A study on pseudo-abnormality of all-time apparent resistivity for transient electromagnetic method

摘要

According to the expression of field in infinite homogeneous half-space, for transient electromagnetic method, the paper introduced the numerical method of all time apparent resistivity and smoke loop inversion. At the same time phenomenon of pseudo-abnormality was researched and analyzed which is of all time apparent resistivity. Theoretical data forwarded from typical layer model was used to test the validity of method of all time apparent resistivity, such as two, three and five layer models. The results show that the pseudo-abnormality is characterized by high resistivity, a defect of information is caused when try to find a low resistance body during the exploration, and pseudo-abnormality only present from early time to middle time during the transition, whereas there is no pseudo-abnormality in other times. Based on the character of pseudo-abnormality, it is proposed a method to eliminate pseudo-abnormality of all time apparent resistivity, smoke loop inversion was used to analyze the effect on inversion image from pseudo-abnormality which was eliminated by interpolation. The processing results of theoretical data were demonstrated at the end.