Verification of Flare Measurements at Upstream Oil and Gas Facilities in Comparison to Visible Infrared Imaging Radiometer Suite Data

Abstract The main objective of this paper is to analyze and validate the measurement of flaring volumes at oil and gas upstream facilities using the metered flare volume data, comparing these measurements to the annual gas flared volumes estimated by Visible Infrared Imaging Radiometer Suite (VIIRS) Nightfire. Additionally, it assesses the accuracy of VIIRS Nightfire data in quantifying gas flared volumes at four flaring sites in Oman, thus confirm the reliability and effectiveness of VIIRS Nightfire as a tool for monitoring gas flaring activities. Flare management is a key pillar in PDO’s Decarbonisation strategy, significant efforts were placed to reduce company’s flaring emissions and ensuring flare measurement accuracy and verification. PDO submits its annual total and routine flaring volumes to the World Bank as part of the Zero Routine Flaring Initiative, during the years we have noticed discrepancies between the figures submitted by PDO and the data issues in the World bank report via their website. Thus, a study was conducted between PDO and the World Bank to verify the discrepancies using the measured flared volume data versus the VIIRS Nightfire method. This study conducted an in-depth analysis of four facilities in collaboration with Petroleum Development Oman (PDO) and The World Bank through the Colorado School of Mines. Four PDO facilities were selected for an in-depth analysis due to noticeable data discrepancies. The analysis included 1-minute interval high-frequency metering data for AP/LP/HP flares and flow meter readings with the World Bank. Coordinates (easting/northing) were analyzed to confirm proximities and precise locations. Two sets of satellite calibration methods were used by the World Bank and Colorado School of Mines to evaluate the accuracy of VIIRS Nightfire data using Cedigaz calibration and John Zink calibration to establish a relationship between instantaneous flow rate (FR) in million of cubic meters per day to align with metered data units and the radiative heat (RH) to flared volume (Q) as detected from satellite for a gas flare, empirical calibration is necessary. John Zink calibration demonstrated better accuracy than Cedigaz calibration for small flare volumes. Discrepancies were attributed to limited data availability, data synchronization issues, and metering quality concerns. These findings underscore the importance of calibration accuracy, data synchronization, and metering quality in improving flaring volume estimation and alignment between ground-based and satellite-based measurements. This paper will compare the satellite derived estimates from VIIRS Nightfire with ground-based metered measurements, thus confirming the reliability and effectiveness of VIIRS Nightfire as a tool for monitoring gas flaring activities. This comparison will provide valuable insights into the potential of VIIRS Nightfire for more widespread application in gas flaring surveillance and emissions reporting. Facility-Specific Findings suspected metering issues identified based on Cedigaz and John Zink calibrations, warranting further investigation in facility ‘A’, whereas, discrepancies were linked to inadequate satellite readings due to low flow rates in facility ‘B’. The deep-dive analysis with the World Bank yielded lower detection limits of VIIRS sensors for facility ‘B’ and the World Bank agreed to correct its estimates using John Zink calibration, subsequently the corrections shall be implemented to all applicable facilities with low flowrates. Further investigation is required to address potential metering issues for facility ‘A’. This paper also explores the impact of key parameters—such as average temperature, VIIRS detection frequency, flow rate—on data accuracy and Nightfire (VNF) calibration to estimate flared gas voluems This study conducted an in-depth analysis of four facilities in collaboration with Petroleum Development Oman (PDO) and The World Bank through the Colorado School of Mines.