Well...like everything, there's more to it than that.
There are different types of flare booms/towers. Every one I've seen (except the subsea flares) are at or *above* the heliport level.
Lit flare booms can creat an enormous amount of radiant heat that you can feel in the helicopter, even if you are not directly downwind from them and even if the actual flare outlet is high above the heliport.
Unlit flares are the problem. When the platforms "shuts-in," excess gas in the lines is vented overboard. This happens more than you might think. You can't see the gas (actually, you can if you look very, very closely and if the pressure is high enough but by then it's probably too late). If flare gas is ingested into your engine inlet, it is unregulated and, added to the ambient are it can enrichen the fuel mixture to a point where you'd have an exeedance of some sort (overspeed, overtorque or overtemp). So you have to be careful. Don't fly directly downwind of flare towers/booms.
Not every platform in the GOM has a "Flaring Gas!" light although it would be nice. Actually, it would be nice if there was *any* kind of standarization in the Gulf. The platform I lived on for nine years did have a flashing light on the flare tower. You could really only notice it if you were sitting right on the heliport.