Optimization of Iranian gas refineries with environmental ‎approach in ‎Data Envelopment Analysis ‎framework

First step for increase efficiency and productivity is measure, ‎analyze, plan, and improve this applied part that the ‎most important step can have measuring be the performance ‎and optimization in the firms development path. This research uses the DEA and Malmquist index to evaluate the total TFP productivity utilization for all natural gas refineries during the years 2009-2015 and using an input-oriented approach with two Input and output are two outputs. The results of the evaluation indicate the technical-environmental efficiencies of the Khangiran (Hasheminejad) and Parsian refineries among the 12 natural gas refineries during the years under study. By calculating Malmquist‎ total productivity index among natural gas refineries, on average, six positive growth refineries and six other refineries have been extracted from negative growth in productivity over the years considered