The Oil Rig is created in water and gives the layer $10 p/m. It requieres the oil ship to go over an oil spot.
The oil rig is created when the player presses "N" while on top of an oil deposit in the water. This is a boat meaning it can only be made in water maps. The oil rig is the cheapest economic producer, costing $35 to make, producing 10 p/m, it is the 2nd tier of money source. Bypassing the standard Power Plant, and falling short of Nuclear Power Plant. Despite making the same amount of money as a Power Plant, it surpasses it by cost.
It is present in all Conquerors games, and costs the same amout. The oil ship is made in the docks (naval shipyard). In The Conquerors Mark II, it requires you to click "Build Oil Rig" and can glitch. It cannot attack and has a Sci-Fi look.