A reservoir refers to a subsurface rock formation that contains a significant amount of oil and/or natural gas. The reservoir is typically located several thousand feet below the Earth’s surface and is composed of porous and permeable rock layers, which allow for the accumulation and flow of hydrocarbons. The hydrocarbons in the reservoir are trapped by impermeable rock layers or structures, such as faults or salt domes, that prevent their upward migration to the surface. Reservoirs can vary in size, shape, and depth, and they are typically identified through geological and geophysical exploration and analysis. Once a reservoir has been discovered, various techniques are used to extract the hydrocarbons, including drilling, well stimulation, and enhanced oil recovery methods.