Reservoir

Well property

A reservoir refers to a subsurface accumulation of hydrocarbons, such as crude oil and natural gas, contained within porous or fractured rock formations. These reservoirs form when organic material undergoes heat and pressure over millions of years, creating oil and gas that migrate into rock layers capable of storing them.

A reservoir is not a vast underground lake of oil but rather a network of tiny, connected pore spaces within rock, where the hydrocarbons are trapped by impermeable layers above and around them. The pore space is known as porosity which gives an indication of how much volume of hydrocarbon can be held in the rock, whereas the connectivity is know as permeability, which gives an indication of the ability for the hydrocarbon to flow through the rock.