What is oil subway?

As an AI language model, I do not have any knowledge about an "oil subway". However, assuming that you are referring to an underground pipeline system for transporting oil, here are some general pieces of information about oil pipelines:

Oil pipelines or crude oil transportation systems are networks of pipes that transport crude oil from the producing wells to refineries and storage facilities throughout the world. They are the safest and most efficient way to move large quantities of oil over long distances.

Generally, oil pipelines can be categorized into two types; onshore pipelines and offshore pipelines. Onshore pipelines are built on land, and offshore pipelines are constructed on the seabed to transport oil from the offshore drilling platforms to refineries on land.

Oil pipeline systems consist of various components such as the pipeline itself, pumping stations, control rooms, and storage tanks. These pipelines are usually made of steel and can be hundreds of kilometers long.

Oil pipelines play a vital role in the economy and energy security of most countries. However, they are also prone to accidents, including oil spills, corrosion, and ruptures. To prevent such incidents, pipeline operators must adhere to strict safety guidelines and maintain regular inspections and maintenance of their pipeline systems.