Abu Dhabi Marine Operating Company operates the Concession Area on behalf of its shareholders. The Concession Area was granted by the Abu Dhabi Government in March 1953 with an original total area of 30,370 square kilometers.   More than 300 wells have been completed in the oil and gas bearing Umm Shaif reservoirs. These wells include oil and gas production wells from the oil and gas reservoirs, as well as water and gas injection wells.   In Zakum there are more than 340 wells which have been completed as producer, injector or observation / suspended status in the oil and gas bearing Zakum reservoirs. The production / injection wells in the field are accommodated on 111 towers. This is in addition to one tower [ ZK-20A ] which serves as a manifold. The towers installations were initiated in 1964.   US field was discovered in January 1958 and the first crude oil shipment was exported on 4th of July 1962. major fields operated are Umm Shaif and Zakum. Production was started mainly from Arab D reservoir with little from Arab C and Thamama reservoirs. At present, crude oil production is mainly from Arab C & D reservoirs.