scholarly journals Three-Dimensional Regularized Focusing Migration: A Case Study from the Yucheng Mining Area, Shandong, China

Minerals ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 471
Author(s):  
Yidan Ding ◽  
Guoqing Ma ◽  
Shengqing Xiong ◽  
Haoran Wang
Keyword(s):  
Large Scale ◽  
Mineral Exploration ◽  
Gravity Data ◽  
Three Dimensional ◽  
Mining Area ◽  
Model Parameters ◽  
Step Size ◽  
Migration Direction ◽  
Migration Imaging ◽  
Imaging Results

Gravity migration is a fast imaging technique based on the migration concept to obtain subsurface density distribution. For higher resolution of migration imaging results, we propose a 3D regularized focusing migration method that implements migration imaging of an entire gravity survey with a focusing stabilizer based on regularization theory. When determining the model parameters, the iterative direction is chosen as the conjugate migration direction, and the step size is selected on the basis of the Wolfe–Powell conditions. The model tests demonstrate that the proposed method can improve the resolution and precision of imaging results, especially for blocky structures. At the same time, the method has high computational efficiency, which allows rapid imaging for large-scale gravity data. It also has high stability in noisy conditions. The developed novel method is applied to interpret gravity data collected from the skarn-type iron deposits in Yucheng, Shandong province. Migration results show that the depth of the buried iron ore in this area is 750–1500 m, which is consistent with the drilling data. We also provide recommendations for further mineral exploration in the survey area. This method can be used to complete rapid global imaging of large mining areas and it provides important technical support for exploration of deep, concealed deposits.

scholarly journals Three-Dimensional Magnetic Inversion Based on an Adaptive Quadtree Data Compression

2020 ◽  
Vol 10 (21) ◽  
pp. 7636
Author(s):  
Dandan Jiang ◽  
Zhaofa Zeng ◽  
Shuai Zhou ◽  
Yanwu Guan ◽  
Tao Lin ◽  
...  
Keyword(s):  
Data Compression ◽  
Large Scale ◽  
Mineral Exploration ◽  
Three Dimensional ◽  
Original Data ◽  
Magnetic Data ◽  
The Best Approximation ◽  
Magnetic Inversion ◽  
Iterative Inversion ◽  
Computationally Intensive

Three-dimensional magnetic inversion allows the distribution of magnetic parameters to be obtained, and it is an important tool for geological exploration and interpretation. However, because of the redundancy of the data obtained from large-scale investigations or high-density sampling, it is very computationally intensive to use these data for iterative inversion calculations. In this paper, we propose a method for compressing magnetic data by using an adaptive quadtree decomposition method, which divides the two-dimensional data region into four quadrants and progressively subdivides them by recursion until the data in each quadrant meets the regional consistency criterion. The method allows for dense sampling at the abnormal boundaries with large amplitude changes and sparse sampling at regions with small amplitude changes, and achieves the best approximation to the original data with the least amount of data, thus retaining more anomalous information while achieving the purpose of data compression. In addition, assigning values to the data in the quadrants using the averaging method is essentially equivalent to average filtering, which reduces the noise of the magnetic data. Testing the synthetic model and applying the method to mineral exploration a prove that it can effectively compress the magnetic data and greatly improve the computational efficiency.

scholarly journals DebrisInterMixing-2.3: a finite volume solver for three-dimensional debris-flow simulations with two calibration parameters – Part 2: Model validation

2017 ◽  
Author(s):  
Albrecht v. Boetticher ◽  
Jens M. Turowski ◽  
Brian W. McArdell ◽  
Dieter Rickenmann ◽  
Marcel Hürlimann ◽  
...  
Keyword(s):  
Debris Flow ◽  
Model Validation ◽  
Material Properties ◽  
Large Scale ◽  
Fluid Dynamic ◽  
Three Dimensional ◽  
Clay Content ◽  
Friction Angle ◽  
Angle Of Repose ◽  
Model Parameters

Abstract. Here we present validation tests of the fluid dynamic solver presented in in v. Boetticher et al. (2016), simulating both laboratory-scale and large-scale debris-flow experiments. The new solver combines a Coulomb viscosplastic rheological model with a Herschel-Bulkley model based on material properties and rheological characteristics of the analysed debris flow. For the selected experiments in this study, all necessary material properties were known – the content of sand, clay (including its mineral composition) and gravel (including its friction angle) as well as the water content. We show that given these measured properties, two model parameters are sufficient for calibration, and a range of experiments with different material compositions can be reproduced by the model without recalibration. One calibration parameter, the Herschel–Bulkley exponent, was kept constant for all simulations. The model validation focuses on different case studies illustrating the sensitivity of debris flows to water and clay content, channel curvature, channel roughness and the angle of repose. We characterize the accuracy of the model using experimental observations of flow head positions, front velocities, run-out patterns and basal pressures.

scholarly journals Estimating Caprock Impact on CO2 Migration in the Gassum Formation Using 2D Seismic Line Data

2021 ◽  
Author(s):  
Odd Andersen ◽  
Anja Sundal
Keyword(s):  
Seismic Data ◽  
Large Scale ◽  
Flow Simulation ◽  
Small Scale ◽  
Model Parameters ◽  
Seismic Line ◽  
Migration Direction ◽  
3D Data ◽  
And Migration ◽  
The Impact

AbstractRealizable CO2 storage potential for saline formations without closed lateral boundaries depends on the combined effects of physical and chemical trapping mechanisms to prevent long-term migration out of the defined storage area. One such mechanism is the topography of the caprock surface, which may retain CO2 in structural pockets along the migration path. Past theoretical and modeling studies suggest that even traps too small to be accurately described by seismic data may play a significant role. In this study, we use real but scarce seismic data from the Gassum Formation of the Norwegian Continental shelf to estimate the impact of topographical features of the top seal in limiting CO2 migration. We seek to estimate the amount of macro- and sub-scale trapping potential of the formation based on a few dozen interpreted 2D seismic lines and identified faults. We generate multiple high-resolution realizations of the top surface, constructed to be faithful to both large-scale topography and small-scale statistical properties. The structural trapping and plume retardation potential of these top surfaces is subsequently estimated using spill-point (static) analysis and dynamical flow simulation. By applying these techniques on a large ensemble of top surface realizations generated using a combination of stochastic realizations and systematic variation of key model parameters, we explore the range of possible impacts on plume advancement, physical trapping and migration direction. The stochastic analysis of trapping capacity and retardation efficiency in statistically generated, sub-seismic resolution features may also be applied for surfaces generated from 3D data.

scholarly journals DebrisInterMixing-2.3: a finite volume solver for three-dimensional debris-flow simulations with two calibration parameters – Part 2: Model validation with experiments

2017 ◽  
Vol 10 (11) ◽  
pp. 3963-3978 ◽  
Author(s):  
Albrecht von Boetticher ◽  
Jens M. Turowski ◽  
Brian W. McArdell ◽  
Dieter Rickenmann ◽  
Marcel Hürlimann ◽  
...  
Keyword(s):  
Debris Flow ◽  
Model Validation ◽  
Material Properties ◽  
Large Scale ◽  
Fluid Dynamic ◽  
Three Dimensional ◽  
Clay Content ◽  
Angle Of Repose ◽  
Model Parameters ◽  
Channel Curvature

Abstract. Here, we present validation tests of the fluid dynamic solver presented in von Boetticher et al. (2016), simulating both laboratory-scale and large-scale debris-flow experiments. The new solver combines a Coulomb viscoplastic rheological model with a Herschel–Bulkley model based on material properties and rheological characteristics of the analyzed debris flow. For the selected experiments in this study, all necessary material properties were known – the content of sand, clay (including its mineral composition) and gravel as well as the water content and the angle of repose of the gravel. Given these properties, two model parameters are sufficient for calibration, and a range of experiments with different material compositions can be reproduced by the model without recalibration. One calibration parameter, the Herschel–Bulkley exponent, was kept constant for all simulations. The model validation focuses on different case studies illustrating the sensitivity of debris flows to water and clay content, channel curvature, channel roughness and the angle of repose. We characterize the accuracy of the model using experimental observations of flow head positions, front velocities, run-out patterns and basal pressures.

Three-Dimensional Modeling and Model Validation of Circulating Fluidized Bed Combustion

2003 ◽  
Author(s):  
Kari Myo¨ha¨nen ◽  
Timo Hyppa¨nen ◽  
Jouni Miettinen ◽  
Riku Parkkonen
Keyword(s):  
Heat Flux ◽  
Fluidized Bed ◽  
Large Scale ◽  
Circulating Fluidized Bed ◽  
Combustion Process ◽  
Three Dimensional ◽  
Hot Water ◽  
Combustion Model ◽  
Process Conditions ◽  
Model Parameters

This paper presents a three-dimensional, steady state combustion model for a circulating fluidized bed (CFB) furnace and several calculation cases which have been used for the validation of the model. The model includes essential submodels to describe the complex combustion process in a circulating fluidized bed boiler. These include the hydrodynamics of the bed, devolatilization of fuel, combustion of char, combustion of hydrocarbons, carbon monoxide and hydrogen, calcination and sulfation, fragmentation and attrition of solids, heat transfer, overall mass balance of the furnace, and three-dimensional balance equations based on the finite volume method. The code was initially developed in 1989, and it has been updated and improved over the years as new methods and new information have become available. The model is used for increasing process knowledge and for studying such phenomena inside the furnace which are often difficult or impossible to study by direct measurements. The knowledge obtained is then applied to optimize boiler design and process performance in terms of efficiency, economy and environmental issues. Reliable experiments and measurements in commercial boilers are used for the validation of the model and for tuning the model parameters. For the validation of a three-dimensional model, extensive profile measurements of the various parts of the furnace are required. This paper presents validation studies for an 80 MWth hot water boiler burning bituminous coal and for a 235 MWe subcritical boiler burning lignite. The measurements with these units included profile measurements of heat flux, pressure, temperature and gas composition under different process conditions. The model was tuned according to the measurements and used for the prediction of the heat flux profile of a large scale supercritical CFB boiler.

scholarly journals Convection Modeling of Pure-steam Atmospheres

2021 ◽  
Vol 923 (1) ◽  
pp. L15
Author(s):  
Xianyu Tan ◽  
Maxence Lefèvre ◽  
Raymond T. Pierrehumbert
Keyword(s):  
Gravity Waves ◽  
Large Scale ◽  
Three Dimensional ◽  
Basic Structure ◽  
Model Parameters ◽  
Moist Convection ◽  
Wide Range ◽  
Convective Parameterization Scheme ◽  
Pure Steam ◽  
Convection Parameterization

Abstract Condensable species are crucial to shaping planetary climate. A wide range of planetary climate systems involve understanding nondilute condensable substances and their influence on climate dynamics. There has been progress on large-scale dynamical effects and on 1D convection parameterization, but resolved 3D moist convection remains unexplored in nondilute conditions, though it can have a profound impact on temperature/humidity profiles and cloud structure. In this work, we tackle this problem for pure-steam atmospheres using three-dimensional, high-resolution numerical simulations of convection in postrunaway atmospheres. We show that the atmosphere is composed of two characteristic regions, an upper condensing region dominated by gravity waves and a lower noncondensing region characterized by convective overturning cells. Velocities in the condensing region are much smaller than those in the lower, noncondensing region, and the horizontal temperature variation is small. Condensation in the thermal photosphere is largely driven by radiative cooling and tends to be statistically homogeneous. Some condensation also happens deeper, near the boundary of the condensing region, due to triggering by gravity waves and convective penetrations and exhibits random patchiness. This qualitative structure is insensitive to varying model parameters, but quantitative details may differ. Our results confirm theoretical expectations that atmospheres close to the pure-steam limit do not have organized deep convective plumes in the condensing region. The generalized convective parameterization scheme discussed in Ding & Pierrehumbert is appropriate for handling the basic structure of atmospheres near the pure-steam limit but cannot capture gravity waves and their mixing which appear in 3D convection-resolving models.

Neotectonics and landscape characterization in the Gawler Craton, South Australia - Insights through high-resolution remote sensing

2020 ◽  
Author(s):  
Cericia Martinez ◽  
Ulrich Kelka ◽  
Ignacio Gonzalez-Alvarez ◽  
Carmen Krapf
Keyword(s):  
High Resolution ◽  
Large Scale ◽  
Mineral Exploration ◽  
Gravity Data ◽  
South Australia ◽  
Magnetic Data ◽  
Surface Features ◽  
Mineral Potential ◽  
Landscape Characterization ◽  
Digital Elevation

<p>The Gawler Craton hosts significant economic mineralization within South Australia. Due to limited outcrops, deeply weathered profiles, and the absence of a clear variety of landscape surface features, mineral exploration is particularly challenging in this part of Australia. Here we present a workflow of data processing and interpretation to understand the neotectonics and landscape characterization of this region. We explore the potential to delineate surface lineaments and features from newly acquired high-resolution datasets. We aim to automatically identify landform domains based on the analysed data and investigate whether deep seated tectonic lineaments manifest in recognizable surface expressions.</p><p>The data we analyse in this study comprises digital elevation, radiometric, magnetic, and gravity data. We assume that elevation and radiometric data relate to surficial landscape features, whereas gravity and magnetic data represent subsurface basement features. Linking the analysis of both surface and subsurface datasets can potentially yield information on the neotectonic activity, and the association between landforms and basement structures as potential zones of fluid migration. We will show how processed digital elevation data can be used for automatic classification of different landform domains.</p><p>In order to assess mineral potential zones in the area, we compare the generated lineament data in terms of their geometric and topological properties to examine whether there is consistency in the subsurface and surface layers. We postulate that through a line density map, we may be able to quantify a potential relationship between lineaments that are representative in both the surface and subsurface, indicating potential faults or large-scale lineament trends that may link mineral systems in the basement with the landscape surface features. Areas that exhibit large numbers of surface and subsurface lineaments might be areas of enhanced mineral potential. This study contributes to enhance the efficiency of mineral exploration protocols in areas under cover.</p>

Three‐dimensional regularized focusing inversion of gravity gradient tensor component data

Geophysics ◽  
2004 ◽  
Vol 69 (4) ◽  
pp. 925-937 ◽  
Author(s):  
Michael S. Zhdanov ◽  
Robert Ellis ◽  
Souvik Mukherjee
Keyword(s):  
Local Density ◽  
Mineral Exploration ◽  
Gravity Data ◽  
Three Dimensional ◽  
Tensor Component ◽  
Airborne Gravity ◽  
Gravity Gradient ◽  
Gravity Method ◽  
Density Anomaly ◽  
And Inversion

We develop a new method for interpretation of tensor gravity field component data, based on regularized focusing inversion. The focusing inversion makes its possible to reconstruct a sharper image of the geological target than conventional maximum smoothness inversion. This new technique can be efficiently applied for the interpretation of gravity gradiometer data, which are sensitive to local density anomalies. The numerical modeling and inversion results show that the resolution of the gravity method can be improved significantly if we use tensor gravity data for interpretation. We also apply our method for inversion of the gradient gravity data collected by BHP Billiton over the Cannington Ag‐Pb‐Zn orebody in Queensland, Australia. The comparison with the drilling results demonstrates a remarkable correlation between the density anomaly reconstructed by the gravity gradient data and the true structure of the orebody. This result indicates that the emerging new geophysical technology of the airborne gravity gradient observations can improve significantly the practical effectiveness of the gravity method in mineral exploration.

scholarly journals Three-dimensional magnetotelluric model along seismic profile 2T: An improved view on crustal structure in central Slovakia (Western Carpathians)

2021 ◽  
Vol 72 (2) ◽  
Author(s):  
Ján Vozár ◽  
Vladimír Bezák ◽  
František Marko
Keyword(s):  
Crustal Structure ◽  
Large Scale ◽  
Gravity Data ◽  
Three Dimensional ◽  
Seismic Profile ◽  
Substantial Improvement ◽  
Western Carpathians ◽  
Geophysical Model ◽  
Outer Western Carpathians ◽  
Tectonic Style

We present the crustal-scale geophysical model based on the magnetotelluric method focused on 3-D model¬ling of the seismic 2T profile crossing the major Western Carpathian tectonic units in central Slovakia. The results of the 3-D modelling show substantial improvement in previous 2-D models of deep crustal structure in central Slovakia, mainly of the physically distinct tectonic segments and major geo-electrical regional structures like the zone of the Carpathian Conductivity Anomaly, which indicates the occurrence of the large-scale shear zone in the contact zone of the European platform and Inner Western Carpathians. High detail geo-electrical data in 3-D magnetotelluric (MT) cross section also allowed a better interpretation of other conductive anomalies. In the final integ-rated interpretation (combination of 3-D geo-electrical model, gravity data and seismic reflectors), it is shown that frontal part of the Inner Western Carpathians plate exhibits the transpressional tectonic style of the back-thrust Outer Western Carpathians (Flysch Belt) and Pieniny Klippen Belt units over the progressing Inner Western Carpathian thrust wedge. These back-thrusts form the southern branch of the accretionary structural fan – a large-scale transpressional flower structure typical mainly but not only for oblique con-vergent regimes. The southernmost segment of the profile with high whole-crust conductivity due to a higher heat flow caused by young volcanic activity indicates partial melting in the middle and lower crust.

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