随钻测井数据声波遥传系统研究

摘要

LWD data transmission is one of the key technologies for achieving intelligent drilling.Acoustic wave wireless transmission tech-nology is a kind of LWD data transmission technologies.It takes the e lastic waves propagating along the drill string as carrier to transmit measure data to the ground.And it is an emerging,promising technology for LWD data distance transmission. However,acoustic noise,being generated during drilling by the drilling equipment and mud circulation,and signal attenuation in the transmission medium and especially the high reflectivity of the pipe joints caused the impulse response of the drill string lasts for hundreds of milliseconds.All those can cause serious InterSymbol Interference and eventually lead to the transmission capacity of the channel dropped significantly.To address this problem,after deeply analyzing the sound propagation characteristics of the drill string,project team proposes a transmission technology based on SC-FDE tech nology.ln order to improve the reliability and reduce the error rate of data transmission,we studied the channel coding/decoding technology and signal modulation/demodulation techniques that suitable for acoustic transmission channel characteristics.%随钻测井数据传输是实现智能化钻井的荚键技术之一，声波遥传技术是利用沿钻柱系统传播的弹性波为载波，将测量数据传输到地面的一种随钻数据传输技术，是一种新兴的、非常有发展前途的随钻数据遥传技术。然而，钻井过程中由钻井设备、泥浆的循环等产生的声波噪声以及信号在介质中传播的衰减吸收，特别是钻杆接头的高反射性，使得钻柱的脉冲响应持续达数酉毫秒，这将造成严重的码间干扰，并最终导致信道的传输能力的大幅下降。针对这一难题，该文在深入分析钻柱系统的声传播特性的基础上，提出基于SC—FDE技术的声波无线传输通信系统模型，并研究适合于声波传输信道特性的信道编译码技术以及随钻数据的调制解调技术，降低误码率、提高传输的可靠性。