A Study on Calculation Model of Stress Field Around Wells Considering Rock Elastic-plastic Deformation

doi:10.11885/j.issn.1674-5086.2019.06.14.01

Abstract

Abstract: Aiming at the elastic-plastic characteristics of coal, shale and other rocks, a calculation method for stress field of elastic-plastic formation is established, which divide the formation into the plastic softening, the plastic hardening and the elastic zone along the radial direction. In this new model the nonlinear hardening and softening deformation of rock and the percolation effect of the working fluid are considered. The analysis shows that the plastic zone range is positively correlated with the borehole fluid pressure, Poisson's ratio and the initial pore fluid pressure, and is inversely related to the strength of the rock. Compared with the elastic state, the plastic deformation of rock decreases the stress concentration effect, and the plastic deformation of the rock has a little influence on the radial stress of the formation while it can increase the circumferential stress of the formation.

Key words: coal, shale, elastic-plastic, nonlinear constitutive equation, stress field around wellbore

CLC Number:

TE21

LI Xiaogang, LI Yunyun, HU Qiuping, ZHANG Xiang, YI Liangping. A Study on Calculation Model of Stress Field Around Wells Considering Rock Elastic-plastic Deformation[J]. 西南石油大学学报(自然科学版), 2020, 42(5): 135-144.

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