Santos will sell its entire working interest of the Evans Shoal natural gas field (NT/P48) in the Bonaparte basin, offshore Australia, for $350m.
The field will be sold to a major international exploration and production company operating in Australia.
On completion of the transaction, Santos will receive $250m in cash and a contingent future cash payment of up to $100m.
Santos will complete the deal by the end of 2011, subject to regulatory approval.
Santos, as the operator, holds a 40% interest in the gas field, with other shareholders including Petronas and Shell (25% each) and Osaka Gas (10%).