钻柱和地面管道对随钻测量技术连续波信号的滤波特性分析

Analysis of Influences of Drill Stem and Pipelines above Ground on MWD Continuous Waves' Filtering Signals Characters

在随钻测量(MWD)过程中,目前还没有描述MWD信号传递和衰减的较好方法。提出以水击方程为基础,推导平均摩擦力情况下连续波动信号在大倾角钻柱中的传递方程组,给出了方程组的解;借鉴电力线路信号传递的矩阵分析方法,建立钻柱内信号的传递矩阵,并利用传递矩阵分析井下不同频率的正弦波动信号在钻柱中的传递衰减和分布情况,从理论上说明了在连续波MWD过程中钻柱对于信号的传递类似于低通滤波器的原因。利用矩阵传递模型分析推导了带分支管的地面管道的信号传递矩阵,根据地面分支管对信号传递的影响,设计用于滤除MWD信号中特定频率信号的管道结构,绘制钻井液管道的频率幅值特性图,可以用于滤除特定的干扰信号,为MWD通信频率的选择和地面管道布设提供理论基础和应用指导。

Considering the fact that lack of efficient methods to describe MWD(measurement while drilling) signals’transit and damping in the operation,having water hammer equation based to deduce continuous waves’transfer equation in a drill stem with high inclination-angle under the condition of average frictional force and to present the solution of this equation;having the matrix analysis method for signal transmission in the power line referenced,the transfer matrix of the signals in a drill stem was established to analyze both transfer attenuation and distribution of the sine fluctuation signals at different frequencies in a drill stem,which theoretically illustrates the causes of the resemblance of the signals between an low-pass filter and the continu-ous waves of MWD in a drill stem.Through making use of the model of matrix transfer,the signal transfer ma-trix of the pipeline with branches above the ground was deduced;and basing on the influence of the branches on signal transferring,the special pipeline structure in which the MWD signals of particular frequencies can be eliminated was designed,including the characteristic map of the frequency and amplitude in the pipelines of drilling fluid which can be used to eliminate the disturbance signals.This can provide the theoretical founda-tion and application guidelines for choosing the transfer frequency of MWD and installing the pipes above the ground.