GATHERING
Smaller diameter pipelines known as gathering systems directly connect to producers’ wellheads or production facilities. These pipelines transport untreated oil or gas to a central location, where it is treated and processed, if necessary. Produced water is also gathered and often accounts for the largest byproduct stream associated with onshore oil and natural gas production.

STABILIZATION
The stabilization process for natural gas separates heavier hydrocarbons from the lighter components by using a distillation process, adding heat, or by reducing the pressure and allowing the more volatile components to flash from the liquid phase to the gas phase.
The stabilization process for crude oil ensures the crude oil meets downstream vapor pressure specifications. Crude oil delivery points, like terminals, storage facilities, pipelines, and refineries, often have specific requirements for vapor pressure and temperature, and for the amount of sediment and water that can be contained in any crude oil delivered to them.
 
COMPRESSION
Natural gas is compressed to a desired higher pressure to enable it to be gathered more efficiently and delivered into a higher pressure system, processing plant, or pipeline. Since wells produce at progressively lower field pressures as they deplete, field compression is needed to maintain throughput across the gathering system