Petroinvestor.........29 Jan 2024 11:37
Yourself 'n OilmanJim may want to read this........! :)
" Further increases in helium content indicate that the drill bit is approaching a geothermal reservoir. For example, the background level may range from about 5 to about 12 ppm by volume, while faulted strata will have greater than about 12 ppm helium. Helium levels above 20 ppm, generally in the range of 70-1700 ppm, are found in fluids near geothermal reservoirs."
https://patents.google.com/patent/US4378055A/en
All the best (ya both welcome.......! :()
bingo......