scholarly journals Improved imaging and analysis of chlorite in reservoirs and modern day analogues: new insights for reservoir quality and provenance

2018 ◽  
Vol 484 (1) ◽  
pp. 189-204 ◽  
Author(s):  
R. H. Worden ◽  
James E. P. Utley ◽  
Alan R. Butcher ◽  
J. Griffiths ◽  
L. J. Wooldridge ◽  
...  

AbstractChlorite is a key mineral in the control of reservoir quality in many siliciclastic rocks. In deeply buried reservoirs, chlorite coats on sand grains prevent the growth of quartz cements and lead to anomalously good reservoir quality. By contrast, an excess of chlorite – for example, in clay-rich siltstone and sandstone – leads to blocked pore throats and very low permeability. Determining which compositional type is present, how it occurs spatially, and quantifying the many and varied habits of chlorite that are of commercial importance remains a challenge. With the advent of automated techniques based on scanning electron microscopy (SEM), it is possible to provide instant phase identification and mapping of entire thin sections of rock. The resulting quantitative mineralogy and rock fabric data can be compared with well logs and core analysis data. We present here a completely novel Quantitative Evaluation of Minerals by SCANning electron microscopy (QEMSCAN®) SEM–energy-dispersive spectrometry (EDS) methodology to differentiate, quantify and image 11 different compositional types of chlorite based on Fe : Mg ratios using thin sections of rocks and grain mounts of cuttings or loose sediment. No other analytical technique, or combination of techniques, is capable of easily quantifying and imaging different compositional types of chlorite. Here we present examples of chlorite from seven different geological settings analysed using QEMSCAN® SEM–EDS. By illustrating the reliability of identification under automated analysis, and the ability to capture realistic textures in a fully digital format, we can clearly visualize the various forms of chlorite. This new approach has led to the creation of a digital chlorite library, in which we have co-registered optical and SEM-based images, and validated the mineral identification with complimentary techniques such as X-ray diffraction. This new methodology will be of interest and use to all those concerned with the identification and formation of chlorite in sandstones and the effects that diagenetic chlorite growth may have had on reservoir quality. The same approach may be adopted for other minerals (e.g. carbonates) with major element compositional variability that may influence the porosity and permeability of sandstone reservoirs.

2013 ◽  
Vol 807-809 ◽  
pp. 2170-2173
Author(s):  
Fa Xu ◽  
Peng Hui Zhang ◽  
Jin Liang Zhang ◽  
Ming Zhang

Diagenetic facies are rock bodies that reflect the synthesis of diagenetic characteristics and determine the exploration of favorable reservoirs. A study of the diagnenetic facies of Paleocene sandstones in Lishui Sag (China) was undertaken to unravel the controls on reservoir quality. Samples were studied using petrography, thin sections, scanning electron microscopy, and X-ray diffraction, and thus nine types of diagenetic facies were identified. Reservoir quality is mainly controlled by unstable grains dissolution facies and siderite cementation facies.


Author(s):  
Nakazo Watari ◽  
Yasuaki Hotta ◽  
Yoshio Mabuchi

It is very useful if we can observe the identical cell elements within the same sections by light microscopy (LM), transmission electron microscopy (TEM) and/or scanning electron microscopy (SEM) sequentially, because, the cell fine structure can not be indicated by LM, while the color is; on the other hand, the cell fine structure can be very easily observed by EM, although its color properties may not. However, there is one problem in that LM requires thick sections of over 1 μm, while EM needs very thin sections of under 100 nm. Recently, we have developed a new method to observe the same cell elements within the same plastic sections using both light and transmission (conventional or high-voltage) electron microscopes.In this paper, we have developed two new observation methods for the identical cell elements within the same sections, both plastic-embedded and paraffin-embedded, using light microscopy, transmission electron microscopy and/or scanning electron microscopy (Fig. 1).


2004 ◽  
Vol 36 (1) ◽  
pp. 607 ◽  
Author(s):  
I. Vakalas ◽  
G. Ananiadis ◽  
A. Zelilidis ◽  
N. Kontopoulos ◽  
B. Tsikouras

A number of polished thin sections from two cross sections within the Pindos foreland deposits were petrographically examined while microanalyses on certain minerals were carried out. Chemistry of these minerals is compared to analogous phases occurring in several formations in the neighbourhood of the studied areas which can stand as source areas. Our results reveal that the most probable source materials include the Pindos, Koziakas (and probably and Vourinos) ophiolite complexes, as well as metamorphic sequences of the Pelagonian Zone


2013 ◽  
Vol 19 (2) ◽  
pp. 420-424 ◽  
Author(s):  
Alessandro Croce ◽  
Maya Musa ◽  
Mario Allegrina ◽  
Paolo Trivero ◽  
Caterina Rinaudo

AbstractFerruginous bodies observed in lungs of patients affected by mesothelioma, asbestosis, and pulmonary carcinoma are important to relate the illness to exposure, environmental or occupational, to asbestos. Identification of the inorganic phase constituting the core of the ferruginous bodies, formed around asbestos but also around phases different from asbestos, is essential for legal purposes. Environmental scanning electron microscopy/energy dispersive spectroscopy was used to identify the fibrous mineral phase in the core of ferruginous bodies observed directly in thin sections of tissue, without digestion of the biological matrix. Spectra were taken with sequential analyses along a line crossing the core of the ferruginous bodies. By comparing the spectra taken near to and far from the core, the chemical elements that make up the core could be identified.


2000 ◽  
Vol 6 (S2) ◽  
pp. 872-873
Author(s):  
James R. Rosowski ◽  
Terry L. Bartels ◽  
James F. Colburn ◽  
Jannell L. Colton ◽  
Denton Belk ◽  
...  

Tadpole shrimp inhabit temporary freshwater pools and ponds where their occurrence is largely regulated by rainfall events and water temperature. When dry basins are flooded, cysts of Triops imbibe water and hatch to produce rapidly growing, carapaced larvae. While previous studies show anostracan (fairy shrimp) cyst-surface morphology often species specific, few studies illustrate shell ultrastructure of Triops and none has considered T. longicaudatus. Here we examine the shell of T. longicaudatus (Notostraca) and compare its fine structure to other species of Triops and to that of Artemiafranciscana(Anostraca), which we previously studied.Cysts, produced in culture from Utah broodstock, were purchased from Triops, Inc., 1924 Creighton Rd., Pensacola, FL 32504. Thin sections of cysts were prepared for transmission electron microscopy (TEM) as previously described (Fig. 1). Cysts were also examined with scanning electron microscopy (SEM), dry, whole or fractured (Figs. 2,3), or after imbibition and/or hatching in oxygen saturated, double-distilled water, at 25 ° C.


1986 ◽  
Vol 64 (12) ◽  
pp. 3075-3078 ◽  
Author(s):  
N. Sahashi ◽  
J. Ueno

Morphological studies on pollen grains of Ginkgo biloba L. and Cycas revoluta Thunb. were carried out by scanning electron microscopy. The pollen grains of both species are generally oblong with 1-sulcate apertures which are shrunken as a result of dryness. However, the swollen grains show an almost spherical form with a large and rounded germinal aperture. This aperture may not correspond to any aperture type so far known, although the term "anaporate" can be fitted to the swollen pollen grains. Auricular projections, which may be derived from protrusions of the ectosexine, can be seen sometimes on the surface of the pollen grains. These projections remind us of degraded versions of the bladders that may have been present on the pollen grains of the fossil ancestor. The inner side of the exine, which can be seen in thin sections obtained with the freezing microtome, is ornamented with reticulumlike sculptures. These endosculptures may be the first reported among gymnosperm pollen grains.


2003 ◽  
Vol 88 (4) ◽  
pp. 1903-1906 ◽  
Author(s):  
Alessandro Riva ◽  
Felice Loffredo ◽  
Alessandro Uccheddu ◽  
Francesca Testa Riva ◽  
Bernard Tandler

By taking advantage of a modified osmium maceration technique, we have been able to examine by high resolution scanning electron microscopy (HRSEM) the interior of human adrenocortical mitochondria from which all soluble material has been extracted. The so-called vesicles apparent in thin sections examined by transmission electron microscopy actually are finger-like cristae as determined by HRSEM. These digitiform cristae have a segmented appearance and a bulbous tip. The segmented form of the cristae may have important metabolic implications.


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