The two countries agreed on Tuesday to create joint companies to improve Ecuadorean refineries and for the transportation and storage of natural gas. The joint ventures will also facilitate oil exploration and production.
Chavez was visiting Quito, the Ecuadorean capital, weeks after the country terminated a contract with Occidental Petroleum, a US-based company with which Ecuador is in dispute.
Chavez made a commitment to refine up to 100,000 barrels of Ecuadorean oil a day.
He congratulated his counterpart, Alfredo Palacio, for recovering Ecuador's natural resources. He was referring to Ecuador's decision to terminate Occidental's contract over accusations that it illegally sold part of an oil block without government authorisation.
Petroecuador, the state oil company, took over operations at the oilfields, but some industry observers doubt that it can keep up production for long.
Ecuador says it wants to agree a joint venture with another Latin American oil company to operate the oilfields. Venezuela's PDVSA is one of the candidates.
Chavez has promised to invest
$1.5bn in Bolivia's gas industry
Occidental says it did nothing wrong and has filed an arbitration claim in Washington seeking $1 billion in damages.
Ecuador has little refining capacity and this year expects to spend $1.7 billion on petroleum-based products imports, or 20% of the national budget.
It stands to save $300 million a year on fuel imports through the deal with Venezuela to refine its crude at a lower cost. The deal will start in about 45 days, officials said.
In a similar trip to Bolivia last week, Chavez promised to invest $1.5 billion in the impoverished country's natural gas industry. Evo Morales, the Bolivian president, nationalised the energy sector this month.