Effects of the capillary-entrapped phase on fines migration in porous media

The contamination of soils with heavy metals and its associated hazardous effects are a thrust area of today’s research. Rapid industrialization, emissions from automobiles, agricultural inputs, improper disposal of waste, etc., are the major causes of soil contamination with heavy metals. These contaminants not only contaminate soil but also groundwater, reducing agricultural land and hence food quality. These contaminants enter the food chain and have a severe effect on human health. It is important to remove these contaminants from the soil. Various economic and ecological strategies are required to restore the soils contaminated with heavy metals. Phytoremediation is an emerging technology that is non-invasive, cost-effective, and aesthetically pleasing. Many metal-binding proteins (MBPs) of the plants are significantly involved in the phytoremediation of heavy metals; the MBPs include metallothioneins; phytochelatins; metalloenzymes; metal-activated enzymes; and many metal storage proteins, carrier proteins, and channel proteins. Plants are genetically modified to enhance their phytoremediation capacity. In Arabidopsis, the expression of the mercuric ion-binding protein in Bacillus megaterium improves the metal accumulation capacity. The phytoremediation efficiency of plants is also enhanced when assisted with microorganisms, biochar, and/or chemicals. Removing heavy metals from agricultural land without challenging food security is almost impossible. As a result, crop selections with the ability to sequester heavy metals and provide food security are in high demand. This paper summarizes the role of plant proteins and plant–microbe interaction in remediating soils contaminated with heavy metals. Biotechnological approaches or genetic engineering can also be used to tackle the problem of heavy metal contamination.

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Phytoremediation technologies and their mechanism for removal of heavy metal from contaminated soil: An approach for a sustainable environment


 The presence of residual oil or gas during fines migration in porous media greatly affects particle mobilization and capture. This paper investigates the effects of kaolinite content on fines migration and formation damage in the presence of oil residual. We carried out corefloods on engineered sand-packs that contained different percentages of kaolinite. Each core sample was subjected to brine injections varying from seawater salinity to freshwater. Measurements of the pressure drop and effluent particle size distributions were performed for each injection. It was determined that the main cause of permeability decline was pore throat straining by kaolinite. A higher decline of permeability accompanied by intensive fines production was encountered during freshwater injection. If compared with fines migration under single-phase flow, having a residual phase showed a significant decrease in formation damage and the amount of produced kaolinite. The laboratory data were matched with the analytical model for one-dimensional linear flow. A close agreement between the coreflood data and the model was obtained. The model coefficients were used for well injectivity decline prediction using a numerical one-dimensional radial injection model. The kaolinite content and the residual oil phase greatly impacted the well injectivity decline.

Effects of Kaolinite on Fines Migration and Formation Damage

Over the years, mining and metallurgical activities have rapidly influenced the human population. The manufacturing process of manganese (Mn) compounds and their use in industries increased the negative effect on the environment. Therefore, the recovery process of Mn from metal-containing wastes has become very crucial. Mn is a trace mineral found in various forms in the earth's crust and is present abundantly in terrestrial and aquatic environments. Due to the presence of high-level toxicity in surface waters, aquatic organisms exhibit a high-level toxic response. Mn is composed of many minerals such as oxides, sulfates, carbonates, etc. found naturally in the earth. Chronic exposure to this metal pollutant can result in adverse effects and various symptoms related to neurotoxicity including cognitive, Parkinson's disease, manganism, dystonia, and in plants symptoms like chlorosis in leaves and necrotic leaf spots. Mn is released into water bodies, especially through soil erosion, mining activities, and many anthropogenic activities. The toxicity depends on several aspects including the dose, route of exposure, species, and nutritional status of the individual. This element can be considered a systemic toxicant that can damage the multiple organs of humans. These microorganisms will degrade and detoxify the pollutants in the soil, water, and other environments into a non-toxic form that is not harmful to the environment. This review aims to summarize the toxicity of Mn mining pollutants in the environment as well as in humans, plants, and animals and describes the biological remediation strategies. This review also focuses on the environmental Mn pollution and the future aspects to control the Mn pollutants through biological remediation approaches. 

Ecotoxicological consequences of manganese mining pollutants and their biological remediation


 Injecting CO2 into the saline aquifer is considered to be an effective strategy to mitigate CO2 emissions. Saline aquifers are known to have a wide range of salinities and several evidences showed that different brine salinities give rise to different CO2-brine-rock wetting behaviors as well as different CO2 solubility potential. This will ultimately influence the CO2 plume migration behavior and the overall performance of a CO2 sequestration project. However, associated field-scale CO2 capacity predictions in different saline aquifers received little attention. This study conducts field-scale numerical simulations to analyze the effect of aquifer salinity on the CO2 storage potential. Different CO2-brine flow behaviors undervariablebrine salinities were considered. The results showed that an increase in the plume migration distance was observed in a higher salinity aquifer.While an increase in the brine salinity would result in an increase in residual trapping but a decreased solubility trapping capacities.Also, higher salinity formation observed more mobile CO2 and thus exhibit a worse sealing efﬁciency. We point out that residual trapping capacity evaluation should consider both residual CO2 saturation and the CO2 occupied volume, which both are strong functions of brine salinity.

Effect of Variable Brine Salinities on CO2 Trapping: Implications for CO2 Storage in Saline Acquires

Contaminated soil containing toxic metals and metalloids is found everywhere globally. As a consequence of adsorption and precipitation reactions, metals are comparatively immobile in subsurface systems. Hence remediation techniques in such contaminated sites have targeted the solid phase sources of metals such as sludges, debris, contaminated soils, or wastes. Over the last three decades, the accumulation of these toxic substances inside the soil has increased dramatically, putting the ecosystem and human health at risk. Pollution of heavy metal have posed severe impacts on human, and it affects the environment in different ways, resulting in industrial anger in many countries. Various procedures, including chemical, biological, physical, and integrated approaches, have been adopted to get rid of this type of pollution. Expenditure, timekeeping, planning challenges, and state-of-the-art gadget involvement are some drawbacks that need to be properly handled. Recently in situ metal immobilization, plant restoration, and biological methods have changed the dynamics and are considered the best solution for removing metals from soil. This review paper critically evaluates and analyzes the numerous approaches for preparing heavy metal-free soil by adopting different soil remediation methods. 

Remediation techniques for elimination of heavy metal pollutants from soil: A review.

Impact of Wettability and Injection Rate on Co2 Plume Migration and Trapping Capacity: A Numerical Investigation

Fines migration has not been widely considered during CO2 injection into water-saturated rocks. Mineral dissolution effects are only considered in long-term experiments (weeks to months scale). This study conducts a series of short (few hours) dynamic experiments to study the effect of dissolution and fines migration on CO2 injectivity in cores. Three coreflooding experiments were performed using Berea sandstone at difference salinity brine (0, 10, 30 and 60 g/L NaCl). First, the core plugs were subjected to brine injection. Then, CO2-saturated brine was injected to displace unsaturated brine from the core. Afterward, brine saturated supercritical CO2 (scCO2) was injected into the core. The Pressure drop across the core was monitored and produced water samples were collected continuously during the experiments. To characterize the core sample, X-Ray Powder Diffraction (XRD), X-Ray Fluorescence (XRF), and Scanning Electron Microscopy (SEM) analyses were performed. After the experiment, SEM-EDS analysis was run and registered with the pre-injection images to visualize fines migration. Fines concentration was measured, and ionic chromatography analysis was performed to characterize produced water samples. Numerical simulations were performed to model the experiment geochemical reactions. The permeability of the core sample is significantly reduced after the experiment due to pore blockage. SEM-EDS analysis of the blocked pores and produced fines show blockage is mostly caused by clay, quartz and cement. Numerical simulations showed that the reaction rate; hence, cement dissolution is faster at higher salinity.

Permeability Damage Due to Fines Migration During CO2 Sequestration


 Subsurface reservoir wettability is of vital importance in the prediction of CO2 trapping capacity and containment security. However, quantifying the effect of reservoir wetting behavior on CO2 sequestration potential in heterogeneous reservoirs remains to be challenging. This study conducts field-scale numerical simulations to understand the role of wetting characteristics and injection duration on the migration trend of CO2 plume and trapping capacity. These simulations were conducted on a heterogeneous sandstone reservoir with realistic relative permeability curves. The results indicate that CO2 plume migration and storage efficiency are influenced by wettability and injection duration. A water-wet system leads to higher residual gas trapping with less mobile CO2 and less dissolution. Moreover, an increase in injection duration would result in a decrease in residual trapping but the solubility trapping and plume migration distance would both increase.

Muhammad Arif

Papers

Remediation techniques for elimination of heavy metal pollutants from soil: A review.

Impact of Wettability and Injection Rate on Co2 Plume Migration and Trapping Capacity: A Numerical Investigation

Permeability Damage Due to Fines Migration During CO2 Sequestration

A Numerical Evaluation of the Impact of Wettability on CO2 Trapping Capacity: Implications for Carbon Geo-Sequestration

Influence of Surface Cleaning on the Wettability of Calcite/Oil/Brine Systems