What is an Oil Separation System?

Examples of Oil Separation Systems

Oil Separation System

Wells typically produce three elements: oil, gas, and water. Oil and gas producers use a combination of separation vessels, also called an “oil separation system,” to separate these elements. Three of the most common types of separation vessels are two-phase separators, three-phase separators, and heater treaters.

Three-Phase Separator

A three-phase separator separates process emulsion into three elements: oil, water, and gas. This type of separator is often called a free-water knockout (FWKO), because it is used to “knock out” any water, which can cause problems such as corrosion. A mechanical dump valve processes this water out, and it is either recycled or sent for disposal. Three-phase separators come in vertical and horizontal orientations.

Two-Phase Separator

A two-phase separator separates the production emulsion into two elements: gas and liquid. A two-phase separator can be horizontal, vertical, or spherical. The liquid (oil and water mixture) leaves the vessel at the bottom through a liquid level controller or mechanical dump valve. The gas leaves the vessel at the top, passing through a mist extractor to remove the small liquid droplets in the gas.

Heater Treater

When fluid enters a  two-phase or three-phase separator, separation begins naturally due to the different specific gravities of the elements. A heater treater, as the name implies, introduces heat in order to accelerate this separation process.  

Heater Treaters contain an internal firetube, which uses supply gas to heat the produced fluid inside the vessel. They use a low pressure control valve to regulate the temperature of the fluid. Heater treaters come in horizontal or vertical orientations.


If you’d like more information about how Kimray valves and control products can provide control on your separator or heater treater, contact your local Kimray store or authorized distributor.

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Breck Swigart serves as Kimray’s Director of Product Support.