In recent years, the anisotropic study has become a hot topic in the field of electromagnetics. Currently, inversion technologies of transient electromagnetic sounding data are mainly based on the case of an isotropic...In recent years, the anisotropic study has become a hot topic in the field of electromagnetics. Currently, inversion technologies of transient electromagnetic sounding data are mainly based on the case of an isotropic medium. However, the actual underground electrical structure tends to be complicated and anisotropic. It is often found that the isotropic inversion technologies do not lead to good results for field transient electromagnetic sounding data. We have developed an algorithm for calculating the transient electromagnetic response in a layered medium with azimuthal anisotropy. An occam inversion algorithm has also been implemented to invert the transient electromagnetic data induced by a grounded horizontal electric dipole in a layered medium with azimuthal anisotropy. Synthetic examples demonstrate the stability and validity of the inversion algorithm. Experimental results show different data for inverting have great influence on the inversion results.展开更多
As geological exploration conditions become increasingly complex, meeting the requirements of precise geological exploration necessitates the development of a controlled-source audio magnetotelluric (CSAMT) inversion ...As geological exploration conditions become increasingly complex, meeting the requirements of precise geological exploration necessitates the development of a controlled-source audio magnetotelluric (CSAMT) inversion method that considers anisotropy to improve the effectiveness of inversion accuracy and interpretation accuracy of data. This study is based on the 3D fi nite-diff erence forward modeling of axis anisotropy using the reciprocity theorem to calculate the Jacobian matrix by applying the search method to automatically search for the Lagrange operator. The aim is to establish inversion iteration equations to achieve the axis anisotropic Occam's 3D inversion of tensor CSAMT in data space. Further, we obtain an underground axis anisotropic 3D geoelectric model by inverting the impedance data of tensor CSAMT. Two synthetic data examples show that using the isotropic tensor CSAMT algorithm to directly invert data in anisotropic media can generate false anomalies, leading to incorrect geological interpretations. Meanwhile, the proposed anisotropic inversion algorithm can eff ectively improve the accuracy of data inversion in anisotropic media. Further, the inversion examples verify the eff ectiveness and stability of the algorithm.展开更多
Geological structures often exhibit smooth characteristics away from sharp discontinuities. One aim of geophysical inversion is to recover information about the smooth structures as well as about the sharp discontinui...Geological structures often exhibit smooth characteristics away from sharp discontinuities. One aim of geophysical inversion is to recover information about the smooth structures as well as about the sharp discontinuities. Because no specific operator can provide a perfect sparse representation of complicated geological models, hyper-parameter regularization inversion based on the iterative split Bregman method was used to recover the features of both smooth and sharp geological structures. A novel preconditioned matrix was proposed, which counteracted the natural decay of the sensitivity matrix and its inverse matrix was calculated easily. Application of the algorithm to synthetic data produces density models that are good representations of the designed models. The results show that the algorithm proposed is feasible and effective.展开更多
In Dangjialiang area of Ningqiang County, the terrain is severely cut, the vegetation is relatively developed, and the covering layer is relatively thick. In order to carry out geothermal resources exploration, the au...In Dangjialiang area of Ningqiang County, the terrain is severely cut, the vegetation is relatively developed, and the covering layer is relatively thick. In order to carry out geothermal resources exploration, the author obtains two-dimensional apparent resistivity model of audio magnetotelluric sounding profile by two-dimensional inversion of TM model of 74 sounding points in two audio magnetotelluric sounding profiles. The inversion result shows that that stratigraphic-lithologic boundary and fault structure location shown in section AA are basically consistent with those shown in section BB. This audio-frequency magnetotelluric sounding survey has completed the division of stratigraphic sequences and fault structures in the areas controlled by the exploration lines, delineated the favorable geothermal resources storage scope in the study area, and given the well location arrangement suggestions, which provide the basic basis for the later exploration and development.展开更多
文摘In recent years, the anisotropic study has become a hot topic in the field of electromagnetics. Currently, inversion technologies of transient electromagnetic sounding data are mainly based on the case of an isotropic medium. However, the actual underground electrical structure tends to be complicated and anisotropic. It is often found that the isotropic inversion technologies do not lead to good results for field transient electromagnetic sounding data. We have developed an algorithm for calculating the transient electromagnetic response in a layered medium with azimuthal anisotropy. An occam inversion algorithm has also been implemented to invert the transient electromagnetic data induced by a grounded horizontal electric dipole in a layered medium with azimuthal anisotropy. Synthetic examples demonstrate the stability and validity of the inversion algorithm. Experimental results show different data for inverting have great influence on the inversion results.
基金supported by Heilongjiang Province Basic Research Business Expenses for Universities Heilongjiang University Special Fund Project (Grant No. 2023-KYYWF-1494)the Natural Science Foundation of Jiangxi Province (Grant No. 20212BAB213023)。
文摘As geological exploration conditions become increasingly complex, meeting the requirements of precise geological exploration necessitates the development of a controlled-source audio magnetotelluric (CSAMT) inversion method that considers anisotropy to improve the effectiveness of inversion accuracy and interpretation accuracy of data. This study is based on the 3D fi nite-diff erence forward modeling of axis anisotropy using the reciprocity theorem to calculate the Jacobian matrix by applying the search method to automatically search for the Lagrange operator. The aim is to establish inversion iteration equations to achieve the axis anisotropic Occam's 3D inversion of tensor CSAMT in data space. Further, we obtain an underground axis anisotropic 3D geoelectric model by inverting the impedance data of tensor CSAMT. Two synthetic data examples show that using the isotropic tensor CSAMT algorithm to directly invert data in anisotropic media can generate false anomalies, leading to incorrect geological interpretations. Meanwhile, the proposed anisotropic inversion algorithm can eff ectively improve the accuracy of data inversion in anisotropic media. Further, the inversion examples verify the eff ectiveness and stability of the algorithm.
基金Projects(41174061,41374120)supported by the National Natural Science Foundation of China
文摘Geological structures often exhibit smooth characteristics away from sharp discontinuities. One aim of geophysical inversion is to recover information about the smooth structures as well as about the sharp discontinuities. Because no specific operator can provide a perfect sparse representation of complicated geological models, hyper-parameter regularization inversion based on the iterative split Bregman method was used to recover the features of both smooth and sharp geological structures. A novel preconditioned matrix was proposed, which counteracted the natural decay of the sensitivity matrix and its inverse matrix was calculated easily. Application of the algorithm to synthetic data produces density models that are good representations of the designed models. The results show that the algorithm proposed is feasible and effective.
文摘In Dangjialiang area of Ningqiang County, the terrain is severely cut, the vegetation is relatively developed, and the covering layer is relatively thick. In order to carry out geothermal resources exploration, the author obtains two-dimensional apparent resistivity model of audio magnetotelluric sounding profile by two-dimensional inversion of TM model of 74 sounding points in two audio magnetotelluric sounding profiles. The inversion result shows that that stratigraphic-lithologic boundary and fault structure location shown in section AA are basically consistent with those shown in section BB. This audio-frequency magnetotelluric sounding survey has completed the division of stratigraphic sequences and fault structures in the areas controlled by the exploration lines, delineated the favorable geothermal resources storage scope in the study area, and given the well location arrangement suggestions, which provide the basic basis for the later exploration and development.
