For the lower section of 8th member of the Shihezi Formation (Middle Permain) in the Su X block of the Sulige gasfield

significant degree of uncertainty was involved in early-stage evaluation of low-permeability gas reservoir due to immature understanding and incomplete information

which causes difficulty to a fine reservoir description.It is vital for a better reservoir evaluation to fully account for uncertainty and effectively magnify the differences of different reservoirs in evaluation results.In this paper

based on the idea of multi-information superposition

the methods of fuzzy mathematical evaluation and grey correlation analysis are linked by membership degree and are integrated to establish a more effective fuzzy-grey comprehensive evaluation model

along with differentiated and improved internal algorithm.The application of the model to reservoir evaluation in this study suggests that this method enhances the differences and precision for the low-permeability reservoir classification and characterization

with consideration of the fuzzy and grey properties of reservoir.In this case study

four types of reservoir are classified and the type Ⅰ and Ⅱ are deemed to be the favorable targets.The different reservoir categories are better separated in plane view than before.The comparison of evaluation results with the real production data and geological principles of fluvial deposition also displays good coincidence.This method may be effective and efficient for guiding the exploration and development of the gas field

and provide a new thought for similar low-permeability reservoir evaluation as well.