Subject: Effects of carbonic acid on a Natural Gas Storage field

I work in a Natural Gas storage facility. We store Methane gas in a 
depleted field. The composition of the gas is 95-98% methane;.5% N2;1.7% 
CO2; a BTU value around 1000 and specific gravity of .5 to .6. We run a 
pressure of anywhere from 500psi to 3000psi it varies due to withdrawl or 
injecting in facility. The question I have is my Boss says that when our 
CO2 percentage gets over 2% that it is detramental to our facility. He 
says it creates Carbonic acid and it will eat the tubing strings (pipe). 
But what I have read is that Carbonic acid is very weak, so how could it 
be so bad? Could you better explain this for me and also tell me at what 
percentage and pressure that Carbonic acid would cause damage? Also if 
there is any literature on this subject. Thank You in advance for any help.
 

Re: Effects of carbonic acid on a Natural Gas Storage field