Plume Movement Research Articles

Modelling Plume Development with Annual Pulses of Contaminants Released from an Airport Runway to a Layered Aquifer, Evaluation of an In Situ Monitoring System

In cold climates, the use of de-icing chemicals in the winter can lead to groundwater contamination, especially when used in large quantities, such as at airports. Oslo Airport, Gardermoen, is situated on Norway’s largest rain-fed aquifer. Potassium formate is used to remove ice from runways and propylene glycol from airplanes; the organic parts are degradable. Most of the wells to monitor the spread of de-icing chemicals in the underlying aquifer have well screens near the groundwater level, while the runways and the source of de-icing chemicals are near the groundwater divides, where vertical flow is expected. The objective of this study is to demonstrate the importance of layers and time-varying recharge on the spreading of contaminant plumes in an aquifer near a groundwater divide. This is done with numerical modelling. The model results show increased vertical transport of the added tracer in the presence of horizontal layers, both continuous and discontinuous, in the aquifer. With certain distributions of hydraulic conductivity, Ks, we demonstrate that deeper monitoring wells are required. With the scenarios modelled here, time-varying recharge has a weaker effect on plume distribution. Measured concentrations of potassium and total organic carbon show the cyclic effect of seasonally varying recharge of contaminants, and an asymptotic accumulation of concentration over time, that is consistent with the model runs. In conclusion, groundwater monitoring systems near a groundwater divide should include multi-level samplers to ensure control of the vertical plume movement.

Two‐Dimensional Modeling of Colloid‐Facilitated Contaminant Transport in Groundwater Flow Systems With Stagnant Zones

AbstractA mathematical model has been developed for the contaminant transport with colloids in groundwater flow systems with stagnant zones to investigate the effect of stagnant zones on the transport of contaminants with colloids. In the present study, colloids and contaminants are supposed to drift via two coexisting homogeneous regions. The critical limitation of the mobile‐immobile (MIM) model is to deal with the number of parameters used upon application to larger scales for both mobile and immobile regions when a series of transport mechanisms are involved. Therefore, the present model is the first attempt model of the equilibrium approach for mobile‐immobile regions to avoid complexities in the model. The present study includes the effect of the stagnant zone on the plume movement in mobile regions for steady‐state flow conditions, and it is discerned that the plume moves faster in the presence of immobile regions. However, when dispersion, velocity, and pulse duration are decreased, tailing is noticed in the breakthrough profiles. Stagnant regions enhance the transport of contaminants in the porous media and produce augmented breakthrough curves by increasing the velocity in the mobile regions where colloids and contaminants migrate simultaneously. The transport of contaminants can be enhanced in the presence of colloids. However, sensitivity analyses indicate that the combination of different distribution coefficients controls the mobility of contaminants even in the presence of colloids. The proposed model has been validated using experimental data of the single‐porosity model in the presence of colloids and the MIM model in the absence of colloids.

LEACHATE TRANSPORT PHENOMENON ON GROUNDWATER QUALITY: MODELING USING MODFLOW AND MT3DMS TOOLS

<p>The dumping of solid waste in uncontrolled landfills can cause significant impacts on the environment and human health. The open dumps cause the formation of leachate which contaminated the groundwater; use of these groundwater reported danger to the human health. The goal of groundwater protection is necessary to control the release and migration of pollutants from the leachate in the subsurface. In this paper, the above-mentioned problems were dealt with the case study of Ariyamangalam open dumping site, Tiruchirappalli, Tamilnadu. The dump site receives 71% of organic waste. The groundwater flow and leachate transport model was developed using Visual MODFLOW and MT3DMS (Version 4.3), to study the leachate transport in the subsurface and to predict the plume behavior under different scenarios. The conceptual model of the system was derived from the information on geology, geo physical and geo hydrology of the study area. The total dissolved solids (TDS) were taken as a parameter, to study the extent of contaminant plume for the next nine years (2014-2022). From the groundwater flow model, it was found that the increase in water level by 2.5 m above MSL from December 2010 (70.9 m above MSL) to December 2022 (73.4 m above MSL) around the study area. From the leachate transport model, the predicted TDS plume movement was identified towards the west and south east directions of the open dumping area. As a conclusion, the developed groundwater flow and leachate transport model can be effectively used for studying the leachate migration from the open dumping site into subsurface system.</p>

Modelling of sediment plume associated with the capital dredging for sustainable mangrove ecosystem in the Old Mangalore Port, Karnataka, India

Old Mangalore port is located at the Confluence of River Gurpur and Netravathi in the Mangalore District, Karnataka. The Ministry of Shipping has promoted the modernisation of ports, including the Old Mangalore port, under the Sagarmala Project. The Old Mangalore port’s navigational channel is approximately 3.2 km long and 80 m wide. It is proposed to deepen the existing approach channel to 7 m to allow medium-capacity vessels access to the port. The expected quantity of dredging is estimated to be 1160000 m3. We investigated the sediment spill plume movement of the dredging/dumping operations at Old Mangalore port using FVCOM (Finite Volume Community Ocean Model). Analysis showed that the spill plume was moved towards the offshore direction during the wet season and is primarily dictated by the prevailing currents and freshwater influx from the rivers. During the dry season (minimal discharge), the plume spreads approximately 8 km to the upstream regions and is mainly controlled by tidal currents. The study also revealed that the dumping point at a distance of 18–20 km offshore (depth > 20 m) is ideal for the optimum settling of the sediments for both seasons. The capital dredging of a navigational channel and construction of a new coastal berth is a one-time operation. Any siltation of the river mouth during the dry season will likely be flushed out in the subsequent wet season. We identified 12 types of mangrove species in the vicinity of the dredging area, and mangroves near the Old Mangalore port may be more exposed to the dredging activities impacts. Spillage during the dredging produces the sediment plume, and its transport to the mangrove region may choke the root system, thereby reducing oxygen availability. Hence, the study recommends that dredging operations can be carried out at any season but restricted to the ebb tide, thereby preventing the movement of sediment plumes to the mangrove region and thus conserving the mangrove ecosystem.

Larval dispersal of Brachyura in one of the largest estuarine/marine systems in the world.

The Amazon Continental Shelf (ACS) is a complex habitat that receives a large annual freshwater discharge into the ocean, producing a superficial plume and carrying with it large amounts of nutrients to the continental shelf along thousands of kilometers while sustaining high biodiversity in the estuary-ocean continuum. For the first time, this study monitored six sites in a wide transect with approximately 240 km radius on the ACS every 2-4 months. The objectives were (1) to analyze the composition of larval Brachyuran crabs and (2) to predict the importance of environmental parameters (temperature, salinity and chlorophyll-a) in structuring their abundance. A total of 17,759 larvae identified were distributed in 8 families and 24 taxa. The water salinity was the best predictor of larval distribution. The statistical models used indicated that Panopeidae and Portunidae larvae are more frequent and more likely to occur in shallow water layers, while Calappidae occur in deeper layers, and Grapsidae, Ocypodidae, Sesarmidae, Pinnotheridae and Leucosiidae occur similarly in both strata. The larval dispersal extent varies among families and throughout the year while the groups are distributed in different salinities along the platform. The probability of occurrence of Portunidae is higher in ocean water (≥ 33.5); Grapsidae, Panopeidae, and Pinnotheridae is higher in intermediate and ocean salinity waters (25.5 to 33.5); Ocypodidae, Sesarmidae and Calappidae is higher in estuarine and intermediate salinity waters (5 to 25.5), whereas Leucosiidae, euryhaline, occur in all salinities (5 to 33.5). Furthermore, the Amazon River seasonal flow and plume movement throughout the year not only regulate the larval distribution and dispersion of estuarine species but are also fundamental for the ACS species, providing the necessary nutrient input for larval development in the region.

TRACKING THE GODZILLA DUST PLUME USING GOOGLE EARTH ENGINE PLATFORM

Abstract. As part of Earth’s nutrient cycle, a layer of air travels every summer from Africa across the Atlantic Ocean. In June 2020, the thickest and densest dust plume traveled over 5000 miles along with the Saharan Air Layer (SAL) from Africa towards the USA and the Caribbean. Due to its gravity and impact, it was nicknamed “Godzilla”. While the cause of this event remains unclear, the advantage of using remote sensing applications to monitor aerosol concentrations and movement provides future opportunities to leverage machine learning technologies to build predictive models with the goal of early forecasting and public health interventions. The Sentinel-5P satellite instrument measures the air quality, ozone, and Ultraviolet (UV) radiation, and can be used for climate monitoring, and forecasting. Available on this platform is the UV Aerosol Index (AI) product, a qualitative index that indicates the presence of elevated layers of aerosols in the atmosphere. In this paper, we used Google Earth Engine to monitor the transatlantic movement of this historic dust plume across the Sahara Desert and estimate the aerosol concentrations throughout June 2020. The flexibility of the platform enabled us to generate time series maps to visualize the movement of the Godzilla dust storm from the Sahara Desert across the ocean. The results obtained are relevant for effective planning and interventions to ameliorate the health threats associated with the movement of the dust plume. The outcome is useful for defining the relationship between aerosol concentrations, human health, and aquatic life.

Neutron Response Modeling to Track Lean Gas Plume in Recycled Gas Cap Reservoir in Concurrent Gas Cap-Oil Rim Development: A Step Forward

Summary Gas cap pressure maintenance while developing the associated oil rim is a critical aspect for optimum recovery. Preventing gas cap pressure dropping below dewpoint by injecting lean gas is essential for concurrent gas cap-oil rim development. Reservoir heterogeneity aggravates lean gas override causing preferential movement of lean gas plume. Thus, it is important to track lean gas plume while recycling and understanding the breakthrough potential of lean gas. This paper demonstrates a new workflow to track lean gas plume by estimating phase saturations with a case study from one of the giant oil and gas fields, Onshore, Abu Dhabi. Pulsed neutron capture (PNC) tools are used for reservoir monitoring and surveillance. However, sigma log evaluation is insufficient to derive individual hydrocarbon phase saturations to monitor lean gas plume. Neutron response modeling (NRM) is devised to differentiate between lean and rich gas. NRM is a probabilistic solver with input of mineral and fluid phase parameters into tool response functions in petrophysical evaluation. To distinguish with discrete neutron fluid response between lean and rich gas, pressure/volume/temperature (PVT) data are utilized to derive hydrogen index, capture cross section, thermal decay length, and neutron macro parameters, such as neutron slowing down length and migration length. Neutron response is investigated for lean and rich gas with sensitivity of invasion effects on neutron log by calibrating to core porosity. The response for each phase under thermal neutron and capture modes with corresponding raw neutron log statistics is reviewed in both openhole and casedhole environments in known lean/rich gas intervals. Thirty-five wells spread across gas cap and oil leg with quality neutron log data are modeled and individual phase saturations are estimated. The target reservoir is under development with over three decades of lean gas injection to support oil production. NRM results and phase saturations are validated with recent formation sampling, which enhanced the confidence in the overall workflow. Later, the results are verified to be in excellent agreement with lean gas injection and production history of the target reservoir. The identified movement of lean gas highlights nonuniform geology and gravity segregation of injected lean gas into upper members of the target reservoir. The results also emphasized the need for better injection support to lower members of the target reservoir where gas cap development is ongoing. The solution presented is unique, particularly for lean gas injection projects by utilizing PVT for NRM based on neutron transport mechanism in pore fluids. Existing workflows require a special nuclear modeling platform with computationally expensive processing on data sets acquired using advanced logging technology. In spite of these prerequisites, existing workflows are not able to distinguish lean gas over rich gas. This paper effectively demonstrates NRM workflow distinguishing lean gas plume from rich gas using neutron logs and reveals compelling reservoir management insights. The sensitivity studies and practicality of this workflow highlight the fundamental importance of neutron logs in mature fields.

Unsteady Flow Oscillations in a 3-D Ventilated Model Room with Convective Heat Transfer

Improving indoor air quality and energy consumption is one of the high demands in the building sector. In this study, unsteady flow oscillations in a 3-D ventilated model room with convective heat transfer have been studied for three configurations of an empty room (case 1), a room with an unheated box (case 2) and a room with a heated box (case 3). Computational results are validated against experimental data of airflow velocity, temperature and turbulence kinetic energy. For each case, flow unsteadiness is presented by the time history of airflow velocity and temperature at prescribed monitor points and further analyzed using the Fast Fourier Transform technique. For case 1, the flow oscillation is irregular and less dependent on the monitor points. For case 2, the flow oscillation is still irregular but with increased frequency, possibly due to enhanced flow recirculation around the corners of the unheated box. For case 3, a dominant frequency exists, and thermal energy oscillating is higher than flow kinetic energy. Among the three cases, case 3 has the highest dominant frequency in a range of 4.3–4.6 Hz, but the kinetic energy is the lowest at 1.25 m2⁄s. The unsteady flow oscillation is likely due to a high Grashof number and corner flow recirculation for cases 1 and 2, and a combination effect of a high Grashof number, corner flow recirculation and thermal instability (induced by the formation and movement of the thermal plume) for case 3.

Thermodynamic characterization of H2-brine-shale wettability: Implications for hydrogen storage at subsurface

Large-scale underground hydrogen storage (UHS) appears to play an important role in the hydrogen economy supply chain, hereby supporting the energy transition to net-zero carbon emission. To understand the movement of hydrogen plume at subsurface, hydrogen wettability of storage rocks has been recently investigated from the contact angles rock-H2-brine systems. However, hydrogen wettability of shale formations, which determines the sealing capacity of the caprock, has not been examined in detail. In this study, semi-empirical correlations were used to compute the equilibrium contact angles of H2/brine on five shale samples with various total organic content (TOC) at various pressures (5–20 MPa) and at 343 K. The H2 column height that can be securely trapped by the shale and capillary pressures were calculated. The shale's H2 sealing capacity decreased with increasing pressure, increasing depth and TOC values. The CO2/brine equilibrium contact angles were generally higher than H2/brine equilibrium, suggesting that CO2 could be used as favorable cushion gas to maintain formation pressure during UHS. The utmost height of H2 that can be safely trapped by shale 3 (with TOC of 23.4 wt%) reduced from 8950 to 8750 M while that of shale 5 (with TOC of 0.081 wt%) reduced slightly from 9100 M to 9050 M as the pressure was increased from 5 to 20 MPa. The capillary entry pressure decreased with increasing depth and shale TOC, implying that the capillary trapping effect, as well as the over-pressure required to move brines from the pores by hydrogen displacement, reduces with increasing depth, and shale TOC. However, the shales remained at strongly water-wet conditions, having an equilibrium contact angles of not more than 17° at highest pressure and TOC. The study suggests that the increasing contact angles with increasing pressure and shale TOC, as well as decreasing column height and capillary pressure with increasing depth for H2-brine-shale systems might not be sufficient to exert significant influence on structural trapping capacities of shale caprocks due to low densities of hydrogen.

Impacts of Future Climate Variability on Atrazine Accumulation and Transport in Corn Production Areas in the Midwestern United States.

Atrazine is one of the most prevalent herbicides that has been widely applied to agricultural lands in the U.S. Understanding the transport and accumulation of atrazine in the subsurface under future climate scenarios is essential for future agriculture and water management. Here, we predict atrazine transport and accumulation under an intensive corn production land based on 20 projected global climate model (GCM) realizations, while considering uncertainties of transport parameters. Our study predicted continuous groundwater table declination and atrazine mass accumulation on the study site. We show that atrazine mass accumulation in corn production areas is subject to total precipitation in the atrazine application season, whereas atrazine plume movement is controlled by the sequence of annual precipitation. Atrazine mass transport and accumulation are more sensitive to climate variation on the field sites with low sorption and atrazine degradation rate. Under the extreme condition, the atrazine plume can migrate as far as five meters from the ground surface in only three years. While annual mean precipitation in the Midwestern U.S. is projected to increase in the future, groundwater vulnerability to atrazine and associated water quality impacts may rise in the U.S. Corn Belt, especially in sites with low atrazine degradation and sorption.

Can Forel–Ule Index Act as a Proxy of Water Quality in Temperate Waters? Application of Plume Mapping in Liverpool Bay, UK

The use of ocean colour classification algorithms, linked to water quality gradients, can be a useful tool for mapping river plumes in both tropical and temperate systems. This approach has been applied in operational water quality programs in the Great Barrier Reef to map river plumes and assess trends in marine water composition and ecosystem health during flood periods. In this study, we used the Forel–Ule colour classification algorithm for Sentinel-3 OLCI imagery in an automated process to map monthly, annual and long-term plume movement in the temperate coastal system of Liverpool Bay (UK). We compared monthly river plume extent to the river flow and in situ water quality data between 2017–2020. The results showed a strong positive correlation (Spearman’s rho = 0.68) between the river plume extent and the river flow and a strong link between the FUI defined waterbodies and nutrients, SPM, turbidity and salinity, hence the potential of the Forel–Ule index to act as a proxy for water quality in the temperate Liverpool Bay water. The paper discusses how the Forel–Ule index could be used in operational water quality programs to better understand river plumes and the land-based inputs to the coastal zones in UK waters, drawing parallels with methods that have been developed in the GBR and Citclops project. Overall, this paper provides the first insight into the systematic long-term river plume mapping in UK coastal waters using a fast, cost-effective, and reproducible workflow. The study created a novel water assessment typology based on the common physical, chemical and biological ocean colour properties captured in the Forel–Ule index, which could replace the more traditional eutrophication assessment regions centred around strict geographic and political boundaries. Additionally, the Forel–Ule assessment typology is particularly important since it identifies areas of the greatest impact from the land-based loads into the marine environment, and thus potential risks to vulnerable ecosystems.

Research on the smoke mass flow rate in one-dimensional spreading stage in tunnel with multiple fire sources

The toxic high-temperature fire smoke plume in tunnel fire will seriously threaten the safety of personnel and tunnel structure. Therefore, it is very important to study the fire smoke plume movement law in tunnel fire for controlling and exhausting smoke. However, previous studies mainly focused on single fire source. In fact, most of the catastrophic fires have multiple fire sources. When multiple fires burn at the same time, the competitive entrainment air will cause the flame to tilt and even merge with each other, which will increase the burning rate and accelerate the spread of the fire. In this paper, the influence of fire heat release rate and distance between fires on fire smoke plume generation in tunnel is studied by a series of numerical simulations. The investigation results show that when the spacing is non-zero, the fire smoke plume generation rate is greater than that when the spacing is zero, because of the additional entrainment region. The fire smoke plume generation rate increases with HRR in spreading stage tunnel fire. In addition, a prediction model considering the heat release rate and burner edge spacing is proposed.

Monitoring geological storage of CO2 using a new rock physics model

To mitigate the global warming crisis, one of the effective ways is to capture CO2 at an emitting source and inject it underground in saline aquifers, depleted oil and gas reservoirs, or in coal beds. This process is known as carbon capture and storage (CCS). With CCS, CO2 is considered a waste product that has to be disposed of properly, like sewage and other pollutants. While and after CO2 injection, monitoring of the CO2 storage site is necessary to observe CO2 plume movement and detect potential leakage. For CO2 monitoring, various physical property changes are employed to delineate the plume area and migration pathways with their pros and cons. We introduce a new rock physics model to facilitate the time-lapse estimation of CO2 saturation and possible pressure changes within a CO2 storage reservoir based on physical properties obtained from the prestack seismic inversion. We demonstrate that the CO2 plume delineation, saturation, and pressure changes estimations are possible using a combination of Acoustic Impedance (AI) and P- to S-wave velocity ratio (Vp/Vs) inverted from time-lapse or four-dimensional (4D) seismic. We assumed a scenario over a period of 40 years comprising an initial 25 year injection period. Our results show that monitoring the CO2 plume in terms of extent and saturation can be carried out using our rock physics-derived method. The suggested method, without going into the elastic moduli level, handles the elastic property cubes, which are commonly obtained from the prestack seismic inversion. Pressure changes quantification is also possible within un-cemented sands; however, the stress/cementation coefficient in our proposed model needs further study to relate that with effective stress in various types of sandstones. The three-dimensional (3D) seismic usually covers the area from the reservoir's base to the surface making it possible to detect the CO2 plume's lateral and vertical migration. However, the comparatively low resolution of seismic, the inversion uncertainties, lateral mineral, and shale property variations are some limitations, which warrant consideration. This method can also be applied for the exploration and monitoring of hydrocarbon production.

Experimental and Numerical Study on the Plume Rising in Stairwell of Buildings

In recent years, it has been observed that when a fire occurs in a multi-use facility, a toxic fire smoke rapidly rises through the vertical shaft and spreads due to the chimney effect and hot buoyancy. Generally, the fire smoke spreads rapidly through a number of evacuation passages installed for safe evacuation, which adversely affects an emergency situation. Due to the lack of this knowledge among the occupants, the majority of the occupants are evacuated using the stairwells, getting suffocated by poisonous smoke and suffering serious injuries. The present study considered the fire smoke spreading vertically through the stairwell. For this purpose, the power of the heat source and the area of the ventilation windows connected to the stairwell were modified, and the movement and diffusion of the hot plume rising vertically in the stairwell were observed. For the experiment, a 1/20 scaled-down stairwell model was employed, and the temperature ‘T’ and the vertical velocity ‘w’ of the hot plume rising inside the stairwell were measured using a 60 W-180 W heat source power. Numerical analysis was performed using FDS under similar conditions, and the results were compared with the experimental results.

Response of a Small River Plume on Wind Forcing

Wind forcing is the main driver of river plume dynamics. Direction and magnitude of wind determine position, shape, and size of a river plume. The response of river plumes on wind forcing was simulated in many numerical modeling studies; however, in situ measurements of this process are still very scarce. In this study, we report the first direct measurements of frontal movement of a small river plume under variable wind forcing conditions. Using quadcopters, we performed nearly continuous daytime aerial observations of the Bzyb river plume located in the non-tidal Black Sea. The aerial remote sensing was accompanied by synchronous in situ measurements of wind forcing. We assessed spreading patterns of the plume and evaluated movement velocity of its outer border with unprecedentedly high spatial (∼10 m) and temporal (∼1 min) resolution, which was not available in previous studies based on in situ measurements and satellite observations. Based on the collected data, we evaluated the time of response of plume spreading dynamics on changes in wind forcing conditions. The advection velocity of the outer plume border shows linear relation to wind speed with very small response time (10–20 min). The reversal between upstream/downstream plume spreading occurs during several hours under moderate wind forcing conditions. These reversals involve only near-field part of the plume, which cause detachment of the far-field part of the plume. The obtained results are crucial for understanding and simulating spreading dynamics of small river plumes worldwide.

Migration of Co, Cd, Cu, Pb to the groundwater in the area of underground coal gasification experiment in a shallow coal seam in the experimental mine ‘Barbara’ in Poland

A numerical model of inorganic pollutants migration in the area of ​​ underground coal gasification (UCG) reactor in the post-operational phase was constructed in this study. Also the deceleration of migration and the shape of the contaminant plume in individual geological formations of the reactor surroundings, resulting from different values ​​of sorption affinity, were compared. The simulations were carried out for four selected metals (Co, Cd, Cu, Pb), which in relation to the raw coal and post-process char showed different sorption properties. The sorption parameters of the tested systems were determined experimentally on the basis of the Freundlich isotherm equation. The retardation coefficients were calculated and the degree of sorption intensity in hydrogeological media was classified from II (in the cobalt-char and metals-coal systems) to the IV class of sorption intensity (in the copper-char system).The modeling was carried out using the finite element method (FEM) in the COMSOL Multiphysics computing environment in a two-dimensional plane. The simulation of pollutant migration was carried out for the transient state, with the assumed time horizon up to 20 years after the termination of the UCG experiment. The bottom of the cavity formed due to the coal gasification in situ (10 m × 20 m ellipse) was assumed as the source of contamination and the spread of metals in a horizontal plane 200 m long and 200 m wide was analyzed.To compare the extent to which sorption phenomena affect the spread of pollutants, an additional model was constructed, taking into account only the advection–dispersion movement of the contaminant plume. The consequence of sorption interactions for the tested systems was the delay of the contaminant plume migration depending on time since the termination of the gasification process and depending on the distance from the source of pollution. Due to high sorption affinities, the post-process char acts as an effective buffer for inorganic pollutants and slows down the migration of analyzed metals even 20 years after UCG experiment. The greatest slowdown in migration in relation to the velocity of groundwater flow as a result of sorption occurred for copper transport in the char layer.

Effects of radius ratio on annular centrifugal Rayleigh–Bénard convection

We report on a three-dimensional direct numerical simulation study of flow structure and heat transport in the annular centrifugal Rayleigh–Bénard convection (ACRBC) system, with cold inner and hot outer cylinders corotating axially, for the Rayleigh number range $Ra \in [{10^6},{10^8}]$ and radius ratio range $\eta = {R_i}/{R_o} \in [0.3,0.9]$ ( $R_i$ and $R_o$ are the radius of the inner and outer cylinders, respectively). This study focuses on the dependence of flow dynamics, heat transport and asymmetric mean temperature fields on the radius ratio $\eta$ . For the inverse Rossby number $Ro^{-1} = 1$ , as the Coriolis force balances inertial force, the flow is in the inertial regime. The mechanisms of zonal flow revolving in the prograde direction in this regime are attributed to the asymmetric movements of plumes and the different curvatures of the cylinders. The number of roll pairs is smaller than the circular roll hypothesis as the convection rolls are probably elongated by zonal flow. The physical mechanism of zonal flow is verified by the dependence of the drift frequency of the large-scale circulation (LSC) rolls and the space- and time-averaged azimuthal velocity on $\eta$ . The larger $\eta$ is, the weaker the zonal flow becomes. We show that the heat transport efficiency increases with $\eta$ . It is also found that the bulk temperature deviates from the arithmetic mean temperature and the deviation increases as $\eta$ decreases. This effect can be explained by a simple model that accounts for the curvature effects and the radially dependent centrifugal force in ACRBC.

Effect of CO2 Flooding on the Wettability Evolution of Sand-Stone

Wettability is one of the main parameters controlling CO2 injectivity and the movement of CO2 plume during geological CO2 sequestration. Despite significant research efforts, there is still a high uncertainty associated with the wettability of CO2/brine/rock systems and how they evolve with CO2 exposure. This study, therefore, aims to measure the contact angle of sandstone samples with varying clay content before and after laboratory core flooding at different reservoir pressures, of 10 MPa and 15 MPa, and a temperature of 323 K. The samples’ microstructural changes are also assessed to investigate any potential alteration in the samples’ structure due to carbonated water exposure. The results show that the advancing and receding contact angles increased with the increasing pressure for both the Berea and Bandera Gray samples. Moreover, the results indicate that Bandera Gray sandstone has a higher contact angle. The sandstones also turn slightly more hydrophobic after core flooding, indicating that the sandstones become more CO2-wet after CO2 injection. These results suggest that CO2 flooding leads to an increase in the CO2-wettability of sandstone, and thus an increase in vertical CO2 plume migration and solubility trapping, and a reduction in the residual trapping capacity, especially when extrapolated to more prolonged field-scale injection and exposure times.

Numerical Modeling Applied to Leachate Generation using Hydrus – Case Study: Seropédica, Rio de Janeiro, Brazil

ABSTRACT Improper design and management of the cover layer of a sanitary landfill has been proven to produce harmful environmental impacts on the environment. One alternative at hand is to develop scenarios based on simulation of physical and computational models to represent the expected field water balance of a landfill coverage layer. This paper investigates the design of a sanitary landfill final cover in the municipality of Seropédica, which is located at the state of Rio de Janeiro - Brazil. More specifically, the compact soil coverage, which is widely used for landfill final cover of municipal solid waste, is evaluated in contrast to vegetation cover by grass, vegetation cover by brachiaria and capillary barrier. To accomplish such task, hydrometeorological forcing conditions, namely daily rainfall and temperature, were retrieved from the Anchieta weather station, which is situated nearby the study area. The Hydrus 1D and 2/3 D computational codes were employed to develop a set of scenarios to follow the contamination plume evolution within the landfill along the time frame of 20 years with some degree of reliability. It should be noted that the performed evaluation indicates the possibility to control the leachate release and consequently to avoid contaminating the environment, notably to prevent soil and water resources pollution. Vegetation cover by grass and brachiaria showed important control mechanisms with respect to the movement of the contaminant plume. In addition, it should be noticed that the best results for the landfill final cover were achieved for the capillary barrier, while poor performance results were obtained for the commonly employed compact soil.

Quantitative analysis of the influence of capillary pressure on geologic carbon storage forecasts case study: CO2-EOR in the Anadarko basin, Texas

Numerical models are a critical tool for forecasting subsurface multiphase flow associated with geologic carbon storage. The uncertainty of model results stems from many factors, including uncertainty in multiphase flow parameters. Specifically, relative permeability and capillary pressure relationships depend on both the rock properties and fluid properties, and the latter may be highly nonlinear as fluid temperature, and pressure conditions change. Forecasts of trapping mechanisms, phase behavior, and plume movement are impacted by choice of relative permeability and capillary pressure functions and how those functions are calibrated and constrained. In particular, one of the most neglected aspects of such simulations is meaningful capillary pressure processes. A primary goal of this study is to quantify the difference in forecasts for models that utilize capillary pressure functions calibrated with measured data from the results of models without such. Additionally, the relative permeability models developed here were derived from measured capillary pressure data. Those data were used to constrain saturation endpoints in the relative permeability curves and dictate how that relative permeability was distributed spatially. The main conclusions drawn from this analysis include (1) heterogeneity in relative permeability plays a significant role in simulated forecasts of CO2 migration, trapping mechanisms and storage capacity, as well as oil and water production, and (2) capillary pressure, and in particular, the magnitude of capillarity also plays a significant role in these processes. Conversely, if the magnitude of capillarity is small relative to in situ fluid pressures, it imparts insignificant effects on these processes.