Dynamic analysis of a cylindrical casing-cement structure in a poroelastic stratum

作者:Xia, Yang; Jin, Yan*; Chen, Mian; Lu, Yunhu
来源:International Journal for Numerical and Analytical Methods in Geomechanics, 2017, 41(12): 1362-1389.
DOI:10.1002/nag.2680

摘要

The transient response of a cylindrical casing-cement structure in a poroelastic stratum under dynamic radial tractions is one of the significant issues during the analysis of downhole operations and the selection of safe material. Based on the Biot theory and general elastic mechanics, this paper gives a set of exact solutions for radial displacement, stresses for the casing-cement system and the pore pressure of the infinite surrounding poroelastic stratum in the Laplace transform space. Solutions are presented for three different types of transient radial loadings acting on the surface of casing, i.e., suddenly applied constant load, gradually applied step load and triangular pulse load. Time domain solutions are obtained using a reliable numerical method of inverse Laplace transforms. A detailed parametric study about the transient response is presented both at the casing-cement interface and the cement-stratum interface, and the distributions of the pore pressure and the effective stresses in the stratum are also examined.