基于时延差分的连续波随钻测量信号提取算法

连续波随钻测量技术具有信息上传速率高、信号发生器实现方便等优点,成为业内关注的热点。但是,与传统的正/负泥浆脉冲信号相比,由于连续波信号本质特性和载波信号形态的改变等因素使得这一载波信号在传输通道中的反射、叠加和回响更加剧烈,造成了信号的畸变,使得井下随钻测量信息的有效提取变得困难。针对上述造成信号畸变的原因,首先建立了井下钻具组合通道连续波信号传输的阻抗模型,随后分析了信号在不同钻具组合短节传输过程中的反射和叠加特性;并基于时延差分原理,推导出了基于时延差分的连续波随钻测量信号提取算法。完成理论分析之后,在实验井的连续波随钻测量工程钻井过程中应用本文提出的算法,实现了随钻测量信息的有效提取,消除了信号传输过程中的畸变。

Continues wave measurement while drilling signal extraction method based on time delay differentiation algorithm

The Continues Wave Measurement While Drilling (MWD) technique has so many advantages such as high data speed and simple structure so that it develops very quickly recently. On the other hand, because of the fundamental difference between the continues wave with positive and negative pulse signal, affection of the echo and reflection is aggravated that is created during the signal propagating in the Bottom Hole Assembly (BHA). So, it is very difficult to recovery the original signal and to abstract the MWD information. This paper describes a novel method to solve the above problems. Continues wave impedance characteristic is analyzed in detail, which is related to the BHA structure, and mathematic model is setup that reflects signal reflection and overlap during the propagation in the different part of the BHA. Based on the signal time delay differentiation algorithm, carrier signal extraction algorithm is derived step by step. Finally, the method is applied in the oil well drilling, and the correction and effectiveness of the algorithm is improved by the result.