Azeri–Chirag–Gunashli (ACG, Azerbaijani: Azəri-Çıraq-Günəşli) or Azeri–Chirag–Deepwater Gunashli is a complex of oil fields in the Caspian Sea, about 120 kilometres (75 mi) off the coast of Azerbaijan.

The ACG fields have estimated recoverable reserves of about 5 to 6 billion barrels (790 to 950 million cubic metres) of petroleum.

However by the first quarter of 2024 production had fallen to 339,000 barrels per day (53,900 m3/d), or approximately one-third of peak value, as the development continued terminal decline.

In January 1991, the Azerbaijani government announced separate international tenders of exploration rights for Azeri, Chirag, and Gunashli fields.

In June 1991, a consortium of Amoco, Unocal, British Petroleum, Statoil, McDermott, and Ramco was formed for a development of Azeri field.

After Heydar Aliyev became President of Azerbaijan in 1993, talks with foreign companies were stopped and Lukoil was invited to the consortium.

[8] The production sharing agreement (PSA) was signed by the parties on 20 September 1994 for development of the fields for 30 years.

It injected first gas in May 2006[12] The West Azeri drilling modules arrived in Baku in August 2004 and the platform launched in May 2005.

[12] East Azeri drilling modules and quarters arrived in Baku in June 2005 and the platform was launched in March 2006.

The final investment decision on the Azeri Central East (ACE) platform, which is planned to be built on the Azeri–Chirag–Gunashli (ACG) block, has been adopted at the signing ceremony.

[2] The founding consortium formed to develop the Azeri–Chirag–Gunashli project initially included BP, Amoco, Unocal, Statoil, McDermott, Turkish Petroleum, and Ramco Energy.

[25] In 2023, Norway's Equinor divested all of its assets in Azerbaijan, including its stakes in the Azeri–Chirag–Gunashli development and the Baku-Tbilisi-Ceyhan oil pipeline.

[27] Of Equinor's original 7.27% interest in ACG, 6.655% reverted to SOCAR, the State Oil Company of the Republic of Azerbaijan, and 0.615% to ONGCVidesh.

As of the first quarter of 2024, the remaining participating shareholders of the Azeri–Chirag–Gunashli development were BP with a 30.37% stake, SOCAR (31.66%), MOL (9.57%), INPEX (9.31%), ExxonMobil (6.79%), TPAO (5.73%), Itochu (3.65%) and ONGCVidesh (2.93%).

West Azeri (WA) had 18 wells in operation (14 of which are oil producers and 4 - water injectors with production of 275,200 barrels per day (43,750 m3/d).

East Azeri (EA) had 13 wells in operation (9 of which are oil producers and 4 - water injectors) with an overall production 139,400 barrels per day (22,160 m3/d) for the first three quarters of 2009.

[31] Oil depletion rates of each of the Azeri–Chirag–Gunashli reservoirs are expected to differ over time, with aggregate output from the complex declining substantially after 2018.