CARACAS, Venezuela – President Hugo Chávez is spending more than $7 billion of oil revenue this year to help Venezuela's poor, and they love him for it.

But in the downtown business district, over and over again you hear allusions to one of Aesop's fables.

"You don't want to kill the goose that lays the golden eggs," said Elio Ohep, editor of Petroleumworld.com. "If you scare away investment, what are you going to do?"

Venezuela's president is seeing how far he can push international oil companies such as Exxon Mobil Corp.

In the last several months, Venezuela's government has raised royalties, taxes and government equity in dozens of oil projects. In April, a Venezuelan congressional report urged Mr. Chávez to take similar steps with four heavy oil projects run by multinational companies in the Orinoco River belt, possibly the world's largest oil province.

The measures would put the national oil company in charge, give Venezuelan courts exclusive jurisdiction over disputes and shift billions of dollars from the companies to Mr. Chávez's regime.

Gersan Zurita, an oil analyst with credit evaluators Fitch Ratings in New York, said the moves would essentially turn the private oil companies into silent partners in an oil business that would be run by Venezuela.

The struggle will affect future company earnings, Venezuela's economy and future world oil supplies.

With oil prices soaring and new oil fields hard to come by, Mr. Chávez has the upper hand.

"Twenty-six companies decided to go to the new system," said Bernardo Alvarez, Venezuela's ambassador to the United States and a former deputy energy minister. "It was 100 percent legal."

When French company Total SA and the Italian firm Eni SpA balked, Mr. Chávez sent the national guard to seize their fields.

Exxon Mobil sold its interest in one oil field, shut in another, reserved its right to seek arbitration over government royalty hikes and was removed from a petrochemical venture by the Venezuelan government.

The company says it's in Venezuela for the long haul, but it could still come to blows with the government over an Exxon-managed $1.6 billion heavy oil project in the Orinoco belt.

That possibility led Fitch Ratings and Moody's to downgrade the project's debt, along with the debt of three other Orinoco projects, in May.

Exxon Mobil chairman Rex Tillerson isn't backing off. In March, he said the company would refrain from any major new investments in Venezuela. Asked in May whether the Orinoco was too big to walk away from, Mr. Tillerson told The Dallas Morning News: "Well, nothing's too big to walk away from for us."

Exxon Mobil takes a hard line with any government that tries to change contract terms, whether it's Mr. Chávez or the U.S. Congress, which wants to roll back royalty relief for offshore drilling that was enacted when prices were low.

But when companies weigh political risks against the geologic risks inherent in looking for oil, many of them decide to ride out a rough political climate.

"There's a low risk in Venezuela for discovering oil, and these companies know that," said Alejandra Leon, an oil analyst in Mexico City with Cambridge Energy Research Associates. "They are able to pay higher royalties in exchange for more access because it's getting harder and harder to gain access to oil reserves."

Venezuela has the oil. Its proven reserves of 79.7 billion barrels rank seventh in the world, and Venezuela could take the top spot from Saudi Arabia if it can demonstrate that even 10 percent of the 3 trillion barrels of thick, tarry oil in the Orinoco belt is economically recoverable.

In the 1990s, Venezuela lured multinational companies to older fields and the difficult Orinoco belt with generous terms. As part of a strategy called the apetura, or opening, Orinoco projects faced royalties of just 1 percent.

Petroléos de Venezuela, or PdVSA, Venezuela's national oil company, took a minority stake in the projects (though its preferred shares gave it the key voice in overall strategy). Income tax on the projects was set at 34 percent, and the contracts called for disputes to go to arbitration in New York.

Exxon Mobil, ConocoPhillips Co., Chevron Corp., Total SA, BP PLC and Norway's Statoil ASA have more than $16 billion invested in the four projects, which together produce more than 600,000 barrels a day of crude oil upgraded from the thick, gunky deposits.

In May, the National Assembly, which is made up entirely of Chávez loyalists, enacted a new 33.33 percent extraction tax. The government raised the income tax rate to 50 percent. Royalties were raised to 16.7 percent.

The recent report by an assembly committee recommended nearly doubling the new royalty rate while giving PdVSA a 60 percent share in each project.

Fitch Ratings' Mr. Zurita then wrote a special report on the situation called "Venezuela's Heavy Oil Projects: The Beginning of the End?"

Venezuela, he warned, is scaring off foreign investors.

"Some of these companies have become less and less tolerant of fiscal instability and changes in the rules in midstream," Mr. Zurita said. "So it's not surprising to us that we see huge amounts of investment, sums like $700 million a month, going to the [Persian] Gulf, where countries like Qatar are moving very much in the opposite direction of Chávez."

E-mail jlanders@dallasnews.com