The oil projects were in Chaharmahal-Bakhtiari, Khuzestan and Bushehr provinces in west, southwest and south of the country respectively, IRNA reported.
About 30,000 billion tomans have been allocated to the projects.
Rouhani officially ordered commissioning of the centralized storage tanks of South Pars worth €29.2 million and Rls.2.2 billion, Mehr News Agency wrote.
The project for constructing storage facilities and gas condensate measuring stations is aimed at storing gas condensate from a number of South Pars refineries with a nominal capacity of 640,000 cubic meters, an equivalent of 4 million barrels.
President Rouhani also officially inaugurated the first skid-mounted oil refining unit on Thursday.
This processing unit (Skid-Mounted) was constructed in the form of a lease and purchase contract for oil refining services ($1,285 per barrel) with the private sector (foreign).
The value of the contract is $47 million, and the construction site is on the south side of the South Azadegan oil field in the West Karoun oil fields cluster. It is fed by 35 wells and its processing capacity is 50,000 barrels per day, which can be enhanced to 80,000 barrels.
The third project inaugurated by President Rouhani on Thursday was the Lordegan Petrochemical Plant in Chaharmahal-Bakhtiari province.
The commissioning of the complex was fully carried out by Iranian experts and it will generate roughly $240 million annually once becoming fully operational.
The plant has been built with the aim of producing 1.075 million tons of urea and 677,000 tons of ammonia per year, of which about 600,000 tons is used to produce urea in the complex.
The facility is fed by natural gas from the national gas distribution network. It consumes 320 million cubic meters of natural gas as fuel and 429 million cubic meters of natural gas as feedstock annually.
Most of the products of this complex is for export and its first chemical shipment will be exported next month.