Determination of Direction and Magnitude of in Situ Stresses by Borehole Breakout Method in an Oil well in the Southwest of Iran

Determination of in situ stress-direction and magnitude are prerequisite for any oil well drilling and oil field development such as hydraulic fracturing. One of the simplest and most widely used methods is called borehole breakout analysis. Breakouts are compression fractures made in the direction of minimum horizontal in situ stress (Sh), if drilling mud pressure be lower than optimum mud pressure. Some borehole imaging logs such as FMI, FMS and UBI are appropriate tools for wellbore fracture detection. These fractures are distinguished in the logs as dark and symmetrical points (or lines) on both sides of the well and are used as an indicator for in situ stress studies. The size and shape of these fractures are strongly depend on the magnitude of the in situ stress. Therefore, many researchers suggested that by analyzing the geometric shape of the borehole breakout is an appropriate technique for estimation of in situ stress components.