Master of Science in Petroleum Engineering (MSPE)
Wellbore stability analysis acts an important role in the drilling design to avoid pipe-stuck, lost circulation and the other instability-induced problems. However, the conventional linear elastic model used by the industry is too conservative in predicting the mud weight window. This project is aimed at improving the accuracy of wellbore stability analysis. An elastoplastic model with Drucker-Prager yield criterion featured by strain hardening is proposed to characterize the rock behavior. Object-oriented finite element analysis simulator, NSMOOM, is programmed in MATLAB. The simulator is verified with the analytical solution in the elastic domain and with the commercial software ABAQUS in the elastoplastic domain. Upon the good verification results, the code is applied to an under-balanced-drilling case. For the case study, a good match is shown between the prediction of the proposed elastoplastic model and the actual wellbore response. On the other hand, no available mud weight window for under-balanced-drilling can be calculated by the pure elastic model. In conclusion, the proposed model provides a more realistic tool to predict wellbore stability.
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Huang, Chang, "A Numerical Investigation of Wellbore Stability Problems Using an Elastoplastic Model" (2016). LSU Master's Theses. 2432.