Academic literature on the topic 'Geochemical dispersion'
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Journal articles on the topic "Geochemical dispersion"
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Diemar, Glen A., Montserrat Filella, Peter Leverett, and Peter A. Williams. "Dispersion of antimony from oxidizing ore deposits." Pure and Applied Chemistry 81, no. 9 (August 4, 2009): 1547–53. http://dx.doi.org/10.1351/pac-con-08-10-21.
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The solubilities of brandholzite, [Mg(H2O)6][Sb(OH)6]2, and bottinoite, [Ni(H2O)6][Sb(OH)6]2, at 25 °C in water have been measured. Solubilities are 1.95(4) × 10-3 and 3.42(11) × 10-4 mol dm-3, respectively. The incongruent dissolution of romeite, Ca2Sb2O7, and bindheimite, Pb2Sb2O7, at 25 °C in 0.100 mol dm-3 aqueous HNO3 was also investigated. Equilibrium dissolved Sb concentrations were 3.3 ± 1.0 × 10-7 and 7.7 ± 2.1 × 10-8 mol dm-3, respectively. These values have been used to re-evaluate the geochemical mobility of Sb in the supergene environment. It is concluded that the element is geochemically immobile in solution and in soils. This was in part validated by an orientation soil geochemical survey over the Bayley Park prospect near Armidale, New South Wales, Australia. Anomalous soil Sb levels are confined to within 100 m of known stibnite mineralization.
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Wang, Jian, and Renguang Zuo. "Quantifying the Distribution Characteristics of Geochemical Elements and Identifying Their Associations in Southwestern Fujian Province, China." Minerals 10, no. 2 (February 18, 2020): 183. http://dx.doi.org/10.3390/min10020183.
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The distribution of geochemical elements in the surficial media is the end product of geochemical dispersion under complex geological conditions. This study explored the frequency and spatial distribution characteristics of geochemical elements and their associations. It quantifies the frequency distribution via mean, variance, skewness and kurtosis, followed by measuring the spatial distribution characteristics (i.e., spatial autocorrelation, heterogeneity and self-similarity) via semivariogram, q-statistic and multifractal spectrum, and further identify the elemental associations based on these distribution parameters using hierarchical clustering. A criterion was defined to identify the importance of parameters in the clustering procedure. A case study processing a geochemical dataset of stream sediment samples collected in southwestern Fujian province of China was carried out to illustrate and validate the procedure. The results indicate that studies of the frequency and spatial distribution characteristics of geochemical elements can enhance the knowledge of geochemical dispersions. The associations identified based on the frequency and spatial distribution parameters are different from those obtained by conventional cluster analysis. Spatial distribution characteristics cannot be neglected when investigating the distribution patterns of geochemical elements and their associations. The findings can enhance the knowledge of the geochemical dispersion in the study area and might benefit the following-up mineral exploration.
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Khalilov, A., Z. Akbarova, K. Khoshjanova, N. Atabaeva, Sh Juraev, and M. Juliev. "Results of mineralogical and geochemical investigations of rocks and ores of productive horizons of sandstone type of Dzhengeldy deposit." IOP Conference Series: Earth and Environmental Science 1068, no. 1 (July 1, 2022): 012006. http://dx.doi.org/10.1088/1755-1315/1068/1/012006.
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Abstract The mineralogical and geochemical study of the productive horizons of the Dzhengeldy site was carried out from 2016 to 2020. It should be noted that each horizon has ore-bearing rocks with similar mineralogical and geochemical characteristics. We studied 2 horizons of the Dzhengeldy site (Maastricht and Lyavlyakan). Below are the results of studying the material composition and geochemical features of rocks and ores from deposits of the productive horizons of the Maastrichtian and Lavlyakan selected for various geochemical subzones: oxidized (oreless, selenium dispersion aureoles, uranium and selenium dispersion aureoles, uranium dispersion aureoles, selenium ores) and unoxidized (selenium dispersion aureoles, uranium and selenium dispersion aureoles, selenium ores, uranium ores, uranium dispersion aureoles, uranium and molybdenum dispersion aureoles, molybdenum dispersion aureoles) parts of zoning. It should be noted that the subzones of uranium-selenium, uranium-molybdenum and molybdenum mineralization localized in the grey part of the section have not been studied due to the lack of samples. The subzone of the uranium-molybdenum dispersion aureoles is represented by only one sample, the subzone of the molybdenum dispersion aureoles is represented by three samples (1 sample from the Lavlyakan horizon, 2 samples from the Maastrichtian horizon).
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Liu, Rui Ping, You Ning Xu, Fang He, Jiang Hua Zhang, Hua Qing Chen, Hai Ling Ke, Gang Qiao, Dong Ying Xu, and A. Ning Zhao. "Environmental Impact by Heavy-Metal Dispersion from the Fine Sediments of the Shuangqiao River, Xiaoqinling Gold Area, China." Advanced Materials Research 518-523 (May 2012): 1929–35. http://dx.doi.org/10.4028/www.scientific.net/amr.518-523.1929.
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Abstract. the sediments is the second pollution source to the water quality of river in mining area, in order to assess the pollution extent of the Shuangqiao River by anthropogenic activity, and establish the geochemical background values and the possible geochemical anomaly range, The authors use Lognormal distribution plots to study the Mercury, Chromium, Cadmium, Lead, Copper, Arsenic, Zinc and Iron dispersion in the fine sediments of the Shuangqiao River. The Lognormal distribution plots are applied to discriminate the geochemical background levels of eight heavy metals from the geochemical anomalies. The result shows that Mercury, Lead are the most heavily pollution which is related to anthropogenic activities, and the concluded geochemical background value is more reasonable than before.
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Siddeeg, Saifeldin M., Nicholas D. Bryan, and Francis R. Livens. "Behaviour and mobility of U and Ra in sediments near an abandoned uranium mine, Cornwall, UK." Environmental Science: Processes & Impacts 17, no. 1 (2015): 235–45. http://dx.doi.org/10.1039/c4em00230j.
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Halley, Scott, John H. Dilles, and Richard M. Tosdal. "Footprints: Hydrothermal Alteration and Geochemical Dispersion Around Porphyry Copper Deposits." SEG Discovery, no. 100 (January 1, 2015): 1–17. http://dx.doi.org/10.5382/segnews.2015-100.fea.
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ABSTRACT Whole-rock lithogeochemical analyses combined with short-wave infrared (SWIR) spectroscopy provide a rapid and cost-effective method for prospecting for porphyry-type hydrothermal systems. Lithogeochemistry detects trace metals to average crustal abundance levels and allows vectoring via gradients of chalcophile and lithophile elements transported by magmatic-hydrothermal ore and external circulating fluids that are dispersed and trapped in altered rocks. Of particular use are alkalis in sericite and metals such as Mo, W, Se, Te, Bi, As, and Sb, which form stable oxides that remain in weathered rocks and soils. SWIR mapping of shifts in the 2,200-nm Al-OH absorption feature in sericite define paleofluid pH gradients useful for vectoring toward the center of the buoyant metal-bearing magmatic-hydrothermal plume.
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Alekseenko, Vladimir, Natalya Shvydkaya, Alexander Puzanov, and Aleksey Nastavkin. "Landscape monitoring studies of the North Caucasian geochemical province." Journal of Mining Institute 243 (June 10, 2020): 371. http://dx.doi.org/10.31897/pmi.2020.3.371.
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The data on the geochemical features of the bedrocks and soils of the province are given. Considerable attention is paid to regional abundances, as well as enrichment and dispersion factors of the chemical elements in landscapes. Using the example of the North Caucasus, it is shown that for such indicators as phytomass, geological, geomorphological, and geobotanical features, it is possible to make a preliminary outlining of regional structures corresponding to geochemical provinces. At the same time, a subsequent geochemical study of these structures remains mandatory. Upon determining certain geochemical associations, geochemical provinces can be basically distinguished; to a large extent, geochemical properties of these accumulated and scattered associations of elements contribute to the regional soil geochemistry. The results of long-term monitoring studies of the North Caucasus geochemical province have shown that the key features of the regional landscapes are due to the composition of bedrock and the presence of a large number of ore deposits and occurrences. The data obtained are the basis for assessing the state of the environment in conditions of increasing anthropogenic impact, and the established regional abundances can be used to assess the degree of pollution in agricultural, residential, and mining landscapes.
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Stajevic, Bosko. "Geochemical haloes of Gold in the Lece ore field - southern Serbia." Annales g?ologiques de la Peninsule balkanique, no. 65 (2003): 93–99. http://dx.doi.org/10.2298/gabp0301093s.
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In the area of the Lece base-metal ore field in the SE part of the Radana Tertiary volcanic complex, prospecting researches, lasting several years was done during the last decade of the last century. In the paper some results are presented and analyzed, especially those concerning the distribution of gold relative to trace elements in the secondary lithogeochemical dispersion haloes. In the assemblage of 8 analyzed trace elements of the Lece lithogeochemical field, Au, Pb, Zn, Ag and Sb show expressive, contrasting and mutually well correlated secondary dispersion haloes. The presented results of geochemical prospecting are considered not to be clearly indicative for epithermal gold mineralization in the polymetallic ore field Lece.
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ΒΑΡΝΑΒΑΣ, Σ. Π. "The contribution of Geochemistry in the assessment of environmental conditions in soils and aquatic systems and in the application of remediation methodologies." Bulletin of the Geological Society of Greece 34, no. 6 (January 1, 2002): 2207. http://dx.doi.org/10.12681/bgsg.16863.
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A main present day geochemical application is the assessment of the environmental conditions prevailing in a variety of natural and anthropogenic environments and the application of remediation methodologies. For this aim geochemical studies lead to the determination of the concentration levels and the source of pollutants. In addition through biogeochemical studies the behavior of pollutants in various environments is determined (i.e. rate of enrichment or dilution in space and time, dispersion processes etc.). On the basis of the results of geochemical studies remediation methodologies and methodologies leading to prevention of toxic elements in getting into the food chain are applied while criteria are put for the quality of soils, water etc. In addition decision makers are helped to make the necessary and right decisions in the management of toxic waste.
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Khansivarova, Nadezda M., Yuri N. Kostyuk, and Vladislav V. Kharchuk. "Microbiological and Geochemical Problems of Urban Areas with Abundant Dispersed Rocks." Journal of Computational and Theoretical Nanoscience 16, no. 11 (November 1, 2019): 4579–83. http://dx.doi.org/10.1166/jctn.2019.8358.
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Aim. The study of microbiological and geochemical processes occurring in the soil strata, composed of dispersed rocks, when they are in contact with the liquid wastes of industrial production in the city of Rostov-On-Don. The most important problems connected with chemical industrial pollution of the geological environment of urban territories situabed in the regions of dispersed rocks deposit evolution are discussed. Methods. Dispersed rocks of the European part of the south of Russia are investigated by the method of laboratory modeling. Results. Olt is shown that technogenic chemical elements entering geological environment with liquid industrial wastes not only worsen ecological state of the environment maintaining existence, but the are a factor of structure formation of dispersed rocks; they also can be a source of feeding for microorganisms, and hence, make more active microbiogeochemical reactions in dispersion ground strata. The number ahd composition of microflora of dispersion rocks are experimentally studied. The assessment of the possible effect of microbiological processes occurring in dispersed rocks on their engineer and geological properties is given. Findings. Chemical pollution of masses that are composed of dispersed rocks, on urban ecosystems and its intensity are the result of waste water infiltration and chemical activity of dispersion rocks. It leads to the development of engineer and geochemical processes disturbing physical–chemical and biogeochemical equilibrium in dispersed thickness and homeostasis of natural-technical system on the whole, that can worsen conditions of man vital activity as well. The assessment of the presumable influence of microbiological processes occurring in areas with dispersed rocks on the engineering-geological properties of the composing rocks has been given in the paper. These problems are urgent for all urbanized territories formed by the massives of dispersed rocks.
Dissertations / Theses on the topic "Geochemical dispersion"
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Ashano, Edafetano Christopher. "The geochemical dispersion associated with mineralisation in the Lake District, North-West England." Thesis, Royal Holloway, University of London, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.265227.
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Bodnar, Matthew Michael. "Modelling geochemical dispersion above a buried polymetallic volcanogenic massive sulphide deposit in a recently glaciated terrain." Thesis, University of British Columbia, 2017. http://hdl.handle.net/2429/64236.
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Modern society requires a resource supply for the continual development of infrastructure
and technology. The discovery of new mineral deposits is challenging as much of North America
is covered by Quaternary sediments that obscure bedrock geology. Enhanced methods in
exploration geochemistry, capable of detecting mineral deposits through complex cover, must be
developed to satisfy global resource demands. Detailed landscape and surficial material mapping over the Lara polymetallic volcanogenic massive sulphide (VMS) deposit were used to establish a landscape evolution model and identify natural processes that govern geochemical responses in shallow soil in glaciated terrain. Upper B horizon soil and physicochemical property measurements were collected along four transects over the deposit and host-rocks and was analyzed by aqua regia ICP-MS/AES, fpXRF and magnetic susceptibility. Select samples were analyzed by sequential extraction and/or for Cu and Zn isotopes to establish the provenance of geochemical responses. Follow-up Ah horizon soil and western hemlock bark samples from a subset of the grid were analyzed by modified aqua regia ICP-MS to determine the role of biochemical cycling. Passive hydrocarbon collector modules were installed at each B horizon soil sample location. Five surficial material domains including till, alluvium and colluvium were identified representing complex alpine glacial and paraglacial processes. Most recent glacial ice flow was valley controlled and sub-parallel to the strike of VMS mineralization as well as a 1-2 m wide pyrite-chalcopyrite stringer zone that occurs 150 m north of the VMS. The highest Zn response occurs over the Lara VMS; however, Cr, Ni, Co and Sc content and magnetic susceptibility indicate this is due to elevated gabbroic content in the till matrix. A response of Zn, Cu, Cd, Mo, Se, Hg, and Te occur over the pyrite zone. Copper isotopes and sequential extraction indicate that geochemical responses are attributed to a clastic source. Zinc, copper, and cadmium in Ah soil and tree bark is controlled by surficial material and geomorphology. Geochemical responses in B horizon soil above the VMS and pyrite zone is interpreted to be caused clastic dispersion of mineralization and mafic host-rocks by glacial transport with negligible input by biochemical cycling.Science, Faculty of
Earth, Ocean and Atmospheric Sciences, Department of
Graduate
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Kelly, Susan. "Geochemical dispersion and concentration of Pb and Zn in soils of the northern Midlands of Ireland." Thesis, Queen's University Belfast, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.343030.
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Theander, Astrid. "Mapping of contaminant dispersion from a polluted mining area by geochemical and geophysical methods, Rävlidmyran,northern Sweden : Use of geochemical and geophysical studies to investigate contaminants." Thesis, Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-73634.
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After open pit mining, the pit can either be backfilled or be filled with groundwater andbecome a pit lake. These lakes tend to be acidic and contains high concentrations ofmetals, which increases the environmental risks in the area. One of these pit lakes isRävlidmyran in the Skellefte ore district. This problem and this pit lake have created thepurpose of this thesis, which is to compare the different water types connected to an openpit, i.e. groundwater, surface water and the actual pit lake water, and to connect the waterwith geophysical readings. The purpose is also to compare ratios between elements to beable to gain more geochemical information.To gain information about the groundwater, several groundwater pipes have since a longtime back been installed in the area. The groundwater has thereafter regularly beensampled and analysed. The surface water has also been sampled regularly in differentspots. In the pit lake, a depth profile has been created by water sampling at differentdepths in the pit lake. The geophysical measurements used in this thesis are resistivityand induced potential measurements, and measurements were done with the slingrammethod.The water sampling indicated that all three types of water contained elevatedconcentrations of metals. The ratio between (Cu+Zn+Pb)/Na indicated that the pit lakehad the highest value. The measurement also indicated that the highest concentration ofdissolved metals is found under the chemocline in the pit lake, compared with other watertypes. Also, the ratio Fe/S were the highest under the chemocline in the pit lake, whichindicates e.g. dissolution of pyrite. When it comes to the ratio representing e.g. dissolutionof gypsum (Ca/S) it was below 1 all the time, except for in two groundwater pipes. The(Ca+Mg)/Na–ratio had the highest values in the pit lake and that indicates dissolution ofe.g. carbonates. This is not very surprising since the pit lake has been and are limedregularly.The geophysical investigations indicated increased electrical conductivity in a waste rockheap northwest of the pit lake, where the sampling indicated elevated copperconcentrations. The readings also show that the groundwater flow direction is againstLake Hornträsket north of the pit lake. They also indicated potential flow paths for thegroundwater. These can contain elevated concentrations of ore elements, which can beconfirmed by a sampling of the groundwater in that area. From the geophysical data, it isalso possible to see that one of the profiles are located along a possible groundwaterplume, based on a low resistivity area and the shape of the potential plume.Efter brytning ur ett dagbrott, så kan dagbrotten ur efterbehandlingssyfte till exempel bliåterfyllt med antingen gråberg eller med vatten. Ifall dagbrottet blir återfyllt med vattenoch en dagbrottssjö skapas, så tenderar denna sjö att vara försurad och innehålla förhöjdahalter av metaller. Detta ökar de lokala belastningarna på miljön i området. En av dessadagbrottssjöar är Rävlidmyran som ligger i Skelleftefältet. Denna dagbrottssjö och dessbieffekter har skapat syftet med detta examensarbete, vilket är att jämföra olikavattentyper kopplade till Rävlidmyran (grundvatten, ytvatten och vatten i dagbrottssjön)samt att jämföra geokemin med geofysiska mätningar. Syftet är också att jämföramolkvoter mellan relevanta element för att i sin tur få mer geokemisk information.För att få fram mer information om grundvatten så har flertalet grundvattenrörinstallerats i området sen flera år tillbaka. Därefter har grundvattnet provtagits ochanalyserats regelbundet. Ytvattnet i området har också provtagits. I dagbrottssjön har enprofil tagits fram genom att ta vattenprover på olika djup i sjön. De geofysiskamätningarna som gjorts är resistivitet och inducerad potential mätningar, samtmätningar som utförts med slingram-metoden.Vattenprovtagningarna indikerade att alla tre vattentyper innehåller förhöjda halter avmetaller. Molkvoten (Cu+Zn+Pb)/Na visade att kvoten var högst under kemoklinen idagbrottssjön i jämförelse med de andra två vattentyperna. De kemiska analyserna avvattenproverna av de olika vattentyperna pekade också på att vattnet under kemoklineni dagbrottssjön innehöll en större mängd lösta joner. Kvoten Fe/S var också högst i dettavatten. När det kommer till molkvoten som bland annat representerar gipsutfällning ochgipsupplösning – Ca/S – så var det under 1 i hela området, med undantag för tvågrundvattenrör. Kvoten (Ca+Mg)/Na var högst i dagbrottssjön och det indikerarupplösning av exempelvis karbonater. Detta är inte helt oväntat, då dagbrottssjön kalkatsregelbundet sedan en lång tid tillbaka.De geofysiska utredningarna indikerade på förhöjd elektrisk konduktivitet i ettgråbergsupplag nordväst om dagbrottssjön, där vattenanalyserna påvisade en förhöjdkoncentration av koppar. Mätningarna visade även att grundvattnets riktning var motsjön Hornträsket, som är lokaliserad norr om dagbrottssjön. De indikerade ävenpotentiella flödesvägar för grundvatten. Dessa flödesvägar kan innehålla förhöjda halterav metaller, vilket kan bekräftas med hjälp av provtagningar av grundvatten i området.Från de geofysiska mätningarna är det också möjligt att se att en av profilerna är placeradlängs med en möjlig grundvattenplym, baserat på en låg resistivitet och den potentiellaplymens form.
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Nkomo, Nomagugu. "The nature of geochemical anomalies associated with the PGE mineralization in the Stella layered intrusion, North West province, South Africa." University of the Western Cape, 2020. http://hdl.handle.net/11394/7713.
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Masters of ScienceThe redistribution patterns of trace elements related to ore mineralisation in the secondary environment are the foundation of regolith exploration geochemistry. Understanding the controls of these element patterns is important for the detection of underlying ore deposits, especially in areas where bedrock is concealed by extensive regolith. The study area, which hosts PGE and gold deposits within the Stella Layered Intrusion is one such area. A major aim of this study was to use major element data to characterise the regolith materials enclosing the PGE mineralisation in the Stella Layered Intrusion to ascertain the degree of weathering that has occurred. Furthermore, the study aimed to relate the weathering patterns in regolith to the distribution of pathfinder elements of PGEs and gold in areas proximal and distal to the mineralised zones. The study was conducted using XRF data, which included major oxide and trace element data. These data were used to characterise regolith materials (scatter plots, K/Al versus Mg/Al plots) and calculating indices that determine the degree of weathering such as CIA and ICV indices as well as A-CN-K and A-CN-FM diagrams. Signatures of pathfinder/ trace elements were enhanced by hydroxylamine hydrochloride partial selective leach technique. The distribution patterns of the partial leach data were compared to the intensity of weathering and weathering products, e.g. manganese oxides, carbonates in areas proximal and distal to the ore zone. In the Serpens North Prospect, the major horizons that were identified include saprolith, stone line and aeolian sands. Incipient calcrete formation occurs in some parts of the Sirius Prospect, while in some parts, well developed, thick calcrete layers are found interlayered with the saprolith and aeolian sand.
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West, Steven. "Geochemical and palynological signals for palaeoenvironmental change in south west England." Thesis, University of Plymouth, 1997. http://hdl.handle.net/10026.1/2156.
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This thesis evaluates the utility of a geochemical technique for the investigation of palaeoenvironmental change in south west England. The method, EDMA (Energy Dispersive X-ray Micro Analysis), is a rapid, non-destructive analysis tool, capable of detecting a large range of geochemical elements. This research examines the most appropriate method of sample preparation for organic soils and peats, and investigates the reliability of results gained from EDMA with respect to conventional bulk geochemical techniques. A detailed study focused on a range of different sedimentary sites in south west England where a variety of palaeoenvironmental changes were thought to occur. Pollen analysis was undertaken on the same sedimentary material, and provided complementary information on the nature and scale of vegetation change through time. Sediments from a coastal valley mire near North Sands, Salcombe, revealed information relating to the processes of sea-level change in this part of south Devon and the subsequent autogenic processes as the sediment accumulated through time. A range of sites were located on the granitic upland of Dartmoor. A raised bog, Tor Royal, provided data relating to the changing nature of the central upland landscape from late Mesolithic times to the present day. Two soligenous sites, Upper Merrivale and Piles Copse, sought to investigate the activities of postulated anthropogenic activity at a much smaller spatial scale, with particular interest placed upon the evidence for deforestation activity and the utilisation of the local mineral resources. The last site, Crift Down, a lowland spring fed valley mire utilised geochemical and palynological fluxes within the peat to investigate processes and activities associated with archaeological evidence for Medieval tinworking in this area of Cornwall. The results from the EDMA investigations, and comparable studies using other geochemical methods including EMMA, AAS and flame photometry, suggest the technique to have greatest applicability as a first stage tool in the analysis of general activities of past environmental change. The technique was found to yield reliable results for the major elements (Si, Al, 5, Fe, Ca, K, Na and Mg), but is generally incapable of providing useful data on heavy metal elements. The data from south west England suggest the method to reflect activity at a range of different scales, and as part of a structured programme of analysis may contribute information to allow a more holistic environmental reconstruction to be made.
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Hill, Leanne Jodie. "Geochemical and biogeochemical dispersion and residence in landscapes of western New South Wales." Phd thesis, 2004. http://hdl.handle.net/1885/148590.
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Khider, Kamal. "Regional geochemical dispersion of elements in the regolith of the Girilambone Region, Central West NSW." Phd thesis, 2007. http://hdl.handle.net/1885/147119.
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Mitchell, Charlotte. "Lateral and Vertical Geochemical Dispersion into Deep Cover: 4D Landscape Geochemistry and Biogeochemistry of the Barrier Ranges." Thesis, 2017. http://hdl.handle.net/2440/119328.
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The aim of this thesis is to determine the relative contribution of lateral, as opposed to vertical, dispersion of the geochemical signals of basement-hosted mineralisation in prospective geological provinces that are mantled by transported cover. The study focuses on three areas within and on the margins of, the highly-mineralised Broken Hill Block and the Barrier Ranges in western New South Wales. Fowlers Creek overlies low-grade metasedimentary bedrock with no known mineralisation on the eastern margins of the Barrier Ranges. Stream sediments show a downstream decreasing trend in concentrations in both Pb and Zn with values decreasing by 50% over 7 km of creek. Lead and Ag values were less important along Fowlers Creek in terms of biogeochemical results, with concentrations at background levels Pb 0.27 ppm and Ag 3.04 ppb. Rather, elements of interest along Fowlers Creek included; Cs, Y, U, Co and Ni. These elements peaked at 2 distinct points along the creek, by an order of magnitude above background, at points where the local geology interrupts the flow of the stream base aquifer (SBA). Pine Creek cross-cuts the partially exposed Pinnacles Pb-Zn-Ag mine. Stream sediment samples contain elevated concentrations of Pb, Zn and Ag (Pb 4.5x and Ag 3.5x background values observed along Fowlers and Umberumberka Creeks) for at least 4.5 km downstream of mineralisation. River red gum (RRG) leaves from trees within the creek provided the clearest delineation of the underlying mineralisation. Lead and Ag concentrations steadily increase toward mineralisation and reach concentrations 2.5 orders of magnitude above background immediately above mineralisation. Leaf samples collected after a severe El Niño event where the previous year’s rainfall was 188 mm, had Pb and Ag concentrations 5 -10 times greater than samples from the same trees collected after a La Niña event where the previous year’s rainfall was 605 mm. These results demonstrate that changes in available water plays on the SBA and the significant role it plays in diluting the resulting metal concentration within the trees and the importance of temporal variation. Umberumberka Creek is underlain by high-grade metamorphic rocks with numerous small mineral occurrences. Umberumberka Creek discharges at the western margin of the Broken Hill Block as an alluvial fan system which extends at least 10 km onto the Mundi Mundi Plain. This area is underlain by prospective bedrock but is buried by up to 150 m of transported sediments. On the plains, stream sediment results reflected a catchment average that was carried 10 km onto the plains before values decreased. Silver results on the plains had a mean value of 30 ppb and are comparable to soil survey results obtained by an exploration company over an area of Pb-Ag-Zn mineralisation identified beneath 150+ m of cover, situated on the fan floodout boundaries of Umberumberka Creek. The biogeochemical results for Umberumberka Creek fall within the same range of values as Fowlers creek, suggesting that these values are the natural background range for RRG. Results from both the stream sediments and the RRG suggest that the soil survey results obtained on the plains most likely reflect lateral dispersion from the Broken Hill Block rather than a vertical signal from below. For the Broken Hill Block lateral dispersion is kilometric (at least 10 km) in creeks and distributive depositional systems. The signal is diluted due to catchment averaging but can still be elevated above background thus obscuring potential vertically transported signal from bedrock. The RRG provide a mechanism to see vertically down to the basement at depths of 10s of meters (Pine Creek and to an extent along Fowlers Creek) but don’t give a signal when the depth to the source is 100s of meters. For the exploration industry to be successful in areas of thick transported cover it becomes ever more important to step back from there anomalies and see where they sit within the bigger landscape picture and temporally within the exploration programThesis (Ph.D.) -- University of Adelaide, School of Physical Sciences, 2017
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Netshiongolwe, Khathutshelo Emmanuel. "Geochemical characterisation of gold tailings footprints on the Central Rand Goldfield." Diss., 2018. http://hdl.handle.net/10500/24068.
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Gold mining in the Witwatersrand Basin of South Africa has resulted in soil contamination due to the lack of sufficient environmental management plans for the tailings dumps and remnant footprints. Tailings reclamation as a strategy of reducing pollution in the Central Rand, for instance, has resulted in contamination of water systems by acid mine drainage (AMD). After removal of the tailings dumps, remnant material is left over on the tailings footprints and these contain significant amounts of pollutants that were initially in the tailings. Heavy rainfall during summer dissolves primary minerals and later in the dry season, secondary minerals are precipitated as efflorescent crusts on and nearby tailings dumps as well as footprints due to high evaporation. The efflorescent crusts can redissolve when it rains and form acidic, metal and sulphate-rich solutions due to their soluble characteristics.
This study aimed to characterise tailings footprints in areas targeted for human settlements and office spaces to assess their potential to release left over toxic elements such arsenic (As), lead (Pb), copper (Cu) and zinc (Zn). The approach to the study involved characterisation of oxidised and unoxidised tailings material and secondary precipitates on both tailings dumps and footprints. This involved determining the mineralogical composition using Powder X-ray Diffraction (PXRD). Dissolution and leaching studies were also conducted on the material followed by determination of constituent elements using inductively coupled plasma optical emission spectroscopy (ICP-OES) and sulphates using ion chromatography (IC). The leaching solutions used included rainwater; dilute sulphuric acid at pH of 3.0 (a common leachate in such acidic soils); as well as plant exudates such as oxalic and citric acids.
The leachate solutions were used to correlate the mineralogical composition of secondary precipitates and tailings footprints. Potential implications on humans following any accidental ingestion of the tailings or contaminated soils were assessed using gastric juices. The ecological risk factors and risk index together with the model to evaluate daily intake and different pathways to humans were used to assess the toxicity caused by exposure to contaminants in the materials. The experimental work was augmented by computer simulations based on geochemical modelling (using the PHREEQC geochemical modelling code) to determine the speciation of elements (and thus their potential lability and bioavailability), dissolution and formation of secondary mineral precipitates in the tailings dumps and footprints. The findings of the PXRD study showed that the mineralogy of the tailings and footprints was dominated by quartz (SiO2) and some minor minerals such as pyrite (FeS2), pyrophyllite (Al2Si4O10(OH)2), chlorite (Mg,Fe)3(Si,Al)4O10), mica (K(Mg,Fe)3 AlSi3O10(F,OH)2) while that of secondary precipitates was dominated by jarosite (KFe3+ 3(OH)6 (SO4)2), goethite (FeOOH), melanterite (FeSO4.7H2O) and gypsum (CaSO4.2H2O). Minerals obtained for the secondary precipitates were corroborated by geochemical modelling.
Leaching results using rainwater with pH ranges from 3.5 to 3.9 showed that trace elements are released very slowly from tailings dumps and footprints and in small concentrations during rainy seasons as follows: As (1.5 mg/L-4.5 mg/L), Pb (3.5 mg/L-5.5 mg/L), Cu (4 mg/L-4.8 mg/L) and Zn (23 mg/L-44 mg/L). The release and mobility of Cu, Pb, Zn and As occurs quite markedly when secondary precipitates dissolve, making the immediate impacted environment unfavourable for plant growth and any habits in the vicinity. This was substantiated by simulated dissolutions and assessment of the resulting elemental speciation that pointed to the elements being distributed in bioavailable forms, implying potential uptake by plants (such as vegetables that may be cultivated on such impacted soils).
The model was used to evaluate the daily intake and different exposure pathways and the results showed that children may daily intake 48.4 mg kg-1 day-1 and adults‟ 32.8 mg kg-1 day-1 . After 5 years (1825 days) of exposure more harm may be experienced and findings shows that kids are the most victims on these contaminated sites compared to adults. Both children and adults may absorb low levels of these toxic elements daily and after long time of exposure it may cause disease like cancer in their body which may lead to death. Pathways may be through inhalation and accidentally ingesting tailings soil that contain toxic elements. Drawing from the above findings, it will be important that tailings footprints that have been earmarked as land for development (residential or office space) be thoroughly assessed for potential release of toxic elements and high levels of acidity. Further reclamation aimed at reducing these hazards can then be implemented.College of Agriculture and Environmental Sciences
M. Sc. (Environmental Science)
Books on the topic "Geochemical dispersion"
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Nielsen, E. Glacial dispersion and till geochemistry around the Lar Cu-Zn deposit, Lynn Lake Greenstone Belt, Manitoba. Winnipeg: Manitoba Energy and Mines, Geological Services, 1991.
Find full textBook chapters on the topic "Geochemical dispersion"
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Mkandawire, Martin. "Geochemical Prediction of Metal Dispersion in Surface and Groundwater Systems." In Nano and Bio-Based Technologies for Wastewater Treatment, 1–40. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2019. http://dx.doi.org/10.1002/9781119577119.ch1.
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Buffoni, G., A. Griffa, and E. Zambianchi. "Modelling of dispersion processes in a tide-forced flow." In Biological, Physical and Geochemical Features of Enclosed and Semi-enclosed Marine Systems, 19–24. Dordrecht: Springer Netherlands, 1999. http://dx.doi.org/10.1007/978-94-017-0912-5_3.
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Zhou, Di. "Statistical Analysis of Dispersion and Geochemical Patterns of Sedimentary System in Northern Shelf of the South China Sea." In Computerized Modeling of Sedimentary Systems, 401–12. Berlin, Heidelberg: Springer Berlin Heidelberg, 1999. http://dx.doi.org/10.1007/978-3-662-03902-1_21.
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Getchell, Amy, Hailie Swanson, and Marika Santagata. "Geochemical Control of Laponite Dispersions for Pore Fluid Engineering of Granular Soils." In Trends in Mathematics, 135–45. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-99474-1_14.
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"Geochemical Dispersion in the Secondary Environment." In Regolith Exploration Geochemistry in Arctic and Temperate Terrains, 93–125. Elsevier, 1992. http://dx.doi.org/10.1016/b978-0-444-89154-9.50011-8.
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Putikov, O. F., and B. Wen. "Chapter 2 Geoelectrochemistry and stream dispersion." In Geochemical Remote Sensing of the Sub-surface, 17–79. Elsevier, 2000. http://dx.doi.org/10.1016/s0168-6275(00)80026-4.
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Butt, C. R. M., and H. Zeegers. "Climate, Geomorphological Environment and Geochemical Dispersion Models." In Regolith Exploration Geochemistry in Tropical and Subtropical Terrains - Handbook of Exploration Geochemistry, 3–24. Elsevier, 1992. http://dx.doi.org/10.1016/b978-0-444-89095-5.50008-0.
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Luis Manrique Carreño, John. "Geochemistry Applied to the Exploration of Mineral Deposits." In Geochemistry [Working Title]. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.103941.
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Geochemistry can be applied to the exploration of mineral deposits, for which it is necessary to understand the fundamentals of geochemical prospecting, the geochemical dispersion of elements based on their chemical properties. This chapter presents the basics of geochemical prospecting including: element mobility depending on ionic potential, pH, and Eh, with examples of Cu mobility during supergenic alteration of a primary sulfide deposit, a brief overview of sampling/geochemical prospecting methods, as well as a case study of the geochemical prospecting study carried out in the vanadium (V), uranium (U), and zinc (Zn) sedimentary mineral deposit of Puyango, Ecuador, in which anomalous and subanomalous values were detected in rock samples of various pathfinder elements of V and U.
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Zhang, M. "Chapter 4 Carbon dioxide dispersion halos around mineral deposits." In Geochemical Remote Sensing of the Sub-surface, 123–32. Elsevier, 2000. http://dx.doi.org/10.1016/s0168-6275(00)80028-8.
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Wackernagel, Hans, and Henri Sanguinetti. "Gold Prospecting With Factorial Cokriging In The Limousin, France." In Computers in Geology - 25 Years of Progress. Oxford University Press, 1994. http://dx.doi.org/10.1093/oso/9780195085938.003.0008.
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In geochemical prospecting for gold a major difficulty is that many values are below the chemical detection limit. Tracers for gold thus play an important role in the evaluation of multivariate geochemical data. In this case study we apply geostatistical methods presented in Wackernagel (1988) to multielement exploration data from a prospect near Limoges, France. The analysis relies upon a metallogenetic model by Bonnemaison and Marcoux (1987, 1990) describing auriferous mineralization in shear zones of the Limousin. The aim of geochemical exploration is to find deposits of raw materials. What is a deposit? It is a geological anomaly which has a significant average content of a given raw material and enough spatial extension to have economic value. The geological body denned by an anomaly is generally buried at a specific depth and may be detectable at the surface through indices. These indices, which we shall call superficial anomalies, are disposed in three manners: at isolated locations, along faults, and as dispersion halos. These two definitions of the word "anomaly" correspond to a vision of the geological phenomenon in its full continuity. Yet in exploration geochemistry only a discrete perception of the phenomenon is possible through samples taken along a regularly meshed grid. A superficial anomaly thus can be apprehended by one or several samples or it can escape the grip of the geochemist when it is located between the nodes of the mesh. A geochemical anomaly, in the strict sense, only exists at the nodes of the sampling grid and we shall distinguish between: a pointwise anomaly defined on a single sample, and a groupwise anomaly defined on several neighboring samples. This distinction is important both upstream, for the geological interpretation of geochemical measurements, and downstream, at the level of geostatistical manipulation of the data. It will condition an exploration strategy on the basis of the data representations used in this case study. A pointwise anomaly, i.e., a high, isolated value of the material being sought, will correspond either to a geological phenomenon of limited extent or to a well hidden deposit.
Conference papers on the topic "Geochemical dispersion"
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Blinov, A. V., A. E. Budyak, Yu I. Tarasova, I. V. Papkin, V. O. Ilchenko, and A. A. Nikulina. "Comparative Evaluation of Geochemical Methods of Searches for Secondary Dispersion Halos in Complex Landscape-Geochemical Conditions of Eastern Transbaikal." In Engineering and Mining Geophysics 2021. European Association of Geoscientists & Engineers, 2021. http://dx.doi.org/10.3997/2214-4609.202152132.
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Sánchez-Murillo, Ricardo. "Hydrogeological responses in tropical mountainous springs." In I Congreso Internacional de Ciencias Exactas y Naturales. Universidad Nacional, 2019. http://dx.doi.org/10.15359/cicen.1.37.
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This study presents a hydrogeochemical analysis of spring responses (2013-2017) in the tropical mountainous region of the Central Valley of Costa Rica. The isotopic distribution of δ18O and δ2H in rainfall resulted in a highly significant meteoric water line: δ2H = 7.93×δ18O + 10.37 (r2=0.97). Rainfall isotope composition exhibited a strong dependent seasonality. The isotopic variation (δ18O) of two springs within the Barva aquifer was simulated using the FlowPC program to determine mean transit times (MTTs). Exponential-piston and dispersion distribution functions provided the best-fit to the observed isotopic composition at Flores and Sacramento springs, respectively. MTTs corresponded to 1.23±0.03 (Sacramento) and 1.42±0.04 (Flores) years. The greater MTT was represented by a homogeneous geochemical composition at Flores, whereas the smaller MTT at Sacramento is reflected in a more variable geochemical response. The results may be used to enhance modelling efforts in central Costa Rica, whereby scarcity of long-term data limits water resources management plans.
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Johnson, Andrew C., Jeffrey Miles, Laurent Mosse, Robert Laronga, Violeta Lujan, Niranjan Aryal, and Dozie Nwosu. "INTEGRATING A NOVEL CHLORINE MEASUREMENT WITH RESISTIVITY, DIELECTRIC DISPERSION, AND 2D NMR TO RESOLVE SALINITY AMBIGUITY: CASE STUDIES IN ORGANIC SHALE FORMATIONS." In 2021 SPWLA 62nd Annual Logging Symposium Online. Society of Petrophysicists and Well Log Analysts, 2021. http://dx.doi.org/10.30632/spwla-2021-0077.
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Formation water saturation is a critical target property for any comprehensive well log analysis program. Most techniques for computing saturation depend heavily on an analyst’s ability to accurately model resistivity measurements for the effects of formation water resistivity and rock texture. However, the pre-requisite knowledge of formation water properties, particularly salinity, is often either unknown, varying with depth or lateral extent, or is difficult to derive from traditional methods. A high degree of variability may be present due to fluid migration from production, water injection, or various geological mechanisms. In unconventional reservoirs, the complexity of the rocks and pore structure further complicates traditional interpretation of the available well logs. These factors introduce significant uncertainties in the computed fluid saturations and therefore can substantially affect final reserves estimates. A novel technique in geochemical spectroscopy has recently been introduced to distinguish the chlorine signals of the formation and borehole. The new, quantitative measurement of formation chlorine enables a direct calculation of bulk water volume for a given formation water salinity. When integrated into a multi-physics log analysis workflow, the chlorine-derived water volume can provide critical information on fluid saturations, hydrocarbon-in-place, and producibility indicators. This additional information is especially useful for characterizing challenging and complex unconventional reservoirs. We present the new technique through several full petrophysical evaluation case studies in organic shale formations across the U.S., including the Midland, Delaware, Marcellus, and DJ basins. We solve for formation-specific water salinity and bulk water volume through an optimization that combines chlorine concentration with resistivity and dielectric measurements. These outputs are integrated into comprehensive petrophysical evaluations, leveraging a suite of advanced well log measurements to compute final fluid and rock properties and volumetrics. The evaluations include geochemical mineralogy logs, 2D NMR analyses, dielectric dispersion analyses, basic log measurements, and multi-mineral models. The results underscore the utility of the new spectroscopy chlorine log to reduce petrophysical model uncertainties in an integrated workflow. While this workflow has been demonstrated here in several U.S. organic shale case studies, the fundamental challenges it addresses will make it a valuable solution for a range of unconventional reservoirs globally.
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Aljaberi, Abdulla, Shokoufeh Aghabozorgi, and Mehran Sohrabi. "A Universal Method for Predicting the Relative Permeability Data of Low Salinity Injection." In SPE EuropEC - Europe Energy Conference featured at the 83rd EAGE Annual Conference & Exhibition. SPE, 2022. http://dx.doi.org/10.2118/209661-ms.
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Abstract Low salinity waterflood (LSWF) injection is an enhanced oil recovery (EOR) method proven effective through extensive experimental studies. Correct implementation of this method in reservoir-scale simulations requires reliable estimation of changes in relative permeability data associated with LSWF. For this purpose, a few models have been suggested based on geochemical interactions, such as the cation exchange capacity of clay, which are case dependent and cannot be applied to all systems. This study presents a novel semi-empirical model based on incremental oil recovery measured during low salinity injection. Therefore, it can be applied to all rock types, fluid systems, and wettability conditions regardless of the active mechanism. Some mechanisms proposed in the literature relate the additional oil recovery during low salinity injection to measurable parameters such as micro-dispersion. As a result, the kr curves can be constructed using this new methodology by measuring the micro-dispersion. This method has been validated against five sets of secondary and tertiary coreflood experiments published in the literature. First, the high salinity kr data is obtained by history matching using the CMOST module of CMG software. Then the proposed method and the measured value of additional oil recovery were used to estimate the kr data of low salinity injection. The results showed that the suggested method could predict the oil recovery and pressure drop in secondary and tertiary modes. The high-salinity relative permeability was shifted towards a more water-wet condition in tertiary mode. The kr curve of secondary LSWF showed a significant shift towards a more water-wet condition than tertiary mode, implying lower residual oil saturation. Since the additional oil recovery versus micro-dispersion curve was reported for this rock sample, one can simply predict the kr values of LSWF for other values of micro-dispersion. Due to the ongoing debate regarding the dominant mechanism during LSWF, there is no universal model for estimating the relative permeability of LSWF in all systems. The model presented in this paper provides a powerful tool for engineers to simulate the LSWF kr data in both tertiary and secondary flooding regardless of the active mechanism.
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Andersen, Pål Østebø, Reidar Inge Korsnes, Andre Tvedt Olsen, and Erik Bukkholm. "Reaction Kinetics Determined from Core Flooding and Steady State Principles for Stevns Klint and Kansas Chalk Injected with MgCl2 Brine at Reservoir Temperature." In SPE Improved Oil Recovery Conference. SPE, 2022. http://dx.doi.org/10.2118/209380-ms.
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Abstract A methodology is presented for determining reaction kinetics from core flooding: A core is flooded with reactive brine at different compositions with injection rates varied systematically. Each combination is performed until steady state, when effluent concentrations no longer change significantly with time. Lower injection rate gives the brine more time to react. We also propose shut-in tests where brine reacts statically with the core a defined period and then is flushed out. The residence time and produced brine composition is compared with the flooding experiments. This design allows characterization of the reaction kinetics from a single core. Efficient modeling and matching of the experiments can be performed as the steady state data are directly comparable to equilibrating the injected brine gradually with time and does not require spatial and temporal modeling of the entire dynamic experiments. Each steady state data point represents different information that helps constrain parameter selection. The reaction kinetics can predict equilibrium states and time needed to reach equilibrium. Accounting for dispersion increases the complexity by needing to find a spatial distribution of coupled solutions and is recommended as a second step when a first estimate of the kinetics has been obtained. It is still much more efficient than simulating the full dynamic experiment. Experiments were performed injecting 0.0445 and 0.219 mol/L MgCl2 into Stevns Klint chalk from Denmark, and Kansas chalk from USA. The reaction kinetics of chalk are important as oil-bearing chalk reservoirs are chemically sensitive to injected seawater. The reactions can alter wettability and weaken rock strength which has implications for reservoir compaction, oil recovery and reservoir management. The temperature was 100 and 130°C (North Sea reservoir temperature). The rates during flooding were varied from 0.25 to 16 PV/d while shut-in tests provided equivalent rates down to 1/28 PV/d. The results showed that Ca2+ ions were produced and Mg2+ ions retained (associated with calcite dissolution and magnesite precipitation, respectively). This occurred in a substitution-like manner, where the gain of Ca was similar to the loss of Mg2+. A simple reaction kinetic model based on this substitution with three independent tuning parameters (rate coefficient, reaction order and equilibrium constant) was implemented together with advection to analytically calculate steady state effluent concentrations when injected composition, injection rate and reaction kinetic parameters were stated. By tuning reaction kinetic parameters, the experimental steady state data could be fitted efficiently. From data trends, the parameters were determined relatively accurate for each core. The roles of reaction parameters, pore velocity and dispersion were illustrated with sensitivity analyses. The steady state method allows computationally efficient matching even with complex reaction kinetics. Using a comprehensive geochemical description in the software PHREEQC, the kinetics of calcite and magnesite mineral reactions were determined by matching the steady state concentration changes as function of (residence) time. The simulator predicted close to identical production of Ca as loss of Mg. The geochemical software predicted much higher calcite solubility in MgCl2 than observed at 100 and 130°C for Stevns Klint and Kansas.
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Deucher, Ricardo H., and Hamdi A. Tchelepi. "High-Order Adaptive Scheme for Reactive Transport in Heterogeneous Porous Media." In SPE Reservoir Simulation Conference. SPE, 2021. http://dx.doi.org/10.2118/203972-ms.
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Abstract Subsurface sequestration of carbon dioxide, contaminant transport, and enhanced oil recovery processes often involve complex reaction dynamics. The rock-fluid interactions span a very wide range of length and time scales, and it is important for the numerical solutions to resolve these scales properly. To address these challenges, we extend the adaptive transport scheme for the simulation of reactive transport in heterogeneous porous media developed previously (Deucher and Tchelepi, 2021) to account for (a) higher-order approximation of the convective fluxes and (b) coupling with a chemical solver connected to geochemical databases. The numerical results demonstrate that adaptivity is more effective when a higher-order approximation of the fluxes is used. This is because of lower levels of numerical dispersion compared with low-order approximations, which helps resolve the displacement fronts more accurately. As a result, the regions that experience significant concentration and saturation gradients are more confined, and that leads to improvements in the computational efficiency of the adaptive scheme. The robustness of the approach is demonstrated using a highly heterogeneous two-phase case with multiple wells and a variable total liquid-rate. Due to the modularity of the adaptive scheme, coupling with a chemical solver module is straightforward. The scheme is tested for a three-dimensional case that considers injection of carbonated water in a reservoir matrix of calcite. The results show that the adaptive scheme leads to an accurate representation of the reference concentration distributions of the six reactive components throughout the simulation and leads to a large reduction in the number of cell updates required to achieve the solution.
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Piestrzyński, Adam, Jadwiga Pieczonka, and Edward Chruściel. "Model for Long-Term Stabilization and Isolation of Low Level Uranium Waste." In ASME 2001 8th International Conference on Radioactive Waste Management and Environmental Remediation. American Society of Mechanical Engineers, 2001. http://dx.doi.org/10.1115/icem2001-1261.
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Abstract Problems arising from uranium dispersion from mines and mine tailings, and the remediation of uranium contaminated areas, are discussed in this paper. In an experimental remediation study, a mixture of 70 vol.% of uraniferous mining wastes and 30 vol.% of a natural ceramic were used. The preliminary observations are discussed, and a model is proposed for the long term stabilization of mining tailings. Observations and monitoring of contaminated sites carried out during the last 25 years have revealed local impacts of uranium on the environment in Lower Silesia, Poland. Uranium pollution is limited to waste dumps, mine tailings, and their close vicinities at Kowary Podgórze, Radoniów, Kopaniec and Kletno. Uranium dispersion takes place mechanically due to transport by river waters, chemically by rain and ground waters, and anthropogenically when the wastes are utilized in construction. Floods are an additional mechanism responsible for the mechanical dispersion of uranium. As a result of these uranium transport mechanisms, in order to minimize the impacts of uranium on the environment, the covering of dumps with non-radioactive material is suitable only for sites located away from populated areas. Redox reactions have been observed at the Kowary tailings. During these reactions, iron hydroxide (goethite), hematite, and gypsum, are precipitated as solids. These observations provide a good prognosis for the long-term stabilization of radionuclides which can be incorporated into proposals for the construction of tailings sites. Using Eh-pH diagrams (system U-C-O-H, 25°C, 1 bar), UO2 is stable over the whole range of naturally occurring pHs, and is affected by Eh only in the range −0.4 to +0.1 volts in acidic environments, and below −0.4v in basal environments. BaSO4 and RaSO4 are stable under almost the same conditions as UO2. An environmentally significant redox boundary (FeS2 versus Fe2O3) occurs in the middle of the UO2 stability field. The geochemical and environmental behaviour of the elements discussed above suggest a mechanism for stabilizing radionuclides within stored wastes. The solidification of wastes should occur concurrently with naturally occurring redox reactions. During oxidation, an active iron-hydroxide gel is produced. This gel is then dehydrated and converted into limonite (a mixed compound), a monohydrate (goethite), hydro-hematite (Fe2O3·1/2H2O) and hematite (Fe2O3). This reaction occurs in neutral or weakly acidic environments. A key problem in the proposed remediation project, therefore, is pH stabilization in order to maintain the required environment for oxidation and cementation reactions. In order to achieve such an environment and to stabilize the reactions, a construction method is proposed for new waste storage systems, based on mixed layers of waste and barrier components composed of natural materials. The presence of CaO or Ca(OH)2 and anhydrite in the proposed internal membrane will reduce the vertical migration of sulphates. Redox reactions will be responsible for the secondary precipitation (reduction) of uranyl. These same reactions occur naturally during the precipitation of uranium ores. Iron oxidation is the other process in the redox pair required to reduce [UO2]+2 to UO2. The resultant pitchblende is insoluble in normal oxidizing environments. To minimize the dissolution of UO2 by sulphuric acid generated during the iron oxidation reaction, the construction of pH active membranes containing calcium oxide or hydroxide are recommended. These compounds will react with the free acid to precipitate gypsum. Although several elements can be mobilized as a result of oxidation, radium remains in insoluble solid phases such as the common Ca, Ba and Sr sulphates.
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Tiwari, Pankaj Kumar, Prasanna Chidambaram, Ahmad Ismail Azahree, Debasis Priyadarshan Das, Parimal Arjun Patil, Zoann Low, Prasanna Kumar Chandran, Raj Deo Tewari, M. Khaidhir Abdul Hamid, and M. Azriyuddin Yaakub. "Safeguarding CO2 Storage in a Depleted Offshore Gas Field with Adaptive Approach of Monitoring, Measurement and Verification MMV." In SPE Middle East Oil & Gas Show and Conference. SPE, 2021. http://dx.doi.org/10.2118/204590-ms.
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Abstract CO2 sequestration is a process for eternity with a possibility of zero-degree failure. One of the key components of the CO2 Sequestration Project is to have a site-specific, risk-based and adaptive Monitoring, Measurement and Verification (MMV) plan. The storage site has been studied thoroughly and is understood to be inherently safe for CO2 sequestration. However, it is incumbent on operator to manage and minimize storage risks. MMV planning is critical along with geological site selection, transportation and storage process. Geological evaluation study of the storage site suggests the containment capacity of identified large depleted gas reservoirs as well as long term conformance due to thick interval. The fault-seal analysis and reservoir integrity study contemplate long-term security of the CO2 storage. An integrated 3D reservoir dynamic simulation model coupled with geomechanical and geochemical models were performed. This helps in understanding storage capacity, trapping mechanisms, reservoir integrity, plume migration path, and injectivity. To demonstrate that CO2 plume migration can be mapped from the seismic, a 4D Seismic feasibility study was carried out using well and fluid data. Gassmann fluid substitution was performed in carbonate reservoir at well, and seismic response of several combination of fluid saturation scenarios on synthetic gathers were analyzed. The CO2 dispersion study, which incorporate integration of subsurface, geomatic and metocean & environment data along with leakage character information, was carried out to understand the potential leakage pathway along existing wells and faults which enable to design a monitoring plan accordingly. The monitoring of wells & reservoir integrity, overburden integrity will be carried out by Fiber Optic System to be installed in injection wells. Significant difference in seismic amplitude observed at the reservoir top during 4D seismic feasibility study for varying CO2 saturation suggests that monitoring of CO2 plume migration from seismic is possible. CO2 plume front with as low as 25% saturation can be discriminated provided seismic data has high signal noise ratio (SNR). 3D DAS-VSP acquisition modeling results show that a subsurface coverage of approximately 3 km2 per well is achievable. Laboratory injectivity studies and three-way coupled modelling simulations established that three injection wells will be required to achieve the target injection rate. As planned injection wells are field centric and storage site area is large, DAS-VSP find limited coverage to monitor the CO2 plume front. Hence, surface seismic acquisition will be an integral component of full field monitoring and time-lapsed evaluations for integrated MMV planning to monitor CO2 plume migration. The integrated MMV planning is designed to ensure that injected CO2 in the reservoir is intact and safely stored for hundreds of years after injection. Field specific MMV technologies for CO2 plume migration with proactive approach were identified after exercising pre-defined screening criteria.
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Al-Muraikhi, Rasha, Nami Mohammad Al-Mutairi, Karim Ousdidene, Caroline Magnier, Sachin Sharma, and Hakim Benyounes. "Using XRF Elemental Data and XRD Direct Measured Mineralogy for an Accurate Wellbore Placement and Geosteering through Carbonates Reservoirs* Drilled Within 04 ½" Slim Hole: A Case Study from a Jurassic Middle Marrat Carbonates Reservoir-Kuwait." In SPE Annual Technical Conference and Exhibition. SPE, 2021. http://dx.doi.org/10.2118/206328-ms.
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ABSTRACT As the pursuit of oil and gas in Middle East Jurassic carbonates reservoirs grows, it is increasingly evident that horizontal wellbore placement, or targeting, plays a first-order role in the production capability of a well. Indeed, the percentage of a wellbore "in target" is a common metric used when evaluating the causes for good or poor production from any particular well. The most common process used for geosteering a horizontal wellbore into a chosen target is the correlation of logging-while-drilling (LWD) total gamma-ray (GR) to a vertical pilot-hole GR log or offset wells GR logs. However, limitations inherent to this procedure can reduce the ability to effectively use LWD GR data due to 4 ½" slim hole diameter and mud telemetry issues, the non-descript signal from LWD tools due to high pressure and high temperature and the possibility of lost signal from LWD tools. In addition, the thickness of MRW-F11 targeted reservoir is limited to plus or minus 22 ft and low GR contrast from bed to bed might lead to loss of directional control in the target MRW-F11. To accurately geosteer a well, Geochemical analyses of drilled cuttings are proposed to assist well placement. The analyses performed were elemental data derived from energy-dispersive X-ray fluorescence (ED-XRF) and mineralogical quantitative content acquired from the direct measurement from energy-dispersive X-ray Diffraction (ED-XRD). The Elemental and mineralogy data were acquired from drilling cuttings taken at ten feet intervals, from two offsets wells. The mineral and elemental data were used to build a chemo-stratigraphic profile and zonation of the sedimentary section. Chemo-stratigraphic zones are defined as having multiple elements and keys ratios (where possible) which illustrate distinct changes in chemical and mineralogical composition profiles from one zone to another. These zones were correlated over reasonable distances (at a minimum the length of the horizontal wellbore) and can be readily identifiable in cuttings. Using these criteria chemo-stratigraphic zonation's have been constructed in the Middle Marrat formation going from MRW-F1 toward MRW-F11 layer. Well site ED-XRF and ED-XRD data were used in conjunction with LWD Gamma Ray to geosteer at approximately 22 feet thin zone which resides at the base of an approximately 100 ft thick reservoir carbonate section of the main MRW-F11 reservoir. The LWD GR Signal was 45 ft behind the bit while all XRF and XRD data were at plus or minus 5 feet while sliding at plus or minus 10 ft in rotary mode and with a controlled slow rate of penetration (ROP) of 10 ft/hr. Geochemical rock analyses (GEAR) using XRF & XRD chemical analyses was the unique reference for approximately 500 ft interval to geosteer the well when LWD lost the signal, wiper trip was cancelled which considerably reduced drilling costs. Well site XRF and XRD data was successfully applied to geosteer the well, determine the position of the wellbore in zones of non-descript LWD GR signature, and determine the lateral extent of the reservoir interval.
Reports on the topic "Geochemical dispersion"
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Helgeson, H. C. Advective diffusive/dispersive transport in geochemical processes. Office of Scientific and Technical Information (OSTI), May 1991. http://dx.doi.org/10.2172/5717404.
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Mohammadi, N., D. Corrigan, A. A. Sappin, and N. Rayner. Evidence for a Neoarchean to earliest-Paleoproterozoic mantle metasomatic event prior to formation of the Mesoproterozoic-age Strange Lake REE deposit, Newfoundland and Labrador, and Quebec, Canada. Natural Resources Canada/CMSS/Information Management, 2022. http://dx.doi.org/10.4095/330866.
Full textAbstract:
A complete suite of bulk major- and trace-elements measurements combined with macroscopic/microscopic observations and mineralogy guided by scanning electron microscope-energy dispersive spectrometry (SEM-EDS) analyses were applied on Nekuashu (2.55 Ga) and Pelland (2.32 Ga) intrusions in northern Canada, near the Strange Lake rare earth elements (REE) deposit, to evaluate their magmatic evolution and possible relations to the Mesoproterozoic Strange Lake Peralkaline Complex (SLPC). These Neoarchean to earliest-Paleoproterozoic intrusions, part of the Core Zone in southeastern Churchill Province, comprise mainly hypersolvus suites, including hornblendite, gabbro, monzogabbro/monzodiorite, monzonite, syenite/augite-syenite, granodiorite, and mafic diabase/dyke. However, the linkage of the suites and their petrogenesis are poorly understood. Geochemical evidence suggests a combination of 'intra-crustal multi-stage differentiation', mainly controlled by fractional crystallization (to generate mafic to felsic suites), and 'accumulation' (to form hornblendite suite) was involved in the evolution history of this system. Our model proposes that hornblendite and mafic to felsic intrusive rocks of both intrusions share a similar basaltic parent magma, generated from melting of a hydrous metasomatized mantle source that triggered an initial REE and incompatible element enrichment that prepared the ground for the subsequent enrichment in the SLPC. Geochemical signature of the hornblendite suite is consistent with a cumulate origin and its formation during the early stages of the magma evolution, however, the remaining suites were mainly controlled by 'continued fractional crystallization' processes, producing more evolved suites: gabbronorite/hornblende-gabbro ? monzogabbro/monzodiorite ? monzonite ? syenite/augite-syenite. In this proposed model, the hydrous mantle-derived basaltic magma was partly solidified to form the mafic suites (gabbronorite/hornblende-gabbro) by early-stage plagioclase-pyroxene-amphibole fractionation in the deep crust while settling of the early crystallized hornblende (+pyroxene) led to the formation of the hornblendite cumulates. The subsequent fractionation of plagioclase, pyroxene, and amphibole from the residual melt produced the more intermediate suites of monzogabbro/monzodiorite. The evolved magma ascended upward into the shallow crust to form monzonite by K-feldspar fractionation. The residual melt then intruded at shallower depth to form syenite/augite-syenite with abundant microcline crystals. The granodiorite suite was probably generated from lower crustal melts associated with the mafic end members. Later mafic diabase/dykes were likely generated by further partial melting of the same source at depth that were injected into the other suites.