THE GUNPLAY OFF the Libyan coast brings, reasonably enough, anxious questions about oil supplies. But this time you don't have to worry. The Libyans have destroyed their own oil weapon. It's an instructive case of a strategy that worked too well.

Ten years ago, after Col. Muammar Qaddafi and his military friends had thrown out King Idris and established their revolution, they began asking whether oil wasn't priced too cheap. It was going for $1.90 a barrel. Everybody told them that they were crazy--the oil companies, the oil-importing countries, even the powerful oil-producing countries of the Persian Gulf. But the state of their mental health turned out to be irrelevant because, on the matter of oil prices, they were quite right. They raised their prices a little. To everyone's astonishment, the new prices stuck, and the bigger producers nervously followed them.

Then, as you doubtless recall, the movement upward suddenly accelerated--assisted by various wars and revolutions. Nothing goes to a government's head faster than the discovery that it is right. The Libyans, in a state of aggravated hubris, kept shouting that the sky was the limit and became the leaders of the high fliers within OPEC. When Saudi Arabia raised its basic price to $32 a barrel at the beginning of this year, the Libyans were selling their oil at $41.

But meanwhile consumers were reacting to the succession of price increases, and oil sales were dropping rapidly. Saudi Arabia, having kept its oil at the bottom of the world price range, was having little difficulty selling as much as it chose. But the countries at the top of the range--Libya and the other two major African producers, Nigeria and Algeria--were running into trouble. Their customers were walking away.

In the industrial world, the determination to cut oil imports has now acquired great momentum, and the demand for oil is likely to keep dropping. There's more oil being produced than--at today's prices-- the buyers want or need. National pride and revolutionary fervor make it awkward for Libya to reduce its prices much, and impossible to compete directly with Saudi Arabia. To the customers, one barrel of oil is very much like another and, as long as there is more for sale than the customers want, the sellers with the highest prices have the least leverage. Ten years ago, or even two years ago, the Libyans had great influence in the world oil market. Currently, having far overplayed their hand, they have none.