A separator is a piece of equipment used in the oil and gas industry to separate a mixture of oil, gas, and water into their individual phases. The two main categories of separators are two-phase and three-phase separators. Two-phase separators are used to separate well fluids into the liquid and gaseous fractions. A three-phase separator, on the other hand, separates well fluids into the water, oil, and gaseous components. Multi-phase separator uses gravity to separate produced well fluid. Installation of these vessels occurs near the wellhead, and they come in horizontal and vertical configurations.

The separation process begins with the mixture entering the inlet of the separator. The first phase to separate is the gas, which rises to the top of the separator due to its lower density. The gas is then directed out through a gas outlet line. The remaining mixture of oil and water flows down to the lower part of the separator, where further separation takes place. The oil, being less dense than water, floats on top and is collected through an oil outlet line. The water, being denser, settles at the bottom and is removed through a water outlet line.

The separators are designed to handle the varied flow rates and compositions of the three phases and ensure efficient separation. It typically consists of a vessel with internals such as mist elimination and coalescing devices that promote the separation of the individual phases.

Multi-phase separators are essential in the oil and gas industry to maximize production efficiency and ensure the quality of the extracted oil and gas. They help in reducing the amount of water and gas content in the oil, making it easier to transport and refine.