Australia's petrol supply sector looks set for another major shake-up with plans emerging for a potential $2 billion-plus initial public offering of Viva Energy, which acquired Shell's oil refining and marketing business in 2014 and has since embarked on a journey of expansion and upgrades.

Viva's majority owner, Swiss oil trader Vitol, is understood to have kicked off early preparations for a float of the business, which comprises a refinery in Geelong and a network of about 20 fuel import terminals and could be worth about $5 billion in total.