Producing magnetite and hematite alteration proxies using 3D gravity and magnetic inversion: method and results for the Tennant Creek-Mount Isa Project, northern Australia

2019 ◽  
Author(s):  
J.A. Goodwin ◽  
R.G. Skirrow
Keyword(s):  
Inversion Method ◽  
Northern Australia ◽  
Mount Isa ◽  
Gravity And Magnetic ◽  
Magnetic Inversion ◽  
3D Gravity

Magnetic inversion to recover the subsurface block structures based on L1 norm and total variation regularization

2021 ◽  
Author(s):  
Mitsuru Utsugi
Keyword(s):  
Total Variation ◽  
Magnetic Data ◽  
Preconditioned Conjugate Gradient ◽  
Inversion Method ◽  
Total Variation Regularization ◽  
Subsurface Structure ◽  
L1 Norm ◽  
Magnetic Inversion ◽  
Original Definition ◽  
Primal Dual

Summary This paper presents a new sparse inversion method based on L1 norm regularization for 3D magnetic data. In isolation, L1 norm regularization yields model elements which are unconstrained by the input data to be exactly zero, leading to a sparse model with compact and focused structure. Here, we complement the L1 norm with a penalty minimizing total variation, the L1 norm of the model gradients; it is expected that the sharp boundaries of the subsurface structure are not compromised by incorporating this penalty. Although this penalty is widely used in the geophysical inversion studies, it is often replaced by an alternative quadratic penalty to ease solution of the penalized inversion problem; in this study, the original definition of the total variation, i.e., form of the L1 norm of the model gradients, is used. To solve the problem with this combined penalty of L1 norm and total variation, this study introduces alternative direction method of multipliers (ADMM), which is a primal-dual optimization algorithm that solves convex penalized problems based on the optimization of an augmented Lagrange function. To improve the computational efficiency of the algorithm to make this method applicable to large-scale magnetic inverse problems, this study applies matrix compression using the wavelet transform and the preconditioned conjugate gradient method. The inversion method is applied to both synthetic tests and real data, the synthetic tests demonstrate that, when subsurface structure is blocky, it can be reproduced almost perfectly.

The Implementation of Visualization Software of the Rapid 3D Apparent Physical Properties Inversion Method

2013 ◽  
Vol 734-737 ◽  
pp. 3026-3029
Author(s):  
Hai Xia Li ◽  
Hai Long Yu ◽  
Ping Chuan Zhang
Keyword(s):  
Physical Properties ◽  
Potential Field ◽  
Implementation Process ◽  
Inversion Method ◽  
Main Function ◽  
Dynamic Link Library ◽  
Software Interface ◽  
Visualization Software ◽  
Magnetic Inversion ◽  
Key Techniques

The main function of the application software of the rapid inversion method of 3D apparent physical properties, and the key techniques used to achieve software are described in this paper. The core modules of the software is apparent physical properties inversion which can achieve the 3D apparent density and the 3D apparent magnetic inversion calculation, in addition, the software provides data preprocessing, reduction to the pole, the potential field continuation and potential field cut function. In software implementation process, first, compiling the calculation program modules by Fortran90 language, and then combining with dynamic link library, multi-threading and Surfer automated call technology, we compiled the visualization software interface to realize the function of the new method by C, C + + language, under the C + + Builder6.0 environment.

Integration of gravity, magnetic, and seismic data for subsalt modeling in the Northern Red Sea

2021 ◽  
Vol 9 (2) ◽  
pp. T507-T521
Author(s):  
Camille Le Magoarou ◽  
Katja Hirsch ◽  
Clement Fleury ◽  
Remy Martin ◽  
Johana Ramirez-Bernal ◽  
...  
Keyword(s):  
Red Sea ◽  
Seismic Reflection ◽  
Magnetic Data ◽  
Gravity Inversion ◽  
Gravity And Magnetic ◽  
3D Gravity ◽  
Thin Crust ◽  
Gravity And Magnetic Data ◽  
Refraction Data ◽  
Northern Red Sea

Rifts and rifted passive margins are often associated with thick evaporite layers, which challenge seismic reflection imaging in the subsalt domain. This makes understanding the basin evolution and crustal architecture difficult. An integrative, multidisciplinary workflow has been developed using the exploration well, gravity and magnetics data, together with seismic reflection and refraction data sets to build a comprehensive 3D subsurface model of the Egyptian Red Sea. Using a 2D iterative workflow first, we have constructed cross sections using the available well penetrations and seismic refraction data as preliminary constraints. The 2D forward model uses regional gravity and magnetic data to investigate the regional crustal structure. The final models are refined using enhanced gravity and magnetic data and geologic interpretations. This process reduces uncertainties in basement interpretation and magmatic body identification. Euler depth estimates are used to point out the edges of high-susceptibility bodies. We achieved further refinement by initiating a 3D gravity inversion. The resultant 3D gravity model increases precision in crustal geometries and lateral density variations within the crust and the presalt sediments. Along the Egyptian margin, where data inputs are more robust, basement lows are observed and interpreted as basins. Basement lows correspond with thin crust ([Formula: see text]), indicating that the evolution of these basins is closely related to the thinning or necking process. In fact, the Egyptian Northern Red Sea is typified by dramatic crustal thinning or necking that is occurring over very short distances of approximately 30 km, very proximal to the present-day coastline. The integrated 2D and 3D modeling reveals the presence of high-density magnetic bodies that are located along the margin. The location of the present-day Zabargad transform fault zone is very well delineated in the computed crustal thickness maps, suggesting that it is associated with thin crust and shallow mantle.

8. Seismic-Reflection Imaging of the Environment around the Mount Isa Orebodies, Northern Australia: A Case Study

2003 ◽  
pp. 127-138 ◽  
Author(s):  
B. J. Drummond ◽  
A. J. Owen ◽  
J. C. Jackson ◽  
B. R. Goleby ◽  
S. N. Sheard
Keyword(s):  
Seismic Reflection ◽  
Northern Australia ◽  
Mount Isa ◽  
Reflection Imaging

3D Real-Time Modeling Issue in Gravity & Magnetic Anomalies Interpretation Tool

2011 ◽  
Vol 271-273 ◽  
pp. 495-500
Author(s):  
Jiang Ning Yin ◽  
Dun Hui Xiao
Keyword(s):  
3D Models ◽  
Magnetic Anomalies ◽  
Three Dimension ◽  
Forward Algorithm ◽  
New Approach ◽  
Time Modeling ◽  
Gravity And Magnetic ◽  
Geological Models ◽  
Interpretation System ◽  
3D Gravity

We present a new approach for constructing the initial 3D geological models in the process of man-machine interactive interpretation for gravity and magnetic anomalies. Firstly, we introduced the steps of method. It includes some auxiliary vertexes and sections techniques. Then, the forward algorithm of the model is given. And the data structure of the model is devised, later the modifying method and visualization method is discussed. This method is realized in our 3D gravity & magnetic anomaly interpretation system based on VC++6.0 and OpenGL. Using this method, the geophysical interpreter can construct or modify the geological models easily under the three dimension environment. The tool can give them visual 3D models, so it enhances the efficiency of the interpretation.

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