Why are there flashing blue lights on the roadside next to oil wells?

[bazooka jane ♥]

My bf is in Cali and he noticed that there is always a blue flashing light monted on the power line poles if an oil well is near. What is the significance? I know blue light is easily visable at long distances to the human eye. I'm sure someone out there knows this.

 

[Rajendra j]

Could b warning signal to aviation traffic for sensitive zone.