How do we extract oil from 5km depth and detect it underground?

[ENE]

Hello,
how we get oil from Earth at 5km how we get inform that there is oil inside it?

 

[Simon Bridge]

You mean: how does the petroleum geologist decide where to drill?
This is the subject of a college level course lasting years - what do you need the information for?
Have you seen:
http://science.howstuffworks.com/environmental/energy/oil-drilling2.htm
http://www.geomore.com/

 

[ENE]

Hello,
How petrol is taken out?

This is the subject of a college level course lasting years

I am from Electrical and electronics.

 

[Simon Bridge]

What have you done to try to find out for yourself?
Have you, for instance, googled for "how is petrol made" and found the following:
http://science.howstuffworks.com/environmental/energy/oil-refining2.htm
https://www.afpm.org/the-refinery-process/