US$250 billion of investment will be needed over 17 years.
Known as Dominique, the 1.5MW facility will be installed in the Gulf of Guinea.
The agreement involves developing a 500MW onshore liquefied natural gas scheme.
Standout opportunities include data centres, manufacturing and infrastructure.
The project is billed as the first facility in Sub-Saharan Africa to combine wind and solar energy in one location.
Six manufacturing hubs are being built across Nigeria.
Ghana's finance minister delivered a mid-year budget review on 31 July.
JER Group has already secured permits for 10,000 hectares of land.
The refinery will have a capacity of 60,000 b/d.
The facility is planned to come onstream by the fourth quarter of 2026.