When fluids flow up from a well, they arrive as a mixed stream of gas, oil and water. The first job at surface is to split that stream into its components. This is done by separators and, where emulsions form, by heater-treaters — the foundational equipment of every production facility.
A surface vessel that splits the produced stream into phases. A three-phase separator divides the flow into gas, oil and water — the first step of surface processing.
How a three-phase separator works
A three-phase separator divides the produced stream into gas, oil and water. Inside the vessel, gas breaks out and exits from the top, while the heavier liquids fall and settle by density. Because oil is lighter than water, the two liquids stratify, and oil and water exit separately through their own outlets. This is typically the first surface processing step after fluids leave the well.
In a three-phase separator, gas exits from the top while oil and water settle by density and leave through separate outlets — the first stage of surface processing.
Heater-treaters and emulsions
Sometimes oil and water do not separate cleanly because they form a stable emulsion — water droplets suspended in oil. A heater-treater resolves this by applying heat (and sometimes an electric field or chemicals) to break the emulsion, allowing the water to drop out so clean oil can move on to storage. Heater-treaters are therefore essential where produced fluids are difficult to separate.
Together, separators and treaters condition produced fluids so that oil is clean enough for sale, gas is routed for processing, and water is sent for disposal or reuse. They feed directly into the tank battery where oil is stored before sale.
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Frequently asked
It splits the produced stream into gas, oil and water. Gas exits from the top, while oil and water settle by density and leave through separate outlets.
A heater-treater breaks stable oil-water emulsions using heat — and sometimes electricity or chemicals — so that water drops out and clean oil can move to storage.
Separation is the first surface processing step after fluids leave the well, conditioning the stream before oil is stored, gas is processed and water is disposed of.