Hasil untuk "Petroleum refining. Petroleum products"

V. Siracusa, I. Blanco

In recent year, there has been increasing concern about the growing amount of plastic waste coming from daily life. Different kinds of synthetic plastics are currently used for an extensive range of needs, but in order to reduce the impact of petroleum-based plastics and material waste, considerable attention has been focused on “green” plastics. In this paper, we present a broad review on the advances in the research and development of bio-based polymers analogous to petroleum-derived ones. The main interest for the development of bio-based materials is the strong public concern about waste, pollution and carbon footprint. The sustainability of those polymers, for general and specific applications, is driven by the great progress in the processing technologies that refine biomass feedstocks in order to obtain bio-based monomers that are used as building blocks. At the same time, thanks to the industrial progress, it is possible to obtain more versatile and specific chemical structures in order to synthetize polymers with ad-hoc tailored properties and functionalities, with engineering applications that include packaging but also durable and electronic goods. In particular, three types of polymers were described in this review: Bio-polyethylene (Bio-PE), bio-polypropylene (Bio-PP) and Bio-poly(ethylene terephthalate) (Bio-PET). The recent advances in their development in terms of processing technologies, product development and applications, as well as their advantages and disadvantages, are reported.

Thomas Fiedler

We refine the combinatorial 1-cocycle $\mathbb{L}R_{reg}$ for regular isotopies of long knots to a 1-cocycle with values in the free $\mathbb{Z}[x,x^{-1}]$-module generated by regular isotopy classes of oriented tangles with exactly one signed ordinary double point. We use it to define the refined tangle equations for couples of knot diagrams, where the coefficients are now Laurent polynomials instead of integers. A solution of the tangle equations gives quantitative information about any knot isotopy which relates two given knot diagrams. If the tangle equations have no solution, then the diagrams represent different knots.

Sander Tonkens, Sosuke Kojima, Chenhao Liu et al.

Control Barrier Functions (CBFs) are a powerful tool for ensuring robotic safety, but designing or learning valid CBFs for complex systems is a significant challenge. While Hamilton-Jacobi Reachability provides a formal method for synthesizing safe value functions, it scales poorly and is typically performed offline, limiting its applicability in dynamic environments. This paper bridges the gap between offline synthesis and online adaptation. We introduce refineCBF for refining an approximate CBF - whether analytically derived, learned, or even unsafe - via warm-started HJ reachability. We then present its computationally efficient successor, HJ-Patch, which accelerates this process through localized updates. Both methods guarantee the recovery of a safe value function and can ensure monotonic safety improvements during adaptation. Our experiments validate our framework's primary contribution: in-the-loop, real-time adaptation, in simulation (with detailed value function analysis) and on physical hardware. Our experiments on ground vehicles and quadcopters show that our framework can successfully adapt to sudden environmental changes, such as new obstacles and unmodeled wind disturbances, providing a practical path toward deploying formally guaranteed safety in real-world settings.

Zhefei Gong, Shangke Lyu, Pengxiang Ding et al.

Imitation learning (IL) enables efficient skill acquisition from demonstrations but often struggles with long-horizon tasks and high-precision control due to compounding errors. Residual policy learning offers a promising, model-agnostic solution by refining a base policy through closed-loop corrections. However, existing approaches primarily focus on local corrections to the base policy, lacking a global understanding of state evolution, which limits robustness and generalization to unseen scenarios. To address this, we propose incorporating global dynamics modeling to guide residual policy updates. Specifically, we leverage Koopman operator theory to impose linear time-invariant structure in a learned latent space, enabling reliable state transitions and improved extrapolation for long-horizon prediction and unseen environments. We introduce KORR (Koopman-guided Online Residual Refinement), a simple yet effective framework that conditions residual corrections on Koopman-predicted latent states, enabling globally informed and stable action refinement. We evaluate KORR on long-horizon, fine-grained robotic furniture assembly tasks under various perturbations. Results demonstrate consistent gains in performance, robustness, and generalization over strong baselines. Our findings further highlight the potential of Koopman-based modeling to bridge modern learning methods with classical control theory.

WANG Zhouhua, ZHANG Hongyu, ZHANG Juan et al.

Gas-water relative permeability measurement is a common method to describe the flow process in gas reservoirs with water. However， the results of relative permeability measurements vary significantly between different test methods and types of cores. To deepen the understanding of the microscopic distribution characteristics of fluid and flow mechanism during the gas-water flow process， this paper took YB Gas Field in Sichuan Basin as the research object and used nuclear magnetic resonance （NMR） technology to quantitatively describe the microscopic distribution of the two phases before and after relative permeability test. The distribution results were explained based on the gas-water two-phase flow mechanism obtained by the previous researchers with the visualization model. The results showed that the displacement efficiencies of micron-scale （>1 μm） pores during the water displacing gas and gas displacing water are basically the same with the two test methods， but the displacement efficiency in submicron-scale （0.1–1 μm） and nanoscale （<0.1 μm） pores during water displacing gas is relatively higher. Moreover， the water in the submicron-scale and nanoscale pores is not mainly produced during the gas displacing water. For fractured and porous cores， the displacement efficiencies in micron-scale pores of fractured cores are relatively low， while the displacement efficiencies in submicron-scale and nanoscale pores are relatively high. The difference in the microscopic distribution of fluids with the two test methods is mainly caused by the different capillary forces inside the pores， while the difference between the two types of cores is primarily due to the difference in their main flow channels.

Yufeng Zou

Pattern database (PDB) is one of the most popular automated heuristic generation techniques. A PDB maps states in a planning task to abstract states by considering a subset of variables and stores their optimal costs to the abstract goal in a look up table. As the result of the progress made on symbolic search over recent years, symbolic-PDB-based planners achieved impressive results in the International Planning Competition (IPC) 2018. Among them, Complementary 1 (CPC1) tied as the second best planners and the best non-portfolio planners in the cost optimal track, only 2 tasks behind the winner. It uses a combination of different pattern generation algorithms to construct PDBs that are complementary to existing ones. As shown in the post contest experiments, there is room for improvement. In this paper, we would like to present our work on refining the PDB construction mechanism of CPC1. By testing on IPC 2018 benchmarks, the results show that a significant improvement is made on our modified planner over the original version.

Andrew V. Sills

A refinement of the multinomial distribution is presented where the number of inversions in the sequence of outcomes is tallied. This refinement of the multinomial distribution is its joint distribution with the number of inversions in the accompanying experiment. An application of this additional information is described in which the number of inversions acts as a proxy measure of homogeneity (or lack thereof) in the sequence of outcomes.

Seo Hyun Kim, Keummin Ka, Yohan Jo et al.

For a human-like chatbot, constructing a long-term memory is crucial. However, current large language models often lack this capability, leading to instances of missing important user information or redundantly asking for the same information, thereby diminishing conversation quality. To effectively construct memory, it is crucial to seamlessly connect past and present information, while also possessing the ability to forget obstructive information. To address these challenges, we propose CREEM, a novel memory system for long-term conversation. Improving upon existing approaches that construct memory based solely on current sessions, CREEM blends past memories during memory formation. Additionally, we introduce a refining process to handle redundant or outdated information. Unlike traditional paradigms, we view responding and memory construction as inseparable tasks. The blending process, which creates new memories, also serves as a reasoning step for response generation by informing the connection between past and present. Through evaluation, we demonstrate that CREEM enhances both memory and response qualities in multi-session personalized dialogues.

Chaomin Shen, Yaomin Huang, Haokun Zhu et al.

Knowledge distillation has become widely recognized for its ability to transfer knowledge from a large teacher network to a compact and more streamlined student network. Traditional knowledge distillation methods primarily follow a teacher-oriented paradigm that imposes the task of learning the teacher's complex knowledge onto the student network. However, significant disparities in model capacity and architectural design hinder the student's comprehension of the complex knowledge imparted by the teacher, resulting in sub-optimal performance. This paper introduces a novel perspective emphasizing student-oriented and refining the teacher's knowledge to better align with the student's needs, thereby improving knowledge transfer effectiveness. Specifically, we present the Student-Oriented Knowledge Distillation (SoKD), which incorporates a learnable feature augmentation strategy during training to refine the teacher's knowledge of the student dynamically. Furthermore, we deploy the Distinctive Area Detection Module (DAM) to identify areas of mutual interest between the teacher and student, concentrating knowledge transfer within these critical areas to avoid transferring irrelevant information. This customized module ensures a more focused and effective knowledge distillation process. Our approach, functioning as a plug-in, could be integrated with various knowledge distillation methods. Extensive experimental results demonstrate the efficacy and generalizability of our method.

Lukas Kölsch, Lucas Krompholz, Gohar M. Kyureghyan

Brawley and Carlitz introduced diamond products of elements of finite fields and associated composed products of polynomials in 1987. Composed products yield a method to construct irreducible polynomials of large composite degrees from irreducible polynomials of lower degrees. We show that the composed product of two irreducible polynomials of degrees $m$ and $n$ is again irreducible if and only if $m$ and $n$ are coprime and the involved diamond product satisfies a special cancellation property, the so-called conjugate cancellation. This completes the characterization of irreducible composed products, considered in several previous papers. More generally, we give precise criteria when a diamond product satisfies conjugate cancellation. For diamond products defined via bivariate polynomials, we prove simple criteria that characterize when conjugate cancellation holds. We also provide efficient algorithms to check these criteria. We achieve stronger results as well as more efficient algorithms in the case that the polynomials are bilinear. Lastly, we consider possible constructions of normal elements using composed products and the methods we developed.

Eghbal Motaei, Tarek Ganat, Khairul Azhar et al.

This paper provides a comprehensive overview of Deep Transient Testing (DTT), a cutting-edge technique for reservoir characterization that has revolutionized the oil and gas industry. The main aim of DTT is to characterize the reservoir with a deeper radius of investigation. The optimization of the radius of investigation with the DTT approach is studied in detail. Reveal is a commercial numerical simulation application used to simulate the DTT process and evaluate the pressure wave analysis in the porous media. The main aim of the simulation is to understand the impact of the reservoir quality on the pressure response and use it to address the noise-to-pule ratio, which is a determinantal parameter in testing duration. The tested wells with the DTT tool show that measured well productivity can deliver the minimum commercial rate. The has been delivered within 2 days compared to the potential test time of 21 days which saved the 19 rig days and contributed to CO2 emission reduction of (gas flaring 1340 + rig emission 600) 1940 Metric tons equivalent to 421 cars emission in a year. However, DTT also presents certain limitations, such as the requirement for specialized equipment and expertise, as well as the potential for formation damage during testing. This study provides a detailed description of the DTT technique, encompassing its history, theory, and practical applications. Furthermore, it discusses the benefits and limitations of DTT and presents case studies to illustrate its effectiveness across various reservoir types. Overall, this study serves as a valuable resource for reservoir engineers, geologists, and other professionals involved in the exploration and production of oil and gas.

TANG Jiandong, WANG Zhilin, GE Zhengjun

CCUS（Carbon capture, Utilization and Storage） technology is of great significance to the green and low-carbon transformation and the realization of the “dual carbon” goal, It includes important strategies like CO₂ enhanced oil recovery（EOR） and sequestration. Jiangsu Oilfield has been focusing on CO₂ EOR to improve recovery rates in the challenging fault block reservoirs of the Subei Basin. The company has developed four unique CO₂ EOR models suitable for these complex reservoirs, featuring techniques like gravity-stable displacement. A notable achievement is the successful pilot of the methods such as “simulated horizontal well” GAGD technology in Hua-26 fault block, which led to the one hundred thousand CCUS project tailored for such reservoirs. According to statistics, Jiangsu Oilfield has injected a total of 30.34×10⁴ t of liquid CO₂, with a cumulative oil increase of 9.83×10⁴ t, realizing a better production increase and economic benefits. These technical researches and tests can provide valuable insights for applying CO₂ EOR in similar complex reservoirs.

Mudiaga Chukunedum Onojake, Nsikan Edet Nkanta, Joseph Onyekwelu Osakwe et al.

Abstract Geochemical and biomarker characteristics of representative crude oil samples from selected fields in southern Nigeria were evaluated to determine the organic matter input, origin of biological material, depositional environment, thermal maturity, and genetic relationship between the oils. Four crude oil samples were obtained from various oil producing fields from Delta, Bayelsa and Abia state in southern Nigeria and labeled Kwale (KW), Kolo creek (KLC), Owaza (OWA1 and OWA2). The crude oil samples were fractionated into saturates, aromatic hydrocarbons and polar compounds using column chromatography on silica gel thereafter, analyzed using Gas chromatography-mass spectrometry (GC–MS). The calculated ratios of normal alkanes, acyclic isoprenoids, carbon preference index (CPI), hopanes, and steranes showed the following results: Pr/Ph (0.34 to 0.89); C29/C27 (0.78 to 1.25); 20S/(20S + 20R)C29sterane (0.28 to 0.66); 22S/(22S + 22R)C32 homohopane (0.17 to 0.23); CPI (0.96 to 0.98); Ts/Ts + Tm (0.46 to 0.50); and sterane/hopane (0.16 to 0.87). The results obtained were used to correlate the crude oils with respect to depositional environment, thermal maturity, and organic matter source. The Pr/Ph ratios of KW and KLC were less than one, and the cross-plot of Pr/nC17 versus Ph/nC18 of KW and KLC suggested that the oils were deposited under anoxic environments, whereas OWA1 and OWA2 indicated oxic conditions with no biodegradation. From the calculated ratios of 22S (22S + 22R)C32 homohopane and CPI, the oils were mature and had entered the generating window. Sample OWA1 is the most mature, while KLC is the least mature. The calculated ratios also showed that the four oil samples were from a shale source rock with both terrestrial and marine inputs.

Boning Zhang, Eric B. Herbold, Richard A. Regueiro

Granular material is showing very often in geotechnical engineering, petroleum engineering, material science and physics. The packings of the granular material play a very important role in their mechanical behaviors, such as stress-strain response, stability, permeability and so on. Although packing is such an important research topic that its generation has been attracted lots of attentions for a long time in theoretical, experimental, and numerical aspects, packing of granular material is still a difficult and active research topic, especially the generation of random packing of non-spherical particles. To this end, we will generate packings of same particles with same shapes, numbers, and same size distribution using geometry method and dynamic method, separately. Specifically, we will extend one of Monte Carlo models for spheres to ellipsoids and poly-ellipsoids.

WEN Rou, LI Dong, HUANG Ke et al.

The wave field data which is monitored the fracturing crack by micro seismic in the well is complex, especially when the shear wave (S-wave) encounters the fracture. The shear wave will split into the fast or slow wave. The polarization directions of the two kinds waves are perpendicular to each other. The identification of the shear wave field, the longitudinal wave (P-wave) field and fast or slow wave field, will directly affect the accuracy of the interpretation results. In order to improve the accuracy of interpretation results of microseismic data in wells, the wave field characteristics of waves in three-component geophone are analyzed according to the relationship between different incidence angles and the three components of the geophone, and it is concluded that the inversion results of the S-wave splitting event will cause fracture interpretation errors. Taking the micro-seismic fracture monitoring data of the Xinping XX well as an example, collect the micro-seismic records data of the P-wave, S-wave and fast/slow shear waves separately. Using the travel time inversion positioning algorithm of the first break collecting of the P/S waves, complete the micro-seismic positioning inversion of the P-wave+S-wave, fast S-wave +slow S-wave, P-wave+fast S-wave+slow S-wave fields. Through comparison, it is found that the orientation and distance of microseismic event localization results using only P-wave and S-wave are more reliable, and the fracture morphology is more consistent with the fracture growth law. At the same time, the influence of fast and slow S-wave on microseismic localization inversion results is fully explained.

Fumei Li, Mingqing Hua, Yanchen Wei et al.

High-sulfur petroleum coke (HSPC), that is a by-product from slag oil in the coking process of refining, shows versatility values in practical applications and, however, concentrates the majority of organic sulfur. Herein, we design and construct a highly effective CTAB@HPA composites to be explored for the catalytic oxidative desulfurization of HSPC under mild conditions using hydrogen peroxide as the oxidant and 1-butyl-3-methylimidazole tetrafluoroborate ionic liquid as the extractant. The results demonstrate that the sulfur content of HSPC could be strikingly reduced from 4.46 wt% to 2.48 wt% under 60 °C and atmospheric pressure, and that the organic sulfur in HSPC is mainly oxidized to sulfoxide, sulfone and sulfate, which latter can be directly separated from petroleum coke. Moreover, the effect of reaction conditions on the desulfurization performance of HSPC as well as the catalytic oxidation reaction kinetic of HSPC desulfurization was systematically investigated. Furthermore, a mechanism for the oxidative desulfurization of HSPC over CTAB@HPA catalysts was proposed. Therefore, this work provides new insight into how to construct active catalysts for the desulfurization of HSPC under mild conditions.

Luo Yi, Huang Zhongwei, Shi Huaizhong et al.

Conventional hydraulic fracturing technology faces problems such as high fracture initiation pressure and difficult packer setting in the stimulation of hot dry rock reservoirs. Supercritical nitrogen jet fracturing technology uses fluid pressure energy to coact with cold shock and is expected to achieve effective fracturing of hot dry rock reservoirs. In order to study the distribution law of supercritical nitrogen jet flow field, with the help of computational fluid mechanics method, after having considered the physical property variation of supercritical nitrogen, this paper figured out the velocity and pressure and temperature distribution of supercritical nitrogen jet flow field, conducted comparative analysis with liquid nitrogen jet, supercritical CO₂ jet and water jet flow fields, and simultaneously studied the flow field characteristics of supercritical nitrogen jet at different drawdowns, confining pressures and inlet temperatures. The study results show that compared with the other three jets, the supercritical nitrogen jet has the largest nozzle exit velocity and the longest potential core of jet; as the nozzle pressure drawdown increases and the supercritical nitrogen inlet temperature rises, the outlet velocity of fluid increases rapidly and the length of potential core increases; and the confining pressure has little effect on nozzle exit velocity, but the increase of confining pressure would lead to the decrease of potential core length. The study results provide theoretical guidance for the design of supercritical nitrogen jet fracturing stimulation parameters.

Yu Ren, Zuwei Liao, Jingyuan Sun et al.

Abstract Molecular reconstruction is popular in current oil refinery modeling. It aims to understand the refining process from the molecular level, to predict product properties accurately, to optimize the processes, and to increase the value of each molecule. Molecular reconstruction technique determines the detailed molecular composition of petroleum fractions through obtainable bulk properties and chemical details. In this paper, the existing molecular reconstruction models involving models with a set of predefined deterministic molecules, stochastic reconstruction method, structure-oriented lumping method, molecular type-homologous series matrix method, reconstruction by entropy maximization method, stochastic reconstruction-entropy maximization method and state space representation method are reviewed and compared. The credibility of the simulated composition and the drawbacks of molecular reconstruction technique are also discussed.

František Synák, K. Čulík, V. Rievaj et al.

Abstract Liquefied petroleum gas, known as LPG, is used as an alternative fuel for vehicles with a combustion engine. LPG is a mixture of propane, butane and other substances of a small amount and it is obtained as a by-product of being manufactured during the refining of petroleum. The purpose of this article lies in the assessment of LPG as an alternative fuel. The article includes the classification of LPG from the economic and safety point of view. It also assesses liquefied petroleum gas as an alternative fuel in terms of emission production.

Rosa Elvira Correa Pabón, Carlos Roberto de Souza Filho, W. Oliveira

Accidental releases of hazardous waste related to the extraction, refining, and transport of oil and gas are inevitable. Petroleum facilities and intrinsic pipelines present environmental pollution risks, threatening both human health and ecosystems. Research has been undertaken to enhance the conventional methods for monitoring hazardous waste problems and to improve time-consuming and cost-effective ways for leak detection and remediation process. In this study, both diffuse and imaging (hyperspectral) reflectance spectroscopy are used for detection and characterization of petroleum hydrocarbon (PHC) contamination in latosols. Laboratory and field measurements of PHC-contaminated and PHC-free soils were collected from an oil facility using an ASD FieldSpec-3 high-resolution portable spectrometer (2150 channels) covering visible, near infrared and shortwave infrared wavelengths (VNIR-SWIR: 350-2500 nm). The hyperspectral image dataset was acquired with the ProSpecTIR-VS airborne sensor using 357 channels in the VNIR-SWIR range at 1 m of spatial resolution. Narrow intervals of reflectance spectra were analyzed to identify the primary mineral and PHC absorption bands in soil samples and to investigate the spectral match with airborne hyperspectral data. The Multiple Endmember Spectral Mixture Analysis (MESMA) method was employed in three hierarchical levels to classify the hyperspectral imagery. The classification product yielded from MESMA model at the fourth level was 98% accurate in discriminating contaminated soils. The results demonstrated the applicability of both diffuse reflectance and imaging (hyperspectral) spectroscopy to identify bare soils contaminated by PHC leaks and spills. These technologies can also provide useful information for remediation initiatives, thereby avoiding further problems with hazardous waste.