Hydraulic fracturing is widely employed to achieve commercial production in heterogeneous shale reservoirs with tight pore structure. However, interactions between the shale and fracturing fluids may lead to structural destabilization, significantly impact fluid migration pathways and hinder efficient resource recovery. This work explores mechanisms of pore structure evolution during fluid-rock interaction and its influence on transport in marine and continental shales using a combination of scanning electron microscopy, low-temperature nitrogen adsorption, X-ray diffraction, inductively coupled plasma mass spectrometry and fractal analysis. This is used to characterize the evolution of pore structures, mineral compositions and ionic concentrations in different shale lithofacies during interactions with various fluids under reservoir conditions. Evolving pore-fracture architectures are reconstructed with lattice Boltzmann methods employed to explore the impact of structural evolution on fluid flow. Compared with deionized water, infiltration by saline solutions reduces pore structure damage from clay hydration swelling, with KCl exhibiting a greater inhibitory effect than NaCl. Swelling reduces micro/mesopore volumes and lowers pore complexity in clay-rich shales. In contrast, dissolution reactions dominate in carbonate-rich shales, where carbonate minerals are consumed and Ca2+ and Mg2+ ions are liberated, generating dissolution pores that enlarge pore volume and increase structural complexity. Pore scale simulation results indicate that clay mineral swelling disrupts the connectivity between matrix pores and microfractures, thereby reducing the migration rate of the water phase. Compared with gaping microfractures, narrowed microfractures inhibit preferential water channeling and improve sweep efficiency. However, clay mineral swelling compromises the connectivity of the porous medium, ultimately resulting in a lower fluid recovery in the structurally altered model than in the original pore fracture model.

The laminae of varying lithologies are characteristic of shale oil reservoirs, with their pronounced heterogeneity and fluid-solid coupling significantly impacting oil productivity. To this end, this study initially quantified the permeability and mechanical heterogeneity in lamina-developed shale through permeability tests and quasi triaxial mechanical experiments on shale cores from different orientations in the Jiyang Depression. These tests revealed marked brittleness in horizontally oriented cores and elasticity in vertically oriented cores. Subsequently, the strong fluid-solid coupling in lamina-developed shale formations was hereby investigated by permeability stress sensitivity experiments and CT scanning, which presented the dynamic opening and closing of laminae and strong fluid-solid coupling in horizontal direction during the fracturing shut-in and production (FSP). Based on online nuclear magnetic resonance (NMR), fluid migration in pores of different scales and laminae during the FSP was discovered. To detail the fluid seepage mode in lamina-developed shale oil reservoirs during FSP, an oil-water two-phase flow model coupling shale matrix, laminae, and hydraulic fractures was further simulated, based on the permeability heterogeneous and stress sensitivity, to delve into the variation in saturation, pressure, relative permeability, and streamlines of water in lamina-developed shale cores. The results showed that during the hydraulic fracturing, the horizontal brittleness, and vertical elasticity created a seepage channel composed of shale matrix, horizontal seams, and vertical hydraulic fractures. During the shut-in period, the expanded seepage area resulting from the opening of the laminae, combined with the extremely high pressure gradient from the seam to the matrix, facilitated the invasion of fracturing fluid into the matrix, displacing shale oil and gradually balancing the pressure among the three seepage media. During production, the extremely high pressure gradient shifted from the matrix to seams and hydraulic fractures, and oil and water were simultaneously extracted. However, due to stress sensitivity and variations in relative permeability, fracturing fluid remained trapped in the shale formation.

Double-row spherical roller bearings are frequently employed as supporting components in mining machinery. In practice, these bearings are lubricated manually, and the bearing chamber is filled with grease, which can lead to issues such as grease wastage and increased bearing temperatures. Additionally, factors such as load and speed also influence the bearing temperature, collectively contributing to inadequate lubrication and potential bearing failure. Consequently, it is essential to investigate the temperature of the bearing under operating conditions. Utilizing tribology theory and the principles of bearing heat generation, a numerical model of fluid–structure interaction heat transmission within the bearing was developed, and finite element analysis was conducted through the ANSYS-Fluent module. The model was verified, and the temperature field of the bearing under varying operating conditions was studied. The findings of this research are as follows: (1) The numerical model demonstrates high accuracy, with a relative error of less than 5% when comparing the experimental temperature values of the jaw crusher bearing to the simulated values. (2) Under diverse operating conditions, the inner ring of the bearing has the highest temperature of all parts of the bearing, while the bearing cavity’s flow field has the lowest temperature. (3) The average temperature amplitude across different areas of the bearing system will rise as a result of increases in radial load or the bearing rotational speed. (4) When the grease filling volume increases from minimal to maximal, the average temperature in each bearing area initially decreases before subsequently rising, with the optimal grease filling amount identified as 60%. In operational scenarios, if the bearing temperature exceeds 70 °C, it is imperative to shut down the machine immediately to avert bearing failure. This study on bearing lubrication has practical guiding significance.

Shale is characterized by a complex mineral composition and a well-developed, multiscale pore network spanning from micropores to nanopores, which gives rise to a highly intricate microscopic imbibition mechanism. Utilizing shale samples from the Jiyang Depression, experiments are conducted to systematically examine the influence of lithofacies, fluid type, fracture density, wettability, and fluid viscosity on the spontaneous imbibition behavior of shale. Low-field nuclear magnetic resonance serves as the principal analytical method for investigating fluid migration dynamics and spatial distribution within the multiscale pore structure of shale. The results indicate that, at the microscopic scale, imbibition-driven oil recovery is primarily controlled by capillary forces, which must overcome various forms of resistance to effectively displace oil with water. For massive cores without fracture, oil recovery is primarily contributed by nanopores within the matrix. In contrast, cores containing laminations and natural fractures preferentially mobilize oil from larger pores, as the flow resistance in nanopores is significantly greater than that in micropores. Transverse relaxation time spectrum from nuclear magnetic resonance further reveals that CO2, compared to water, can mobilize more oil from large pores via molecular diffusion. However, water exhibits superior displacement efficiency in smaller pores. Hydrophilic cores demonstrate the highest imbibition efficiency, and the addition of imbibition enhancers further improves displacement performance. On the other hand, increasing fluid viscosity suppresses both the imbibition-driven displacement process and overall fluid mobility.

During the unconventional hydrocarbon development, the irregular shaping and uneven sand concentration of proppants banks in the staged multi-cluster fracturing of horizontal wells are key factors determining the fracture conductivity and post-fractured well productivity. To compensate for the limitation of small-scale sand filled core conductivity research that cannot accurately reflect the fracture conductivity at the field scale, this study used the mixture model to investigate the proppant distribution in fractures after sand carrying fluid enters the multi-cluster fractures from a horizontal well section, and divided the fractures into several regions based on different sand concentration ranges inside hydraulic fractures. The mechanical parameters and permeability of the sand embankment in each region were regressed to the entire fracture. The closure and conductivity of field-scale fractures with non-uniform sand filled were studied using elastic mechanics theory and free and porous media flow theory. Effects of fracture width and height on the conductivity of field-scale fractures were analyzed. The results indicate that reducing the fracture width, from 10 to 6 mm, and fracture height, from 12 to 6 m, can increase the proportion of fracture areas with sand concentration from 12 to 15%; Configurations of areas with different sand concentrations in fractures are irregular, and some areas without proppant filling can be closed under the closure pressure of 70 MPa, causing the surrounded sand filling areas to fail providing flowing paths; Sand banks with proppant concentration between 0 and 6% at the top part of the fracture can provide a more permeable flow channel than the bottom part during the initial closure of the fracture. While sand banks with proppant concentration between 12 and 15% at the bottom of the fracture can maintain a higher permeability than the top part when the closure pressure reaches 70 MPa; Reducing the width and height of the fracture can still maintain a larger fracture width when the closure pressure exceeds 60 MPa.

The Jiyang Depression has abundant shale oil resources, and elastic development is the main way to utilize shale oil. As the pore pressure decreases, the bedding fractures, sand filled fractures, and pores undergo deformation under compression, leading to a decrease in permeability/conductivity, which affects the permeability and development effectiveness of shale. Based on the liquid pressure pulse experiment, the variation law of the permeability of shale containing bedding fractures in elastic development was clarified, supplemented by online CT displacement testing, to study the changes in the morphology and quantity of bedding fractures in fracturing elastic development. Experimental studies have shown that the permeability of shale with bedding fractures decreases exponentially and linearly with the increase of effective stress. There is a clear turning point in the exponential decrease, and the closure pressure is around 30 MPa, indicating strong stress sensitivity; The linearly decreasing core exhibits moderate to strong stress sensitivity; After secondary loading pressure, the permeability of the core decreases irreversibly. The permeability of the core decreases approximately linearly with the increase of effective stress, and the stress sensitivity of the core becomes moderately weak; During the process of hydraulic fracturing and pressure increase, the volume of bedding fractures increases, while during the process of elastic pressure failure, the volume of bedding fractures decreases. However, the magnitude of change is smaller than that of the pressure increase process, and the stress sensitivity is relatively weak. The study innovatively utilized liquid pressure pulse stress sensitivity experiments combined with CT scanning technology to clarify the stress sensitivity of shale bedding fractures and visually display them, providing technical support for achieving large-scale development of shale oil.

Current fluorescent labels are often expensive and environmentally unfriendly and tend to lose their fluorescence when combined with dry and hydrophilic substrates because of their hydrophobic nature. Thus, the development of environmentally friendly, low-cost, and scalable fluorescent materials is still highly desirable but significantly challenging, especially for anti-counterfeiting and food quality monitoring. In this study, highly fluorescent nanoparticles were prepared by mimicking organelles and using natural and sustainable curcumin as a fluorescent component. The preparation process was easily scalable via traditional seeded emulsion polymerization methods and green without using additional organic solvents. The resulting curcumin-based fluorescent nanoparticles (CFNs) were well dispersed in water, offering smart fluorescence in water-based environments or a dried polymer coating. In particular, CFNs-based coatings could be used for effective smart anti-counterfeiting and food quality monitoring. The proposed strategies may inspire the design of novel, green, and sustainable smart fluorescent materials/coatings for applications in anti-counterfeiting, smart food tags and labels, and visual sensing systems.

By conducting tests on the flow capacity of shale fractures with different degrees of sand filling and conducting online CT scans on samples of different lithologies, it is recognized that as the sand concentration increases, the flow conductivity of sand-filled fractures increases and stress sensitivity decreases. Under low effective stress, the large particle size proppant filled sand fractures have higher diversion capacity. As the effective stress increases, the reduction in diversion capacity is significant, and the stress sensitivity is small. The particle-size-filled sand layer is strong. During the process of elastic pressure reduction and failure, the proppant is compacted, the pores of the sand layer are reduced, the crack width is reduced, and the conductivity is reduced.

In order to explore the change of pore structure during the development of matrix and laminated reservoirs and to determine the factors affecting the reservoir physical properties on the recovery factor. On the basis of the pore pressure rise experiment and the pore pressure drop experiment, the core porosity change was quantitatively characterized by the nuclear magnetic resonance T2 spectrum testing technology, and the dynamic change process of shale pore structure and the influencing factors of shale oil elastic recovery were studied. The results show that when the pore pressure increases from 4 MPa to 20 MPa, the porosity increases to 127

In situ viscosity has an important influence on the seepage process in tight oil development. Online NMR (nuclear magnetic resonance) analysis technology can nondestructively analyze the fluid recovery in the core and the change of in situ viscosity during the development experiment. Through the online NMR physical simulation experiment of displacing crude oil in three typical tight reservoir samples, the NMR T2 spectra and stratification T2 spectra are tested in the experiment process. The in situ viscosity change and its influence on development effect and nonlinear seepage are studied. The results show that the average boundary viscosity of the core after saturated oil is 612 mPa·s. During the development process, the decrease of in situ viscosity and seepage resistance of the core can be divided into two obvious stages with 1PV as the boundary, showing a trend of fast before slow after. The in situ viscosity at the drive front of core is calculated by stratification T2 spectra. In the development process, the influence of in situ viscosity is small in the early stage and large in the later stage. The charts of in situ viscosity changes in the development process of three tight oil areas in China are established, and the evaluation table of in situ viscosity classification of tight oil is proposed. The influence of in situ viscosity on nonlinear seepage is analyzed, and it is clear that most of the pores in the core are in nonlinear seepage state in the seepage process of tight core under pressure maintaining development. The seepage velocity increases rapidly in the early stage and slowly in the later stage.

[目的/意义]针对目前全领域科学知识图谱构建方法中存在的技术难点,结合网络嵌入模型、机器学习聚类、流形学习可视化算法等人工智能领域的方法与模型,提出一套全新发现科学结构的知识图谱构建方案,以完善科学结构发现与可视化布局,并拓展科学知识图谱的分析应用场景.[方法/过程]引入基于深度学习的网络嵌入模型和聚类方法改进原有的网络社团划分聚类方法,利用流形学习降维可视化算法扩大数据处理能力,并设计由下至上分层可视化布局方法,提升可视化图谱的稳定性与细节揭示能力.[结果/结论]以科睿唯安公司的基本科学指标数据库(ESI)研究前沿中高被引论文作为分析数据集,使用新聚类算法得到1169个研究领域,通过改进的可视化布局算法形成全领域科学结构图谱.与前几期科学结构图谱相比,本文提出的方法支持更大规模的数据分析,对可视化细节揭示与稳定性也有大幅优化,可以更好地展示全领域科学研究宏观结构及内在关系,为全领域科学知识图谱的绘制与构建提供更可靠的方法和技术支持.

The change of in situ viscosity in micro-scale of tight oil reservoir has great influence on the seepage process. Due to the imperfection of in situ viscosity model and measuring method, the prediction of development effect and scientific guidance is affected. Here, an in situ viscosity model of seepage fluid in tight reservoirs is established, and the main influencing factors are studied. The in situ viscosity changes linearly with the bulk viscosity; When the average pore radius less than 500 nm, the in situ viscosity increased sharply. The approximate properties of boundary fluid and heavy oil are verified by experiments, and a method for measuring boundary fluid viscosity based on nuclear magnetic resonance (NMR) is found. According to the viscosity property of boundary fluid, the experiment is designed to verify the measurement method of boundary fluid viscosity by NMR.

人工智能在近几年快速发展并成为最热门的技术之一,如能快速了解人工智能技术热点与发展态势,对抢抓人工智能发展的重大战略机遇与构筑先发优势具有重要意义.本文提出了一种基于专利可视化图谱发现技术热点的方法,即在连续时间窗口上绘制图谱,在此基础上运用密度分布变化来识别该领域技术热点.为了提升专利图谱的准确性,本文使用海量专利文本训练了基于深度学习的doc2vec模型,形成了专利文本特征抽取模型.经过实验对比发现该模型在测试数据集中表现远超经典的词袋模型与主题模型.在实例分析中使用了2012—2019年10457件三方人工智能专利进行热点发现,共发现研究热点7个,并对7个热点中关键概念词、专利申请人所属国家进行深入分析.

由于国家在一个时期内的科技投入的方向和强度最能反映出国家未来科技发展趋势,本研究提出构建基于科技投入和核心技术的政策要素知识图谱,意欲分析得出各国科技发展方向及趋势的情报,从而支撑科技发展布局与趋势研判.本研究总结了情报监测的科技政策文本中支撑情报分析的关键要素,提出了基于政策要素的知识图谱模型,探索了智能计算的政策分析方法.通过对美国、英国、法国、德国、日本和韩国近年科技投入的优先领域、技术、资助项目、资助强度等相关知识的信息抽取和内容分析,形成了基于领域的政策知识图谱,并利用两个实例演示了基于知识图谱的情报检索与分析效果.本技术对情报分析人员、决策人员审视宏观科技布局和前瞻科技发展方向有所帮助.

[目的]设计基于可视化的基金资助热点发现方法,用于分析科研立项重点以及发现其演化过程.[方法]基于NASA小企业研发计划基金申请书的文本特征,绘制连续时间窗口下基金资助图谱,通过识别图谱中项目密度分布较高的区域定位资助热点,并根据两期图谱中热点位置、内容变化分析研判资助热点演变趋势.[结果]在两个时间窗口内,可明确区分出消亡的、持续的和新兴的资助热点及其演化过程.[局限]分析方法中涉及文本特征提取、可视化与概率密度计算等多个步骤需要多次调优,热点与演化判断分析尚未形成计算指标,无法脱离领域专家的判读.[结论]本文提出的基于可视化图谱的基金资助热点及其演化的发现方法,可直观地反映资助机构的资助布局热点变化情况,经领域专家判读与其认知相符,或可在科研管理与决策者审视宏观科研布局中起到辅助作用.

Protein adsorption on polyelectrolyte (PE) surfaces has aroused intensive attraction, but there are still few investigations on tuning the protein adsorption at a solid surface by controllable layer structures and surface properties of PE adlayers. Furthermore, there is a lack of understanding regarding the correlation between molecular conformation and anticorrosion performance of composite materials. With this in mind, we synthesized a series of PEs and constructed 3,4-dihydroxy-l-phenylalanine (l-DOPA) adlayers on the PE surfaces, monitoring the whole adsorption process in situ. A highly charged cationic PE surface exhibits a low adhesion of DOPA molecules, leading to a loose structure, rough surface morphology, and strong solvation effects and, accordingly, this kind of multilayer provides a poor anticorrosion capacity. In comparison, amphiphilic and highly charged cationic PE surfaces are in favor of DOPA adsorption and the formation of compact and smooth multilayers due to cation-π and hydrophobic interactions between DOPA and PEs. Interestingly, one of the multilayers exhibits a remarkable enhancement of inhibition efficiency of about 460-fold compared with that of the bare substrate, which is much higher than that of other anticorrosion coatings reported previously. Our findings reveal the interaction mechanism between DOPA and PE surfaces to achieve the controllable adsorption of biomolecules, providing a promising way to optimize the layer structures to improve the anticorrosion capacity.

To evaluate the fracturing effect and dynamic change process after volume fracturing with vertical wells in low permeability oil reservoirs, an oil-water two-phase flow model and a well model are built. On this basis, an evaluation method of fracturing effect based on production data and fracturing fluid backflow data is established, and the method is used to analyze some field cases. The vicinity area of main fracture after fracturing is divided into different stimulated regions. The permeability and area of different regions are used to characterize the stimulation strength and scale of the fracture network. The conductivity of stimulated region is defined as the product of the permeability and area of the stimulated region. Through parameter sensitivity analysis, it is found that half-length of the fracture and the permeability of the core area mainly affect the flow law near the well, that is, the early stage of production; while matrix permeability mainly affects the flow law at the far end of the fracture. Taking a typical old well in Changqing Oilfield as an example, the fracturing effect and its changes after two rounds of volume fracturing in this well are evaluated. It is found that with the increase of production time after the first volume fracturing, the permeability and conductivity of stimulated area gradually decreased, and the fracturing effect gradually decreased until disappeared; after the second volume fracturing, the permeability and conductivity of stimulated area increased significantly again.

定量评价气举井效率是进行气举方案设计的基础,而目前气举井效率定量评价模型的相关研究较少.通过调研比较2种气举井效率定量评价方法并分析气举井的投入与产出,建立了新的气举井效率定量评价模型.新模型中涉及的参数简单易得,其中的标准参数可以结合油田生产情况进行调整,更能反映不同油田的生产状态,有利于现场应用.利用新模型计算了让纳若尔油田气举井效率,分析了该油田效率影响因素.研究成果丰富完善了气举井效率定量评价方法,对气举井方案设计、优化施工等提供了理论基础.

By using salt dissolution experiment, imbibition experiment and high temperature and high pressure nuclear magnetic resonance（NMR） on-line test, the evaluation methods for salt dissolution of inter salt shale oil-bearing cores were established, and the effects of salt dissolution on spontaneous imbibition and permeability were analyzed. The intensity of salt dissolution is quantitatively evaluated by comparing the signal quantity and distribution characteristics of T2 spectrum（transverse relaxation time） measured at different times. In salt dissolution experiment, salt in the core is gradually dissolved as the injected water is continuously immersed in the core. The spontaneous imbibition experiment of inter-salt shale oil-bearing core can be divided into three stages: strong imbibition and weak salt dissolution, strong salt dissolution promoting imbibition, and weak salt dissolution and weak imbibition. The salt dissolution in spontaneous imbibition is very obvious, and the salt dissolution contributes more than 60% of recovery. The micro-pore structure in different cross sections or different parts of inter-salt shale oil-bearing core isn’t uniform, and the pore volume, porosity and permeability increase after salt dissolution.