Seabed fluid flow: the impact on geology, biology, and the marine environment

The impact of the urban effluents of Mytilene (Lesvos island, Greece) on the receiving coastal marine environment, was evaluated by studying the quality of the city effluents (BOD5, COD, SS, heavy metals) and the marine sediments (grain size, organic matter, heavy metals). It was found that the urban effluents of Mytilene contain high organic matter and suspended particle load because of septage discharge into the sewerage network. Furthermore, although the city does not host important industrial activity, its effluents contain appreciable metal load, which is mainly associated with the particulate phase. The city effluents are discharged into the coastal marine environment and their colloidal and particulate matter after flocculation settles to the bottom, where is incorporated into the sediments. Over the years, the accumulation of organic matter and metals into the harbour mud has created a non-point pollution source in the relatively non-polluted coastal marine environment of the island. Copper and Zn were the metals which presented the higher enrichment in the sediments of the inner harbour of Mytilene.

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Modeling and Experiments of Laser Cladding With Droplet Injection

Journal of Heat Transfer ◽

10.1115/1.2005273 ◽

2005 ◽

Vol 127 (9) ◽

pp. 978-986 ◽

Cited By ~ 48

Author(s):

J. Choi ◽

L. Han ◽

Y. Hua

Keyword(s):

Fluid Flow ◽

Laser Cladding ◽

Dynamic Motion ◽

Cladding Layer ◽

Melt Pool ◽

Material Deposition ◽

Modeling And Experiments ◽

Solid Liquid Interface ◽

Solid Liquid ◽

The Impact

Laser aided Directed Material Deposition (DMD) is an additive manufacturing process based on laser cladding. A full understanding of laser cladding is essential in order to achieve a steady state and robust DMD process. A two dimensional mathematical model of laser cladding with droplet injection was developed to understand the influence of fluid flow on the mixing, dilution depth, and deposition dimension, while incorporating melting, solidification, and evaporation phenomena. The fluid flow in the melt pool that is driven by thermal capillary convection and an energy balance at the liquid–vapor and the solid–liquid interface was investigated and the impact of the droplets on the melt pool shape and ripple was also studied. Dynamic motion, development of melt pool and the formation of cladding layer were simulated. The simulated results for average surface roughness were compared with the experimental data and showed a comparable trend.

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The impact of natural fractures on heat extraction from tight Triassic sandstones in the West Netherlands Basin: a case study combining well, seismic and numerical data

Netherlands Journal of Geosciences – Geologie en Mijnbouw ◽

10.1017/njg.2020.21 ◽

2021 ◽

Vol 100 ◽

Author(s):

Quinten D. Boersma ◽

Pierre Olivier Bruna ◽

Stephan de Hoop ◽

Francesco Vinci ◽

Ali Moradi Tehrani ◽

...

Keyword(s):

Fluid Flow ◽

Heat Production ◽

Positive Impact ◽

Heat Extraction ◽

Natural Fractures ◽

Negative Power ◽

Petrophysical Analysis ◽

Production Values ◽

Geostatistical Inversion ◽

The Impact

Abstract The positive impact that natural fractures can have on geothermal heat production from low-permeability reservoirs has become increasingly recognised and proven by subsurface case studies. In this study, we assess the potential impact of natural fractures on heat extraction from the tight Lower Buntsandstein Subgroup targeted by the recently drilled NLW-GT-01 well (West Netherlands Basin (WNB)). We integrate: (1) reservoir property characterisation using petrophysical analysis and geostatistical inversion, (2) image-log and core interpretation, (3) large-scale seismic fault extraction and characterisation, (4) Discrete Fracture Network (DFN) modelling and permeability upscaling, and (5) fluid-flow and temperature modelling. First, the results of the petrophysical analysis and geostatistical inversion indicate that the Volpriehausen has almost no intrinsic porosity or permeability in the rock volume surrounding the NLW-GT-01 well. The Detfurth and Hardegsen sandstones show better reservoir properties. Second, the image-log interpretation shows predominately NW–SE-orientated fractures, which are hydraulically conductive and show log-normal and negative-power-law behaviour for their length and aperture, respectively. Third, the faults extracted from the seismic data have four different orientations: NW–SE, N–S, NE–SW and E–W, with faults in proximity to the NLW-GT-01 having a similar strike to the observed fractures. Fourth, inspection of the reservoir-scale 2D DFNs, upscaled permeability models and fluid-flow/temperature simulations indicates that these potentially open natural fractures significantly enhance the effective permeability and heat production of the normally tight reservoir volume. However, our modelling results also show that when the natural fractures are closed, production values are negligible. Furthermore, because active well tests were not performed prior to the abandonment of the Triassic formations targeted by the NLW-GT-01, no conclusive data exist on whether the observed natural fractures are connected and hydraulically conductive under subsurface conditions. Therefore, based on the presented findings and remaining uncertainties, we propose that measures which can test the potential of fracture-enhanced permeability under subsurface conditions should become standard procedure in projects targeting deep and potentially fractured geothermal reservoirs.

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Experimental Study of Natural Ions and Rock Interactions for Seawater Breakthrough Percentage Monitoring during Offshore Seawater Flooding

SPE Journal ◽

10.2118/201553-pa ◽

2021 ◽

pp. 1-21

Author(s):

Yanqing Wang ◽

Xiang Li ◽

Jun Lu

Keyword(s):

Porous Media ◽

Fluid Flow ◽

Barium Sulfate ◽

Large Deviation ◽

Exchange Process ◽

Reaction Model ◽

Sodium Content ◽

Flow In Porous Media ◽

Formation Water ◽

The Impact

Summary Seawater breakthrough percentage monitoring is critical for offshore oil reservoirs because seawater fraction is an important parameter for estimating the severity of many flow assurance issues caused by seawater injection and further developing effective strategies to mitigate the impact of those issues on production. The validation of using natural ions as a tracer to calculate the seawater fraction was investigated systematically by studying the natural chemical composition evolution in porous media using coreflood tests and static bottle tests. The applicable range of ions was discussed based on the interaction between ion and rock. The barium sulfate reactive model was improved by integrating interaction between ions and rock as well as fluid flow effect. The results indicate that chloride and sodium interact with rock, but the influence of the interaction can be minimized to a negligible level because of the high concentrations of chloride and sodium. Thus, chloride and sodium can be used as conservative tracers during the seawater flooding process. However, adsorption/desorption may have a large influence on chloride and sodium concentrations under the scenario that both injection water and formation water have low chloride and sodium content. Bromide shows negligible interaction with rock even at low concentrations and can be regarded as being conservative. The application of a barium and sulfate reaction model in coreflood tests does not work as well as in bottle tests because fluid flow in porous media and ion interaction with rock is not taken into account. Although sulfate and barium adsorption on clay is small, it should not be neglected. The barium sulfate reaction model was improved based on the simulation of ion transport in porous media. Cations (magnesium, calcium, and potassium) are involved in the complicated cation-exchange process, which causes large deviation. Therefore, magnesium, calcium, and potassium are not recommended to calculate seawater fraction. Boron, which exists as anions in formation water and is used as a conservative tracer, has significant interactions with core matrix, and using boron in an ion tracking method directly can significantly underestimate the seawater fraction. The results give guidelines on selecting suitable ions as tracers to determine seawater breakthrough percentages under different production scenarios.

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Comparison of Cooling Film Development Calculations for Transpiration Cooled Flat Plates With Different Turbulence Models

Volume 3: Heat Transfer; Electric Power; Industrial and Cogeneration ◽

10.1115/2001-gt-0132 ◽

2001 ◽

Cited By ~ 5

Author(s):

Dieter E. Bohn ◽

Norbert Moritz

Keyword(s):

Fluid Flow ◽

Thermal Barrier Coating ◽

Solid Body ◽

Turbulence Models ◽

Thermal Barrier ◽

Flat Plates ◽

Jet Mixing ◽

Barrier Coating ◽

Film Development ◽

The Impact

A transpiration cooled flat plate configuration is investigated numerically by application of a 3-D conjugate fluid flow and heat transfer solver, CHT-Flow. The geometrical setup and the fluid flow conditions are derived from modern gas turbine combustion chambers. The plate is composed of three layers, a substrate layer (CMSX-4) with a thickness of 2 mm, a bondcoat (MCrAlY) with thickness 0,15 mm, and a thermal barrier coating (EB-PVD, Yttrium stabilized ZrO2) with thickness 0,25 mm, respectively. The numerical grid contains the coolant supply (plenum), the solid body, and the main flow area upon the plate. The transpiration cooling is realized by finest drilled holes with a diameter of 0,2 mm that are shaped in the region of the thermal barrier coating. The holes are inclined with an angle of 30°. Two different configurations are investigated that differ in the shaping of the holes in their outlet region. The numerical investigation focus on the influence of different turbulence models on the results. Regarding the secondary flow, the cooling film development and complex jet mixing vortex systems are analyzed. Additionally, the impact on the temperature distribution both on the plate surface and in the plate is investigated. It is shown that the choice of the turbulence model has a significant influence on the prediction of the flow structure, and, consequently, on the calculation of the thermal load of the solid body.

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Revealing Mechanical Strength of Nanopores Using Atomic Finite Element Techniques

Materials Science Forum ◽

10.4028/www.scientific.net/msf.934.24 ◽

2018 ◽

Vol 934 ◽

pp. 24-29

Author(s):

Prapasiri Pongprayoon ◽

Attaphon Chaimanatsakun

Keyword(s):

Mechanical Properties ◽

Finite Element Method ◽

Finite Element ◽

Fluid Flow ◽

Mechanical Strength ◽

Impact Force ◽

Pore Surface ◽

Vertical Rectangle ◽

The Impact ◽

Graphene Nanopore

Graphene nanopore has been widely employed in nanofilter or nanopore devices due to its outstanding properties. The understanding of its mechanical properties at nanoscale is crucial for device improvement. In this work, the mechanical properties of graphene nanopore is thus investigated using atomistic finite element method (AFEM). Four graphene models with different pore shapes (circular (CR), horizontal rectangle (RH), and vertical rectangle (RV)) in sub-nm size which could be successfully fabricated experimentally have been studied here. The force normal to a pore surface is applied to mimic the impact force due to a fluid flow. Increasing pore size results in the reduction in its strength. Comparing among different pore shapes with comparable sizes, the order of pore strength is CR>RH>RV>SQ. In addition, we observe that the direction of pore alignment and geometries of pore edge also play a key role in mechanical strength of nanopores.

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Installation of submarine cables and pipes in shallow waters and connecting them to the shore by the method of horizontal directional drilling

E3S Web of Conferences ◽

10.1051/e3sconf/202128604007 ◽

2021 ◽

Vol 286 ◽

pp. 04007

Author(s):

Valeriu-Florian Vasilescu ◽

Dumitru Dinu

Keyword(s):

Marine Environment ◽

Offshore Wind ◽

Shallow Waters ◽

Directional Drilling ◽

Horizontal Directional Drilling ◽

Negative Effects ◽

Subsea Tunnel ◽

Submarine Cables ◽

Wind Energy Systems ◽

The Impact

This article presents the horizontal directional drilling (HDD) as one of the most suitable technique used to reduce the impact on the environment during the submarine pipe and cable installation process, especially in the coastal area and shallow waters. HDD is a technique used to drill a subsea tunnel or under other designated area with the goal to pull a pipe or other facility through the drilled underground tunnel. With the development of the offshore natural gas and wind industry, the demand for the construction of transfer pipeline and cables has also increased. The installation of submarine pipelines and cables can have negative effects on the marine environment. This is one of the main reasons that construction and operation of offshore wind energy systems has been and continues to be regarded with scepticism by environmental activists, despite the undeniable benefits of this renewable energy source. The main objectives of this article are to emphasize the importance of using this technique but also to highlight the benefits, in particular by significantly reducing the impact on the marine environment.

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Multicomponent multiphase reactive fluid flow in viscoelastoplastic porous media: localization patterns of fluid flow and strain

10.5194/egusphere-egu21-15478 ◽

2021 ◽

Author(s):

Lyudmila Khakimova ◽

Nikolai Belov ◽

Artyom Myasnikov ◽

Anatoly Vershinin ◽

Kirill Krapivin ◽

...

Keyword(s):

Fluid Flow ◽

Reactive Transport ◽

Transport Model ◽

Shear Bands ◽

Porous Matrix ◽

Deformation Localization ◽

Linear Free Energy ◽

Constrained Minimization Problem ◽

Spectral Finite Elements ◽

The Impact

This work is devoted to developing the self-consistent thermo-hydro-chemo-mechanical reactive transport model to predict and describe natural and industrial petroleum processes at different scales.We develop a version of the front tracking approach for multicomponent multiphase flow in order to treat spontaneous splitting of discontinuities. We revisit the solution for the Riemann problem and systematically classify all possible configurations as functions of initial concentrations on both sides of the discontinuity. We validate the algorithm against finite volume high-resolution technics and high-order spectral finite elements.To calculate the parameters of phase equilibria, we utilize an approach based on the direct minimization of the Gibbs energy of a multicomponent mixture. This method ensures the consistency of the thermodynamic lookup tables. The core of the algorithm is the non-linear free-energy constrained minimization problem, formulated in the form of a linear programming problem by discretization in compositional space.The impact of the complex rheological response of porous matrix on the morphology of fluid flow and shear deformation localization is considered. Channeling of porosity waves and shear bands morphology and their orientation is investigated for viscoelastoplastic both shear and bulk rheologies.

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THE IMPACT OF SELECTED PARAMETERS ON PRESSURE DISTRIBUTION IN THE FACE THROTTLE OF A CENTRIFUGAL PUMP AUTOMATIC BALANCING DEVICE

Tribologia ◽

10.5604/01.3001.0015.6895 ◽

2021 ◽

Vol 297 (3) ◽

pp. 35-44

Author(s):

Yuliia Tarasevych ◽

Nataliia SOVENKO

Keyword(s):

Fluid Flow ◽

Pressure Distribution ◽

Hydrodynamic Pressure ◽

Centrifugal Pumps ◽

Unsteady Fluid Flow ◽

The Face ◽

Unsteady Fluid ◽

Angular Displacements ◽

Automatic Balancing ◽

The Impact

Face throttles are a necessary functional element of non-contact face seals and automatic balancing devices of centrifugal pumps of different constructions. To calculate the hydrodynamic forces and moments acting on the rotor and fluid flow through the automatic balancing device, it is necessary to know the pressure distribution in the cylindrical and face throttle when considering all important factors which predetermine fluid flow. The face throttle surfaces are moving, which leads to unsteady fluid flow. The movement of the walls of the face throttle causes an additional circumferential and radial flow, which subsequently leads to the additional hydrodynamic pressure components. The paper analyses viscous incompressible fluid flow in the face throttle of an automatic balancing device taking into account the axial and angular displacements of throttle’s surfaces and the inertia component of the fluid. The effect of local hydraulic losses as well as random changes in the coefficients of local hydraulic resistance at the inlet and outlet of the throttle is analysed.

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