Formation of the Azeri–Chirag–Gunashli development started in the beginning of 1990s. In January 1991, the Azerbaijani government announced separate international tenders of exploration rights for Azeri, Chirag, and Gunashli fields. In June 1991, an consortium of Amoco, Unocal, British Petroleum, Statoil, McDermott, and Ramco was formed for a development of Azeri field. Azerbaijan was represented in the consortium by SOCAR. Negotiations were expanded to include all three fields. After Heydar Aliyev became President of Azerbaijan in 1993, talks with foreign companies were stopped and Lukoil was invited to the consortium. Negotiations resumed in 1994. The production sharing agreement was signed by the parties on 20 September 1994 for development of the fields for 30 years. The day of the signing of PSA agreement is celebrated as "The Day of Oilworkers" in Azerbaijan.