Stimulation of Multilayered High-Carbonate-Content Sandstone Formations in West Africa Using Chelant-Based Fluids and Mechanical Diversion

2010 ◽  
Author(s):  
Mark Parkinson ◽  
Trevor Kenneth Munk ◽  
Jess G. Brookley ◽  
Agostinho Domingos Caetano ◽  
Marcos Antonio Albuquerque ◽  
...  
Keyword(s):  
West Africa ◽  
Carbonate Content ◽  
High Carbonate ◽  
High Carbonate Content ◽  
Stimulation Of

Formation of high-transmisivity zones in the facies transition in the Bohemian Cretaceous Basin (Czech Republic) 

2021 ◽  
Author(s):  
Jiri Stary ◽  
Jana Schweigstillova ◽  
Jiri Bruthans
Keyword(s):  
Czech Republic ◽  
Hydrochloric Acid ◽  
Marine Sponges ◽  
Carbonate Content ◽  
Rock Outcrops ◽  
The Czech Republic ◽  
High Carbonate ◽  
Bohemian Cretaceous Basin ◽  
High Carbonate Content ◽  
Facies Transition

<p>The Bohemian Cretaceous Basin (BCB) is the most important hydrogeological structure in the Czech Republic, with large sources of groundwater. The origin of high-transmissivity zones is poorly understood in many BCB areas. The doyen of Czech hydrogeology prof. Hynie described some of the largest springs to be of karst origin and he attributed the most permeable areas to facies transition between shallow-water sandstones and deep-water marlstones. In many BCB areas with large springs we can find thin sandstones and siltstones layers with high carbonate content even in stratigraphical levels corresponding with aquifers.</p><p>Research is focused on Vysoké Mýto and Ustí synclines in BCB, 125 km east of Prague in the Czech Republic. Overall 167 rock samples were taken from borehole cores and rock outcrops in this area, the most from Jizera and Bílá Hora formations. Cores were taken from intervals where: (i) high carbonate content was expected, (ii) conduits and enlarged fractures were observed at outcrops and in wells, (iii) inflows to boreholes were determined by well logging. Calcium carbonate content was determined by calcimetry in cores. Cores were leached in 10 % hydrochloric acid to observe the degree of subsequent disintegration. Polished sections were prepared from selected cores and Ca, Si, Na, K, Al content was automatically mapped by SEM-EDS to visualize the calcium, silica, feldspar and clay mineral distribution in cores.</p><p>Leaching in hydrochloric acid is an accelerated simulation of natural processes of dissolution by acidic solutions (Kůrková et al. 2019). In many aquifers in BCB there are thin calcite-rich layers with quartz sand which disintegrates after leaching calcite. Leaching of the samples in acid results in the decrease of sample strength, sometimes to their disintegration. Leaching experiments showed that the carbonate content is not the only controlling factor in the karstification process.</p><p>In sediments with detrital quartz admixture in central or western parts of the BCB the total disintegration mostly occurs between 35-50% CaCO<sub>3</sub> content depending on insoluble material content (Kůrková et al. 2020). In contrast, in the eastern part of the BCB, a degree of disintegration above 10% is documented in only 7% of the studied samples. In sediments with diagenetically precipitated cement from marine sponges even calcite content as high as 80% may not be sufficient for material to disintegrate after leaching. Disintegration occurs mainly along fractured zones where rock is heavily fractured.  </p><p>It seems that the increased content of microcrystalline silica cementy in sandy limestones and calcareous sandstones (spongolites) of the studied area has a fundamental influence on the higher cohesion and resistance of rocks to dissolution. Cause for increased cohesion is the specific spatial distribution of  microcrystalline silica, which bound the quartz grains together or formed a foam-like supporting structure in fine calcite-rich deposits.</p><p> </p><p>The research was financially supported by the GA ČR 19-14082S.</p><p> </p><p>References:</p><p>Kůrková I., Bruthans J., Balák F., Slavík M., Schweigstillová J., Bruthansová J., Mikuš P., Grundloch J. (2019): Factors controlling evolution of karst conduits in sandy limestone and calcareous sandstone (Turnov area, Czech Republic). Journal of Hydrology: 574: 1062-1073.</p>

scholarly journals New Calcium Carbonate-Based Cements for Bone Reconstruction

2005 ◽  
Vol 284-286 ◽  
pp. 105-108 ◽  
Author(s):  
Marie-Laure Fontaine ◽  
Christèle Combes ◽  
Thierry Sillam ◽  
Gérard Dechambre ◽  
Cristian Rey
Keyword(s):  
Calcium Carbonate ◽  
Aqueous Media ◽  
Carbonate Content ◽  
Carbonated Apatite ◽  
Phosphate Phase ◽  
High Carbonate ◽  
Final Composition ◽  
Calcium Phosphate Phase ◽  
Good Homogeneity ◽  
High Carbonate Content

The feasibility of calcium carbonate-based cements involving the re-crystallization of metastable calcium carbonate varieties has been demonstrated. Two cement compositions were obtained by mixing either calcium carbonate phases (cement A) or a calcium carbonate and a calcium phosphate phase (cement B) with an aqueous media. These cements set and hardened after 30 minutes and 90 minutes respectively. The final composition of cement A was calcite and aragonite whereas cement B lead to a carbonated apatite analogous to bone mineral. Despite poor mechanical properties the presence of a high carbonate content in the final phase might be of interest to increase the cement resorption rate and to favour its replacement by bone tissue. First assays of implantation performed on fresh anatomical pieces (fresh cadavers) at 37°C revealed important advantages of such cement compositions: easiness of use, rapid setting, good adhesion to bone, very good homogeneity and stability of the cement.

Early carbonate diagenesis within Phanerozoic shales and sandstones of the NW European Shelf

Clay Minerals ◽  
1984 ◽  
Vol 19 (3) ◽  
pp. 309-321 ◽  
Author(s):  
J. G. Gluyas
Keyword(s):  
Organic Matter ◽  
Carbonate Content ◽  
Carbonate Diagenesis ◽  
Bacterial Oxidation ◽  
North West ◽  
Nodular Limestone ◽  
High Carbonate ◽  
Early Carbonate ◽  
Reservoir Potential ◽  
High Carbonate Content

AbstractContinuous nodular limestone beds in north-west European shale sequences developed during early diagenesis via anaerobic, bacterial catabolysis of organic matter which yielded both carbonate and sulphide. The high carbonate content of the nodular limestones (50–90%) demonstrates that they developed in the upper tens of metres of the sediment column. In addition, each of the nodular limestones displays a centrifugal decrease in carbonate, indicating that growth was synchronous with compaction of the host ooze. The chemistry of the carbonate changed with time, becoming more rich in magnesium and iron and reflecting a progressive change in the porewater chemistry from its initially marine composition. The earliest precipitate was calcite containing < 1 mole% MgO; later precipitates contained several percent MgO and ultimately dolomite was precipitated. Similarly, iron content of the carbonate increased as precipitation continued and sulphate reduction, and thus pyrite production, declined. The early diagenetic cementation of many marine sandstones followed a pattern similar to that of nodular limestones and much of the carbonate was also derived from organic matter via bacterial oxidation. Thus, early diagenetic bacterial oxidation of organic matter may not only reduce the source potential of shales but also reduce the reservoir potential of associated sandstones, or those more distant which lie along compactional-fluid pathways.

scholarly journals Distribution of surficial sediments in the Southern Evoikos and Petalioi Gulfs, Greece

2000 ◽  
Vol 1 (1) ◽  
pp. 111 ◽  
Author(s):  
A.P. KARAGEORGIS ◽  
CH. ANAGNOSTOU ◽  
A. SIOULAS ◽  
G. ELEFTHERIADIS ◽  
A. TSIRAMBIDES
Keyword(s):  
Drainage Basin ◽  
Mineralogical Composition ◽  
Carbonate Content ◽  
Surficial Sediments ◽  
Composition Distribution ◽  
Sediment Samples ◽  
Sea Level Fluctuations ◽  
High Carbonate ◽  
Very High ◽  
High Carbonate Content

A series of 123 surficial sediment samples from the Southern Evoikos and Petalioi Gulfs was studied for grain-size properties, carbonate content and mineralogical composition. Distribution of the sediments revealed two sedimentary provinces. The first concerns the Southern Evoikos Gulf, characterised by silty sediments with relatively low carbonate content. Quartz, feldspars, micas, clay and carbonate minerals are the major mineralogical components of the sediments. These sediments are the result of the Asopos River supply during Holocene and they contribute to the formation of smooth bottom morphology. The second province concerns the Petalioi Gulf (Northern and Southern), where the surficial sediments are mainly sandy and characterised by very high carbonate content. Their mineralogical composition reflects the lithology of the drainage basin. Since the modern terrigenous solid supply is limited, these sediments are not considered as products of recent sedimentation, but older deposits (relict sands). Their presence at such depths is justified by sea-level fluctuations and their preservation is due to the low sedimentation rate in the Petalioi Gulf, in combination with the strong hydrodynamic status of the area.

scholarly journals Trifolium Repense L. Breeding In The Central Chernozem Region: Main Directions And Methods Of Work

2021 ◽  
Vol 901 (1) ◽  
pp. 012008
Author(s):  
V M Kosolapov ◽  
V I Cherniavskih ◽  
E V Dumacheva ◽  
N A Sopina ◽  
V I Tseiko ◽  
...  
Keyword(s):  
Carbonate Content ◽  
Seed Productivity ◽  
Construction Waste ◽  
Central Chernozem Region ◽  
High Carbonate ◽  
Initial Forms ◽  
Central Chernozem ◽  
High Carbonate Content ◽  
Variety Testing ◽  
Chalk Outcrops

Abstract Varieties and breeding samples of creeping clover Trifolium repense L. of lawn direction were studied in the nursery of competitive varietal trials. Using the methods of recurrent breeding involving local populations of creeping clover growing on chalk outcrops as initial forms, two varieties ‘Krasnoyaruzhsky’ and ‘Ilyok’ were obtained, as well as a new breeding sample PO 17/07. Varieties ‘Krasnoyaruzhsky’, ‘Ilyok’ and selection sample PO 17/7 are characterized by high seed productivity, the possibility of cultivation on soils with high carbonate content (burial of construction waste in an urban environment, reclamation of man-made-disturbed landscapes, etc.); high resistance to trampling. Seed yield over three years of tests in varieties ‘Krasnoyaruzhsky’, ‘Ilyok’ and breeding sample PO 17/7 significantly exceed the standard by an average of 24,6-26,8%; have uniform foliage at the level of 48-53%. Breeding sample PO 17/7 is planned to be submitted to the State variety testing.

Sedimentary provinces, and associated bedforms and benthos on the Scott Reef-Rowley Shoals platform off north-west Australia

1988 ◽  
Vol 39 (2) ◽  
pp. 133 ◽  
Author(s):  
RJ McLoughlin ◽  
TLO Davis ◽  
TJ Ward
Keyword(s):  
Grain Size ◽  
Carbonate Content ◽  
Sediment Type ◽  
Sediment Grain Size ◽  
North West ◽  
Significant Relationships ◽  
Sediment Types ◽  
Sea Bed ◽  
Mean Grain Size ◽  
High Carbonate

The distribution of sediment types on the Scott Reef-Rowley Shoals platform, a marginal plateau adjoining the continental shelf of north-west Australia, has been investigated. Sediments in this region are predominately muds, with a high carbonate content. Sands, which are scarce, are mainly composed of both benthic and pelagic skeletal remains, with any gravel-sized material consisting of relict molluscan debris and, occasionally, relict coralline material. Correlation of sediment type with sea-bed characteristics as determined from photographs of the bottom at the same site showed significant relationships between mean grain size, and degree of sediment rippling and benthic activity. Similar correlations were found for the skewness measure of the analysis of sediment grain-size frequency. It is concluded that sediment type bears strong relationships with benthic activity and bedform morphology. Correlations between sediment provinces and the distribution of Australian scampi (Metanephrops sp.), a relatively new fishery in the region, are discussed.

Worm tubes in an allochthonous cold-seep carbonate from lower Oligocene rocks of western Washington

2000 ◽  
Vol 74 (6) ◽  
pp. 992-999 ◽  
Author(s):  
James L. Goedert ◽  
Jörn Peckmann ◽  
Joachim Reitner
Keyword(s):  
Cold Seep ◽  
Carbonate Content ◽  
Microbial Oxidation ◽  
Carbonate Cements ◽  
Lower Oligocene ◽  
Tube Worms ◽  
Oxidation Of Hydrocarbons ◽  
High Carbonate ◽  
Depositional Setting ◽  
Seep Carbonate

Tubes suspected to be those of vestimentiferan worms are abundant in carbonate boulders at one locality in the lower Oligocene part of the Lincoln Creek Formation along the Canyon River, Grays Harbor County, Washington. The largest tubes exhibit the same general orientation and are arranged in clusters. The tube walls are preserved as aragonite that is, in some cases, replaced by silica. The original tube walls either had a high carbonate content or were indurated very early by aragonite mineralization of the organic wall. The carbonate cements around, on, and inside of the tubes were precipitated due to the microbial oxidation of hydrocarbons at a cold-seep. After lithification, the carbonate fragmented as it slid or slumped, along with other sedimentary debris, downslope into deeper waters. This is one of the few reports of an ancient cold-seep chemosynthetic community dominated by tube worms, and the third report of an allochthonous cold-seep carbonate within a deep-water depositional setting.

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