The One important rock mechanical property in geomechanical investigations is internal friction angle. In order to predict wellbore failure and construct a geomechanical earth model, friction angle is essential. It is usual to estimate the internal friction angle using core tests, but this approach requires more cores and is expensive. Instead, several empirical correlations were found to estimate the internal friction angle from logs data. The goal of this study was to determine the most accurate approach for estimating internal friction angle from log data and to demonstrate how clay volume and porosity influenced this estimate.This property is estimated using three different correlations built within Techlog 2015 software depend on neutron, density, and gamma ray logs data. The findings demonstrate that Weingarten and Perkins Weal correlation is used, especially when water production is actually occurring. The gamma ray technique does not accurately match the core data since it only employs the gamma ray log. With effective porosity and clay volume used as input data for the Plumb Clay Volume and Porosity correlation, the findings demonstrate an excellent match with the core data. The frictional angle exhibits minimal values in the Tanuma formation and at various depths as a result of a decrease in effective porosity and an increase in shale volume. The results showed that for determining frictional angle, the Plumb correlation approach was the most accurate.

The Zubair oil field is predominantly plagued by geomechanical issues, which can result in significant non-productive time. The aim of this study is to present a reservoir model and a geomechanical model utilizing the finite element method. The intriguing data consisting of logs, calibration data, drilling reports, and mud reports were utilized to construct one-dimensional models (1D) for each well using Techlog 2015 software. Furthermore, the 3D geomechanical model was built utilizing Petrel 2017 software, while the finite element technique was implemented using the CMG 2018 program to predict the total stress states during production or injection operations in the field over a span of 10 years.The analysis results of all mechanical rock properties in the 3D geomechanical model revealed that Shuaiba and Al-Hammar domes were insufficient for maintaining stable wells, particularly in the Tanuma formation. However, the Mishrif formation displayed higher stability despite production. Furthermore, the 3D finite element model exhibited that the total horizontal stress decreased during production and increased in injection wells. This variation would result in an increase in the effective horizontal stress during production and a decrease in injection wells. Moreover, the effective vertical stress increased during production and decreased during injection wells. Based on these outcomes, it can be concluded that production could trigger an increase in the differential stress leading to rock shear failure, whereas in injection cases, pore pressure increased, and this caused tensile failure.