Page 122 - Intelligent Digital Oil And Gas Fields

Data Filtering and Conditioning 89

of reconciliation are that it can only solve mismatches when there is pressure
fluctuation, mass or density variations, water cut changes, temperature
change, etc. Reconciliation cannot be used when an abnormal situation
occurs, such as the pipeline leakage, pump wear, pump blockage, equipment
failure, bottleneck in pipeline, etc., which must be attended to immediately.

3.2.5.1 Reconciliation Method: Example
An oil well is equipped with a Coriolis meter measuring in real-time liquid
rate (Well C). The Coriolis meter has a tolerance of 10%; the average liquid
rate in Well C is 850bbl/d; the total uncertainty is 85bbl/d. Well B is pro-
ducing 1300bbl/d using a trained virtual meter. The production engineer
mentions that the confidence interval is 6% because physics-based calibra-
tion was used to calibrate the virtual metering; therefore, the total uncer-
tainty is 78bbl/d. Both wells are measured to a portal-mobile MPFM,
which has a tolerance of 3%. The total sum of independent points is
2150bbl/d, but the MPFM measures 2265bbl/d (+115bbl/d above the
manual sum). Fig. 3.4 describes the wells.
The method describes:
Uncertainty calculation (U t ): U t ¼y (1 %Tol) .

Fig. 3.4 Data reconciliation method with three points of measurement: coriolis, virtual,
and multiphase flowmeters.