Bertha Rogers Borehole

The Bertha Rogers Borehole is a former natural gas well in Burns Flat, Dill City, Oklahoma, US. Today plugged and abandoned, it was originally drilled by the Lone Star Producing Company as its oil-exploratory hole number 1–27 between October 25, 1972, and April 13, 1974, reaching a then world record terminal depth of.
During drilling, the well encountered enormous pressure – almost 25,000 psi. No commercial hydrocarbons were found before drilling hit a molten sulfur deposit, which solidified around the drill string, causing the drill pipe to twist-off and a loss of the bottom-hole assembly. The well was plugged back and as a natural gas producer.
According to publicly available well records from the Oklahoma Corporation Commission, the Bertha Rogers hole ceased production of natural gas in July 1997.
The Bertha Rogers hole was surpassed in 1979 by the Kola Superdeep Borehole dug by the USSR, which reached in 1989 and remains the deepest human-made hole on Earth as of 2026.