This paper presents the orifice calibration results for nominal 15.24, 10.16, and 5.08-cm (6, 4, 2-in.) orifice meters conducted at the Chevron’s Sand Hills natural gas flow measurement facility in Crane, Texas. Over 200 test runs were collected in a field environment to study the accuracy of the orifice meters. Data were obtained at beta ratios ranging from 0.12 to 0.74 at the nominal conditions of 4576 kPa and 27°C (650 psig and 80°F) with a 0.57 specific gravity processed, pipeline quality natural gas. A bank of critical flow nozzles was used as the flow rate proving device to calibrate the orifice meters. Orifice discharge coefficients were computed with ANSI/API 2530-1985 (AGA3) and ISO 5167/ASME MFC-3M-1984 equations for every set of data points. The uncertainty of the calibration system was analyzed according to The American National Standard (ANSI/ASME MFC-2M-A1983). The 10.16 and 5.08-cm (4 and 2-in.) orifice discharge coefficients agreed with the ANSI and ISO standards within the estimated uncertainty level. However, the 15.24-cm (6-in.) meter deviated up to − 2 percent at a beta ratio of 0.74. With the orifice bore Reynolds numbers ranging from 1 to 9 million, the Sand Hills calibration data bridge the gap between the Ohio State water data at low Reynolds numbers and Chevron’s high Reynolds number test data taken at a larger test facility in Venice, Louisiana. The test results also successfully demonstrated that orifice meters can be accurately proved with critical flow nozzles under realistic field conditions.
Research of the metrological model of optic-thermal method of natural gas flow measurement
