In the two weeks before the Gulf war started in January 1991, the oil price rose by $8 a barrel to $32. Six months before the war started, the price had been only half that, $16. Now, things are dramatically different. This week Brent Blend, the North Sea crude that serves as an international price bellwether, fell to its lowest point in nearly four years: $14.22. It has declined by a third since October.
Prices are so weak that many believe a US air offensive against Baghdad might add merely a dollar or so to the price, and even then it might only be a blip. Some fear the bottom may still not be in sight. So what has changed in the oil business? And how profound is the transformation?
This year's price fall began last November, when Saudi Arabia orchestrated a 10 per cent rise in Opec's production ceiling.
But the pressure on oil prices had been building for several months. In October the world produced three million barrels per day (b/d) more than in the same month in 1996.
There are four short-term explanations for this year's fall:
Asia: many Asian refiners, reeling from sharp falls in the value of their domestic currencies and preparing for an economic slowdown, stopped buying US dollar-denominated crude in the final quarter of last year.
The weather: the mild northern winter has cut demand for fuel oil and diesel used for heating. This week the gas oil (diesel) futures contract on London's International Petroleum Exchange hit an eight-year low. This has left stocks of crude oil at seasonally high levels.
Iraq: if there is a diplomatic settlement - or a post-bombing one - then Iraq's bottled-up exports might not just rise, but could more than double under a much-expanded oil-for-food proposal being debated this week in the UN Security Council.
New projects: last year, a range of one-off technical problems and a shortage of drilling rigs delayed many new projects in non-Opec countries.
All these factors help explain why prices are weak at the moment. But they do not capture the more profound transformation affecting the oil business.
For the oil price is not merely low compared with 1991. In real terms, it is only a little higher than at the first Opec oil shock in 1974. A comparison between that period and today is instructive.
Then, as now, there had been a long period of rising demand for oil on the back of strong world growth (last year, for instance, the US, the world's single biggest oil market, imported a record 10 million barrels of crude a day, a 7.2 per cent rise over 1996). Now, as then, Saudi Arabia thinks that importers do not appreciate the role it plays in the world economy: it alone has enough spare capacity to cushion the world against disruption in another large producer.
Then, a shift in the political tectonic plates of the Middle East made possible a dramatic price increase. Today, such a political shift would not be out of the question in the aftermath of air strikes against Iraq.
At first glance, these similarities might be used to suggest the world is passing through an artificial period of cheap oil that will be followed later by a substantial price hike. But against these similarities, there must be placed bigger differences.
In the 1970s, there was a perception that the world might run out of oil without having discovered an alternative fuel source. Over the past 20 years, technological advances have helped companies discover new fields and improve recovery rates, often at low costs. Hence the low breakeven point of the finds coming on stream this year.
It is true that the ratio of world oil reserves to current production now stands at only 40 years. But natural gas has emerged as an alternative to oil for many uses. Gas may be less flexible than oil (because it needs an expensive infrastructure to move it to market), but the ratio of reserves to current production is 60 years.
Other alternative energy sources are also emerging.
The attitude of Opec countries to foreign companies also differs markedly now compared to the 1970s. Then, Opec countries were busy kicking out the West's leading oil companies, then known as the "seven sisters".
Today, all but Saudi Arabia are chasing billions of dollars in foreign investment. Some analysts have suggested that the Saudis might be trying to deter such investment by driving prices lower. Certainly, the more expensive projects in both Opec and non-Opec countries look uneconomic in light of present prices. But it will take a prolonged period of low prices to strangle new investment.
There is no consensus about whether oil prices will stay low, or rebound later in the year. On Thursday, Saudi Arabia signalled it welcomed "any concerted efforts by Opec to bring back stability to the oil market". That could pave the way for a reduction in Opec output which could push prices up again.
But barring any breakthrough within Opec, the fundamentals remain gloomy, at least for 1998. "As for oil prices this year there's not much good news in the background," says Mr Mark MoodyStuart, chairman of Shell Transport and Trading, the UK arm of Royal/Dutch Shell.
In recent days many analysts have cut their oil price predictions for the year. The majority fall in a $14 to $18 range. More pessimistic commentators warn that, if Opec does not make room for additional Iraqi oil, the price could slide to single digits.