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Vertical Electrical Sounding
Vertical electrical sounding (VES) is a geophysical method for investigation of a geological medium. The method is based on the estimation of the electrical conductivity or resistivity of the medium. The estimation is performed based on the measurement of voltage of electrical field induced by the distant grounded electrodes (current electrodes). Measurements Figures 1–4 show the possible configuration of the measurement setup. The electrodes ''A'' and ''B'' are current electrodes which are connected to a current source; ''N'' and ''M'' are potential electrodes which are used for the voltage measurements. As source, the direct current or low frequency alternating current is used. The interpretation of the measurements can be performed based on the apparent resistivity values. The depth of investigation depends on the distance between the current electrodes. In order to obtain the apparent resistivity as the function of depth, the measurements for each position are performed w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electrical Conductivity
Electrical resistivity (also called specific electrical resistance or volume resistivity) is a fundamental property of a material that measures how strongly it resists electric current. A low resistivity indicates a material that readily allows electric current. Resistivity is commonly represented by the Greek letter (rho). The SI unit of electrical resistivity is the ohm-meter (Ω⋅m). For example, if a solid cube of material has sheet contacts on two opposite faces, and the resistance between these contacts is , then the resistivity of the material is . Electrical conductivity or specific conductance is the reciprocal of electrical resistivity. It represents a material's ability to conduct electric current. It is commonly signified by the Greek letter ( sigma), but ( kappa) (especially in electrical engineering) and ( gamma) are sometimes used. The SI unit of electrical conductivity is siemens per metre (S/m). Resistivity and conductivity are inte ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electrode
An electrode is an electrical conductor used to make contact with a nonmetallic part of a circuit (e.g. a semiconductor, an electrolyte, a vacuum or air). Electrodes are essential parts of batteries that can consist of a variety of materials depending on the type of battery. The electrophore, invented by Johan Wilcke, was an early version of an electrode used to study static electricity. Anode and cathode in electrochemical cells Electrodes are an essential part of any battery. The first electrochemical battery made was devised by Alessandro Volta and was aptly named the Voltaic cell. This battery consisted of a stack of copper and zinc electrodes separated by brine-soaked paper disks. Due to fluctuation in the voltage provided by the voltaic cell it wasn't very practical. The first practical battery was invented in 1839 and named the Daniell cell after John Frederic Daniell. Still making use of the zinc–copper electrode combination. Since then many more batteries have be ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wenner
Wenner is a surname. Notable people with the surname include: *Axel Wenner-Gren (1881–1961), Swedish entrepreneur, one of the richest men in the world during the 1930s *Christopher Wenner (born 1954), British journalist and former British television presenter * François Wenner (1889–1964), was governor of Lusambo Province in the Belgian Congo from 1940 to 1944 * Jann Wenner (born 1946), the co-founder and publisher of the music and politics biweekly ''Rolling Stone'' *Kurt Wenner, artist best known for his realistic street painting and chalk murals using a projection called anamorphosis * Max Wenner (1887–1937), landowner and "man of mystery," disappeared from a plane over Belgium in 1937; great-uncle of Christopher Wenner mentioned above * Rosemarie Wenner (born 1955), the current Presiding Bishop of the United Methodist Church in Germany See also * Corliss v. Wenner, 34 P.3d 1100 (Idaho 2001), case decided by the Court of Appeals of Idaho * Wenner-Gren Center, tower and b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Schlumberger
Schlumberger Limited (), doing business as SLB, is an oilfield services company. Schlumberger has four principal executive offices located in Paris, Houston, London, and The Hague. Schlumberger is the world's largest offshore drilling company. It is the biggest offshore drilling contractor (in terms of revenue) in the world. Schlumberger is incorporated in Willemstad, Curaçao as Schlumberger N.V. and trades on the New York Stock Exchange, Euronext Paris, the London Stock Exchange and SIX Swiss Exchange. Schlumberger is a Fortune Global 500 company, ranked 287 in 2016, and also listed in Forbes Global 2000, ranked 349 in 2022. History Schlumberger was founded in 1926 in Paris as the Electric Prospecting Company (french: Société de prospection électrique) by two brothers Conrad and Marcel Schlumberger from Alsace. Schlumberger supplies the petroleum industry with services such as seismic data processing, formation evaluation, well testing and directional drilling ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electrode Array
An electrode array is a configuration of electrodes used for measuring either an electric current or voltage. Some electrode arrays can operate in a bidirectional fashion, in that they can also be used to provide a stimulating pattern of electric current or voltage. Common arrays include: *Schlumberger (Wenner) *Wenner alpha *Wenner beta *Wenner gamma *Pole-pole *Dipole-dipole *Pole-dipole *Equatorial dipole-dipole Resistivity Resistivity measurement of bulk materials is a frequent application of electrode arrays. The figure shows a Wenner array, one of the possible ways of achieving this. Injecting the current through electrodes separate from those being used for measurement of potential has the advantage of eliminating any inaccuracies caused by the injecting circuit resistance, particularly the contact resistance between the probe and the surface, which can be high. Assuming the material is homogenous, the resistivity in the Wenner array is given by: :\rho=2 \pi a \frac w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electrical Resistivity Tomography
Electrical resistivity tomography (ERT) or electrical resistivity imaging (ERI) is a geophysical technique for imaging sub-surface structures from electrical resistivity measurements made at the surface, or by electrodes in one or more boreholes. If the electrodes are suspended in the boreholes, deeper sections can be investigated. It is closely related to the medical imaging technique electrical impedance tomography (EIT), and mathematically is the same inverse problem. In contrast to medical EIT, however, ERT is essentially a direct current method. A related geophysical method, induced polarization (or spectral induced polarization), measures the transient response and aims to determine the subsurface chargeability properties. Electrical resistivity measurements can be used for identification and quantification of depth of groundwater, detection of clays, and measurement of groundwater conductivity. History The technique evolved from techniques of electrical prospecting th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Magnetotellurics
Magnetotellurics (MT) is an electromagnetic geophysical method for inferring the earth's subsurface electrical conductivity from measurements of natural geomagnetic and geoelectric field variation at the Earth's surface. Investigation depth ranges from 300 m below ground by recording higher frequencies down to 10,000 m or deeper with long-period soundings. Proposed in Japan in the 1940s, and France and the USSR during the early 1950s, MT is now an international academic discipline and is used in exploration surveys around the world. Commercial uses include hydrocarbon (oil and gas) exploration, geothermal exploration, carbon sequestration, mining exploration, as well as hydrocarbon and groundwater monitoring. Research applications include experimentation to further develop the MT technique, long-period deep crustal exploration, deep mantle probing, sub-glacial water flow mapping, and earthquake precursor research. History The magnetotelluric technique was introduc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Seismo-electromagnetics
Seismo-electromagnetics are various electro-magnetic phenomena believed to be generated by tectonic forces acting on the earth's crust, and possibly associated with seismic activity such as earthquakes and volcanoes. Study of these has been prompted by the prospect they might be generated by the increased stress leading up to an earthquake, and might thereby provide a basis for short-term earthquake prediction. However, despite many studies, no form of seismo-electromagnetics has been shown to be effective for earthquake prediction. A key problem is that earthquakes themselves produce relatively weak electromagnetic phenomena, and the effects from any precursory phenomena are likely to be too weak to measure. Close monitoring of the Parkfield earthquake revealed no significant pre-seismic electromagnetic effects. However, some researchers remain optimistic, and searches for seismo-electromagnetic earthquake precursors continue. VAN method The VAN method – named after P. Varot ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Telluric Current
A telluric current (from Latin ''tellūs'', "earth"), or Earth current, This has a detailed history of observations as understood at the time. is an electric current which moves underground or through the sea. Telluric currents result from both natural causes and human activity, and the discrete currents interact in a complex pattern. The currents are extremely low frequency and travel over large areas at or near the surface of the Earth. Description Telluric currents are phenomena observed in the Earth's crust and mantle. In September 1862, an experiment to specifically address Earth currents was carried out in the Munich Alps (Lamont, 1862). Including minor processes, there are at least 32 different mechanisms which cause telluric currents. The strongest are primarily geomagnetically induced currents, which are induced by changes in the outer part of the Earth's magnetic field, which are usually caused by interactions between the solar wind and the magnetosphere or solar radiat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geophysical Imaging
Geophysical imaging (also known as geophysical tomography) is a minimally destructive geophysical technique that investigates the subsurface of a terrestrial planet. Geophysical imaging is a noninvasive imaging technique with a high parametrical and spatio-temporal resolution. Geophysical imaging has evolved over the last 30 years due to advances in computing power and speed. It can be used to model a surface or object understudy in 2D or 3D as well as monitor changes. There are many applications of geophysical imaging some of which include imaging the lithosphere and imaging glaciers. Many different techniques exist to perform geophysical imaging including seismic methods, electrical resistivity tomography, ground-penetrating radar, etc. Types of geophysical imaging: *Electrical resistivity tomography *Ground-penetrating radar * Induced polarization *Seismic tomography and Reflection seismology *Magnetotellurics Applications Imaging the Lithosphere Some geophysical imagi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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