The Key Factor Analysis to the Reservoirs on the Basis of Bayesian Law

Abstract

The oil price shocks further exaggerates the inherent difficulties in studying exploration of complex reservoirs. Therefore, as the main way of reducing cost, it's necessary to analyze the main factors of complex reservoir formation before intensively exploration. Bayesian law is used to build a diagnostic model. Six key factors in the effectiveness of hydrocarbon reservoir are starting points. According to the maximum entropy principle and single well event’s probability of drilled wells with prior probability, the probability of adverse factors in the forming of hydrocarbon reservoir can be concluded. Therefore, influencing degree of each factor can be obtained. Meanwhile, by the theory of Slicher, the distribution of oil and gas reservoirs conform to Poisson’s distribution. The results can be applied to calculate the probability of hydrocarbon reservoir’s discovery and to predict the exploration potential of survey region. From the perspective of testing, this paper use Wushi sag as an example. By using the single well event’s probability of nine drilled wells and calculating the influence value of key factors which are adverse to form the hydrocarbon reservoir in Wushi sag, this paper focuses on the key aspects-poor reservoir condition and absent migration pathway. By applying Poisson’s distribution to study the exploration prospect, this study reveals that there is at least one district where commercial gas reservoirs will be discovered in Wushi sag. In conclusion, the diagnostic model based on Bayesian law provides a new and unique way of thinking to solve the geological problems in complex condition, and it is effective to the petroleum geological knowledge.