Chevron shut in drilling on Tuesday afternoon at its Moccasin prospect in the Gulf of Mexico after about 400 barrels of drilling fluid escaped under water due to an apparent equipment failure, the company confirmed to Upstream.
Transocean's Discoverer India drillship was at work on an appraisal well in Keathley Canyon Block 736, in 6400 feet of water about 216 miles off the Louisiana coast.
The incident took place just before 4 pm local time, according to an initial report to authorities obtained by Upstream.
That report said the drilling mud was released from the blowout preventer due to an equipment failure, after which the release was secured.
"Chevron is inspecting subsea equipment to address the situation," the company said in a statement.