考虑介质导电性影响的核磁共振一维正反演研究

One-dimensional modeling and inversion of nuclear magnetic resonance over electrically conductive medium

为避免地层导电性对核磁共振解释的影响,实现了考虑层状导电介质影响下的核磁共振一维正反演。利用层状导电介质的频域磁场响应对核磁共振激发磁场进行计算,求解过程中对核函数进行了改造,降低了其震荡性,使积分更容易实现,在此基础上实现了考虑电性影响的核磁共振一维正演。在反演解释方面,借助瞬变电磁法给出地电断面,利用超平面拟合算法实现了含水层含水率参数反演。将反演结果与商用软件反演结果进行对比,计算结果基本一致,且本研究算法具有更好的分层效果。

A 1 D （one-dimensional）nuclear magnetic resonance （NMR）modeling and inversion method was proposed, which considered the influence of conductive layered media.The NMR exciting magnetic field was calculated with the frequency domain magnetic field response of layered conductive media.The kernel function was modified in the calcula-tion process and the oscillation was thereby reduced,which made it easier in integration.The 1 D NMR modeling con-sidering the influence of conductivity was implemented based on the above technique.For the inversion interpretation, the inversion of water content parameter of water-bearing layers was implemented with hyper plane fitting technique after the geoelectric section was derived from TEM （transient electromagnetic method）.The inversion results were basically the same as those derived from commercial software.And the inversion results of the proposed method give more infor-mation on stratification.