[01] Hussein Saeed Almalikee, Fields Division, Basrah Oil Company, Basrah, Iraq. [02] Fahad Mansour Alnajm, Geology Department, University of Basrah, Basrah, Iraq.

Minimum and maximum horizontal stress (S_hmin and S_hmax) are two of the three principal stresses that are required for any Geomechanical study, especially wellbore stability analysis, sand production and hydraulic fracturing. The values of horizontal stresses are also important and required for planning high angle and horizontal wells, especially in Rumaila super-giant oil field in order to target thin sandstone layers in the non-depleted units of the Zubair reservoir to increase production with less numbers of new oil wells. S_hmax and S_hmin can be directly measured using leak off test (LOT), extended leak off test (XLOT), or indirectly estimated by well log data. In this study, S_hmin and S_hmax were predicted using Eaton method, this method relies on the relationship between overburden stress, pore pressure and rock mechanical properties (Poisson’s ratio), these parameters could be estimated by employing logging data such as sonic and density logs from five wells in Rumaila oil field. The values of S_hmin was then calibrated with extended leak off test measurements in order to add the effect of tectonic, results showed that Rumaila oil field is under strike slip stress regime (S_Hmax>S_V>S_hmin) and the optimal direction to drill deviated and horizontal well is parallel to the maximum horizontal stress direction.

Horizontal Stress, Wellbore Stability, Poisson’s Ratio

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