| Abstract |
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The most important challenge in oil engineering is to reach the oil layer without drilling problem. Despite the drilling problems, a very good strategy with regard to geomechanical modeling is required to achieve the optimum mud pressure for safe drilling with respect to the pore pressure. The lack of accurate prediction of pore pressure and wellbore stability analysis results in problems such as well blowing, wellbore wall fractures, and so on. Wellbore wall instability increases the duration of drilling operation, increases costs and sometimes leads to the abandonment of the well before reaching the target point. During drilling, because of the relationship between the mud pressure and the main stresses, a field called induced stress is created that calculating the stresses it is very important to determine the types of wellbore wall fractures. Accordingly using geomechanical analysis and the values of horizontal stress and pore pressure, the optimal mud pressure was obtained. In this study, geomechanical modeling was performed and using single-axial compressive strength, it was determined that the soft formation material is clay and sand. The fault regime in the formation was defined as strike-slip fault. Finally, using the drilling mud window, the minimum mud pressure level of 60-80 MPa and the maximum drilling mud pressure that the formation can tolerate was introduced as 95-115 MPa. Then, after applying the drilling mud pressure with which the well was drilled, and FLAC software it was revealed that in the over-balanced drilling, no falling occurs in the well, however, some levels of collapse is predicted on the walls in the balanced drilling. |
