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Pore pressure built-up in hydrate-bearing sediments during phase transition: A poromechanical approach

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Petroleum Science 2023年第1期20卷 482-494页

作者： Shui-Tao Zhang Lin-Lin Wang State Key Laboratory of Petroleum Resources and Prospecting China University of Petroleum(Beijing)Beijing102249China Department of Offshore Oil and Gas Engineering College of Safety and Ocean EngineeringChina University of Petroleum(Beijing)Beijing102249China

Due to the density contrast between the hydrate and methane gas,the pore pressure is accumulated in the sediment during the decomposition process of methane *** accumulation of pore pressure decreases the magnitude of effective stress,further triggering potential geological disasters such as *** paper establishes a theoretical framework to investigate the evolution of fluid pressure in the hydrate-bearing sediments during the decomposition *** model consists of two parts:an unsaturated thermo-poromechanical constitutive law as well as a phase equilibrium *** with the existing studies,the present work incorporates the effect of pore volume change into the pressure built-up *** addition,the capillary effect is considered,which plays a nontrivial role in fine-grained *** on this model,the evolution of fluid pressure is investigated in undrained *** is shown that four mechanisms mainly contribute to the pressure built-up:the density contrast between decomposing hydrate and producing fluid,the variation of pore volume,the compaction of hydrate due to variation of capillary pressure,and the thermal deformation of pore constituents induced by temperature *** these mechanisms,the density contrast dominates the pore pressure *** the combined effect of these contributions,the evolution of fluid pressure exhibits a strong nonlinearity during the decomposition process and can reach up to dozens of mega ***,this high-level pressure built-up results in a significant tensile strain,yielding potential fracturing of the sediment.

关键词： Methane hydrate Excess fluid pressure Poromechanical phase equilibrium

Methane hydrate formation in porous media:Overview and perspectives

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Journal of Energy Chemistry 2022年第11期31卷 454-480,I0012页

作者： Yue Qin Liyan Shang Zhenbo Lv Jianyu He Xu Yang Zhien Zhang College of Petroleum Engineering Liaoning Petrochemical UniversityFushun 113001LiaoningChina School of Environmental&Safety Engineering Liaoning Petrochemical UniversityFushun 113001LiaoningChina College of Petroleum and Chemical Engineering Liaoning Petrochemical UniversityFushun 113001LiaoningChina School of Computer Science Shenyang Aerospace UniversityShenyang 110135LiaoningChina Department of Chemical and Biomedical Engineering West Virginia UniversityMorgantownWV 26506United States

Natural gas hydrate(NGH)has recently received more attention as a cleaner alternative energy source that not only reduces carbon emissions caused by the use of conventional fossil fuels but also plays a key role in global climate ***,hydrate-based technologies,particularly hydrate-based carbon capture and storage,have enormous promise for decreasing global carbon emissions,and porous media play an important role in all hydrate-based ***,this paper reviews the recent applications of porous media in the field of methane hydrate(MH)formation and analyzes the influence of porous media systems on MH phase equilibria and formation *** is because the efficiency of hydrate-based technologies is determined mainly by the phase equilibrium and formation kinetics of *** influence of the nature of the media on MH formation in porous media systems is comprehensively summarized to understand how porous media can efficiently enhance the kinetics of hydrate *** are necessary for rapid hydrate formation,and the effect of various promoters on MH formation was also *** on the aforementioned overview and understanding,the mechanisms for MH formation in various porous media systems are ***,the future perspectives and challenges of hydrate-based technologies in tackling global climate change were *** review provides a fundamental understanding of the application and development of porous media in rapid hydrate formation,a fair evaluation of the performance of various porous media systems,and critical insights into major research foci.

关键词： Methane hydrate Porous media phase equilibrium Kinetics Carbon neutrality

A review of GEMC method and its improved algorithms

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Acta Geochimica 2023年第3期42卷 409-434页

作者： Liwen Zhang Yuhong Yang Kun Yin Yun Liu International Research Center for Planetary Science Chengdu University of TechnologyChengdu 610059China State Key Laboratory of Ore Deposit Geochemistry Institute of GeochemistryChinese Academy of SciencesGuiyang 550081China CAS Center for Excellence in Comparative Planetology Hefei 230026China

Gibbs Ensemble Monte Carlo(GEMC)is a molecular simulation method commonly used for simulating phase *** method has been proposed since 1987 and applied in many fields,such as geology,planetary science,chemical engineering,material science,*** method combines canonical(NVT),isobaricisothermal(NPT),and grand canonical(μVT)Monte Carlo techniques in a single *** GEMC method was developed on the fundamental law of phase equilibrium that chemical potentials of each phase all *** key factors affect the rationality and reliability of GEMC simulations:*** can be efficiently moved in/out from certain phase during simulation;*** can represent the whole system well,in other words,samplings hold good *** addition,various parallel methods have been developed to improve the simulation *** this review,an introduction to the theoretical fundamentals,improvements on particle movement and sampling protocols,acceleration techniques and some applications of the GEMC method will be *** is the first integrated review introducing the fundamentals,improvements and applications of the GEMC simulation method.

关键词： Gibbs Ensemble Monte Carlo Molecular simulation phase equilibrium

Calculation and application of liquidus projection

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Rare Metals 2006年第5期25卷 532-537页

作者： CHEN Shuanglin CAO Weisheng YANG Ying ZHANG Fan WU Kaisheng DU Yong YAustin Chang CompuTherm LLC 437 S. Yellowstone Dr. Suite 217 Madison W153719 USA Department of Materials Science and Engineering University of Wisconsin-Madison W153706 USA Powder Metallurgy Research Institute Central South University Changsha 410083 China

Liquidus projection usually refers to a two-dimensional projection of ternary liquidus univariant lines at constant pressure. The algorithms used in Pandat for the calculation of liquidus projection with isothermal lines and invariant reaction equations in a ternary system are presented. These algorithms have been extended to multicomponent liquidus projections and have also been implemented in Pandat. Some examples on ternary and quaternary liquidus projections are presented.

关键词： liquidus projection phase diagram phase equilibrium multicomponent system

Experimental study of phase equilibria on Co-Fe-rich side of Co-Al-Fe system

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Journal of Iron and Steel Research(International) 2020年第6期27卷 673-680页

作者： Jing-jing Wang Wei-sen Zheng Xiao-gang Lu Yan-lin He Qing-rong Yao Jiang Wang School of Materials Science and Engineering Shanghai UniversityShanghai 200444China Materials Genome Institute Shanghai UniversityShanghai200444China State Key Laboratory of Advanced Special Steel Shanghai UniversityShanghai200444China School of Materials Science and Engineering Guilin University of Electronic TechnologyGuilin 541004GuangxiChina

Despite various studies on Co-Al-Fe ternary system, its phase equilibria are still in doubt. phase equilibria, magnetic transition and bcc_A2/bcc_B2 order-disorder transformation at the Co-Fe-rich side of the Co-Al-Fe alloys were carefully investigated by means of electron probe microanalysis (EPMA), X-ray diffraction (XRD) and differential scanning calo-rimetry. The equilibrium phases and their compositions were determined by 18 alloy samples annealed at 900, 1000, 1100 and 1200℃ for 528, 336, 168 and 96h, respectively, followed by quenching. However, by adopting the above traditional method, bcc_A2 and fcc_A1 phases are difficult to be distinguished through XRD analysis at room temperature due to the martensitic transformation of fcc_A1 phase during quenching. For this reason, high-temperature insitu XRD technique was utilized to correctly establish the phase relationships among bcc_A2, bcc_B2 and fcc_A1 phases. The phase transformation between bcc_A2 and B2 phases was determined to be second order instead of first order at temperatures higher than 900℃. The equilibrium phases and compositions were further confirmed by fabricating 16 diffusion couples together with EPMA. Meanwhile, using three-dimensional differential scanning calorimetry method, bcc_A2/B2 and ferro-/paramagnetic transi-tions were determined with high accuracy.

关键词： Co-Al-Fe system phase equilibrium Martensitic transformation Order-disorder transition

A thermodynamic description of the Si-rich Si-Fe system

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Acta Metallurgica Sinica(English Letters) 2012年第4期25卷 249-255页

作者： Kai TANG Merete Tangstad SINTEF Materials and Chemistry N-7465 Trondheim Norway Department of Materials and Technology Norwegian University of Science and Technology TrondheimNorway

phase equilibria in the Si-rich domain of the Si-Fe system have been reassessed based on the recent DTA experimental results. Thermodynamic properties of liquid phase have been reassessed using the associated solution model. The properties of DIA- MOND_A4 mixture phase have been added in order to evaluate the phase equilibria for the pure silicon materials. The assessed system is able to reproduce the experi- mental values in the whole composition range of the Si-Fe system.

关键词： Si-Fe Thermodynamic Assessment phase equilibrium DTA

phase equilibria of low-Ni side in Nb-Ni-Ti system at 1100℃

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Rare Metals 2020年第8期39卷 936-941页

作者： Hong-Xiao Li Zhi-Chao Li Yu-Ping Ren Min Jiang Gao-Wu Qin Key Laboratory for Anisotropy and Texture of Materials Ministry of EducationNortheastern UniversityShenyang 110819China

The phase equilibria related to liquid phase in low-Ni side of Nb-Ni-Ti system at 1100℃were investigated through scanning electron microscope(SEM),electron probe micro-analyzer(EPMA),X-ray diffraction(XRD)and differential scanning calorimetry(DSC).The results show that there exists liquid phase in equilibrium with continuous solid solution(Nb,βTi)and compound TiNi in low-Ni side of Nb-Ni-Ti system at 1100℃.The liquid phase region originates from low-Ni side of binary TiNi system and extends to 9.4 at%Nb in isothermal section of Nb-Ni-Ti phase *** solid solubility of Nb in binary compound TiNi is about 10.6 at%.At 1100℃,there exist two three-phase regions consisting of liquid+(Nb,βTi)+TiNi and(Nb,βTi)+TiNi+X_B in Nb-Ni-Ti system,where X_B is the compound with hexagonal structure and composition of 32.8 Nb-44.5 Ni-22.7 *** wide two-phase region(Nb,βTi)+TiNi exists between these two three-phase *** this two-phase region,Ti content in continuous solid solution(Nb,βTi)varies from6.6 at%to 25.7 at%,but Ni content is almost the same,which is about 4.0 at%.The eutectic transformation L■(Nb,βTi)+TiNi takes place at about 1138℃in Nb-Ni-Ti ternary system.

关键词： Nb-Ni-Ti system phase equilibrium Liquid phase Solid solubility

Thermodynamic investigation of phase equilibria in Al–Si–V system

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Journal of Materials Science & Technology 2018年第9期34卷 1592-1601页

作者： Qun Luo Kang Li Qian Li State Key Laboratory of Advanced Special Steel & Shanghai Key Laboratory of Advanced Ferrometallurgy & School of Materials Science and Engineering Shanghai UniversityShanghai 200072 China Materials Genome Institute Shanghai UniversityShanghai 200444 China Shanghai Institute of Materials Genome Shanghai 200444 China

The Al-Si-V system is assessed to understand the phase equilibria of V-containing（3 d transition metal）Al-Si alloys, which are generally of great importance for technical applications. Four annealed alloys were prepared to study the phase equilibria of Al-rich corner（V ≤ 23.3 at.%, Si ≤ 57.6 at.%） in the temperature range of 500-930 ℃. The microstructure and phase constituents of the samples were determined by X-ray diffraction（XRD） and scanning electron microscopy（SEM） equipped with energy dispersive X-ray spectrometer（EDS）, The existence of ternary phase τ（Al（0.6） Si（1.4） V, TiSi2-type） was confirmed with the composition ranging from 17.98 to 18.59 at.% Al and 48.89-49.20 at.% Si. However, it did not equilibrate with fcc（Al） below 868℃, which was determined by differential scanning calorimetry（DSC）. The Si3 V5 appeared in Al58 5 Si（18.3） V（23.2） and Al64 7 Si（20.2） V（15.1） alloys annealed at 500 ℃. It nearly disappeared after3000 h-annealing and its thermodynamic stability was discussed. According to the measured phase relationships, the thermodynamic description of Al-Si-V system was optimized combing with the enthalpies of formation of binary and ternary compounds obtained by density functional theory（DFT）. The Si-V system was modified to obtain the congruent liquidus of Si3 V5 and enthalpy of formation of Si3 V5 and Si2 V with experimental data. By comparing the calculated phase equilibria and phase transitions with experimental data, it showed that a good agreement was reached. The description of Al-Si-V system could be used to guide the development of Al-Si alloys.

关键词： phase equilibrium Al-Si alloy CALPHAD method Intermetallic compounds Enthalpy of formation

Effect of SDS/THF on thermodynamic and kinetic properties of formation of hydrate from a mixture of gases(CH_4+C_2H_6+C_3H_8) for storing gas as hydrate

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Journal of Energy Chemistry 2016年第3期25卷 409-417页

作者： Himangshu Kakati Ajay Mandal Sukumar Laik Gas Hydrate Laboratory Department of Petroleum Engineering Indian School of Mines

In this work, the effect of sodium dodecyl sulfate(SDS) and combined effect of sodium dodecyl sulfate(SDS) and tetrahydrofuran(THF) on thermodynamic and kinetic properties of CH4+C2H6+C3H8hydrate formation have been studied. Four different concentrations of sodium dodecyl sulfate(100 ppm, 500 ppm,1000 ppm and 1500 ppm) have been used to see its effect on phase equilibrium condition and formation kinetics. Though sodium dodecyl sulfate(SDS) does not vary the pressure–temperature condition of hydrate formation, it has a prominent favorable effect on induction time, gas consumption, storage capacity and formation rate. The addition of 3%(mol) tetrahydrofuran(THF) to water + SDS system results in large shifts in phase equilibrium boundary to lower pressure and higher temperature. It has been noticed that the addition of tetrahydrofuran further enhances the formation rate. So the mixture of sodium dodecyl sulfate(SDS) and tetrahydrofuran(THF) can be effectively used as promoter for storing natural gas as hydrate.

关键词： phase equilibrium Induction time Formation rate Storage capacity