A system is provided for the production of heavy crude oil from an undersea reservoir, and for the treatment of the crude oil to facilitate its transport. A floating body (12) which produces the heavy crude oil, carries a hydrocarbon cracking station (32) that cracks the heavy crude into light liquid and gaseous hydrocarbons, and that uses heat resulting from the cracking to produce pressured steam. The pressured steam is used to drive a steam-powered engine (72) (with pistons or a turbine) that drives an electrical generator (74) whose electricity powers the system.