Numerical Simulation of Borehole Stability in Underbalanced Drilling Coal Seam

doi:10.16182/j.issn1004731x.joss.201811025

Abstract

Abstract: According to the formation parameters of No.3 coal seam in the Qinshui Basin, Shanxi Province, considering the interaction between seepage and deformation in the borehole wall of coal seam, using the finite element method for establishing the stable elastoplastic numerical model of the borehole in coal seam,the variation of pore pressure near the wellbore wall with the seepage time and the effect of time delay on wellbore stability under underbalanced drilling condition were studied. The variation law of maximum displacement and maximum plastic deformation around borehole wall with bottom pressure were analyzed. The simulation results show that there is indeed a time delay effect on wellbore stability and the plastic analysis of coal and rock under consideration of seepage and deformation coupling conditions is more reasonable and effective, and it provides sufficient time conditions for guiding drilling construction.

Key words: coalbed methane, borehole wall stability, wall seepage, pore pressure, time delay

CLC Number:

TE31

Li Yumei, Su Zhong, Zhang Tao, Zhang Delong, Yu Liwei, Si Na. Numerical Simulation of Borehole Stability in Underbalanced Drilling Coal Seam[J]. Journal of System Simulation, 2018, 30(11): 4249-4255.

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