随钻声波测井中消除钻铤直达波方法的研究与验证

随钻声波测井是准确获取地层信息的重要手段,但是其中沿着钻铤传播的直达波严重干扰地层波的测量。为了消除钻铤直达波对测井数据的影响,提出了一种利用单声源延迟反相激励消除钻铤直达波的新方法。该方法通过自适应滤波有源噪声控制技术虚拟出一个发射声源,实现单声源和虚拟声源激发的两列钻铤直达波到达相同接收器时同频反相相互消除的目的,从源头上消除钻铤直达波对地层波信号的影响,避免了因对钻铤进行物理加工,导致降低钻铤机械强度所引发的测井风险。通过对单声源延迟反相激励原理模型的分析、对原理模型的仿真计算和开发基于自适应滤波有源噪声控制技术的软件对实际测井数据的处理,均验证了该新方法对随钻声波测井中的钻铤直达波消除效果明显。

Research on Eliminating Drill Collar Direct Wave in LWD

Acoustic logging while drilling (LWD) is an important method to obtain formation information accurately, but the direct wave propagating along drill collar seriously interferes with the measurement of formation wave. In order to eliminate the influence of drill collar direct wave on logging data, a new method of eliminating drill collar direct wave by using single sound source opposite phase excitation is proposed. According to the method, an emission sound source is simulated through an adaptive filtering active noise control technology, so that the aim of mutual elimination of the same frequency and opposite phases when two drill collar direct waves excited by a single sound source and a virtual sound source reach the same receiver is realized, the influence of the drill collar direct wave on formation wave signals is eliminated from the source, and the logging risk caused by reducing the mechanical strength of the drill collar due to physical processing of the drill collar is avoided. Through the analysis of the principle model of delayed inverse excitation by a single sound source, the simulation calculation of the principle model and the processing of actual logging data by developing software based on adaptive filtering active noise control technology, it is verified that the new method has obvious effect on eliminating drill collar direct wave in acoustic logging while drilling.