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摒弃常规方法中管柱屈曲挠曲线的假设,建立垂直井筒内悬挂管柱的几何和接触双重非线性力学模型,虚拟较大的阻尼比,进行有限元计算。采用正向加载法得到管柱稳定的连续接触的螺旋屈曲构型;采用逆向加载法,根据螺旋屈曲构型,逐渐增加悬挂拉力,进行屈曲演变分析;并分析摩擦力和管柱长度对临界载荷的影响。结果表明:螺旋屈曲向正弦屈曲转变是突变的过程,屈曲模态构型包括螺旋屈曲构型、刚螺旋屈曲和正弦屈曲。摩擦力对临界载荷的影响甚微。随着管柱长度增加,各阶屈曲模态的临界载荷均逐渐减小并趋于常值。此方法适用于斜井、曲率井和水平井管柱的屈曲过程分析。 相似文献
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This paper presents a nonlinear finite element method to resolve the problem of the nonlinear contact between the drillstring and hole by using a Multi-directional Contract Gap Element(MCGE) contacting at approprizte positions in each beam element.The method was successfully applied to the Daqing Oil Field GP1 well.It was shown that the drillstring‘s contact resistance at any well depth could be obtained by calculations and that as the enor in the calculation of the hole top load is below 10%,the calculation result can provide theoretical basis for the design and operation of drillstrings. 相似文献
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