Gas injection pump cannot be placed on top of existing deposit

I dumped 6 layers of limestone where I wanted to inject some CO2, and when the project was done, I couldn't build the injection pumps there because it is where my initial crude oil deposit used to be. That's now exhausted, but I still can't build the injection pump. That seems like a bug, but if it's intended, it should be communicated better.

Maybe change the title to "... on top of emptied oil deposit"