Wettability Index Research Articles

Spent tea leaves and tea bags - Promising biofuels?

The spent tea leaves used after the extraction of liquid from processed tea are insufficiently utilized waste, rich in essential amino acids, polyphenols, alkaloids, and minerals, produced in large quantities, e.g., in tea houses, hospitals, school canteens, etc. Therefore, this study is aimed at characterizing this waste, how it is processed into pellets and how it subsequently increases its energy potential by torrefaction. The influence of the method of tea packaging, i.e., loose tea leaves or tea bags, was also considered. Several types of tea waste were processed using a pilot plant pelletizing press and torrefaction stand. The prepared pellets were characterized by mechanical parameters, such as the pellet durability index, the wettability index, water resistance, hardness, or specific bulk density, and were integrated by FTIR measurements. Furthermore, pellet's energy parameters, such as higher heating value, lower heating value, and elemental analysis, were compared. The results show that non-torrefied pellets have an average combustion heat of 19 kJ kg−1, while torrefied pellets have a value of 9 kJ kg−1 higher. Overall, the study demonstrates that spent tea leaves can be converted into a sustainable source of bioenergy and presents a solution for the treatment of this waste, as well as a renewable energy option.

A protectant for Lactobacillus rhamnosus based on whey protein isolate and isomalt: Stress resistance and underlying mechanisms

Probiotics are exposed to a variety of abiotic and biotic stresses during food fermentation and production, such as acidity, heat, osmolality, and oxidation, which affect their metabolic activity and efficiency. Therefore, it is essential to develop new protective agents to maintain the activity and stability of probiotics. This study introduces a new protectant, spray-dried whey protein isolate (WPI) and isomaltose (ISO). We evaluated the effects of four WPI-ISO ratios (1:0, 2:1, 1:1, 1:2) on the physical properties, including moisture content, water activity (aw), wettability, and glass transition temperature. In addition, we evaluated the environmental tolerance of Lactobacillus rhamnosus to different WPI-ISO ratios under thermal, storage, and simulated gastrointestinal conditions. The results showed that the moisture content (< 7 %) and water activity (< 0.3) of the protectant and probiotic powders met storage stability requirements. The moisture content, water activity, wettability index (WI), and glass transition temperature decreased significantly with the addition of isomalt, thereby improving the pressure resistance of L. rhamnosus through the synergistic effect of WPI and ISO. The WPI-ISO protectant not only improved the environmental tolerance and wettability of probiotics by reducing the moisture content and water activity but also significantly improved the survival rate of L. rhamnosus under various stress conditions such as high temperature and gastrointestinal environment. L. rhamnosus maintains good activity with a viable bacterial count of over 9 lg CFU/g after 90 days of storage, demonstrating effective protection against the environment stress. This study provides a promising new strategy to improve the stability of probiotics in the food industry.

Sand blasting for hydrophobic surface generation in polymers: Experimental and machine learning approaches

Wettability is a crucial surface feature of polymers due to their numerous interaction-destined applications. This study focuses on the application of sand blasting process for investigating the wettability of polymeric materials to produce hydrophobic behavior. Four different polymeric materials, Acrylonitrile Butadiene Styrene (ABS), Poly(methyl methacrylate) (PMMA), Polypropylene (PP), and Polycarbonate (PC) underwent sand blasting with varying process parameters, following a comprehensive plan for the design of experiments. Subsequent analyses included surface roughness measurement and wettability tests, supplemented by scanning electron and confocal microscopy observations to gain deeper insights into the blasted surfaces. A predictive model based on a machine learning algorithm was developed using the backpropagation technique to correlate the surface treatment parameters to surface roughness and wettability indexes. From the experimental results sand blasting proved to be efficient in creating hydrophobic surfaces on all the tested materials. The developed neural network demonstrated high fitting degrees between the predicted and measured values. ABS exhibited the most hydrophobic behavior and emerged as a strong candidate for further investigations.

Comparative Laboratory Wettability Study of Sandstone, Tuff, and Shale Using 12-MHz NMR T1-T2 Fluid Typing: Insight of Shale

Summary Wettability is a fundamental parameter significantly influencing fluid distributions, saturations, and relative permeability in porous media. Despite the availability of several wettability measurement techniques, obtaining consistent wettability index results, particularly in tight reservoirs, remains a challenge. Nevertheless, obtaining accurate wettability indices is crucial for gaining a more profound understanding of rock properties and precisely identifying and evaluating oil recovery processes. This study adapts T1-T2 nuclear magnetic resonance (NMR) in twin plugs (cores cut in half from the middle) style wettability measurement for different reservoirs. The fluid typing in different lithologies by T1-T2 NMR is proved to be effective by introducing D2O with a modified pressurization saturation process. Therefore, demarcating the regions requires multiple experiments, including sole brine, sole oil phase, and D2O imbibition processes, to define oil and water distribution regions. Such fluid typing ability enables better accuracy in wettability characterization. The weighing method shows good agreement with the T2 spectrum but lacks the ability to differentiate fluids. It is observed that the same fluid in various porous media displays different divisions of T1/T2 ratios. The wettability index of sandstone, tuff, and shale measured by weighing and T1-T2 NMR method are compared and studied to demonstrate the applicability of different methods. The weighing method and the NMR method, as modified-Amott methods, share the same fundamental principle but differ in their measurement techniques. This study’s T1-T2 NMR wettability indices are −0.52, 0.06, and 0.14, whereas the weighing wettability indices are −0.63, 0.07, and 0.34 of sandstone, tuff, and shale, respectively. In addition to the difference in shale wettability index, there are also differences in shale porosity measured by methods with/without the ability to differentiate the fluid types. The T1-T2 NMR method is more accurate in measuring the wettability of shale because it can distinguish among free water in pores, structural water, and clay-bound water in smectitic clay minerals. If the clay-related water is not treated properly, the hydrophilicity of the shale will be overestimated. Ultimately, four types of pores (water-wet, oil-wet, mixed-wet, and unconnected pores) are classified and quantified by the proposed NMR method.

Effects of nano-smart water on enhanced oil recovery in carbonate reservoirs: Interfacial tension reduction and wettability alteration

Several studies have revealed that nanofluid and smart water flooding are cost-effective methods, considering the effect of nanoparticles and potential determining ions (PDIs) for enhanced oil recovery in carbonated reservoirs. This study presents the performance of nano-smart water synthesized with surface-modified SiO2 nanoparticles dispersed in PDI-controlled seawater (SW), ensuring dispersion stability in high-temperature and high-salinity reservoirs. The interfacial tension (IFT) and contact angle of the oil/nano-smart water/carbonate rock system were measured using kerosene as an oil phase. At this time, nanoparticle concentrations ranged from 0.5 to 3 wt% and PDI concentrations ranged from 1,000 to 5,000 ppm, such as KCl, MgCl2, MgSO4, and K2SO4. In addition, the IFT and contact angle of SW, low salinity water (LSW), and nanofluid were measured for comparison. It was observed that at nanoparticle concentrations higher than 1 wt%, the IFT values of nano-smart water remained constant or decreased slightly to below 31.91 mN/m compared with nanofluids at 32.18 mN/m, regardless of PDI type and concentration. This indicates that using nano-smart water instead of LSW and SW is expected to reduce the IFT in the oil/water system. The contact angle measurements revealed that the wettability index is 2.57–5.07 times higher in nano-smart water than in nanofluids. This implies that wettability alteration is accelerated by the synergistic effect of PDIs and nanoparticles. Specifically, PDI control with MgSO4 or K2SO4 is highly effective in changing the contact angle of carbonate from strongly oil-wet to strongly water-wet due to the ion exchange reaction of SO42- in oil/water/carbonate rock system. The nano-smart water used in this study is expected to be utilized as an injection fluid under harsh conditions for enhanced oil recovery.

Study of Biocomposite Films Based on Cassava Starch and Microcrystalline Cellulose Derived from Cassava Pulp for Potential Medical Packaging Applications

This study aimed to develop biocomposite films based on cassava starch and microcrystalline cellulose (MCC) derived from cassava pulp for potential medical packaging applications. MCC was extracted from cassava pulp, and its structure and chemical composition, crystallinity, and thermal properties were characterized. The MCC showed a yield of 14.92% and crystallinity of 46.91%. Different MCC contents (1%, 3%, and 5% w/w of starch) were incorporated into cassava starch films. The effects of MCC contents on film properties, including morphology, thickness, mechanical strength, chemical interactions, moisture content, surface wettability, and water activity index, were studied. The effects of UV-C sterilization on the disinfection of starch/MCC on film properties were determined. Results showed that all starch/MCC films exhibited good transparency and thickness ranging from 127 to 144 µm. As MCC content increased from 1 to 5%, Young’s modulus and tensile strength of the films improved significantly from 112.12 to 488.89 MPa and 3.21 to 11.18 MPa, respectively, while elongation at break decreased from 44.74 to 4.15%. Incorporating MCC also reduced film surface wettability, with the water contact angle increasing from 69.17° to 102.82°. The starch/3%MCC holds promise as a biocomposite film for medical packaging applications, offering advantages in terms of good transparency, mechanical properties, and surface hydrophobicity. Furthermore, the absence of microbial growth in the sterilized gauze pad with sealing in the sterilized starch/3%MCC film confirms that the UV-C sterilization, 30 min for each side at 254 nm effectively eliminated any microorganisms present on the starch/3%MCC film without damaging the film properties. This finding highlights a reliable approach to ensuring the sterility of starch/MCC films for medical packaging applications.

Nuclear magnetic resonance experiments on the time-varying law of oil viscosity and wettability in high-multiple waterflooding sandstone cores

A simulated oil viscosity prediction model is established according to the relationship between simulated oil viscosity and geometric mean value of T2 spectrum, and the time-varying law of simulated oil viscosity in porous media is quantitatively characterized by nuclear magnetic resonance (NMR) experiments of high multiple waterflooding. A new NMR wettability index formula is derived based on NMR relaxation theory to quantitatively characterize the time-varying law of rock wettability during waterflooding combined with high-multiple waterflooding experiment in sandstone cores. The remaining oil viscosity in the core is positively correlated with the displacing water multiple. The remaining oil viscosity increases rapidly when the displacing water multiple is low, and increases slowly when the displacing water multiple is high. The variation of remaining oil viscosity is related to the reservoir heterogeneity. The stronger the reservoir homogeneity, the higher the content of heavy components in the remaining oil and the higher the viscosity. The reservoir wettability changes after water injection: the oil-wet reservoir changes into water-wet reservoir, while the water-wet reservoir becomes more hydrophilic; the degree of change enhances with the increase of displacing water multiple. There is a high correlation between the time-varying oil viscosity and the time-varying wettability, and the change of oil viscosity cannot be ignored. The NMR wettability index calculated by considering the change of oil viscosity is more consistent with the tested Amott (spontaneous imbibition) wettability index, which agrees more with the time-varying law of reservoir wettability.

Synergy of Al2O3/GO hybrid nanofluids: Molecular dynamics perspective on dispersion/adsorption evolution and its tribological validation

A synergistic Al2O3/GO hybrid nanofluid was developed, aiming to attain prominent tribological properties for application in mechanical engineering. On the support of a molecular dynamics approach, amorphous models were simulated, thus illustrating the agglomeration or the adsorption in nanofluids, as well as revealing the evolution of the laminated adsorbed structure. Further, single-component or hybrid nanofluids were characterized and their tribological validations were performed. The results showed that the modified nanofluids realized dispersion equilibrium and suspension stabilization at the molecular level, and their wettability or thermo-physical indexes were improved, which was beneficial for the tribological performance. Especially in hybrid nanofluids, the synergistic effect further enhanced these capabilities, thereby maintaining a small friction coefficient and a flat wear region.

EXPLORING THE WETTABILITY CHARACTERISTICS OF ARGILLACEOUS SILTSTONE WITH IMBIBITION AND NMR TECHNIQUE FOR MARINE RESERVOIR EXPLOITATION

The argillaceous siltstone reservoirs in South China Sea involves a wide variety of fossil resources, such as gas hydrate, marine oil, natural gas, and other mineral resources. The argillaceous siltstone with mixed wettability characteristics is easily dispersed in water, and it is difficult to study the wettability of argillaceous siltstone based on water imbibition technique. In this work, an innovative method is proposed to demonstrate the mixed wettability based on imbibition and nuclear magnetic resonance (NMR) technique. The contact angle results show that the affinity of argillaceous siltstone for oil is stronger than that for water. However, the imbibition volume of water is much larger than that of oil. The oil imbibition curve is linear, while water imbibition curve has a two-stage feature. This difference can be explained by the expansion of clay, where more water wet surfaces are exposed to the liquid, leading to changes in wettability. In addition, the coexistence of organic matter and inorganic clay minerals results in a mixed wetting characteristic. Based on NMR technology, a micro wettability index is proposed to quantitatively characterize the micro wettability heterogeneity. The micro water (or oil) wettability index of micropores (0.01-10 ms) is approximately equal to 0.5, indicating the mixed wettability. The micro water wettability index of mesopores (10-500 ms) is approximately equal to 1.0, indicating strong water wettability. These pores or cracks may be induced by clay minerals expansion. The micro oil wettability index of macropores (&amp;#62; 500 ms) is approximately equal to 1.0, indicating strong oil wettability, which is resulted from significant accumulation of organic debris enrichment. It is of great significance to improve the exploration and exploitation efficiency of mineral resources in the South China Sea.

Research on the Adsorption Law of HFAD Agents on the Surface of Porous Media during Hydraulic Fracturing-Assisted Oil Displacement in Low-Permeability Reservoirs.

Adsorption loss of surfactants in porous media is one of the key factors affecting their application in low-permeability reservoirs. The hydraulic fracturing-assisted oil displacement (HFAD) technology can effectively reduce the adsorption loss of surfactants in porous media. However, the adsorption laws of HFAD agents (surfactants) during the HFAD process are still unclear. It was studied based on physical simulation experiments in this paper. The results showed that 0.3% SY-D as the HAFD agent achieved the best effect, which could reduce the oil-water interfacial tension to 0.0239 mN/m and increase the wettability index to 0.7492. In the high-pressure injection process of HFAD technology, the injection pressure and core permeability are positively correlated with the dynamic saturation adsorption capacity of the HFAD agent on the surface of porous media and the ambient temperature is negatively correlated with it. The higher the injection pressure and the larger the core permeability, the lower the dynamic saturation adsorption capacity of the HFAD agent on the porous media surface. In addition, since adsorption is an exothermic process, increasing the temperature has an inhibitory effect on adsorption. The higher the temperature, the slower the adsorption process of the HFAD agent on porous media. Among the three influencing factors, permeability has the greatest influence on the dynamic saturation adsorption capacity of the HFAD agent on the surface of core porous media, followed by injection pressure, and temperature has the least influence on it. Therefore, when implementing HFAD technology for the reservoir with low permeability, it can be considered to increase the injection pressure of HFAD technology to reduce the dynamic saturation adsorption capacity so as to increase the effective concentration of the agent. The research results have certain guiding significance for the application of HFAD technology in the field.

The Effect of Long-Term Farmyard Manure and Mineral Fertilizer Application on the Increase in Soil Organic Matter Quality of Cambisols

Soil organic matter (SOM) quantity and quality are important factors that significantly influence soil fertility. SOM quality indicators change throughout time. In this study, long—term field experiments (22–50 years in duration) on a Cambisol at four sites in the Czech Republic were selected. Seven crops were successively rotated in the sequence: clover, winter wheat, early potato, winter wheat, spring barley, potato, and spring barley with interseeded clover. Five treatments were investigated, including an unfertilized treatment, farmyard manure, and various combinations of farmyard manure and mineral fertilization. A total of 40 t ha−1 of farmyard manure was applied to the early potato and potato crops. Combining organic and mineral fertilizers increased soil organic matter quality and quantity over unfertilized or organic only treatment. The highest intensity of mineral fertilizers in our trials elevated the mean of carbon sequestration efficiency to 45.6% in comparison to pure manure treatment which reached only 22.9% efficiency. A strong correlation was established between the total glomalin content and soil organic matter carbon, fulvic acid, humic acid, carbon hot water extraction, potential wettability index (PWI), and aromaticity index. The PWI was also strongly correlated with these indicators. The E4/E6 ratio indicator was shown to be a much less sensitive method for reflecting the change in soil organic matter quality.

Long-Term Application of Manure and Different Mineral Fertilization in Relation to the Soil Organic Matter Quality of Luvisols

Long-term field experiments were conducted on luvisol at five sites in the Czech Republic (42–48-year duration). The average total organic carbon content in the soil varied between 9.0 and 14.0 g kg−1. In these trials, seven crops were rotated in the following order: clover, winter wheat, early potato, winter wheat, spring barley, potato, and spring barley with interseeded clover. Five treatments were studied: unfertilized treatment (Con), farmyard manure (F), and combinations of farmyard manure with three mineral fertilization levels (F+M1, F+M2, F+M3). Plant residues were not incorporated into the soil. An amount of 40 t ha−1 of farmyard manure fresh matter was applied twice during crop rotation. Intensive mineral fertilizer (F+M3) increased the average value of the carbon sequestration efficiency (CSE) by 12.9% and up to 26.3%. Combining organic and mineral fertilizers at moderate and higher intensities increased the soil organic matter quantity and quality compared to the unfertilized or manure treatment. Data on the glomalin content can be used to study the organic matter quality. We determined a strong correlation between the total glomalin content and the soil organic matter carbon, fulvic acid content, humic acid content, extractable carbon content, and dissolved organic carbon content, as well as the potential wettability index and aromaticity index.

Nanoemulsions of essential oils stabilized with saponins exhibiting antibacterial and antioxidative properties

Abstract Functional foods, drug delivery systems, and cosmetics are the main areas of application for multiphase systems, where the use of naturally derived compounds is preferred. Hence, this study aimed to assess the possibility of using natural surfactants and saponin-rich extracts to produce emulsions containing antibacterial and antioxidant cinnamon and clove essential oils (EOs). The analyses of nanoparticles using dynamic light scattering showed that the addition of plant extracts to solutions allows one to obtain stable emulsions and decreased zeta potential (&lt; −40 mV) and droplet size (&lt;200 nm). In all investigated emulsions, the increase of antioxidative properties was observed when both EOs and plant extracts were used. The emulsion with clove oil stabilized with Quillaja saponaria bark saponins has the highest combined antioxidative properties (3.55 ± 0.01 μg gallic acid equivalent per g). Additionally, a stronger antibacterial action against Pseudomonas bacteria was observed for clove oil with Quillaja saponaria and cinnamon oil with Glycyrrhiza glabra. In addition, plant extracts did not affect significantly the other properties of the oil emulsions, e.g. wettability, colour, and refractive index. All results show that the proposed emulsions can be helpful in the preparation of multifunctional emulsions, where the co-action of saponins and EOs is especially beneficial.

Influence of Rock Firing on the Wettability of Clay-Rich Sandstones

Rock firing is a conventional technique of core preparation to prevent clay swelling and fines migration in clay-rich rock; however, the influence of rock firing on the wetting behaviors and alterations of mineralogical compositions of clay-rich sandstones is not yet explicit. Thus, we assessed and compared the impacts of rock burning at two different temperatures (700 and 1100 °C) on the changes in wetting states of Bentheimer (BN) and clay-rich Bandera Gray (BG) sandstones through contact angle measurement, Amott wettability index determination, and thermogravimetric analysis (TGA). Results showed that rock firing makes the rocks more water-wet, but the clay-rich BG sandstone becomes significantly more water-wet than the quartz-dominated BN rock with increasing temperature. There was no change in rock porosity due to firing, but some clay remained, whereas some clays were transformed into other minerals after rock firing. Particularly, there were thermal transformations of clay to quartz and the disappearance of dolomite, chlorite, and clinochlore. Such transformation of these minerals into alkali metal oxide silicates dispersed on the rock matrix makes the surface more polar and enhances the interactions with water molecules, resulting in more water wettability for the BG sandstone. The study suggests that rock firing could change the clay-rich rock-wetting state into a more water-wet condition than the clay-poor or zero-clay sandstone samples; thus, the influence of rock burning on rock-wetting behavior should be considered to ensure an accurate prediction of the rock-wetting state due to rock burning. Moreover, burning at 1100 °C is recommended to achieve effective clay transformation and removal in clay-rich rock to prevent swelling, fines migration, and clay–fluid interactions.

CONSTRUCTION OF MULTILEVEL STATISTICAL MODELS FOR PREDICTING WETTABILITY INDICATORS OF EASTERN LAMBEISHOR AND YAREYU FIELDS

Link for citation: Saetgaraev A.D., Galkin V.I., Putilov I.S., Nevolin A.I. Сonstruction of multilevel statistical models for predicting wettability indicators of Eastern Lambeishor and Yareyu fields. Bulletin of the Tomsk Polytechnic University. Geo Аssets Engineering, 2023, vol. 334, no. 5, рр.63-69. In Rus. The relevance. All domestic standards for laboratory studies of core oil and gas reservoirs prescribe to clean it from hydrocarbons by extraction. Cleaning of core samples is included in the stage of preparation for the main types of research. For this, a wide range of different solvents and special extraction and distillation apparatuses are used. Core samples placed in the apparatus undergo multiple cleaning cycles for a long time with high -temperature exposure. This approach to the preparation of core samples is traditional and is used for both standard and special studies. However, extraction leads to a distorted understanding of the natural wettability of the rock surface, which is subject to change and, as a rule, hydrophilizes. In this regard, it is of scientific and practical interest to assess rock wettability at various stages of sample preparation – before and after the extraction. The main aim: development of a methodology for predicting the wettability of core samples before extraction from hydrocarbons using statistical research methods. Objects: core samples of the Zadonskaya deposit (D3zd) of the Eastern Lambeishor field, Artinskaya (P1ar) and Assel-Sakmarskaya (P1a+s) deposits of the Yareyu field. Methods: Amott (Amott–Harvey) method, statistical methods. Results. With the help of a set of laboratory studies using various statistical methods, a methodology was developed for predicting the values of the wettability index for oil before extraction based on the porosity and permeability properties of core samples.

Influence of rock permeability and surface conditioning on carbonate wettability: A link between contact angle and Amott-index

The wettability of crude oil/brine/rock system is of great importance in determining oil recovery during water displacement processes. The wetting behavior of rocks has traditionally been assessed via a range of experimental techniques such as the Amott tests and contact angle measurements. While the Amott wettability is known to be influenced by a range of factors, still the impact of rock permeability, rocks surface/saturation condition and initial water saturation remains unclear. Furthermore, a link between Amott wettability and contact angle is missing which is vital to characterize macroscopic vs. core scale wettability. Therefore, in this study, we investigated the effect of permeability, rocks surface/saturation condition and initial water saturation on Amott tests and contact angle measurements using Indiana limestone. We further attempt to experimentally explore the relationship between the contact angle and Amott-Harvey wettability index (IAH) for different rocks. We demonstrated that, in addition to surface texture (roughness) and surface chemistry (heterogeneity), rock surface wetting behavior depends also on the rock permeability and surface/saturation condition (Dry,Sw=1,Sor,SwirrandSo=1). Moreover, a comparison of the observed values for the Amott and contact angles, showed that only when the rock has moderate to high permeability (up to 15.17 mD) will the Amott index corresponds to the wetting state estimated using contact angle method. The influence of several factors on wettability via IAH and contact angle is evident. While permeability demonstrated a positive correlation with wettability, Sor exhibited a negative correlation. For water-wet rocks, contact angle showed weak positive correlation with IAH, while negative correlations were observed in the case of intermediate- and oil-wet rocks. In addition, exceptions were found in the correlations; unlike the IAH, contact angle is weakly correlated with both Sor and Swi obtained from the imbibition experiments. Lastly, spontaneous imbibition time becomes slower and tends to underestimate IAH as rock permeability decreases. The findings from this study will thus broaden the understanding of the interplay of different petrophysical parameters and the relationship between different wetting indices.

Microscale Reservoir Wettability Evaluation Based on Oil–Rock Nanomechanics

Low oil production and rapid production decline epitomize the challenges of unconventional reservoir development. Rocks in the formation with micro-/nanoscale pore-throat units possess an immense surface area. Consequently, the wettability of rocks plays a crucial role in the relative permeability of oil/water, the injection pressure, the distribution and morphology of residual oil, and hence the ultimate oil recovery. Contact angle, as a frequently used method to evaluate wettability, is susceptible to oil-water saturation, imbibition, and surface roughness of rock slices. In addition, the measurement scale (droplet of several millimeters) does not match the flow scale (pore units in micro- or nanoscale). Therefore, this paper established a new wettability evaluation method based on oil–rock interaction. Molecular dynamics simulation results demonstrated that the interaction energy between the oil molecule and walls with different wettabilities shows a distinct discrepancy. Accordingly, nanomechanics by AFM was utilized to measure the oil molecule–pore wall interaction force. It was found that the interaction force increases with the augmented hydrophobicity of the pore wall due to hydrophobic force. In addition, the reservoir rock wettability index was defined using the oil–rock interaction force in the nanoscale. The wettability index has an excellent linear correlation with the intrinsic contact angle. The wettability evaluation method based on the oil–rock interaction force is more direct, facile, and rapid and overcomes the limitation of the traditional contact angle method.

A potential NMR-based wettability index using free induction decay for rocks

The wettability of reservoir rocks saturated with oil and water is one of the most important factors influencing petrophysics and oil recovery. Minerals with different wettability constitute the overall heterogeneous wettability in rocks. Variations in sample composition can be detected by nuclear magnetic resonance (NMR) measurements. In this paper, the method of using the magnetic susceptibility contrast between rock skeleton and saturated fluid to estimate wettability is proposed. The theoretical feasibility was firstly analyzed, and then the internal gradients caused by magnetic susceptibility contrasts were employed to interpret wettability alteration before and after ageing process in rocks. It was discovered that water and oil in the same pores experienced different internal gradients after ageing, which were associated with the differences in magnetic susceptibility contrasts. After that, the free induction decay measurement was performed to acquire magnetic susceptibility contrasts of artificial sandstone samples with the intermediate-wet condition. A refined NMR wettability index was presented and correlated with the Amott wettability tests. The experimental results demonstrate that the new method for determining wettability is feasible.

The pelletization and torrefaction of coffee grounds, garden chaff and rapeseed straw

Waste biomass pelletization is a suitable process for obtaining energy dense solid fuel. If the pellets are further processed by torrefaction, both their qualitative and energy parameters are changed. Therefore, the objective of this study is to investigate the effect of the torrefaction process on pellets made from coffee grounds, garden chaff and rapeseed straw. Mechanical parameters, such as the pellet durability index, the wettability index of the pellets, their water moisture resistance, hardness, or specific and bulk density were determined for evaluation. Furthermore, pellet energy parameters such as the heat of combustion, calorific value, or elemental analysis were compared. Pelletization of the above-mentioned waste biomass and the torrefaction of the pellets were carried out in pilot plants. The first results showed that the torrefaction process for all samples increased the values of the heat of combustion or the values of the carbon content. The energy value of the pellets increases. The higher heating value of torrefied coffee ground pellets reached 26 MJ kg−1. The ash content also increases with these values. A simple energy balance has been carried out. Therefore, the study shows an insight into the energy use of coffee grounds and chaff from the garden compared to the results of the rapeseed straw pellets for the pelletization and torrefication process.

Wettability variation and its impact on CO2 storage capacity at the Wyoming CarbonSAFE storage hub: An experimental approach

Meeting global and national net zero carbon emission targets will require geologic carbon disposal. The U.S. Department of Energy (DOE) has accordingly funded significant research in this area, including the Wyoming CarbonSAFE project at Dry Fork Station (DFS) in Campbell County, Wyoming. This work studied wettability on micro- and macro-scales, CO2 storage potential, and the correlation between the two to support the Wyoming CarbonSAFE project’s subsurface assessment. During the study, a target formation’s wettability was found to affect how much CO2 can be stored in a given formation.In this study, representative rock samples were selected from the target storage formations— Lakota, Hulett, and Minnelusa—based on the heterogeneity of the lithology, permeability, and porosity of the respective formations. The rock samples are all fine-grained sandstone with variable cementation and bedding structure, including different scales of laminated bedding. The porosity and permeability vary within the range of 9.0–14.3% and 0.1–28.9 mD, respectively. These rock samples were prepared for the micro-scale wettability (contact angle measurement), macro-scale wettability (wettability index derived from unsteady-state flow characterization for the core plugs), and CO2 storage evaluation. The macro-scale experiments suggested that wettability appeared to dominate the CO2 storage potential performance during the drainage process, where less water-wet behavior promoted higher CO2 storage potential. The micro-scale wettability tests showed that the rock samples at the studied reservoir conditions behaved water-wet and became more water-wet as pressure increased. This kind of wettability change discourages further CO2 storage potential yet benefits the CO2 residual trapping as the CO2 injection proceeds for the studied area. The results allow the recommendation of the best reservoir candidate for storage based on wettability that affects CO2 storage. The work presented in this study provides valuable insights into wettability’s effect on the CO2 storage capacity and wettability’s importance when identifying the optimal CO2 storage formation to meet the project’s goals.