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The Lone Star Producing Co. 1–27 Bertha Rogers hole or well was an oil-exploratory hole drilled in Washita County, Oklahoma in 1974, and was formerly the world's deepest hole until in 1979 surpassed by the Kola Superdeep Borehole, dug by the USSR.
It took Lone Star a little over a year and a half to reach 31,441 feet (9,583 m), a depth of almost six miles. During drilling, the well encountered enormous pressure – almost 25,000 psi (172,369 kPa). No commercial hydrocarbons were found before drilling hit a molten sulfur deposit (which melted the drill bit). The well was plugged back and completed in the Granite Wash from 11,000 to 13.200 feet as a natural gas producer.