Anadarko Petroleum has ventured beyond its original area of operation -- the Anadarko Basin -- to explore for, develop, produce, and market oil, natural gas, natural gas liquids, and related products worldwide. In 2015 the large independent company reported proved reserves (90% of which is located in the US) of 2.1 billion barrels of oil equivalent. Additional assets include coal, trona (natural soda ash), and other minerals. Anadarko operates a handful of gas-gathering systems in the Mid-Continent. Internationally, the company has substantial oil and gas interests in Algeria. It also has holdings in Brazil, China, Indonesia, Mozambique, and West Africa.