Imbibition Research Articles

Synthesis and surfactant properties of sulfonate Gemini surfactants

Abstract In this study, a novel high salinity resistant, high temperature tolerant sulfonate Gemini surfactant (CK-3) for enhanced oil recovery was synthesized and is described. The critical micelle concentration (CMC) of CK-3 is 7.3 × 10−5 mol L−1 with a surface tension at CMC, γ CMC , of 30.88 mN m−1, and a pC20 value of 4.80. Moreover, increasing temperature led to delayed micellization, indicating the superior surface activity inherent in Gemini surfactants. When CK-3 was evaluated as an imbibing agent, an interfacial tension of 8.3 × 10−2 mN m−1 was observed between a 0.3 wt% CK-3 solution and crude oil, facilitated by hydrophobic group interactions which allow crude oil detachment. Finally, CK-3 molecules exhibited stable adsorption on rock walls, influencing wetting reversal. Zeta potential measurements exceeding 30 mV indicated stability. In aged capillary tubes, a 0.3 wt% CK-3 solution exhibited a rise height of 2.9 cm. Imbibition experiments on natural core samples showed a water imbibition efficiency of 8.73 %, compared to a significantly improved efficiency of 50.78 % with a 0.3 wt% CK-3 solution. This study also demonstrated the imbibition process and mechanisms of the CK-3, providing novel insights for the efficient development of unconventional oil reservoirs and the enhancement of crude oil recovery rates.

Carbon Dots Infused 3D Printed Cephalopod Mimetic Bactericidal and Antioxidant Hydrogel for Uniaxial Mechano-Fluorescent Tactile Sensor.

Cephalopods use stretchy skin and dynamic color-tuning organs for visual communication and camouflage. Inspired by these natural mechanisms, a fluorescent biomaterial for deformation-induced illumination and optical communication is proposed. This is the first report of 3D printed soft biomaterials infused with carbon dots hydrothermally derived from chitosan and benzalkonium chloride. These biomaterials exhibit a comprehensive array of properties, including significant uniaxial stretching, near-instantaneous response to tactile stimuli and pH, UV resistance, antibacterial, antioxidant, noncytotoxicity, and highlighting their potential as mechano-optical materials for biomedical applications. The hydrogel's durability is evaluated by cyclic stretching, folding, rolling, and twisting tests to ensure its integrity and good signal-to-noise ratio. The diffusion mechanism is determined by water imbibition kinetics, network parameters, and time-dependent breathing. Overcoming the common limitations of short lifespans and complex manufacturing processes in existing soft hybrids, this work demonstrates a straightforward method to produce durable, energy-independent, mechano-optical hydrogel. Combined with investigations, molecular dynamic modeling is used to understand the interactions of hydrogel components.

Spontaneous imbibition of unsaturated sandstone under different vertical temperature gradients: neutron radiography experiments and dynamic models

To elucidate the imbibition behavior of water in complex temperature and stress environments, spontaneous imbibition experiments were conducted on unsaturated matrix sandstones at different vertical temperature gradients by neutron radiography technology. Additionally, corresponding dynamic models of water imbibition in porous media were established. The research results reveal the phased characteristics of sandstone spontaneous imbibition and the influence of vertical temperature gradient on the evolution of wetting front. Specifically, the initial development speed of the wetting front increases with an increase in the vertical temperature gradient, indicating a direct relationship. However, the growth rate of the wetting front gradually slows down with increasing time, eventually reaching a saturated state. Model validation demonstrates that the traditional Washburn's law is still valid in isothermal conditions without temperature gradient (G=0). Further analysis indicates that the imbibition rate has a direct correlation with linear thermal expansion coefficient (α) and viscosity temperature coefficient (β) across various vertical temperature gradients, and an inverse correlation with surface tension temperature coefficient (γ). Furthermore, when the values of α, β, and γ fall below 0.001, their impact on the imbibition rate becomes negligible. The sensitivity of the imbibition rate to parameters γ, β, and α decreases in that order, with γ being the most sensitive, followed by β, and α being the least sensitive. Moreover, the relative importance of α, β, and γ dictates their specific influence on the imbibition rate, and a synergistic effect exists among these parameters, which collectively influence the water absorption behavior of sandstone.

Facilitators or predators? The role of seed-feeding beetles in the germination of an ornamental and invasive plant in an urban environment

Leucaena leucocephala is a forage legume that provides cellulose, firewood, and shade in cities, although it presents a dangerous allelopathic and invasive potential. Its main natural enemy is the endophytic beetle Acanthoscelides macrophthalmus (Chrysomelidae: Bruchinae), whose larvae penetrate seeds and can consume the entire endosperm and embryos. However, there is much to explore on how the abundance of larvae inside the seed affects the plant germination, resulting in an antagonistic (predation) or mutualistic (facilitation) interaction. Our goal was to test how these beetles affect the germination of L. leucocephala seeds from an urban environment in Uberlândia, MG. We hypothesized that a single larva inside the seed facilitates germination since the exit holes left break the physical dormancy and enable water imbibition. On the other hand, two or more larvae inside the same seed result in predation, as the amount of endosperm is not enough for beetle satiation before they attack the seed embryo. We collected 100 pods, dissected them, and quantified and qualified the seeds. In the germination experiment, we used healthy seeds (control), scarified healthy seeds (physical treatment), and attacked seeds (one, two, or more larvae). We found that beetles infested 74% of the sampled seeds. Independently of the abundance of larvae inside the seed, attacked seeds did not germinate. The scarified seeds germinate faster and in greater quantity. Therefore, our hypothesis was rejected for the studied plant population. Acanthoscelides macrophthalmus acts only as a predator in an antagonistic interaction that decreases the germination rate of L. leucocephala.

Review on spontaneous imbibition mechanisms in gas-water systems: Impacts on unconventional gas production and CO2 geo-sequestration

Spontaneous imbibition, a fundamental process in porous media, involves the displacement of a non-wetting phase by a wetting phase driven by capillary pressure. It plays a key role in various applications, particularly in unconventional gas production and greenhouse gas geo-sequestration. Despite extensive research in this area, conflicting results and explanations persist regarding imbibition phenomena, particularly in gas-water systems. This paper aims to address this gap by providing a comprehensive review of basic concepts, mechanical analyses, pore-filling patterns, front evolutions, and influencing factors associated with spontaneous imbibition. Mechanical factors including capillary force, viscous force, gravitational force, hydrostatic force, inertial force, capillary back force, and dead end force, play crucial roles in water imbibition with different boundary types. The pore-filling pattern significantly affects microscopic fluid distribution and front evolution during the imbibition process. To resolve conflicting findings, we systematically analyze the influencing factors of spontaneous imbibition within gas-water systems, encompassing rock properties, fluid characteristics, rock-fluid interactions, and reservoir properties. Furthermore, we present an in-depth discussion on the imbibition and trapping mechanisms relevant to unconventional gas production and CO2 geo-sequestration, providing insights into force analyses and influencing factors. Gas production strategies and favorable conditions for CO2 capillary trapping are proposed. Finally, we outline existing knowledge gaps and suggest potential directions for future research. This review thus provides useful insights and suggestions for advancing our understanding of spontaneous imbibition within gas-water systems and optimizing unconventional gas production and CO2 geo-sequestration practices.

Imbibition mechanism of water in illite nanopores of deep shales by molecular simulation

Hydraulic fracturing is an important technique to develop deep shale gas. After hydraulic fracturing, a large amount of fracturing fluid fails to flow back and retains in deep shales. This phenomenon leads to fracturing fluid imbibition and significantly impacts on gas production. However, the understanding of imbibition mechanism in deep shales is very limited. In this work, the microscopic mechanism of fracturing fluid imbibition into illite pores of deep shales was studied using molecular simulation. The factors affecting imbibition were also analyzed. Results show that water imbibition in illite pores can be divided into three stages. In stage 1, the hydrogen bonds between water molecules and illite pore walls are formed, which forces water to enter the pores and becomes a water layer. In stage 2, the hydrogen bonds between water molecules and the water layer are formed, and gas begins to be displaced out of the pores by water. In stage 3, water molecules no longer enter the pores, and the system becomes equilibrium. As for the influencing factors, fugacity pressure mainly affects the imbibition time. The imbibition time becomes longer when fugacity pressure rises. Pore size plays a significant role in imbibition. Gas in illite pores can be totally displaced if the pore size is smaller than 5 nm. The imbibition is also affected by the amount of water. More gas tends to be displaced out of the pores when the ratio of water volume to pore volume (RWP) increases.

Cascading Landslide: Kinematic and Finite Element Method Analysis through Remote Sensing Techniques

Cascading landslides are specific multi-hazard events in which a primary movement triggers successive landslide processes. Areas with dynamic and quickly changing environments are more prone to this type of phenomena. Both the kind and the evolution velocity of a landslide depends on the materials involved. Indeed, rockfalls are generated when rocks fall from a very steep slope, while debris flow and/or mudslides are generated by fine materials like silt and clay after strong water imbibition. These events can amplify the damage caused by the initial trigger and propagate instability along a slope, often resulting in significant environmental and societal impacts. The Morino-Rendinara cascading landslide, situated in the Ernici Mountains along the border of the Abruzzo and Lazio regions (Italy), serves as a notable example of the complexities and devastating consequences associated with such events. In March 2021, a substantial debris flow event obstructed the Liri River, marking the latest step in a series of landslide events. Conventional techniques such as geomorphological observations and geological surveys may not provide exhaustive information to explain the landslide phenomena in progress. For this reason, UAV image acquisition, InSAR interferometry, and pixel offset analysis can be used to improve the knowledge of the mechanism and kinematics of landslide events. In this work, the interferometric data ranged from 3 January 2020 to 24 March 2023, while the pixel offset data covered the period from 2016 to 2022. The choice of such an extensive data window provided comprehensive insight into the investigated events, including the possibility of identifying other unrecorded events and aiding in the development of more effective mitigation strategies. Furthermore, to supplement the analysis, a specific finite element method for slope stability analysis was used to reconstruct the deep geometry of the system, emphasizing the effect of groundwater-level flow on slope stability. All of the findings indicate that major landslide activities were concentrated during the heavy rainfall season, with movements ranging from several centimeters per year. These results were consistent with numerical analyses, which showed that the potential slip surface became significantly more unstable when the water table was elevated.

Deformation dynamics of nanopores upon water imbibition

Capillarity-driven transport in nanoporous solids is widespread in nature and crucial for modern liquid-infused engineering materials. During imbibition, curved menisci driven by high negative Laplace pressures exert an enormous contractile load on the porous matrix. Due to the challenge of simultaneously monitoring imbibition and deformation with high spatial resolution, the resulting coupling of solid elasticity to liquid capillarity has remained largely unexplored. Here, we study water imbibition in mesoporous silica using optical imaging, gravimetry, and high-resolution dilatometry. In contrast to an expected Laplace pressure-induced contraction, we find a square-root-of-time expansion and an additional abrupt length increase when the menisci reach the top surface. The final expansion is absent when we stop the imbibition front inside the porous medium in a dynamic imbibition-evaporation equilibrium, as is typical for transpiration-driven hydraulic transport in plants, especially in trees. These peculiar deformation behaviors are validated by single-nanopore molecular dynamics simulations and described by a continuum model that highlights the importance of expansive surface stresses at the pore walls (Bangham effect) and the buildup or release of contractile Laplace pressures as menisci collectively advance, arrest, or disappear. Our model suggests that these observations apply to any imbibition process in nanopores, regardless of the liquid/solid combination, and that the Laplace contribution upon imbibition is precisely half that of vapor sorption, due to the linear pressure drop associated with viscous flow. Thus, simple deformation measurements can be used to quantify surface stresses and Laplace pressures or transport in a wide variety of natural and artificial porous media.

The Efficiency of Seed Priming with Dead Sea Water for Improving Germination and Early Seedling Growth of Wheat (Triticum aestivum L.) under Salinity

<p>Salinity is considered the most critical environmental factor which negatively affects the germination and growth of plants. In this study, the potential of using Dead Sea water (DS) as a seed priming agent for the mitigation of the adverse effects of salinity on seed germination and growth performance of wheat (<em>Triticum aestivum</em> L.) was investigated. Germination of wheat seeds primed with different doses of DS; 0%, 5%, 10%, 15%, and 20% were evaluated under different saline conditions (0, 100, 200, and 300 mM NaCl). High salinity (300 mM NaCl) remarkably inhibited germination attributes and reduced seedling length. However, seeds primed with DS exhibited improved germination parameters and seedling growth. Among the different DS concentrations used, the 10% DS priming achieved the highest increase in final germination percentage tolerance, germination index, relative germination salt tolerance, and seedling length. The increased tolerance to salinity was associated with improved water imbibition, α-amylase activity, antioxidant capacity and osmotic homeostasis correlated with high proline and soluble sugar levels. In addition, DS priming increased the membrane stability index, and reduced malondialdehyde content and K<sup>+</sup> leakage besides lowering Na<sup>+</sup>/K<sup>+</sup> ratio. Overall, priming with DS could be a promising strategy for minimizing the damaging effects of salinity in wheat.</p>

The Effect of Microstructure on Spontaneous Imbibition of Water in Coals

The Effect of Microstructure on Spontaneous Imbibition of Water in Coals

Quantification of seepage characteristics in shale oil reservoirs: A triple medium model-driven approach

Shale oil is an important unconventional oil and gas resource depicting a complex microstructure with various pore types and fluid distribution. In particular, the fluid flow mechanism and the associated percolation characterization theory have recently gained notable interest. Here we establish a mathematical model to describe non-wetting and wetting phase imbibition in shale oil formation. The model is based on the triple continuum medium theory taking into account the wetting characteristics of the shale/oil/brine system, the percolation processes in inorganic and organic pores, and the dynamic process of adsorption and absorption of crude oil in kerogen. The experimental results of oil and water imbibition were fitted thereby obtaining seepage physical parameters and validating the realiability of the proposed model. The impact of physical properties (e.g. inorganic and organic permeability, equivalent cross-flow coefficient, and diffusion coefficient) on the dynamic characteristics of the imbibition process was also evaluated. The results show that the inorganic permeability is between 10−7–10−4μm2 and the organic permeability is between 10−10–10−6μm2. The imbibition rate demonstrates a positive correlation with inorganic and organic permeability, equivalent cross-flow coefficient, and diffusion coefficient. The larger the difference between inorganic and organic permeability, the more pronounced the “bi-horizontal segment” feature of the shale oil imbibition saturation curve. The proposed model effectively calculates the reserves in both organic and inorganic pores, thereby addressing the time-consuming challenges associated with experimentally obtaining seepage parameters. This study thus provides a theoretical basis for precisely evaluating fluid flow in shale oil reservoirs.

Lattice Boltzmann simulation of counter-current imbibition of oil and water in porous media at the equivalent capillarity

The characterization of oil and water displacement in porous media often relies on the capillary number (Ca = μv/σ cos θ). However, limited investigations have been conducted to explore the relative significance of interfacial tension and wettability in determining oil recovery, particularly under the imbibition mode. To address this research gap, the modified color gradient lattice Boltzmann method has been employed. This study aims to systematically investigate the transient imbibition characteristics, pore-scale events, and morphological features of the two-phase distribution in the matrix, all under the same capillarity but varying capillary numbers. The obtained results indicate that, for a given capillary number, a more water–wet condition generally leads to a higher imbibition recovery. Conversely, the influence of capillary number on oil recovery is complex and contingent upon the capillarity value, i.e., the interfacial tension between oil and water. Additionally, the oil recovery data from all cases have been effectively fitted using the Minkowski functionals, demonstrating a linear correlation. Moreover, an attempt has been made to elucidate the mechanism behind the varying oil recovery observed in different capillarity combinations. This analysis considers factors such as energy conversion, the transient change of the ratio of viscous force over capillarity, and the capillary valve effect. The findings of this study contribute to our understanding of the use of chemical agents to enhance oil recovery and provide valuable insights for determining key two-phase parameters in reservoir simulations.

Genetic variation for tolerance to pre-harvest sprouting in mungbean (Vigna radiata) genotypes.

Pre-harvest sprouting (PHS) is one of the important abiotic stresses in mungbean which significantly reduces yield and quality of the produce. This study was conducted to evaluate the genetic variability for tolerance to pre-harvest sprouting in diverse mungbean genotypes while simultaneously deciphering the association of yield contributing traits with PHS. Eighty-three diverse mungbean genotypes (23 released varieties, 23 advanced breeding lines and 37 exotic germplasm lines) were investigated for tolerance to PHS, water imbibition capacities by pods, pod and seed physical traits. Wide variation in PHS was recorded which ranged between 17.8% to 81% (mean value 54.34%). Germplasm lines exhibited higher tolerance to PHS than the high-yielding released varieties. Correlation analysis revealed PHS to be positively associated with water imbibition capacity by pods (r = 0.21) and germinated pod % (r = 0.78). Pod length (r = -0.13) and seeds per pod (r = -0.13) were negatively influencing PHS. Positive associations between PHS and water imbibition capacity by pods, germinated pod % and 100-seed weight was further confirmed by multivariate analysis. Small-seeded genotypes having 100-seed weight <3 g exhibited higher tolerance to PHS compared to bold-seeded genotypes having 100-seed weight more than 3.5 g. Fresh seed germination among the selected PHS tolerant and susceptible genotypes ranged from 42% (M 204) to 98% (Pusa 1131). A positive association (r = 0.79) was recorded between fresh seed germination and PHS. Genotypes M 1255, M 145, M 422, M 1421 identified as potential genetic donors against PHS could be utilized in mungbean breeding programs.

Improved Amott Method to Determine Oil Recovery Dynamics from Water-Wet Limestone Using GEV Statistics

Counter-current spontaneous imbibition of water is a critical oil recovery mechanism. In the laboratory, the Amott test is a commonly used method to assess the efficacy of brine imbibition into oil-saturated core plugs. The classic Amott-cell experiment estimates ultimate oil recovery, but not the recovery dynamics that hold fundamental information about the imbibition mechanisms. Retention of oil droplets at the outer core surface and initial production delay are the two key artifacts of the classic Amott experiment. This retention, referred to here as the “external-surface oil holdup effect” or simply “oil holdup effect”, often results in stepwise recovery curves that obscure the true dynamics of spontaneous imbibition. To address these holdup drawbacks of the classic Amott method, we modified the Amott cell and experimental procedure. For the first time, using water-wet Indiana limestone cores saturated with brine and mineral oil, we showed that our improvements of the Amott method enabled accurate and reproducible measurements of oil recovery dynamics. Also for the first time, we used the generalized extreme value (GEV) statistics to describe oil production histories from water-wet heterogeneous limestone cores with finite initial water saturations. We demonstrated that our four-parameter GEV model accurately described the recovery dynamics, and that optimal GEV parameter values systematically reflected the key characteristics of the oil–rock system, such as oil viscosity and rock permeability. These findings gave us a more fundamental understanding of spontaneous, counter-current imbibition mechanisms and insights into what constitutes a predictive model of counter-current water imbibition into oil-saturated rocks with finite initial water saturation.

Experimental and numerical simulation study on enhanced oil recovery by N2-Assisted water huff-n-puff in a tight oil reservoir

The water huff-n-puff (WHP) method is widely used for improving oil recovery in tight reservoirs. However, the poor flow conductivity and low sweep efficiency of the matrix restrict the oil recovery performance of this method. Herein, N2-assisted water huff-n-puff (NAWHP) was proposed to improve oil recovery under reservoir conditions. First, the feasibility of NAWHP for tight reservoirs was investigated by comparing the enhanced oil recovery (EOR) performance with that of WHP and N2 huff-n-puff (NHP). The core flooding experimental results revealed that NAWHP facilitated oil recovery improvement, outperforming the existing practice of water or N2 huff-n-puff injection. Thereafter, with the aid of nuclear magnetic resonance (NMR) technology, the application of NAWHP could significantly enhance oil recovery in fractured tight cores, which mainly increased oil recovery from micro- and nanopores in the matrix. Specifically, for submicron pores and micropores, after three cycles of NAWHP, the recovery efficiency increased by 21.35% and 36.19%, respectively, while the recovery only increased by 14.34% and 24.8%, respectively, during WHP. For nanopores and micro/nanopores, the use of WHP increased the total oil recovery by only 4.71%, while the use of NAWHP increased the total oil recovery threefold. Finally, a series of numerical simulations were conducted to explore the effects of different parameters on oil recovery by NAWHP. The results illustrated that a high N2–water ratio (NWR) positively affected the overall oil recovery, but the higher the NWR was, the more difficult to extract the oil below the injection layer. By injecting 13,000 m3 of N2, the maximum swept volume was achieved for the matrix, and water filled the major fractures after injecting 11,000 m3, effectively accomplishing this task. Increasing the soaking time positively influenced oil recovery, N2 diffusion within the matrix led to an even distribution over 50 days, and water imbibition caused a significant increase in the oil saturation in hydraulic fractures within 30 days. The application of NAWHP increased the number of huff-n-puff cycles of water from a maximum of 3–5.

Imbibition of water into a cellulose foam: The kinetics

Cellulose foams are representative of many porous engineering solids that can absorb a large quantity of fluid such as water. Experiments are reported to give insight into water rise in cellulose foams and the underlying mechanisms. The water rise characteristic of water height h versus time t displays a distinct knee on a log-log plot; this knee separates an initial regime where h scales as t1/2 from a subsequent regime where h scales as t1/4. The rate of water rise below the knee is consistent with the Washburn law of water rise in a single dominant capillary, and the knee in the h(t) curve suggests that the Jurin height of this large capillary has been attained. Water rise in the foam above the knee of the h(t) curve is interpreted as water rise in a population of small capillaries with a wide range of radius that feed off the dominant capillary. A series of critical experiments support this interpretation, including water rise in inclined columns, and water rise from a limited reservoir of water. A simple analytical model is used to provide a physical explanation for the observations. Additionally, X-ray computer tomography is used to deduce the probability density function of the small capillaries. The experimental findings are in support of the hypothesis that water rise in the cellulose foam is driven by capillary action and not by diffusion.

Role of cell wall polysaccharides in water distribution during seed imbibition of Hymenaea courbaril L.

Seed water imbibition is critical to seedling establishment in tropical forests. The seeds of the neotropical tree Hymenaea courbaril have no oil reserves and have been used as a model to study storage cell wall polysaccharide (xyloglucan - XyG) mobilization. We studied pathways of water imbibition in Hymenaea seeds. To understand seed features, we performed carbohydrate analysis and scanning electron microscopy. We found that the seed coat comprises a palisade of lignified cells, below which are several cell layers with cell walls rich in pectin. The cotyledons are composed mainly of storage XyG. From a single point of scarification on the seed surface, we followed water imbibition pathways in the entire seed using fluorescent dye and NMRi spectroscopy. We constructed composites of cellulose with Hymenaea pectin or XyG. In vitro experiments demonstrated cell wall polymer capacity to imbibe water, with XyG imbibition much slower than the pectin-rich layer of the seed coat. We found that water rapidly crosses the lignified layer and reaches the pectin-rich palisade layer so that water rapidly surrounds the whole seed. Water travels very slowly in cotyledons (most of the seed mass) because it is imbibed in the XyG-rich storage walls. However, there are channels among the cotyledon cells through which water travels rapidly, so the primary cell walls containing pectins will retain water around each storage cell. The different seed tissue dynamic interactions between water and wall polysaccharides (pectins and XyG) are essential to determining water distribution and preparing the seed for germination.

Model PEM water electrolyzer cell for studies of periodically alternating drainage/imbibition cycles

Investigating the counter-current two-phase flow within the anodic porous transport layer (PTL) of polymer electrolyte membrane water electrolyzers (PEMWEs) is a complex yet intriguing challenge. Until now, the gas-liquid invasion processes inside PTLs are only to a limited extent accessible under operation conditions, usually using sophisticated and expensive optical approaches, i.e., neutron imaging. We propose a model-supported experimental method with a fully operating microfluidic PEMWE, that allows to examine pore-scale oxygen-water distributions at the anode with high spatial and temporal resolution. The microfluidic cell is made of transparent Poly-Methyl-Methacrylate (PMMA), and the PTL is simplified by a quasi-2D pore network (PN) with a uniform pore-throat structure in the first preliminary study. The proposed setup is a significant advancement over previous studies, where gas was only injected at a constant flow rate from a single point. Test cases with current densities of 0.1, 1, and 2 A/cm2 and water flow rates of 1, 3, 5, and 10 ml/min were realized in the novel setup. We found periodically alternating invasion of oxygen (drainage) and water (imbibition), which were analyzed based on image sequences as well as voltage measurements. The experimental data is additionally supported by pore-scale Lattice Boltzmann (LB) and PN simulations. The preliminary results with the simplified PN structure are used to study the dominating transport mechanisms, revealing that drainage and imbibition occur simultaneously and are affected by evaporation and wetting liquid films formed in sharp pore corners. These phenomena are also expected to occur in more complex PTL structures. The preliminary results can, therefore, be regarded as an important basis for PTL studies, which are structurally more complex.

Modification of a hybrid fluoro-surfactant containing double fluorocarbon chains on the carbonate and shale rocks for the wettability reduction of water and oil

An original hybrid fluoro-surfactant DHE with double fluorocarbon chains was synthesized. This surfactant aimed to reduce significantly the wettability of water and oil on the carbonate and shale rocks and adapt to the high salinities of the formation water. This could enhance the imbibition and injection of water in the matrix of carbonate reservoirs and the fracturing flowback in shale reservoirs. DHE showed good interface activities in salt-free and brine solutions, and remarkable water- and oil-wettability reduction on the two kinds of rocks. Moreover, its tolerant-NaCl concentrations were not below 80 g/L. The diameters of DHE mono-molecules were 1.5–4 nm and innumerable worm-like micelles were observed by TEM at the critical micelle concentration of 1.2 g/L in water. After being modified only using the 0.03 g/L DHE saline with 30 g/L NaCl for the carbonate rock, the surface energy was reduced substantially, so the primary water- and oil-wetting (θ: 43–50.6°) on the rock changed to nearly intermediate wetting (θ: 85.0−87.4°), which was the most ideal wetting state for oil and gas production in reservoirs. Moreover, the modifying effect of DHE on the rocks became stronger with the DHE and salt concentrations in the DHE brines. Therefore, it was found that the capillary pressure could be changed to zero using very small amounts of hybrid fluoro-surfactants such as DHE because the rocks could be altered to intermediate wetting for water and oil phases. Consequently, the oil recovery in the water-flooding of carbonate reservoirs and the fracturing flowback in shale reservoirs would be improved significantly.

Nanotechnology Applications in Enhanced Oil Recovery (EOR)

Enhanced Oil Recovery (EOR) techniques are crucial for maximizing crude oil extraction from reservoirs, especially when traditional methods leave significant amounts of oil untapped. Recent advancements in nanotechnology have introduced innovative solutions to longstanding challenges in the oil industry. This research paper explores the application of nanotechnology in EOR, emphasizing the unique properties of nanoparticles that make them highly effective in this context. Nanoparticles, defined by their nanometer-scale dimensions, exhibit high surface area to volume ratios, quantum effects, and enhanced reactivity. These properties enable various mechanisms in EOR, including improved wettability, reduction in interfacial tension, enhanced thermal stability, selective plugging and fluid diversion, and catalytic effects. The study details how silica and titanium dioxide nanoparticles can modify rock surface properties, leading to better water imbibition and oil displacement. It also discusses how surfactant-coated nanoparticles can reduce the interfacial tension between oil and water, facilitating easier oil flow. Furthermore, the research highlights the role of metal oxide nanoparticles, such as aluminum oxide and zinc oxide, in enhancing thermal conductivity and stability during thermal EOR methods like steam flooding. The ability of polymer-coated nanoparticles to selectively plug high-permeability zones and redirect injection fluids is examined, demonstrating how this can lead to a more uniform sweep and higher oil recovery. The catalytic properties of certain nanoparticles, such as iron oxide, are also explored for their potential to promote in-situ chemical reactions that generate gases aiding oil displacement. Field applications and case studies underscore the practical benefits of nanotechnology in EOR. Examples include the use of silica nanoparticles in Middle Eastern oil fields, polymer-coated nanoparticles in Canadian heavy oil reservoirs, and iron oxide nanoparticles in Indian oil fields. These case studies have shown significant increases in oil recovery rates and operational efficiencies. However, the research also identifies several challenges that must be addressed for the widespread adoption of nanotechnology in EOR. These include the high costs and scalability issues associated with nanoparticle production and deployment, potential environmental and health risks, and the need for customized solutions to cater to the unique conditions of different reservoirs. In conclusion, while nanotechnology presents promising advancements in EOR through various mechanisms, overcoming challenges related to cost, scalability, and environmental impact is crucial. As research progresses, nanotechnology is poised to play a vital role in enhancing oil recovery and meeting global energy demands.