The Marjoram-1 well is located 180km off the Malaysia coast in Block SK318, in 800m of water.
Earlier in 2014, the company discovered gas at Rosmari-1 well, which is also located in the same block.
Shell Upstream International director Andrew Brown said: "Our strategy to expand our heartland areas through technologically advanced exploration is delivering tangible success in deep-water in Malaysia.
"We have a long history in the region, and the addition of new natural gas resources this year ensures we are able to continue to provide cost-effective, reliable, cleaner energy options for the future."
Shell holds 85% in the Block SK318, with the remaining 15% held by Petronas Carigali.
