is what it is.” Asked if shale had been overhyped, he said: “Not by the government.”
The BGS said the best chance of finding oil is in the centre of the region. It identified the Kimmeridge Clay and Oxford Clay as having the most potential. They cover an area from Lipook in Hampshire to East Grinstead in West Sussex, with Oxford Clay extending further east to Tunbridge Wells and Haywards Heath. Cuadrilla’s oil exploration site at Balcombe is within this area, as are planned drilling sites at Fernhurst, Billingshurst and between Wisborough Green and Kirdford.
The area of greatest potential also includes parts of the South Downs National Park and two Areas of Outstanding Natural Beauty – the Surrey Hills and High Weald. Last month, the body representing Areas of Outstanding Natural Beauty recommended said the government should not sell future licences for oil and gas developments in AONBs. The South Downs National Park Authority said the same should apply to National Parks. However, much of the area with the largest potential oil resources in the Weald is already licenced, mainly to Cuadrilla, Celtique Energie, Magellan and IGas.
- Cuadrilla’s well at Balcombe and an earlier well tested by Conoco are drilled into micrite, which is associated with Kimmeridge Clay. “The presence of oil within the mid-Kimmeridge I-micrite in Balcombe 1 is significant in that it may provide evidence for both maturity and the capacity of the Kimmeridge Clay to generate oil, at least locally”, the report said. But it added: “The oil discovered in Balcombe 1 and appraised by Cuadrilla with Balcombe 2 in 2013 is likely to constitute a conventional oil accumulation (probably in a structural closure or combination trap), albeit in a low-porosity limestone. Cuadrilla reported that the micrite at its Balcombe well was naturally fractured and would not require fracking.