瞬变电磁测井信号自适应相干积累检测方法

摘要

The low signal-to-noise ratio (SNR) is one of the main factors which affected the development of borehole transient electromagnetic system due to the complicated measurement conditions such as high temperature,high pressure and motion measurement.Aiming at this problem,an adaptive coherent integration detection method for borehole transient electromagnetic systems is presented based on the cylindrically multi-layered inhomogeneous model.The method utilizes the correlation of transient electromagnetic response of the adjacent periods in motion measurement and achieves the adaptive length coherent integration by calculating the Frobenius norm of the difference of response in different periods.Field experiment results demonstrate that the proposed method can effectively improve the SNR of borehole transient electromagnetic system.Comparing to the fixed length coherent integration,the proposed method can adapt to the borehole environment much better.%受井下高温、高压以及运动测量等复杂测试条件的影响,低信噪比一直是困扰井下瞬变电磁探测系统发展的主要因素之一.针对这一问题,在柱状多层非均匀模型基础上,提出了一种瞬变电磁测井信号自适应相干积累检测方法.利用运动测量过程中相邻周期瞬变电磁响应的相关性,通过计算不同周期响应差异的Frobenius范数实现自适应相干积累.现场试验结果分析表明,该方法能够有效改善井下瞬变电磁系统信噪比,比固定时间相干积累具有更好的井下复杂环境适应能力.