Three-Phase Operation

Well production contains gas dissolved in oil plus formation water. The separator provides residence time allowing gas to bubble out and rise, oil to accumulate in middle layer, and water to settle to bottom. Level controls maintain oil-water interface and total liquid level ensuring clean phase separation.

Vessel Configuration

Horizontal cylinder with gas separation section at inlet end, oil collection zone in middle, water settling section at far end. Internal weirs control liquid depths. Inlet diverter spreads flow preventing turbulence that would mix phases. Coalescing plates enhance oil-water separation by providing surface area where small droplets combine and grow.

Operating Pressure

Design pressure matches wellhead flowing pressure typically 100-1500 psig. Higher pressure increases gas solubility requiring larger vessel volume and longer retention time. Lower pressure simplifies separation but may restrict well production. Pressure selection balances separation efficiency versus production rate.

Retention Time

Gas disengagement happens quickly - seconds to minutes. Oil-water separation needs more time - 5 to 30 minutes depending on viscosity, temperature, and density difference. Viscous oil or small density difference between oil and water requires longer retention and larger vessels.

Material Selection

Carbon steel works for sweet production. Sour service with H₂S needs NACE materials and welding procedures preventing sulfide stress cracking. Internal components resist corrosion from produced water containing salts, acids, and bacteria. Coatings extend life in corrosive environments.

Applications

Production facilities separating crude oil with gas and water, enhanced recovery operations handling injection water returns, heavy oil production with steam or polymer floods, offshore platforms with space constraints, and any oil production requiring three-phase separation.

Interface Control

Interface level instruments detect oil-water boundary using capacitance, displacer, or float technology. Controller modulates water dump valve maintaining interface position. Oil level control manages total liquid height. Proper control prevents water in oil outlet or oil loss through water outlet.

Water Handling

Produced water contains oil, salts, and solids requiring treatment before disposal or reinjection. Clean separation minimizes oil content simplifying downstream treatment. Water dumps to tanks or treatment systems. BS&W monitoring verifies separation quality.

Oil Quality

Target oil outlet typically contains under 1-3% water meeting pipeline specifications or further treating requirements. Some production needs only rough separation before dehydration equipment. Others require clean oil directly to sales. Separator design matches downstream requirements.

Performance Factors

Temperature affects viscosity and density difference - warmer improves separation. Emulsions from surfactants or mixing require chemical treatment and longer retention. Gas content affects liquid level control. Design accounts for fluid properties and production chemistry.

Construction Standards

Design per ASME Section VIII for pressure service or API 12J for production equipment. Materials suitable for crude oil, gas, and produced water. Relief sizing per API 521. Complete documentation with capacity calculations and material specifications.

ERGIL three-phase separators provide reliable oil, gas, and water separation in crude oil production across diverse field conditions and fluid properties.