Numerical simulation analysis of the influence of ovality on the strength and stability of the empty pipe section of the double-plug buoyancy method
GUAN Zhao
CHENG Hua
YANG Yang
XU Lei
LI Hua
WANG Xuesong
SONG Chunfang
Abstract：When the double-plug buoyancy method is used to lower the large-diameter casing in coal mine gas extraction well,if the casing ellipse is too large,it is easy to deflate the pipe under the action of external mud pressure,resulting in huge economic losses.Therefore,in this study,the pipe pa-rameters under the double plug buoyancy method are calculated first,and the dangerous cross section of the casing is analyzed.Then a finite element model is established to analyze the stress state and de-formation of casing with ellipticity by static method.Finally,by using eigenvalue buckling analysis and nonlinear buckling analysis,the collapse strength of large diameter casing with different ellipticity is calculated.The results show that when the casing ellipticity increases from 0％to 1％,the elastic collapse strength decreases by 26.8％,and the casing with ellipticity less than 1％meets the require-ments of elastic strength and stability when the safety factor is 1.5.The research results are expected to provide some reference for the design of casing parameters for gas drainage holes.
Keywords：gas extraction welldouble-plug buoyancy methodlarge diameter casingovalitybuckling analysis
Publication Date：2025-06-15
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：7( 43-49 )