Wellington, New Zealand — New Zealand is in the grip of an oil rush, and a billion-dollar exploration boom is sending shock waves through stock exchanges here. Three offshore drilling rigs are already operating, and there is talk of a fourth next year. Ten wells are to be drilled in and around these South Pacific islands in the next year as government and private companies seek the ''big find'' that will transform the nation's agriculture-based economy.
Investors, big and small, have rushed to pour more than $100 million (US) into new oil companies in recent weeks. Share prices have seesawed with every rumor, prompting Prime Minister Robert Muldoon, who is also finance minister, to warn that buying oil shares is like putting money on the horses.
At one stage, the Auckland Stock Exchange called in the police to maintain order as investors and the curious mobbed the trading floor.
In the last month, two major exploration wells have been declared dry, provoking sharp drops on the volatile oil-share market. Shares have also gone down under heavy selling pressure on favorable reports, such as confirmation of the presence of hydrocarbons. This proves, commentators say, that a large number of tyros, out for quick profits, have entered the market.
''They get caught up in the enthusiasm and excitement of mining and oil shares,'' says John Aburn, New Zealand Stock Exchange president.
''Some investors will make it rich; others will get their fingers burnt,'' says Bruce Buxton, chairman of the exchange.
The exploration figures here may not be big by world standards. But they are huge in New Zealand terms, and their potential importance to the country is enormous.
Until very recently, New Zealand was totally dependent on imports for transport fuel. The oil price rises of 1973 savaged the economy. Last year, New Zealand paid out nearly $2 billion for imported oil - just about equal to the country's cash deficit on its trade with the rest of the world. (Prices for agricultural exports have not risen nearly as fast as oil prices.) A major oil find would help restore the trade balance.
New Zealand hopes to provide half its own transport fuel by 1988 through use of compressed natural gas, liquefied petroleum gas, and production of synthetic gasoline made from natural gas discovered in the 1960s.
Hopes for a big oil find are high, and prospects are good. Oil was, in fact, struck in Taranaki Province on the west coast of North Island back in 1906. But exploration over the next 30 years failed to find commercial quantities. Nearly 100 onshore and 30 offshore wells have been drilled since 1939.
Taranaki produced the onshore Kapuni gas field and the offshore Maui, one of the largest in the world. In 1980, the McKee oil field was discovered in the same province. It and two nearby fields will be producing 6 percent of New Zealand's oil needs by 1985. Taranaki remains a focal point of the oil search. Other key areas are off South Island.
The Texas-based Hunt International Petroleum, through its operator Placid Oil , is currently drilling 225 kilometers offshore in the Great South Basin, an area described as similar to Britain's North Sea. Weather and sea conditions are appalling. The first wildcat was declared dry last month, but Hunt, which found evidence of oil in three wells in the region in the 1970s, is confident there is an economic field there.
The New Zealand government, which has a major stake in the oil search through the state-owned Petroleum Corporation of New Zealand, is also confident.
''Such is the size of some of the geological structures both in Taranaki and in the Great South Basin,'' Prime Minister Muldoon says, ''that even one find could produce a major increase in New Zealand's proven energy resources.''