Gachsaran County (, ) is in Kohgiluyeh and Boyer-Ahmad province, Iran. The capital of the county is the city of Dogonbadan. At the 2006 census, the county's population was 131,628 in 28,551 households. The following census in 2011 counted 119,217 people in 30,399 households, by which time Basht District had been separated from the county to form Basht County. At the 2016 census, the county's population was 124,096 in 34,329 households. This county is known as Iran's oil roof because of the highest oil tower located in this county (Seghalatoun, 3221 feet above sea level) one of the most important and richest areas but more unknown in Iran because of its oil and gas products and it has the second largest (Ahvaz has the first) oil fields of Iran in this county. This county is one of the main heart of energy resources in the world. More than one-quarter of the oil of Iran is exported to all over the world from this county.. This Country is one of the special economic zones of Iran History of capital This city was named Gonbade malghan or Gonbade maljan in the past and now Dogonbadan and Gachsaran. There were two domes, one to the west and one to the east of the city, so the city was called Do gonbadan "between two domes". The city was rebuilt by British staff of the Darcy oil company about 1927. It is reported that this area was also populated with some British residents who owned houses and vast lands not far from the outskirts of the city. Administrative divisions The population history and structural changes of Gachsaran County's administrative divisions over three consecutive censuses are shown in the following table. The latest census shows one district, four rural districts, and one city. Gachsaran Oil & Gas Production The Gachsaran Oil & Gas producing company with a distinct geographical situation stretches over provinces of Kohgiluyeh and Boyer-Ahmad Province, Fars, Busher, Khuzistan and Isfahan. Total production from about 320 wells is 750,000 bd. The main wells have been drilled at reservoirs of Gach Saran, Bibi Hakimeh, Rag-e-Safid, Pazanan, Gulkhari, Binak, Chilingar, Nargesi, Garangan, Kilur Karim, Sulabedar, Siahmakan, Khaviz, Rudak, Zaaeh, Chahr Bisheh and Kuh-e-kaki. Out of these regions Gachsaran Reservoir with 500,000 bd and Siahmakan with 4000bd have the highest and lowest production rates respectively. Gachsaran and Dogonbadan as names of a city are in fact referring