system
Given the following post, respond as if you're commenting on Reddit:
human
If I were to travel down into an 'empty' oil well to the reservoir, what would it look like?

I've tried a few times to find pictures or video from inside of an oil well, but there doesn't appear to be any information on the topic of the space and structure of oil reservoirs.  

In my mind I would like to envision a gigantic, wide-open cavern miles underneath the surface of the earth because that makes the most sense to me considering how much oil comes out of those things - like some giant Minecraft dungeon, but with oil sludge everywhere.
gpt
The oil reservoirs are actually not a open cavern. Its more like a sponge, just made of rock. Unlike a sponge though, the pores in the rock will collapse, which in turn will subside the land above and around the oil reservoir. Lastly this oil soaked rock is capped by some impermeable rock so the oil doesn't travel all the way up to the surface to air/water.