With proven oil reserves of 4 billion barrels and 83 Tcf of proven natural gas reserves as of 2009, Malaysia is situated by the Strait of Malacca, a significant energy corridor linking the Indian and Pacific Oceans. Nearly all of the Australasian country's oil is harnessed from offshore fields located on a continental shelf comprised of the Malay basin to the west and the Sarawak and Sabah basins in the east. Malaysia's largest foreign oil company by production volume is ExxonMobil, through its local subsidiary Esso Production Malaysia Inc., and the country's oil and natural gas industry is headed by its national oil company, Petronas.