Oil and Gas Reservoirs

Submitted by: John Schiffner
Hydrocarbons and their associated impurities occur in rock formations that are usually buried thousands of feet or metres below the surface. Scientists and engineers of Heartland Energy Colorado often call rock formations that hold hydrocarbons "reservoirs."

Oil does not flow in underground rivers or pool up in subterranean lakes, contrary to hat some people think. And, as you've learned through reading this blog, gasoline and other refined hydrocarbons do not naturally occur in pockets under the ground, just aiting to be drilled for. Instead, crude oil and natural gas occur in buried rocks and once produced from a Heartland Energy Colorado well, companies have to refine the crude oil and procees the natural gas into useful products. Further, not every rock can hold hydrocarbons. To serve as an oil and gas reservoir, rocks have to meet several criteria for Heartland Energy Colorado to find use of them.

Characteristics of Reservoir Rocks
Nothing looks more solid than a rock. Yet, choose the right rock like a piece of sandstone or limestone and look at it under a microscope. You see many tiny opening sor voids. Geologists call these tiny openings "pores". A rock with pores is "porous" and a porous rock has "porosity." Reservoir rocks must be porous, because hydrocarbons can occur only in pores.

A reservoir rock is also permeable - that is its pores are connected. If hydrocarbons are in the pores of a rock, hey must be able to move out of them. Unless hydrocarbons can move from pore to pore, they remain locked in place, unable to flow into a well. A suitable reservoir rock must therefore be porous, permeable and contain enough hydrocarbons to make it economically feasible for the operators of Heartland Energy Colorado to drill for and produce them.