But ageing fields, a difficult investment climate in Russia and a dearth of discoveries in other parts of the world means that in coming years, consumers will not be able to rely on countries outside Opec for additional oil.

• 但是各地油田面临老化，俄罗斯的投资环境困难，全球其它地区没有发现新油田，这都说明，在未来岁月里，消费者不能依赖欧佩克以外国家多产石油。