Less than a year since president Hugo Chávez seized control of the vast oil fields in Venezuela's Orinoco belt, executives from international energy companies are back, armed with smiles, pens and cordial handshakes.

US oil groups ExxonMobil and ConocoPhillips spurned the compensation offered by Caracas, preferring to fight it out in the courts - Exxon is awaiting a ruling in London this week. But France's Total, Norway's Statoil-Hydro and Italy's Eni have signed potentially significant new deals.

Eni's deal to develop an area of the Orinoco belt could be worth more than $4bn (€2.6bn, £2bn) and there may be more tie-ups in the offing.

"Venezuela has oil, and plenty of it. As long as there is a window of opportunity for a company to operate and make some profits, greed will always win through," says Roger Tissot at PFC Energy, the consultancy.

Despite the president's hardball tactics, Venezuela's enormous reserves - by some measures the largest in the world, with more than 300bn barrels recoverable - seem too good an opportunity to miss. In a context of record high oil prices that show no signs of falling, companies may be willing to take the gamble.

PDVSA, Venezuela's state-owned oil company, certainly needs help and international oil groups may be its best option, particularly in the short term. In turn, Mr Chávez needs PDVSA: he depends on Venezuela's abundant oil wealth to bankroll his socialist revolution as he struggles with an unstable economy riddled with distortions that cause problems such as inflation and shortages.

PDVSA has set itself the ambitious goal of almost doubling production by 2012, from over 3m barrels a day - according to official data that even government figures privately question - to almost 6m. However, most analysts say this target is unrealistic.

"Undoubtedly, PDVSA could never do this alone," says Mr Tissot.

Developing the particularly heavy oil reserves in the Orinoco region involves a complex refining process known as "upgrading", in which some international oil companies have developed considerable expertise and experience, while most national oil companies have not.

"There are areas where PDVSA needs support, and that is what we are here to provide," says Thore Kristiansen, who runs Statoil-Hydro's operations in Venezuela.

The deals with Total, StatoilHydro and Eni suggest a growing awareness in the Venezuelan government that it needs as many players as possible to maximise the potential of the Orinoco belt. Help from outside is all the more necessary if Mr Chávez is to achieve his aim of reducing dependence on the US oil market.

The timing of the deals is indicative of PDVSA's attempts to prove its willingness to work with private companies, says Patrick Esteruelas at the consultancy Eurasia Group. That image may help it in the legal dispute with Exxon, which is attempting to freeze more than $12bn of PDVSA's global assets through the British High Court. Exxon argues that the state company does not intend to compensate it fairly.

Nevertheless, none of the European companies have yet made big new investments in the Orinoco belt, even if they have secured the possibility of doing so in the future. So far both private and state-owned oil companies operating there have committed themselves only to certifying reserves - which requires minimal investment - rather than to exploring or developing them.

"Are the companies committing to work with the Chávez administration despite all the risks attached? Or are they betting on the long haul, hoping to secure a foothold in Venezuela before Chávez is eventually forced to loosen terms for private investment, or should he be replaced by a more market-friendly administration?" asks Mr Esteruelas.