The federal government has revoked the licences of 11 marginal field operators.
The affected companies include Movido–Ekeh, Goland – Otiti, Independent Energy – Ofa, Associated-Tom Shot Bank, Bayelsa – Ayala, Sogenal – Akeni and Delsigma–Ke.
Others are Bicta–Ogedeh, Guarantee–Ororo, Eurafic-Dawes Island and Sahara–Tsekelewu.
The affected companies were given letters on Monday.
The operators were awarded the fields in 2003.