Company Profile

Multiphase Flow Meters: Subsea Oil, Gas, and Water Production Stream Profilers

Quick Answer: Multiphase flow meters measure oil, gas, and water flow rates in one subsea spool without a test separator. For production stream profiling in deepwater fields, a subsea multiphase meter typically handles pressures up to 690 bar and temperatures from minus 40 °C to 130 °C. Silver Automation Instruments supplies Coriolis mass flow meters, gas flow meters, and pressure transmitters for such subsea metering skids and well testing packages.

Most engineers skip the full PVT modeling step at first. In practice, you need real field numbers. A project in the Gulf of Guinea used a multiphase flow meter on a DN150 production line at 420 bar. The unit reported oil flow at 1,200 m3 per day, gas at 80,000 Sm3 per day, and water cut at 35 percent. That kind of data goes directly to the subsea control module over Modbus or 4-20 mA HART.

What a Subsea Multiphase Flow Meter Does

A subsea multiphase flow meter sits on a production jumper or manifold. It measures total mass flow and phase fractions without separating the well stream. The meter output includes oil rate, water rate, gas rate, gas volume fraction, and water liquid ratio. For a brownfield tieback in Southeast Asia, that means fewer well tests and faster allocation back to reserve calculations.

Here is the thing. Field conditions change faster than the original PVT report. A meter that works at 70 percent gas volume fraction may not read well at 95 percent gas volume fraction under slug flow. You need a flow computer update loop that pulls new gas compressibility and water salinity values after each well test.

Where Silver Automation Instruments Fits

Silver Automation Instruments is a flow meter manufacturer and supplier based in China. We provide Coriolis mass flow meters for single phase liquid measurement, ultrasonic flow meters for water and gas, vortex flow meters for steam and gas, and pressure transmitters for subsea skid monitoring. On a multiphase project, these instruments support the main profiler. A subsea skid builder in Malaysia ordered six Coriolis meters for chemical injection and MEG lines last year. The line sizes ranged from DN15 to DN50 and the pressure rating was 345 bar.

We have seen this on customer sites many times. A topside Coriolis meter on a separator liquid leg is not sealed against seawater corrosion. Then the housing paint fails within two years. For subsea use, specify 316L or duplex stainless steel wetted parts and a subsea connector rated for the same depth.

Key Parameters for Production Stream Profiling

When you send an inquiry for a subsea multiphase flow meter, include these numbers. Pressure rating is normally 345 bar or 690 bar depending on water depth and shut-in tubing pressure. Temperature range is often minus 20 °C to 130 °C. Line size may be DN80, DN100, or DN150. Gas volume fraction can swing from 0 to 98 percent during slug flow. Water liquid ratio can shift from 5 to 90 percent over field life. Accuracy targets for allocation are usually plus or minus 5 percent for liquid and plus or minus 10 percent for gas.

Deepwater fields in West Africa often require equipment rated for 1,500 m water depth. That means subsea connectors with a hydrostatic test at 1.1 times design pressure. A gas producer in Angola ordered pressure transmitters with Inconel 625 wetted parts for this reason.

Meter Selection for Subsea and Topside Skids

For separation packages and test lines, our Coriolis mass flow meter gives direct mass flow and density at 0.1 to 0.2 percent accuracy for single phase liquids. For flare gas or fuel gas loops, our vortex or thermal mass flow meters cover 0.5 to 2 million Sm3 per day. Our pressure transmitters with 4-20 mA HART connect to the subsea control module and provide pressure data at