磁共振测深技术的发展历程与新进展

The development history and new progress of magnetic resonance sounding technique

磁共振测深(Magnetic Resonance Sounding,MRS)技术作为目前唯一能够实现地下水直接定量探测的地球物理高新技术已有近30年的历史,最近10年,MRS技术在仪器、正反演理论、信号影响因素、实际应用等方面都取得了一系列进展.死区时间不到10ms的商用型多道磁共振测深仪的推广使用,大幅改善了MRS方法的找水效果和仪器的抗干扰能力;正反演研究的重心已由简单的一维层状假设理论转入更符合实际情况的复杂地质条件下的高分辨率2/3D磁共振成像研究;信号影响因素与机制的研究也更加深入、全面;特别是实际应用方面,正在由单纯的地下水探测向水文地质调查、地下水管理与污染监测、灾害水源的超前探测等多个领域拓展.随着磁共振测深技术的进一步发展与完善,它定将在更多领域更好地造福于人类.

Magnetic Resonance Sounding （MRS） is a high and new geophysical technology which has been developed nearly 30 years. It＇s the first kind of geophysical method which can detect groundwater directly. In the last 10 years, MRS has obtained a series of new progress in instrument, forward and inversion theory, signal influence factors research, practical applications and some other aspects. With the wide spreading use of commercial multi-channel MRS equipment whose dead time are less than 10 ms, significantly improves MRS＇s ability of detecting underground water and anti-interference. Such as the multi-channel instrumentation GMR and its software, which is developed in the United States, has been applied to investigate 1D and 2D hydrology at various locations. The GMR instrument has an ultra-low receiver input noise density of less than 0.4 nV/sqrt（Hz）. Two multi-channel NMR processing techniques, reference coil-based noise cancellation and integrated FID imaging, are shown to increase effective signal to noise ratios by an order of magnitude or more. At present, one-dimensional inversions are the most common and mature type of SNMR inversion and are applicable to many hydrogeologic settings. The research emphasis of forward and inversion theory has been developed from simple one-dimensional layered hypothesis theory into high resolution 2/3D magnetic resonance tomography under complex geological conditions which is more in line with the actual situation. Signal influence factors and mechanism research have also become more intensive and comprehensive. In particular, the practical applications have been developed from mere groundwater detection to hydrogeology investigation, groundwater management and pollution monitoring, advanced detection of disaster water and some other fields, but some of these applications are still in the experimental research stage. With further developments and improvements of magnetic resonance sounding technique, it will better benefit our mankind in more fields definitely.