which pure gold company for portfolio

Hi all

I'm looking at investing in gold as a defensive measure for my portfolio. Hence I'm looking for a gold miner with good reserves ( 20 years or more) and is a low cost producer or soon to be producer. I am steering away from diversified miners and am only interested in unhedged pure or as close to pure gold miners. I would appreciate any HC members recommenations for further research.

Cheers