The Effect of Anisotropy of Medium on the Stress State around a Borehole

Abstract:

Based on the analytical solution for the stress field around an inclined borehole in an anisotropic medium, a computer program was developed and a serial parametric study was conducted. The effects of parameters such as degree of anisotropy, borehole inclination, bedding plane inclination and in-situ stress conditions on the stress distribution around a borehole were evaluated. The results showed that medium anisotropy has little effect on borehole fracture analysis at low borehole inclinations, but its influence becomes significant for highly inclined boreholes. As the degree of anisotropy varies the maximum shear stress changes remarkably. This indicates that the degree of anisotropy plays a role in the collapse failure of a borehole. The information generated in these studies can be used in predicting the fracture or collapse-initiating pressures.

• Periodical: Advanced Materials Research (Volumes 291-294)
• Pages: 2139-2144
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.291-294.2139
• Online since: July 2011
• Authors: Yong Shu Jiao, Mu Hui Fan, Li Juan Li, Zong Xi Cai
• Keywords: Anisotropy of Medium, Borehole, Parametric Study, Stress State

References

[1] G. Li, Y. F. Meng, H. B. Liu, Y. L. Zhou, Y. X. Zhu. Borehole stability challenges in gas drilling: Case studies in west Sichuan basin. International Oil and Gas Conference and Exhibition in Beijing, China 2010, pp.1229-1248

DOI: 10.2118/131034-ms

[2] S. Li, C. Purdy. Maximum horizontal stress and wellbore stability while drilling: Modeling and case study. Latin American and Caribbean Petroleum Engineering Conference in Lima, Peru 2010,. Vol. 4(1990), pp.1380-1390

DOI: 10.2118/139280-ms

[3] E. Karstad, B. S. Aadnoy. Optimization of borehole stability using 3D stress optimization. SPE annual technical conference and exhibition in Dallas, Texas, U. S. A (2005). pp.1-7

[4] S. Saeed, H. Geir, N. Runar. Numerical simulations of wellbore stability in under balanced drilling wells. Journal of Petroleum Science and Engineering Vol. 72(2010)3-4, pp.229-235

DOI: 10.1016/j.petrol.2010.03.022

[5] D. Gupta and M. Zaman. Stability of boreholes in a geologic medium including the effects of anisotropy. Applied Mathematics and Mechanics (English Edition), Vol. 20(1999)8, pp.837-866

DOI: 10.1007/bf02452483

[6] J. Cui, Y. S. Jiao, W. Y. Cao and Z. X. Cai. A study on the stress field around a borehole in anisotropic formation. Engineering Mechanics (in Chinese), (2011 accepted).