Solid expandable tubular (SET) is one of the most fundamental solutions to solve the challenges facing the industry. The concept of the SET is to expand the diameter of the tubular to the required size with a mandrel. The benefit of this technology is cost-effective way, and provides solution to many problems. Many researches had been published in the same topic and they focus on the effect of different mechanical parameters on the expansion process. The present research aims to simulate the theoretical approach of the straight mandrel with different parameters for different materials. The objective of different parameters is to test the validity of the equations. Two types of mandrel shape that are used, the first one is with straight mandrel and the second type is the curved mandrel. The solution will check the effect of the expansion ratio, friction coefficients and mandrel angles on the axial stress, expansion force and the dissipated energy. This study will compare as well both shapes of the mandrels. The second part of the thesis is to simulate the SET system in finite element software which is ABAQUS. The objective of this simulation is to verify the theoretical solutions. MATLAB is used to solve the simplified analytical solutions and then compare it to FEM outputs. Also the research introduces two special cases to study the process, the first one is using Aluminum as an alternative metal and the second case introduce pits corroded in the expansion tube. In addition to that different geometries that used in real industry are simulated in ABAQUS and solved numerically as well. Different boundary conditions are introduced in this study, fixed bottom-fixed top and free bottom-fixed top tubes, in order to their behaviors and how will affect the expansion process. This solution can be used to predicate the behavior of the expansion process as it is verified in ABAQUS. The axial stress for both mandrels increase as the friction coefficients increase. The same behavior can be concluded for the expansion ratio, which causes the axial stress to rise as it is increased. However the axial stress decreases as the mandrel angle increases in the straight mandrel, this relationship is not applied in the curved mandrel as the angle changes during the expansion process.