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为了满足市场需求，提升棉籽粕利用价值，结合实际生产情况，采用单因素控制变量法，调整生产工艺中关键控制参数如原料棉仁中的含壳率、甲醇溶液萃取工艺参数以及成品粉碎筛分条件等，确定了分别以含壳率为2%和5%的棉仁为原料的高蛋白脱酚棉籽粕生产工艺。当原料含壳率为2%时，适宜的萃取工艺为浸泡萃取,料液比1∶ 3,浸泡萃取脱酚时间 30 min，甲醇溶液萃取梯度60%-70%-80%-90%，共萃取4次，残油控制在0.7%以下，蒸脱烘干控制水分在5%以下。原料含壳率为5%时，适宜的萃取工艺为淋液萃取，料液比1∶ 2，甲醇溶液萃取梯度70%-70%-70%-70%-80%-90%，共萃取6次，残油控制在0.7%以下，蒸脱烘干控制水分在5%以下。采用上述两种方法，可得到粗蛋白质含量在70%以上、游离棉酚含量满足企业内控指标要求（≤400 mg/kg）的脱酚棉籽粕。 To meet the market demand, enhance the utilization value of cottonseed meal,combined with the actual production situation, the single factor variable control method was used to adjust the key control parameters, such as the shell content of cottonseed kernel, methanol solution extraction process parameters and the cracking and screening conditions of finished products, to determine the production process of high protein degossypoled cottonseed meal using cottonseed kernel with 2% and 5% shell content as material. When the shell content of the raw material was 2%, the appropriate extraction process was soak extraction, material-liquid ratio 1∶ 3, soak extraction time 30 min, methanol solution extraction gradient 60%-70%-80%-90%,extraction times 4, the residual oil of cottonseed meal below 0.7%, and the moisture after desolventing and drying below 5%. At 5% shell content,the appropriate extraction process was liquid-liquid extraction, material-liquid ratio 1∶ 2, methanol solution extraction gradient 70%-70%-70%-70%-80%-90%, extraction times 6, the residual oil of cottonseed meal below 0.7%，and the moisture after desolventing and drying below 5%. Using these two methods, degossypoled cottonseed meal with crude protein content above 70% can be obtained with content of free gossypol meeting the requirements of internal control index (≤400 mg/kg).

The oil reservoirs of the metamorphic rocks in Bohai Bay have geological characteristics such as low matrix porosity and permeability, developed natural microfractures, which result in the injection water rapidly advancing along fractures, a fast increase in the water content, and difficulties in extracting the remaining oil. In order to reveal water channeling and the residual oil formation mechanisms in fractured low-permeability reservoirs and solve the water channeling problem, we first analyzed the reservoir development status, then studied the formation mechanism of residual oil using a microfluidic chip device, and formed a method of hierarchical control to effectively control the water channeling problem of fractured reservoirs and maximize the displacement of residual oil. The results show that (1) Due to the low permeability of the reservoir matrix, a large amount of injected water flows along the fracture channel, which leads to the long-term high water cut of some oil wells and the retention of a large amount of crude oil in the matrix. (2) The results of microfluidic experiments show that the distribution of residual oil after water flooding mainly includes five types: blind end of the pore throat, columnar, cluster, flake and film, and residual oil. Among them, sheet-like and clustered residual oil are dominant, accounting for 75~85% and 10~13%, respectively. (3) Based on the characteristics of fracture development in buried-hill reservoirs, a hierarchical control technology of "gel particle + liquid crosslinked gel system" is established. The field application effect predicted that the input–output ratio was 1:3. This study provides a reference for the comprehensive treatment of water channeling in the same type of offshore fractured low-permeability metamorphic rock reservoirs. [ABSTRACT FROM AUTHOR]

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This study delves into the micro-occurrence states and enrichment mechanisms of residual oil, pivotal for advancing the production from tight sandstone reservoirs, particularly from the Chang 8 Member of the Upper Triassic Yanchang Formation, Ordos Basin. Through an analysis of 23 core samples, employing high-pressure mercury injection, field emission scanning electron microscopy, thin section, and X-ray diffraction techniques, distinct reservoir types were categorized. The utilization of environmental scanning electron microscope, multi-solvent continuous extraction, and an oil components separation system facilitated an intricate analysis of residual oil micro-occurrence states and their subsequent effects on porosity and permeability reduction across varying reservoir types. The findings accentuate the integral role of reservoir type in determining residual oil distribution within tight sandstone reservoirs. Favorable pore throat sorting and connectivity in specified reservoir types are identified as conducive to residual oil enrichment with a higher concentration of light components. In contrast, elevated carbonatite and clay content in other reservoir types leads to adsorption of heavy components, disrupting pore throat connectivity, and impeding crude oil filling. The varied interactions between oil and rock, oil–oil, and pore throat sealing significantly impact the distribution of oil components of residual oil, culminating in a notable reduction of porosity and permeability by 2.63% and 0.197 mD, with corresponding reduction rates of 27.19% and 46.69%, respectively. The insights derived from this study furnish a theoretical foundation for augmenting tight oil recovery and comprehending the enrichment mechanism of residual oil driven by the heterogeneity of tight sandstone reservoirs. [ABSTRACT FROM AUTHOR]

Abstract This study delves into the micro-occurrence states and enrichment mechanisms of residual oil, pivotal for advancing the production from tight sandstone reservoirs, particularly from the Chang 8 Member of the Upper Triassic Yanchang Formation, Ordos Basin. Through an analysis of 23 core samples, employing high-pressure mercury injection, field emission scanning electron microscopy, thin section, and X-ray diffraction techniques, distinct reservoir types were categorized. The utilization of environmental scanning electron microscope, multi-solvent continuous extraction, and an oil components separation system facilitated an intricate analysis of residual oil micro-occurrence states and their subsequent effects on porosity and permeability reduction across varying reservoir types. The findings accentuate the integral role of reservoir type in determining residual oil distribution within tight sandstone reservoirs. Favorable pore throat sorting and connectivity in specified reservoir types are identified as conducive to residual oil enrichment with a higher concentration of light components. In contrast, elevated carbonatite and clay content in other reservoir types leads to adsorption of heavy components, disrupting pore throat connectivity, and impeding crude oil filling. The varied interactions between oil and rock, oil–oil, and pore throat sealing significantly impact the distribution of oil components of residual oil, culminating in a notable reduction of porosity and permeability by 2.63% and 0.197 mD, with corresponding reduction rates of 27.19% and 46.69%, respectively. The insights derived from this study furnish a theoretical foundation for augmenting tight oil recovery and comprehending the enrichment mechanism of residual oil driven by the heterogeneity of tight sandstone reservoirs.

The displacement of residual oil by water flooding in porous media is an important mechanism of enhanced oil recovery in many sandstone reservoirs. Nonetheless, our basic understanding of the influence of complex pore geometries of natural porous media on fluid distribution is still incomplete. Herein, two-phase flow simulations were performed to investigate the pore-scale dynamics of imbibition in a heterogeneous sandstone rock sample. Furthermore, the relationship between residual oil distribution and pore structure parameters was quantitatively characterized based on a pore-throat segmentation method. The findings suggest that the pore-scale displacement and snap-off processes have a strong dependence on the coordination number and aspect ratio. The entrapment and remobilization of oil clusters were also analyzed under continuous and discontinuous displacement modes. In addition, a new quantitative method to evaluate the displacement potential and mobilization pattern of remaining oil was presented and discussed. Statistical analysis revealed that the development of sub-pathways and the suppression of snapoff are responsible for the decrease in residual oil saturation with increasing capillary number during water injection. Moreover, the connected residual oil clusters trapped in pores with high coordination number prefer to be displaced and produced. Finally, the displacement modes with different capillary numbers under different initial oil distributions were evaluated to explain the effect of pore structure. By incorporating these correlations of displacement events with pore-throat geometry, existing predictive models can be improved, which could be helpful for the fine tapping of highly disconnected remaining oil in sandstone reservoirs. [ABSTRACT FROM AUTHOR]

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Relevance. The fact that with the help of modern methods of increasing oil recovery, it is possible to extract no more than 34 % of oil from the initial recoverable reserves. Therefore, modernization of technologies for tertiary impact on the reservoir as one of the possible ways of developing this area is required. It is possible to use nanoparticles in order to increase the oil recovery coefficient by displacing residual and hard-to-recover oil. Technologies with the use of nanoparticles have a number of significant advantages over the already traditional polymer, alkaline and surfactant flooding. Nanofluidic flooding allows increasing the oil recovery coefficient. The paper considers the mechanisms of action of nanoparticles contributing to oil recovery, the relationship of the effectiveness of flooding from the reservoir temperature, pH, water mineralization and wettability of the reservoir rock surface. These mechanisms are required for identifying limitations of the applicability of nanofluids, the possibility of their modification, in order to improve the properties and eliminate the disadvantages of nanofluid flooding. The effect of the chemical nature of nanoparticles, their size, surface charge, isoelectric point and concentration on rock, reservoir fluids and the efficiency of hydrocarbon extraction is considered in detail. Attention is also focused on the latest modern trends in the development of nanofluidic flooding technology. Aim. To conduct a comprehensive analysis of nanofluidic flooding as a method of increasing oil recovery. Objects. Chemical methods of enhancing oil recovery, nanofluidic flooding. Methods. Analysis of current publications on the research topic. Results. The factors influencing the effectiveness of the use of nanofluids as a method of increasing oil recovery and the mechanisms of the impact of nanoparticles on oil reservoirs are formed, promising directions for the development of nanoparticle technology are identified.

The threshold values of CO2 gas stripped off membranous residual oil from the pore walls are not clear under different temperatures, pressures and wettability conditions. The extent to which temperature, pressure and wettability influence CO2 flooding for enhancing the recovery of residual oil in membranous formations also remains uncertain. Therefore, further quantitative characterization is entailed. In this study, the molecular dynamics method was employed to explore CO2 flooding under different temperatures, pressures and wettability conditions, aiming to enhance the production of membranous residual oil. The results reveal that the interaction energy between CO2, decane molecules and pore walls exhibits a decrease with increasing temperature and an increase with increasing pressure, respectively, in distinct wettability scenarios. When the temperature was at or below 363 K and the pressure was not lower than 40 MPa, CO2 gas could detach the membranous residual oil from the pore walls in the water-wet systems. When the temperature was equal to 363 K and the pressure remained under 40 MPa, or the temperature surpassed 363 K, CO2 gas failed to detach the membranous residual oil from the pore walls in the water-wet systems. For the mixed-wet and oil-wet systems, CO2 molecules could not detach the membranous residual oil from the pore walls. The hierarchy of influence regarding temperature, pressure and wettability on the competitive adsorption capacity of CO2 and decane molecules on the pore walls emerged as follows: wettability > temperature > pressure. The findings of this study offer valuable insights into the application of CO2 gas flooding for the exploitation of membranous residual oil on pore walls.

How to effectively predict the distribution law of remaining oil resources is an important work to increase the oil field production potential of old wells. Taking the Chang 2 Member of the Tiebiancheng area, Jiyuan oilfield, northwestern Ordos Basin as an example, the remaining oil distribution characteristics of the main reservoir were systematically studied using core, thin section, electron microscope, physical properties and numerical simulation methods. The study shows that the Chang 21 3-2 and Chang 21 3-3 layers are the main oil-producing formations with average thicknesses of 12. 2 m and 11. 1 m, respectively. The main oil-producing layers have the porosity range between 12% and 18% and the permeability of less than 8 mD. According to the principle of facies control, the physical property model and fluid model of the main production layers are established. Furthermore, the reservoir numerical simulation was carried out using the ECLIPSE Software. The historical fitting results show that all the production indexes are in good agreement with the actural data, and the simulation results are reliable. The numerical simulation results show that the remaining oil distribution is affected by sand body boundary, physical property difference and injection-production relationship. However, due to the difference of reservoir properties, the effect of water injection is not uniform, resulting in local remaining oil enrichment. The remaining oil is mainly distributed at the boundary of the sand body. There is no well pattern control in these areas, so the degree of water flooding is low and the remaining oil is rich in these areas. As for the areas on both sides of the high permeability zone between injection and production wells, the oil well is flooded quickly and the oil well production decreases rapidly because the injected water breaks out along the high permeability zone between injection and production wells. At the same time, due to the small affected area and uneven water flooding, the areas on both sides of the hyperpermeability zone did not get effective water flooding, forming the remaining oil-rich area. Therefore, the remaining oil accumulation is obviously controlled by microfacies, physical properties, water injection and well pattern factors. [ABSTRACT FROM AUTHOR]

Feeding on crude oil and activator in porous medium, microbes remain active on the Oil-water interface under simulated reservoir conditions. At the same time, microbes degrade the residual oil and change the wettability of pore wall. Consequently, the displacement exhibits a decrease of 51.86% in membrane residual oil and an increase of 17.44% in recovery compared with water flooding. The Geobacillus stearothermophilus producing bio-emulsifier and its metabolic products can effectively emulsify reservoir crude oil and reduce the oil-water interfacial tension. In the end and the formed emulsion featured high viscosity can improve the oil flow rate and expanded wave volume of injected fluid. Correspondingly, the cluster-like, columnar residual oil were reduced by 64%, 68% respectively. In the micro porous test cell, the in-situ cultured microbes rely on specific life activities (interfacial tropism and in situ metabolism, etc.) to strip the residual oil off the wall of orifice deep inside the blind-ends, which cannot be achieved by the exogenous injection method. After the in-situ microbial culture process, the residual oil in deep blind-ends was reduced by about 47%, and the recovered oil was increased about 15% compared with exogenous injection method. [ABSTRACT FROM AUTHOR]

Fractured-vuggy reservoirs are mainly composed of three types: underground rivers, vugs, and fractured-vuggy structures. Based on the similarity criterion, a 3D model can truly reflect the characteristics of the multi-scale space of a fractured-vuggy reservoir, and it can reflect fluid flow laws in the formation. Water flooding, gas flooding, and gel foam flooding were carried out in the model sequentially. Based on gas flooding, the enhanced recovery ratio of gel foam flooding in the underground river was approximately 12%. By changing the injection rate, the average recovery ratio of nitrogen flooding was 6.84% higher than that of other injection rates at 5 mL/min, and that of gel foam flooding was 1.88% higher than that of other injection rates at 5 mL/min. The experimental results showed that the gel foam induced four oil displacement mechanisms, which selectively plugged high-permeability channels, controlled the mobility ratio, reduced oil-water interfacial tension, and changed the wettability of rock surfaces. With different injection-production methods, gel foam flooding can spread across two underground river channels. Two cases of nitrogen flooding affected one underground river channel and two underground river channels. By adjusting the injection rate, it was found that after nitrogen flooding, there were mainly four types of residual oil, and gel foam flooding mainly yielded three types of remaining oil. This study verified the influencing factors of extracting residual oil from an underground river and provides theoretical support for the subsequent application of gel foam flooding in underground rivers. [ABSTRACT FROM AUTHOR]

The Baise Basin is a Paleogene pull-apart basin with numerous strike-slip faults which are not favorable for hydrocarbon preservation. The Nadu Formation, research object of this paper, is generally rich in oil and contains a large number of high-angle joint fissures. Analyzing the origin of residual oil in high-angle joint fissures can reveal the hydrocarbon migration and accumulation characteristics of the pull-apart-type basins. Molecular geochemical composition characteristics of crude oil and oil source of the Nadu Formation were discussed based on the saturated hydrocarbon biomarker compound and stable carbon isotope distribution of n-alkanes. The studied samples were selected from four members (E2n1, E2n2, E2n3up, and E2n3low) of the Nadu Formation. The results suggested that the average oil content of E2n1 fissures is 0.32 mg/cm2, and the oil distribution is not uniform. The distribution of oil on the fissures of E2n2 and E2n3 is uniform and complete, and the oil content reaches 0.53 mg/cm2. The oil in the joint fissures of the Nadu Formation is heavy, as the light hydrocarbon is seriously lost during migration. Thus, the oil in the joint fissures is residue after crude oil loses light components during migration. By comparing the molecular biomarker characteristics and stable carbon isotopic compositions, crude oil of the Nadu Formation can be classified into three categories: E2n1, E2n2 + E2n3up, and E2n3low. The E2n1 oils have the lowest maturity and are sourced from the E2n1 source rocks. Moreover, the maturity of E2n2 and E2n3 samples are relatively high. Biomarker and carbon isotope characteristics of the E2n2 and E2n3up oils are similar, indicating that they are derived from the E2n2 + E2n3up source rocks. The E2n3low oils are the mixture of the crude oil generated from the E2n3up source rocks and the E2n3low source rocks. Results presented show that the residual oil of high-angle joint fissures in the Nadu Formation is contributed by adjacent source rocks. The crude oil discharged from the Nadu Formation can only migrate upward along high-angle joints in a short distance, and the migration distance is usually less than 5 m. In conclusion, although the Nadu Formation has developed a large number of high-angle joint fissures, crude oil in the Nadu Formation has not vertically migrated for long distance along the joint fissures. The well-preserved fractures as important shale oil storage spaces indicate that the Nadu Formation has good shale oil exploration potential. The results may provide insights into the origins of hydrocarbons in the Nadu Formation from the Baise Basin and enhanced knowledge for optimizing future exploration and production. [ABSTRACT FROM AUTHOR]

Various applications of oil palm empty fruit bunches (OPEFB) would be hindered by the presence of residual oil. This study aimed to remove and recover the residual oil from OPEFB using an integrated system, high pressure water spray system (HPWSS). The performance of the HPWSS was evaluated at different temperatures and water pressures, and the residual oil collected was recovered through water shaking method and tested for biodiesel application. A maximum of 84.9% of residual oil was removed by HPWSS at 60 °C and 8960 kPa and the highest residual oil recovery of 58.8% was observed at 95 °C, using power shaking 5 and 90% of dilution. The following ranges of deterioration of bleachability index (DOBI), free fatty acid (FFA), and peroxide value (PV) for the residual oil were 1.21 to 2.67, 7.11 to 10.4%, and 4.85 to 7.56, respectively. Biodiesel with different blends of recovered residual oil (5%, 10%, and 15%) showed lower values (9.87, 9.57, and 9.56 Nm) of brake torque as compared with diesel (10.89 Nm). Overall, this study showed the potential of HPWSS to obtain an acceptable quality of residual oil from OPEFB to be used in any value-added product generation.

This study aimed to produce Rhizopus oryzae whole-cells having high lipolytic activity. The hydrolytic activity of 558.99 U.g−1 and total lipase activity of 7440.17 U was obtained in 72 h of cultivation using 30 g.L−1 of canola oil. Optimal activity was observed at pH 7.5 and 30 °C. Kinetic parameters were determined through olive oil hydrolysis (Km = 59.96 mM, Vmax = 344.09 μmol.g−1.min−1). Thermal inactivation constant and half-life were 0.15 h−1 and 4.62 h at 50 °C. Hydrolysis of vegetable oils achieved 80% yield in 24 h. These results suggest that the biocatalyst shows the potential to produce free fatty acids of great industrial interest.

Pore and permeability are distributed discontinuously and unevenly in the dominant sedimentary model of the lateral accretion body inside the meandering river point bar of the Fuyang reservoir of the Yushulin oilfield. Based on the water flooding experiments of field core samples, the influence of pore permeability conditions on residual oil distribution type and water cutting rate was studied by using the microscopic visualization technology enabled through a photolithographically fabricated glass model. It is found that the residual oil in samples shows five discontinuous types, which are cluster, columnar, oil droplet, membrane, and blind end. In the stages with low, medium, and high water cutting rates, the proportion of clustered residual oil in the samples with different permeability is high, reflecting the situation that it is difficult for injected water to spread widely in tight oil reservoirs. With the decrease of permeability, the proportion of membrane and blind end residual oil gradually increases, which indicates that the thin pore throat can produce large restrictions on residual oil, resulting in residual oil enrichment. At the same time, the water flooding experiment was carried out by changing the displacement direction and periodic water injection. It was found that changing the displacement direction was beneficial to the recovery of residual oil in the thin pore throat and avoided the dominant seepage of injected water in the big pore throat, and the recovery rate was increased by more than 2.14%. Periodic water injection, which was conducive to adjusting the displacement pressure difference, reduced the constraining force of the throat on residual oil and increased the recovery rate by more than 3.98%. The actual well area with closed coring wells and dynamic production data is preferred for the application of experimental research results. Changing displacement direction and periodic water injection increased the residual oil recovery by more than 3%. [ABSTRACT FROM AUTHOR]

Copyright of Chemical Engineering (China) / Huaxue Gongcheng is the property of Hualu Engineering Science & Technology Co Ltd. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The development of fractured-vuggy carbonate reservoirs is extremely difficult because of the complex fractured-vuggy structure and strong heterogeneity. Foam flooding is a potential enhanced oil recovery (EOR) technology in fractured-vuggy carbonate reservoirs. Based on the similarity criterion, three types of 2D visual physical models of the fractured-vuggy structure were made by laser ablation technique, and a 3D visual physical model of the fractured-vuggy reservoir was made by 3D printing technology. Then the physical analog experiments of foam flooding were carried out in these models. The experimental results show that foam can effectively improve the mobility ratio, control the flow velocity of the fluid in different directions, and sweep complex fracture networks. The effect of foam flooding in fractures can be improved by increasing foam strength and enhancing foam stability. The effect of foam flooding in vugs can be improved by reducing the density of the foam and the interfacial tension between foam and oil. Three types of microscopic residual oil and three types of macroscopic residual oil can be displaced by foam flooding. This study verifies the EOR of foam flooding in the fractured-vuggy reservoir and provides theoretical support for the application of foam flooding in fractured-vuggy reservoirs. [ABSTRACT FROM AUTHOR]

The objective of this research was to evaluate the quantitative and qualitative characteristics of the carcass and meat of lambs fed with different types of oil. Thirty male, uncastrated, mixed breed (Santa Inês × Dorper) sheep were used in this experiment and were distributed in random blocks with three treatments and 10 replicates per treatment, where each animal represents a replicated experimental unit. The three treatments were the following experimental diets: soybean oil in natura; soybean oil after use in frying, and palm oil (Elaeis guineensis). The oils were incorporated into the sheep diets at a level of 4%. Carcasses were evaluated for hot and cold yield, loss due to cooling, finish, conformation, internal fat concentration, morphometric measurements, tissue composition, and commercial cuts. The addition of soybean oil in natura, residual soybean oil from frying, and palm oil to the sheep diets did not alter any of the evaluated characteristics, which therefore can be interpreted as favoring the use of any of these three oils as a supplement to their diet, and the three oils imparted good characteristics to the carcasses and the meat.

The marlelimestone rhythmic strata of the Permian Maokou Formation have been identified as hosts of unconventional gas reservoirs with "sourceereservoir" integration. The lack of research on the pore structure evolution of organic-rich carbonate rock restricts gas exploration of these strata. Here, pyrolysis experiments were performed on the Mao-1 carbonate to simulate hydrocarbon generation, expulsion and diagenesis in gray marl from low maturity to overmaturity. The pore structure of this marl is dominated by mesopores and macropores, and the proportion of macropores increases gradually with temperature. The macropores are mainly pores in the organic matter and shrinkage microcracks. Additionally, micropores and mesopores, dominated by clay mineral interlayer pores and pyrite intergranular pores, are developed in the high mature stage and subsequently compressed in the overmature stage. The main contributors to the specific surface area are micropores and mesopores, which are conducive to natural gas adsorption. After the same pyrolysis treatment, the available porosity of grey marl is higher than that of marine/lacustrine shales, and exhibits an obvious decrease in the low mature emature stage. These suggest that the abundant residual oil generated blocked the organic and inorganic pores in the gray marl, providing a pivotal material foundation for the gas generation. Micropores and mesopores developed during the high mature stage ensure the gas accumulation and preservation. The above indicate the organic-rich carbonate at the high matureeovermature stage (Ro = 1.7%e2.5%) in the Sichuan Basin may be a favorable exploration horizon for unconventional oil and gas. [ABSTRACT FROM AUTHOR]

Halite and gypsum minerals in saline shale make the retention mechanism and chemical fractionation of residual oil unique. The Dongpu Depression in North China is a typically saline lacustrine basin with developing halite and gypsum. The effect of gypsum minerals on residual oil content and chemical fractionation remains unclear. In this study, shale samples with different gypsum contents were used in organic geochemical experiments, showing that the high total organic matter (TOC) content and type II kerogen leads to a high residual oil content, as shown by high values of volatile hydrocarbon (S1) and extractable organic matter (EOM). XRD and FE-SEM result indicate that the existence of gypsum in saline shale contributes to an enhanced pore space and a higher residual oil content in comparison to nongypsum shale. Additionally, the increase in the gypsum mineral content leads to an increase in the saturated hydrocarbon percentage and a decrease in polar components percentage (resins and asphaltene). Furthermore, thermal simulation experiments on low-mature saline shale show that the percentage of saturated hydrocarbons in the residual oil is high and remains stable and that the storage space is mainly mesoporous (> 20 nm) in the oil expulsion stage. However, the saturated hydrocarbons percentage decreases rapidly, and oil exists in mesopores (> 20 nm and < 5 nm) in the gas expulsion stage. In general, gypsum is conducive to the development of pore space, the adsorption of hydrocarbons and the occurrence of saturated hydrocarbon, leading to large quantities of residual oil. The data in this paper should prove to be reliable for shale oil exploration in saline lacustrine basins. [ABSTRACT FROM AUTHOR]

Internal combustion engine research predominantly focuses on routes to lower emissions to meet various emission legislation. Lower emissions can be achieved with increased fuel efficiency and less lubricant throw off/lubricant combustion in the piston ring zone. These are all dependent on the oil film that forms between the liner and piston components. This article details the use of ultrasonic sensors to study the lubricant film thickness between the engine liner and piston rings/skirt in a fired diesel two-cylinder YTR engine. The testing regime covered a series of engine speeds and loading levels and found the minimum oil film thickness to vary from 1 to 3.5 μm. Spectrograms (time-varying ultrasonic amplitude spectra) have shown a residual oil film on the liner, first present after the skirt moves above the sensor that peaks at 440 μm, which then dissipates until the next oil control ring passage. Start-up and shut-down captures have visualised the build-up and reduction of the film thickness, in which during start-up typically a 2-s interval between the first ring passage and a consistent film thickness was seen. Whilst the shut-down tests showed a lesser variation, anticipated to be due to the oil pump already operating and is, therefore, less subjective to a reduction in engine speed providing a threshold of oil remains on the liner. Measurements like this help to describe how lubrication occurs in the piston ring zone and hence can optimise component design and an oil injection schedule. [ABSTRACT FROM AUTHOR]

In this study, a comparison of the intra-regional variation in the quality of Argan oil and pomace collected from 12 cooperatives in the Essaouira region (Morocco) during the COVID-19 period was carried out. All studied Argan pomaces together with the extraction solvents showed a significant difference (p < 0.05) in the total phenolic compounds, flavonoids, and tannins contents. The proteins, residual oils, total sugars, and total reducing sugars contents in the collected pomaces vary considerably among cooperatives of origin, with maximum averages of 50.45%; 30.05%; 3.82 milligrams of glucose equivalent per gram of dry matter; and 0.53 milligrams of glucose equivalent per gram of dry matter, respectively. Therefore, it is a very valuable ingredient for livestock feed and some cosmetic products that may contain it. The remaining Argan oil content in the pomace varied significantly among cooperatives, ranging from 8.74 to 30.05%. Pomace from traditional extraction recorded the highest content (30.05%), showing that the artisanal and modern extraction processes are not standardized. The measurements of acidity, peroxide value, specific extinction coefficient at 232 nm and 270 nm, and conjugated dienes were carried out in accordance with Moroccan Standard 08.5.090 in order to qualitatively classify all investigated Argan oils. Accordingly, the analyzed oils were categorized as "extra virgin Argan oil," "fine virgin Argan oil," "ordinary virgin Argan oil," and "lampante virgin Argan oil." Therefore, several factors can explain these variations in quality grades, both endogenous and exogenous. Overall, the variation observed in the obtained result allows us to deduce the most significant variables impacting the quality of Argan products and by-products. [ABSTRACT FROM AUTHOR]

After years of development and adjustment, YY Oilfield has entered the stage of high water-cut development. The main reservoirs are flooded seriously and the remaining oil distribution is complex. The main contradictions of reservoir development are transferred from interlayer and plane contradictions to intralayer contradictions. The heterogeneity of reservoir internal structure is the core geological factor that leads to the complicated watered-out form and residual oil distribution in the later stage of oilfield development. Taking the eastern pure oil area of XX District as the research object, this paper determines the description method of residual oil in thick reservoirs, which provides technical support for the follow-up tapping potential of thick reservoirs.

The thermal recovery method of steam flooding is one of the most common development methods for heavy oil reservoirs. However, after multiple rounds of steam injection development, the composition of crude oil and reservoir rock properties have changed greatly, which is unfavorable for the subsequent enhanced oil recovery. It is necessary to study the distribution of the remaining oil after the thermal recovery of heavy oil reservoirs, and clarify the change characteristics of the components of the crude oil under different steam injection conditions. At the same time, the change of porosity and the permeability of the rocks after steam flooding, and its influence on oil recovery, are investigated. In this paper, the composition changes of heavy oil before and after steam flooding are studied through experiments and numerical simulation methods. A numerical model is established to study the retention characteristics of heavy components in heavy oil reservoirs by the CMG software. The effects of different steam injection conditions, and heavy oil with different components on the residual retention of heavy components, are compared and studied. The changes of rock physical properties in heavy oil reservoirs after steam flooding is clarified. The results show that after steam flooding, the heavy components (resin and asphaltenes) of the recovered oil decrease, and the heavy components in the formation increase in varying degrees. With the increase of heavy components in the crude oil, the remaining oil in the formation increases after steam flooding, and the retention of heavy components increases; after steam flooding, the stronger the rock cementation strength, the higher the degree of reserve recovery, and it is difficult to form breakthrough channels; the greater the steam injection intensity, the earlier to see steam breakthrough in the production well, and the lower the degree of reserve recovery. The research reveals the changes of heavy oil components and rock properties after steam flooding, providing support for the subsequent enhanced oil recovery. [ABSTRACT FROM AUTHOR]

Nowadays, the utilization of non‐conventional oil resources has become an increasingly attractive solution for producing valuable chemicals and materials due to the depletion of conventional oil resources. Plasma technology, powered by renewable energy sources, provides a potential way to convert low‐grade residual oil into lighter hydrocarbons in an environmentally friendly fashion. This study has developed a laboratory‐scale plasma pyrolysis system to investigate the impacts of residual oil characteristics and operating variables such as residual oil‐specific enthalpy, arc gas flow rate, arc gas composition, quenching, and plasma configuration. The results show that the higher specific enthalpy of the residual oil leads to higher yields of C1, C2, and H2, particularly C2H2. An increment in the arc gas flow rate improves the pyrolysis impact; however, an excessively high arc gas flow rate lowers the thermal plasma jet's temperature, causing a limited pyrolysis effect. In the composition of arc gas, the increasing concentration of H2 can enhance the specific enthalpy and improve carbon conversion from residual oil to gas products, both of which result in a higher yield of light gases. Furthermore, ethane gas has been used as a quenching medium after plasma pyrolysis. The results reveal that ethane can be cracked into ethylene and other products by taking full use of the heat energy of the gas. Meanwhile, the sharp decrease in the gas temperature inhibits the further pyrolysis of the main valuable products. [ABSTRACT FROM AUTHOR]

In recent years, as an important part of unconventional resources, the effective development of shale oil has been a key area of research in petroleum engineering. Given the widespread availability and low cost of air, the evaluation of air injection in shale reservoirs is a topic worth exploring. This paper analyzes the production performance of different methods of air injection development in the shale reservoir, including air flooding and air huff and puff (HnP), based on full-diameter core air injection experiments. Meanwhile, the characteristics of the residual oil and produced oil are revealed by forming a systematic evaluation method that includes nuclear magnetic resonance (NMR), laser scanning confocal microscopy (LSCM), and gas chromatographic (GC) analysis. The results show that air flooding development is characterized by early gas breakthrough, long oil production period, and "L" shape oil production decline; while air HnP is characterized by first producing gas and then producing oil, rapid oil production, and high oil recovery efficiency in the first round. Compared with air flooding, the replacement efficiency of the first round of air HnP is significantly higher, demonstrating higher feasibility of air HnP in the early stages of development, although the cumulative recovery of three rounds air HnP (17.17%) is lower than that of air flooding (23.36%). The large pores (T2 > 10 ms) are the main source of air injection recovery, while the residual oil is mainly concentrated in the medium pores (1–10 ms). Air injection development has a higher recovery factor for light components ( C 15 − ), resulting in a higher level of heavy components in the residual oil. This paper discusses the feasibility and development effectiveness of air injection in shale oil reservoirs, and its development characteristics are further clarified. [ABSTRACT FROM AUTHOR]

Extensive asphalt pavements have persisted along >25 km (km) of shoreline on Abu Ali Island, on the Arabian (Persian) Gulf coast of Saudi Arabia, reportedly stranding as a result of the 1983–1985 Nowruz oil spills. A study was conducted in October 2020 to support development of a remediation plan. Cross-shore transects were surveyed at 100 m intervals and 1434 shovel test pits were dug to determine oil type, thickness, and depth of burial. Oiling of any description was observed at 76% of the pits. Using 15 diagnostic biomarker ratios, only 5 of the 94 oiled samples from Abu Ali Island in 2020 likely contain other oils. Data on historical spills were identified from the literature. Based on chemical biomarker data for potential source oils in the northern Arabian (Persian) Gulf, the diagnostic ratio for the biomarkers 18a-22,29,30-Trisnorneohopane (Ts) and 17a(H)-22,29,30-Trisnorhopane (Tm) for the 94 samples only matched one Iraq crude oil. No large individual spills of Iraq crude oil were identified in the literature or spill databases, although releases of both Kuwait and Iraq crudes were reported for the 1991 Gulf War oil spills. However, oil residues from Abu Ali did not match most prior samples of Saudi shoreline oiling from the Gulf War oil spills, which largely consisted of spilled Kuwait crude. Though we cannot definitely conclude that the majority of the residual oil on Abu Ali Island delineated during the 2020 survey is oil from the Nowruz oil spills, because there is no source oil from these spills, we use a weight of evidence approach to say that it is highly likely that the majority of the residual oiling is from the Nowruz spills. [ABSTRACT FROM AUTHOR]

The results of core displacement experiments show that increasing the water drive velocity when it is bigger than the limit value can effectively reduce the residual oil saturation and improve the oil displacement efficiency under the same PV. However, the existing commercial simulators (Eclipse, CMG et al.) cannot simulate the effect of water velocity on the relative permeability curve in the process of numerical simulation.In this article, capillary number (Ca), defined as the dimensionless ratio of viscous force to capillary force, is used to characterize the relationship between water drive velocity and residual oil. Second, a new Boltzmann (BG) equation is proposed to match the nonlinear relationship between Ca and residual oil. The BG equation is a continuous function, which is very beneficial to the stability of numerical calculation. Finally, a new reservoir numerical simulator is established which captures the dynamic variation of residual oil saturation with water drive velocity in a water flooding reservoir based on the black oil model. The new simulator was verified by comparing it with the commercial reservoir simulator ECLIPSE and experimental data. The simulation results show that compared with the common model, the model considering the dynamic variation of residual oil saturation with water drive velocity reduced the residual oil saturation near the main flow line after enhanced injection rate. The oil phase flow capacity in the model is enhanced, the water cut is decreased, and the oil recovery rate is higher. The history matching of the S oilfield in Bohai Bay is achieved with the new simulator, and the history matching accuracy is obviously higher than that of Eclipse. The findings of this study can help with a better understanding of the distribution law and flow law of remaining oil in the high water cut stage of the reservoir and have good theory and application value for water flooding offshore oilfields.

Oilfield-produced water (PW) can be cleaned using a variety of techniques. However, traditional methods are often expensive and can generate secondary waste that pollutes the environment. In addition, PWs contain highly stable micronized dispersed oil, which makes conventional treatment ineffective in meeting regulatory requirements. As a result of their unique properties, magnetized nanoparticles can effectively remove emulsified and dissolved oil from PW. This study aims to evaluate the residual oil removal efficiency of bare maghemite (γ-Fe2O3) nanoparticles in treating oilfield-produced water (produced water).Several techniques for manufacturing maghemite nanoparticles were evaluated to select one that is both cost-effective and produces high-quality nanoparticles. After manufacturing nanoparticles with the selected method, the mineral composition and properties of the nanoparticles were determined. Subsequent experiments used synthetic and commercial nanoparticles to treat samples of PWs derived from oil and gas wells. By measuring the oil content of PW before and after treatment, the removal efficiencies of the nanoparticles were determined. Nanoparticles were recovered from treated PW samples, washed, and reused. Over ten times, they were recycled. The recycling potential of nanoparticles is evaluated by assessing the reduction in oil removal efficiency after recycling. Using fresh nanoparticles, over 98% of residual oil can be removed. Even after recycling more than 11 times, the oil content of treated PW samples was below the disposal limit. However, a slight reduction in the efficiency of the nanoparticles was observed. The reduction could be attributed to their dissolution in water and carryover during the treatment/demulsification operation.

Fractured-vuggy reservoirs are mainly composed of three types: underground rivers, vugs, and fractured-vuggy structures. Based on the similarity criterion, a 3D model can truly reflect the characteristics of the multi-scale space of a fractured-vuggy reservoir, and it can reflect fluid flow laws in the formation. Water flooding, gas flooding, and gel foam flooding were carried out in the model sequentially. Based on gas flooding, the enhanced recovery ratio of gel foam flooding in the underground river was approximately 12%. By changing the injection rate, the average recovery ratio of nitrogen flooding was 6.84% higher than that of other injection rates at 5 mL/min, and that of gel foam flooding was 1.88% higher than that of other injection rates at 5 mL/min. The experimental results showed that the gel foam induced four oil displacement mechanisms, which selectively plugged high-permeability channels, controlled the mobility ratio, reduced oil-water interfacial tension, and changed the wettability of rock surfaces. With different injection-production methods, gel foam flooding can spread across two underground river channels. Two cases of nitrogen flooding affected one underground river channel and two underground river channels. By adjusting the injection rate, it was found that after nitrogen flooding, there were mainly four types of residual oil, and gel foam flooding mainly yielded three types of remaining oil. This study verified the influencing factors of extracting residual oil from an underground river and provides theoretical support for the subsequent application of gel foam flooding in underground rivers.

The paper examines the issues of replacing residual oil from fine pores of oil contaminated soil under gradientless pressure conditions. It was shown that the replacement of residual oil from fine pores of oil contaminated soil can be possible because of their unavailability for displacing water. Therefore, in addition to others, destruction degree of the system of pores and capillaries in aggregated structure of oil contaminated soil is considered as an efficiency criterion of an impact on disperse system in oil flushing process, and optimum destruction - as an optimum degree of these impacts. The aim is solved by using the complex methods of joint chemical, physicalchemical and mechanical impact on structured disperse systems of mineral particles of soil. It was shown that in the same chemical-mineralogical composition of oil contaminated soil the efficiency of its treatment increases with the growth of dispersity of its mineral particles. Increasing methods of their dispersity are related to the impact on various forces connecting mineral particles in a single system of structural formations, such as coagulative, condensationcrystalline, and mixed - coagulative -crystalline macro- and microaggregates. To ensure the possibility of realizing mass exchanging processes under the influence on washing water solution on oil surface it is important to destruct the structure, disperse all aggregates from particles by separating them (breaking of contact) and releasing unevenly distributed immobilized liquid phase (oil and water). Under intense mechanical impacts the bond strength between particles is destroyed using adsorption decrease of structure strength in surface-active medium. In this case, aggregates are destroyed into initial particles and structural bonds are broken. Dispersion (peptization) or spraying of microaggregates can be caused by changing the composition of the dispersion medium, using a chemical method of impact. An example of a chemical method of influencing oil contaminated soil is the displacement of Ca2+ и Mg2+ ions from the exchange complex of clay minerals and their replacement with Na+ ions, which leads to the spraying of water-resistant and true aggregates cemented with calcium and magnesium. Increasing the pH of soil suspension medium to 8.0-8.5 and recharging of electropositive hydrates of Al and Fe oxides leads to the destruction of isoelectric aggregates formed by them with electronegative particles such as silica and clay minerals. In the treatment of oil contamınated soil by washing the surface of mineral particles with washıng water solution to prevent oil resorption and coalescence of its droplets, hydrophilization of soil particles is a determining process. [ABSTRACT FROM AUTHOR]

The fracture-vuggy carbonate reservoir possess strong heterogeneity, and the reservoir space of it is mainly composed of fractures and vugs. After water injection and gas injection development, there is a large amount of remaining oil in the reservoir space. A two-dimensional visual physical model which can characterize the structural characteristics of different fractures and vugs was designed and made according to the geological characteristics of fracture-vuggy carbonate reservoirs in Tahe oilfield. The physical experiments of foam flooding were carried out based on these visualization model. The foam flooding effect and the production mechanism of different fracture-vuggy structures were revealed, and the foam production effect on remaining oil in different displacement stages was clarified. The study shows that foam has excellent mobility control ability and high permeability channel plugging ability. It has a good displacement effect for horizontal, vertical and high-angle fractures, and can effectively improve the oil recovery of fracture-vuggy carbonate reservoirs at different development stages. The existence of filling medium is beneficial to enlarge the foam sweep volume and improve the microscopic oil displacement efficiency. Enhancing the strength and stability of the foam can enhance the ability of the foam to change fluid flow direction. Reduce the density of foam can reduce the interfacial tension and improve the foam flooding recovery in fracture-cave reservoir. The results of laboratory research can provide a theoretical basis for the field application of foam flooding in fracture-vuggy carbonate reservoirs. [ABSTRACT FROM AUTHOR]

Carbonate reservoirs are rich in oil and gas reserves; thus, they have great exploitation potential. Therefore research on the microscopic mechanisms of carbonate reservoirs is of great significance. Based on the thin section images of core castings of typical Well 555 and its pore and fracture features in actual reservoirs, this study designed three kinds of images representing the pore and throat structure of real rocks by applying image stitching and binarization processing methods. A microscopic pore model of carbonate rocks was then established using COMSOL numerical simulation software. The microscopic water flooding characteristics and residual oil distributions of different schemes were observed by designing different fracture development forms. The fractures that developed in parallel main lines showed a more obvious influence on water flooding characteristics compared to fractures that developed in vertical main lines. The cluster residual oil was the main residual oil type in the early stage of water flooding in the pure matrix model. With the progress of water flooding, the continuous cluster residual oil gradually turned into mainly discontinuous porous and columnar residual oils. Vertical mainline fractures reduced the amount of residual oil in clusters and replaced it with columnar residual oil. In contrast, parallel main line fractures expanded the unswept area, with the residual oil appearing in contiguous clusters. This study microscopically analyzed the law and characteristics of water flooding in carbonate reservoirs to provide key theoretical support for enhancing oil recovery.

Asphaltene deposition during CO2 flooding and its effects on oil recovery were experimentally investigated using a high-pressure microscopic porous test cell at reservoir temperature of 80°C and pressures of 2 MPa, 6 MPa, and 10 MPa. CO2 flooding led to significant asphaltene deposition under higher pressures (6 MPa and 10 MPa), while no deposition occurred at 2 MPa. The amount, outset, and particle sizes of deposition were greater under higher pressure. In addition, the significant dynamics of oil/gas interfaces and the simultaneous deposition experimentally indicated that the deposition was closely related to CO2 dissolution. Concerning the oil production, it was pointed out that 48%, 64%, and 38% of the initially existing oil volume have been produced at pressures of 2 MPa, 6 MPa, and 10 MPa, respectively. Sufficient dissolution between oil and gas enhances oil recovery. However, severe asphaltene deposition clogs throats and reduces sweep efficiency and oil recovery. Therefore, oil recovery was positively and negatively impacted by CO2 dissolution and asphaltene deposition, respectively. [ABSTRACT FROM AUTHOR]