Well then, it may be they have placed these warning signs around the tanks to keep folks from messing around with their stuff??? After all, who wants to be responsible for releasing "poisonous" gas, eh?
Thanks for the clinic on the horizontal drilling. Didn't know that.
There is some H2S in that gas but probably not enough to flare it. It is dissolved in the oil and saltwater in those tanks and can become concentrated enough that if you climbed up the ladder and stuck your head in the tank (like many people do just to see some oil), it could kill you deader than a door nail. It happens all of the time, especially to teens and drunkards out looking for something to do. Could you actually smell any of the gas while on the location? If not, then it is probably not a big deal.