Question

how is petroleum formed and where is it found?

Answer 1

1) Most of the petroleum occurrences in India are associated with anticlines and fault traps in the rock formations of the tertiary age.
2) In regions of folding, anticlines or domes, it occurs where oil is trapped in the crest of the upfold.
3) The oil bearing layer is a porous limestone or sandstone through which oil may flow.
4) The oil is prevented from rising or sinking by intervening non-porous layers.
5) Petroleum is also found in fault traps between porous and non-porous rocks.
6) Gas, being lighter usually occurs above the oil.

Digboi in Assam, Bombay high in Mumbai, Gujarat, and Rajasthan have most of the petroleum deposits.