Chevron is expected to sign an agreement on Monday to return a gas field to Venezuela and participate in an additional heavy crude area in the country’s main oil field, while Shell will sign an agreement to acquire the Loran gas field for operation, three sources close to the preparations said. The agreements are part of expansions and changes since the US launched a $100 billion reconstruction plan for Venezuela’s energy sector after ousting Venezuelan President Nicolas Maduro, and sweeping reforms to the country’s key oil law were approved in January to encourage foreign investment.

The agreements, the exact terms of which are still unknown, are expected to be signed by the companies in the presence of the oil ministry and state-owned company PDVSA in the presence of Acting President Delcy Rodriguez, the sources said on condition of anonymity.

Chevron and Venezuela’s oil ministry did not immediately respond to requests for comment. Shell declined to comment, but the energy major previously told Reuters that Loran was an attractive investment opportunity as it expands into its Manatee field in Trinidad and Tobago.

Shell has been in advanced talks with the Venezuelan government in recent weeks to develop oil and gas fields in the South American country, including Loran, sources told Reuters earlier this month. In March, it signed a preliminary agreement with the Rodriguez administration to advance the Dragon gas project and the Carito and Pirital onshore crude and gas fields.

Chevron is in parallel talks to abandon Loran, which it explored and confirmed years ago as having more than 7 trillion cubic feet of reserves, but did not develop. The US major is now focused on expanding its flagship oil project Petropier in Venezuela to the neighboring Ayacucho 8 field in the wider Orinoco belt.