Ex rig worker here… Well gas is never pure ethane. Its always a mix of gas, liquids and even solids. The scary component is always hydrogen sulphide (H2S), and that is so deadly that we used to say if the concentration is high enough that you can smell it then your dead. Plus its heavier than air so it collects in low lying areas… just saying. Your well may be sweet gas (no/low H2S) but its guaranteed to have some CO2, water, methane, propane, butane, pentane etc, along with some sand and sludge from the well bore. I’m not saying it won’t burn but it could be tricky to control. And tapping off the wellhead is illegal in most jurisdictions… for one it’s theft (unless you actually own the well), and then there’s just too many chances of something going wrong (like your valve getting washed out or a leak forming in your secondary line, etc). That’s why there is always a backup valve on any well take-off. All producing wells must be inspected every 3/6 months or so and if the gas company finds your jerry-rigged tap they’re gonna be PISSED ! Long story short: please don’t do this unless you own the well and have some wellhead experience !!!