It is invisible, and has no smell. It burns very easily. Also, gas pipelines are expensive to build. Methane has no smell . The gas companies put a little bit of metcaptan into the natural gas so we can smell it.
Sour gas is gas that has hydrogen sulphide in it.
About nine-tenths of Canada's sour gas is in Alberta. If you haven't smelled a rotten egg, think of the last time your toilet backed up. A little bit isn't so bad, though. If you've gone to the hot springs in Banff, you've noticed the smell. Sour Gas is dangerous.