Research On Forward And Inversion Of Nuclear Magnetic Resonance For Water Exploration

Nuclear Magnetic Resonance (NMR) is a sophisticated technology today, as it has been broadly applied in the areas of physics and medicine science. The lossless and the high-resolution are the most important advantage of NMR. Using NMR for water exploration is a new field of application in geoscience, and it inspires a new way for Geophysics. Although NMR for water exploration has made lots of breakthrough and progress from its birth to now, there are many obvious deficiencies still. This requires us to participate the learning and researching of the method.This dissertation is based on the theory of NMR. First of all, simulated forward calculation is done for horizontal water-saturated layer model in the condition of half space and homogeneous medium, and the elements that influence NMR signals are tested and analyzed detailedly. Then, moisture content inversion of the model is done by regularization methods. So we can analyze the feasibility and the accuracy of the Tikhonov Regularization algorithm and the Least Squares with a Quadratic Constraint algorithm by the results of inversion. Based on the inversion, we focus on the ways to improve the depth of exploration, and the testing is done by increasing exciting pulse moment and uniform magnetic field. The test proves that it is feasible to improve the depth of exploration by means of increasing exciting pulse moment, and the method which improves exploration depth by means of increasing uniform magnetic field needs further research.