Types of Oil Well Separators: Horizontal, Vertical, and Spherical

The fluids produced from oil wells are normally complex mixtures of hundreds of different compounds. A typical oil well stream is a high-velocity, turbulent, constantly expanding mixture of gases and hydrocarbon liquids, intimately mixed with water vapor, free water, and sometimes solids. Three types of separators are generally available from manufacturers. Selection of separator type is based on several factors including characteristics of production steam to be treated, floor space availability at the facility site, transportation, and cost.

Horizontal separator:

Horizontal separators are usually the first choice because of their low costs. Horizontal separators are almost widely used for high-GOR well streams, foaming well streams, or liquid-liquid separation

Horizontal separators are easier to skid-mount and service and require less piping for field connections. In horizontal separators, gas flows horizontally while liquid droplets fall toward the liquid surface. The moisture gas flows in the baffle surface and forms a liquid film that is drained away to the liquid section of the separator. The liquid-level control placement is more critical in a horizontal separator than in a vertical separator because of limited surge space.

Vertical separator:

Vertical separators are often used to treat low to intermediate GOR well streams and streams with relatively large slugs of liquid. They handle greater slugs of liquid without carryover to the gas outlet, and the action of the liquid-level control is not as critical. Vertical separators occupy less floor space, which is important for facility sites such as those on offshore platforms where space is limited

Because of the large vertical distance between the liquid level and the gas outlet, the chance for liquid to re-vaporize into the gas phase is limited. However, because of the natural upward flow of gas in a vertical separator against the falling droplets of liquid, adequate separator diameter is required. Vertical separators are more costly to fabricate and ship in skid-mounted assemblies.

Spherical separator:

Spherical separators offer an inexpensive and compact means of separation arrangement. Because of their compact configurations, these types of separators have a very limited surge space and liquid-settling section. The placement and action of the liquid-level control in this type of separator is more critical