doodlebugging

American slang for using dowsing rods, divining rods, or other pseudoscientific instruments to try to locate underground oil or gas deposits. The term comes from the oil industry of the early twentieth century, when 'doodlebug' referred to any unscientific or dubious prospecting method. Wildcat oil drillers and petroleum speculators who relied on such methods were met with equal parts amusement and suspicion by those who preferred geological surveys.

(US) dowsing in search of petroleum.