Research On Inversion Method Of Target Locating Based On Magnetic Anomaly

Magnetic survey is one of widely applicable geophysical exploration methods. It canmeasure the total field and the full tensor gradient field in three directions of Cartesiancoordinate system, which is of high-efficiency and high-precision. As a new geophysicalexploration tool, magnetic tensor measurement is gradually becoming a popular method ofmagnetic exploration, which can provide the tensor of the geologic body and delineate thefeature of the geologic bodies more correctly. The magnetic gradient tensor measurement isgradually used in the magnetic source localization and identification as its characteristics ofabundant information in different direction, such as concealed geological body detection,UXO detection, anti-submarine, etc. Realizing the spatial localization of target body is oneof main objectives of magnetic research. It is to realize high-accuracy and rapid locating oftarget body by researching the total magnetic and its gradient tensor data and the fieldinversion method.In the combination with current existing magnetic survey carry platforms, this paperanalyzes the research process of magnetic survey acquisition system, summarizes thedevelopment situation of aeromagnetic survey, marine geomagnetic survey, satellitemagnetic survey and magnetic gradient tensor measurement in detail, evaluates theadvantages and disadvantages between different systems, contrasts the research gap at homeand abroad, in order to improve integration capability and target detection ability ofmagnetic system, providing relevant reference for taking advantage of magnetic surveyinstrument within the effective precision and realizing multi-means, multi-way, rapidmeasurement.In this paper, magnetic survey data of Jinshan area is processed and interpretated so asto study the magnetic characteristic of shallow target. The research shows that median filterprocessing to the near-surface magnetic anomaly data is effective, and it keeps effectiveinformation of UXO anomaly data while eliminating the stripe of background noise. Inaddition, UX Parameter Determination module of Oasis Montaj is used to locate and labelthe suspected UXO target. This paper uses the improved Euler deconvolution method toinvert for the depth of extracted UXO anomaly data, constrained by the central area of UXO anomaly delineated by the analytic signal, calculating its average of inversion depth in thisarea, which improves the inversion accuracy.This paper conducts research on gradient tensor field single-point locating methodunder noise environment and multi-body condition, and it shows that probability analysis tomultipoint locating results can improve the accuracy of target localization under thecondition of high noise and multi-body, which solves the problem on divergence of locatingresults effectively. The paper applies this method to some marine magnetic survey datasuccessfully, and locates the spatial position of magnetic objects under water accurately.To improve the precision of boundary identification of magnetic gradient tensor data,this paper uses the method of gradient tensor eigenvalue and its vertical derivative offrequency domain to locate and identify the horizontal boundaries of magnetic target. Bycontrasting by the analytical signal method, Tilt-angle method and Theta method, thismethod presents boundary information more clearly and has good applicability under noiseenvironment. It can delineate the boundary position of Luzong volcanic basins well in themagnetic anomaly data processing of Anhui Luzong area.