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Local Well-posedness for Linearized Degenerate MHD Boundary Layer Equations in Analytic Setting

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Acta Mathematica Sinica,English Series 2019年第8期35卷 1402-1418页

作者： Ya Jun LI wen dong wang School of Mathematical Sciences Dalian University of Technology

In this note we derive MHD boundary layer equations according to viscosity and resistivity coefficients. Especially, when these viscosity and resistivity coefficients are of different orders, it leads to degenerate MH... 详细信息

关键词： MHD equations degenerate boundary layer equations local well-posedness analytic spaces

Relative permeability estimation of oil-water two-phase flow in shale reservoir

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Petroleum Science 2022年第3期19卷 1153-1164页

作者： Yu-Liang Su Ji-Long Xu wen-dong wang Han wang Shi-Yuan Zhan Key Laboratory of Unconventional Oil&Gas Development Ministry of EducationQingdao 266580ShandongChina School of Petroleum Engineering China University of Petroleum(East China)Qingdao 266580ShandongChina

Oil-water two-phase flow is ubiquitous in shale strata due to the existence of connate water and the injection of fracturing *** this work,we propose a relative permeability model based on a modified Hagen-Poiseuille(HP)equation and shale reconstruction *** proposed model can consider the nanoconfined effects(slip length and spatially varying viscosity),oil-water distribution,pore size distribution(PSD),total organic matter content(TOC),and *** results show that the increasing contact angles of organic matters(OM)and inorganic minerals(iOM)increase the relative permeability of both oil and *** the viscosity ratio increases,the relative permeability of oil phase increases while that of water phase decreases,due to the different water-oil *** effective permeability of both oil and water decreases with the increasing ***,the relative permeability of water phase increases while that of oil phase *** increasing number and decreasing deviation angle of micro-fracture increase the effective permeability of oil and ***,microfracture has a minor effect on relative *** model can help understand oil-water twophase flow in shale reservoirs and provide parameter characterization for reservoir numerical simulation.

关键词： Shale Relative permeability Two-phase flow TOC Analytical model

Bifunctional TiO2 Catalysts for Efficient Cr（VI） Photoreduction Under Solar Light Irradiation Without Addition of Acids

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Chinese Journal of Chemical Physics 2012年第2期25卷 214-218,I0004页

作者： Fu-cheng Shi wen-dong wang Wei-xin Huang CAS Key Laboratory of Materials for Energy Conversion Hefei National Laboratory for Physical Sciences at Microscale and Department of Chemical PhysicsUniversity of Science and Technology of ChinaHefei 230026China

Bifunctional TiO2 photocatalysts co-doped with nitrogen and sulfur were prepared by the controlled thermal decomposition of ammonium titanyl sulfate precursor. They have both photocatalytic activity and Brφnsted acidity, and thus are active in the photoreduction of Cr（VI） under solar light irradiation without the addition of acids. The activity is superior to that of Degussa P25 in the acidified suspension at the same pH adjusted by H2SO4.

关键词： Cr(VI) photocatalytic reduction TiO2 Brcnsted acidity Bifunctional catalyst

Analysis of gas transport behavior in organic and inorganic nanopores based on a unified apparent gas permeability model

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Petroleum Science 2020年第1期17卷 168-181页

作者： Qi Zhang wen-dong wang Yilihamu Kade Bo-Tao wang Lei Xiong Key Laboratory of Tectonics and Petroleum Resources China University of GeosciencesWuhan 430074HubeiChina School of Petroleum Engineering China University of Petroleum(East China)Qingdao 266580ShandongChina Institute of Ground Engineering Engineering Technology Research Institute of PetroChina Xinjiang Oilfield CompanyKaramay 834000XinjiangChina Oil Production Plant 5 of PetroChina Changqing Oilfield Company Changqing OilfieldXi’an 710200ShaanxiChina Oil Production Plant 1 of PetroChina Xinjiang Oilfield Company Karamay 834000XinjiangChina

Different from the conventional gas reservoirs,gas transport in nanoporous shales is complicated due to multiple transport mechanisms and reservoir *** this work,we presented a unified apparent gas permeability model for real gas transport in organic and inorganic nanopores,considering real gas effect,organic matter(OM)porosity,Knudsen diffusion,surface diffusion,and stress ***,the effects of monolayer and multilayer adsorption on gas transport are ***,we validated the model by experimental *** influences of pore radius,pore pressure,OM porosity,temperature,and stress dependence on gas transport behavior and their contributions to the total apparent gas permeability(AGP)were *** results show that the adsorption effect causes Kn(OM)>Kn(IM)when the pore pressure is larger than 1 MPa and the pore radius is less than 100 *** ratio of the AGP over the intrinsic permeability decreases with an increase in pore radius or pore *** nanopores with a radius of less than 10 nm,the effects of the OM porosity,surface diffusion coefficient,and temperature on gas transport cannot be ***,the surface diffusion almost dominates in nanopores with a radius less than 2 nm under high OM porosity *** the small-radius and low-pressure conditions,gas transport is governed by the Knudsen diffusion in *** study focuses on revealing gas transport behavior in nanoporous shales.

关键词： Gas transport Apparent gas permeability model Gas adsorption Surface diffusion Stress dependence

A semi-analytical model for coupled flow in stress-sensitive multi-scale shale reservoirs with fractal characteristics

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Petroleum Science 2024年第1期21卷 327-342页

作者： Qian Zhang wen-dong wang Yu-Liang Su Wei Chen Zheng-dong Lei Lei Li Yong-Mao Hao Key Laboratory of Unconventional Oil&Gas Development(China University of Petroleum(East China)) Ministry of EducationQingdao266580ShandongChina School of Petroleum Engineering China University of Petroleum(East China)Qingdao266580ShandongChina Shale Oil Development Branch Changqing Oilfield CompanyPetroChinaQingyang745708GansuChina PetroChina Research Institute of Petroleum Exploration&Development Beijing100083China

A large number of nanopores and complex fracture structures in shale reservoirs results in multi-scale flow of oil. With the development of shale oil reservoirs, the permeability of multi-scale media undergoes changes due to stress sensitivity, which plays a crucial role in controlling pressure propagation and oil flow. This paper proposes a multi-scale coupled flow mathematical model of matrix nanopores, induced fractures, and hydraulic fractures. In this model, the micro-scale effects of shale oil flow in fractal nanopores, fractal induced fracture network, and stress sensitivity of multi-scale media are considered. We solved the model iteratively using Pedrosa transform, semi-analytic Segmented Bessel function, Laplace transform. The results of this model exhibit good agreement with the numerical solution and field production data, confirming the high accuracy of the model. As well, the influence of stress sensitivity on permeability, pressure and production is analyzed. It is shown that the permeability and production decrease significantly when induced fractures are weakly supported. Closed induced fractures can inhibit interporosity flow in the stimulated reservoir volume (SRV). It has been shown in sensitivity analysis that hydraulic fractures are beneficial to early production, and induced fractures in SRV are beneficial to middle production. The model can characterize multi-scale flow characteristics of shale oil, providing theoretical guidance for rapid productivity evaluation.

关键词： Multi-scale coupled flow Stress sensitivity Shale oil Micro-scale effect Fractal theory

Evolutionary-assisted reinforcement learning for reservoir real-time production optimization under uncertainty

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Petroleum Science 2023年第1期20卷 261-276页

作者： Zhong-Zheng wang Kai Zhang Guo-dong Chen Jin-Ding Zhang wen-dong wang Hao-Chen wang Li-Ming Zhang Xia Yan Jun Yao School of Petroleum Engineering China University of PetroleumQingdao266580ShandongChina Qingdao University of Technology Qingdao266520ShandongChina The University of Hong Kong 999077Hong KongChina

Production optimization has gained increasing attention from the smart oilfield community because it can increase economic benefits and oil recovery *** existing methods could produce high-optimality results,they cannot be applied to real-time optimization for large-scale reservoirs due to high computational *** addition,most methods generally assume that the reservoir model is deterministic and ignore the uncertainty of the subsurface environment,making the obtained scheme unreliable for practical *** this work,an efficient and robust method,namely evolutionaryassisted reinforcement learning(EARL),is proposed to achieve real-time production optimization under ***,the production optimization problem is modeled as a Markov decision process in which a reinforcement learning agent interacts with the reservoir simulator to train a control policy that maximizes the specified *** deal with the problems of brittle convergence properties and lack of efficient exploration strategies of reinforcement learning approaches,a population-based evolutionary algorithm is introduced to assist the training of agents,which provides diverse exploration experiences and promotes stability and robustness due to its inherent *** with prior methods that only optimize a solution for a particular scenario,the proposed approach trains a policy that can adapt to uncertain environments and make real-time decisions to cope with unknown *** trained policy,represented by a deep convolutional neural network,can adaptively adjust the well controls based on different reservoir *** results on two reservoir models show that the proposed approach not only outperforms the RL and EA methods in terms of optimization efficiency but also has strong robustness and real-time decision capacity.

关键词： Production optimization Deep reinforcement learning Evolutionary algorithm Real-time optimization Optimization under uncertainty

Performance-based fractal fracture model for complex fracture network simulation

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Petroleum Science 2018年第1期15卷 126-134页

作者： wen-dong wang Yu-Liang Su Qi Zhang Gang Xiang Shi-Ming Cui School of Petroleum Engineering China University of Petroleum (East China) Qingdao 266580 Shandong China CCDC Downhole Service Company Chengdu 610213 Sichuan China China National Petroleum Corporation Jilin Oil FieldXinmu Oil Production Plant Jilin 138000 China

The paper presents a novel hydraulic fracturing model for the characterization and simulation of the complex fracture network in shale gas reservoirs. We go beyond the existing method that uses planar or orthogonal conjugate fractures for representing the ＇＇complexity＇＇ of the network. Bifurcation of fractures is performed utilizing the Lindenmayer system based on fractal geometry to describe the fracture propagation pattern, density and network connectivity. Four controlling parameters are proposed to describe the details of complex fractures and stimulated reservoir volume（SRV）. The results show that due to the multilevel feature of fractal fractures, the model could provide a simple method for contributing reservoir volume calibration. The primary-and second-stage fracture networks across the overall SRV are the main contributions to the production, while the induced fracture network just contributes another 20% in the late producing period. We also conduct simulation with respect to different refracturing cases and find that increasing the complexity of the fracture network provides better performance than only enhancing the fracture conductivity.

关键词： Fractal geometry Fractal fracture model Complex fracture network characterization Contributing reservoirvolume Refracturing

Nitrogen-doped graphene/carbon nanohorns composite as a high-performance supercapacitor electrode

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Journal of Materials Science & Technology 2017年第11期33卷 1339-1345页

作者： Xiao-Qiang Lin wen-dong wang Qiu-Feng Lu Yan-Qiao Jin Qilang Lin Rui Liu College of Materials Science and Engineering Fuzhou University Fuzhou 350116 China Key Laboratory of Eco-materials Advanced Technology Fuzhou University Fuzhou 350116 China Ministry of Education Key Laboratory of Advanced Civil Engineering Material School of Materials Science and Engineering and Institute for AdvancedStudy Tongji University Shanghai 201804 China

Nitrogen-doped graphene/carbon nanohorns composite（NGLC） was prepared by one-step co-pyrolysis of graphene oxide, carbon nanohorns（CNHs）, urea, and lignosulfonate. CNHs as spacers were inserted into graphene nanosheets. The introduction of CNHs and the loosened nano-structure of NGLC make it achieve a high specific capacitance of 363 Fg^（-1） at a discharge current density of 1 A g^（-1）, and NGLC exhibits an ultrahigh stability of 93.5% capacitance retention ratio after 5000 cycles. The outstanding comprehensive electrochemical performance of NGLC could meet the need of the future acted as an efficient supercapacitor electrode material.

关键词： Nitrogen-doped graphene Carbon nanohorns Spacer Supercapacitor High-performance

Clay-Supported Molybdenum-Based Catalysts for Higher Alcohol Synthesis from Syngas

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Chinese Journal of Chemical Physics 2015年第5期28卷 -页

作者： Gai-mei Wu Ji-long Zhou Mei-mei Lv Wei Xie Song Sun Chen Gao wen-dong wang Department of Chemical Physics University of Science and Technology of China Hefei 230026China National Synchrotron Radiation Laboratory University of Science and Technology of China Hefei 230029 China

A kind of clay-supported K-Co-Mo catalyst was prepared by a sol-gel method combined with incipient wetness impregnation. The catalyst structure was characterized by X-ray diffraction, N2 adsorption-desorption, H2 temperature-programmed reduction, and X-ray photoelectron spectroscopy techniques and its catalytic performance for higher alcohol synthesis from syngas was investigated. The active components has a high dispersion on the clay support surface. The increase of the Mo loading promoted reduction of Mo6+ but had no significant influence on the reduction of Mo4+ and Co2+ species. After reduction, a kind of lower state Moδ+ (1<δ<4) species was observed on the surface. Compared with the unsupported catalyst, the clay supported K-Co-Mo catalysts showed much higher catalytic performance for alcohol formation. The reason can be explained that the supported catalyst have a high active surface area and the mesoporous structure prolonged the residence time of intermediates for alcohol formation to some extent, which promoted the formation of higher alcohols. The high activity of the catalyst reduced at 773 K may be attributed to the high content of Moδ+ (1<δ<4) species on the surface, which was regarded as the active site for the adsorption of nondissociative CO and responsible for the alcohol formation.

关键词： Higher alcohol synthesis Clay support K-Co-Mo catalyst Syngas