顶驱钻井柔性钻柱动力学特性分析

Dynamic Analysis of Flexible Drilling Characteristics for Top Drive

与单独分析钻杆纵向振动不同,将钻柱、吊环、顶驱装置、水龙头、起升系统和井架组成的柔性多体系统与钻井液、井壁耦合进行分析。首先推导了多体系统在耦合条件下起下钻过程钻柱系统纵振方程和频率方程,把内外钻井液对钻柱系统的作用力折算成等效的附加质量,运用Matlab编程计算,得到钻柱前8阶固有频率的理论解,并与采用Ansys软件计算得到的数值解比较,验证了理论推导的合理性;其次,针对钻柱提升或下放速度与加速或减速所延续的时间的比值与动载的线性关系,对钻柱系统进行谐响应分析,得出了不同v/t值下钻柱系统的动力响应。为起下钻过程中合理的起升、下放速度和时间参数设计提供了参考依据。

Unlike the past single longitudinal vibration analysis of drill string,this paper analyzed the flexible multibody system consists of drill string,elevator link,TDS,hoisting system and derrick,along with the coupling of drill string and drilling mud.On the condition of coupling,vibration and frequency equation of multibody system were deduced on round trip.Moreover,the effect of mud inside and outside to drill string was converted to equivalent added mass.Exact solutions of the first eight natural frequencies acquired by using matlab software were compared with the numerical solution through ansys software,which verified the rationality of theoretical analysis.In addition,according to the linear relationship between the dynamic load and velocity/time ratio,harmonic response analysis of drill string was performed;therefore,dynamic responses under different velocity and time ratios were obtained.This work provided reference for reasonable parameter designing of velocity /time ratio on round trip operation.