UPDATE 1-Shell expects to shut all Gulf output in 2 days

(Adds details about Shell production, evacuation plans, paragraphs 2-5)

HOUSTON, Aug 28 (Reuters) - Shell Oil Co (RDSa.L) said on Thursday evening it expects to shut all of its Gulf of Mexico production over the next two days as it evacuates workers from offshore platforms due to the threat of Tropical Storm Gustav.

Shell is the largest producer in the Gulf of Mexico with an average of 370,000 barrel per day of oil equivalent, according to the company.

Shell began evacuating offshore workers on Wednesday and starting turning off some production wells on Thursday.

A total of 350 workers were evacuated on Thursday. Shell flew 400 workers onshore Wednesday. The company has a staff of 1,300 workers in the Gulf. All workers are expected to be onshore by Saturday.

Shell does not individually report the amount of production it shuts due to storms in the Gulf. (Reporting by Erwin Seba; Editing by David Gregorio)