Drastic growth in greenhouse gas (GHG) emissions in the last few decades, due mainly to the development of industrial activities, is one of the most important parameters that greatly influence global warming and climate change. While oil and gas industry contribute significantly to global GHG emissions because of their rate of flaring, it is practically impossible to measure and monitor the composition and amount of the gas streams sent to a flare and their combustion products. In the present study, a model is proposed to estimate the flow rate and composition needed for calculation of GHG emission from the flare network of a natural gas processing plant in Asalouyeh, southern Iran, based on the sources of flared gas. This model also makes it possible to determine the source of each flared gas mixture and the reliability and availability of the processing units. The comparison between cumulative flow rates of flared gas from the model and field measurement shows an agreement with the correlation coefficient of more than 0.98. The accuracy of the model in the prediction of the flared gas composition was validated against actual compositions using gas chromatography. The error of less than 8% between actual results measured by gas chromatography and the results predicted by the proposed model for main components such as methane and carbon dioxide shows the acceptable accuracy of the proposed model. The model not only makes online monitoring of the flare network possible but also facilitates decision making about flare gas reduction. (C) 2019 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.