The past 12 months give reason for scepticism. In December 2018 OPEC and its partners agreed to reduce output by 1.2m barrels a day.
Iraq, Nigeria and Russia, among others, have regularly exceeded their allowed limits.
To compensate, Saudi Arabia, OPEC's most powerful member,
slashed its own production by an average of 500,000 additional barrels a day, according to the International Energy Agency.
Analysts at Morgan Stanley estimate that in 2020 1.8m additional barrels a day will be pumped in countries outside the OPEC alliance,
including Brazil, Guyana and Norway. In the run-up to OPEC's meeting in Vienna in December,
it was doubtful whether the group would sustain the cuts agreed to a year earlier, let alone go further.
In the end Saudi Arabia's new oil minister, Abdulaziz bin Salman, wrangled an impressive deal.
最终，沙特阿拉伯新任能源部长Abdulaziz Bin Salman达成了一项令人印象深刻的协议。
The alliance's 1.2m-barrel cut will extend to 1.7m in January.
Additional reductions led by Saudi Arabia will push the total to 2.1m barrels a day.
The broader group's collective output will be 1.3% below its level in November.
It remains to be seen, however, if the cuts will materialise—or last. The new agreement covers only the first quarter of 2020.
It also allows Russia to increase its output of condensate, a type of light crude.
Saudi Arabia remains keen to support prices, both for its budget and to make Aramco's listing a success.
The firm's soaring valuation in early trading may not be sustainable.
Many big global investors were repelled by its low dividend yield, security risks and state control.
But local retail investors piled in, attracted partly by the sweetener of an extra free share for every ten they buy and hold for six months.
If Saudi Arabia's allies fail to stick to their promised cuts, the kingdom will have a choice: slash its own production further or let prices fall. Neither is appealing.