Amir Raoof

Utrecht University | UU · Department of Earth Sciences

Skeletonization, a crucial step in pore network modeling, traditionally involves the extraction of skeleton pixels from binarized, segmented X-ray images of porous materials. However, this conventional approach often suffers from user bias during segmentation, potentially leading to the loss of essential image details. This study addresses this lim...

Object detection and tracking are vital in computer vision and visual surveillance, allowing for the detection, recognition, and subsequent tracking of objects within images or video sequences. These tasks underpin surveillance systems, facilitating automatic video annotation, identification of significant events, and detection of abnormal activiti...

The image illustrates the direct observation of trapped high-salinity water expansion at a microscopic scale and its contribution to the oil movements after 70 hours of continuous monitoring.

This study proposes an artificial intelligence approach to assess watershed morphometry in the Makran subduction zones of South Iran and Pakistan. The approach integrates machine learning algorithms, including artificial neural networks (ANN), support vector regression (SVR), and multivariate linear regression (MLR), on a single platform. The study...

A water supply is vital for preserving usual human living standards, industrial development, and agricultural growth. Scarce water supplies and unplanned urbanization are the primary impediments to results in dry environments. Locating suitable sites for artificial groundwater recharge (AGR) could be a strategic priority for countries to recharge g...

In recent decades, there has been a growing emphasis on assessing aquifer vulnerability. Given the availability of spatial data and the GIS advantages, mapping the groundwater vulnerability has become a common tool for protecting and managing groundwater resources. Here, we applied the GIS indexing and an overlay method to explore a combination of...

Numerous mechanisms have been proposed to untangle the effect of a low concentration of dissolved salts in the water flooding medium. One potential mechanism for enhanced oil movement is proposed with osmosis effect, however, the process of water transport through the oil phase, due to a salinity contrast, is not fully understood. In our study, we...

Because of their extreme heterogeneity at multiple scales, carbonate rocks present a great challenge for studying and managing oil reservoirs. Depositional processes and diagenetic alterations of carbonates may have produced very complex pore structures and, consequently, variable fluid storage and flow properties of hydrocarbon reservoirs. To unde...

The dropping of the water level of the lakes located in the arid lands leads to salt concentration increase. In this study, a combined experimental-computational method is developed to explore the effect of seawater concentration on the elevation of groundwater table and the rate of saltwater intrusion, while the lake water level is dropping. At th...

In dissolution processes, during geometry evolution, the two-phase interface is continuously changed. For tracking the position of the interface, the method of combining VOF with curved boundary schemes was presented in this research. Since the combination would be rather complex, in addition to the original approach, a simplified approximate appro...

Colloid transport through a porous medium changes geometrical and hydraulic properties of the pore space. The impact of this effect depends on the colloid types and pore space surface properties which determine the likelihood of pore clogging. Colloid attachment and subsequent detachment are key factors in pore clogging. In this study, the impact o...

Release of colloids and their subsequent transport into the subsurface environments takes place during a wide range of applications such as industrial, energy storage, and agricultural activities. Therefore, processes contributing to transport, attachment, and re-mobilization of colloids in porous media are attracting attention. A fraction of the r...

The numerical modelling of ionic diffusive transport through a charged thin film of electrolyte is mathematically and computationally complex due to the strongly coupled hydrodynamics and electrochemical interactions. Generally, simulations are performed by solving the Poisson equation together with the Nernst-Planck flux formula to model electroch...

Pore network model simulation (PNM) is an important method to simulate reactive transport processes in porous media and to investigate constitutive relationships between permeability and porosity that can be implemented in continuum-scale reactive-transport modelling. The existing reactive transport pore network models (rtPNMs) assume that the init...

Implementation of nonlinear boundary conditions like nth-order surface reactions or surface radiation heat transfer has not been investigated in lattice Boltzmann (LB) framework. This study presents a novel kinetic level method for their implementation. The method couples Taylor expansion of the conditions with counter-slip approach to find unknown...

This study focuses on the effects of soil textural heterogeneity on longitudinal dispersion under saturation conditions. A series of solute transport experiments were carried out using saturated soil columns packed with two filter sands and two mixtures of these sands, having d 50 values of 95, 324, 402, and 480 µm, subjected to four different stea...

A major contaminant transport process in soils is hydrodynamic dispersion by affecting the spreading and arrival of surface-applied pollutants at underlying groundwater reservoirs. When a soil is unsaturated, hydrodynamic dispersion is very much affected by soil water saturation. Centimeter- and decimeter-scale column experiments were carried out t...

In this study, the complexity of a steady-state flow through porous media is revealed using confocal laser scanning microscopy (CLSM). Micro-particle image velocimetry (micro-PIV) is applied to construct movies of colloidal particles. The calculated velocity vector fields from images are further utilized to obtain laminar flow streamlines. Fluid fl...

The pore structure of many carbonate formations is known to be very complex and heterogeneous. Heterogeneity is manifested by the presence of different types, sizes, and shapes of pores resulting from sedimentation and diagenetic actions. These complexities greatly increase uncertainties in estimated rock hydraulic properties in that different perm...

Low-salinity water flooding can be effectively used for enhanced oil recovery. Given the complex physical and chemical processes involved, several controlling mechanisms have been proposed to describe oil re-mobilization in the presence of water solution with low salinity. Osmosis and water-in-oil emulsification are among these mechanisms. However,...

Predicting the solute dispersivity in porous media is complicated by the known scale dependency of dispersion processes. In this study, we combined three complementary methods to investigate solute dispersivity at different length scales. The applied methods included 36-cm long column experiments, extremely large three-dimensional (3D) X-ray image-...

The Q-slope system is an empirical method for discontinuous rock slope engineering classification and assessment. It has been introduced recently to provide an initial prediction of rock slope stability assessment by applying simple assumptions which tend to reflect different failure mechanisms. This study offers a correlation relationship between...

In the present study, in Zarand district, Kerman province, Iran, we used a Geological Information System (GIS) to explore the relationship between the situation of coal mines, the drainage patterns, the topographic state of the district, the presence increased fluoride levels in ground water, and the prevalence of dental fluorosis. We found a stron...

Petrophysical properties of rocks at reservoir scales are of great importance to the oil and gas industry, particularly for exploration, production and recovery purposes. However, running field-scale tests are expensive and time-consuming. Accordingly, the continuum scale is frequently used to represent the heterogeneous structure of rocks. This st...

Carbonate rocks host several large water and hydrocarbon reservoirs worldwide, some of them highly heterogeneous involving complex pore systems. Pre-salt reservoirs in the Santos Basin off the south-east coast of Brazil, are an example of such rocks, with much attention focused on proper characterization of their petrophysical and multiphase flow p...

In order to increase oil recovery from a reservoir, it is important to analyse adequate petrophysical description of rocks at different scales and perspectives. As large-scale tests demand time and are highly costly, being able to mimic field properties from laboratory measurements has shown to be a promising and feasible alternative in terms of re...

Aquifers are a major source of freshwater in many parts of the world. Saltwater intrusion from the sea or saline lakes into freshwater aquifers degrades the potable quality of these resources. Various methods have been introduced to mitigate saltwater intrusion, such as recharge wells and physical subsurface barriers. This paper presents an alterna...

A two-pressure dynamic drainage algorithm is developed for three-dimensional unstructured network model. The impact of time step is discussed through drainage simulations. Dynamic effects in average phase pressure for fluid phases with different viscosity ratios are explored using the developed code as an upscaling tool. For cases where two fluids...

Liquid penetration into thin porous media such as paper is often simulated using continuum-scale single-phase Darcy's law. The underlying assumption was that a sharp invasion front percolates through the layer. To explore this ambiguous assumption and to understand the controlling pore-scale mechanisms, we have developed a dynamic pore-network mode...

This data article provides a precise level data on alluvial fans of the western border of Lut desert, a unique location on the Earth, known as one of the hottest spot on the Earth. This data is essential for morphotectonic investigations and is valuable in the field of tectonic and geomorphology studies. It helps to evaluate the region from the vie...

Two-phase flow in three porous media with different geometry complexities are simulated using the Volume-of-Fluid (VOF) method. The evolution of the flow pattern, as well as the dynamics involved are simulated and compared to experiments. For a simple geometry and smooth solid surface, like single capillary rise experiment, VOF simulation gives res...

The production of natural gas from the gas hydrates has attracted significant attention over the last few decades. A continued challenge in gas hydrates is the estimation of the stored gas capacity. To alleviate this problem, this study uses the numerical modeling to provide insight into the distribution of hydrate in porous media and to obtain inf...

The macroscopic effects of soil textural heterogeneity and fine-scale soil layering on unsaturated flow remain poorly understood. In this study we used the Discrete Element Method (DEM) to numerically generate artificial particle packings of heterogeneous sands from which the pore structure can be extracted. Packings were generated from known grain...

In this study, the spreading of a liquid droplet on the surface of a fibrous paper and its penetration into the paper is studied. The spreading of the droplet was visualized using confocal microscopy and the penetration depth was quantified using Automatic Scanning Absorptiometry (ASA) measurements. The three-dimensional structure of the paper was...

Flow of the contaminated water through membrane causes fouling and leads to change membrane transport properties. Understanding how membrane hydraulic properties change during the operation is critical for evaluating the performance of membrane and helps to improve their design. In this study, a 3D pore network model is developed to simulate the re...

Modeling morphological and hydraulic properties of thin porous media, such as filter layers and papers is highly relevant to various industries. In our previous studies, the X-ray tomography and FIB-SEM methods were applied to capture micro- and nano-scale pores in uncoated paper and coated layer, respectively. Here, the reconstructed pore structur...

In this paper the main criteria of the water curtain system for unlined rock caverns (URCs) is described. By the application of numerical modeling and genetic programming (GP), a method for water curtain system pre-design for Iranian crude oil storage URCs (common dimension worldwide) is presented. A comprehensive set of numerical simulations is pe...

Supplementary Material for "Meter-scale reactive transport modeling of CO2-rich fluid flow along debonded wellbore casing-cement interfaces", Evironmental Science & Technology 52, 6, 3786–3795 - https://doi.org/10.1021/acs.est.7b05358

Defects along wellbore interfaces constitute potential pathways for CO2 to leak from geological storage systems. In previous experimental work, we demonstrated that CO2-induced reaction over length-scales of several meters can lead to self-sealing of such defects. In the present work, we develop a reactive transport model that, on the one hand, ena...

The current study provides new experimental data on nonlinear flow behavior in various uniformly graded granular materials (20 samples) ranging from medium sands (d50>0.39 mm) to gravel (d50=6.3 mm). Generally, theoretical equations relate the Forchheimer parameters a and b to the porosity, as well as the characteristic pore length, which is assume...

The production of liquid water in cathode catalyst layer, CCL, is a significant barrier to increase the efficiency of proton exchange membrane fuel cell. Here we present, for the first time, a direct three-dimensional pore-scale modelling to look at the complex immiscible two-phase flow in CCL. After production of the liquid water at the surface of...

Many environmental and agricultural applications involve the transport of water and dissolved constituents through aggregated soil profiles, or porous media that are structured, fractured or macroporous in other ways. During the past several decades, various process-based macroscopic models have been used to simulate contaminant transport in such m...

Paper used in the printing industry generally contains a relatively thin porous coating covering a thicker fibrous base layer. The three-dimensional pore structure of coatings has a major effect on fluid flow patterns inside the paper medium. Understanding and quantifying the flow properties of thin coating layers is hence crucial. Pore spaces with...

Transport and deposition of nanoparticles in porous media is a multi-scale problem governed by several pore-scale processes, and hence, it is critical to link the processes at pore scale to the Darcy-scale behavior. In this study, using pore network modeling, we develop correlation equations for deposition rate coefficients for nanoparticle transpo...

The performance of a proton exchange membrane fuel cell, PEMFC, is significantly affected by the rate of oxygen diffusion through the cathode catalyst layer, CCL. Continuum-scale modelling of PEMFCs requires knowledge of the effective oxygen diffusivity as a function of CCL porosity and its water saturation. To provide this functionality, we used t...

In this study we performed batch experiments to investigate the dissolution kinetics of trichloroethylene (TCE) and toluene vapors in water at room temperature and atmospheric pressure. The batch systems consisted of a water reservoir and a connected headspace, the latter containing a small glass cylinder filled with pure volatile organic compound...

Debonding at casing-cement interfaces poses a leakage pathway risk that may compromise well integrity in CO2 storage systems. The present study addresses the effects of long-range, CO2-induced, reactive transport on the conductance of such interfacial pathways. This is done by means of reactive flow-through experiments, performed on simulated wellb...

Core Ideas A discrete element model was used to extract the pore structure of particle packings. Soil grain compaction and size mixing affect pore structure. Size mixing had a greater effect than compaction on the pore size distribution. Compaction caused the SWRCs to change uniformly with porosity. Compaction decreased the van Genuchten α paramete...

Core Ideas A recent laboratory experiment of horizontal water redistribution was simulated. Two different models were separately used to reproduce the measured data. Interfacial area model results showed better agreement with experimental data. When two soil samples with the same hydraulic properties but different initial water saturations are bro...

The temperature inside wells used for gas, oil and geothermal energy production, as well as steam injection, is in general significantly higher than the groundwater temperature at shallower depths. While heat loss from these hot wells is known to occur, the extent to which this heat loss may result in density-driven flow and in mixing of surroundin...