Fossil diatoms from the Volga Delta Holocene sediments (Damchik region) as indicators of the paleoecological conditions of sedimentation

2019 ◽  
pp. 270-273
Author(s):  
Yelena I. Shtyrkova ◽  
Yelena I. Polyakova
Keyword(s):  
Nature Reserve ◽  
Diatom Analysis ◽  
Volga Delta ◽  
The Core ◽  
Core Samples ◽  
Holocene Sediments ◽  
Fossil Diatoms

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.

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

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.

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

Geofluids ◽  
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.

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

Zootaxa ◽  
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. 

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

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.

Petrophysical Changes of Sandstone Due to Salt Precipitation and Fines Migration During Carbon Dioxide Injection

2020 ◽  
Vol 17 (2) ◽  
pp. 1207-1213 ◽  
Author(s):  
Muhammad Aslam Md Yusof ◽  
Mohamed Zamrud Zainal ◽  
Ahmad Kamal Idris ◽  
Mohamad Arif Ibrahim ◽  
Shahrul Rizzal M. Yusof ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Damage Mechanism ◽  
Salt Precipitation ◽  
Carbon Dioxide Injection ◽  
Fines Migration ◽  
Flow Rates ◽  
The Core ◽  
Core Samples ◽  
Sandstone Rock ◽  
Porosity And Permeability

Sequestration of Carbon Dioxide (CO2) in sandstone formation filled by brine aquifers is widely considered a promising option to reduce the CO2 concentration in the atmosphere. However, the injection of reactive CO2 into sandstone rock creates injectivity problems because of CO2-brine-rock interactions. The injection flow rate and CO2-fluid-rock exposure conditions are important factors that control the intensity of the reactions. The focus of this research was therefore on evaluating the petrophysical modifications in sandstone core samples at distinct flow rates using different CO2 injection schemes. In this research, the porosity and permeability of Berea sandstone samples were measured using PoroPerm equipment. The core samples were initially saturated with dead brine (30 g/l NaCl) followed by injection either by supercritical CO2 (scCO2) only, CO2-saturated brine only and CO2-saturated brine together with scCO2 at different flow rates. During injection, the differential pressure between the core inlet face and outlet face were recorded. Fines from the produced effluent were separated and collected for characterization using Field Emission Scanning Electron Microscope and Energy Dispersive X-ray Spectroscopy (FESEM-EDX). Post-injection porosity and permeability of the core samples were measured and compared with the pre-injection data to monitor changes. All sandstone core specimens showed favorable storage capability features in the form of capillary residual trapping with residual CO2 saturation ranging from 40% to 48%. In addition, all samples experienced important changes in their petrophysical characteristics, which were more pronounced in the event of absolute porosity and permeability, which decreased from 20%–51% to 4%–32%. The suggested harm mechanism is primarily owing to salt precipitation and fines migration. Supported by FESEM images, the proposed damage mechanism is mainly due to salt precipitation and fines migration.

Identification of preferential flow effects on hydraulic conductivity measurements using a fluorescent tracer

2000 ◽  
Vol 37 (2) ◽  
pp. 479-484
Author(s):  
Tom A Al ◽  
David W Blowes
Keyword(s):  
Hydraulic Conductivity ◽  
Measurement Errors ◽  
Preferential Flow ◽  
Conductivity Measurements ◽  
Fine Grained ◽  
The Core ◽  
Core Samples ◽  
Dye Tracer ◽  
Order Of Magnitude ◽  
Constant Head

Core samples were collected from fractured and unfractured zones within fine-grained, unconsolidated mine tailings. The hydraulic conductivity of the core samples was measured in a constant-head permeameter. A fluorescent dye tracer was added to the constant-head reservoir in the permeameter. The tests were run for approximately 48 h, then the cores were sectioned to observe the distribution of dye. Flow through the fractures results in hydraulic conductivity measurements up to one order of magnitude greater than that of unfractured tailings. Observations of the dye distribution in samples following permeameter measurements are used to identify cases where preferential flow in fractures has influenced the hydraulic conductivity measurements. The dye tracer distribution also indicates where measurement errors may be suspected due to flow leakage around the core sample.Key words: tracers, hydraulic conductivity, fractures, tailings.

Parameter Revision of the Bailey Method on Gradation Examination

2011 ◽  
Vol 255-260 ◽  
pp. 4176-4180
Author(s):  
Yong Li Xu ◽  
Hao Jiang
Keyword(s):  
Theoretical Basis ◽  
Asphalt Pavement ◽  
Asphalt Mixture ◽  
Core Sample ◽  
Parameter Range ◽  
The Core ◽  
Core Samples

The Bailey method put forward three very significant parameters CA, FAc and FAf, provided an effective way for the asphalt mixture gradation test, and it could evaluate the gradation of asphalt pavement core sample effectively. Based on the analysis of common gradation, the parameters of formula was revised, the application conditions of AC mixture and the parameter range for AC mixture was proposed, that based on the gradation which is standard recommended and the core samples in different pavement conditions. The results proposed theoretical basis for gradation examination correctly with the Bailey method.

scholarly journals Stylolite in Upper Cretaceous Carbonate Reservoirs from Northwestern Iraq

2021 ◽  
Author(s):  
Ali Al-Juboury ◽  
Mohammed A. Al-Haj ◽  
Aboosh H. Al-Hadidy
Keyword(s):  
Upper Cretaceous ◽  
Compaction Pressure ◽  
Carbonate Reservoirs ◽  
Thickness Reduction ◽  
Pressure Solution ◽  
Upward Movement ◽  
Thin Sections ◽  
The Core ◽  
Core Samples ◽  
Mineralization Processes

Stylolites are commonly observed in the carbonate reservoirs in various oilfield of Iraq including those of upper Cretaceous successions from northwestern Iraq, where they are characterized by stylolite-rich zones in the Cenomanian-early Turonian Gir Bir Formation and to a lesser extent in the Turonian-Santonian Wajna and early Campanian Mushorah formations respectively. The observed stylolites are either large to be identified in the core samples or smaller ones that are well observed in the thin sections and are characterized by variations in amplitude, morphology and accumulated insoluble residues. The recorded stylolites are classified as hummocky, irregular, low and high-amplitudes peaks, and irregular anastomosing stylolites. Stylolites affect the porosity permeability and thickness reduction compaction as the main chemical compaction (pressure solution) that reduce porosity. Whereas, in other places, the stylolites act as seals and stop the upward movement of hydrocarbons. This is also seen for mineralization processes such as silicification that ended near the stylolite surfaces.

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