The oil is a mineral element different from the others, from its deposit is dynamic.
It does move. Is stored between the pores of the rocks or in the interstices of the sands, oppressed from the bottom up by the salt water on which floats, and from top to bottom by the gas that comes off. If it is motionless in the deposit, it is only for balance. Within the same oil there is dissolved gas which makes it more fluid, and allows, at the deposit temperature (more than 50%), drain easily through the ducts, often capillaries, which form in the sand or they pierce the rocks, first by gathering and accumulating in the “structure” (anticlinal, monoclinal, domo.), and then, When leave the perforated pit, the equilibrium of the deposit is broken.
Juegoslocos.com. (2008). Oil extraction. Retrieved from http://www.juegoslocos.com/extraccion-de-petroleo.html