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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).

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.

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.

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.

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.

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.

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 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.

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.

A downside of producing oil is that it can never be fully recovered. After the end of a well's life span, the residual oil remaining in the reservoir on average can be over 30%. This residual oil can be extracted using enhanced oil recovery techniques, one of which combusts the oil in the formation where the average reservoir temperature can increase to 400⁰C for light oil and over 600⁰C for heavy oils. This method can become a significant catalyst in solving Pakistan's energy need and increasing power production. This paper aims to estimate the thermal energy production by combusting this residual oil using in-situ combustion by air injection technique. The study deals with the well Kahi-01 located in the upper Indus basin having three formations. The main target is the Hangu formation and its three reservoir blocks. This formation is characterized by its high residual oil percentage of 76-85% at depths of about 1691-1741 meters. The results show that the highest thermal energy output among the three reservoirs was 34.6e6 Megajoules. The highest power output from the binary plant was 38.5e4 Kilowatt hour.

Abstract Background Pollution by waste hydrocarbons on soil and water bodies is an endemic problem in African countries, particularly in Nigeria. This has caused untold hardship and increase in poverty level of the people, due to the pollution of water and land; which had direct impacts on the livelihood of people. Several species of bacteria that can degrade hydrocarbon had been isolated from the root of plants. The aim of this work was to determine the ability of rhizosphere bacteria to degrade spent engine oil (SPO) in the presence of arbuscular mycorrhiza fungus. Results The total aerobic count in the eight treatments ranged between 3.0 × 106 and 1.18 × 108 CFU/g. No significant difference was observed in the total aerobic count among the treatments except when compared with the control experiment (M−C−). Isolated bacteria from the polluted soil samples were identified by 16S rRNA sequencing as Bacillus cereus, Pseudomonas aeruginosa, Bacillus amyloliquefaciens, Lysinibacillus fusiformis, Bacillus enecimensis, and Paraclostridium benzoelyticum. Four of the bacteria were able to utilize spent engine oil effectively to different degrees. However, Lysinibacillus fusiformis biodegraded spent engine oil by 40%, Paraclostridium benzoelyticum by 30% and Bacillus enecimensis by 20% after 28 days of incubation. The infrared analysis result revealed that Lysinibacillus fusiformis (P6) reduced the strong and band of alcohol by 44%, carboxylic acid group by 22% and carbonyl group by 27%, respectively. This study revealed that spent engine oil at a minimum value of 50 mg/kg with arbuscular mycorrhiza fungus in the soil samples resulted in better growth for maize plant and higher total aerobic count. Conclusions It can thus be concluded that arbuscular mycorrhiza fungus positively impacts the ability of rhizosphere bacteria in the degradation of spent engine oil and the growth of maize plant on contaminated soil.

In this paper, the variation of clay minerals and their influence on reservoir physical properties and residual oil before and after ASP flooding are analyzed. The results show that the total amount of clay minerals in reservoirs decreases after ASP flooding in the ultra-high-water-cut-stage reservoirs of the Naner Zone in the Saertu Oilfield, Songliao Basin. Therein, the illite content reduces, while the content of illite smectite mixed-layer and chlorite increases. The content of kaolinite varies greatly. The content of kaolinite decreases in some samples, while it increases in other samples. The clay minerals block the pore throat after ASP flooding. As a result, the pore structure coefficient and the seepage tortuosity increase, the primary intergranular pore throat shrinks, and the pore–throat coordination number decreases. Nevertheless, the dissolution of clay minerals reduces the pore–throat ratio and increases porosity and permeability. The variation of clay minerals after ASP flooding not only intensifies the reservoir heterogeneity but also affects the formation and distribution of residual oil. The residual oil of the oil–clay mixed adsorption state is a newly formed residual oil type related to clay, which accounts for 44.2% of the total residual oil reserves, so it is the main occurrence form of the oil in reservoirs after ASP flooding. Therefore, the exploitation of this type of residual oil has great significance to enhance the oil recovery in ultra-high-water-cut-stage reservoirs.

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 (C15−), 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.

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.

After water flooding, there is much residual oil left in the pores. This cannot be easily displaced, but polymer flooding is able to achieve this. The use of viscoelastic solutions such as polymer can enhance the oil recovery, because it can increase the sweep volume by improving the mobility ratio of polymer solution and oil. The use of viscoelastic solutions can also increase the displacement efficiency of residual oil in the swept area. This article, based on the momentum equation and Oldroyd-B constitutive model, investigates the influences of polymer solution properties on the stress distribution and deformation of residual oil adhering to the walls of micro-channels. The results show that the elasticity and viscosity of the polymer displacing fluid are the factors with the greatest impact on the stress distribution and deformation of residual oil. The stress computation shows that along the direction of flow, the oil film is compressed at both ends, and pulled in the center. This stress distribution helps the oil film to bulge from its center, leading to its deformation and break-up. Furthermore, by increasing the viscosity or elasticity the residual oil is exposed to greater stress and deformation during the displacement process, which is characterized by a large advancing angle, an increasing deformation index and a small receding angle. Comparison of the simulation and experimental results shows a good conformance. Therefore, to displace the oil more efficiently, the polymer solutions need to be more viscous and elastic, which can be achieved by changing their chemical properties. The results clarify the micro-mechanism of polymers displacing residual oil and quantify the influences of the chemical properties of the solution on the stress, deformation and activation of residual oil.

Oil pollution in soil-groundwater systems is difficult to remove, and a large amount of residual oil is trapped in the low permeable layer of the heterogeneous aquifer. Aromatic hydrocarbons in oil have high toxicity and low solubility in water, which are harmful to the ecological environment. Chemotactic degrading bacteria can perceive the concentration gradient of non-aqueous phase liquid (NAPL) pollutants in the groundwater environment, and enrich and proliferate around the pollutants, thus achieving a more efficient and thorough remediation effect. However, the existing theoretical models are relatively simple. The physical fields of oil–water two-phase flow and oil-phase solute convection and diffusion in water are not coupled, which further restricts the accuracy of studies on bacterial chemotaxis to NAPL. In this study, geometric models based on the actual microfluidic experimental study were constructed. Based on the phase field model, diffusion convection equation and chemotaxis velocity equation, the effects of heterogeneity of porous media, wall wettability and groundwater flow rate on the residual oil and the concentration distribution of chemotaxis bacteria were studied. Under all of the simulation conditions, the residual oil in the high permeable area was significantly lower than that in the low permeable area, and the wall hydrophilicity enhanced the water flooding effect. Chemotactic bacteria could react to the concentration gradient of pollutants dissolved into water in the oil phase, and enrich near the oil–water interface with high concentration of NAPL, and the density of chemotactic bacteria at the oil–water interface can be up to 1.8–2 times higher than that in the water phase at flow rates from 1.13 to 6.78 m/d.

An amount of oil remains in oil reservoirs even at the high water-cut stage of produced liquid from oil wells. To reveal the mechanism of displacement rates to affect the remaining oil in pore scales, a two-dimensional (2D) glass etching pore network model and real-time visual system were set up to observe the characteristics of oil distribution from water flooding and study the influence of displacement rates on oil recovery. It was found that the geometry of remaining oil in the pore network is diverse and dynamically changed at the high water-cut stage. Three geometric representative parameters were defined for the classification of five types of remaining oil (contiguous, branching, film, dropwise, bar columnar type), and controlling mechanisms for each type of remaining oil were analyzed. The experimental results show that the remaining oil saturation decreases from 21.2% to 6.5% when water injection rates increase from 0.05 to 0.5 mL/min. The increase in displacement rate improves the displacement efficiency of four types of remaining oil in the range of 55.00% to 93.67% except for dropwise type. The experimental data also indicate that the reduction in continuous residual oil and branched residual oil mainly contributes to the improvement of oil recovery of the whole network model. With the increase in displacement rate (from 0.05 to 0.1, 0.2, 0.3, 0.4, and 0.5 mL/min), the areas of five types of representative local residual oil reduce step by step. This research validates that the increase in water flooding rate in porous media leads to reduction in oil saturation, and it will improve oil recovery in oil reservoirs by enhancing water injection rates.

Combined with the characteristics of well pattern with high density and abundant dynamic and static data, the application of well-seismic technology in tapping the potential of remaining oil can improve the exploitation level of remaining oil. Through fine structural interpretation and hierarchical method, the practical application of well-seismic combination technology is discussed. Well-seismic combination depicts sedimentary facies, analyzes sand body characteristics, uses fine digital reservoir simulation to analyze remaining oil distribution characteristics, and studies the tapping process of different types of remaining oil, providing technical support for the next development adjustment and scheme optimization.

Lipid biomarkers play an important role in defining oil-source rock correlations. A fundamental assumption is that composition (or ratios) of biomarkers in oil is not significantly different from that in bitumen in the source rock. In order to compare the geochemical characteristics of expelled oil and residual oil, a Permian Tasmanite oil shale was used for an artificial maturation experiment to simulate the oil generation period. The results show that the Tasmanite oil shale generated high amounts of hydrocarbons (731 mg HC/g TOC) at low maturation temperatures (340 °C). The hydrocarbon (HC) group compositions are different between the expelled oil (with more aromatic HC and saturated HC) and the residual oil (with more resin fraction and asphaltene). The Pr/Ph ratio (up to 4.01) of the expelled hydrocarbons was much higher than that in residual oil (

There has been a great demand for flame stability particularly in low-grade residual oil-fired burners. In order to improve the performance of the residual oil burner, it is required to obtain the stable ignition by the swirler devices which create recirculating combustion gas and rotating fuel spray flows. In the present study, a numerical simulation was made on the flow behaviors of air circulation and droplet streamlines for two types of swirlers with different angles of guide vane. A stereo PIV measurement was also made on the velocity distribution of spray droplets. One type of the swirlers is a former type called “Bent plate swirler” with a constant bending angle of the guide vanes. The air after the guide vane expands to the outer circumferencial direction by centrifugal force and the swirling state abruptly declines. Another is a newly developed type “Wing-curved swirler” in which the bending angle of the guide vane becomes deeper from the center to the outer direction. The air flow maintains the swirling force and the recirculation flow is wider than the former “Bent plate swirler”. The Wing-curved swirler with a high swirl force, a swirl number of 2 or more, not only increases the swirl of the sprayed droplet but also lengthens its trajectories. The flame stability was improved by the burner equipped with the developed Wing-curved swirler. The decrease in dust concentration was demonstrated through the residual oil combustion test of the 10 MW actual burner.

In recent years, as the polymer drive of the main class I oil reservoir has been transferred to the subsequent water drive development, the class II oil reservoir has gradually become the main target of the three times oil recovery development, compared with the class I oil reservoir, the class II oil reservoir has the characteristics of relatively poor oil reservoir development and strong non-homogeneity. With the effect of the second-class oil layer successively, the fracturing target is mainly the second-class oil layer, but the fracturing effect becomes worse year by year, and it is difficult to produce in the next step. Therefore, it is important to optimize well selection for fracturing. In this paper, we analyze the effect of fracturing wells in Class II reservoirs in recent years and summarize the factors affecting the effect of fracturing in Class II reservoirs and the practices to ensure the effect of fracturing in Class II reservoirs, so as to provide a reference basis for the selection of wells for Class II fracturing in the future, which is of certain significance.

Environmentally friendly multipurpose grease formulation has been synthesized by using Jatropha vegetable residual oil with lithium soap and multifunctional additive. The thus obtained formulation was evaluated for its tribological performance on a four-ball tribo-tester. The anti-friction and anti-wear performance characteristics were evaluated using standard test methods. The biodegradability and toxicity of the base oil was assessed. The results indicate that the synthesized residual oil grease formulation shows superior tribological performance when compared to the commercial grease. On the basis of physico-chemical characterization and tribological performance the vegetable residual oil was found to have good potential for use as biodegradable multipurpose lubricating grease. In addition, the base oils are biodegradable and non toxic.

The production of palm oil requires a large amount of water, which subsequently turns into wastewater known as palm oil mill effluent (POME). Because of its high organic content, there has been debate over how to utilize POME for oil recovery. POME is usually mainly comprised of water (95 to 96%), total solids (4 to 5%), suspended solids (2 to 4%), and oil (0.6 to 0.7%). The lignocellulosic particles in POME are highly oleophilic and capable of absorbing oil. Therefore, the objective of this study was to understand the presence of residual oil and try to relate with the oil loss in POME and to identify the solid particles in POME and their correlations. Microscopic observations showed that most of the oil droplets available in POME were less than 100 µm in size. If given the opportunity to settle, the highest quantity of oil droplets and solid particles was in the bottom layer, followed by the middle layer, and lastly the upper layer. In cases where the contact angle of water was less than 45° on POME solids, the absorption rate was 0.11 ± 0.03 µL/s and 0.09 ± 0.01 µL/s, respectively. This study concluded that the oil losses in POME were partly due to the absorption of oil by the fibers.

Study on the residual oil distribution regularity is the important thing during the middle and later stage of the oilfield. With understanding and development of oilfield, the research methods of remaining oil are varied. Well block A is a low permeability oilfield and complex relationship between injection wells and production wells. The well pattern has low control of sand body. Based on the characteristics and the geological and dynamic data, technology of integrated 3-D geological modeling with reservoir numerical simulation is ensured to study the residual oil. Finally, deposition facies and flowing units are studied to analyze the residual oil distribution regularity. As a result, the types of residual oil were confirmed and the basis for the following development adjustment of the well block is provided.

The current importance of the paper is determined by the vital necessity that research and practical efforts should be now focused on studying and controlling the oilfield «life», based on conceptually new ideas and methods in petroleum geology. The aim of the article. To outline new trends and approaches in the development of petroleum geology. To substantiate the use of rehabilitation cycles in the process of developing an oilfield, and especially at its active (forced) stage. To define the perturbation threshold for state equilibrium of a fluid-saturated system. To propose a method for simulating dynamics of a hydrocarbon deposit. Methods used in the study. The author uses a wide range of methodic approaches and techniques, including his own well studies (drill samples, geophysical well logging data, pressure recovery curve, etc.) as well as long-term observations and generalizations of primary sources and materials on a great number of petroleum provinces in the world and especially in West Siberia. Results. The use of rehabilitation cycles in the process of developing an oilfield is substantiated. An empirical estimation is given of the value of critical perturbation for state equilibrium of a fluid-saturated system in the process of developing an oilfield, equal to formation depression of 5-8 MPa. A method for simulating oilfield dynamics is suggested and the use of an evolutionary equation [dp/dt=Z (p, a, t)] is justified. A method is proposed to create or renew highly-productive foci at an oilfield through technogenic initiation of an accelerated metasomatic dolomitisation in carbonate reservoirs. Innovative conceptions and approaches are suggested for the further development of petroleum science. The author's opinion is that at present efforts should be focused on the efficient well-targeted development of the active oilfields in order to provide for the production of the residual (hard-to-extract) oil in a soft, sparing and non-damaging way (Improved Oil Recovery) as well as on discovering new hydrocarbon accumulations, including secondary ones, throughout the whole stratigraphic section, with all depth horizons and various rock-fluid associations, in regions where a well-developed diversified infrastructure is already available. The use of rehabilitation cycles will make it possible to restore the energy potential of the stratum and filtration properties of the rock. In the long run, it will provide for an increased longevity of the object and higher final oil recovery. The urgent demand for constant real-time monitoring of the current changes inside the fluid-saturated stratum makes it extremely desirable to create research-and-development polygons in various petroleum regions.

The current importance of the paper is determined by the vital necessity that research and practical efforts should be now focused on studying and controlling the oilfield «life», based on conceptually new ideas and methods in petroleum geology. The aim of the article. To outline new trends and approaches in the development of petroleum geology. To substantiate the use of rehabilitation cycles in the process of developing an oilfield, and especially at its active (forced) stage. To define the perturbation threshold for state equilibrium of a fluid-saturated system. To propose a method for simulating dynamics of a hydrocarbon deposit. Methods used in the study. The author uses a wide range of methodic approaches and techniques, including his own well studies (drill samples, geophysical well logging data, pressure recovery curve, etc.) as well as long-term observations and generalizations of primary sources and materials on a great number of petroleum provinces in the world and especially in West Siberia. Results. The use of rehabilitation cycles in the process of developing an oilfield is substantiated. An empirical estimation is given of the value of critical perturbation for state equilibrium of a fluid-saturated system in the process of developing an oilfield, equal to formation depression of 5-8 MPa. A method for simulating oilfield dynamics is suggested and the use of an evolutionary equation [dp/dt=Z (p, a, t)] is justified. A method is proposed to create or renew highly-productive foci at an oilfield through technogenic initiation of an accelerated metasomatic dolomitisation in carbonate reservoirs. Innovative conceptions and approaches are suggested for the further development of petroleum science. The author's opinion is that at present efforts should be focused on the efficient well-targeted development of the active oilfields in order to provide for the production of the residual (hard-to-extract) oil in a soft, sparing and non-damaging way (Improved Oil Recovery) as well as on discovering new hydrocarbon accumulations, including secondary ones, throughout the whole stratigraphic section, with all depth horizons and various rock-fluid associations, in regions where a well-developed diversified infrastructure is already available. The use of rehabilitation cycles will make it possible to restore the energy potential of the stratum and filtration properties of the rock. In the long run, it will provide for an increased longevity of the object and higher final oil recovery. The urgent demand for constant real-time monitoring of the current changes inside the fluid-saturated stratum makes it extremely desirable to create research-and-development polygons in various petroleum regions.

This research which is based on experimental work, devoted to study the improvement and stabilization of dune sands in order to create strong layer and stabilize slope and floor construction of sewage Lagoons. Materials used stabilizing these soils are residual oil from the refinery. To confirm the effectiveness of the use of residual oil to improve the mechanical properties of the sand, various samples with different percentages were tested. In besides, the geotechnical and environmental tests were done. Results demonstrate that samples made with 5% oil have highest shear and unconfined compaction strength. It revealed that in compare with natural samples, cohesion and loading capacity highly increased and permeability decrease well. Percentage of fine aggregate, minerals and durability of oil in soil material were also investigated. Finally, effects of sewage on the samples were analyzed, and performance the oils were evaluated in order to use in lagoons.

Currently, semi-refined and refined vegetable oils are used as a feedstock in biodiesel production. However, due to competition with conventional fossil fuel, economic reasons, shortage supply of food and its social impact on the global scale has somewhat slowed the development of biodiesel industry. Studies have been conducted to recover oil from mill palm oil operation especially from the spent bleaching earth. Hence, the study was to investigate the potential recovery of oil from spent bleaching earth to be used as a feedstock for biodiesel production. The effect of different types of catalysts (sodium hydroxide alkali and sulfuric acid catalysts) on biodiesel yield was studied. In addition, the effect of volume addition of methanol to the weight of spent bleaching earth on the product yield was also studied. Furthermore, the effect of ratio of hexane to methanol was also carried out to determine its product yield. The studies were carried out in an in-situ biodiesel reactor system and the biodiesel product was analyzed using gas chromatography mass spectrometry. Result shows that the use of alkali catalyst produced the highest yield of biodiesel and the most optimum biodiesel yield was obtained when the methanol to spent bleaching earth ratio was 3.2:1 (gram of methanol: gram of SBE) and hexane to methanol ratio of 0.6:1 (volume of hexane: volume of methanol). © 2011 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0)