Search Results (229)

Against the backdrop of global energy transition and strict environmental regulations, supercritical carbon dioxide (scCO₂) fracturing and oil displacement technologies have emerged as pivotal green approaches in shale gas exploitation, offering the dual advantages of zero water consumption and carbon sequestration. However, the inherent low viscosity of scCO₂ severely restricts its sand-carrying capacity, fracture propagation efficiency, and oil recovery rate, necessitating the urgent development of high-performance thickeners. The current research on scCO₂ thickeners faces a critical trade-off: traditional fluorinated polymers exhibit excellent philicity CO₂, but suffer from high costs and environmental hazards, while non-fluorinated systems often struggle to balance solubility and thickening performance. The development of new thickeners primarily involves two directions. On one hand, efforts focus on modifying non-fluorinated polymers, driven by environmental protection needs—traditional fluorinated thickeners may cause environmental pollution, and improving non-fluorinated polymers can maintain good thickening performance while reducing environmental impacts. On the other hand, there is a commitment to developing non-noble metal-catalyzed siloxane modification and synthesis processes, aiming to enhance the technical and economic feasibility of scCO₂ thickeners. Compared with noble metal catalysts like platinum, non-noble metal catalysts can reduce production costs, making the synthesis process more economically viable for large-scale industrial applications. These studies are crucial for promoting the practical application of scCO₂ technology in unconventional oil and gas development, including improving fracturing efficiency and oil displacement efficiency, and providing new technical support for the sustainable development of the energy industry. This study innovatively designed an amphiphilic modified amino silicone oil polymer (MA-co-MPEGA-AS) by combining maleic anhydride (MA), methoxy polyethylene glycol acrylate (MPEGA), and amino silicone oil (AS) through a molecular bridge strategy. The synthesis process involved three key steps: radical polymerization of MA and MPEGA, amidation with AS, and in situ network formation. Fourier transform infrared spectroscopy (FT-IR) confirmed the successful introduction of ether-based CO₂-philic groups. Rheological tests conducted under scCO₂ conditions demonstrated a 114-fold increase in viscosity for MA-co-MPEGA-AS. Mechanistic studies revealed that the ether oxygen atoms (Lewis base) in MPEGA formed dipole–quadrupole interactions with CO₂ (Lewis acid), enhancing solubility by 47%. Simultaneously, the self-assembly of siloxane chains into a three-dimensional network suppressed interlayer sliding in scCO₂ and maintained over 90% viscosity retention at 80 °C. This fluorine-free design eliminates the need for platinum-based catalysts and reduces production costs compared to fluorinated polymers. The hierarchical interactions (coordination bonds and hydrogen bonds) within the system provide a novel synthetic paradigm for scCO₂ thickeners. This research lays the foundation for green CO₂-based energy extraction technologies. Full article

Capturing CO₂ emitted by coal chemical enterprises and injecting it into oil reservoirs not only effectively improves the recovery rate and development efficiency of tight oil reservoirs in the Ordos Basin but also addresses the carbon emission problem constraining the development of the region. Since initiating field experiments in 2012, the Ordos Basin has become a significant base for CCUS (Carbon capture, Utilization, and Storage) technology application and demonstration in China. However, over the years, projects have primarily focused on enhancing the recovery rate of CO₂ flooding, while issues such as potential reservoir damage and its extent have received insufficient attention. This oversight hinder the long-term development and promotion of CO₂ flooding technology in the region. Experimental results were comprehensively analyzed using techniques including nuclear magnetic resonance (NMR), X-ray diffraction (XRD), scanning electron microscopy (SEM), inductively coupled plasma (ICP), and ion chromography (IG). The findings indicate that under current reservoir temperature and pressure conditions, significant asphaltene deposition and calcium carbonate precipitation do not occur during CO₂ flooding. The reservoir’s characteristics-high feldspar content, low carbon mineral content, and low clay mineral content determine that the primary mechanism affecting physical properties under CO₂ flooding in the Chang 4 + 5 tight sandstone reservoir is not, as traditional understand, carbon mineral dissolution or primary clay mineral expansion and migration. Instead, feldspar corrosion and secondary particles migration are the fundamental reasons for the changes in reservoir properties. As permeability increases, micro pore blockage decreases, and the damaging effect of CO₂ flooding on reservoir permeability diminishes. Permeability and micro pore structure are therefore significant factors determining the damage degree of CO₂ flooding inflicts on tight reservoirs. In addition, temperature and pressure have a significant impact on the extent of reservoir damage caused by CO₂ flooding in the study region. At a given reservoir temperature, increasing CO₂ injection pressure can mitigate reservoir damage. It is recommended to avoid conducting CO₂ flooding projects in reservoirs with severe pressure attenuation, low permeability, and narrow pore throats as much as possible to prevent serious damage to the reservoir. At the same time, the production pressure difference should be reasonably controlled during the production process to reduce the risk and degree of calcium carbonate precipitation near oil production wells. Full article

The increasing incidence of oil contamination in many aquatic ecosystems, particularly in oil-rich regions such as Qatar, poses significant threats to marine life and human activities. Our study addresses the critical need for effective and eco-friendly oil-water separation techniques, focusing on developing graphene and chitosan-based three-dimensional (3D) polymeric sponges. These materials have demonstrated potential due to their high porosity and surface area, which can be enhanced through surface treatment to improve hydrophobicity and oleophilicity. This study introduces a new technique dependent on the optimization of the graphene oxide (GO) concentration within the composite sponge to achieve a superior oil uptake capacity (51.4 g oil/g sponge at 3% GO), and the detailed characterization of the material’s performance in separating heavy oil-water emulsions. Our study seeks to answer key questions regarding the performance of these modified sponges and their scalability for industrial applications. This research directly aligns with Qatar’s environmental goals and develops sustainable oil-water separation technologies. It addresses the pressing challenges of oil spills, ultimately contributing to improved marine ecosystem protection and efficient resource recovery. Full article

Distribution transformers serve as critical nodes in smart grids, and management of their recycling plays a vital role in the full life-cycle management for electrical equipment. However, the traditional manual dismantling methods often exhibit a low metal recovery efficiency and high levels of hazardous substance residue. To facilitate green, cost-effective, and fine-grained recycling of distribution transformers, this study proposes a fine-grained dismantling decision-making system based on a knowledge graph subgraph comparison and multimodal fusion perception. First, a standardized dismantling process is designed to achieve refined transformer decomposition. Second, a comprehensive set of multi-dimensional evaluation metrics is established to assess the effectiveness of various recycling strategies for different transformers. Finally, through the integration of multimodal perception with knowledge graph technology, the system achieves automated sequencing of the dismantling operations. The experimental results demonstrate that the proposed method attains 99% accuracy in identifying recyclable transformers and 97% accuracy in auction-based pricing. The residual oil rate in dismantled transformers is reduced to below 1%, while the metal recovery efficiency increases by 40%. Furthermore, the environmental sustainability and economic value are improved by 23% and 40%, respectively. This approach significantly enhances the recycling value and environmental safety of distribution transformers, providing effective technical support for smart grid development and environmental protection. Full article

Unconventional hydrocarbon reservoirs with low matrix permeability (<0.3 mD), high temperatures, and sour conditions present significant challenges for stimulation and production enhancement. This study examines field trials for a large oil and gas operator in the UAE, focusing on tight carbonate deposits with reservoir temperatures above 93 °C and high sour gas content. A novel multi-stage chemical stimulation workflow was created, beginning with a pre-flush phase that alters rock wettability and reduces interfacial tension at the micro-scale. This was followed by a second phase that increased near-wellbore permeability and ensured proper acid placement. The treatment’s core used a thermally stable, corrosion-resistant retarded acid system designed to slow reaction rates, allow deeper acid penetration, and build prolonged conductive wormholes. Simulations revealed considerable acid penetration of the formation beyond the near-wellbore zone. The post-treatment field data showed a tenfold improvement in injectivity, which corresponded closely to the acid penetration profiles predicted by modeling. Furthermore, oil production demonstrated sustained, high oil production of 515 bpd on average for several months after the treatment, in contrast to the previously unstable and low-rate production. Finally, the findings support a reproducible and technologically advanced stimulation technique for boosting recovery in ultra-tight carbonate reservoirs using the acid retardation effect where traditional stimulation fails. Full article

Two-phase expansion processes have emerged as a promising technology for enhancing energy efficiency in power generation, refrigeration, waste heat recovery systems (for example, partially evaporated organic Rankine cycle, organic flash cycle, and trilateral flash cycle), oil and gas, and other applications. However, despite their potential, widespread adoption is hindered by inherent challenges, particularly energy losses that reduce operational efficiency. This review systematically evaluates the current state of two-phase expansion technologies, focusing on the root causes, impacts, and mitigation strategies for expansion losses. This work used Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). Using the PRISMA framework, 52 relevant publications were identified from Scopus and Web of Science to conduct the systematic review. A preliminary co-occurrence analysis of keywords was also conducted using VOSviewer version 1.6.20. Three clusters were observed in this co-occurrence analysis. However, the results may not be significant. Therefore, the extended work was done through a comprehensive analysis of experimental and simulation studies from the literature. This study identifies critical loss mechanisms in key components of two-phase expanders, such as the nozzle, diffuser, rotor, working chamber, and vaneless space. Also, losses arising from wetness, such as droplet formation, interfacial friction, and non-equilibrium phase transitions, are examined. These phenomena degrade performance by disrupting flow stability, increasing entropy generation, and causing mechanical erosion. Several losses in the turbine and volumetric expanders operating in two-phase conditions are reported. Ejectors, throttling valves, and flashing flow systems that exhibit similar challenges of losses are also discussed. This review discusses the mitigation and the strategy to minimize the two-phase expansion losses. The geometry of the inlet of the two-phase expanders plays an important role, which also needs improvement to minimize losses. The review highlights recent advancements in addressing these challenges and shows optimization opportunities for further research. Full article

Micro-nano bubbles (MNBs) are tiny bubbles with diameters ranging from 200 nm to 30 µm. They possess unique physicochemical properties such as a large specific surface area, slow rising velocity, high gas dissolution rate, high mass transfer efficiency, and strong interfacial zeta potential. These properties endow MNBs with great potential in various fields, including water treatment, enhanced oil recovery, medical and health care, and agriculture. This paper systematically reviews the physicochemical properties, generation methods, and applications of micro-nano bubbles. The main production methods include the mechanical stirring, pressurized dissolved gas release, ultrasonic cavitation, venturi injection, electrolysis, etc. The principles, advantages and disadvantages, and optimization strategies of these methods are comprehensively analyzed. In terms of applications, the mechanisms and typical cases of MNBs in enhanced oil recovery, water treatment, mineral flotation, medical drug delivery, and crop yield enhancement are thoroughly discussed. Extensive research has shown that MNB technology is highly efficient, energy-saving, and environmentally friendly. However, improving bubble stability, generation efficiency, and large-scale application remain key directions for future research. Full article

The massive heavy oil reserves in the Athabasca region of northern Alberta depend on steam-assisted gravity drainage (SAGD) for their economic exploitation. Even though SAGD has been successful in highly viscous oil recovery, it is still a costly technology because of the large energy input requirement. Large water and natural gas quantities needed for steam generation imply sizable greenhouse gas (GHG) emissions and extensive post-production water treatment. Several methods to make SAGD more energy-efficient and environmentally sustainable have been attempted. Their main goal is to reduce steam consumption whilst maintaining favourable oil production rates and ultimate oil recovery. Oil saturation within the steam chamber plays a critical role in determining both the economic viability and resource efficiency of SAGD operations. However, accurately quantifying the residual oil saturation left behind by SAGD remains a challenge. In this experimental research, sand pack Expanding Solvent SAGD (ES-SAGD) coinjection experiments are reported in which Pentane -C₅H₁₂, and Hexane -C₆H₁₄ were utilised as an additive to steam to produce Long Lake bitumen. Each solvent is assessed at three different constant concentrations through time using experiments simulating SAGD to quantify their impact. The benefits of single-component solvent coinjection gradually diminish as the SAGD process approaches its later stages. ES-SAGD pentane coinjection offers a smaller improvement in recovery factor (RF) (4% approx.) compared to hexane (8% approx.). Between these two single-component solvents, 15 vol% hexane offered the fastest recovery. The obtained data in this research provided compelling evidence that the coinjection of solvent under carefully controlled operating conditions, reduced overall steam requirement, energy consumption, and residual oil saturation allowing proper adjustment of oil and water relative permeability curve endpoints for field pilot reservoir simulations. Full article

Oilseed cakes, by-products of oil extraction, represent an underutilized resource with significant potential for sustainable food and pharmaceutical applications. This comprehensive review examines the valorization strategies for oilseed cakes, focusing on their rich protein (up to 56%) and fiber (up to 66%) content. We analyze both conventional and innovative extraction methods, highlighting the advantages of ultrasound-assisted (96.64% phenolic compound yield), enzymatic (82–83% protein recovery), and subcritical water extraction techniques in improving efficiency while reducing environmental impact. This review demonstrates diverse applications of oilseed cake components from gluten-free bakery products and plant-based meat alternatives to advanced nanoencapsulation systems for bioactive compounds. Each major oilseed type (soybean, rapeseed, sunflower and flaxseed) exhibits unique nutritional and functional properties that can be optimized through appropriate processing. Despite technological advances, challenges remain in scaling extraction methods and balancing yield with functionality. This paper identifies key research directions, including the development of integrated biorefinery approaches and the further exploration of health-promoting peptides and fibers. By addressing these challenges, oilseed cakes can play a crucial role in sustainable food systems and the circular economy, transforming agricultural by-products into high-value ingredients while reducing waste. Full article

Sewage sludge, as a by-product of wastewater treatment, poses severe environmental challenges due to its high moisture, ash, and heavy metal content. Thermochemical conversion technologies, including pyrolysis and gasification, offer promising pathways for transforming sludge into valuable products such as bio-oil, biochar, and syngas. This paper systematically reviews recent advancements in pyrolysis and gasification, focusing on process optimization and catalyst development to enhance product quality and energy recovery. In pyrolysis, factors such as temperature, residence time, and heating rate significantly influence product yields and properties, while catalytic and co-pyrolysis approaches further improve product structure and reduce environmental risks. In gasification, parameters like the equivalence ratio, steam-to-sludge ratio, and catalyst application are key to enhancing syngas yield and quality, with biomass co-gasification offering additional benefits. Despite substantial progress, commercialization remains challenged by high operational costs, catalyst durability, and environmental impacts. Future research should emphasize improving sludge pretreatment, optimizing thermochemical processes, developing efficient and cost-effective catalysts, and addressing critical issues such as bio-oil quality, tar management, and syngas purification to promote the industrial application of these technologies. Full article

This study explores the potential of lysine (Lys) and tilapia myofibrillar protein (MP) composite particles in the formulation of highly inwardly directed emulsions (HIPEs). Infrared spectroscopy, potentiometric analysis, and molecular docking studies revealed that the interaction between Lys and MP is primarily governed by hydrogen bonding and electrostatic forces. The incorporation of Lys significantly influenced the particle size, secondary and tertiary structures, solubility, and turbidity of MP. Lys-MP-stabilized HIPEs can form highly stable denser self-supporting gel network structures. Rheological analysis of HIPEs stabilized by MP showed a low energy storage modulus (G’ 110.66 Pa) and water–oil separation, therefore preventing 3D printing. However, HIPEs stabilized by Lys (especially 1.5 wt%) significantly improved the energy storage modulus (G’ 1002.10 Pa), increased viscoelasticity and thixotropic recovery, and reduced droplet size (10.84 μm), facilitating the use of HIPE inks for 3D printing. Furthermore, HIPEs stabilized with 1.5 wt% Lys-MP demonstrated superior print accuracy (91.36%), resolution, and clarity in 3D printing applications. Overall, these findings offer a promising strategy for developing Lys-MP composite particle-stabilized HIPEs tailored for advanced 3D printing technologies. Full article

The scaling up of carbon capture, utilization, and storage (CCUS) deployment is constrained by multiple factors, including technological immaturity, high capital expenditures, and extended investment return periods. The existing research on CCUS investment decisions predominantly centers on coal-fired power plants, with the utilization pathways placing a primary emphasis on storage or enhanced oil recovery (EOR). There is limited research available regarding the chemical utilization of carbon dioxide (CO₂). This study develops an options-based analytical model, employing geometric Brownian motion to characterize carbon and oil price uncertainties while incorporating the learning curve effect in carbon capture infrastructure costs. Additionally, revenues from chemical utilization and EOR are integrated into the return model. A case study is conducted on a process producing 100,000 tons of methanol annually via CO₂ hydrogenation. Based on numerical simulations, we determine the optimal investment conditions for the “CO₂-to-methanol + EOR” collaborative scheme. Parameter sensitivity analyses further evaluate how key variables—carbon pricing, oil market dynamics, targeted subsidies, and the cost of renewable electricity—influence investment timing and feasibility. The results reveal that the following: (1) Carbon pricing plays a pivotal role in influencing investment decisions related to CCUS. A stable and sufficiently high carbon price improves the economic feasibility of CCUS projects. When the initial carbon price reaches 125 CNY/t or higher, refining–chemical integrated plants are incentivized to make immediate investments. (2) Increases in oil prices also encourage CCUS investment decisions by refining–chemical integrated plants, but the effect is weaker than that of carbon prices. The model reveals that when oil prices exceed USD 134 per barrel, the investment trigger is activated, leading to earlier project implementation. (3) EOR subsidy and the initial equipment investment subsidy can promote investment and bring forward the expected exercise time of the option. Immediate investment conditions will be triggered when EOR subsidy reaches CNY 75 per barrel or more, or the subsidy coefficient reaches 0.2 or higher. (4) The levelized cost of electricity (LCOE) from photovoltaic sources is identified as a key determinant of hydrogen production economics. A sustained decline in LCOE—from CNY 0.30/kWh to 0.22/kWh, and further to 0.12/kWh or below—significantly advances the optimal investment window. When LCOE reaches CNY 0.12/kWh, the project achieves economic viability, enabling investment potentially as early as 2025. This study provides guidance and reference cases for CCUS investment decisions integrating EOR and chemical utilization in China’s refining–chemical integrated plants. Full article

Research on nanomaterials has opened up new opportunities for enhancing oil recovery. This paper reviews the mechanisms of nanomaterials for enhancing oil recovery, including reducing oil–water interfacial tension, regulating rock wettability, and decreasing crude oil viscosity, with a focus on the expansion of the oil-displacement mechanism of nano-silica. Nanofluids form interfacial nanolayers that diminish tension while altering surface wettability to promote oil stripping. Their structural disjoining pressure creates wedge-shaped films at oil–water–solid interfaces, driving droplet detachment. The synergistic “roll-up” and “diffusion” mechanisms improve oil mobility through capillary regulation and interfacial disturbance. These findings offer critical insights for optimizing nanomaterial applications in oil displacement systems, advancing fundamental research and technological development for enhanced recovery processes. Full article

Low permeability oil reservoirs hold an important position in the global oil resource reserves. They boast abundant reserves and serve as one of the crucial sources for crude oil reserve replacement in China and even the world. The mechanisms for improving the oil recovery rate in high-oil-bearing reservoirs include improving fluid properties, enhancing displacement efficiency, etc. However, their development is quite challenging, requiring continuous exploration and innovation in development technologies. This study addresses the unclear distribution patterns of microbial communities and the incomplete understanding of microbial enhanced oil recovery (MEOR) mechanisms in low permeability reservoirs. Utilizing high-throughput genomics and functional gene analysis techniques, combined with laboratory and field data, the study investigates the distribution and growth patterns of microbial communities in a low permeability reservoir, exemplified by the S169 block. Additionally, the potential of MEOR to enhance oil recovery and its underlying mechanisms are explored. The results indicate that microbial communities in low permeability reservoirs exhibit strong heterogeneity, with their distribution closely correlated to geological factors such as reservoir permeability and porosity. The diversity of microbial communities is positively correlated with oil recovery efficiency, and highly active microbial populations promote the production of metabolites that enhance oil recovery. The metabolic products of microorganisms help reduce the interfacial tension between oil and water, improve the fluidity of oil, and enhance the recovery rate. In addition, the structural changes in microbial communities are closely related to factors such as the permeability and porosity of reservoirs. This study provides a theoretical basis for the optimization of microbial enhanced oil recovery (MEOR) technology. Full article

During the waterflooding recovery process, water is injected into the hydrocarbon reservoirs and displaces a portion of the oil and gas, thereby improving oil and gas recovery rates and extending the production life of the reservoir. The macro benefits of waterflooding technology are widely recognized; however, the micro-scale effects of water on the reservoir’s pore structure and fluid distribution during the injection process remain underexplored. Therefore, this study aims to analyze the micro-distribution characteristics of fluids in the reservoir during the oil–water displacement process. To further investigate the micro-mechanisms of waterflooding recovery and the factors influencing recovery efficiency, the study focuses on the impact of permeability, pressure gradient, injection volume, and reverse displacement on oil recovery efficiency. A combined qualitative and quantitative analysis approach was employed, using techniques such as nuclear magnetic resonance (NMR), CT scanning, and fluid distribution tomography to comprehensively analyze the fluid evolution patterns within the reservoir. The results show the following: (1) The movable fluids in the oilfield are primarily distributed within pores ranging from 0.1 to 40 μm; the remaining oil is mainly distributed within pores of 0.1 to 10 μm, accounting for over 85% of the total distribution, and these pores serve as the main space for extracting remaining oil in later stages. (2) Increasing the injection volume significantly improves the oil recovery efficiency in pores ranging from 0.1 to 10 μm. Increasing the displacement pressure gradient effectively reduces remaining oil in pores of 0.1 to 5 μm. However, for reservoirs with permeability greater than 10 mD, once the injection volume exceeds 1 PV or the displacement pressure gradient exceeds 1.8 MPa/m, the increase in oil recovery efficiency becomes marginal. (3) With increasing water injection multiples, the oil displacement efficiency of cores with varying permeability levels shows an overall upward trend. However, the extent of improvement varies significantly, with low-permeability cores exhibiting a markedly greater enhancement in displacement efficiency compared to high-permeability cores. (4) Reverse displacement can reduce the remaining oil in pores ranging from 0.1 to 10 μm, and the increase in oil recovery efficiency is more significant in cores with lower permeability than in those with higher permeability. Therefore, increased production cannot solely rely on improving the production pressure differential to develop remaining oil. Full article