Energy & Fuels最新文献

This study investigates the distribution and genesis of heavy oil in the Chepaizi Uplift by analyzing various aspects, including physical properties (density, viscosity, wax content, sulfur content, water content, and total acid number), molecular and bulk characteristics, hydrogeochemical data of formation water (total dissolved solids, pH values, and hydrochemical types), geothermal data, and microthermometry of fluid inclusions. The research identifies biodegradation as the dominant factor increasing oil viscosity with oxidation exacerbating this process. Conversely, water washing and diffusion have minimal impact on the oil viscosity increase, and the formation of heavy oil from low maturity source rocks is unlikely. Regional variations in viscosity increase factors are observed, with Eastern Chepaizi showing higher biodegradation due to lower mineralization, poor formation water types, and favorable temperatures and pH conditions compared to Western Chepaizi and the Hongche Fault Belt. Fluid inclusion microthermometry and biomarker characteristics indicated that the lower strata (C-J) of the Eastern Chepaizi experienced two hydrocarbon charging stages, corresponding to an early stage of heavy oil and a later stage of light oil charging, whereas Western Chepaizi had a single stage. The western region of Western Chepaizi and the central region of the Hongche Fault Belt are prime targets for light oil exploration. The hinge line of Chepaizi Uplift requires certain thermal recovery methods for extraction due to the high density and viscosity of crude oil. These zones reflect the varying degrees of secondary alteration processes that have affected crude oil in the study area. These findings hold significant guidance for future exploration and deployment of heavy oil resources in this region and serve as a reference for studying the genesis of heavy oil in other complex geological settings.

Capture and storage of CO₂ in underground geological formations has been identified as a sustainable solution for mitigating the effects of greenhouse gases. Combining this CO₂ sequestration with enhanced oil recovery (EOR) processes can reduce the economic risk of carbon capture and storage (CCS). Injecting CO₂ alternately with water (water alternating gas or WAG) is recognized as one of the most effective methods for increasing oil production and enhancing CO₂ sequestration. This study aims to optimize the CO₂ injection process into oil reservoirs using the WAG method, explicitly focusing on incorporating various carbon sequestration mechanisms. Due to the inherent complexities of the WAG injection process and the conflicts of interest between specific CO₂ sequestration mechanisms and cumulative oil production (COP), there is a need for a practical multiobjective optimization approach. In this study, based on the mechanisms of CO₂ trapping in the oil reservoir, three different objective functions representing the moles of CO₂ trapped in different phases within the reservoir, along with the COP objective function, were considered. Using reservoir simulation, 366 realizations were designed based on seven decision variables, and the four mentioned objective functions were calculated. Initial correlation analysis among the objective functions confirmed a conflict of interest between the COP objective function, the CO₂ trapped in oil (CTO) and water (CTW) phases, and conflicts between the trapping mechanisms. Multiple proxy models were trained using the created data set and two machine learning methods, XGBOOST, and neural networks. Ultimately, a neural network with an R² of 0.9886 for the training phase and 0.9562 for the test phase was selected as the validated proxy model. Optimizing solutions were evaluated by integrating the proxy model with three multiobjective optimization algorithms (NSGA-II, PESA-II, and MOPSO). Due to the conflict of interest among the objective functions, optimization was conducted using two different cost function settings, ensuring that all potential optimal solutions were identified. The results demonstrated that the shape of the Pareto front and the arrangement of the optimal solutions change when CO₂ trapping mechanisms are applied, compared to previous optimization approaches. The CO₂ sequestration objective function is significantly better optimized when these trapping mechanisms are included in the optimization process. Therefore, incorporating various CO₂ trapping mechanisms into the CO₂–WAG process optimization framework is essential to avoid overlooking potential solutions.

A novel solid amine adsorbent meso-PDVB@HBPE-x was prepared by impregnating and cross-linking the hyperbranched amine polymer (HBP-NH₂) in a mesoporous polydivinylbenzene (meso-PDVB) substrate with an open-cell structure. The optimum preparation conditions were investigated in detail, and the CO₂ adsorption performance of prepared adsorbents was conducted by a fixed bed dynamic adsorption system. It is suggested that beneficial from the low viscosity, the intramolecular cavity of HBP-NH₂, and the open-cell structure of meso-PDVB, the best adsorbent meso-PDVB@HBPE-8, which was slightly cross-linked with ethylene glycol diglycidyl ether (EGDE), exhibited a high CO₂ adsorption capacity of 5.64 mmol/g under 25 °C and wet conditions and quick adsorption kinetics (a high Q_b/Q_e ratio of 0.92). Compared with the low-molecular-weight amine tetraethylene pentaamine, HBP-NH₂ processes a higher molecular weight and is easily modified. Through cross-linking with EGDE, the N content and CO₂ adsorption capacity of meso-PDVB@HBPE-8 remained stable during 20 absorption (at 25 °C)–desorption (at 90 °C) cycles under wet conditions, showing great regeneration stability. The adsorbents showed great potential in CO₂/CH₄ separation, achieving a CH₄ productivity of 18.86 mmol/g from a 15 mL of CO₂/CH₄ (20:80, v:v) mixed gas. The strategy of synergistically designing the amine and substrate porous structures demonstrates its advantage in the practical application of CO₂ adsorption and separation.

Biomass and biomass wastes can be a source of renewable energy and fuels through valorization in thermochemical processes. Torrefaction is a thermal pretreatment often employed for upgrading raw biomass. In addition to providing the status of current techniques used to characterize raw and torrefied biomasses (in terms of their flowability and physicochemical, thermal, and bulk properties), we discuss current applications with these bulk solids. The limitations of current characterization methods are also discussed with a view to future scopes with advanced techniques, particularly related to physicochemical properties. This Review underscores a lack of systematic studies focused on the importance of comprehensive knowledge of raw and torrefied biomass properties to achieve better flowability, thereby contributing to more efficient and cost-effective industrial processes. Indeed, among the 1320 literature papers evaluated in this review, 647 characterized the chemical/thermal properties of raw and torrefied biomasses, while 254 considered physical/bulk properties, and only 11 assessed bulk solids’ flowability. The scarcity of studies on flowability suggests that this parameter has not been considered important by most researchers for the demonstration of process feasibility. However, characterizing bulk solids flow behavior is critical for the proper design of handling equipment and ensuring smooth plant operation, thus minimizing risks associated with unforeseen expenses and prolonged time for process troubleshooting and equipment retrofit. Moreover, even when the flowability was measured in the 11 papers, it was difficult to compare results between studies as measurement techniques were not the same, nor were the biomass type or torrefaction conditions. This highlights the need for future research on the flowability of raw and torrefied biomass, intending to obtain more sound and broad conclusions for the flow behavior of such heterogeneous materials, culminating in the development of standardized protocols to improve biomass handling and processing at an industrial scale. Besides, most of the studies available in the literature were based on small-bench torrefaction units, producing only a few grams of torrefied biomass. This is generally a limiting amount of material for complete assessment of flowability at different bulk conditions as well as to evaluate other important handling aspects at industrial scale, such as bulk solid segregation, quality of fluidization, and so on. In future works, we also suggest evaluating other heterogeneous feedstocks, such as municipal wastes or refuse-derived fuels, and performing a complete characterization for the bulk solids to facilitate technical decision-making in bioenergy and biofuels processes.