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In engineering, some requirements must be met to ensure the safety and economy of the projects. Regarding oil exploration, there is a concern about the risk of oil well failure, considering the new challenges of this sector, especially in offshore exploration. In order to improve the decision-making process in structural safety analysis, the structural reliability methods arise with the possibility of calculating the probability of failure of the structure, taking into account the inherent uncertainties of the design variables. However, in order to assure the success of the reliability analysis, it is necessary to have the statistical description of the design variables and a mathematical model to determine the failure functions of interest. In the context of oil well design, the API 5C3 recommends the use of data with independent random variables (rv) in the reliability analysis of well casing tubes, because this consideration simplifies the problem and is beneficial for safety. However, the present work aims to analyze the influence of the use of correlation between the rv in the results obtained through structural reliability methods. Therefore, the model developed by Klever and Tamano is used as Ultimate Limit State (ULS) equation, as determined by API 5C3, where correlations range from negative to positive values in the reliability analysis. Finally, the results obtained are discussed, in order to evaluate the importance of the use of correlation between rv on the casing integrity analysis.