scholarly journals Integrated Interpretation of Magnetic and ERT Data to Characterize a Landfill in the North-West of Cologne, Germany

2021 ◽  
Author(s):  
Ismael M. Ibraheem ◽  
Bülent Tezkan ◽  
Rainer Bergers
Keyword(s):  
Analytical Signal ◽  
Vertical Gradient ◽  
Magnetic Data ◽  
Inversion Method ◽  
Magnetic Survey ◽  
Electrode Arrays ◽  
L1 Norm ◽  
North West ◽  
The North ◽  
Migration Pathways

AbstractElectrical resistivity tomography (ERT) and ground magnetic surveys were applied to characterize an old uncontrolled landfill in a former exploited sand and gravel quarry in an area to the north-west of the city of Cologne, Germany. The total magnetic field and its vertical gradient were recorded using a proton precession magnetometer to cover an area of about 43,250 m2. The magnetic data were transferred to the frequency domain and then reduced to the north magnetic pole. The amplitude of the analytical signal was calculated to define the magnetic materials within and outside the landfill. Eight ERT profiles were constructed based on the results of the magnetic survey using different electrode arrays (Wenner, dipole–dipole, and Schlumberger). In order to increase both data coverage and sensitivity and to decrease uncertainty, a non-conventional mixed array was used. The subsurface resistivity distributions were imaged using the robust (L1-norm) inversion method. The resultant inverted subsurface true resistivity data were presented in the form of 2D cross sections and 3D fence diagram. These non-invasive geophysical tools helped us to portray the covering soil, the spatial limits of the landfill, and the depth of the waste body. We also successfully detected low resistivity zones at deeper depths than expected, which probably be associated with migration pathways of the leachate plumes. The findings of the present study provide valuable information for decision makers with regards to environmental monitoring and assessment.

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.

Interpretation of airborne magnetic survey of Gabel Um Tineidba area, south eastern desert, Egypt

2015 ◽  
Vol 12 (6) ◽  
pp. 563-576
Author(s):  
Tharwat H. Abdel Hafeez
Keyword(s):  
Analytical Signal ◽  
Eastern Desert ◽  
Structural Features ◽  
Geological Mapping ◽  
Magnetic Data ◽  
Magnetic Survey ◽  
Aeromagnetic Survey ◽  
Reasonable Proportion ◽  
The Cost ◽  
Airborne Magnetic

The study area is regionally covered by rock exposures ranging in age from the Precambrian to Quaternary. The aeromagnetic survey is a useful tool that help in geological mapping, providing information at a reasonable proportion of the cost of ground mapping. The reduced to the northern magnetic pole (RTP) map was separated into regional and residual magnetic component maps by the computed power spectrum of the magnetic data. The estimated mean depths of both regional and residual magnetic sources were found to be 2510 m and 383 m respectively. Also, two advanced techniques were used to analyze the depth magnetic data. These methods are analytical signal (AS) and source parameter imaging (SPI). The results of average depth estimates both methods (–950 m). These depth values were helped -to great extent- for define the direction of throw for the interpreted faults in the basement tectonic map. The statistical analysis shows that, most of the welldeveloped structural features are oriented mostly in the N-S, NNE-SSW, NW-SE and NNWSSE trending faults are considered the main trends affecting the distribution of the radioactive minerals.

Accuracy of wavelets, seismic inversion, and thin-bed resolution

2017 ◽  
Vol 5 (4) ◽  
pp. T523-T530
Author(s):  
Ehsan Zabihi Naeini ◽  
Mark Sams
Keyword(s):  
Seismic Data ◽  
Reservoir Characterization ◽  
Low Frequency ◽  
Seismic Inversion ◽  
Inversion Method ◽  
Frequency Content ◽  
Frequency Model ◽  
North West ◽  
The North ◽  
Well Data

Broadband reprocessed seismic data from the North West Shelf of Australia were inverted using wavelets estimated with a conventional approach. The inversion method applied was a facies-based inversion, in which the low-frequency model is a product of the inversion process itself, constrained by facies-dependent input trends, the resultant facies distribution, and the match to the seismic. The results identified the presence of a gas reservoir that had recently been confirmed through drilling. The reservoir is thin, with up to 15 ms of maximum thickness. The bandwidth of the seismic data is approximately 5–70 Hz, and the well data used to extract the wavelet used in the inversion are only 400 ms long. As such, there was little control on the lowest frequencies of the wavelet. Different wavelets were subsequently estimated using a variety of new techniques that attempt to address the limitations of short well-log segments and low-frequency seismic. The revised inversion showed greater gas-sand continuity and an extension of the reservoir at one flank. Noise-free synthetic examples indicate that thin-bed delineation can depend on the accuracy of the low-frequency content of the wavelets used for inversion. Underestimation of the low-frequency contents can result in missing thin beds, whereas underestimation of high frequencies can introduce false thin beds. Therefore, it is very important to correctly capture the full frequency content of the seismic data in terms of the amplitude and phase spectra of the estimated wavelets, which subsequently leads to a more accurate thin-bed reservoir characterization through inversion.

CARNARVON BASIN ARCHITECTURE AND STRUCTURE DEFINED BY THE INTEGRATION OF MINERAL AND PETROLEUM EXPLORATION TOOLS AND TECHNIQUES

2002 ◽  
Vol 42 (1) ◽  
pp. 287 ◽  
Author(s):  
L.L. Pryer ◽  
K.K. Romine ◽  
T.S. Loutit ◽  
R.G. Barnes
Keyword(s):  
Seismic Data ◽  
Structural Model ◽  
Mineral Exploration ◽  
Petroleum Exploration ◽  
Block Rotation ◽  
North West ◽  
The North ◽  
Northern Carnarvon Basin ◽  
Migration Pathways ◽  
Carnarvon Basin

The Barrow and Dampier Sub-basins of the Northern Carnarvon Basin developed by repeated reactivation of long-lived basement structures during Palaeozoic and Mesozoic tectonism. Inherited basement fabric specific to the terranes and mobile belts in the region comprise northwest, northeast, and north–south-trending Archaean and Proterozoic structures. Reactivation of these structures controlled the shape of the sub-basin depocentres and basement topography, and determined the orientation and style of structures in the sediments.The Lewis Trough is localised over a reactivated NEtrending former strike-slip zone, the North West Shelf (NWS) Megashear. The inboard Dampier Sub-basin reflects the influence of the fabric of the underlying Pilbara Craton. Proterozoic mobile belts underlie the Barrow Sub-basin where basement fabric is dominated by two structural trends, NE-trending Megashear structures offset sinistrally by NS-trending Pinjarra structures.The present-day geometry and basement topography of the basins is the result of accumulated deformation produced by three main tectonic phases. Regional NESW extension in the Devonian produced sinistral strikeslip on NE-trending Megashear structures. Large Devonian-Carboniferous pull-apart basins were introduced in the Barrow Sub-basin where Megashear structures stepped to the left and are responsible for the major structural differences between the Barrow and Dampier Sub-basins. Northwest extension in the Late Carboniferous to Early Permian marks the main extensional phase with extreme crustal attenuation. The majority of the Northern Carnarvon basin sediments were deposited during this extensional basin phase and the subsequent Triassic sag phase. Jurassic extension reactivated Permian faults during renewed NW extension. A change in extension direction occurred prior to Cretaceous sea floor spreading, manifest in basement block rotation concentrated in the Tithonian. This event changed the shape and size of basin compartments and altered fluid migration pathways.The currently mapped structural trends, compartment size and shape of the Barrow and Dampier Sub-basins of the Northern Carnarvon Basin reflect the “character” of the basement beneath and surrounding each of the subbasins.Basement character is defined by the composition, lithology, structure, grain, fabric, rheology and regolith of each basement terrane beneath or surrounding the target basins. Basement character can be discriminated and mapped with mineral exploration methods that use non-seismic data such as gravity, magnetics and bathymetry, and then calibrated with available seismic and well datasets. A range of remote sensing and geophysical datasets were systematically calibrated, integrated and interpreted starting at a scale of about 1:1.5 million (covering much of Western Australia) and progressing to scales of about 1:250,000 in the sub-basins. The interpretation produced a new view of the basement geology of the region and its influence on basin architecture and fill history. The bottom-up or basement-first interpretation process complements the more traditional top-down seismic and well-driven exploration methods, providing a consistent map-based regional structural model that constrains structural interpretation of seismic data.The combination of non-seismic and seismic data provides a powerful tool for mapping basement architecture (SEEBASE™: Structurally Enhanced view of Economic Basement); basement-involved faults (trap type and size); intra-sedimentary geology (igneous bodies, basement-detached faults, basin floor fans); primary fluid focussing and migration pathways and paleo-river drainage patterns, sediment composition and lithology.

SEISMIC DELINEATION OF STRUCTURE-CONTROLLED CARBONATE CEMENT AND POTENTIAL ECONOMIC IMPLICATIONS, ANGEL FIELD, NORTH WEST SHELF

1995 ◽  
Vol 35 (1) ◽  
pp. 280
Author(s):  
S. Ryan-Grigor ◽  
J.P. Schulz-Rojahn
Keyword(s):  
Seismic Data ◽  
High Amplitude ◽  
Fault System ◽  
3D Seismic ◽  
Economic Implications ◽  
Northern Margin ◽  
North West ◽  
The North ◽  
Migration Pathways ◽  
3D Seismic Data

Major carbonate-cemented zones occur in Late Jurassic Angel Formation sandstones of marine mass flow origin that contain large hydrocarbon reserves in the Angel Field, Dampier Sub-basin. Preliminary results suggest that poikilotopic dolomite cement is dominant. The carbonate-cemented zones are identifiable from wireline log response and 3D seismic data, and occur in discrete intervals with a cumulative thickness of approximately 165m at Angel-2. These intervals produce a zone of high amplitude reflections of about 100 ms two-way time. Field-wide seismic mapping indicates that these carbonate-cemented zones sharply abut the northern margin of a major east-west trending strike-slip fault system that traverses this field. The carbonate-cemented zones extend in a wedge-like shape towards the northeast and concentrate along the crest of the main structural trend.The results underscore the importance of 3D seismic data for a better estimation of reservoir risk and reserves in variably carbonate-cemented sandstones.The carbonate-cemented zones may represent a 'plume' related to migration of petroleum and/or carbon dioxide. Therefore delineation of major carbonate-cemented zones using seismic data may aid in the identification of petroleum migration pathways and pools in the North West Shelf. Alternatively, carbonate cements dissolved south of the major fault zone and possibly in downdip locations in which case dissolution pores may exist in these areas. Further research is required to evaluate these hypotheses.

scholarly journals Estimation of path attenuation and site characteristics in the north-west Himalaya and its adjoining area using generalized inversion method

2018 ◽  
Author(s):  
Harinarayan Nelliparambil Hareeshkumar ◽  
Abhishek Kumar
Keyword(s):  
Site Amplification ◽  
Inversion Method ◽  
Predominant Frequency ◽  
S Wave ◽  
North West ◽  
Hypocentral Distance ◽  
The North ◽  
Generalized Inversion ◽  
Site Characteristics ◽  
West Himalaya

Abstract. Present work focuses on the determination of path attenuation as well as site characteristics of PESMOS managed recording stations, located in the north-west Himalaya and its adjoining region, using two-step generalized inversion technique. In the first step of inversion, non-parametric attenuation curves are developed. Presence of a kink is observed at around 105 km hypocentral distance while correlating the path attenuation with the hypocentral distance indicating the presence of Moho discontinuity in the region. Further, Qs = 105 f0.94 as S wave quality factor within 105 km, is obtained indicating that the region is possibly heterogeneous as well as seismically active. In the second step of inversion, site amplification curves are developed separately from the attenuation corrected data for horizontal and vertical components of the accelerogram. Further, site amplification spectra is computed as the ratio of the obtained horizontal and vertical components to determine the amplification function and predominant frequency for each of the PESMOS managed recording stations, exist within the study area. The predominant frequency based on generalized inversion method and based on horizontal to vertical spectral ratio of S wave portion of the accelerogram matches well. Maps showing spatial distribution of predominant frequencies and amplification functions across the study region are also developed based on the present work.

scholarly journals COMPARISON OF THE GEOELECTRIC SIGNATURE WITH DIFFERENT ELECTRODE ARRAYS AT THE JOCKEY CLUB LANDFILL OF BRASÍLIA, DF, BRAZIL

2020 ◽  
Vol 38 (1) ◽  
pp. 41
Author(s):  
Victor José Cavalcanti Bezerra Guedes ◽  
Victória Basileu de Oliveira Lima ◽  
Welitom Rodrigues Borges ◽  
Luciano Soares da Cunha
Keyword(s):  
Electrical Resistivity ◽  
Electrical Resistivity Tomography ◽  
Inversion Method ◽  
Electrode Arrays ◽  
L1 Norm ◽  
Resistivity Tomography ◽  
L2 Norm ◽  
Data Resolution ◽  
Multichannel Data ◽  
Jockey Club

ABSTRACT. The influence of array configurations on the resolution of subsurface electrical resistivity tomography (ERT) imaging is one of the most discussed factors when it comes to resistivity data quality. Despite the flexibility of multichannel data acquisition systems nowadays, there is still a tendency to perform field observations with traditional arrays, mainly because they are already well understood configurations. The present work discusses a comparison between the results obtained with four electrode arrays (dipole dipole, pole-dipole, Wenner-Schlumberger and Wenner) regarding the data resolution and the ability to identify the bedrock over the buried waste in the former Jockey Club landfill of Brasília, an important information to delimit the geometry of the mass of waste. Four electroresistivity lines were acquired with different electrode arrays, using the ERT technique, and models were calculated using the Res2DInv software, by the robust inversion method (L1-norm) and smooth-constrained least squares inversion (L2-norm). All arrangements produced models that presented the mass of waste with low resistivity, indicating strong influence of leachate. The best agreement with borehole information regarding the bedrock level was achieved with the dipole-dipole array. The L1-norm inversion provided more stable and smoothed models than the results obtained with the L2-norm method, also presenting smaller differences between the calculated and observed apparent resistivity.KEYWORDS: Electrical Resistivity Tomography, electrode arrays, waste disposal. COMPARAÇÃO DA ASSINATURA GEOELÉTRICA COM DIFERENTES ARRANJOS ELETRÓDICOS NO ATERRO JOCKEY CLUBE DE BRASÍLIA, DF, BRASILRESUMO. A influência do arranjo eletródico na resolução de imageamento por tomografia de resistividade elétrica (TRE) da subsuperfície é um dos fatores mais discutidos quando se trata de qualidade de dados de resistividade. Apesar da flexibilidade dos sistemas multicanais de aquisição de dados, ainda há uma tendência em realizar observações em campo com arranjos tradicionais de eletrodos, devido a serem configurações já bem compreendidas. No presente trabalho, é discutida uma comparação entre os resultados obtidos a partir de quatro arranjos de eletrodos (dipolo-dipolo, polo-dipolo, Wenner-Schlumberger e Wenner) quanto a resolução dos dados e quanto a capacidade de identificar o embasamento rochoso sobre o maciço de resíduos no antigo aterro controlado do Jockey Clube de Brasília, uma importante informação para delimitar a geometria do maciço de resíduos. Foram adquiridas quatro linhas de eletrorresistividade com diferentes arranjos eletródicos, com a técnica TRE, e foram calculados modelos no software Res2DInv pelo método de inversão robusta (norma-L1) e de inversão de mínimos quadrados com restrição de suavidade (norma-L2). Todos os arranjos produziram modelos que apresentaram o maciço de resíduos com baixa resistividade, indicando forte influência de chorume. As melhores concordâncias com as informações de furos de sondagem foram alcançadas com o arranjo dipolo-dipolo. A inversão norma-L1 forneceu modelos mais estáveis e suavizados do que os resultados obtidos com a norma-L2, também apresentando diferenças menores entre a resistividade aparente calculada e medida.PALAVRAS-CHAVE: Tomografia de Resistividade Elétrica, arranjos eletródicos, disposição de resíduos.

Excavations at Verulamium, 1960: Sixth Interim Report

1961 ◽  
Vol 41 (1-2) ◽  
pp. 72-85 ◽  
Author(s):  
S. S. Frere
Keyword(s):  
Small Area ◽  
Fifth Century ◽  
Main Task ◽  
Magnetic Survey ◽  
West Side ◽  
North West ◽  
The North ◽  
South West ◽  
Complete Work ◽  
Pipe Line

The sixth season at Verulamium lasted a period of five weeks from 20th July to 24th August 1960. As the last full season of the current programme, it was designed to test one or two specific questions and to complete work already begun. Trenches were cut in insulae XIX and XXVIII in an attempt to define the south-east and south-west sides respectively of the suspected Claudian fort, but met with no success. In insula XIV a small area still outstanding was excavated down to the level of the Antonine fire: in insula XXI further work was done on building 2, to complete the plan and to salvage some painted wall plaster still remaining. In insula XXVII the stoke-hole, added perhaps as late as the early fifth century to building 2, room 15, was examined and trenches were cut to trace the further course of the fifth-century pipe-line. The main task for 1960, however, was to test the results of the proton-magnetometer survey carried out in 1959, by cutting sections across the line thus suggested for the ‘1955 Ditch’. This was done at two points, the first in insula VIII and the second just south-west of insula V, and the existence of the earthwork on the course predicted was confirmed. Later in the autumn the north-west side of the enclosure was defined by a further magnetic survey by Dr. M. J. Aitken.

scholarly journals Evaluation of mafic dyke swarm continuity under the Joaquina dune field with ground magnetic survey

2017 ◽  
Vol 47 (2) ◽  
pp. 237-247 ◽  
Author(s):  
George Caminha-Maciel ◽  
Marcia Ernesto ◽  
Welitom R. Borges ◽  
Junior Bresolin ◽  
Reginaldo Lemos
Keyword(s):  
Vertical Gradient ◽  
Crystalline Basement ◽  
Dyke Swarm ◽  
Magnetic Survey ◽  
The North ◽  
Magnetic Signature ◽  
Mafic Dyke Swarm ◽  
Gradient Measurements ◽  
Ground Magnetic ◽  
North And South

ABSTRACT: A ground magnetic survey in a Central-East area of the Santa Catarina Island tested the continuity of the Cretaceous mafic dykes beneath the aeolic sediments of the Joaquina plain. Vertical gradient measurements taken in 1880 stations did not detect any magnetic anomaly related to subsurface dykes. Four magnetic profiles located to the north and south of the main area showed the magnetic signature of various dykes some of them already mapped (north profiles), but also some in subsurface (south profiles). These results suggest that the dykes probably were shallow and truncated, and were already eroded along with the crystalline basement.

scholarly journals A New Method for the Collection of Marine Geomagnetic Information: Survey Application in the Colombian Caribbean

2020 ◽  
Vol 9 (1) ◽  
pp. 10
Author(s):  
Karem Oviedo Prada ◽  
Bismarck Jigena Antelo ◽  
Nathalia Otálora Murillo ◽  
Jeanette Romero Cózar ◽  
Francisco Contreras-de-Villar ◽  
...  
Keyword(s):  
Magnetic Data ◽  
Data Repository ◽  
Time Interval ◽  
Side Scan Sonar ◽  
North West ◽  
The North ◽  
Geomagnetic Data ◽  
Long Time ◽  
Advance Research ◽  
Maritime Territory

In recent years, the Oceanographic and Hydrographic Research Center (part of the General Maritime Directorate of Colombia (DIMAR) has made important efforts to advance research in the field of marine geophysics, in particular, the techniques of geomagnetism, sub-bottom profiling, and side-scan sonar, the first being the most developed at the present time. A method is presented for the acquisition of geomagnetic data in marine environments, as used by DIMAR in the Colombian maritime territory. The development of the geomagnetic method not only offers the opportunity to advance basic scientific knowledge, but it is also of great importance in support of national sovereignty issues. Among other applications, the most representative uses of the geomagnetic method are the location of pipelines and metal plates, detection of buried ordnance, identification of sites of archaeological interest, and the identification and characterization of geological structures. As a result of testing the method, a grid of geomagnetic data was surveyed in an area close to the Island of San Andrés in the north-west of the Colombian maritime territory. The survey was prepared with a regional geometric arrangement, the result of which was compared with survey data obtained from the National Oceanic and Atmospheric Administration (NOAA) magnetic data repository and carried out in the same study area. Despite the long time interval between the two surveys, almost 50 years, no significant differences were observed in terms of the analyzed variables. Finally, results show negligible differences between the magnetic data obtained for the years 1970 and 2018 for all the variables measured, such as the inclination, declination, and total magnetic field. These differences may be attributable to a geological component or also to the acquisition and processing methods used in the 1970s.

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