Multiphase and wet gas flowmeters (MFMs) are becoming drastically cheaper, allowing the capability to be used by most of the oil and gas companies today. If the CAPEX can be reduced, the main question about the reliability and the capability of such equipment to provide accurate data and to perform correctly compared to previous technology (usually a separation-based system) remains. The unrealistic specification of multiphase manufacturers made in the past led to suspicion of such products by oil and gas companies. Additionally, the reluctance of using MFMs could be due to a number of technologies that require significant effort to have a proper understanding of the device.

The buying process very often leads to some form of comparison test made either before delivery (usually tested in a third-party facility), or later in the field regularly or spot check against standard equipment (separators, tanks or any other trending devices). This fair initiative to understand the real performance usually leads to more questions about what/how/where/when to compare and are also incredibly important. Last but not least, what should define the "PASS/FAIL" criteria? It should also be noted that limited test envelopes (flow conditions) may not reflect the entire performance of the meter. Therefore, either additional measurements or statistic elements should be used to establish the actual statement or meter performance.

It is incredible to see, today, in the billions of dollar oil and gas business that most of the systems are reporting flow rates without any information about the measurement uncertainty, this leads to the belief that the production is entirely known. Unfortunately, people working in allocation are the first to face this challenge and to reconcile the data. On the other hand, the top-class MPFMs are providing uncertainty on measurement, which is as good as, if not better than, some of the standard equipment that is used and so the uncertainty of both devices needs to be thoroughly taken into account in these comparisons to make allocation fair and indisputable.

The paper will embrace these comparison tests, the author has repeatedly faced such cases over the years and wishes to bring to light the relevant work that needs to be done before, during, and after the tests to make it conclusive. We expect to provide some practical statements which will progress and help all parties involved in these comparison tests where the presence of a third party (being impartial and independent) can ensure there is no bias in the overall statement.

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