Straight from the source: Hugo Chavez tweets semisub sinking.
Aban Pearl reported trouble last year
Crew evacuated to Neptune Discoverer
Aban Offshore's Aban Pearl semi-submersible drilling rig that sank into the Caribbean early this morning almost sunk off Trinidad & Tobago last year.
Trinidad’s Coast Guard responded to a call to evacuate the rig in August when it was off the coast of that country and en route to Venezuela.
Previous reports state that the rig began to list after its flotation devices took on water in heavy seas about two nautical miles south-west of Point Baline, Gasper Grande Island
The Coast Guard responded to a call to evacuate the 90-person crew but was later told the rig had been stabilised, according to a report in Trinidad & Tobago-based Newsday.
Venezuelan President Hugo Chavez announced the sinking of the Aban Pearl today in a message sent out on social media platform Twitter.
The semisub was operating for Venezuela's state-run producer PDVSA at the Mariscal Sucre complex development under a five-year contract which came into effect last year.
Venezuela's Oil Minister Rafael Ramirez later told Reuters that the accident was caused by water entering a subsea pontoon, adding that that there are plans to try to retrieve the unit.
In his tweet, Chavez said all 95 crew on the rig were evacuated safely.
Chavez' first tweet said: "To my sorrow, I want to inform that the natural gas platform Aban Pearl sunk a few moments ago. The good news is that the 95 workers are safe."
Aban Offshore later issued a statement saying the semisub was evacuated "following an incident ... which impacted its stability".
It did not give further details.
A contractor told UpstreamOnline that the crew was taken to the drillship Neptune Discoverer, which was drilling a well nearby.
According to PDVSA's website, the Aban Pearl was operating in water depths of 160 metres at the time of the accident.
Meanwhile, Ramirez, who is also the head of PDVSA, said the sinking of the rig poses no risk to the environment.
It later emerged the semisub was working at the Dragon field. It is believed it was drilling the Dragon-6 well at the time of the incident.
Ramirez told Venezuelan media that the well the rig had been drilling had been stabilised and there was no risk of leaks.
Local media quoted him saying rig listed before sinking at about 2 am, local time. The region is known for strong waves, a state television reporter said.
"The safety valves activated along with an additional security mechanism, which allows us to affirm that we have stabilised the well and there is no risk of any kind of gas leak," Ramirez said.
It was too early to determine the cause of the accident, he added.
PDVSA later issued a statement saying the well had been sealed before the rig sank.
The Dragon dry gas field is within the larger Mariscal Sucre complex.
The field is scheduled to come on stream by 2012, but the wider Mariscal Sucre project also includes the Patao, Mejillones and Rio Caribe fields, featuring dry gas, wet gas and gas with condensates respectively.
The Dragon field will produce between 600 million and 700 million cubic feet of gas per day.
Dragon is expected to feature subsea completions from eight wells, a gathering platform and a 115-kilometre, 36-inch pipeline to a gas processing base on the Paria peninsula.
PDVSA believes Mariscal Sucre holds an estimated 14.7 trillion cubic feet of gas. Once completed, the development will pump 1.2 billion cubic feet of gas per day and 20,000 barrels per day of condensate.
Last year, PDVSA said total investment across the Mariscal Sucre the project would hit $8.4 billion in the six years to 2015.
It is understood the Aban Pearl was previously named named Bulford Dolphin and owned by Norway's Fred Olsen. Fred Olsen sold the unit in 2007, when it was 20 years old.
The Aker H-3 design rig was built in 1977 by Far East Levingston at the Levingston Singapore shipyard.