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Effect of Ga addition on the magnetic properties and microstructure of nanocrystalline Nd_(12.3)Fe_(81.7)B_(6.0) ribbons

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Rare Metals 2011年第5期30卷 447-452页

作者： BAO Xiaoqian guo Xiaoyan guo jianchun GAO Xuexu State Key Laboratory for Advanced Metals and Materials University of Science and Technology Beijing Beijing 100083 China Shandong Jinma Industrial Group Co. Ltd. Rizhao 276826 China

Nd 12.3 Fe 81.7 x Ga x B 6.0 （x = 0-1.8） ribbons were prepared by melt spinning at 22 m/s and subsequent annealing treatment. The influences of Ga addition and annealing conditions on the magnetic properties and microstructure of the nanocrystalline alloys were systematically investigated. After being annealed at 620℃ for 20 min, the J r and H ci increased from 0.85 T and 582.6 kA/m for Ga-free sample to 0.97 T and 734.6 kA/m for the x = 0.9 sample, respectively. The （BH） max for the x = 0.9 sample increased by about 40% from 96.3 to 135.5 kJ/m 3 compared with that of the Ga-free one. The significant improvement of magnetic properties originated from the refinement of grains in the samples by introducing Ga, which led to a stronger exchange coupling between the neighboring grains in comparison with that in Ga-free samples. The microstructure and magnetic properties of the samples depended strongly on annealing parameters, while the sensitivity of micro-structure to annealing conditions could be significantly suppressed by the addition of Ga element.

关键词： nanocrystalline alloys exchange coupling microstructure magnetic properties gallium

Influence of pore pressure on tensile fracture growth in rocks： a new explanation based on numerical testing

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Frontiers of Earth Science 2015年第3期9卷 412-426页

作者： Shou MA jianchun guo Lianchong LI Leslie George THAM Yingjie XIA Chun'an TANG State Key Laboratory of Oil and Gas Geology and Exploitation Southwest Petroleum University Chengdu 610500 China SINOPEC Shengli Oilfield Company Dongying 257000 China School of Civil Engineering Dalian University of Technology Dalian 116024 China Department of Civil Engineering The University of Hong Kong Hong Kong China

The diffusion of pore fluid pressures may create both spatial and temporal effective stress gradients that influence or control the development and evolution of fractures within rock masses. To better understand the controls on fracturing behavior, numerical simulations are performed using a progressive fracture modeling approach that shares many of the same natural kinematic features in rocks, such as fracture growth, nucleation, and termination. First, the pinch-off breaking test is numerically performed to investigate the tensile failure of a rock specimen in a uniform pore pressure field. In this numerical simulation, both mechanical and hydrological properties of a suite of rocks are measured under simulated laboratory conditions. The complete tensional failure process of the rock specimen under pore pressure was reproduced. Second, a double-notched specimen is numerically extended to investigate how the water flow direction or pore pressure gradient influences the fracture growth. An exhaustive sensitivity study is conducted that examines the effects of varying both hydrological and mechanical boundary conditions. The simulation results indicate that local fluid pressure gradients strongly influence the state of stress in the solids and, thereby, fracture growth. Fracture and strength behavior is influenced not only by the pore pressure magnitude on a local scale around the fracture tip, but also by the orientation and distribution of pore pressure gradients on a global scale. Increasing the fracture growth rate increases the local model permeability and decreases the sample strength. The results of this study may provide useful information concerning the degree of hydrological and mechanical coupling action under geologic conditions.

关键词： pore pressure effective stress heterogeneous numerical simulation fracture growth rock

hale gas reservoir modeling and production evaluation considering complex gas transport mechanisms and dispersed distribution of kerogen

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Petroleum Science 2021年第1期18卷 195-218页

作者： Jie Zeng Jishan Liu Wai Li Yee-Kwong Leong Derek Elsworth jianchun guo School of Engineering The University of Western Australia35 Stirling HighwayPerthWA 6009Australia Department of Energy and Mineral Engineering G3 Center and Energy InstituteThe Pennsylvania State UniversityUniversity ParkPA 16802USA State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation Southwest Petroleum UniversityChengdu 610500China

Stimulated shale reservoirs consist of kerogen,inorganic matter,secondary and hydraulic *** dispersed distribution of kerogen within matrices and complex gas flow mechanisms make production evaluation *** we establish an analytical method that addresses kerogen-inorganic matter gas transfer,dispersed kerogen distribution,and complex gas flow mechanisms to facilitate evaluating gas *** matrix element is defined as a kerogen core with an exterior inorganic *** most previous models,we merely use boundary conditions to describe kerogen-inorganic matter gas transfer without the instantaneous kerogen gas source *** is closer to real inter-porosity flow conditions between kerogen and inorganic *** diffusion,surface diffusion,adsorption/desorption,and slip corrected flow are involved in matrix gas ***-fracture coupling is realized by using a seven-region linear flow *** model is verified against a published model and field *** reveal that inorganic matrices serve as a major gas source especially at early *** provides limited contributions to production even under a pseudo-steady *** properties’influence starts from the late matrix-fracture inter-porosity flow regime,while inorganic matter properties control almost all flow regimes except the early-mid time fracture linear flow *** contribution of different linear flow regions is also documented.

关键词： Analytical solution Shale gas reservoir Well performance Kerogen and inorganic matter

An optimization model for conductivity of hydraulic fracture networks in the Longmaxi shale,Sichuan basin,Southwest China

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Energy Geoscience 2020年第1期1卷 47-54页

作者： Zhihong Zhao Kaidi Wu Yu Fan jianchun guo Bo Zeng Wenhan Yue State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation Southwest Petroleum UniversityChenduSichuanChina Shale Gas Research Institute PetroChina Southwest Oil and Gas Field CompanyChenduSichuanChina

Shale gas is an important unconventional *** economic recovery of shale gas is only possible when a fracture network with sufficient conductivity is created by hydraulic fracturing,that,if effectively propped,connects fracturing fractures and natural *** on the Longmaxi shale in the Sichuan Basin,Southwest China,we built an optimization model for conductivity of multi-grade fractures based on equivalent seepage *** then experimentally analyzed the conductivity of self-propped and sand-propped fractures,and optimized the propping patterns of multi-grade hydraulic fractures in shale gas *** concluded that the propping effectiveness of fracture networks could be improved by using low concentrations of small-sized sands and by focusing on creating a large number of self-propped *** applying this understanding to the optimization of fracturing designs for the Longmaxi shale,we successfully created networks of well-propped fractures.

关键词： Fracture network Conductivity optimization Propped fracture Self-propped fracture Shale gas

Experimental study on proppant-carrying migration and settlement of slickwater in narrow plate fractures based on PIV/PTV

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Petroleum 2024年第3期10卷 494-510页

作者： Tao Zhang Tang Tang jianchun guo Hangyu Zhou Yuxuan Liu Yifan Zhang Xianjin Zeng State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation Southwest Petroleum UniversityChengdu610500China Hainan Branch of CNOOC Limited HaikouHainan570300China

Hydraulic fracturing is the primary method used for oilfield stimulation,and the migration and settlement pattern of proppant plays a crucial role in the formation of high conductivity propping fractures in the *** study summarizes two growth modes of sand dune:the‘overall longitudinal growth’mode and the‘push growth along fracture length direction’*** investigate these modes,a twophase velocity test is conducted using PIV,and the exposure difference is utilized to separate the tracer and track the single-phase *** analyzing the slickwater flow field and proppant velocity field,the micro-motion mechanism behind the two dune growth modes is quantitatively *** results indicate that mode 1 growth of the sand dune occurs when a pump with a large mesh number,high polymer viscosity,and large displacement is *** the other hand,mode 2 growth is observed when a pump with a small mesh number,low polymer viscosity,and small displacement is *** is important to note that there is no clear boundary for the migration and sedimentation mode of proppant,as they can transition into each other under certain *** modes only exist during specific stages of sand dune *** the case of the‘backflow’pattern,the settlement of proppant is primarily influenced by the vortex structure of ***,in the‘direct’pattern,the proppant is propelled forward by the drag of the fluid and settles due to its own *** the proppant placement reaches equilibrium,the direction of proppant velocity follows a normal distribution within 0°.This approach establishes a connection between the overall placement of the sand dune and the microscopic movement of the proppant and *** construction parameters during fracturing construction can enhance the effectiveness of distal proppant placement in fractures.

关键词： Slickwater fracturing Proppant transport Multiphase flow PIV/PTV

Evaluation on the anisotropic brittleness index of shale rock using geophysical logging

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Petroleum 2023年第4期9卷 545-557页

作者： Junchuan Gui jianchun guo Yu Sang Yaxi Chen Tianshou Ma P.G.Ranjith Research Institute of Shale Gas PetroChina Southwest Oil and Gasfield CompanyChengdu610051China State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation Southwest Petroleum UniversityChengdu610500China Shunan Gas Mine PetroChina Southwest Oil and Gas Field CompanyLuzhou646000China Downhole Service Company CNPC Chuanqing Drilling Engineering Company LimitedChengdu610501China Deep Earth Energy Laboratory Department of Civil EngineeringMonash UniversityMelbourne3800Australia

The brittleness index plays a significant role in the hydraulic fracturing design and wellbore stability analysis of shale *** brittleness indices have been proposed to characterize the brittleness of shale rocks,but almost all of them ignored the anisotropy of the brittleness ***,uniaxial compression testing integrated with geophysical logging was used to provide insights into the anisotropy of the brittleness index for Longmaxi shale,the presented method was utilized to assess brittleness index of Longmaxi shale formation for the interval of 3155e3175 m in CW-1 *** results indicated that the brittleness index of Longmaxi shale showed a distinct anisotropy,and it achieved the minimum value at β=45°-60°.As the bedding angle increased,the observed brittleness index(BI_(2_β))decreased firstly and increased then,it achieved the lowest value at β=40°-60°,and it is consistent with the uniaxial compression testing *** to the isotropic brittleness index(β=0°),the deviation of the anisotropic brittleness index ranged from 10%to 66.7%,in other words,the anisotropy of brittleness index cannot be ignored for Longmaxi *** matter content is one of the main intrinsic causes of shale anisotropy,and the anisotropy degree of the brittleness index generally increases with the increase in organic matter *** present work is valuable for the assessment of anisotropic brittleness for hydraulic fracturing design and wellbore stability analysis.

关键词： Shale rock Brittleness Brittleness index Anisotropy Transverse isotropy Geophysical logging

Comparison of the clinical features and therapeutics of COVID-19 in cardio-cerebrovascular disease(CCVD)and non-CCVD patients

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Frontiers of Medicine 2021年第4期15卷 629-637页

作者： Yu Wang Lan Li Yuanjiang Pan Yu He Zuhua Chen Yunhao Xun Yuhan Xu Yilei guo Jiehong Yang jianchun guo Haitong Wan Institute of Cardio-cerebrovascular Disease Zhejiang Chinese Medical UniversityHangzhou 310053China Department of Chemistry Zhejiang UniversityHangzhou 310027China College of Pharmaceutical Science Zhejiang Chinese Medical UniversityHangzhou 310053China School of Basic Medical Sciences and Public Health Zhejiang Chinese Medical UniversityHangzhou 310053China Integrated TCM&Western Medicine Department Xixi Hospital of HangzhouHangzhou 310023China

Cardio-cerebrovascular disease(CCVD)is a major comorbidity of coronavirus disease 2019(COVID-19).However,the clinical characteristics and outcomes remain *** this study,102 cases of COVID-19 from January 22,2020 to March 26,2020 in Xixi Hospital of Hangzhou were *** cases had pre-existing *** showed that compared with non-CCVD patients,those with CCVD are more likely to develop severe disease(15%versus 1%),and the proportion of pneumonia severity index grade IV was significantly higher(25%versus 3.6%).Computed tomography images demonstrated that the proportion of multiple lobe lesion involvement was significantly higher in the CCVD group than in the non-CCVD group(90%versus 63.4%).Compared with non-CCVD group,the levels of C-reactive protein,fibrinogen,D-dimer,and serum amyloid-A were higher,whereas the total protein and arterial partial Pa02 were lower in the CCVD *** no statistical difference was observed in the outcomes between groups,CCVD patients received more intensive comprehensive treatment to improve COVID-19 symptoms compared with non-CCVD *** Chinese and Western medicine treatments have certain advantages in controlling the severe conversion rate and mortality of *** addition,given that COVID-19 patients are usually related to coagulation disorders and thrombosis risk,the application of Chinese medicine in promoting blood circulation and removing stasis should be strengthened.

关键词： COVID-19 cardio-cerebrovascular disease traditional Chinese medicine clinical features clinical therapeutics

Effect of fracture fluid flowback on shale microfractures using CT scanning

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第2期16卷 426-436页

作者： Jiale He Zhihong Zhao Yiran Geng Yuping Chen jianchun guo Cong Lu Shouyi Wang Xueliang Han Jun Zhang State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation Southwest Petroleum UniversityChengdu610500China Key Laboratory of Thermo-Fluid Science and Engineering of Ministry of Education School of Energy and Power EngineeringXi’an Jiaotong UniversityXi’an710049China Drilling Test Engineering Department of Longdong Oil and Gas Development Company Changqing OilfieldPetroChina Company LimitedQingyang745000China Tight Oil and Gas Exploration and Development Project Department PetroChina Southwest Oil and Gas Field CompanyChengdu610056China No.11 Oil Production Plant Changqing Oilfield CompanyPetroChina Company LimitedQingyang745000China

The field data of shale fracturing demonstrate that the flowback performance of fracturing fluid is different from that of conventional reservoirs,where the flowback rate of shale fracturing fluid is lower than that of conventional *** the early stage of flowback,there is no single-phase flow of the liquid phase in shale,but rather a gas-water two-phase flow,such that the single-phase flow model for tight oil and gas reservoirs is not *** this study,pores and microfractures are extracted based on the experimental results of computed tomography(CT)scanning,and a spatial model of microfractures is ***,the influence of rough microfracture surfaces on the flow is corrected using the modified cubic law,which was modified by introducing the average deviation of the microfracture height as a roughness factor to consider the influence of microfracture surface *** flow in the fracture network is simulated using the modified cubic law and the lattice Boltzmann method(LBM).The results obtained demonstrate that most of the fracturing fluid is retained in the shale microfractures,which explains the low fracturing fluid flowback rate in shale hydraulic fracturing.

关键词： Shale Flowback of fracturing fluid Microfracture Lattice Boltzmann method(LBM)

Optimization of refracturing timing for horizontal wells in tight oil reservoirs: A case study of Cretaceous Qingshankou Formation, Songliao Basin, NE China

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Petroleum Exploration and Development 2019年第1期46卷 153-162页

作者： guo jianchun TAO Liang ZENG Fanhui State Key Laboratory of Oil & Gas Reservoir Geology and Exploitation in Southwest Petroleum University

Tight oil reservoirs in Songliao Basin were taken as subjects and a novel idealized refracturing well concept was proposed by considering the special parameters of volume fracturing horizontal wells, the refracturing potential of candidate wells were graded and prioritized, and a production prediction model of refracturing considering the stress sensitivity was established using numerical simulation method to sort out the optimal refracturing method and timing. The simulations show that: with the same perforation clusters, the order of fracturing technologies with contribution to productivity from big to small is refracturing between existent fractured sections, orientation diversion inside fractures, extended refracturing, refracturing of existent fractures; and the later the refracturing timing, the shorter the effective time. Based on this, the prediction model of breakdown pressure considering the variation of formation pressure was used to find out the variation pattern of breakdown pressure of different positions at different production time. Through the classification of the breakdown pressure, the times of temporary plugging and diverting and the amount of temporary plugging agent were determined under the optimal refracturing timing. Daily oil production per well increased from 2.3 t/d to 16.5 t/d in the field test. The research results provide important reference for refracturing optimization design of similar tight oil reservoirs.

关键词： Songliao Basin tight oil reservoirs refracturing volume fracturing breakdown pressure temporary plugging and diverting