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Аргиллиты и Глины!
Andrew: Вопрос вот возник недавно. В чём разница между аргиллитами и глинами при выделении их по комплексу методов?
Ответов - 14
bne: Если вне литологического контекста то разница в степени уплотненности Обычно аргиллиты это уплотненные глины только с малым числом разбухающих компонент Это сказывается на снижении электрохимической активности Отсюда разница по нейтронным свойствам и сопротивлению С ПС фактор уплотнения может работать в разные стороны
Andrew: Получается наверно, что аргиллиты = сцементированные глины и в хим.формулу не входит вода. В общем чётко по тому или иному методу ГИС не разделить эти два литотипа.
bne: Повидимому грубо можно сказать, что глина мнется, а аргиллит ломается Но на кривой уплотнения (области условно разделяются) И само собой и акустика и нейтронный и в меньшей мере плотностной и сопротивление реагируют
Bne_Home7: Случайно набрел http://www.shalebase.com/index.htm Правда ни объем ни цена не ясны Но некие физсвойства определены
Василий: Чегото ваобще никакой канкретики. Голая вода какаето. Как таковой там базы нет.
bne: Там есть намек на такую работу А про цены и прочее - видимо предмет договора Не удивлюсь, если и россиянин к бизнес-схеме причастен Когда-то в сети был проект базы по бассейнам, но давно его не видел Может снова вынырнет (как и Василий) ;-))
Василий: ))Прощу прощения, что давно не появлялся, женился блин, не до того было) боялся быть засасоным данным форумом. )
bne: Рад видеть Сам постоянно между Москвой и Мумбаем и то с насморком то с радикулитом Счастья Вам в личной жизни ;-)
Andrew: Поздравляю, Василий! Долгих вам так сказать и счастливых моментов! ;-)
Василий: Большое спасибо! Приятно )
bne: Просмотрел кучу литературы которую сумел перебрать (в основном западные источники) Судя по ним у рифов и барьерных рифов встречаются области в которые выносит мелкие фракции от нерастворимого остатка до пеллет и битых раковин моллюсков (обычно это по краям) Области эти могут быть погружены на глубины до 30-70 метров и в них оседает эта муть Содержание глинистой компоненты там может достигать 30-40% В принципе в Mudstone обычно заносят породы в которых относительно крупных компонент менее 10-20% Неприятности с ГК (аномалии) могут быть обусловлены высоким содержанием фосфоритов, аномалиями EH (уран), остатками органики (рыб) И (само-собой) играет роль битуиы и сорбция урана Мнение Fertl о возможной сорбции урана в трещинах в ходе фильтрации Р.А. Резванов считает неубедительным (попытался и с ним проконсультироваться по этой теме)
bne: Mudstone microstructure evolution during diagenesis: effect on cap rock sealing capacity Charpentier, D.; Worden, R. H.; Fisher, Q. J.; Aplin, A. C. EGS - AGU - EUG Joint Assembly, Abstracts from the meeting held in Nice, France, 6 - 11 April 2003, abstract #14167 Mudstone properties control some important characteristics of sedimentary basins, such as how fluids move from or are contained within aquifers and petroleum bearing-rocks. Despite the volumetric dominance of mudstones in sedimentary basins, there are many basic issues that are as yet unresolved such as what controls permeability and how mud become mudstone. To investigate the relationship between porosity, permeability, fabrics and mineralogy transformations, and to determine the parameters influencing the controls on mudstones properties, a large range of microstructural and petrophysical techniques have been used on core and cuttings mudstone samples from the Gulf of Mexico and North Sea. At the time of deposition, mudstones usually have randomly aligned detrital clay minerals and have high porosity and permeability (respectively 60--90% and 10-11-10-14 m^2). Mudstones contain a variety of minerals: mainly clay minerals, silt-grade framework silicates, carbonate detritus and sulphides. By a combination of mechanical and chemical processes mudstone mineralogy and properties change during burial and diagenesis. Porosity rapidly diminishes although it can still be significant (15--25%) even after several thousand meters of burial. The degree of alignment of clay minerals tends to increase. Mudstone mineral assemblages change with common detrital smectite replaced by illite. Grain alignment at the microscale (˜400--1,000 μm^2) and the collapse of porosity occur during the replacement of smectite by illite, thousands of meters of overburden alone do not induce the development of aligned clay fabric in mudstones. Microfabric and porosity content thus seem to be a consequence of the kinetically (thermally) controlled illitization of smectite that is therefore a chemical compaction process. Mesoscale fabric (˜10,000 μm^2) including bedding, is controlled by the abundance of silt (diminishing the order) and the contrasting effect of the abundance of relatively large detrital mica grains (locally enhancing the order). Permeability variations seem to be function of lithology and can be correlated with the mesoscale fabric. Our studies suggest that the two major controls on permeability and sealing capacity might be the initial bulk mudstone mineralogy and the thermal history. http://adsabs.harvard.edu/abs/2003EAEJA....14167C
bne_mumbai2: From Mud to Shale - Mechanical and Chemical Compaction of Mudstones Jens Jahren, Knut Bjшrlykke, Шyvind Marcussen, Chris Peltonen, and Nazmul Haque Mondol Department of Geosciences, University of Oslo, P.O. Box 1047 Blindern, 0316 Oslo, Norway The transition from soft clays and mudstone to hard shales is still relatively poorly understood. This change can be observed by testing core samples geomechanically and by examining the change in well log velocity and density. The part of this compaction process which is mechanical can be tested in the laboratory but the chemical compaction is more difficult to reproduce. In sandstones the degree of cementation by quartz and other cementing minerals can readily be examined. In mudstones carbonate cement is easy to detect, but quartz cement is in most cases difficult to observe. Yet we know that significant amounts of silica have been released by diagenetic reactions must have precipitated as quartz. In the absence of carbonate cements it is difficult to explain the increase in stiffness, density and velocity without a cementing mineral. The compaction can not be explained by mechanical processes alone. Sediment composition and diagenesis vary substantially in siliciclastic sedimentary basins but most fine grained sediments contain unstable minerals and amorphous material that will produce quartz cement above 60-80oC. Quartz precipitation will not take place in most mudstones at lower temperatures for kinetic reasons. Amorphous silica (Opal A) from siliceous organisms is the most obvious silica source. The distribution and amount of amorphous silica from this source will be a function of sedimentary facies. The clay mineral smectite will also if present contribute substantially to silica cementation. Smectite is particularly important in basins with substantial volcanic input. Silica will be released when smectite is illitized (smectite + K+ = Illite + Silica + H2O). Amorphous silica will recrystallize in steps forming several metastable silica phases before the stable end product micro-crystalline quartz is formed. Micro-crystalline quartz is formed due to low quartz growth rate at low temperatures, thus favouring nucleation of many new micro-crystalline quartz grains rather than overgrowths on detrital sand and silt particles. Neoformed micro-crystalline quartz is readily identified in mudstones by electron optical methods like high resolution scanning electron microscopy. Recrystallization of amorphous silica is probably finished before substantial amounts of smectite are illitized because the illitization reaction requires a silica saturation approaching quartz solubility. Illitization of smectite is for geometrical reasons in tight mudstones unlike in sandstones a relatively slow process. This is probably related to slow diffusion of potassium from dissolving potassium containing minerals like K-feldspars present in the sediment. Mixed layer illite/smectite (I/S) will therefore survive for a while in mudstones before all smectite is transformed to illite. This rather complicated low temperature (60-80oC) silica diagenesis is clearly seen as a marked velocity increase in well log data indicating sediment stiffening caused by silica cementation. The formation of small stiff illite crystals is also expected to contribute somewhat to the overall stiffening of the sediment. The overall velocity vs. density gradient is also changed by this reaction indicating that mechanical compaction is unimportant compared to chemical compaction below this transition temperature in mudstones. Mechanical smectite compaction tests show no sign of a stress related velocity change as a function of density supporting the above conclusion. Other diagenetic reactions in mudstones like illitization of kaolinite (Kaolinite + K+ = Illite + Silica + H2O) commencing at higher temperatures (>120-130oC) continue the chemical compaction processes found in mudstones involving the release of silica and precipitation of quartz. AAPG Search and Discover Article #90066©2007 AAPG Hedberg Conference, The Hague, The Netherlands http://www.searchanddiscovery.net/abstracts/html/2007/hedberg/short/jahren.htm
bne_mumbai2: Презентация From Mud to Shale: the Role of Microquartz Cementation http://www.searchanddiscovery.net/documents/2009/50206jahren/ndx_jahren.pdf
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