The world oil market has also learned to be disappointed with non-OPEC producers, as underinvestment and aging oil fields in places such as Mexico and Russia have crimped crude production.

• 一些非欧佩克成员的产油国也令石油市场失望不已，比如，墨西哥和俄罗斯等国投资不足以及油田老化的状况制约了原油产量。