SOCAR already has a 25% share in ACG, 25% in BTC via Azerbaijan BTC Ltd. and 50% in Karabagh.
Equinor has had a presence in the country since 1992.
ACG, operated by bp, is the largest oil field in the Azerbaijani sector of the Caspian Sea. BTC transports the produced crude to the Turkish Mediterranean coast.
Closing of the transaction remains subject to regulatory and contractual approvals.
Equinor and SOCAR have also signed a memorandum of understanding to share experience and best practice on low-carbon solutions, cutting emissions and carbon management.