基于信号相似性的导向钻井下传信号处理方法

为了准确、高效识别导向钻井中以钻井液排量负脉冲间隔方式下传的指令信号,解决井下接收装置中指令识别和解释方法运算较复杂和误码率较高等问题,提出了一种基于信号相似性原理的信号识别处理技术。该技术通过比较各段采样信号幅值的自相关程度求取由钻井液排量脉宽所表示的导向钻井下传指令,并对井下采样信号按一定规律逐段比较,通过判断信号下传的开始点、解算信号各位的值和求取指令字等3个步骤,完成指令识别。给出了适合井下处理的递推式实用算法,设计了钻井液排量信号采集试验装置。研究和试验结果表明,利用该方法可简化运算程序、提高钻井液排量信号识别的可靠性和抗扰能力,特别有利于克服尖峰和周期干扰对计时求取的影响以及传输通道惯性及低频噪音对信号跳变沿判断的影响。图4参15

A downward signal processing method for rotary steerable drilling system based on signal similarity

To identify downhole command signals accurately and efficiently with negative fluid pulse intervals in the rotary steerable drilling engineering and solve the complex operation and high error rate problems in the command identification and explanation process of downhole receivers, this paper presents a signal process method based on signal similarity principle. In this method, command instructions expressed by drilling fluid pulse width signal are obtained by comparing the self-correlation degree of sampling signal amplitudes at each interval, and the downhole sampling signals are compared interval by interval according to a fixed rule, and command identification is achieved by three steps, i.e. judgment for the start of signal, calculation for digital bits of the command, and assembling of command word. The recursive practical algorithms suitable for downhole processing are proposed. The results show that the method can simplify operation program and improve the reliability and ability of interference killing for the signal identification, and is especially good for overcoming the effects of peak and periodic interference on time counting and the effects of inertia of transmitting channel and low frequency noise on signal jump edge judging.