Aeromagnetic Gradient Data Processing And 3D Inversion Study

Aeromagnetic gradient data can eliminate diurnal variations problems, highlight the near-surface anomaly and better reflect the geological boundary and structure; in addition, transverse horizontal gradient can provide more geological information between survey flight lines. Test flight and production of AGS-863 all-axis aeromagnetic gradient survey system, which developed by China Aero Geophysical Survey & Remote Sensing Center for Land and Resources (AGRS), obtained about 18,000 km high-precision transverse horizontal gradient data, longitudinal horizontal gradient data and vertical gradient data. It has important meaning to apply these measured gradient data to solving practical problems.In this thesis, on the basis of the characteristic of aeromagnetic gradient data, the author studies the aeromagnetic gradient data processing and the 3D inversion method. The studies are as follows:(1) The principle and problems of total filed reconstruction from gradient data are discussed, and the method is put into the model data and measured data application.(2) Hardwick method and Nelson method are the main enhanced grid method. Through the application of measured gradient data, it’s proved that Nelson method can achieve better enhancement results.(3) The Nelson method is also achieved good levelling results. This method does not need the Tie line data, but should be used in the case of small altitude difference between flight lines.(4) Because gradient data can better reflect the geological boundary and highlight the near-surface anomaly, we can use gradient data into inversion to improve the inversion result. The application of depth weighting and sparse constraints techniques in the magnetic and magnetic gradient data 3D inversion achieved good inversion results. In addition, the vertical gradient data inversion can achieve a better result than total filed data inversion which with near-surface anomaly.