My bad yes you are right FHC that methane gas is generated by...

My bad yes you are right FHC that methane gas is generated by bacteria and helium is by uranium decaying (guess i mistook the 50yr non-stop helium flowrate at same grade as unlimited (50 year is a unbelievable long time already isn't it) because of the functioning of bacteria underground from memory for some reason). I rewatched the below video and it's just fascinating even watched it several times before:

https://www.renergen.co.za/the-magic-of-helium-carte-blanche-m-net/

From 4:30 mark regarding how the methane and helium are generated in this crater region. And from some 6:00 mark: "... usually gas wells last for around 15 years but gas wells that were drilled here in 1950s and 1960s are still producing helium bearing gas...", Stefano continues at 6:15 mark: "...this well alone is still blowing at the same rate today as that it was back in 1972...this thing has produced over 200,000kg of helium and there has NOT been a decline in the concentration of helium..."