Does anyone know what the purpose of oil is in the Earth in it's natural state?

I was just curious about what oil might be doing in the Earth in the first place %26amp; what it's relationship to other elements or natural events might be. Does it have any relationship to earthquakes for instance?Does anyone know what the purpose of oil is in the Earth in it's natural state?
I'm not sure what you mean by ';purpose'; - nothing on Earth has any intended purpose, since nothing was created for any particular reason. As for oil, the prevailing theory is that it is the remnants of organic matter that, thanks to the effect of pressure and time, has decayed down into a sludgy mix of hydrocarbons. Oil deposits form conditional on geology, but they aren't created by tectonic or geological processes - they are simply buried plant or animal matter - so they do not have to be found near fault lines and bear no relation to earthquakes.Does anyone know what the purpose of oil is in the Earth in it's natural state?
Our fossil fuel is created by plants and is part of the air recycling. The CO2 is taken in by plants and the plant gives us back the O2 but the plants hold on to the C. The C is in the body and leaves and when the leaves fall off the wash down the rivers to the delta where it will deteriorate into oil,gas,and coal. It has been doing this for millions of years .