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Multiple damage zones around hydraulic fractures generated by high-frequency pulsating hydraulic fracturing

Petroleum Science 2024年第4期21卷 2688-2702页

作者： Yan Peng Sheng-Jie Wei guang-qing zhang Da-Wei Zhou Chuang-Chao Xu School of Petroleum Engineering China University of Petroleum18 Fuxue RoadChangpingBeijing102249China PetroChina Changqing Oilfield Company Xi'an710018ShaanxiChina

Pulsating hydraulic fracturing(PHF)is a promising fracturing method and can generate a dynamic periodic *** periodic pressure can induce fatigue failure of rocks and decrease initiation pressure of *** the frequency of periodic pressure exceeds 10 Hz,the distribution of pressure along the main fracture will be heterogeneous,which is much different from the one induced by the common fracturing *** this study,the impact of this special spatial feature of pressure on hydraulic fracture is mainly investigated.A coupled numerical simulation model is first proposed and verified through experimental and theoretical *** mechanism of secondary fracture initiation around the main fracture is then *** addition,sensitivity studies are conducted to find out the application potential of this new *** results show that(1)this coupled numerical simulation model is *** comparison with experimental and theoretical data,the average error of this coupled model is less than 1.01%.(2)Even if a reservoir has no natural fracture,this heterogeneous distribution pressure can also cause many secondary fractures around the main fracture.(3)The mechanism of secondary fracture initiation is that this heterogeneous distribution pressure causes tensile stress at many locations along the main fracture.(4)Through adjusting the stimulation parameters,the stimulation efficiency can be *** average and amplitude of pressure can increase possibility of secondary fracture *** frequency of this periodic pressure can increase number of secondary *** 6 secondary fractures along a 100 m-length main fracture can be generated.(5)The influence magnitudes of stimulation parameters are larger than ones of geomechanical properties,therefore,this new fracturing method has a wide application potential.

关键词： Tight reservoir Reservoir stimulation Numerical simulation Secondary fracture Fracture initiation

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Laboratory investigation on hydraulic fracture propagation in sandstone-mudstone-shale layers

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Petroleum Science 2022年第4期19卷 1664-1673页

作者： Jiang-Chuan He Kuang-Sheng zhang Han-Bin Liu Mei-Rong Tang Xue-Lin Zheng guang-qing zhang PetroChina Changqing Oilfield Company Xi′an710018ShaanxiChina College of Petroleum Engineering China University of Petroleum(Beijing)Beijing102249China State Key Laboratory of Petroleum Resources and Prospecting China University of Petroleum(Beijing)Beijing102249China

During the stimulating unconventional reservoirs, the vertical propagation of hydraulic fractures is crucial for enlarging the stimulated reservoir volume, especially in multi-layers of sandstone, mudstone and shale(sand-mud-shale). To investigate the effects of lithological interface and fracturing fluid viscosity on the fracture propagation vertically in the multi-layers, hydraulic fracturing experiments in laboratory were performed on the outcrop samples of 30 cm × 30 cm × 30 cm collected from Yanchang Formation in Ordos Basin. The results show that hydraulic fractures are multi-branched and zig-zagged when they initiate in shale, simple when they commence in sandstone or mudstone. Hydraulic fractures created with low-viscosity fracturing fluid can only cross sandstone from mudstone, but those induced by high-viscosity fracturing fluid can cross the sand-mud-shale layers. Furthermore, the high-viscosity fracturing fluid reduces the fractures complexity in shale, facilitating vertical fracture propagation. The injection pressure fluctuates slightly as the hydraulic fracture extends from shale to sandstone or mudstone, otherwise it fluctuates significantly. From the laboratory investigation, a hydraulic fracturing scheme for Chang 7 Member was proposed, with its feasibility proved in field tests.

关键词： Sandstone-mudstone-shale Multi-layers Hydraulic fracturing experiments Lithological interface

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Effects of supercritical CO_(2) on viscoelastic properties of shales

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Petroleum Science 2022年第5期19卷 2199-2209页

作者： Da-Wei Zhou guang-qing zhang Zhong-Wei Huang Shi-Yuan Li Zong-Yang Fan College of Petroleum Engineering China University of Petroleum in BeijingBeijing102249China State Key Laboratory of Petroleum Resources and Engineering China University of Petroleum in BeijingBeijing102249China

Laboratory uniaxial compression creep tests,with differential stress of 30 MPa hold for 3 h,were performed on Chang-7,Longmaxi(LMX)and Barnett shales to study the influence of SC-CO_(2)on short-term viscoelastic *** this end,the wet shale samples were treated with SC-CO_(2)with a pressure of30 MPa and a temperature of 110℃for 14 *** analyzed the creep data using the fractional Maxwell *** investigate microscopic structural alterations,the surface morphology of the same location,before and after SC-CO_(2)-water exposure,was examined by SEM *** with dry shales,dynamic and static elastic moduli decreased by up to 25.02%and 55.83%,respectively,but the creep deformation increased by 200%for LMX and Chang-7 shales,and 500%for the Barnett shale treated by SC-CO_(2).Compared to dry sample,there is an increase in calculated fractional orders of 0.02,0.07,0.22 for SC-CO_(2)treated samples,indicating that SC-CO_(2)treatment is likely to enhance shale *** investigation confirmed physicochemical mechanisms responsible for the observed elastic damage and creep enhancement,including mineral dissolution and swelling caused by SC-CO_(2).This work would further improve our current understanding of the time-dependent deformation of shale under chemicalmechanical coupling effects during CO_(2)capture utilization and storage.

关键词： Shale creep Viscoelastic deformation SC-CO_(2)exposure Physicochemical mechanisms

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Prognostic value of circulating tumor cells in esophageal cancer

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World Journal of Gastroenterology 2017年第7期23卷 1310-1318页

作者： Hai-Tao Xu Jing Miao Jian-Wei Liu Lian-Guo zhang qing-guang zhang Department of Thoracic Surgery Affiliated Hospital of Binzhou Medical University Department of Neonatal Intensive Care Unit Binzhou People’s Hospital

AIM To perform a meta-analysis of the related studies to assess whether circulating tumor cells(CTCs) can be used as a prognostic marker of esophageal *** Pub Med, Embase, Cochrane Library and references in relevant studies were searched to assess the prognostic relevance of CTCs in patients with esophageal cancer. The primary outcome assessed was overall survival(OS). The meta-analysis was performed using the random effects model, with hazard ratio(HR), risk ratio(RR) and 95% confidence intervals(95%CIs) as effect *** Nine eligible studies were included involving a total of 911 esophageal cancer patients. Overall analyses revealed that CTCs-positivity predicted disease progression(HR = 2.77, 95%CI: 1.75-4.40, P < 0.0001) and reduced OS(HR = 2.67, 95%CI: 1.99-3.58, P < 0.00001). Further subgroup analyses demonstrated that CTCs-positive patients also had poor OS in different subsets. Moreover, CTCs-positivity was also significantly associated with TNM stage(RR = 1.48, 95%CI: 1.07-2.06, P = 0.02) and T stage(RR = 1.44, 95%CI: 1.13-1.84, P = 0.003) in esophageal *** Detection of CTCs at baseline indicates poor prognosis in patients with esophageal cancer. However, this finding relies on data from observational studies and is potentially subject to selection bias. Prospective trials are warranted.

关键词： Circulating tumor cells Esophageal cancer Prognosis Meta-analysis

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Predictors and clinical significance of the positive cone margin in cervical intraepithelial neoplasia III patients

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Chinese Medical Journal 2009年第4期122卷 367-372页

作者： SUN Xiao-guang MA Shui-qing zhang Jin-xia WU Ming Department of Obstetrics and Gynecology Peking Union MedicalCollege Hospital Chinese Academy of Medical Sciences & PekingUnion Medical College Beijing 100730 China

Background Conization is being widely accepted for diagnosis and treatment of cervical intraepithelial neoplasia （CIN）. There is controversy as to which factors are most predictive of a positive cone margin and the clinical significance of it. We conducted this study to identify the predictive factors and to evaluate the clinical significance of a positive cone margin in CIN III patients.Methods A retrospective review was conducted of 207 patients who had undergone conization due to CIN III from January 2003 to December 2005 at Peking Union Medical College Hospital. Of these, 67 had a subsequent hysterectomy Univariate and multivariate analysis were utilized to define the predictive factors for a positive cone margin, and to compare the pathologic results of conization with subsequent hysterectomy.Results One hundred and fifty-one （72.9%） were margin free of CIN I or worse, 37 （17.9%） had CIN lesions close to the margin and 19 （9.2%） had margin involvement. A total of 56 cases （27.1%） had positive cone margins （defined as the presence of CIN at or close to the edge of a cone specimen）. Univariate analysis showed that the parity, cytological grade multi-quadrants of CIN III by punch biopsy, gland involvement, as well as the depth of conization were significant factors correlated with a positive cone margin （P 〈0.05）. However the age, gravidity, grade of dysplasia in punch biopsy, as well as the cone methods were not significantly correlated （P 〉0.05）. Multivariate analysis revealed that the cytological grade （OR=1.92）, depth of conization （OR=2.03）, parity （OR=3.02） and multi-quadrants of CIN III （OR=4.60） were significant predictors with increased risk for positive margin. The frequency of residual CIN I or worse in hysterectomy specimens was found to be 55.6% （20/36） in patients who were margin free, 71.4% （15/21） in patients with CIN occurring close to margin, and 80.0% （8/10） in patients with margin involvement. The frequency of residual CIN III or worse was

关键词： conization cervical intraepithelial neoplasia factor analysis

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Selenate oxyanion-intercalated NiFeOOH for stable water oxidation via lattice oxygen oxidation mechanism

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Journal of Energy Chemistry 2025年第2期101卷 676-684页

作者： Yijie zhang Weiyi zhang Xiaowen zhang Jinping Li guang Liu Shanxi Key Laboratory of Gas Energy Efficient and Clean Utilization College of Chemical Engineering and Technology Taiyuan University of Technology Shanxi Research Institute of Huai Rou Laboratory

Transition metal-based compounds can serve as pre-catalysts to obtain genuine oxygen evolution reaction（OER） electrocatalysts in the form of oxyhydroxides through electrochemical ***,the role and existence form of leached oxygen anions are still ***,we selected iron selenite-wrapped hydrated nickel molybdate（denoted as NiMoO/FeSeO） as a pre-catalyst to study the oxyanion *** is surprising to find that SeO2-exists in the catalyst in the form of intercalation,which is different from previous studies that suggest that anions are doped with residual elements after electrochemical activation,or adsorbed on the catalyst *** experiment and theoretical calculations show that the existence of SeO42-intercalation effectively adjusts the electronic structure of NiFeOOH,promotes intramolecular electron transfer and O-O release,and thus lowers the reaction energy *** expected,the synthesized NiFeOOH-SeO only needs 202 and 285 mV to attain 100 and 1000 mA cm-2in 1 M ***,the anion exchange membrane water electrolyzer（AEMWE） consisting of NiFeOOHSeO anode and Pt/C cathode can reach 1 A cm-2at 1.70 V and no significant attenuation within 300 *** findings provide insights into the mechanism,by which the intercalated oxyanions enhance the OER performance of NiFeOOH,thereby facilitating large-scale hydrogen production through AEMWE.

关键词： Anion exchange membrane electrolyzer Industrial current densities Lattice oxygen oxidation Oxyanion intercalation Water splitting

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Some fundamental issues in buoyancy-driven flows with implications for geophysical and astrophysical systems

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Acta Mechanica Sinica 2025年第1期41卷 1-21页

作者： Ke-qing Xia Kai Leong Chong guang-Yu Ding Lu zhang Center for Complex Flows and Soft Matter Research Southern University of Science and TechnologyShenzhen 518055China Department of Mechanics and Aerospace Engineering Southern University of Science and TechnologyShenzhen 518055China Shanghai Key Laboratory of Mechanics in Energy Engineering Shanghai Institute of Applied Mathematics and MechanicsSchool of Mechanics and Engineering ScienceShanghai UniversityShanghai 200072China

Buoyancy-driven flows are prevalent in a wide range of geophysical and astrophysical systems. In this review, we focus on threepivotal effects that significantly influence the dynamics and transport properties of buoyancy-driven flows and may have impli-cations for natural systems. These effects pertain to the role of boundary conditions, the impact of rotation, and the effect offinite size. Boundary conditions represent how the fluid flow interacts with different kinds of surfaces. Rotation, as the Earth’srotation in geophysical systems or the whirling of astrophysical systems, introduces Coriolis and centrifugal forces, leading tothe profound vortical structure and distinct transport property. Finite size, representing geometrical constraints, influences thebehavior of buoyancy-driven flows across varying geometrical settings. This review aims to provide a holistic understanding ofthe intricate interplay of these factors, offering insights into the complex natural phenomena from the perspectives of the threeeffects.

关键词： Buoyancy-driven flows Geophysical turbulence Rayleigh-B´enard convection

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Correlation between grain size,mechanical properties and deformed microstructure of Fe-20Mn-6Al-0.6C-0.15Si low-density steel

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Journal of Iron and Steel Research International 2025年第1期32卷 282-292页

作者： Qi zhang guang-hui Chen Zheng-liang Xue Zheng-kun Chen guang Xu State Key Laboratory of Refractories and Metallurgy Wuhan University of Science and TechnologyWuhan430081HubeiChina Key Laboratory for Ferrous Metallurgy and Resources Utilization of Ministry of Education Wuhan University of Science and TechnologyWuhan430081HubeiChina Red Eagle Novel Refractory Materials Research Institute Zhejiang Red Eagle Group Co.Ltd.Huzhou313000ZhejiangChina

The effects of austenite grain size on the deformed microstructure and mechanical properties of an Fe-20Mn-6Al-0.6C-0.15Si(wt.%)low-density steel were *** microstructure of the experimental steel after solution treatment was single austenitic *** austenite grain size increased with solution temperature and time.A model was established to show the relationship between temperature,time and austenite grain size for the experimental *** addition,as the solution temperature increased,the strength decreased,while the elongation first increased and then *** decrease in elongation after solution treatment at 1100℃ for 90 min is contributed to the over-coarse austenite ***,after solution treatment at 900℃ for 90 min,the strength-elongation product reached the highest value of 44.4 GPa%.As the austenite grain size increased,the intensity of//tensile direction fiber *** was accompanied by a decrease in dislocation density,resulting in a lower fraction of low-angle grain boundaries and a lower work hardening ***,the austenite grain size has a critical influence on the mechanical properties of the low-density *** grains lead to a lower yield strength due to the Hall-Petch effect and a lower tensile strength because of lower dislocation strengthening.

关键词： Austenitic low-density steel Solution treatment Grain size Mechanical property Deformed microstructure

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Raman amplification of Stokes pulse in ultra-small silicon-on-insulator optical waveguide

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Optoelectronics Letters 2008年第1期4卷 12-14页

作者： WU Jian-wei, LUO Feng-guang, zhang qing-tang, and HUANG Yong-jun Institute of Optoelectronics Science and Engineering and Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074, China Institute of Optoelectronics Science and Engineering and Wuhan National Laboratory for Optoelectronics Huazhong University of Science and Technology Wuhan China

The stimulated Raman amplification of picosecond Stokes pulse is numerically investigated in ultra-small silicon-on- insulator optical waveguide. Numerical results show that we obtain the gain of up to 30-dB for weak Stokes pulse in the co- propagation configuration for 10 mm Jength waveguide using high intensity pump optical pulse. The peak gain, pulse width, rise time, and fall time of Stokes pulse will experience the variation course of decaying then increasing with increas- ing waveguide length. The time delay of output Stokes pulse is controlled by adjusting the initial time delay of both pump and Stokes pulses.

关键词：光波导拉曼放大率绝缘体硅斯托克斯脉冲

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Experimental study on the buckling of composite cylinders with reinforced circular hole under hydrostatic pressure

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Defence Technology(防务技术) 2025年第2期44卷 231-247页

作者： Zhun Li Xinhu zhang Kechun Shen Jing Liu Jian zhang guang Pan School of Marine Science and Technology Northwestern Polytechnical UniversityXi'an 710072China Northwest Institute of Mechanical and Electrical Engineering Xianyang 712099China Jiangsu University of Science and Technology Zhenjiang 212003China

In this paper,a type of reinforcing structure for composite shell with single and through hole is *** experimental tests for the composite shells without hole,with single hole and reinforced structure,with through hole and reinforced structure subjected to hydrostatic pressure were carried out by the designed experimental test *** mechanical responses of the composite shells under hydrostatic pressure are obtained by the high-speed camera and strain *** results show that the entire deformation process of the shell can be divided into three:uniform compression,"buckling mode formation"and ***"buckling mode formation"process is captured and reported for the first *** the composite shell with single hole,the proposed reinforcing structure has a significant reinforcement effect on the shell and the buckling capacity of the shell is not weaker than the complete composite *** the composite shell with through hole,sealing effect can be achieved by the proposed reinforcing structure,but the buckling capacity of the shell after reinforcement can only reach 77%of the original buckling capacity.

关键词： Composite cylindrical shell Circular hole Reinforcing structure Buckling Hydrostatic pressure

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