The navy rescued the workers using a frigate and boats, Ramirez said. The gas platform disappeared into the Caribbean Sea at 2:20 a.m.
President Hugo Chavez announced the sinking on Twitter early Thursday, saying: "To my sorrow, I inform you that the Aban Pearl gas platform sank moments ago. The good news is that 95 workers are safe."
Officials are investigating what could have caused the platform to sink, Ramirez said. He said there was a problem with the flotation systems of the semi-submergible platform that led to a massive water leak in one area.
He said alarms went off three hours before the sinking, giving the crew time to evacuate. Three workers including the captain stayed behind until it was clear that the platform was at risk of collapsing, and then abandoned the rig, Ramirez said.
He said a tube connecting the rig to the gas field was disconnected and safety valves shut. "There's no problem of any sort of any leak from the field into the environment," Ramirez said.
Last week, Ramirez stood atop the rig on live television as its gas flare was lit to inaugurate the project. Chavez praised the project at the time as an important step in Venezuela's efforts to tap its huge natural-gas deposits.
The exploration platform at the Dragon 6 gas field was operated by the state energy company Petroleos de Venezuela SA off the Paria Peninsula of eastern Venezuela, near Trinidad and Tobago.
Venezuela, a major oil exporter and OPEC member, is exploring offshore natural gas fields that are among the biggest known deposits in the world.