methods and systems for testing a hydrocarbon well . real time monitoring of the flow stream discharging from a well is used to collect physical and electromagnetic characterization data on the flow stream . a data filter is used to exclude data points uncharacteristic of the true performance of the well at that time in the operational cycle of the well . a statistical evaluation during or after at least some data has been collected is used to determine when the data set meets an acceptable level of data quality . the filtering parameters are adjusted to improve future detection , correction , and filtering of uncharacteristic data . corrective transforms can be derived and applied to selected uncharacteristic data to recondition and retain the data . the filtered and completed data set is used to generate a hindsight determination of crude petroleum oil production output , including petroleum oil , water , and gas fractions and production rates .