Surface Nuclear Magnetic Resonance Forward And Inversion Research

With the rapid development of China's economy and the continuous improvement of people's living standards, industrial and agricultural water demand has increased year by year, water supply and demand situation brings our country greater pressure, especially in the large and medium-sized cities in north of China, water resources becomes a major constraint of local economic development. Groundwater resources occupy a pivotal position in our country's water resources, for its wide distribution, good quality, be contaminated difficultly, and a high degree of assurance of water supply, it being used and developed more and more widely.Nuclear magnetic resonance is developed very rapidly in recent years, it was earliest used in medical perspective, in the past 10 years, geophysicists pay attention to it, and then it was applied in geophysical exploration. As the only directly detecting groundwater geophysical method, for its low cost and good effect in detecting water, it was more and more widely used in groundwater resources detecting in the worlds that no water or water-deficient area's.At present, Legchenko, A., Yaramanci, U., Weichan, P.B., as the representative of Hesperian scientists, are actively carrying out research and development work in this field, And they have achieved considerable results. one-dimensional nuclear magnetic resonance forward and inversion have been more and more mature after the past few years research and innovation. They developed the inverse method from inverse the initial water content purely using amplitude to extract underground resistivity join with nuclear magnetic resonance phase, it changed the idea that we must detect the underground resistivity before we use surface nuclear magnetic resonance prospect for water in the past.Inland research in the field is main focus at the discussions of the validity of this method. Except Weng Aihua of jilin university has published several articles in the field, there is no expert that dedicating in theoretical study. Surface nuclear magnetic resonance inverse theory is still in the stage of attempt, there is a definite distance between present level and the goal that hold homemade forward and inverse software we look forward.This paper consists mainly of six chapters.Chapter one is the exordium. It includes: intention and significance of this course of study; current progress and problems in forward and inversion at home and abroad; research target, research content and key problems solved; technical ways and means; several originalities in the research process.Chapter two simply introduced the basic principles of nuclear magnetic resonance. It mainly includes lamoer precession,the movement of M in the alternating magnetic field and measurement parameters and inverse parameters of surface nuclear magnetic resonance.Chapter three deduced in detail and discussed the vertical excitation field. It mainly includes excitation electromagnetic field underground that produced by large loop source; using Chave algorithm in integrating function contains bessel function; discussed the influence of geomagnetic obliquity angle,geomagnetic declination angle,conductivity of the medium underground to vertical excitation field intensity and phase.Chapter four is the surface nuclear magnetic resonance forward theoretical research. Presents in detail surface nuclear magnetic resonance forward theory,calculation methods; numerical simulated nuclear magnetic resonance toppled angle,3D kernel function,1D kernel function, discussed the relationship between them and excitation pulse, underground medium conductivity, depth and so on; we calculated the initial amplitude separately by conventional methods and simple model; discussed the factors that influenced nuclear magnetic resonance initial amplitude.Chapter five is the surface nuclear magnetic resonance inversion theoretical research. In the circumstances that the media conductivity is bad, we separately made inversion research of theoretical observational data and the theoretical observation data added Gaussian random noise using singular value decomposition method; improved simulated annealing algorithm, combined Regional idea to simulated annealing algorithm; we separately made inverse experimentation of theoretical observational data and the theoretical observation data added Gaussian random noise using improved simulated annealing algorithm, validated the feasibility of inverse surface nuclear magnetic resonance aquifer parameters using improved simulated annealing algorithm.Chapter six arrives at some conclusions. Meanwhile, the remaining problems of this method and researches to be done had been discussed, as well as prospects for future development and application.Surface nuclear magnetic resonance is a young geophysical methods, research and development space is broad. Because it is a foreland with interdisciplinary intercross exploration technology, the development of this technology is influenced by physical Science,engineering hydrogeology,rock physics,measurement and control technology,software technology,and so on. In order to make surface nuclear magnetic resonance serving us better, we must improve the associated disciplines which also decides that its future development road will be long and tortuous. But we firmly believe that surface nuclear magnetic resonance theory is improving daily with the surface nuclear magnetic resonance study continuous development, and it will increasingly demonstrate its strong vitality and make its own contribution to the development of today's earth science.