An Empirical Correlations to Predict Shear Wave Velocity at Southern Iraq Oilfield

Abstract

Geomechanical studies are very important in the development stages of oil fields to solve many problems such as wellbore instability and sand production. However, this study is not complete without the availability of mechanical properties of rocks. These properties estimate from petrophysical logs based on the compressional and shear wave velocities. But the shear wave is often missing from most wells, and the reason might be cost-saving. Therefore, this study aims to find correlations to predict the shear wave velocity of the Mishrif reservoir.
 The empirical equations are formed using log data of six wells drilled in the southern Iraq oilfield. The Statistical Package for the Social Sciences (SPSS) software was relied on to find the empirical correlations. Eleven empirical equations have been obtained, but the best are three equations: linear, quadratic, and cubic because they give the highest value of R2 = 0.924. Also, these three equations (linear, quadratic, and cubic) have been tested for sensitivity, and the most stable equation was quadratic. Moreover, the equations examined using four wells measured shear wave velocity, and the results were very reliable. Finally, the equations were tested by estimate the shear wave in wells where there are no measured data, then calculating the mechanical rock properties, predicting wellbore instability, and comparing the breakout with the caliper, and the result was excellent. This study is an excellent solution for shear wave estimation in wells where there are no measurements