No injuries or fires were reported and, as a precaution, 47 workers at the site were evacuated.
Although the Bureau of Safety and Environmental Enforcement (BSEE) reported seeing a sheen of about a half-mile by 50ft, it said it was dissipating swiftly.
Walter Oil & Gas, who Hercules operates the rig for, reported a loss of control of Well A-3 on an unmanned platform at South Timbalier Block 220, while doing completion work on the sidetrack well.
The purpose of the sidetrack well in this instance was not clear.
BSEE is closely monitoring Walter Oil & Gas’ mobilisation of its response efforts to stop the flow of gas and secure the well.
The agency is also working in association with the coastguard and other federal agencies on response efforts.
Earlier in July, a gas well flowed for few days off the Louisiana coast before it was closed.
In 2010, an oil rig exploded off the state’s coast, leading to a blowout that spilled millions of gallons of oil into the Gulf of Mexico, leading to one of the worst offshore disasters in the US history.
Image: Gas flowing at the blowout well. Photo: courtesy of BSEE.