From what I understand, the gas is not flowing out of a pipe at ground level; the leak is deep underground and it is diffusing into rock and coming up over a wide area. It's not clear that combustion could be sustained in that configuration. I have as much oil/gas industry experience as rube goldberg, but I suppose if they put a huge upside-down funnel over the area maybe they could collect it and light the top, but I have no idea whether the radius of that funnel would have to be 10m or 10km.
I feel a good solution would be to implement a carbon tax, and an unburnt methane tax at the greenhouse equivalent, and start charging the company the estimated leak. I imagine their engineers would become more motivated.
http://www.laweekly.com/news/what-went-wrong-at-porter-ranch... has a very clear diagram of what's happening. The inner casing of the well sprang a leak. The gas is blowing all the way back down the outer casing of the well, then exiting adjacent to the casing. So, while the leak is concentrated to an area directly adjacent to the well, it's not a matter of simply capping the pipe.
perhaps more acurately, it would motivate the budget holders... engineers work with the resources their company allocates. a large tax/fine would certainly help incentivise the right kind of response. although, the fine should be large enough to have prompted the correct behaviour in 1979!
