The rigs to be stacked are Ensco drillships DS-3, DS-4, DS-5 and semi-submursible Ensco 8500, according to a letter from the company to the Texas Workforce Commission.
The layoffs began 11 May.
The company said it could recall some workers if it can secure contracts for the rigs.
All affected employees worked in the US Gulf of Mexico and reported to Ensco's Houston offices.
Ensco
