Electrical Exploration Methods Research Articles

The Chemerpil gravimagnetic anomaly as a modern reflection of the unique Precambrian volcanic-plutonic magnetite-gold mineralisation structure of the Ukrainian Shield (Middle Bug area)

The article is devoted to the peculiarities of genesis and mineralogical potential of Chemerpol iron-magnetite structure, its difference from other similar objects of Central Bug area. As an independent geological-geophysical object it was established according to the data of gravimetric and magnetometric survey of medium scale as a complex localised maximum of subisometric shape with diameter of 1.7 km and area of 2.8 km2. In regional structural and tectonic terms, this maximum is confined to the Sinitsiv block of the Golovanovsk suture zone. As of today, the Chemerpol structure has been sufficiently investigated by mapping drilling and various geophysical methods at the level of the crystalline basement surface. Based on the obtained data, the main petrophysical complexes involved in its structure have been determined. The industrial and mineralogical potential of the Chemerpolska structure is estimated at 100 million tons of magnetite quartzites and carbonate formations, as well as 2 tons of exogenous gold in the weathering crust. No estimates have been made of the underlying gold deposits. Copper mineralisation, represented by the natural copper, chalcopyrite and chalcosine, has been identified in the weathering crust and crystalline basement. By structural and tectonic features, petrophysical and mineralogical diversity, the Chemerpolska structure can be attributed to local pipe volcanic-magmatic objects. Its closest well-studied geological analogues may be such Precambrian "stratified" iron-oxide-gold-copper deposits as Solobot and others of the Carajas ore district in Brazil. For geological verification of new conclusions about the peculiarities of the Chemerpol structure and its actual ore potential, it is necessary to continue its study based, first of all, on the data of targeted structural exploration drilling and deep seismic and electrical exploration methods. The economic efficiency of extraction of the main mineral components of the Chemerpolska structure - gold and magnetite iron - can be increased due to the accompanying use of non-metallic calcifiers for the manufacture of sintering flux, soil deoxidation, raw materials for road pavement.

Application of Electrical Prospecting Methods for Monitoring the Condition of Earth Dam in the Almaty Region of Kazakhstan

This article deals with the issue of diagnostics of the physical condition of earthen dams, taking into account seasonal changes in the water level of hydraulic structures using electrical exploration methods. The simplicity of the method, the accuracy of measurements of geophysical parameters, and the availability of software packages for the processing, interpretation, and visualization were the basis for the choice of method. The method of electrical resistivity and self-potential was chosen. The methodology, technique, technology of field surveys, processing, and geological interpretation of the study results are given. A comparative analysis of the obtained geophysical parameters of seasonal measurements is given. The research results are given in the form of sections of the resistivity model and self-potential isolines.

Обнаружение техногенных коллекторов и оценка фильтрационных свойств барьерных целиков ликвидированных шахт

An integrated approach to identification of man-made reservoirs within mining allotments of abandoned coal mines is proposed and tested, as well as determination of their methane content, which is based on the combined application of electrical exploration methods, measurement of ground-level concentrations of atmospheric gases and studies of mine methane isotopy. The boundaries of a man-made gas reservoir formed by the mined-out space of two abandoned coal mines were identified. A significant difference has been demonstrated between the content of light carbon isotopes of coal mine methane in the manmade reservoir and underlying coal seams. The paper discusses the impact of atmospheric pressure changes on the increase of ground-level methane concentrations. Drilling of gas-drainage boreholes in the decompression zones of the coal mass with subsequent connection to vacuum pumping stations providing methane collector degassing is recommended to limit methane release from the man-made collector into buildings and facilities located within the mining allotment of the abandoned mines.

Regularities of Changes in the Surface Impedance of the Medium Over Hydrocarbon Deposits Under the Influence of Radio Pulsed Signals

The interaction of radio pulse signals in an anisotropic medium over hydrocarbon deposits has been studied. During the experiments, computer simulation of the characteristics of anisotropic media was performed. The dependences of the real, imaginary, and phase components of the characteristics of the surface impedance of an anisotropic medium over hydrocarbons on its dielectric constant, the frequency of radio pulse signals interacting with it, and the number of spectrum harmonics of the latter are obtained. Based on the research results, recommendations are given to improve the accuracy of determining the boundaries of hydrocarbon deposits using electrical exploration methods based on the use of radio pulse signals. The research results can be applied in prospecting geophysics for the discovery of oil and gas deposits.

Application of electrical prospecting methods for technogenic bodies (stored wastes of the mining industry) studies: review

The world experience of using electrical exploration methods in the study of technogenic bodies is considered, in particular: determining the zoning of tailings, groundwater migration routes and the stability of dams. The ongoing research demonstrates the high efficiency of combining the methods of geophysics, geochemistry, and hydrology. On the example of mining dumps located on the territory of the Kemerovo region and the Republic of Tyva, the achievements of the interdisciplinary team of the IPGG SB RAS are shown. The use of electrical resistivity tomography and magnetic prospecting in combination with geochemical mapping and gas survey made it possible to reveal the internal structure of tailings and dumps, outline watered horizons, and determine the transport of highly mineralized solutions to groundwater. Obtained results became the basis for creating a methodology for a comprehensive study of tailings and dumps, assessing the danger of technogenic bodies, and developing methods for minimizing their impact on the environment and the population of settlements.

АНАЛИЗ ЭФФЕКТИВНОСТИ ПРОГРАММНЫХ КОМПЛЕКСОВ ЭЛЕКТРОТОМОГРАФИИ ДЛЯ ИНТЕРПРЕТАЦИИ ПОЛЕВЫХ ДАННЫХ В СЕЙСМОАКТИВНЫХ РАЙОНАХ (НА ПРИМЕРЕ ГОРНОГО АЛТАЯ)

Since 2004, regular investigations with the use of electrical exploration methods have been conducting by researchers of Institute of Petroleum Geology and Geophysics SB RAS on the territory of the Gorny Altai. The electrotomography method is used to construct geoelectric models of the upper section part to depths of several tens of meters. One of the important tasks of this method is to determine characters of fault zones. Large regional Cenozoic faults are distinguished by significant shifts and are usually well manifested in relief. Intradepression interblock faults overlaid by sedimentary deposits are hard to identify by geological methods, but they are reflected mainly by zones with a reduced value of electrical resistance in sections according to electrotomography data. The paper considers practical examples of the ET method use for studying fault structures of the Gorny Altai. Analysis of the accumulated volume of electrotomography field data allowed researchers to compile typical models simulating the fault structures of this territory. The results of simulated data inversion obtained by numerical modeling of fault zones of the Gorny Altai using well-known third-party programs and proprietary developments are compared. The capabilities of different software systems are analyzed for interpretation of electrotomography data.

About the role of associate professor of Kazan University R.K. Khabibullov in the development and implementation of electrical exploration methods in Tatarstan

About the role of associate professor of Kazan University R.K. Khabibullov in the development and implementation of electrical exploration methods in Tatarstan

Substantiation of the geoelectric model of the freshwater reservoir in the water areas

The relevance of the search for fresh water exists for large areas of the planet. Often arid regions are washed by saline reservoirs, under the waters of which lie significant volumes of fresh water. To search for these waters, it is rational to use aquatic methods of electrical exploration. The substantiation of the geoelectrical model of a freshwater reservoir in offshore areas for numerical modeling of an electrical survey signal at direct current and during a transient process is given. The result of the study shows the rationality of using electrical exploration methods for the search and exploration of freshwater reservoirs in the water areas.

Application of the improved multi-electrode electrical exploration methods for groundwater investigation in Vientiane Province, Laos

The purpose of this study is to evaluate the effectiveness of the multi-electrode electrical resistivity methods and to better understand the aquifers in Laos. The improved multi-electrode electrical exploration (IMEE) methods and a SuperSting R8/IP system with 56 electrodes have been used to measure ten 2D-electrical resistivity and three induced polarization profiles, of maximum length 550 m, at four sites in the Phonhong and Thoulakhom districts of Vientiane province, Laos. The results revealed moderate resistivity regions (18–80 Ohm m) that correspond well with low chargeability values (0–21 ms) at depths from 22 to 100 m, indicating possible suitable layers of good quality groundwater. These results agree well with data from borehole 1 drilled in the Phonhong district, which indicated the location of the water table at 20 m depth where samples extracted from the drill cores have been identified as gravel and siltstone. Analyses of water samples from different existing and new wells in the survey areas, including Total dissolved solids (TDS), Electrical conductivity (EC) and pH, revealed mean values lower than the contamination thresholds, confirming that the water is suitable for drinking without causing health risk. The obtained results provide new information leading to a better understanding of the structural framework of the study area. These results also demonstrate that the IMEE methods may be an efficient tool for groundwater investigation in Vientiane Province, Laos, and these methods can be applied for groundwater exploration all over the world.

ПРИМЕНЕНИЕ ЭЛЕКТРОРАЗВЕДОЧНЫХ И АТМОГЕОХИМИЧЕСКИХ ТЕХНОЛОГИЙ ПРИ СЕЙСМИЧЕСКОМ МИКРОРАЙОНИРОВАНИИ ТОННЕЛЬНОГО ПЕРЕХОДА ЧЕРЕЗ МАРКОТХСКИЙ ХРЕБЕТ

Aim. Investigation of the electrical exploration effectiveness and atmogeochemical technologies for detecting discontinuous and folded tectonic disturbances during seismic microzoning of the tunnel crossing over the "Markotkhsky ridge" Task. Study of the tectonic disturbance degree and flooding of the flysch strata using spatial electrical filtration, electropotential tomographic sensing, and atmogeochemical measurements along the tunnel route using data from route surveys and drilling at the tunnel design site. Research methods. 1) Field electrical survey measurements of spatial electrical filtration and electropotential tomographic sensing and with installations of multidirectional electric field excitation for" highlighting " target objects. 2) Using a multi-variant system for presenting field data in the form of tomograms and in the form of electro-profiling and sounding to identify destructive zones related to tectonically disturbed rocks and flood zones. Research results. The analysis of domestic and foreign publications on the use of electrical exploration methods in seismic microdistricting of design, construction and operation of critical facilities is performed. On the example of a tunnel crossing over the Markotkhski ridge: 1) geological, geo-ecological, and seismological characteristics of the area of engineering and geophysical research are considered; 2) the field studies of spatial technologies electric filtrazione, electropotentials tomographic probing and atmogeochemical of observations are produced; 3) the heterogeneity of fliteway thickness laterally and quasioperational this thickness on the electrical properties at depth is shown; 4) as a result poperechnogo analysis curves electropotentials tomographic probing, as well as charts of the spatial electric filtrational and atmogeochemical measurements of an tectonically disturbed and watery areas are identified; 5) the degree of differentiation of the flysch thickness by the values of the specific electrical resistance was estimated using a pseudo-section constructed in the Res2Dinv program. Conclusions. The technologies of electropotential tomographic sounding and spatial electric filtration are unique in terms of mobility and simplicity of field measurements, subsequent geological and geophysical interpretation of anomalous values of the electric field based on its redistribution in tectonically and technogenically disturbed geological structures. The result is the identification of places of development of tectonic discontinuities and watered zones, information about which makes it possible to predict, along with the seismicity of the rock mass inside the tunnel, possible places of potential collapse and flooding during the design, construction and subsequent operation of tunnel crossings. A significant achievement of the experiments can be attributed to the identification of the possibility of electroprobing the flysch strata with steeply-and obliquely-lying layers by dipole electric exploration installations. The proof is that the growth of the right branches of the probing curves does not exceed 45°. Consequently, the steeply-and obliquely-lying flysch strata can be considered heterogeneous laterally and quasihomogeneous in depth in terms of electrical properties.

Three‐dimensional electrical exploration methods for the mapping of polymetallic targets in Gansu Province, China

ABSTRACTWe describe a three‐dimensional electrical exploration system, and its use in carrying out a three‐dimensional survey on a polymetallic deposit located in China's Gansu Province. A time‐domain‐induced polarization method, along with a controlled‐source audiomagnetotelluric method, was used to survey the same station points for comparison. Then, a three‐dimensional inversion based on the incomplete Gauss–Newton method (for time‐domain‐induced polarization) and a nonlinear conjugate gradient (for controlled‐source audiomagnetotelluric) method were developed and applied in order to model the data sets. Four subsurface targets were mapped by the three‐dimensional electrical exploration method. A strong correlation was found between the zones of the revealed ore‐bearing anomalies and the geological setting. Using the results of the three‐dimensional electrical exploration, we revealed the spatial distribution of the ore‐bearing stratum, as well as the relationship between the ore bodies and the stratum. The results potentially provided evidence for future interpretations of deep geological structures, along with evaluations of mineral resources.

ИССЛЕДОВАНИЯ ПО ОБНАРУЖЕНИЮ ЭФФЕКТА ХОЛЛА В ГЕОЛОГИЧЕСКОЙ СРЕДЕ (ОБОСНОВАНИЕ ПОВТОРНЫХ ЭКСПЕРИМЕНТОВ)

This work is devoted to identifying the influence of the Hall effect in the geological environment on the electrical exploration methods data on the example of controlled source transient electromagnetic (TEM) method. It summarizes the results of previous theoretical studies, as well as the results of the summer field work in 2018 and the authors' recommendations for further field studies planned for the summer of 2019. Much attention is paid to the aspects of the field experiment, as well as the conditions of its correctness. The estimation of the Hall conductivity on the basis of already available results is given.

Research of the geological factors of coal deposits in the south of the Far East by electrical exploration methods

Coal deposits in the south of the Far East are characterized by complex geological factors, which is due to the inclined occurrence the enclosing layers and coal seams, high pressure of underground water, the presence of water-bearing sandy-pebble and gravel-pebble sediments, the presence of numerous faults and various inclusions, the presence of island permafrost. In the exploration of deposits, the low efficiency of previously used electrical exploration methods, including electrical sounding and profiling, was noted. In this paper, it is shown that increasing efficiency in the solution of some mining and geological tasks is associated with the use of the electrical tomography method. This method has advantages in the conditions of weak differentiation of rock resistivity due to the high density of obtained parameters. With the use of electrical tomography, the tasks in the allocation of tectonic disturbances and coal seams uplift under quaternary sediments, estimation of the landslide slopes structures on the coal pit edges have been solved. Successful results were obtained in isolating the weathered layer of the bedrock, sandstone outcrops under the soil-vegetative layer in the upper part of the section, the bedrock surface on the deposit’s flanks and the covers of effusive rocks on the surface.

Geology and geophysical exploration of base metals in Victoria

provides the best exposed section across the Lachlan Fold Belt, which extends from eastern Tasmania through central and eastern Victoria into New South Wales. Western Victoria also contains the eastern parts of the Delamerian Fold Belt. The rocks include the late Proterozoic to Lower Carboniferous sequences that were folded in the Palaeozoic up to the Early Carboniferous Kanimblan Orogeny. The rocks are traversed by thrust faults more or less parallel to the north-south structural grain. The largest faults separate rocks with different ages and structural histories, and have been used to subdivide Victoria into seven structural zones. The oldest mapped rocks are Late Proterozoic or Cambrian and are either calc-alkaline island arc-type volcanics (mainly in the west) or mid oceanic ridge basalts (mainly in central Victoria). The island arc-type volcanics have potential for major volcanic-hosted massive sulphide deposits (VHMS) deposits. The Wickliffe and Hill 800 prospects are in this environment. Small copper-gold deposits are hosted by tholeiitic basalts. An example is the Mount Ararat Prospect which contains an inferred resource in excess of 1 million tonnes of 2.7% copper, 10 g/t silver and 0.6 g/t gold. Electrical exploration methods were ineffective due to a conductive surface layer. Magnetic induced polarization defined anomalous responses coincident with the mineralisation. In eastern Victoria, two cycles of transtensional rifting generated and preserved voluminous silicic volcanics and marine sediments. The Silurian cycle formed the Cowombat Rift, host to significant base metal deposits. These include the Wilga and Currawong VHMS deposits near Benambra. Both were geophysical discoveries. The time-domain electromagnetic surveys showed the massive sulphides were associated with conductivity responses and the aeromagnetic data showed discrete magnetic responses over the mineralisation. The total reserves at Wilga were 3.93 million tonnes of 3.64% copper and 5.44% zinc. The unmined Currawong orebody resource is 8.9 million tonnes of 1.9% copper and 4% zinc. Early Devonian transtension formed the Buchan Rift and smaller basins, into which volcanics and/or marine sediments were deposited. These host the possible Irish-style carbonate-hosted lead-zinc mineralisation at Back Creek, and possible Tennant Creek style mineralisation at Nowa Nowa. The Nowa Nowa deposits were identified from intense magnetic responses and led to the discovery of magnetite - haematite +- chalcopyrite mineralisation. The mineralisation within the Cambrian Mount Stavely Volcanic Complex at Thursdays Gossan, while low grade and uneconomic, is significant because it is the first porphyry copper style identified in western Victoria. It offers the possibility of mineralised porphyry systems being formed in a favourable environment potentially equivalent to other high-gold VHMS deposits in southeastern Australia. In eastern Victoria mixed I-, S- and A-type granites were intruded in the Early Devonian; several broke through to the surface and formed calderas. Some of the granites around the Buchan Rift, at Dogwood and Sunday Creek, are host to porphyry mineralisation. Major government initiatives to encourage mineral exploration have led to the collection of regional semi-detailed geophysical data and so improved the quality and speed of geological mapping. For the first time, the explorer now has access to low cost, high-quality regional scale magnetic, radiometric, digital terrain and gravity data to include in a modern exploration program and to help determine mineral exploration targets. For base-metal exploration, they are particularly valuable. In the highlands of eastern Victoria outcrop is generally good but access can be difficult while in western Victoria geophysical techniques are required to focus exploration beneath cover. In both regions, the new data have highlighted new potential.

Principles of time‐domain electromagnetic (TDEM) sounding

The term time‐domain electromagnetic sounding can stand for any of a variety of electrical exploration methods in which the transient response of the Earth to a pulse‐like magnetic field is measured. Such methods have been described in the geophysical literature since the 1930s and are currently being used quite successfully in mineral exploration and civil engineering studies. It has become standard practice to call them “TEM” (for transient electrical methods). The TDEM technique (time‐domain electromagnetic method) described here is included within the broader TEM category.

Electrical Methods in Geophysical Exploration of Deep Sedimentary Basins

The applications of deep probing electrical exploration methods are extensive. Primarily they are used in the general exploration of deep or shallow sedimentary basins, the exploration of the Earth’s deep crust, and in prospecting for oil and gas, geothermal and groundwater reservoirs. Some of the methods are also used in earthquake prediction research and in deep and shallow environmental studies and geotechnical work. This wide application highlights the importance of the electrical methods in practical geophysics and has led to the development of many different techniques tailored to these varying types of geological goal. The stated objective of this book is to provide a working knowledge of these deep-penetrating electrical methods, with specific reference to sedimentary basins. It is aimed at the practising geologist or geophysicist, especially those in the petroleum industry, and aims to serve as a guide, particularly in survey planning and data interpretation. The text concentrates on concepts, methods, exploration strategy and interpretation. Accompanying topics of mathematical equation derivation, instrumentation, field procedures and data processing are all covered but in a more limited way. The text opens with two introductory chapters, the first discussing the role of electrical methods in a selection of common fields of exploration, highlighting the importance and central role they play. Chapter 2 covers the electrical properties of sedimentary rocks briefly-the material is familiar but may be covered unsatisfactorily for a general reader. The main body of the book is divided into three chapters, discussing separately direct current resistivity methods, natural-source electromagnetic methods and controlled-source electromagnetic methods. Each chapter introduces its method with an overview of how it is applied, the data collected, the assumptions inherent to it, the limitations of its application and the associated concepts and terminologies appropriate to that method, for example the skin-depth concept in electromagnetic studies. The background theory to the methods is discussed, little attempt is made to derive the mathematical equations from first principles, and the discussion concentrates mainly on the practical aspects of modelling and data analysis. Variations of each method are discussed to highlight their advantages and disadvantages for particular survey objectives in terms of cost, data quality and sensitivity to a particular target. This gives a good practical guide to survey design. The final chapter reviews specifically the possibilities for the direct detection of petroleum. The direct measurement of the resistivity of oil and gas reservoirs, electromagnetic reflection methods and induced polarization methods, amongst others, are all discussed historically in the context of their success in directly determining the existence of hydrocarbons. This is given as a review of past work and no new contribution is attempted. This is a very readable and refreshing introductory book for some of the more practical aspects of the electrical methods used in geophysics. Often its brief treatment of some of the underlying theory is frustrating-this could be covered in a way more satisfying to the general reader by the addition of

The Use of Electrical Methods in Recent Exploration for Epithermal Gold Deposits in Japan

In general, electrical exploration methods are not very effective for finding a resistive zone, as compared with a conductive zone. Because of this, it is particularly difficult to distinguish a resistive zone from the surrounding area when its size is small and it is situated at depth. Using electrical exploration methods, the targets for epithermal gold deposits are the highly resistive quartz vein systems and associated silicified zones. Thus the detection of them by electrical methods was thought to be difficult in the past.The Metal Mining Agency of Japan (MMAJ), in its recent exploration, has applied electrical methods with some degree of success, at the Hikiji area in the central Kyushu island of Japan. I will present some of these data and discuss the effectiveness and limitations of using electrical methods for finding epithermal gold deposits.

Integral equation method for the quasi-three-dimensional problem of the electromagnetic field in a nonhomogeneous conducting medium

The recent development of electrical exploration methods of the Earth's crust using artificial field sources stimulates mathematical modeling of three-dimensional electromagnetic fields in conducting media. The problem of computing the field of arbitrary sources in a horizontally stratified conducting medium has been fully solved, but the actual structure of the Earth's interior often does not fit this model. The attempts to examine a three-dimensional model of the medium lead to complex problems, whose numerical solution is so far only possible under highly restrictive assumptions on the size and the shape of the nonhomogeneities, etc. It is therefore relevant to consider quasi-three-dimensional problems, which determine the field t~l: a 3D source in a 2D-nonhomogeneous medium. In this paper, we solve this problem by the integral equation method. We consider a model of the Earth described by the following conductivity distribution:

EXPLORATION OF HIGH RESISTIVITY BASEMENT USING ELECTRICAL AND MAGNETIC FIELDS OF QUASI‐STATIC POINT SOURCES*

AbstractDetermination of thickness of sediments (usually of high conductivity) overlying a high‐resistivity basement is one of the basic problems of electrical exploration methods. This paper proposes to determine horizontal electrical conductance on the basis of impedance calculated from electrical and magnetic fields of distant quasi‐static (low‐frequency) point sources. Using the proposed method, horizontal conductance of the sediments can be determined also from artificial quasi‐static noise‐impulses coming from sources of unknown position and intensity. The results of analogue modeling and field examples prove the potential of the proposed technique.

Applications of Geophysics in War: ABSTRACT

War-time applications of geophysics come under the heading of military operations and location of essential minerals. In the combat zone, sound ranging helps to locate hostile guns and to adjust friendly artillery. Listening devices determine the approach of submarines or airplanes. Buried munition dumps, shells, and bombs can be located by radio detection devices. Vessels at sea may establish their position by radio-acoustic ranging. Planning of fortifications and harbors and location of construction materials will be aided by seismic refraction, electrical resistivity, and dynamic ground testing. The same methods are applicable to problems involving the construction of railroads, highways, bridges, tunnels, and munitions plants. For the last, added protection is possibl by static-ground-resistance investigations. Salvage operations, location of shipwrecks and practice weapons, are aided by echo-sounding and radio methods. In the second group, geophysics is concerned with the location of water, fuels, and strategic minerals. Water may be found under favorable conditions by electrical and seismic methods, and water wells may be tested by electrical logging. Geophysical foundation investigations are applicable in irrigation, flood-control, and power projects. Magnetic, gravimetric, seismic-reflection, and electrical well-logging methods occupy a prominent place in oil exploration. Coal and lignite deposits may be mapped by geophysical methods. Magnetic, electrical, gravimetric, and seismic exploration methods are now used in a systematic government-sponsored exploration program to uncover vitally needed deposits of bauxite, chromite, manganese, mercury, nickel, tin, and tungsten. End_of_Article - Last_Page 903------------