system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How can we suck out oil from the ground without it caving in those areas?
gpt
Mostly, oil-bearing rocks are somewhat spongy rock, not underground pools. The oil may be under pressure, in which case, drilling into it will reduce the pressure, but not to zero. In other cases, drillers have to pump water or gas into the rock to extract the oil, which maintains the pressure.