Analysis of stress regime in Shah Deniz oilfields and wellbore stability, in south Caspian Sea basin

Wellbore instability is one of the main problems during drilling of oil and gas wells. Analyzing and wellbore instability prediction is important. In-situ stress measurement and stress regime are important for stability studies. This study was carried out in one of the oilfields in the south Caspian basin in Iran. The compressional stress regime in the studied field was determined based on regional stress indicators and larg scale tectonic observations. . This study presented the effect of borehole inclination and azimuth on borehole stability under reverse fault regimes. The magnitude of stresses was determined from measured sonic velocities, density log and predicted pore pressure utilizing the Eaton method. In this study, the modified Lade model have been utilized to perform stability calculation for different inclinations and azimuths. In this study, to perform stability calculation with the use of STABview software is presented. It is shown that drilling wells parallel to maximum in-situ horizontal stress (NE-SW) causes less stability problems. The results of this study could help in the mitigation and/ or prevention of wellbore stability issues in this oilfield.