Xiaoyue Cao

• Doctor of Geophysics
• Associate Professor at Yangtze University

Previous works have demonstrated that inverting MT data jointly with gravity data can synergize the high lateral resolution of gravity and the vertical resolution of MT. However, the existing joint stabilizers usually work for structured grids instead of unstructured ones that are more powerful for characterizing complex geology. Here, we utilize L...

The transient electromagnetic method (TEM) is widely used in the exploration of mineral, petroleum, and geothermal resources due to its sensitivity to low-resistivity bodies, limited site constraints, and strong resistance to interference. In practical applications, the TEM often uses a long wire source instead of an idealized horizontal electric d...

A long wire with large current source transient electromagnetic (TEM) monitoring, with a large detection depth, low cost, safety, and environmental protection, has unique advantages in the testing and identification of unconventional reservoir fluid and the evaluation of stimulated reservoir volume. So, the TEM 3D forward modeling method has become...

Airborne electromagnetic (AEM) surveys using airborne mobile platforms enable rapid and efficient exploration of areas where groundwork is difficult. They have been widely used in fields such as shallow resource exploration and environmental engineering. Three-dimensional AEM inversion is the main technique used in fine structural interpretation. H...

As an airborne electromagnetic method induced by natural sources, the Z-axis tipper electromagnetic (ZTEM) system can primarily recover near-surface shallow structures, due to band-limited frequencies (usually 30–720 Hz) of the airborne survey and high sample rate acquisition along the terrain. In contrast, traditional ground magnetotellurics (MT)...

Three dimensional gravity inversion is an effective way to extract subsurface density distribution from gravity data. Different from the conventional geophysics-based inversions, machine-learning-based inversion is a data-driven method mapping the observed data to a 3D model. We have developed a new machine-learning-based inversion method by establ...

Z-axis tipper electromagnetic (ZTEM) technique is an airborne electromagnetic method that detects anomalies in the deep earth that are induced by natural sources. Conven- tional ZTEM forward modeling is generally conducted using structured grids that have limited accuracy and cannot be used to invert complex underground structures and topography. H...

The spectral-element (SE) method, which is based on the Galerkin technique, has been gradually implemented in geophysical electromagnetic (EM) three-dimensional (3D) simulation. The accuracy and efficiency of this approach, implemented for both deformed hexahedral and regular meshes, has been verified for airborne EM forward modeling. One advantage...

The conventional 3D magnetotelluric (MT) forward modeling and inversions generally assume an isotropic earth model. However, wrong results can be obtained when using an isotropic model to interpret the data influenced by the anisotropy. To effectively model and recover the earth structures including anisotropy, we develop a 3D MT inversion framewor...

This paper presents a 3D forward modelling algorithm with an adaptive finite-element method based on unstructured grids that when used with a circular scanning DC measurement technique can provide an indication of anisotropy in a layered earth. The accuracy of this algorithm is checked against 1D semi-analytical solutions for an arbitrarily anisotr...

Spectral-element (SE) method is a kind of higher-order finite-element method based on weighted residual technique; however, the basis functions for SE are polynomial, like Gauss-Lobatto-Legendre (GLL) or Gauss-Lobatto-Chebyshev (GLC) polynomials. Because of its high modeling accuracy and flexibility, it has been successfully used in computational e...

Mainstream numerical methods for 3D time-domain airborne electromagnetic (AEM) modeling, such as the finite-difference (FDTD) or finite-element (FETD) methods, are quite mature. However, these methods have limitations in terms of their ability to handle complex geologic structures and their dependence on quality meshing of the earth model. We have...

Traditional 3D Magnetotelluric (MT) forward modeling and inversions are mostly based on structured meshes that have limited accuracy when modeling undulating surfaces and arbitrary structures. By contrast, unstructured-grid-based methods can model complex underground structures with high accuracy and overcome the defects of traditional methods, suc...

Traditional 3D Magnetotelluric (MT) forward modeling and inversions are mostly based on structured meshes that have limited accuracy when modeling undulating surfaces and arbitrary structures. By contrast, unstructured-grid-based methods can model complex underground structures with high accuracy and overcome the defects of traditional methods, suc...

Electrical anisotropy exists everywhere in nature that has become an important issue non-ignorable in geophysical exploration. Especially in areas of sedimentary rocks where strata in the earth result in variation of resistivity varying with the direction of current flow. In this paper, we review the research on electrical anisotropy in geo-electro...

Traditional 3D MT data interpretations are based on an isotropic model that is sometimes inappropriate, because it has been well established that electrical anisotropy is widely present in the deep earth. The MT anisotropic modelling is generally worked on structured meshes that has a limited accuracy but cannot model complex geology. We present a...

The airborne electromagnetic (AEM) method has a high sampling rate and survey flexibility. However, traditional numerical modeling approaches must use high-resolution physical grids to guarantee modeling accuracy, especially for complex geological structures such as anisotropic earth. This can lead to huge computational costs. To solve this problem...

Spectral element method (SE) is a kind of numerical simulation method based on weighted residual technique, whose interpolation functions are polynomials rather than linear functions. The polynomials have the characteristic of exponential convergence with the polynomial orders. This helps improve the computational accuracy. In this paper, we apply...