LIKE the supertankers which ferry their products all over the world, the oil giants are not going to change course because of a temporary problem of weak oil prices.

Smaller companies are different - there has been a sharp downturn in their exploration spending to preserve cash flow following the downturn in crude.

But BP pointed out that its exploration and appraisal programmes were aimed at future production in the next millennium, and it would take a long period of low oil prices to alter its horizons. The group sets its investment assumptions based on a low price of some $14 a barrel and exploration costs have been on a downward trend for some years thanks to advances in technology, particularly in the sub-sea area. This trend is expected to continue.

However, no-one knows what will happen to oil prices and a long period of low prices would eventually impinge even on the oil giants.

The current depressed level has flowed from the Asian economic downturn, an unusually mild winter in the northern hemisphere, and production increases. There is a glut of oil, but optimists point to the moves afoot by Opec to restrict output, and to the unwinding of the El Nino effect. The winter following an El Nino event is apparently often severe.

However, it is notoriously difficult to get Opec to agree on cuts without some members cheating on their quotas, and Saudi Arabia refuses to be the ''swing'' producer any longer. A cold winter might provide some upward blips but might only enable the price to remain around $15 a barrel rather than falling lower.

Whatever BP's optimism about its ''self-help'' programme, flat oil prices would mean flat profits. For investors, the oil sector only looks a hold, though any significant weakness in the shares would be a buying opportunity for the long-term.