This paper presents two years of operating experience and field evaluation of a 3” Roxar (MFI model) multiphase meter used for continuous production testing in a highly sour field environment where the hydrogen sulfide concentration in the production gas exceeds 10 mole percent. The MFI meter was installed and commissioned in February 2001 at a well site in Tengiz Field, Kazakhstan. The multiphase meter’s performance was evaluated by comparing measured flow rates with a three-phase test separator located at a meter station approximately one kilometer downstream of the well site. The oil and gas flow rates from the MFI multiphase meter were found to be in reasonable agreement with the test separator flow rates measured by vortex meters. The water cut measurement error was somewhat higher than Roxar’s multiphase meter’s accuracy specification. Since the water production in Tengiz is very low, the water cut measurement became an indicator of the reliability of the MFI meter. During the last meter repair in November of 2002, the ceramic sleeves inside the microwave sensor were found to be broken and surrounded by a layer of iron sulfide scale. The water cut measurement returned to the baseline value after the broken sleeves were replaced. In conclusion, two years of well testing experience at Tengiz Field suggested that the MFI multiphase meter’s oil and gas flow rate measurements agreed reasonably well with test separator results when it is functioning properly. Its poor reliability in water cut measurement was probably caused by gradual degradation of the ceramic sleeves inside the water cut sensor which might be exacerbated to some extent by the formation of iron sulfide scale in the sour field environment.
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