The consultants will be tasked with identifying which assets would be partially privatised and how, according to a report by US-based Bloomberg.
Banking advisory tenders have not yet been issued.
Various options will be studied, including selling a minority of shares in Aramco itself, or holding companies comprising Aramcos domestic and overseas downstream assets and joint ventures.
Listing individual refinery joint ventures has always been an option, according to a source who worked on the project finance for Sadara and Yanbu.
The $20bn Sadara Chemicals Complex began partial production in late 2015. It is a 50-50 joint venture with US-based Dow Chemicals.
The $10bn Yanbu export refinery was completed in 2014. Aramco owns 62.5 per cent in a joint venture with Chinas Sinopec.
The $9.6bn Jubail refinery has also been identified for a possible IPO. Frances Total has a 37.5 per cent stake in the project company Saudi Aramco Total Refinery & Petrochemical Company (Satorp). Several petrochemicals firms such as Rabigh Refining and Petrochemical Company and Yanbu National Petrochemical Company are already listed on the Tadawul.
The potential public listing of Aramco shares was revealed by Deputy Crown Prince Mohammed bin Salman in an interview with The Economist published on 7 January.
Capital Economics estimates Aramco could be worth anything from $1 trillion to upwards of $10 trillion. However, Riyadh is unlikely to relinquish a controlling stake in its main source of revenue.
The primary listing is expected to take place on the Saudi exchange, the Tadawul.