Multiphase Flow Meters: Experience and Assessment in PDO
Authors: Khamis Busaidi , Haridas Bhaskaran 
Published: December 2007

The use of MultiPhase Flow Meters (MPFM) in PDO has great potential economic impact on oil and gas field developments. This is the reason for the drive in PDO for using MPFM technology instead of conventional test separators. Most of the commercially available in-line MPFM's perform well at low and moderate GVF's (&lt;80%). In order to assess the uncertainty of the MPFM's at high GVF flow regimes and high water-cut in the liquid flows, it was decided to carry out a detail accuracy tests of some of those commercially available multiphase flow meters.

Seven multiphase flow meters were proposed for the test; i.e. Schlumberger VX, Roxar, Daniel (Megra), Halliburton (FlowSys), Haimo, Axon, and Premier Instruments (GLCC).

All the seven vendors were invited to participate in the test. Roxar declined, while Axon and Premier requested to postponement of the test. The remaining four vendors accepted.the invitation for the test.

In order to evaluate the performance of these multiphase meters accurately to the live oilfield conditions, it was decided to carry out the test in a live crude facility with higher turn down ratio and known accurate reference measurements.

The test was conducted in DOD Multiphase Flow Facility located in Daqing Oilfield, Daqing City, China. This facility was conceptually designed by National Engineering Laboratory (NEL), Glasgow, UK. It was approved by China

National Measurement Institute and China National Petroleum Corporation (CNPC), the foremost authority in Measurement and Control in China.

The test was carried out over wide flow range, with oil flow rates up to 1200 m3/d, a full water-cut range of 0 to 100% and a maximum gas flow rate of 28,000 m3/d (actual). During the tests, the actual GVF of the multi-phase stream could be varied between 0% to 99% covering all the possible flow regimes. The behaviour of the meters were also assessed with disturbing flow condition thus simulating a slugging or surging flow from wells.

The criteria set by PDO for this test was that the meter will have to prove that it works with the following accuracy; Net Oil flow of +/−10% relative, Gas Flow of +/−10% relative and Water cut of +/−2% absolute.

The test showed that only two meters have met the above criteria. The Haimo meter showed accuracy +/−10 % relative on the net oil flow rate, water flow rate and gas flow rate and +/− 2% absolute on the water cut measurement over full range of 0 to 99% GVF. The Schlumberger meter showed accuracy +/−10 % relative on the net oil flow rate, water flow rate and gas flow rate and +/− 2% absolute on the water cut measurement over 20 to 85% GVF. Outside this GVF range, the accuracy in the water cut of the Schlumberger meter was within +/− 5% absolute. The accuracy of the other meters was found to be outside the above criteria. The results are discussed in details in this paper.

The repeatability of the reference measurements of the DOD facility was assessed. This was found to be +/−1% relative error for liquid and gas flow and +/−0.5% absolute for water cut measurements.