Ok, so we know that oil is going to be a minable resource in the game. We also know that Kyren has implemented a fairly sophisticated liquid physics system, which allows for liquids to be under pressure and react accordingly. From there, it shouldn't be difficult to allow for some very realistic oil extraction. To simplify somewhat, you'd Locate an oil deposit underground. Somehow create a large-ish water reservoir above the oil deposit, perhaps by diverting a nearby lake. Drill a hole or place a pipe down to the oil deposit. This pipe is to allow the oil to rise out. Pump water down a pipe or tunnel into the oil deposit. The water being pumped down increases the pressure in the oil well, so that oil starts rising out of the first pipe. I wouldn't mind if there were other ways to extract the oil, so long as the above remains a viable option. To make life somewhat easier, you could actually have pre-pressurised oil reservoirs, that spew out say half their oil simply by drilling a hole to them. To get the remaining oil you'd need to start pumping down water.
Indeed. However, on some planets, the liquids that classify as water could be as light/lighter than the oil, or the oil like substance could be very dense!
