CLAY MINERALS IN THE CORE SAMPLES OF THE MINERALIZED ZONE AT NIIDA, SOUTHERN PART OF ODATE, AKITA PREFECTURE, JAPAN

The results of fossil diatoms investigation from the deltaic sediments are presented. Samples were obtained from the core DM-1 and two Holocene outcrops from the Damchik region of the Astrakhan Nature Reserve. In the core samples eight periods of sedimentation based on diatom analysis were identified: the sediments formed in shallow freshwater basins and deltaic channels. The samples from the outcrops were investigated in much greater detail.

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Enhanced and Rock Typing-Based Reservoir Characterization of the Palaeocene Harash Carbonate Reservoir-Zelten Field-Sirte Basin-Libya

10.2118/205971-ms ◽

2021 ◽

Author(s):

Mohamed Masoud ◽

W. Scott Meddaugh ◽

Masoud Eljaroshi ◽

Khaled Elghanduri

Keyword(s):

Rock Type ◽

Carbonate Reservoir ◽

Classification Model ◽

Reservoir Rocks ◽

The Core ◽

Core Samples ◽

Rock Types ◽

Rock Typing ◽

Open Hole ◽

Type Classification

Abstract The Harash Formation was previously known as the Ruaga A and is considered to be one of the most productive reservoirs in the Zelten field in terms of reservoir quality, areal extent, and hydrocarbon quantity. To date, nearly 70 wells were drilled targeting the Harash reservoir. A few wells initially naturally produced but most had to be stimulated which reflected the field drilling and development plan. The Harash reservoir rock typing identification was essential in understanding the reservoir geology implementation of reservoir development drilling program, the construction of representative reservoir models, hydrocarbons volumetric calculations, and historical pressure-production matching in the flow modelling processes. The objectives of this study are to predict the permeability at un-cored wells and unsampled locations, to classify the reservoir rocks into main rock typing, and to build robust reservoir properties models in which static petrophysical properties and fluid properties are assigned for identified rock type and assessed the existed vertical and lateral heterogeneity within the Palaeocene Harash carbonate reservoir. Initially, an objective-based workflow was developed by generating a training dataset from open hole logs and core samples which were conventionally and specially analyzed of six wells. The developed dataset was used to predict permeability at cored wells through a K-mod model that applies Neural Network Analysis (NNA) and Declustring (DC) algorithms to generate representative permeability and electro-facies. Equal statistical weights were given to log responses without analytical supervision taking into account the significant log response variations. The core data was grouped on petrophysical basis to compute pore throat size aiming at deriving and enlarging the interpretation process from the core to log domain using Indexation and Probabilities of Self-Organized Maps (IPSOM) classification model to develop a reliable representation of rock type classification at the well scale. Permeability and rock typing derived from the open-hole logs and core samples analysis are the main K-mod and IPSOM classification model outputs. The results were propagated to more than 70 un-cored wells. Rock typing techniques were also conducted to classify the Harash reservoir rocks in a consistent manner. Depositional rock typing using a stratigraphic modified Lorenz plot and electro-facies suggest three different rock types that are probably linked to three flow zones. The defined rock types are dominated by specifc reservoir parameters. Electro-facies enables subdivision of the formation into petrophysical groups in which properties were assigned to and were characterized by dynamic behavior and the rock-fluid interaction. Capillary pressure and relative permeability data proved the complexity in rock capillarity. Subsequently, Swc is really rock typing dependent. The use of a consistent representative petrophysical rock type classification led to a significant improvement of geological and flow models.

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Study on the Effect of High-Temperature Heat Treatment on the Microscopic Pore Structure and Mechanical Properties of Tight Sandstone

Geofluids ◽

10.1155/2021/8886186 ◽

2021 ◽

Vol 2021 ◽

pp. 1-13

Author(s):

Liangbin Dou ◽

Guanli Shu ◽

Hui Gao ◽

Jinqing Bao ◽

Rui Wang

Keyword(s):

Mechanical Properties ◽

Heat Treatment ◽

Pore Structure ◽

Water Cooling ◽

Tight Sandstone ◽

The Core ◽

Core Samples ◽

High Temperature Heat Treatment ◽

Different Temperatures ◽

Cooling Methods

The investigation of changes in physical properties, mechanical properties, and microscopic pore structure characteristics of tight sandstone after high-temperature heat treatment provides a theoretical basis for plugging removal and stimulation techniques, such as high energy gas fracturing and explosive fracturing. In this study, core samples, taken from tight sandstone reservoirs of the Yanchang Formation in the Ordos Basin, were first heated to different temperatures (25-800°C) and then cooled separately by two distinct cooling methods—synthetic formation water cooling and natural cooling. The variations of wave velocity, permeability, tensile strength, uniaxial compressive strength, and microscopic pore structure of the core samples were analyzed. Experimental results demonstrate that, with the rise of heat treatment temperature, the wave velocity and tensile strength of tight sandstone decrease nonlinearly, yet its permeability increases nonlinearly. The tight sandstone’s peak strength and elastic modulus exhibit a trend of the first climbing and then declining sharply with increasing temperature. After being treated by heat at different temperatures, the number of small pores varies little, but the number of large pores increases obviously. Compared to natural cooling, the values of physical and mechanical properties of core samples treated by synthetic formation water cooling are apparently smaller, whereas the size and number of pores are greater. It can be explained that water cooling brings about a dramatic reduction of tight sandstone’s surface temperature, generating additional thermal stress and intensifying internal damage to the core. For different cooling methods, the higher the core temperature before cooling, the greater the thermal stress and the degree of damage caused during the cooling process. By taking into consideration of changes in physical properties, mechanical properties, and microscopic pore structure characteristics, the threshold temperature of tight sandstone is estimated in the range of 400-600°C.

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Marmacuma samimei gen. et sp. nov., (Peracarida; Cumacea; Nannastacidae) from Tarantian (Upper Pleistocene) sediments from the Sea of Marmara, Turkey

Zootaxa ◽

10.11646/zootaxa.4718.1.11 ◽

2020 ◽

Vol 4718 (1) ◽

pp. 134-144

Author(s):

M. LEVENT ARTÜZ ◽

MEHMET SAKINÇ

Keyword(s):

New Genus ◽

Lower Edge ◽

Sea Of Marmara ◽

New Genus And Species ◽

Upper Pleistocene ◽

The Core ◽

Core Samples ◽

The Family

A new genus and species of Cumacea, Marmacuma samimei gen. et sp. nov., belonging to the family Nannastacidae is described based on the carapace from the core samples taken from several sites in the Sea of Marmara. The new genus differs from others in the family by the ornamentation of its carapace and strong serration on the lower edge. This is the first cumacean species which is detected from the Tarantian (0.126–0.0117 Ma; Upper Pleistocene) sediments of the Sea of Marmara, Turkey.

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Effects of tectonically induced fabrics on geomechanical properties of rocks, NW Pakistan

Bulletin of Engineering Geology and the Environment ◽

10.1007/s10064-020-01862-3 ◽

2020 ◽

Vol 79 (9) ◽

pp. 4905-4916

Author(s):

Asghar Ali ◽

Saddam Hussain ◽

Shehzad Khan ◽

Awal Sher Khan ◽

Sohail Mabood ◽

...

Keyword(s):

Tensile Strength ◽

Applied Load ◽

Shear Zones ◽

Indian Plate ◽

Uniaxial Tensile ◽

Geomechanical Properties ◽

Uniaxial Tensile Strength ◽

The Core ◽

Core Samples ◽

Crenulation Cleavage

Abstract The Chakdara Granitic Gneisses (CGG) of the Indian plate and Kamila Amphibolite of the Kohistan Island Arc (KIA) along the Main Mantle Thrust (MMT) in Shigo Kas, Talash Dir Lower, indicate that tectonically induced foliations and lineations strongly affected the geomechanical properties of these rocks. The earlier S1 crenulated cleavages are well preserved in the microlithon of a well-developed ENE-WSW trending S2 crenulation cleavage. The pervasive S2 foliations, D2 fold axes, and L22 lineations are induced by NNW-SSE horizontal bulk shortening. The core samples obtained parallel and perpendicular to the main ENE-WSW trending S2 and L22 have higher and lower uniaxial compressive strength (UCS) values, respectively. The UCS and uniaxial tensile strength (UTS) average values of four core samples obtained parallel and perpendicular to the main S2 are 51.8 MPa and 12.21 MPa versus 45.65 MPa and 12.45 MPa, respectively. Core samples from the weakly foliated S-2 specimen shows little variation in the UCS and UTS values. The variation in the UCS values in the core samples cut perpendicular and parallel to the main tectonic fabric has been controlled by micro-shear zones at the contact zones of crenulated and crenulation cleavages and sigmoidal mica fish. The UCS values are higher in the core samples parallel to the pervasive S2 and L22 because the parallel shear on the sigmoidal crenulated cleavages in microlithon of the S2 and S2 mica fish counterbalance the parallel external applied load. However, the UCS values decrease in the core samples that were cut perpendicular to the pervasive S2 and L22 because the perpendicular shear on the sigmoidal crenulated cleavages in microlithon of the S2 and S2 mica fish enhances the external applied load, which lead to the failure of core samples.

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Distribution of As and As(V) adsorption potential onto topsoil in the Datong Basin, northern China

E3S Web of Conferences ◽

10.1051/e3sconf/20199809004 ◽

2019 ◽

Vol 98 ◽

pp. 09004

Author(s):

Zeyong Chi ◽

Xianjun Xie ◽

Yanxin Wang

Keyword(s):

Clay Minerals ◽

Geochemical Modeling ◽

Northern China ◽

Composition Analysis ◽

Strong Positive Correlation ◽

Isothermal Adsorption ◽

Positive Correlation ◽

Core Samples ◽

Datong Basin ◽

Groundwater Irrigation

Datong Basin is a typical groundwater irrigation area in northern China contaminated by As. In order to reveal the distribution of As and the adsorption behavior of As(V) onto topsoil in the Datong Basin, a total of 40 topsoil core samples were collected from a 2 m core. Samples were used for chemical composition analysis and an isothermal adsorption experiment. Results show that the collected samples are not contaminated. The adsorption capacity (Stot value) of topsoil for As(V) at the study site ranged from 257 to 1027 nmol/g with an average of 505.2 ± 200.2 nmol/g. Vertically, both Stot value and topsoil components exhibit a vertical zoning with a positive correlation between the Stot value and K2O, CaO, MgO, Al2O3, Fe2O3 contents while Na2O and SiO2 are inversely correlated. Fe2O3 content shows a strong positive correlation with As content while Al2O3 does not. Moreover, the correlation between Stot value and Al2O3 is much better than Fe2O3. These results indicate that Fe minerals are the main reservoirs of As in the natural topsoil at the study site. Furthermore, both Fe minerals and clay minerals can adsorb As(V), but clay minerals have a greater storage potential. This result indicate that a combined effect of Fe minerals and clay minerals for As(V) accumulation onto topsoil should be considered during geochemical modeling and further agricultural management.

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Mobility of Uranium, Thorium and Lanthanides Around the Bangombe Natural Reactor (Gabon)

MRS Proceedings ◽

10.1557/proc-353-1187 ◽

1994 ◽

Vol 353 ◽

Cited By ~ 5

Author(s):

R. Bros ◽

F. Gauthier-Lafaye ◽

P. Larque ◽

J. Samuel ◽

P. Stille

Keyword(s):

Rare Earth ◽

Rare Earth Elements ◽

Clay Minerals ◽

Nuclear Reactor ◽

Black Shales ◽

Weathering Profile ◽

The Core ◽

Reducing Conditions ◽

Isotopic Studies ◽

Textural Evidence

AbstractNew mineralogical and isotopic studies were carried out on samples from the Bangombé natural nuclear reactor. This reactor is located at shallow depth in the weathering profile and has been subjected to severe supergene alteration. Textural evidence indicates partial dissolution of uraninite in the Bangombé ore related to precipitation of Fe-Ti oxi-hydroxides and clay minerals (kaolinite and metahalloysite). As a consequence of the alteration of the uraninite, uranium and f issiogenic rare earth elements were released in the clayey border of the reactor, whereas radiogenic 232Th remained confined in the close vicinity of the core. A retention effect is also evidenced, under reducing conditions, in the black shales located above the reactor.

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