The shear strength of gas-hydrate-bearing reservoirs is one of the most important parameters used to study mechanical properties of gas-hydrate-bearing reservoirs. The shear strength of gas-hydrate- bearing reservoirs...The shear strength of gas-hydrate-bearing reservoirs is one of the most important parameters used to study mechanical properties of gas-hydrate-bearing reservoirs. The shear strength of gas-hydrate- bearing reservoirs changes with filling and cementation of gas hydrates, which will affect the wellbore and reservoir stability. Traditional shear tests could not be conducted on gas-hydrate-bearing core samples because the gas hydrates exist under a limited range of temperature and pressure conditions. This paper describes a novel shear apparatus for studying shear strength of gas-hydrate-bearing core samples under original reservoir conditions. The preparation of gas-hydrate-bearing core samples and subsequent shear tests are done in the same cell. Cohesion and internal friction angle of the core samples with different saturations of gas hydrates were measured with the apparatus. The effect of gas hydrates on the shear strength of reservoirs was quantitatively analyzed. This provides a foundation for studying wellbore and reservoir stability of gas-hydrate-bearing reservoirs.展开更多
The simultaneous influence of thermal and mechanical treatment was applied to produce a geometrically complex shaft from 51CrV4 steel leading to the formation of mierostruetures which were significantly different from...The simultaneous influence of thermal and mechanical treatment was applied to produce a geometrically complex shaft from 51CrV4 steel leading to the formation of mierostruetures which were significantly different from each other. These mierostrue- rural differences were accompanied by a local change of mechanical properties in terms of hardness, electrical resistivity and especially internal friction. The Snoek-KSster peak was recognized and analyzed in the structure of this steel.展开更多
Inthis paper, theinvestigation of applying internalfriction ( ultrasonic attenuation) andmodulus defect(ultrasonic velocity change) tostudy the variation of dislocation density andlooplength withcycle numberintheearly...Inthis paper, theinvestigation of applying internalfriction ( ultrasonic attenuation) andmodulus defect(ultrasonic velocity change) tostudy the variation of dislocation density andlooplength withcycle numberintheearly fativipageisreviewed. On this basis,thecon ceptof characterization of fatigue microcrackformation and propagation assessed bythe mea surementofinternalfriction and dynamicalelastic modulusissuggested. Theanalyticalex pressionoftheinternalfriction and modulus defect associated with microcracksiscalculated underthe assumptionthatthe mechanicalenergy dissipation iscaused by the mutualfriction betweentheoppositefacesofthe microcrack.展开更多
heinternalfriction at400 850 ℃in a high pure Fe Nb Calloy hasbeen measured, and a largestress dependent magnetomechanicalhysteresisdamping peakof whichthe peaktempera turevariesfrom 666 to740℃asstrain amplitu...heinternalfriction at400 850 ℃in a high pure Fe Nb Calloy hasbeen measured, and a largestress dependent magnetomechanicalhysteresisdamping peakof whichthe peaktempera turevariesfrom 666 to740℃asstrain amplitudechanges wasdiscovered. Theconditionsof the peak appearing and disappearing,somecharactersofthepeakandtheeffectofsomefac torsuch asascending and descending temperature, frequency, amplitude, deformation andannealing etconthe peak havealso beenstudied. The method to determinetheinternalstress σstand σi obstructing Barkhausen jumps of domains by internal friction experiences and the physical mechanism producingthe magnetomechanicalhysteresisdamping temperature( Qm 1 T) peakinthealloy were proposed.展开更多
基金support from"Preliminary Research on natural gas hydrates production"from SINOPEC(No.P06070)
文摘The shear strength of gas-hydrate-bearing reservoirs is one of the most important parameters used to study mechanical properties of gas-hydrate-bearing reservoirs. The shear strength of gas-hydrate- bearing reservoirs changes with filling and cementation of gas hydrates, which will affect the wellbore and reservoir stability. Traditional shear tests could not be conducted on gas-hydrate-bearing core samples because the gas hydrates exist under a limited range of temperature and pressure conditions. This paper describes a novel shear apparatus for studying shear strength of gas-hydrate-bearing core samples under original reservoir conditions. The preparation of gas-hydrate-bearing core samples and subsequent shear tests are done in the same cell. Cohesion and internal friction angle of the core samples with different saturations of gas hydrates were measured with the apparatus. The effect of gas hydrates on the shear strength of reservoirs was quantitatively analyzed. This provides a foundation for studying wellbore and reservoir stability of gas-hydrate-bearing reservoirs.
文摘The simultaneous influence of thermal and mechanical treatment was applied to produce a geometrically complex shaft from 51CrV4 steel leading to the formation of mierostruetures which were significantly different from each other. These mierostrue- rural differences were accompanied by a local change of mechanical properties in terms of hardness, electrical resistivity and especially internal friction. The Snoek-KSster peak was recognized and analyzed in the structure of this steel.
文摘Inthis paper, theinvestigation of applying internalfriction ( ultrasonic attenuation) andmodulus defect(ultrasonic velocity change) tostudy the variation of dislocation density andlooplength withcycle numberintheearly fativipageisreviewed. On this basis,thecon ceptof characterization of fatigue microcrackformation and propagation assessed bythe mea surementofinternalfriction and dynamicalelastic modulusissuggested. Theanalyticalex pressionoftheinternalfriction and modulus defect associated with microcracksiscalculated underthe assumptionthatthe mechanicalenergy dissipation iscaused by the mutualfriction betweentheoppositefacesofthe microcrack.
文摘heinternalfriction at400 850 ℃in a high pure Fe Nb Calloy hasbeen measured, and a largestress dependent magnetomechanicalhysteresisdamping peakof whichthe peaktempera turevariesfrom 666 to740℃asstrain amplitudechanges wasdiscovered. Theconditionsof the peak appearing and disappearing,somecharactersofthepeakandtheeffectofsomefac torsuch asascending and descending temperature, frequency, amplitude, deformation andannealing etconthe peak havealso beenstudied. The method to determinetheinternalstress σstand σi obstructing Barkhausen jumps of domains by internal friction experiences and the physical mechanism producingthe magnetomechanicalhysteresisdamping temperature( Qm 1 T) peakinthealloy were proposed.
