Natural Gas has become the chief focus of Omans economic diversification strategy. Intense exploration has raised proven natural gas reserves from only 12.3 trillion cubic feet (Tcf) in 1992 to its current level of 29 Tcf, according to the Oil and Gas Journal. The government is also continuing its aggressive exploration campaign. Most of Omans reserves are in PDO-owned areas, and the company is Omans biggest natural gas producer. Most natural gas in Oman is associated with oil, but even that which is non-associated is often located close to the countrys oil fields. More than 10 Tcf of Omans non-associated natural gas is located in deep geological structures, many of which are beneath active oil fields. In 2003, Oman produced 583 billion cubic feet (Bcf) of natural gas. In addition to the PDO, a number of foreign firms are involved in Omans natural gas sector. In September 2003, Atlantis, a subsidiary of the Chinese firm Sinochem, began to drill a gas find containing up to 300 Bcf. Gulfstream (now Anadarko) was the first private company to be awarded an onshore gas concession. In August 2001, it received a fixed price gas sales agreement with the government and a 100% concession to develop three gas fields it discovered in Haffar Block 30. Anadarko has already drilled an exploratory Well, and hopes to reach an eventual output level of over 80 million cubic feet per day. The field has proven reserves of 300 Bcf.