There are lots of oil wells pumping 24/7 in LA right now. Many are actually in buildings so that you can not see them.
There was so much oil in the LA area that it was leaking out of the ground. The La Prea Tar Pits is an example of this.
Excellent point, Butcher. I was surprised to learn there are productive oil derricks all over Los Angeles, even dotted in residential areas. Nowadays they’re often camouflaged, as you point out. (My dad used to call Polish carpenters “wood butchers.”)