How are coal and petroleum found? Describe the major oilfield and coalfield in the world?
I can’t really speak for coal, but as for petroleum I can. Geologist and Geophysicists look for geological formations that have the possibility of containing petroleum. We use seismic waves to map geological structures beneath the earth. Once a geological formation is found that has a possibility of containing petroleum, an exploration well is drilled. Then a series of tool are run into the well to measure several different formation properties (called logging). The readouts of the logs shows whether or not the actually is petroleum there. The major oil fields in the world are Gwahar in Saudi Arabia, Sakahlin Island in Russia, Kashigan in Kazakstan.
