Use of data reconciliation: A strategy for improving the accuracy in gas flow measurements

• DR is a powerful tool to reduce uncertainties associated with measurements.
• DR is a technique that improves the accuracy of process data by adjusting the measured values.
• The use of uncertainty analysis for the gas net management is the original achievement.
• Measurements with gross errors are identified and excluded, using uncertainty bands.
• Measurement redundancy in not an additional cost, it is a strategy for improving system accuracy.

The economic impact that results from the reliability of measurements associated with natural gas (flow rate and fluid properties) and caveats related to custody transfer contracts demands vigilant control of the net balance in the delivery systems. The methodology for data reconciliation has proved to be an effective tool to reduce uncertainties associated with measurements used in the calculations of the net balance in distribution networks such as gas pipelines. The intrinsic nature of the calculation algorithm, founded on the redundancy of measurements, qualifies the technique for increasing confidence in the measurement, thus reducing the individual uncertainty associated with each physical magnitude capable of affecting the measurement.This Brazilian gas pipeline study discusses the adequacy of the data reconciliation technique. The proposed technique proves to be very effective as it generates lower uncertainties than those obtained by traditional techniques: the level of 1% associated with the accountability of the unaccounted for gas was reduced to less than 0.3% when the data reconciliation methodology was used.