Evaluation model of nitrogen gas flooding in low permeability reservoir based on grey relation grade

Key words:  nitrogen gas flooding  grey relation grade  weight  evaluation model

Abstract:

Based on the nitrogen gas flooding mechanism, the influence factors on gas injection effect were analyzed. Several better-classification parameters were screened out, and the technical threshold value of each parameter was evaluated. Based on the grey relation grade theory，the objective weights of evaluation indexes were determined by grey relation grade of reservoir parameters. And a new multi-attribute model evaluating the potential of nitrogen gas flooding in low permeability reservoir was presented by taking the weighted grey relation degree of target reservoirs as the evaluation criteria. The applied results show that the model is practicable and effective, which can give right potential order among the candidate reservoirs for nitrogen gas flooding, improve the accuracy of reservoir evaluation, and thus reduce blindness of reservoir selection. This model can be used to guide reasonable development and risk assessment of nitrogen gas flooding in low permeability reservoir.