Abstract: There are a lot of pollutant sources in oil and natural gas industry. They should be tackled in a comprehensive way in no time. The comprehensive evaluation of polluted extent, polluted range and damaged extent can provide scientific foundation for pollutants control. However, an evaluated method of fuzzy matter-element is presented because the concepts of polluted extent, polluted range and damaged extent themselves are fuzzy.
The basic thinking of this method is to combine fuzzy analysis with matterelement analysis, build up several kinds of composite matter element according to the three main factors-polluted extent, polluted range and damaged extent and corresponding secondary ones and their weights, and then take mean and maximum and minimum of the value of fuzzy parameter corresponding to the weights of the main factors of environment pollution as evaluation indexes at the same time and make evaluated composite fuzzy matter-element. Take an accident of environment pollution occurred in the suburbia canal in certain county as an example, results have shown effectiveness of the method.

Key words: fuzzy mathematics, matter-element analysis, pollution, comprehensive evaluation