Sources say it's looking to slash up to 40% off the cost of producing oil and gas.
They say the major cash-saving drive will allow it to focus more on renewable energy and power markets.
The restructuring, known internally as Project Reshape, will reportedly affect its main divisions.
And any savings will come on top of a $4 billion target set in the wake of the COVID-19 crisis.
Reducing costs is vital for Shell's plans to move into the power sector and renewables, where margins are relatively low.
Competition is likely to intensify, with rival firms including BP and Total all battling for market share, as global economies go green.
A senior Shell source who declined to be named, told Reuters,"we had a great model but is it right for the future? There will be differences, this is not just about structure but culture and about the type of company we want to be."
Sources added that Shell wants to focus its oil and gas production on just a few key hubs, including the Gulf of Mexico, Nigeria and the North Sea.
The company's integrated gas division is also thought to be looking at deep cuts.
Shell's network of 45,000 service stations - the world's biggest - may also see cuts.
The review, which company sources say is the largest in the firm's modern history, is expected to be completed by the end of the year.
