The Trans-Caspian Oil Transport System is a proposed project to transport oil through the Caspian Sea from Kazakhstani Caspian oilfields to Baku in Azerbaijan for the further transportation to the Mediterranean or Black Sea coast. The main options under consideration are an offshore oil pipeline from Kazakhstan to Azerbaijan, and construction of oil terminals and oil tankers fleet. A strong push for the project has been from the partners of the Kashagan oilfield project and in particular Total who has a share in both the field and the BTC pipeline. They have estimated that such a project would cost roughly US$4 billion. The project also faces opposition from Iran and Russia, both alternative avenues for Kazakhstan's oil and gas who would likely object to competing pipelines being built.
In 2005, the Government of Kazakhstan adopted plans for creation of a trans-Caspian westbound route for oil export. On 19 June 2006, President of Kazakhstan Nursultan Nazarbayev and President of Azerbaijan Ilham Aliyev signed a framework agreement on the trans-Caspian oil transport system. On 24 January 2007, partners in TengizChevroil (developer of Tengiz field) and KCO (Kashagan field developer)signed a memorandum of understanding to create a trans-Caspian oil transport system. On 2 October 2009, the national oil company of Kazakhstan Kazmunaygas and the State Oil Company of Azerbaijan Republic signed a memorandum of understanding to expand the Caspian Oil Transport System to include Azeri infrastructure and onshore pipelines from Baku to Kulevi oil terminal in Georgia.