US independent Apache said a relief rig is en route to the location of an offshore Louisiana well where natural gas has been said to be flowing underground for more than a week.
According to US media reports, non-essential staff were evacuated from the shallow-water well that was being drilled by the jack-up Ensco 87 at Main Pass 295 in the Gulf of Mexico.
Houston-based Apache spokesman Bill Mintz confirmed in an emailed response to Upstream that the well began flowing natural gas on 4 February.
“The well was shut in, and the blowout preventers are functioning properly,” he said.
However, testing had detected an underground migration of gas from the bottom of the well (about 8261 feet) to a shallower sand formation at about 1100 feet below surface.
Mintz said Apache was now working with Boots and Coots well control experts to kill the well.
He added that at the direction of the Bureau of Safety and Environmental Enforcement, the company was mobilising another jack-up rig, Rowan Cecil Provine, to the well location in case the drilling of a relief well was necessary.
No one was injured in the incident, Apache said.
It did not offer an explanation of the perceived cause of the underground gas movement.