加权数字相敏检波算法在核磁共振测井数据采集中的应用

Application of Weighted Digital Phase-Sensitivity Detection Algorithm in Nuclear Magnetic Resonance Logging Data Acquisition

在核磁共振测井数据采集过程中,常采用数字相敏检波算法提取自旋回波的幅度和相位,但是该算法基于累加平均原理,使得包络状的自旋回波幅度采集结果偏低。创新性提出加权数字相敏检波算法,通过引入加权系数,提高包络峰值数据的权重,可有效提高核磁共振回波信号的测量精度,从而提高核磁共振测量的准确性。数值模拟和实验结果表明,在相同采集参数条件下,加权数字相敏检波算法与数字相敏检波算法的信噪比一致,前者比后者幅值计算准确性提高12%。该技术已应用于多频核磁共振测井仪,取得了良好的应用效果。

In the process of nuclear magnetic resonance(NMR)logging data acquisition,digital phase-sensitivity detection(DPSD)algorithm is often used to extract the amplitude and phase of spin echo,but this algorithm is based on the principle of cumulative average,which makes the acquisition result of envelope spin echo amplitude low.In this paper,weighted digital phase-sensitivity detection(WDPSD)algorithm is proposed.By introducing the weighting coefficient,the weight of envelope peak data can be increased,which can effectively improve the measurement accuracy of NMR echo,so as to improve the accuracy of NMR measurement.Numerical simulation and experimental results show that signal to noise ratio of WDPSD algorithm is consistent with which of DPSD algorithm under the same acquisition parameters,and the amplitude accuracy of WDPSD algorithm is 12%higher than which of DPSD algorithm.This technology has been applied to multi-frequency magnetic resonance logging tool(MRT)and achieved good results.