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ConocoPhilips / Rosneft “Polar Lights” Field

Due to a mass balance issue, a natural gas station operator suspected a 12" 0.496 beta orifice meter was giving erroneous readings. A 3rd party auditor was called. The first reaction of the auditor was to install a clamp-on ultrasonic meter as a check meter. However, the pressure was low and the clamp-on ultrasonic meter output was intermittent and its data scattered. Hence, little information was ascertained from the clamp-on ultrasonic meter. The auditor then installed Prognosis on the orifice meter. Prognosis showed the orifice meter had a problem, and that the problem was a physical problem and not instrumentation. Further Prognosis pattern recognition identified wet gas flow. The plate was removed and found to be coated with water. It was estimated that gas flow bias was in the order of +2%.