Variation of Total Stresses During Field Operation Using Finite Element Technique, Zubair Oil Field.

Abstract

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.