What shape is the oil liquid below ground? is it like a lake or river?

Question

What shape is the oil liquid below ground? is it like a lake or river?

Answer 1

It is found in various places.  Sometimes it fills the pore space in a sand or gravel.  Sometimes it fills a cave or void. It can be trapped in a number of ways.  A typical field is a large fold called an anticline.  It forms a shape kind of like an umbrella.  As oil moves upwards, it encounters a layer such as a clay which hinders its upward movement and it moves toward the top of the umbrella shaped structure where it is trapped.  Picture holding an umbrella under water.  If bubbles come up and encounter the umbrella, they will move up till they are trapped at the point.  It is a similar process with oil.  You use seismic studies to find these areas and you drill into them to see if you strike black gold.