Magnetic and Geo-electrical Geophysical Techniques for Subsurface Delineation and Groundwater Assessment in Ras Matarma, Sinai

2020 ◽  
Vol 25 (3) ◽  
pp. 425-431
Author(s):  
Noha A. Hassan ◽  
Mohamed H. Khalil ◽  
Mahmoud Ghaleb
Keyword(s):  
Magnetic Data ◽  
Magnetic Survey ◽  
Qualitative And Quantitative ◽  
Resistivity Survey ◽  
True Resistivity ◽  
Groundwater Assessment ◽  
Gis And Rs ◽  
Resistivity Inversion ◽  
Ground Magnetic ◽  
Shallow And Deep Structures

Groundwater constitutes the main source of the freshwater in Ras-Matarma, Sinai, which necessitates optimized management of it. In this context, geophysical ground magnetic, Schlumberger resistivity inversion, remote sensing (RS), geographic information system (GIS), and pumping tests were conducted. The magnetic survey comprised 56 profiles, whereas, Schlumberger resistivity survey were 27 VES. GIS and RS were implemented for watershed analyses in the area. Interpretation of the magnetic data separated significantly the shallow and deep structures with depths ranged from 300 to 1400 m. Qualitative and quantitative modelling of the inverted resistivity data demarcated effectively the fresh aquifer with true resistivity and thickness ranged from 22 to 210 ohm.m and 2 to 80 m, respectively. GIS aggregated all the aforementioned results along with electric and hydraulic parameters of the fresh aquifer.

Next Generation High-Definition Geomagnetic Model for Wellbore Positioning, Incorporating New Crustal Magnetic Data

2021 ◽  
Author(s):  
Manoj Nair ◽  
Arnaud Chulliat ◽  
Adam Woods ◽  
Patrick Alken ◽  
Brian Meyer ◽  
...  
Keyword(s):  
Magnetic Field ◽  
High Resolution ◽  
Error Model ◽  
Magnetic Data ◽  
Magnetic Observatory ◽  
Magnetic Survey ◽  
High Definition ◽  
The Core ◽  
Ground Magnetic ◽  
The Magnetic Field

Abstract Magnetic wellbore positioning depends on an accurate representation of the Earth's magnetic field,where the borehole azimuth is inferred by comparing the magnetic field measured-whiledrilling (MWD) with a geomagnetic reference model. Therefore, model accuracy improvements reduce the position uncertainties. An improved high-resolution model describing the core, crustal and external components of the magnetic field is presented, and it is validated with anindependent set of measurements. Additionally, we benchmark it against other high-resolution geomagnetic models. The crustal part of the improved high-definition model is based on NOAA/NCEI's latest magnetic survey compilation "EMAG2v3" which includes over 50 millionnew observations in several parts of the world, including the Gulf of Mexico and Antarctica, and does not rely on any prior information from sea-floor geology, unlike earlier versions. The core field part of the model covers years 1900 through 2020 andis inferred from polar-orbiting satellite data as well as ground magnetic observatory data. The external field part is modelled to degree and order 1 for years 2000 through 2020. The new model has internal coefficients to spherical harmonic degree and order 790, resolving magnetic anomalies to approximately 51 km wavelength at the equator. In order to quantitatively assess its accuracy, the model was compared with independent shipborne, airborne and ground magnetic measurements. We find that the newmodel has comparable or smaller errors than the other models benchmarkedagainst it over the regions of comparisons. Additionally, we compare theimproved model against magnetic datacollected from MWD; the residual error lies well within the accepted industry error model, which may lead tofuture error model improvements.

Airborne geophysical surveys in Greenland in 1998

1999 ◽  
pp. 34-38 ◽  
Author(s):  
Thorkild M. Rasmussen ◽  
Leif Thorning
Keyword(s):  
High Resolution ◽  
Geophysical Data ◽  
Digital Data ◽  
Geological Survey ◽  
Magnetic Data ◽  
Magnetic Survey ◽  
Original Series ◽  
Geophysical Surveys ◽  
The Government

NOTE: This article was published in a former series of GEUS Bulletin. Please use the original series name when citing this article, for example: Rasmussen, T. M., & Thorning, L. (1999). Airborne geophysical surveys in Greenland in 1998. Geology of Greenland Survey Bulletin, 183, 34-38. https://doi.org/10.34194/ggub.v183.5202 _______________ Airborne geophysical surveying in Greenland during 1998 consisted of a magnetic project referred to as ‘Aeromag 1998’ and a combined electromagnetic and magnetic project referred to as ‘AEM Greenland 1998’. The Government of Greenland financed both with administration managed by the Geological Survey of Denmark and Greenland (GEUS). With the completion of the two projects, approximately 305 000 line km of regional high-resolution magnetic data and approximately 75 000 line km of detailed multiparameter data (electromagnetic, magnetic and partly radiometric) are now available from government financed projects. Figure 1 shows the location of the surveyed areas with highresolution geophysical data together with the area selected for a magnetic survey in 1999. Completion of the two projects was marked by the release of data on 1 March, 1999. The data are included in the geoscientific databases at the Survey for public use; digital data and maps may be purchased from the Survey.

scholarly journals Compact Quantum Magnetometer System on an Agile Underwater Glider

Sensors ◽  
2021 ◽  
Vol 21 (4) ◽  
pp. 1092
Author(s):  
Brian R. Page ◽  
Reeve Lambert ◽  
Nina Mahmoudian ◽  
David H. Newby ◽  
Elizabeth L. Foley ◽  
...  
Keyword(s):  
Test Procedure ◽  
Reduction Process ◽  
Ground Truth ◽  
Sensor Technology ◽  
Magnetic Data ◽  
Magnetic Survey ◽  
Underwater Glider ◽  
Combined System ◽  
Extended Operation ◽  
Quantum Magnetometer

This paper presents results from the integration of a compact quantum magnetometer system and an agile underwater glider for magnetic survey. A highly maneuverable underwater glider, ROUGHIE, was customized to carry an increased payload and reduce the vehicle’s magnetic signature. A sensor suite composed of a vector and scalar magnetometer was mounted in an external boom at the rear of the vehicle. The combined system was deployed in a constrained pool environment to detect seeded magnetic targets and create a magnetic map of the test area. Presented is a systematic magnetic disturbance reduction process, test procedure for anomaly mapping, and results from constrained operation featuring underwater motion capture system for ground truth localization. Validation in the noisy and constrained pool environment creates a trajectory towards affordable littoral magnetic anomaly mapping infrastructure. Such a marine sensor technology will be capable of extended operation in challenging areas while providing high-resolution, timely magnetic data to operators for automated detection and classification of marine objects.

Interpretation of ground magnetic data in Suyoc, Mankayan Mineral District, Philippines

2021 ◽  
Author(s):  
Creszyl Joy J. Arellano ◽  
Leo T. Armada ◽  
Carla B. Dimalanta ◽  
Karlo L. Queaño ◽  
Eric S. Andal ◽  
...  
Keyword(s):  
Magnetic Data ◽  
Ground Magnetic ◽  
Mineral District

Optical filtering of airborne and ground magnetic data

1976 ◽  
Vol 114 (4) ◽  
pp. 663-683 ◽  
Author(s):  
M. K. Seguin ◽  
H. H. Arsenault
Keyword(s):  
Magnetic Data ◽  
Optical Filtering ◽  
Ground Magnetic

Ground magnetic survey for the investigation of magnetic minerals at Iboro Village, Abeokuta, south-western Nigeria

2021 ◽  
Vol 20 (2) ◽  
pp. 99-106
Author(s):  
O.I. Popoola ◽  
O.A. Adenuga ◽  
E.O. Joshua
Keyword(s):  
Magnetic Anomalies ◽  
Geological Structure ◽  
Magnetic Survey ◽  
Magnetic Minerals ◽  
Contour Maps ◽  
Ogun State ◽  
Geological Map ◽  
Regional Gradient ◽  
Ground Magnetic ◽  
Iron Ore Deposit

The geological map of the old western region of Nigeria indicates the presence of iron ore deposit at Iboro village Ogun state (7.9983o - 7.99933o N, 3.5790o - 3.5890o E). Hence a ground magnetic survey was carried out at a location at Iboro village so as to delineate the subsurface magnetic anomalies and to know whether the anomalies favour accumulation of magnetic minerals. The survey was carried out using high resolution proton precession magnetometer model G-856X. Eight traverses were run at 5m separations and earth magnetic intensity values were measured at 10m intervals along each traverse; the acquired data were corrected for drift. The residual anomalies obtained by removal of regional gradient from observed data using trend analysis were presented as profiles and maps. The treated data were qualitatively and quantitatively interpreted and the results gave values for the total ground magnetic anomalies that varied between a minimum and maximum peak values of about -33.0 and 30.6nT respectively. Depth to the basement rock was estimated using Peter’s half slope method which gave a maximum depth of about 13m. The contour maps and the total relative graphs present the subsurface picture of the geological structure that is assumed to harbour the metallic minerals through the action of the field towards the concentration of anomalies. It was suspected that the overburden was relatively thin in the study area and the minerals were at a shallow depth.

Resolving Optimum Magnetic Signatures for Drill-Hole Targeting in Gold Exploration – A Case Study for Mbudzane in Gwanda, Zimbabwe

2013 ◽  
Vol 3 (1) ◽  
pp. 9-29
Author(s):  
Dumisani John Hlatywayo ◽  
Emmanuel Sakala
Keyword(s):  
Drill Hole ◽  
Magnetic Survey ◽  
Gold Exploration ◽  
Rock Formations ◽  
Induced Polarisation ◽  
Line Spacing ◽  
Magnetic Signatures ◽  
Ground Magnetic ◽  
Tilt Derivative ◽  
Resistivity Image

Optimum magnetic signatures for drill-hole targeting in gold exploration in Mbudzane were resolved from induced polarisation-resistivity and magnetic anomalies. Total magnetic field and a gold-in-soil map showed the area is magnetically quiet with high anomalous values along old gold workings. Induced polarisation was carried out along a grid for lines of 500m length, 50m separation and a baseline oriented at 330˚. The survey comprised a gradient array and three real sections. The magnetic survey was conducted over the same grid as the induced polarisation. Stations were set at 5m intervals for a line spacing of 50m. The results show intense anomalies that suggest different degrees of magnetic alteration and a set of conjugate lineaments and faults that possibly control the mineralisation in Mbudzane. The tilt derivative of the reduced-to-pole image resolves the separation between anomalies, giving information on the faulting. High chargeability is confined to the sheared and silicified mafic schist. The gradient resistivity image revealed contact between rock formations. Real section IP shows coincident low chargeability – low resistivity anomalies close to the surface. Chargeability intensity increases with depth, suggesting incipient development of disseminated sulphide replacement zones. A strong correlation between ground magnetic inferred contacts and apparent resistivity-chargeability anomalies forms the basis for suggesting a new drill-hole targeting. They dictate both the depth and angle at which drilling should be carried out. These results should be applicable to any region where drill-hole targeting in gold exploration may be required.

scholarly journals A Novel Noise Reduction Method of UAV Magnetic Survey Data Based on CEEMDAN, Permutation Entropy, Correlation Coefficient and Wavelet Threshold Denoising

Entropy ◽  
2021 ◽  
Vol 23 (10) ◽  
pp. 1309
Author(s):  
Yaoxin Zheng ◽  
Shiyan Li ◽  
Kang Xing ◽  
Xiaojuan Zhang
Keyword(s):  
Noise Reduction ◽  
Correlation Coefficient ◽  
Field Experiments ◽  
Reduction Method ◽  
Magnetic Data ◽  
Permutation Entropy ◽  
Magnetic Survey ◽  
Intrinsic Mode Functions ◽  
Real Signal ◽  
The Real

Despite the increased attention that has been given to the unmanned aerial vehicle (UAV)-based magnetic survey systems in the past decade, the processing of UAV magnetic data is still a tough task. In this paper, we propose a novel noise reduction method of UAV magnetic data based on complete ensemble empirical mode decomposition with adaptive noise (CEEMDAN), permutation entropy (PE), correlation coefficient and wavelet threshold denoising. The original signal is first decomposed into several intrinsic mode functions (IMFs) by CEEMDAN, and the PE of each IMF is calculated. Second, IMFs are divided into four categories according to the quartiles of PE, namely, noise IMFs, noise-dominant IMFs, signal-dominant IMFs, and signal IMFs. Then the noise IMFs are removed, and correlation coefficients are used to identify the real signal-dominant IMFs. Finally, the wavelet threshold denoising is applied to the real signal-dominant IMFs, the denoised signal can be obtained by combining the signal IMFs and the denoised IMFs. Both synthetic and field experiments are conducted to verify the effectiveness of the proposed method. The results show that the proposed method can eliminate the interference to a great extent, which lays a foundation for the further interpretation of UAV magnetic data.

scholarly journals Performance of Two Different Flight Configurations for Drone-Borne Magnetic Data

Sensors ◽  
2021 ◽  
Vol 21 (17) ◽  
pp. 5736
Author(s):  
Filippo Accomando ◽  
Andrea Vitale ◽  
Antonello Bonfante ◽  
Maurizio Buonanno ◽  
Giovanni Florio
Keyword(s):  
Electromagnetic Interference ◽  
Source Parameters ◽  
Spectral Characteristics ◽  
Magnetic Data ◽  
Prototype System ◽  
Control Dataset ◽  
Periodic Data ◽  
Ground Magnetic ◽  
The Stability ◽  
Careful Processing

The compensation of magnetic and electromagnetic interference generated by drones is one of the main problems related to drone-borne magnetometry. The simplest solution is to suspend the magnetometer at a certain distance from the drone. However, this choice may compromise the flight stability or introduce periodic data variations generated by the oscillations of the magnetometer. We studied this problem by conducting two drone-borne magnetic surveys using a prototype system based on a cesium-vapor magnetometer with a 1000 Hz sampling frequency. First, the magnetometer was fixed to the drone landing-sled (at 0.5 m from the rotors), and then it was suspended 3 m below the drone. These two configurations illustrate endmembers of the possible solutions, favoring the stability of the system during flight or the minimization of the mobile platform noise. Drone-generated noise was filtered according to a CWT analysis, and both the spectral characteristics and the modelled source parameters resulted analogously to that of a ground magnetic dataset in the same area, which were here taken as a control dataset. This study demonstrates that careful processing can return high quality drone-borne data using both flight configurations. The optimal flight solution can be chosen depending on the survey target and flight conditions.

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