Although there are still thought to be around 20 billion barrels of the black stuff under the waters off Aberdeen, extracting it is getting ever more difficult and costly.

尽管仍然有人认为在阿伯丁海岸的海底储存着大约200亿桶原油，但是提炼它却更加困难，成本更高。

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They believe that roughly a third of the oil and gas potential under UK waters still remains to be extracted.

BBC: Study predicts growth in oil and gas field numbers