Download or read book On the Physics of Galvanic Source Electromagnetic Geophysical Methods for Terrestrial and Marine Exploration written by Evan S. Um and published by . This book was released on 2005 with total page 474 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book ON THE PHYSICS OF GALVANIC SOURCE ELECTROMAGNETIC GEOPHYSICAL METHODS FOR TERRESTRIAL AND MARINE EXPLORATION written by and published by . This book was released on 2007 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A numerical study was conducted to investigate the governing physics of galvanic source electromagnetic (EM) methods for terrestrial and marine exploration scenarios. The terrestrial exploration scenario involves the grounded electric dipole source EM (GESTEM) method and the examination of how the GESTEM method can resolve a thin resistive layer representing underground gas and/or hydrocarbon storage. Numerical modeling studies demonstrate that the loop transient EM (TEM) and magnetotelluric (MT) methods are insensitive to a thin horizontal resistor at depth because they utilize horizontal currents. In contrast to these standard EM methods, the GESTEM method generates both vertical and horizontal transient currents. The vertical transient current interacts with a thin horizontal resistor and causes charge buildup on its surface. These charges produce a measurable perturbation in the surface electric field at early time. The degree of perturbation depends on source waveform. When the GESTEM method is energized with step-off waveform, the perturbation due to a thin horizontal resistor is small. This is because the step-off waveform mainly consists of low frequency signals. An alternative is taking the time-derivative of the step-off responses to approximate the impulse response which includes higher frequency signals. In order to improve degree of perturbation especially due to a localized small 3-D resistor, the diffusion angle of the vertical transient current, 45 should be considered to make vertical currents coupled to a resistive target efficiently. The major drawback of the GESTEM method lies in the fact that GESTEM sounding can not be interpreted using 1-D inversion schemes if there is near-surface inhomogeneity. The marine exploration scenario investigates the physics of marine frequency-domain controlled source EM (FDCSEM) and time-domain controlled source EM (TDCSEM) methods to explore resistive hydrocarbon reservoirs in marine environments. Unlike the marine MT (MMT) method, these two methods are very sensitive to a thin hydrocarbon reservoir at depth because their sources generate vertical as well as horizontal currents. As for the FDCSEM method, the normalized EM peak response occurs where the airwave starts to dominate the seafloor EM response in the background model. This point is a function of source frequency, seawater depth and seafloor resistivity. The peak magnitude of the normalized EM response depends on whether the high concentration of vertical currents can reach and interact with the reservoir effectively. Noise levels of the EM receivers are important factors for successful FDCSEM and TDCSEM survey design. The major benefit of using magnetic field responses over electric ones is that the noise level of magnetic receiver theoretically allows for greater surface coverage compared to that of the electric receiver. Like the GESTEM method, the TDCSEM method also requires the use of a proper transient EM pulse such that the relatively high frequencies are produced. The impulse response of the TDCSEM method is characterized by two-path diffusion of the EM signal. The initial response is caused by faster signal diffusion through the less conductive seafloor, while the later arrivals result from slower diffusion through the more conductive seawater. Therefore, at larger separations, the effects of the seafloor and seawater are separable. This can be useful in reducing the airwave problem associated with the FDCSEM method in shallow marine environments.

Download or read book Electromagnetic Seabed Logging written by Stéphane Sainson and published by Springer. This book was released on 2017-03-30 with total page 549 pages. Available in PDF, EPUB and Kindle. Book excerpt: Seabed logging (SBL) gathers the electromagnetic methods of marine subsoil exploration and more specifically those dedicated to the exploration of oil and gas at sea. Appeared in 2000, these techniques, with more than 500 industrial jobs, present after 15 years of commercial success a discovery record rate of nearly 90 % and seem now to turn the world in the offshore exploration field. Proposing a serious index of the presence of hydrocarbons , electromagnetic SBL coupled with seismic reflection survey is probably the first reliable method for direct detection of hydrocarbons. Complementing the structural concepts of oil exploration used since the 1920s, the SBL now radically modifies the approach and the philosophies of exploration especially those then including drilling and well logging activities. Electromagnetic Seabed Logging: a new tool for oil and gas prospecting, which original publication in French was in 2012, presents these methods, its principles, advantages, limitations, instruments, modeling and applications. It is also designed to be a tool for a reflection on the use of electromagnetic energy for the exploration in a conductive medium as sea water thus setting the theoretical and practical limits of these investigations for future developments. This book is intended of course for the geophysicists and the petroleum geologists, but also for the earth scientists, the reservoir engineers and the log analysts

Download or read book Three dimensional Finite element Time domain Modeling of the Marine Controlled source Electromagnetic Method written by Evan Schankee Um and published by Stanford University. This book was released on 2011 with total page 207 pages. Available in PDF, EPUB and Kindle. Book excerpt: The survey design and data interpretation of the marine controlled-source electromagnetic (CSEM) method require modeling of complex and often subtle offshore geology with accuracy and efficiency. In this dissertation, I develop two efficient finite-element time-domain (FETD) algorithms for the simulation of three-dimensional (3D) electromagnetic (EM) diffusion phenomena. The two FETD algorithms are used to investigate the time-domain CSEM (TDCSEM) method in realistic shallow offshore environments and the effects of seafloor topography and seabed anisotropy on the TDCSEM method. The first FETD algorithm directly solves electric fields by applying the Galerkin method to the electric-field diffusion equation. The time derivatives of the magnetic fields are interpolated at receiver positions via Faraday's law only when the EM fields are output. Therefore, this approach minimizes the total number of unknowns to solve. To ensure both numerical stability and an efficient time-step, the system of FETD equations is discretized using an implicit backward Euler scheme. A sparse direct solver is employed to solve the system of equations. In the implementation of the FETD algorithm, I effectively mitigate the computational cost of solving the system of equations at every time step by reusing previous factorization results. Since the high frequency contents of the transient electric fields attenuate more rapidly in time, the transient electric fields diffuse increasingly slowly over time. Therefore, the FETD algorithm adaptively doubles a time-step size, speeding up simulations. Although the first FETD algorithm has the minimum number of unknowns, it still requires a large amount of memory because of its use of a direct solver. To mitigate this problem, the second FETD algorithm is derived from a vector-and-scalar potential equation that can be solved with an iterative method. The time derivative of the Lorenz gauge condition is used to split the ungauged vector-and-scalar potential equation into a diffusion equation for the vector potential and Poisson's equation for the scalar potential. The diffusion equation for the time derivative of the magnetic vector potentials is the primary equation that is solved at every time step. Poisson's equation is considered a secondary equation and is evaluated only at the time steps where the electric fields are output. A major advantage of this formulation is that the system of equations resulting from the diffusion equation not only has the minimum number of unknowns but also can be solved stably with an iterative solver in the static limit. The developed FETD algorithms are used to simulate the TDCSEM method in shallow offshore models that are derived from SEG salt model. In the offshore models, horizontal and vertical electric-dipole-source configurations are investigated and compared with each other. FETD simulation and visualization play important roles in analyzing the EM diffusion of the TDCSEM configurations. The partially-'guided' diffusion of transient electric fields through a thin reservoir is identified on the cross-section of the seabed models. The modeling studies show that the TDCSEM method effectively senses the localized reservoir close to the large-scale salt structure in the shallow offshore environment. Since the reservoir is close to the salt, the non-linear interaction of the electric fields between the reservoir and the salt is observed. Regardless of whether a horizontal or vertical electric-dipole source is used in the shallow offshore models, inline vertical electric fields at intermediate-to-long offsets are approximately an order of magnitude smaller than horizontal counterparts due to the effect of the air-seawater interface. Consequently, the vertical electric-field measurements become vulnerable to the receiver tilt that results from the irregular seafloor topography. The 3D modeling studies also illustrate that the short-offset VED-Ex configuration is very sensitive to a subtle change of the seafloor topography around the VED source. Therefore, the VED-Ex configuration is vulnerable to measurements and modeling errors at short offsets. In contrast, the VED-Ez configuration is relatively robust to these problems and is considered a practical short-offset configuration. It is demonstrated that the short-offset configuration can be used to estimate the lateral extent and depth of the reservoir. Vertical anisotropy in background also significantly affects the pattern in electric field diffusion by elongating and strengthening the electric field in the horizontal direction. As the degree of vertical anisotropy increases, the vertical resistivity contrast across the reservoir interface decreases. As a result, the week reservoir response is increasingly masked by the elongated and strengthened background response. Consequently, the TDCSEM method loses its sensitivity to the reservoir.

Download or read book lectrographies de fond de mer une r volution dans la prospection p troli re written by SAINSON Stéphane and published by Lavoisier. This book was released on 2012-05-02 with total page 564 pages. Available in PDF, EPUB and Kindle. Book excerpt: L’électrographie de fond de mer (EFM) regroupe les méthodes électromagnétiques d’exploration du sous-sol marin et plus spécifiquement celles dédiées à la prospection des hydrocarbures en mer. Apparues commercialement en 2000, ces techniques, avec plus de 500 opérations industrielles, présentent après 10 ans de succès commerciaux un taux record de découverte de près de 90 %, et semblent aujourd’hui bouleverser la donne en matière de recherche pétrolière offshore. En proposant un indice de présence d’hydrocarbures sérieux, l’EFM couplée à la sismique réflexion est probablement la première méthode fiable de détection directe des hydrocarbures. Complétant les concepts structuralistes de la prospection indirecte en vigueur depuis les années 1920, l’EFM modifie aujourd’hui radicalement l’approche et les philosophies d’exploration, en particulier celles incluant en aval les activités de forages et de diagraphies de fond de trou. S’appuyant sur les lois de l’électromagnétisme (équations de Maxwell), Électrographies de fond de mer décrit et analyse en détail les principes physiques, les méthodes, les techniques et les technologies mis en œuvre ou en voie de l’être. De plus, une note historique montrant l’évolution des idées, des concepts et des matériels depuis les années 1930, dates des premières tentatives, complète chaque chapitre. Synthèse unique, cet ouvrage abondamment illustré constitue un véritable outil de réflexion sur l’utilisation en prospection de l’énergie électromagnétique en milieu conducteur (eau de mer) fixant ainsi les limites théoriques et pratiques de ces investigations pour les développements à venir. Destiné aux géophysiciens et géologues du pétrole, il sera également utile aux physiciens du globe, aux ingénieurs réservoir, aux diagraphistes, aux log analysts, ainsi qu’à tous les étudiants en géosciences.

Download or read book Natural Electromagnetic Fields in Pure and Applied Geophysics written by Kalyan Kumar Roy and published by Springer Nature. This book was released on 2020-02-22 with total page 605 pages. Available in PDF, EPUB and Kindle. Book excerpt: This research monograph presents all the branches of geophysics based on natural electromagnetic fields and their associated subjects. Meant for postgraduate and research level courses, it includes research guidance and collection of magnetotelluric data in some parts of Eastern India and their qualitative and quantitative interpretation. Specific topics highlighted include (i) Electrotellurics, (ii) Magnetotellurics, (iii) Geomagnetic Depth Sounding and Magnetometer Array Studies, (iv) Audio Frequency Magnetotellurics and Magnetic Methods, (v) Marine Magnetotelluric and Marine Controlled Source Electromagnetic Methods, (vi) Electrical Conductivity of Rocks and Minerals and (vii) Mathematical Modelling and Some Topics on Inversion needed for Interpretation of Geoelectrical Data.

Download or read book Introduction to Controlled Source Electromagnetic Methods written by Anton Ziolkowski and published by Cambridge University Press. This book was released on 2019-03-07 with total page 349 pages. Available in PDF, EPUB and Kindle. Book excerpt: An introduction to the theory and practical application of CSEM methods to explore whether subsurface structures contain hydrocarbons.

Download or read book Developments in Geophysical Exploration Methods 4 written by A.A. Fitch and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 206 pages. Available in PDF, EPUB and Kindle. Book excerpt: Geophysical prospecting is an applied science and the range of scientific principles to be applied is very wide. In this collection of original papers, the application of many different principles is described in the search for sulphides, other metallic ores and radioactive deposits. The papers are all concerned with surface observations and cover both the theory and the practice of the methods used. In all cases the advan tages and disadvantages of the methods are described and their role in the detection of mineral deposits is discussed and placed in context. Electromagnetic methods are covered in detail, involving the use of both electric and magnetic field effects. Techniques are described involv ing observations both at a number of discrete frequencies and with continuously changing frequency. In spite of the diversity of method it is interesting to note the strong links between the papers; two chapters, for example, start from the same fundamental illustration, first published by Won, of the basic relationship between source frequency, ground con ductivity and depth of penetration. The all-important economic aspects are not forgotten and the first chapter assesses the statistics of performance and describes their use in the shaping and management of an exploration programme. The editor takes this opportunity to thank the busy men who have set aside time to write these contributions.

Download or read book Electromagnetic Methods in Applied Geophysics written by Misac N. Nabighian and published by SEG Books. This book was released on 1988 with total page 989 pages. Available in PDF, EPUB and Kindle. Book excerpt: As a slag heap, the result of strip mining, creeps closer to his house in the Ohio hills, fifteen-year-old M. C. is torn between trying to get his family away and fighting for the home they love.

Download or read book The Geoelectrical Methods in Geophysical Exploration written by Mikhail Semenovich Zhdanov and published by Elsevier Science & Technology. This book was released on 1994 with total page 892 pages. Available in PDF, EPUB and Kindle. Book excerpt: Hardbound. This volume deals with electrical methods as used in applied geophysics. There are 14 chapters. The first four chapters comprise a handbook of information needed in applied electrical geophysics. The next three chapters deal with three standard techniques: Direct Current (DC), Magnetotelluric (MT) and Controlled-Source Electromagnetic (EM) methods. Chapters 8 - 11 develop important aspects of the subject which are common to all three standard techniques. These common aspects include ambiguity and insensitivity, data acquisition, modeling and simulation, and interpretation. Chapters 12 and 13 cover experience with electrical methods in the solution of a wide variety of practical problems.

Download or read book Advances in Electromagnetic Geophysical Exploration written by Jin Li and published by Frontiers Media SA. This book was released on 2024-01-19 with total page 128 pages. Available in PDF, EPUB and Kindle. Book excerpt: Electromagnetic exploration is one of the earliest and most widely used geophysical exploration techniques. Electromagnetic methods, such as magnetotelluric (MT), audio magnetotelluric (AMT), transient electromagnetic method (TEM), and controlled source electromagnetic method (CSEM), have made a great contribution to industrialization and urbanization by discovering underground deposits of various resources. Driven by the latest progress in electronics and intelligent algorithms, electromagnetic exploration is developing at a high speed. Many challenges faced by traditional geophysical methods are now solvable. Emerging sensing technology and signal processing technology greatly improves the accuracy of electromagnetic methods in many applications. At the same time, such technologies promoted the development of new geophysical theories and methods.

Download or read book Geophysical Field Theory and Method Part B written by Alex Kaufman and published by Academic Press. This book was released on 1994-02-03 with total page 231 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book contains information about the theory of electromagnetic fields in conducting mediums. It describes the theoretical foundation of electromagnetic methods used in all areas of exploration geophysics, including a study of the earth's deep layers. This book will be useful for research and exploration geophysicists, electronic engineers, and graduate and undergraduate students in university geophysics departments.. Electromagnetic fields in conducting media. Physical principles of electromagnetic methods applied in geophysics. Relationship between electromagnetic fields and parameters of a medium

Download or read book Geophysical Field Theory and Method Part C written by Alex Kaufman and published by Academic Press. This book was released on 1994-02-11 with total page 349 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book contains information about the theory of electromagnetic fields in conducting mediums. It describes the theoretical foundation of electromagnetic methods used in all areas of exploration geophysics, including a study of deep layers of Earth. This book will be useful for research and exploration geophysicists, electronic engineers, and graduate and university geophysics departments.Key Topics Covered Include:. Electromagnetic fields in conducting media. Physical principles of electromagnetic methods applied in geophysics. Relationship between electromagnetic fields and parameters of a medium

Download or read book Mining Geophysics written by D. S. Parasnis and published by Elsevier. This book was released on 2013-10-22 with total page 373 pages. Available in PDF, EPUB and Kindle. Book excerpt: Methods in Geochemistry and Geophysics, 3: Mining Geophysics focuses on the geophysical methods of ore prospecting, including radioactivity, collection of geophysical data, and field measurements. The manuscript first highlights the role of geophysics in ore prospecting and the general aspects of collection and presentation of geophysical data. Discussions focus on classification of geophysical methods, radioactivity, collection of preliminary information, field measurement, and isoanomaly curves. The text then surveys magnetic and self-potential methods, as well as the general magnetic properties of rocks, geomagnetic field, magnetometers, transverse magnetization, and measurement of self-potentials. The publication ponders on electromagnetic, electrical, and induced polarization methods. Topics include classification of electromagnetic methods; use of two frequencies in electromagnetic prospecting; moving source-receiver methods; electrode configurations in resistivity methods; and resistivity measurements in boreholes. The text also examines gravity, seismic, and airborne magnetic and electromagnetic methods. The manuscript is a valuable source of information for geologists and mining engineers.

Download or read book The Magnetotelluric Method written by Alan D. Chave and published by Cambridge University Press. This book was released on 2012-04-26 with total page 571 pages. Available in PDF, EPUB and Kindle. Book excerpt: A rigorous introduction to magnetotelluric imaging of Earth's electrical conductivity and structure, for researchers, advanced students and industrial practitioners.

Download or read book Electromagnetic Methods in Applied Geophysics Theory written by Misac N. Nabighian and published by . This book was released on 1988 with total page 544 pages. Available in PDF, EPUB and Kindle. Book excerpt: As a slag heap, the result of strip mining, creeps closer to his house in the Ohio hills, fifteen-year-old M. C. is torn between trying to get his family away and fighting for the home they love.

Download or read book Principles of Electromagnetic Methods in Surface Geophysics written by Alex A. Kaufman and published by Elsevier. This book was released on 2018-10-30 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Principles of Electromagnetic Methods in Surface Geophysics contains information about the theory of electromagnetic fields in a conducting media. It describes the theoretical and physical principles of the main geophysical methods using electromagnetic fields, including frequency and transient soundings, electromagnetic profiling, and magnetotelluric soundings. Special attention is paid to models and signal processing methods used in modern exploration geophysics for groundwater, mineral and hydrocarbon exploration.