• Geomechanics and Engineering
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• v.20 no.6
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• pp.537-546
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• 2020

Oil and natural gas reserves have been recognised abundantly in clayey rich rock formations in deep costal reservoirs. It is necessary to understand the sedimentary history of those reservoir rocks to well explore these natural resources. This work designs a group of laboratory experiments to mimic the physical process of the sedimentary clay-rich rock formation. It presents characterisation results of the physical properties of the artificial clayey rocks synthesized from illite clay, quartz sand and brine water by high-pressure consolidation tests. Special focus is given on the effects of illite clay content and high-stress consolidation on the physical properties. Multi-step loaded consolidation experiments were carried out with stress up to 35 MPa on mixtures constituting of the illite clay, quartz sand and brine water with five initial illite clay contents (w=85%, 70%, 55%, 40% and 25%). Compressibility and void ratio were characterised throughout the physical compaction process of the mixtures constituting of five illite clay contents and their water permeability was measured as well. Results show that the applied stress induces a great reduction of clayey rock void ratio. Illite clay contents has a significant influence on the compressibility, void ratio and the permeability of the physically synthesized clayey rocks. There is a critical illite clay content w=70% that induces the minimum void ratio in the physically synthesised clayey rocks. The SEM study indicates, in the high-pressure synthesised clayey rocks with high illite clay contents, the illite clay minerals are located in layers and serve as the material matrix, and the quartz minerals fill in the inter-mineral pores or are embedded in the illite clay matrix. The arrangements of the minerals in microscale originate the structural anisotropy of the high-pressure synthesised clayey rock. The test findings can give an intuitive physical understanding of the deep-buried clayey rock basins in energy reservoirs.

• Journal of Environmental Impact Assessment
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• v.17 no.6
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• pp.321-333
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• 2008

Considering risks and artificial enrichments of metals in the soils of the study area, the study aims to analyze geology, grain size and geochemistry. Geology is mainly composed of gneisses and phyllites of metamorphic rocks, sandstones, siltstones, shales, tuffs of sedimentary ones and granites and andesites of igneous ones in the area. In the area, mean contents of metals are not meaningful in accordance with petrogenesis. The soil textures of the area are of S, lS and sL of sandy soil, L, scL, cL of loam and C, zC and sC of clayey soil. Mean contents of Ni, Cr, Co and Cu are meaningfully high in loam and clayey soil relative to sandy soil, whereas Ni, Zn, Cd contents are higher in clayey soil than in loam. Those differences imply the metallic contents are dependent to grain size. Based on the metal contents in the soils of the study area, Cu and Zn in loams and Pb in sandy soils are corresponded to soil contamination warning standards, and As showing 75mg/kg of maximum content in loams is assigned to soil contamination countermeasure standards, respectively. Artificial enrichment factor minimized wall rock and grain size relations is over 1 in Cr, Ni and Cu, but the factor is below 1 in average of other metals.