Hasil untuk "Petroleum refining. Petroleum products"

Xiaoming Wang, Junbin Chen, Hao Wang et al.

Abstract The development of natural fractures can easily lead to horizontal wellbore instability caused by stress concentration after drilling in shale reservoirs, which is not conducive to the safe development of shale gas, but how different natural fractures impact the horizontal wellbore stability in shale reservoirs is still unclear. Therefore, the effect of single straight, intersecting, and T-shaped natural fractures on horizontal wellbore stability in shale reservoirs is studied. Then a stress distribution model around the horizontal wellbore in shale reservoirs considering natural fractures is established based on linear elasticity theory, the stress distribution around horizontal wellbores in shale reservoirs with single straight, intersecting, and T-shaped natural fractures is acquired through the finite element method (FEM), and the effect of different natural fractures on horizontal wellbore stability is analyzed finally. Results show that among three types of natural fractures, intersecting natural fractures relieve the maximum stress of 1.676 × 106Pa, and the horizontal wellbore is the most stable; T-shaped natural fractures have the largest effect on total stress around the horizontal wellbore, which is the largest and can reach 68.105 × 106Pa, which makes the wellbore the most unstable; single straight natural fractures and intersecting natural fractures can cause the maximum circumferential stress on the wellbore wall respectively in the two directions of the maximum horizontal principal stress and the vertical principal stress, and wellbore wall is prone to compression and tensile failure respectively; circumferential stress and total stress around horizontal wellbore are the largest in the direction of the maximum horizontal principal stress, the wellbore is the most unstable. This work will be helpful for a more reliable assessment of borehole instability and benefit the drilling design in shale reservoirs with single straight, intersecting, and T-shaped natural fractures.

Heikki Mäntysaari, Anh Dung Le

We revisit the calculation of exclusive $\mathrm{J}/ψ$ production in electron-proton scattering within the QCD dipole model, employing a refined description of the proton in terms of gluonic hot spots in the dilute regime. In contrast to earlier studies, we incorporate key missing elements: the event-by-event fluctuations in both the number of hot spots and their local saturation scales, as well as the first relativistic corrections to the $\mathrm{J}/ψ$ wave function. We perform a Bayesian analysis to constrain the model parameters using HERA data. These enhancements significantly improve the agreement with HERA data. Saturation scale fluctuations are found to be more important than fluctuations in the number of hot spots. Including the first relativistic correction is found to be important, especially in order to describe the observed power-law behavior in the incoherent cross section at large $t$.

G. Bonelli, A. Shchechkin, A. Tanzini

In this paper we study strong coupling asymptotic expansions of ${\mathcal N}=2$ $D=4$ $SU(2)$ gauge theory partition functions in general $Ω$-background. This is done by refining Painlevé/gauge theory correspondence in terms of quantum Painlevé equations, obtained from $\mathbb{C}^2/\mathbb{Z}_2$ blowup relations. We present a general ansatz and a systematic analysis of the expansions of the gauge theory partition functions by solving the above equations around the strong coupling singularities, including Argyres-Douglas points. We compare our results with refined holomorphic anomaly equations and irregular Virasoro conformal blocks.

Sijing Tu, Aleksa Stankovic, Stefan Neumann et al.

Data-analysis tasks often involve an iterative process, which requires refining previous solutions. For instance, when analyzing dynamic social networks, we may be interested in monitoring the evolution of a community that was identified at an earlier snapshot. This task requires finding a community in the current snapshot of data that is ``close'' to the earlier-discovered community of interest. However, classic optimization algorithms, which typically find solutions from scratch, potentially return communities that are very dissimilar to the initial one. To mitigate these issues, we introduce the \emph{OptiRefine framework}. The framework optimizes initial solutions by making a small number of \emph{refinements}, thereby ensuring that the new solution remains close to the initial solution and simultaneously achieving a near-optimal solution for the optimization problem. We apply the OptiRefine framework to two classic graph-optimization problems: \emph{densest subgraph} and \emph{maximum cut}. For the \emph{densest-subgraph problem}, we optimize a given subgraph's density by adding or removing $k$~nodes. We show that this novel problem is a generalization of $k$-densest subgraph, and provide constant-factor approximation algorithms for $k=Ω(n)$~refinements. We also study a version of \emph{maximum cut} in which the goal is to improve a given cut. We provide connections to maximum cut with cardinality constraints and provide an optimal approximation algorithm in most parameter regimes under the Unique Games Conjecture for $k=Ω(n)$~refinements. We evaluate our theoretical methods and scalable heuristics on synthetic and real-world data and show that they are highly effective in practice.

Xinnian Zhao, Hugo Van Hamme

This study proposes a novel approach to using TV subtitles within a weakly supervised (WS) Automatic Speech Recognition (ASR) framework. Although TV subtitles are readily available, their imprecise alignment with corresponding audio limits their applicability as supervised targets for verbatim transcription. Rather than using subtitles as direct supervision signals, our method reimagines them as context-rich prompts. This design enables the model to handle discrepancies between spoken audio and subtitle text. Instead, generated pseudo transcripts become the primary targets, with subtitles acting as guiding cues for iterative refinement. To further enhance the process, we introduce a weighted attention mechanism that emphasizes relevant subtitle tokens during inference. Our experiments demonstrate significant improvements in transcription accuracy, highlighting the effectiveness of the proposed method in refining transcripts. These enhanced pseudo-labeled datasets provide high-quality foundational resources for training robust ASR systems.

XU DAN, ZHANG CONG, JIA HUIMIN et al.

Helium is a crucial strategic resource with very limited reserves, but its enrichment and dilution mechanisms in gas reservoirs remain unclear. Noble gas isotopes play an important role in characterizing the interactions between gas and groundwater. In this study, noble gas compositions and isotopic signatures of coalbed methane (CBM) from the third coal seam in the southern Qinshui Basin were analyzed to determine the isotope composition characteristics of noble gas and to establish a helium reservoir formation model. Gas samples were collected from 13 CBM production wells. The results showed that the helium (He) content in CBM was generally one order of magnitude higher than in the atmosphere. The ³He/⁴He ratios were 0.002 9-0.021 8 <italic>R</italic>_a, with a very low mantle source contribution (0-0.31%). The ²⁰Ne/²²Ne ratios (10.09-10.43) and ²¹Ne/²²Ne ratios (0.029 6-0.031 9) were slightly higher than those in the atmosphere, reflecting an excess of ²¹Ne relative to the atmosphere. The ⁴⁰Ar/³⁶Ar ratios (295.23-779.44) were overall higher than the atmospheric values, suggesting a significant influence of crustal ⁴⁰Ar accumulation over time. The isotopic signatures of krypton (Kr) and xenon (Xe) were similar to those of the atmosphere. Quantitative calculations of helium production revealed an external ⁴He flux into the self-generating and self-preserving CBM system. The linear relationship between ⁴He and ²⁰Ne indicated that helium dissolved in groundwater before degassing into the gas reservoir, while methane desorbed from coal seams diluted helium (as well as neon and argon) in the groundwater-associated gases. Therefore, gas reservoirs with lower grades were more likely to accumulate helium. Helium was mainly distributed in areas with effective helium source rocks, ancient groundwater systems, efficient migration channels, and appropriate hydrocarbon generation intensity, providing a theoretical basis for exploring helium resources in CBM. Rayleigh fractionation, dilution modelling, and gas production quantification showed that the water output per well during gas production was 8.03×10³-1.63×10⁶ m³. CBM exploration affected only the local water around each well, offering a basis for optimizing well spacing design.

Livshits V.R.

The probabilistic distribution of hydrocarbon accumulations by their mass is the most important characteristic of an oil and gas basin, which is of theoretical interest for both the theory of naphtido-genesis and for assessing the structure of the basin's resources. Computational experiments performed on a simulation stochastic model showed that the power-law distribution of hydrocarbon accumulations by mass can be a consequence of the process of lateral migration of primary accumulations in the near-roof zone of the reservoir. It was also established that two oppositely directed factors play a key role in forming the power-law distribution: displacement and merging of primary accumulations and loss of their mass along migration paths.

YU Fengmei, WANG Xiao, LIU Jiayin et al.

Rhamnolipids are biodegradable and environmentally friendly surfactants with low toxicity， high stability， and other advantages. In the oil and gas development field， they have broad application value and prospects. This paper reviewed the progress in the application of rhamnolipids in oil and gas development， discussed its production methods， characteristics， and current status， and provided new ideas for the green and sustainable development of oil and gas development. The paper first introduced the two production methods of rhamnolipids： enzymatic and fermentation. Then， the authors elaborated in detail on the characteristics of rhamnolipids in reducing surface tension， emulsification and demulsification， solubilization， and coiling， as well as the suitable conditions. In addition， the new anti-aggregation characteristics discovered by recent scholars were clarified. The paper focused on summarizing the five main application directions of rhamnolipids in oil and gas development： in terms of reducing viscosity of heavy oil， rhamnolipids can effectively reduce the viscosity of heavy oil and enhance oil recovery； in terms of treating oil-contaminated soil and water， rhamnolipids show excellent emulsification performance and can separate oil from soil and form easy-to-treat emulsion； in terms of promoting hydrate generation， rhamnolipids can reduce the induction time of hydrates and improve the generation rate and stability of hydrates； in terms of oil and gas pipeline transportation， the anti-aggregation characteristics of rhamnolipids can help solve the problem of pipeline blockage； the authors finally proposed the following research suggestions for the future： in terms of production method， it is necessary to increase the research and application of local extraction strains； in terms of characteristic research， it is necessary to explore the other functional characteristics of rhamnolipids besides the existing ones and expand its application scopes in oil and gas development； in terms of application， it is important to study the recyclable use of rhamnolipids and the synergistic application of multiple technologies to solve problems such as high development costs in super-heavy oil production. At present， the application research of rhamnolipids in the frontier oil and gas fields such as hydrates is not complete， and further in-depth exploration is needed.

Zhi Chen, Tianqi Wei, Zecheng Zhao et al.

In modern agriculture, precise monitoring of plants and fruits is crucial for tasks such as high-throughput phenotyping and automated harvesting. This paper addresses the challenge of reconstructing accurate 3D shapes of fruits from partial views, which is common in agricultural settings. We introduce CF-PRNet, a coarse-to-fine prototype refining network, leverages high-resolution 3D data during the training phase but requires only a single RGB-D image for real-time inference. Our approach begins by extracting the incomplete point cloud data that constructed from a partial view of a fruit with a series of convolutional blocks. The extracted features inform the generation of scaling vectors that refine two sequentially constructed 3D mesh prototypes - one coarse and one fine-grained. This progressive refinement facilitates the detailed completion of the final point clouds, achieving detailed and accurate reconstructions. CF-PRNet demonstrates excellent performance metrics with a Chamfer Distance of 3.78, an F1 Score of 66.76%, a Precision of 56.56%, and a Recall of 85.31%, and win the first place in the Shape Completion and Reconstruction of Sweet Peppers Challenge.

LIU Feng, HAN Chunshuo, YU Linjun et al.

Surfactants are widely used in the tertiary recovery of oilfields， and it is of great significance to study the mechanism of surfactant flooding from the microscopic point of view. In recent years， molecular dynamics （MD） simulation has become essential for oil and gas field development research. The use of MD simulation to study surfactants has become a hot spot. Through MD simulation， the numerical solutions of Newton’s equations are calculated for all the moving particles in the system， and the change in atomic positions with time is analyzed， from which some laws are found. MD simulation can be used to study the microscopic behavior of surfactant molecules to explore the properties of surfactant molecules and the microscopic flooding mechanism. MD simulation of the movement and aggregation state of surfactants at the interface and the analysis of the influence of surfactant molecules at the interface on the interfacial system are of some guiding significance for the field application of surfactants. To this end， based on the principle overview of MD simulation， firstly， the force field， boundary conditions， system types， and numerical algorithms in MD simulation are summarized； secondly， the microscopic mechanisms of MD simulation of surfactant flooding are highlighted， including the reduction of oil-water interfacial tension， the change in surface wettability， the increase in interfacial charge and emulsification， etc.； then， examples of the application of MD simulation in surfactant flooding are presented. Finally， the development directions of MD simulation technology in surfactant flooding are proposed， including the flooding environment similar to production， the design of new surfactants， the relationship between theory and experiment， the selection of molecular force field and potential energy model， and the research and development of composite and multifunctional integrated surfactants.

Pu Cao, Lu Yang, Dongxv Liu et al.

Recently, inversion methods have focused on additional high-rate information in the generator (e.g., weights or intermediate features) to refine inversion and editing results from embedded latent codes. Although these techniques gain reasonable improvement in reconstruction, they decrease editing capability, especially on complex images (e.g., containing occlusions, detailed backgrounds, and artifacts). A vital crux is refining inversion results, avoiding editing capability degradation. To tackle this problem, we introduce Domain-Specific Hybrid Refinement (DHR), which draws on the advantages and disadvantages of two mainstream refinement techniques to maintain editing ability with fidelity improvement. Specifically, we first propose Domain-Specific Segmentation to segment images into two parts: in-domain and out-of-domain parts. The refinement process aims to maintain the editability for in-domain areas and improve two domains' fidelity. We refine these two parts by weight modulation and feature modulation, which we call Hybrid Modulation Refinement. Our proposed method is compatible with all latent code embedding methods. Extension experiments demonstrate that our approach achieves state-of-the-art in real image inversion and editing. Code is available at https://github.com/caopulan/Domain-Specific_Hybrid_Refinement_Inversion.

LOU Zhanghua, ZHANG Xinke, WU Yuchen, GAO Yuqiao, ZHANG Peixian, JIN Aimin, ZHU Rong

The exploration and development of shale gas in Upper Ordovician Wufeng Formation to Lower Silurian Longmaxi Formation in Nanchuan and its adjacent blocks have yielded fruitful results. However, it is crucial to pay closer attention to the comprehensive use of fluid characteristics for analyzing the differences in shale gas preservation conditions in each block. Research findings reveal the following key points: ① With the prolongation of recovery time, the mineralization degree of the produced water gradually increases, exhibiting notable differences from fracturing fluid. This suggests the presence of the presence of movable CaCl2-rich formation water in shale layer, characterized by a mineralization degree exceeding 50 g/L; ② Enriched and high-yield wells exhibit low water production, low mineralization and rich in NaHCO3, which are indicative of condensate water; ③ Under different preservation conditions, the deuterium oxygen isotopes of the produced water vary with time. The high pressure stable block in the basin gradually deviates from the atmospheric precipitation line, while the normal（low） pressure complex block outside the basin remains close to the atmospheric precipitation line; ④ From the inside to the outside of the basin and from deep to shallow, the homogenization temperature of fluid inclusions in shale fracture filled calcite veins gradually decreases（from 240 ℃ to 90 ℃）. Simultaneously, the metamorphism coefficient of the inclusions also gradually increases, reflecting the degree of differential damage of shale gas preservation conditions.

Siyao Liu, Tong Wu, Yong Wang

In this paper, we generalize the results in [Y. Wang: Affine connections on singular warped products. Int. J. Geom. Methods Mod. Phys. 18(5), 2150076, (2021).] to singular multiply warped products and singular twisted products. We study singular multiply warped products and singular twisted products and their curvature with the semi-symmetric metric connection and the semi-symmetric non-metric connection. We also discuss Koszul forms associated with the almost product structure and their curvature of singular multiply warped products and singular twisted products. Finally, several examples are presented to demonstrate the theoretical results.

Daniel D. Forest

Demographics of the petroleum refining and petrochemical industries have shown an aging workforce nearing retirement and being replaced by a younger generation of workers who learn and were taught differently. To address the challenge of building competency in the young workforce, the Immersive Learning Committee was created by the American Fuel & Petrochemical Manufacturers (AFPM), a trade association representing nearly all U.S. refining and petrochemical manufacturing capacity. AFPM members produce the fuels that drive the U.S. economy and the chemical building blocks integral to millions of products that make modern life possible. This paper will show how the work of both AFPM and its members is helping bridge the knowledge gap between generations of employees and addressing competency training challenges by developing a digital library of tools—including virtual reality and augmented reality simulations, as well as three‐dimensional assets, and other resources—for broad industry use. The work also assists member companies with their own development of training tools tailored to their unique facilities, processes or company practices. The pilot project, a fired heater training simulation using virtual reality, will be discussed in the paper, as well as a set of leading metrics currently being developed that will help industry understand the effectiveness of the tools.

R. E. Moore, C. Rosato, S. Maskell

Estimates from infectious disease models have constituted a significant part of the scientific evidence used to inform the response to the COVID-19 pandemic in the UK. These estimates can vary strikingly in their bias and variability. Epidemiological forecasts should be consistent with the observations that eventually materialise. We use simple scoring rules to refine the forecasts of a novel statistical model for multisource COVID-19 surveillance data by tuning its smoothness hyperparameter.

Emanuele Bottazzi, Mikhail G. Katz

A refinement of the classic equivalence relation among Cauchy sequences yields a useful infinitesimal-enriched number system. Such an approach can be seen as formalizing Cauchy's sentiment that a null sequence "becomes" an infinitesimal. We signal a little-noticed construction of a system with infinitesimals in a 1910 publication by Giuseppe Peano, reversing his earlier endorsement of Cantor's belittling of infinitesimals.

P. Nowak, Karolina Kucharska, M. Kamiński

Mineral base oil, a product of multistep fine refining of the relevant fractions from vacuum distillation of crude oil, is a main component of so-called mineral lubricating oils containing aliphatic and alicyclic substituted aromatic hydrocarbons, i.e., derivatives of benzene and biphenyl. Mineral lubricating oil is composed mostly of mineral base oil and a low amount of enriching additives, most often products of advanced organic chemical technology. The application of mineral lubricating oils in open cutting systems has a very negative impact on environment and on the operator’s health. This work presents a simple, cheap and fast methodology allows identification of the group-type composition of base oil in lubricating oil and to estimate the content or total absence of base oil of mineral and vegetable origin in lubricating oil. The first step of the test is an in-situ screening for fluorescence of petroleum fraction under the 365 nm light. The next is the performance of infrared spectra with Fourier transformation (FT-MIR) to identify and estimate the content of vegetable oil and its derivatives and the performance of UV-Vis spectra to identify and determine the content of aromatic hydrocarbons, as well as dyes present in the lubricating oil. The last stage is normal phase thin layer chromatography (NP-TLC) using different visualization methods to evaluate the group-type composition of lubricating oil. Effectivity of the developed procedure has been confirmed during control of group-type composition evaluation of lubricating oils in cutting systems. The procedure can be also applied with respect to different oil matrices.

K. Motahari, Mohammad Abdollahi-Moghaddam, A. Rashidi

Abstract Sulfur-containing pollutants lead to reduced quality of end products and environmental problems. Mercaptans are one of those sulfur pollutants which not only are smelly and toxic but also have high corrosive property. Mercaptan catalytic oxidation is the most important method of oil production refining from mercaptan. Thus, cognition of the reaction kinetics and interrogation of effects of various factors on the process are of the most requirements of mercaptan removing units. Due to the inadequate efforts made on reaction kinetics determination of catalytic oxidation of light mercaptans available in liquefied petroleum gas (LPG), this study was done in this regards. First, rate-determining step (RDS) of reactions was determined by analyzing the experimental data obtained from the Merox unit. The experiments were carried out on a cobaltphthalocyanine liquid catalyst in a packed reactor. In order to better understand the process, design, and optimization, the kinetics were defined with respect to the limiting reaction. By investigating the effective parameters of the kinetics, it was determined that the mercaptide ion (RS-) confines the oxidation reaction rate and has the first order in the rate equation. Finally, optimal values were proposed for each of the parameters.

Mona Zehni, Laurène Donati, Emmanuel Soubies et al.

Single-particle cryo-electron microscopy (cryo-EM) reconstructs the three-dimensional (3D) structure of bio-molecules from a large set of 2D projection images with random and unknown orientations. A crucial step in the single-particle cryo-EM pipeline is 3D refinement, which resolves a high-resolution 3D structure from an initial approximate volume by refining the estimation of the orientation of each projection. In this work, we propose a new approach that refines the projection angles on the continuum. We formulate the optimization problem over the density map and the orientations jointly. The density map is updated using the efficient alternating-direction method of multipliers, while the orientations are updated through a semi-coordinate-wise gradient descent for which we provide an explicit derivation of the gradient. Our method eliminates the requirement for a fine discretization of the orientation space and does away with the classical but computationally expensive template-matching step. Numerical results demonstrate the feasibility and performance of our approach compared to several baselines.

Chai Lin, Zhang Kai, Liu Baolin et al.

The principle and advantages of automatic vertical drilling technology are introduced from the aspects of oil drilling and geological drilling. The automatic vertical drilling tools are classified according to different structures and working principles, and the advantages and disadvantages of each type of tools are briefly analyzed. Based on the classification, the vertical drilling tools and their technical characteristics are summarized systematically. The domestic and foreign technical gap of the automatic vertical drilling tool is analyzed. Finally, the problems of automatic vertical drilling tools and the development trend in the future are summarized. Miniaturization, coring capacity, high precision and long life are the development trend. Suggestions for future research ideas and methods include:optimization of the structure and layout of actuator components; reducing the outer diameter of the tool while increasing the internal space of the tool, thus enabling coring while vertically drilling in a small diameter wellbore; optimizing the measurement and control sensor and the sealing system of the electronically controlled vertical drilling tool to improve the overall temperature and pressure resistance; studying the response law of the heavy platform of the mechanical vertical drilling tool in complex downhole environment, and exploring the corresponding error suppression compensation method to improve the accuracy of the tool’s inclination control.