下部钻柱有限元动力学仿真研究

FINITE ELEMENT DYNAMICS emulation OF BHA

针对下部钻柱在钻井过程中的振动状态,分析了振动机理,并建立下部钻柱组合节点单元三维动力学模型,运用强迫频率理论和高斯列主消元法对动力学方程组进行求解,得到不同转速下的最大径向变形及弯曲应力,绘出相应的幅频响应曲线,确定相应的临界转速。研究表明,钻柱转速对钻柱振动影响较大,通常钻柱工作转速要避开钻具组合谐振频率,可减缓钻柱振动,保护钻柱。

The mechanism of BHA vibration in the process of drilling is analyzed,then a three-dimensional finite element mechanical model of BHA is established,by using Forced Frequency Theory and Gauss algorithm for solution of dynamics equations,maximum radial deformation and bending stress at different rotation speed are obtained,and the corresponding frequency response curves drawn to determine the critical speed.Research showed that drillstring rotational speed greatly impact drilling string virbration,Drillstring usually working rotational speed should avoid the BHA speed resonant frequency that can slow down the drillstring vibration for protect drillsting.