偏摩耗油井管のバースト強度のFEM解析と計算式

概要

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In a horizontal well or an extended reach well, which is promising for future well construction, a well casing is subjected to local weae of wall thickness on its inside surface due to rotational contact with a tool joint or drill pipe during drilling. Burst strength of worn casing is analyzed as an unstable problem by the elastic-plastic finite-element method (FEM) and the decrease ratio of burst strength due to casing wear is formulated by nonlinear programming using parameters of the wear shape. The elastic-plastic FEM is highly applicable, since values calculated by the FEM program agree well with those of experiments. It was found that the decrease ratio of burst strength of a worn casing is linearly proportional to the decrease ratio of wall thickness, and that the apical angle of the wear shape has little influence on burst strength.
1996-01-25