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Production of oil and natural gas can be classified into three main categories of hydrocarbon recovery. These categories include primary recovery (the first phase after a well is hooked up/put onstream), supplementary (secondary) recovery and enhanced recovery.

In primary recovery, the reservoir pressure (also referred to as the drive mechanism) forces oil or natural gas to the surface under natural flow. Some fields may have several producing horizons (productive hydrocarbon layers at various depths), each with varying pressures, oil types and other variable attributes that need separate production. These situations can be handled with either separate wells or with dual/multiple completions that can be set up in one well. The latter method is more complex and also more difficult to maintain. However, it is cheaper to install than resorting to second and third wells to produce the different horizons. In some oil wells, the natural flow deteriorates over time and is no longer sufficient to bring hydrocarbons to the surface, and thus it requires a "boost" to get the job done . In other wells, the natural flow is not sufficiently strong before production begins, and a "boost" is employed from day one to ensure adequate lift of hydrocarbons to the surface. To solve both of these problems, a form of artificial lift is required.

One form of artificial lift is called gas lift. It involves increasing the amount of gas produced with the oil by injecting gas into the flowing column (into the well) rather than into the reservoir. Gas lift uses special valves that are set up at various depths and then control the amount of gas entering the productive stream. The increase in the gas-to-oil ratio reduced the pressure needed to lift the oil to the surface. Pumping is another form of artificial lift and it includes three main types: 1) a beam or rod pump (sometimes referred to as a pumpjack); 2) a hydraulic pump; and 3) a submersible electric pump. The latter two types are installed within the well, itself.

Secondary recovery uses re-injection, a method whereby reservoir pressure is maintained by returning water or gas (naturally occurring reservoir fluids) to the producing zone via strategically drilled wells. These wells are known as injectors and are used to pump water or gas back into the producing formation. This acts to bolster the main (primary) drive as long as possible, to push more hydrocarbons to the surface. Both waterflooding and gas drive are known as secondary recovery techniques.

Enhanced recovery applies almost exclusively to oil production and involves injecting fluids into the reseroivr that are not normally present. The purpose is to alter the properties of the oil and produce a greater proportion of it. These methods are usually applied after primary and secondary techniques have been exhausted. Methods vary from injection of miscible fluids (as in carbon dixide or nitrogen) to complex polymers and steam (heating the remaining oil and making it less viscous and thus more pproducible). These methods can rais recovery by 10% to 20% under favorable conditions.