The magnetotelluric (MT) sounding of a layered Earth model involving a transitional layer has been widely studied, and MT responses of the model with dipping anisotropic conductivity have also been treated. However, a model incorporating both a transitional layer and dipping anisotropy has seldom been considered. The analytical solution of such a geoelectrical model including three layers was derived in this study. The middle layer was a transitional layer with conductivity exponentially varying with depth, which was covered by a homogeneous layer and underlaid by a dipping anisotropic half-space. The electromagnetic (EM) fields in the transitional layer were explicitly solved with modified Bessel functions. The surface impedance was calculated recursively. The dependence of the apparent resistivity and impedance phase as well as the EM fields on different model parameters were investigated in detail. We believe that our analytical solution provides a useful complement to the theory of the one-dimensional (1D) inversion and interpretation based on the layered model with fixed conductivity.

The complex topography of deep sea presents numerous challenges for the accurate exploration of sub-bottom profiles. These include real-time tracking of seafloor reflectors, acquisition and storage of deep-sea long-term reflection data, and splicing of successive profiles. Based on the actual survey data of deep sea, we have developed automatic positioning and noise suppression algorithms, namely the double-difference threshold of proximity points. Furthermore, we have created automatic algorithms, namely content expansion and group data moving, based on extremum in seafloor’s depth. These have been designed to automatically suppress the random noise and effectively splice the sub-bottom profile data in deep water. The aforementioned processing techniques facilitate the enhancement of the quality of deep-water sub-bottom profile data, thereby enabling the provision of a comprehensive and successively long profile for interpretation in the context of deep-water sub-bottom profile data.

Time-depth conversion is a critical stage in the geological interpretation of reflection seismic data, as its precision determines the accuracy of structural interpretation at reflective interfaces and geological profile products. The fidelity primarily depends on accurate stratigraphic velocity definition and the conversion method. Conventional velocity modeling for oilfield data heavily relies on logging data, while single-average velocity conversion lacks accuracy in complex lithological formations. Existing technologies struggle to balance between “modeling cost” and “conversion accuracy”. To address this challenge, this paper proposes a novel time-depth conversion strategy at the interpretation-level output stage. This method abandons direct full-time domain resampling. Instead, focusing on the interpreted reflectors, it constructs a layer velocity input interface and employing a layer-by-layer stripping and cumulative thickness algorithms, it achieves refined conversion and output for these layers only, avoiding full dataset processing. Application of this method to interpret actual reflection data from a maritime area significantly reduced the computational complexity of time-depth conversion while enhancing computational efficiency, it also eliminated structural distortions caused by seafloor topographic undulations, effectively improving interpretation accuracy. Practical application demonstrates the method’s utility and efficiency in deepwater environments and complex geological conditions lacking well control, providing a new low-cost, high-precision geological pathway.