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Combined use of fly ash and silica to prevent the long-term strength retrogression of oil well cement set and cured at HPHT conditions

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Petroleum Science 2024年第2期21卷 1122-1134页

作者： Guo-Dong Cheng Xue-Yu Pang Jin-Sheng Sun Zheng-Song Qiu Chuang-Chuang Wang Jian-Kun Qin Ning Li School of Petroleum Engineering China University of Petroleum(East China)Qingdao266580ShandongChina National Key Laboratory of Deep Oil and Gas China University of Petroleum(East China)Qingdao266580ShandongChina Oil and Gas Engineering Research Institute(Tarim Oilfield Company) China National Petroleum CorporationTarim841000XinjiangChina

The long-term strength retrogression of silica-enriched oil well cement poses a significant threat to wellbore integrity in deep and ultra-deep wells, which is a major obstacle for deep petroleum and geothermal energy development. Previous attempts to address this problem has been unsatisfactory because they can only reduce the strength decline rate. This study presents a new solution to this problem by incorporating fly ash to the traditional silica-cement systems. The influences of fly ash and silica on the strength retrogression behavior of oil well cement systems directly set and cured under the condition of 200°C and 50 MPa are investigated. Test results indicate that the slurries containing only silica or fly ash experience severe strength retrogression from 2 to 30 d curing, while the slurries containing both fly ash and silica experience strength enhancement from 2 to 90 d. The strength test results are corroborated by further evidences from permeability tests as well as microstructure analysis of set cement. Composition of set cement evaluated by quantitative X-ray diffraction analyses with partial or no known crystal structure(PONKCS) method and thermogravimetry analyses revealed that the conversion of amorphous C-(A)-S-H to crystalline phases is the primary cause of long-term strength retrogression.The addition of fly ash can reduce the initial amount of C-(A)-S-H in the set cement, and its combined use with silica can prevent the crystallization of C-(A)-S-H, which is believed to be the working mechanism of this new admixture in improving long-term strength stability of oil well cement systems.

关键词： fly ash Long-term strength retrogression High temperature Quantitative X-ray diffraction(QXRD) Partial or no known crystal structure(PONKCS)

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Study on fly ash Based Porous Ceramsite as Biological Filter Media

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Agricultural Biotechnology 2024年第1期13卷 71-73页

作者： Ruigang WANG Shuo WANG Weijie LI Hailong LIU Shanxi Laboratory for Yellow River School of Environment and ResourcesShanxi UniversityTaiyuan 030006China

Using fly ash as a raw material,porous ceramic particles with an apparent density of 1.21 g/cm^(3),a visible porosity of 51.03%,and a specific surface area of 4.26 m^(2)/g were prepared and used as biofilter materials for wastewater treatment.Through SEM,XRD analysis,and heavy metal leaching analysis,it was found that porous ceramsite were porous materials with rough surfaces.After calcination,the newly formed mineral was silicate calcium feldspar.The heavy metal concentration in the leaching solution of porous ceramsite met the national surface water quality requirements.The treatment of domestic sewage showed that the volumetric loads of COD Cr,NH_(4)^(+)-N,and TN removed by the aerated biofilter were 5.23,0.98,and 0.35 kg/(m^(3)·d),respectively,with removal rates of 85.46%,96.13%,and 32.31%.

关键词： Porous ceramsite Domestic sewage fly ash

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Utilization of Basalt Saw Mud as a Spherical Porous Functional Aggregate for the Preparation of Ordinary Structure Concrete

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Journal of Wuhan University of Technology(Materials Science) 2024年第2期39卷 364-375页

作者：周永祥关青锋 LENG Faguang WANG Jing LI Tianjun Faculty of Architecture Civil and Transportation EngineeringBeijing University of TechnologyBeijing 100124China Key Laboratory of Urban Security and Disaster Engineering of Ministry of Education Beijing University of TechnologyBeijing 100012China School of Materials Science and Engineering Southeast UniversityNanjing 211189China Institute of Building Materials China Academy of Building ResearchBeijing 100013China State Key Laboratory of Building Safety and Built Environment Beijing 100013China Zhejiang Chinavigor E.P.Technology Co. Ltd.Zhejiang 315043China

To promote the production and application of artificial aggregates,save natural sand resources and protect the ecological environment,we evaluated the feasibility of using spherical porous functional aggregates(SPFAs) formed by basalt saw mud under autoclave curing in ordinary structural concrete.In our work,two types of prewetted functional aggregates were taken as replacements for natural aggregates with different volume substitution rates(0%,5%,10%,15%,20%,25%,and 30%) in the preparation of ordinary structural concrete with water-to-binder ratios(W/B) of 0.48 and 0.33.The effects of the functional aggregate properties and content,W/B,and curing age on the fluidity,density,mechanical properties and autogenous shrinkage of ordinary concrete were analyzed.The experimental results showed that the density of concrete declined at a rate of not more than 5%,and the 28 d compressive strength could reach 31.0-68.2 MPa.Low W/B,long curing age and high-quality functional aggregates were conducive to enhancing the mechanical properties of SPFAs concrete.Through the rolling effects,SPFAs can optimize the particle gradation of aggregate systems and improve the fluidity of concrete,and the water stored inside SPFAs provides an internal curing effect,which prolongs the cement hydration process and considerably reduces the autogenous shrinkage of concrete.SPFAs exhibits high strength and high density,as well as being more cost-effective and ecological,and is expected to be widely employed in ordinary structural concrete.

关键词： lightweight concrete civil concrete building basalt saw mud fly ash internal curing environmentally friendly

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Long-Term Performance and Microstructural Characterization of Dam Concrete in the Three Gorges Project

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Engineering 2024年第2期33卷 237-262页

作者： Chen Lyu Cheng Yu Chao Lu Li Pan Wenwei Li Jiaping Liu School of Materials Science and Engineering Southeast UniversityNanjing 211189China State Key Laboratory of High Performance Civil Engineering Materials Sobute New Materials Co.Ltd.Nanjing 211103China China Three Gorges Corporation Wuhan 430010China

This study investigates the long-term performance of laboratory dam concrete in different curing environments over ten years and the microstructure of 17-year-old laboratory concrete and actual concrete cores drilled from the Three Gorges Dam.The mechanical properties of the laboratory dam concrete,whether cured in natural or standard environments,continued to improve over time.Furthermore,the laboratory dam concrete exhibited good resistance to diffusion and a refined microstructure after 17 years.However,curing and long-term exposure to the local natural environment reduced the frost resistance.Microstructural analyses of the laboratory concrete samples demonstrated that moderate-heat cement and fine fly ash(FA)particles were almost fully hydrated to form compact micro structures consisting of large quantities of homogeneous calcium(alumino)silicate hydrate(C-(A)-S-H)gels and a few crystals.No obvious interfacial transition zones were observed in the microstructure owing to the longterm pozzolanic reaction.This dense and homogenous microstructure was the crucial reason for the excellent long-term performance of the dam concrete.A high FA volume also played a significant role in the microstructural densification and performance growth of dam concrete at a later age.The concrete drilled from the dam surface exhibited a loose microstructure with higher microporosity,indicating that concrete directly exposed to the actual service environment suffered degradation caused by water and wind attacks.In this study,both macro-performance and microstructural analyses revealed that the application of moderate-heat cement and FA resulted in a dense and homogenous microstructure,which ensured the excellent long-term performance of concrete from the Three Gorges Dam after 17 years.Long-term exposure to an actual service environment may lead to microstructural degradation of the concrete surface.Therefore,the retained long-term dam concrete samples need to be further researched to better understand its microstructural evolution

关键词： Three Gorges Dam Long-term performance Microstructural analysis Moderate-heat cement fly ash

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Tensile Strain Capacity Prediction of Engineered Cementitious Composites (ECC) Using Soft Computing Techniques

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Computer Modeling in Engineering & Sciences 2024年第3期138卷 2925-2954页

作者： Rabar H.Faraj Hemn Unis Ahmed Hardi Saadullah Fathullah Alan Saeed Abdulrahman Farid Abed Civil Engineering Department University of HalabjaHalabjaIraq University of Sulaimani College of EngineeringCivil Engineering DepartmentSulaimaniIraq Civil Engineering Department Komar University of Science and TechnologySulaimaniIraq Department of Engineering Kurdistan Institution for Strategic Studies and Scientific ResearchesSulaimaniIraq Department of Civil Engineering American University of SharjahSharjah26666UAE

Plain concrete is strong in compression but brittle in tension,having a low tensile strain capacity that can significantly degrade the long-term performance of concrete structures,even when steel reinforcing is present.In order to address these challenges,short polymer fibers are randomly dispersed in a cement-based matrix to forma highly ductile engineered cementitious composite(ECC).Thismaterial exhibits high ductility under tensile forces,with its tensile strain being several hundred times greater than conventional concrete.Since concrete is inherently weak in tension,the tensile strain capacity(TSC)has become one of the most extensively researched properties.As a result,developing a model to predict the TSC of the ECC and to optimize the mixture proportions becomes challenging.Meanwhile,the effort required for laboratory trial batches to determine the TSC is reduced.To achieve the research objectives,five distinct models,artificial neural network(ANN),nonlinear model(NLR),linear relationship model(LR),multi-logistic model(MLR),and M5P-tree model(M5P),are investigated and employed to predict the TSCof ECCmixtures containing fly ash.Data from115 mixtures are gathered and analyzed to develop a new model.The input variables include mixture proportions,fiber length and diameter,and the time required for curing the various mixtures.The model’s effectiveness is evaluated and verified based on statistical parameters such as R2,mean absolute error(MAE),scatter index(SI),root mean squared error(RMSE),and objective function(OBJ)value.Consequently,the ANN model outperforms the others in predicting the TSC of the ECC,with RMSE,MAE,OBJ,SI,and R2 values of 0.42%,0.3%,0.33%,0.135%,and 0.98,respectively.

关键词： Engineered cementitious composites fly ash curing time tensile strain capacity modeling

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Study of the reinforced mechanism of fly ash on amphiphilic polymer gel

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Petroleum Science 2022年第5期19卷 2175-2184页

作者： Bo-Bo Zhou Wan-Li Kang Hong-Bin Yang Zhe Li Li-Ping Ma Shi-Tou Wang Jia-Qi Wang An-Qing Xie Bauyrzhan Sarsenbekuly Key Laboratory of Unconventional Oil&Gas Development(China University of Petroleum(East China)) Ministry of EducationQingdao266580ShandongPR China School of Petroleum Engineering China University of Petroleum(East China)Qingdao266580ShandongPR China Oil and Gas Technology Research Institute Changqing Oilfield Branch CompanyPetroChinaXi'an710018ShaanxiPR China Kazakh-British Technical University Almaty050000Kazakhstan

Amphiphilic polymer gels are widely used in heterogeneous reservoirs for conformance control technology.However,in high temperature and high salinity of calcium and magnesium reservoirs,amphiphilic polymer gels cannot maintain effective performance.In this work,a novel reinforced amphiphilic polymer gel(F-PADC gel)was prepared by physically mixing polymer solution and fly ash(FA),which is an extremely low cost material.The viscoelasticity and stability of the F-PADC gel were studied by rheometry and micro-rheometry.The reinforced mechanism of FA on amphiphilic polymer gels was revealed.The results show that the addition of FA can make the gel more robust with a denser network structure.On the fifth day,the elastic modulus(G’)increases from 5.2 to 7.0 Pa and the viscosity modulus(G")increases from 0.4 to 0.6 Pa at the frequency of 1 Hz,which improves the viscoelasticity of the gel system.More importantly,the F-PADC gel does not degrade after aging at 85℃for 180 d.And its viscoelasticity increases obviously,G′and G"increase to 110.0 Pa and 3.5 Pa,respectively,showing excellent anti-aging stability.Moreover,FA amphiphilic polymer gels have a good injectivity and a perfect plugging rate of 98.86%,which is better than that of sole amphiphilic polymer gels.This novel mixed FA amphiphilic polymer gels can prove to be a better alternative to conventional polymer gels to enhance oil recovery in high temperature and high salinity reservoirs.

关键词： Reinforced amphiphilic polymer gel fly ash Anti-aging stability Conformance control

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Characterization and mode of occurrence of rare earth elements and yttrium in fly and bottom ash from coal-fired power plants in Java,Indonesia

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International Journal of Coal Science & Technology 2022年第2期9卷 229-244页

作者： Dea Anisa Ayu Besari Ferian Anggara Widya Rosita Himawan T.B.M.Petrus Department of Geological Engineering Graduate School of Geological EngineeringUnversitas Gadjah MadaJalan Grafika No.2 Kampus UGM BulaksumurD.I.Yogyakarta 55281Indonesia Department of Geological Engineering Faculty of EngineeringUniversitas Gadjah MadaJalan Grafika No.2 Kampus UGM BulaksumurD.I.Yogyakarta 55281Indonesia Unconventional Geo-Resources Research Group Faculty of EngineeringUniversitas Gadjah MadaJalan Grafika No.2 Kampus UGM BulaksumurD.I.Yogyakarta 55281Indonesia Department of Nuclear Engineering and Engineering Physics Faculty of EngineeringUniversitas Gadjah MadaJalan Grafika No.2 Kampus UGM BulaksumurD.I.Yogyakarta 55281Indonesia Department of Chemical Engineering Faculty of EngineeringUniversitas Gadjah MadaJalan Grafka No.2 Kampus UGM BulaksumurD.I.Yogyakarta 55281Indonesia

fly and bottom ash(FABA)produced primarily from coal combustion in a coal-fred power plant consists of fne particles of the organic and inorganic mixture and trace elements.Eight FABA samples from coal-fred power plants in Java,Indonesia,had been collected for composition and rare earth element and Yttrium(REY)mode of occurrence identifcation.The geochemical composition of both major and trace elements was determined by inductively coupled plasma-mass spectrometry/atomic emission spectrometry(ICP-MS/AES).Furthermore,the composition of FABA was identifed by petrography with refected light microscopy and X-ray difraction(XRD)analysis.Simultaneously,scanning electron microscope determines the mode of occurrence of REY with an energy-dispersive X-ray(SEM–EDX).The study fnds that the inorganic component of FABA consists of glass,Fe–Mg spinel,mullite,quartz,Fe-oxide mineral,and K-feldspar.In contrast,the organic component is dominated by unburned coal.Glass is the most abundant component with cenospheres as major and pleiospheres as minor constituents.Trace elements analysis indicates REY concentration with heavy REY(HREY)distribution pattern.Moreover,SEM–EDX analysis results show that Yttrium(Y)occurs in glass and has a low concentration in spinel.From the mode occurrence of REY,in particular Yttrium,it can be predicted that alkaline fusion followed by acid leaching will be the most appropriate extraction method to extract REY from Indonesian FABA.

关键词： REY fly ash Bottom ash Glass Indonesia

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Waste fly ash-ZnO as a novel sunlight-responsive photocatalyst for dye discoloration

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Water Science and Engineering 2023年第1期16卷 76-82页

作者： Leena V.Bora Sonal P.Thakkar Kevin S.Vadaliya Nisha V.Bora Nirma University AhmedabadGujarat 382481India Government Engineering College ModasaGujarat 383315India

Treating waste with a waste material using freely available solar energy is the most effective way towards sustainable future.In this study,a novel photocatalyst,partly derived from waste material from the coal industry,was developed.fly ash hybridized with ZnO(FAeZn)was synthesized as a potential photocatalyst for dye discoloration.The synthesized photocatalyst was characterized by X-ray diffraction,scanning electron microscopy,transmission electron microscopy,and ultravioletevisible/near infra-red spectroscopy.The photocatalytic activity was examined with the discoloration of methylene blue used as synthetic dye wastewater.All the experiments were performed in direct sunlight.The photocatalytic performance of FAeZn was found to be better than that of ZnO and the conventionally popular TiO2.The LangmuireHinshelwood model rate constant values of ZnO,TiO2,and FAeZn were found to be 0.016 min1,0.017 min1,and 0.020 min1,respectively.There were two reasons for this:(1)FAeZn was able to utilize both ultraviolet and visible parts of the solar spectrum,and(2)its BrunauereEmmetteTeller surface area and porosity were significantly enhanced.This led to increased photon absorption and dye adsorption,thus exhibiting an energy-efficient performance.Therefore,FAeZn,partly derived from waste,can serve as a suitable material for environmental remediation and practical solar energy applications.

关键词： Photocatalyst ZnO fly ash Geopolymer Wastewater treatment Methylene blue

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In situ synthesis of MIL-53-type eco-MOF from high-alumina fly ash for efficiently removing fluoride from water

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Progress in Natural Science:Materials International 2023年第5期33卷 681-690页

作者： Ning Yuan Kaiqi Tan Qiuyu Li Xinling Zhang Yixiang Bao State Key Laboratory of Water Resource Protection and Utilization in Coal Mining National Institute of Clean and Low Carbon Energy School of Chemical and Environmental Engineering China University of Mining and Technology

Facing ubiquitous fluoride pollution in aquatic environments and ever-increasing discharge of coal fly ashes,this study aims to in situ synthesize a kind of Al-based metal-organic framework eco-material(eco-MOF) using highalumina fly ash as metal raw material,and apply the obtained adsorbent to efficiently adsorb fluoride in water.The synthesized eco-MIL-53(Al) exhibits excellent thermal stability,showcasing a consistent morphology of fine columnar crystals and possessing a high specific surface area(353 m2·g-1).Moreover,the adsorption isotherm demonstrates a strong agreement with the Langmuir isotherm model,indicative of a maximum uptake quantity of160 mg·g-1at 318 K.In addition,fluoride adsorption experiments demonstrate that an increased dosage enhances the adsorption efficiency,the higher water pH value diminishes the removal efficiency,and the impact of coexisting anions is minimal.Also,the adsorption capacity is augmented with increasing temperature at high initial fluoride concentrations,but shows negligible variation at low initial fluoride concentrations.It is worth noting that the desiliconization filtrate can be applied to synthesize ZSM-5 zeolite,realizing the total utilization of fly ash.The present work provides a novel platform that would serve as a mutually beneficial reference for managing the environmental risks of fluoride and waste resource utilization.

关键词： Adsorption Defluoridation Fluoride fly ash Metal–organic frameworks

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Investigation on the effects of fluid intensification based preconditioning process on the decarburization enhancement of fly ash

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Chinese Journal of Chemical Engineering 2022年第4期35卷 275-283页

作者： Danlong Li Yannan Liang Hainan Wang Ruoqian Zhou Xiaokang Yan Lijun Wang Haijun Zhang National Engineering Research Center of Coal Preparation and Purification China University of Mining and TechnologyXuzhou 221116China School of Chemical Engineering and Technology China University of Mining and TechnologyXuzhou 221116China School of Electrical and Engineering China University of Mining and TechnologyXuzhou 221116China

fly ash(FA)is a complex and abundant solid waste created by humans,and has caused environmental issues,for which flotation is an effective technique employed before its comprehensive utilization.However,the complex and hydrophilic characteristics of FA particles cannot naturally fulfill the selective separation by common flotation.Therefore,this study aims to provide an insight into fluid intensification effects on flotation to achieve the enhancement of FA surface property and decarburization.The relevant effects and mechanisms are investigated,based on the measurements of zeta potential,infrared spectroscopy,contact/wrap angle,induction time,size distribution and scanning electron microscopy–energy dispersive spectrometry.Experimental results manifested that the maximum unburned carbon recovery(73.25%)and flotation rate(0.2037 s^(-1)) were achieved with preconditioning energy inputs of 14.23 and6.57 W·kg^(-1) respectively.With increasing preconditioning energy inputs,fluid intensification effects could promote the inter-particle collision/attrition,detachment of hydrophilic existence and collector adsorption on particles.Correspondingly,absorbance of some hydrophobic and hydrophilic functional groups was strengthened and weakened respectively,which accounted for the improved interfacial properties,reflected as the increased contact and wrap angles,together with declined induction time.Overall,this article revealed the positive influences of fluid intensification based preconditioning process on rendering particle surface hydrophobic and improving separation performance.

关键词： fly ash Waste treatment Preconditioning energy input Fluid intensification Flotation Kinetic modeling

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