Abstract
The failure of the cement annulus seriously restricts the process of multi-stage horizontal fracturing, and it exacerbates the failure of casing. The plastic zone of the continuous cement can be determined by FEM with relative accuracy, while the damage process of cement from continuum to non-continuum can be simulated by DEM. Firstly, FEM was employed to simulate the stress distribution across cement, and the stress on each node at the boundary of the plastic area was recorded at each time point. Secondly the continuous elements in the plastic area were transformed into the discrete particles. A microscopic bond contact model for cement was proposed and integrated into a commercial discrete element code PFC2D. The node stress of the finite elements was equivalently applied on the boundary of the particles through the interpolation method, then the continuous loading and unloading process were applied on the particles area again. It is shown that the cement annulus integrity becomes deteriorated when the internal pressure exceeds the average in situ stress on wellbore cross-section. The cement annulus integrity shifted from rapid decline to smooth rise with the increase of the stiffness ratio between casing and cement annulus. The cement annulus was integrity rapidly weakened when the nonuniformity modulus increased, and the maximum number of multi-stage horizontal fracturing is correlated to the strength of cement annulus.
Access this chapter
Tax calculation will be finalised at checkout
Purchases are for personal use only
References
Fang, J., Yue, B., Zhao, H., et al.: Analysis of surface loading on casing and cement sheath under nonuniform geologic stress. J. Univ. Pet. China Ed. Natural Sci. 21(1):46–48 (1997)
Deng, J.: Simulation experiment on effects of cement mantle features on casing loading. J. Univ. Pet. China Ed. Natural Sci. 21(6), 24–28 (1997)
Zhang, G., Chen, M., et al.: Study on casing load in injections wells of shale formation and the critical injection time. J. Harbin Inst. Technol. 38(8), 1273–1277 (2006)
Yin, Y., Chen, Z., Li, P.: Theoretical solutions of stress distribution in casing-cement and stratum system. Chin. J. Theor. Appl. Mech. 38(6), 835–842 (2006)
Oñate, E., Rojek, J.: Combination of discrete element and finite element methods for dynamic analysis of geomechanics problems. Comput. Methods Appl. Mech. Eng. 193(27–29), 3087–3128 (2004)
Takada, S., Katagiri, S.: Development of FEM-DEM combined method for fracture analysis of a continuous media. Mem. Grad. Sch. Sci. Technol. Kobe Univ. 20(A): 65–79 (2002)
Feng, C., Li, S., Liu, X.: A procedure for transiting FEM into DEM and its application. Rock Soil Mech. 36(4), 1027–1034 (2015)
ABAQUS Analysis User’s Manual (version 6.14). ABAQUS, Inc. (2006)
Itasca Consulting Group. PFC2D Users, Manual (version 3.1). Minnesota: Inc. (2004)
Author information
Authors and Affiliations
Corresponding author
Editor information
Editors and Affiliations
Rights and permissions
Copyright information
© 2017 Springer Science+Business Media Singapore
About this paper
Cite this paper
Xing, Y.K., Zhang, G.Q., Li, S.Y., Zhang, Z.K., Pan, R. (2017). Investigation on the Integrity of Cement Annulus During Multi-stage Horizontal Fracturing with FEM/DEM. In: Li, X., Feng, Y., Mustoe, G. (eds) Proceedings of the 7th International Conference on Discrete Element Methods. DEM 2016. Springer Proceedings in Physics, vol 188. Springer, Singapore. https://doi.org/10.1007/978-981-10-1926-5_39
Download citation
DOI: https://doi.org/10.1007/978-981-10-1926-5_39
Published:
Publisher Name: Springer, Singapore
Print ISBN: 978-981-10-1925-8
Online ISBN: 978-981-10-1926-5
eBook Packages: Physics and AstronomyPhysics and Astronomy (R0)