During pre-project planning as an essential phase of a project, fundamental decisions that lead to project success or failure will make. This phase of a project is more important essentially in oil, gas and petrochemical mega projects that tremendous amount of resources should consume. Uncertainty in the initial phases of the project is at the highest level and therefore major project decisions should be made based on the minimum level of information and assurance of future. In this paper, a

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... formance forecasting model for oil industry projects proposed that based on Neuro-fuzzy inference systems and rooted in project progress functions which known as S curve models. In this study types of functions and models that can generate project S curves are investigated and nine most used functions identified. In the next step six performance variables in two main sections include project progress and resource growth recognized and 25 variables in two categories and four clusters using close questionnaire approach identified. Finally a model for project performance prediction based on Adaptive Neuro-Fuzzy Inference System developed.