Fort Bend County produces substantial minerals. Throughout the county subterranean salt domes hold concentrated deposits of oil, gas, sulfur, and salt that made early development possible. Gulf Oil Company brought in the first commercially producing oil well in 1919 at Blue Ridge and, three years later, located another major field at Big Creek. Thompsons had a major oilfield in 1921. In 1926 Gulf discovered a major sulfur and gas deposit in Orchard; the Humble Oil Company (now ExxonMobil Corporation) opened a high-producing gas field near Katy in 1935 and later built a gas plant there that produced 450 million cubic feet of gas daily in the mid-1980s. Between 1954 and 1957 oil production in the county averaged 30,000 barrels a day, as compared to the 21,600 barrels a day in 1963. As demand for petroleum increased in the mid-1970s, developers managed to bring in forty new wells in 1976 and 1977, providing the county with $121 million from the sale of crude oil. Since that time a recession in the petroleum industry has caused development in the county to drop sharply. In 1976 the top three taxpayers in the county were, in order, Exxon, Gulf, and Houston Lighting and Power Company; in 1983 the top three taxpayers were Houston Lighting and Power, Exxon, and Utility Fuels. Gulf dropped to fourth place.