Numerical Investigation of the Impact of Geomechanical Parameters of Formations on Well Integrity of One of the Iranian Oil Fields

Document Type : Research Paper


Faculty of Mining, Petroleum and Geophysics Engineering, Shahrood University of Technology, Shahrood, Iran


Well integrity is defined as the application of technical and operational solutions to reduce the uncontrollable risk of fluids leakage in the well lifetime. In any drilling and production operation, lack of knowledge about geomechanical behavior of the surrounding formations is considered as a major risk. Therefore, in-situ stress conditions and mechanical properties of formations are important factors in well integrity studies. In this paper, a 3D finite element model was built to simulate the integrity of wells. An FEM analysis was used to investigate the plastic deformation in cement and theVon Mises failure criterion inside the casings under different stress conditions, and to study the mechanical properties of the formation. A clear increase in plastic strain in the cement and Von Mises stress inside the casings was observed with increasing the ratio of horizontal to vertical stress in orthotropic and isotropic conditions as well as with increasing the difference between horizontal stresses in anisotropic conditions. When conducting the translation error sensitivity analysis, the impact of major mechanical parameters of the formation was evaluated as well. The results showed thatby increasing Young's modulus, cement became hard and brittle. Meanwhile, an increase in the Poisson ratio led to plastic behavior.The maximum plastic strain was found at the cement-casing boundary due to the presence of a lower cement-formation friction value. The highest Von Mises stress value in the casings was also produced parallel toward the minimum horizontal stress.Additionally, with an increase in the cohesion and friction angleof formation, the cement became harder, and consequently, the safety factor for the casings increased.


[1] N. Standard. (2004). Well integrity in drilling and well operations, D-010, rev, vol. 3.
[2] D. U. Etetim. (2013). Well Integrity behind casing during well operation. Alternative sealing materials to cement, Institutt for petroleumsteknologi og anvendt geofysikk.
[3] Sangesland, S., Rausand, M., Torbergsen, H., Haga, H., Aadnøy, B., Sæby, J., Johnsen, S., Lundeteigen, M. (2012). An Introduction to well integrity, Rev 0.
[4] N. C. Himmelberg. (2014). Numerical simulations for wellbore stability and integrity for drilling and completions. Missouri University of Science and Technology.
[5] M. Shahri, J. J. Schubert, and M. Amani. (2005) Detecting and modeling cement failure in high-pressure/high-temperature (HP/HT) wells, using finite element method (FEM), in International Petroleum Technology Conference.
[6] C. Topini, F. Bertolo, G. Capasso, and S. Mantica. (2011). Buckling analysis for the long-term integrity evaluation of a hydrocarbon well, in Proc. Simulia Customer Conference, Barcelona, Spain.
[7] Li, Y., Yuan, J., Qi, F., Liu, S., Wang, Z., & Qu, C. (2012, January). Analysis of cemented casing mechanical failure under arbitrary in-situ stress field coupling effects of downhole pressure and temperature. In IADC/SPE Asia Pacific Drilling Technology Conference and Exhibition. Society of Petroleum Engineers.
[8] Feng, Y., Podnos, E., & Gray, K. E. (2016, June). Well integrity analysis: 3D numerical modeling of cement interface debonding. In 50th US Rock Mechanics/Geomechanics Symposium. American Rock Mechanics Association.
[9] Z. Shen and F. E. Beck. (2012). Three-dimensional modeling of casing and cement sheath behavior in layered, nonhomogeneous formations, in IADC/SPE Asia Pacific Drilling Technology Conference and Exhibition.
[10] M. G. Haider, J. Sanjayan, and P. G. Ranjith. (2012). Modeling of a well-bore composite cylinder system for cement sheath stress analysis in geological sequestration of CO2, in 46th US Rock Mechanics/Geomechanics Symposium.
[11] S. Abaqus. (2017). Abaqus Version 2017 Analysis User’s Guide. [12] National Iranian South Oil Company, geological report, 2009. [13] G. Capasso and G. Musso. (2010). Evaluation of Stress and Strain Induced by the Rock Compaction on a Hydrocarbon Well Completion Using Contact Interfaces with Abaqus,” in Proc. ABAQUS Users’ Conference, Providence RI, USA.
[14] H. Arias. (2013). Use of finite-element analysis to improve well cementing in HTHP conditions. Texas A&M University.
[15] J. Fan and B. Yue. (1997). Analysis of surface loading on casing and cement sheath under nonuniform geologic stress, JOURNAL-UNIVERSITY Pet. CHINA Nat. Sci. Ed., vol. 21, pp. 46–48.
[16] F. Jun, Z. Huaiwen, Y. Boqian, and S. Yufeng. (1995). Analysis of Loading Propekty of Casing and Cement Sheath Under Nonuniform Geologic Stress [J], J. Univ. Pet. China, vol. 6.
[17] L. Jun, C. Mian, L. Gonghui, and Z. Hui. (2005). Elastic-plastic analysis of casing-concrete sheath-rock combination, Acta Pet. Sin., vol. 26, no. 6, pp. 99–103.
[18] J. Li, M. Chen, H. Zhang, and S.-L. Zi. (2005). Effects of cement sheath elastic modulus on casing external collapse load, Shiyou Daxue Xueban Ziran Kexue Ban(Journal Univ. Pet. China Nat. Sci. Ed., vol. 29, no. 6, pp. 41–44.