Field evidence indicates that proppant distribution and threshold pressure gradient have great impacts on well productivity.Aiming at the development of unconventional oil reservoirs in Triassic Chang-7 Unit,Ordos Bas...Field evidence indicates that proppant distribution and threshold pressure gradient have great impacts on well productivity.Aiming at the development of unconventional oil reservoirs in Triassic Chang-7 Unit,Ordos Basin of China,we presented an integrated workflow to investigate how(1)proppant placement in induced fracture and(2)non-linear flow in reservoir matrix would affect well productivity and fluid flow in the reservoir.Compared with our research before(Yue et al.,2020),here we extended this study into the development of multi-stage fractured horizontal wells(MFHWs)with large-scale complicated fracture geometry.The integrated workflow is based on the finite element method and consists of simulation models for proppant-laden fluid flow,fracture flow,and non-linear seepage flow,respectively.Simulation results indicate that the distribution of proppant inside the induced cracks significantly affects the productivity of the MFHW.When we assign an idealized proppant distribution instead of the real distribution,there will be an overestimation of 44.98%in daily oil rate and 30.63%in cumulative oil production after continuous development of 1000 days.Besides,threshold pressure gradient(TPG)also significantly affects the well performance in tight oil reservoirs.If we simply apply linear Darcy’s law to the reservoir matrix,the overall cumulative oil production can be overrated by 77%after 1000 days of development.In general,this research provides new insights into the development of tight oil reservoirs with TPG and meanwhile reveals the significance of proppant distribution and non-linear fluid flow in the production scenario design.展开更多
The competition between physical aging and structural rejuvenation determines the physical and mechanical properties of glassy materials.Thus,the rejuvenation-aging boundary must be identified quantitatively.In this w...The competition between physical aging and structural rejuvenation determines the physical and mechanical properties of glassy materials.Thus,the rejuvenation-aging boundary must be identified quantitatively.In this work,we unravel a stress boundary to distinguish rejuvenation from aging via the thermo-mechanical creep of a typical Zr-based metallic glass.The crept glasses were rejuvenated into high-enthalpy disordered states when the applied stress exceeded a threshold that was numerically close to the steady-state flow stress;otherwise,the glasses were aged.A theoretical model for glass creep was adopted to demystify the observed stress threshold of rejuvenation.The model revealed that the thermo-mechanical creep beyond the threshold stress could activate sufficient shear transformations to create a net free volume,thus leading to structural rejuvenation.Furthermore,we derived the analytical expressions for the threshold and flow stresses.Both stresses can act as the rejuvenation-aging boundary,which is well supported by experimental creep data.The present work procures a deeper understanding of the rejuvenation mechanism of glasses and provides useful implications for abstaining from glass aging.展开更多
In this study,we observe that there are two threshold speeds(stability threshold speed and second threshold speed)for the long journal bearing,which is different for the short bearing.When the rotating speed is below ...In this study,we observe that there are two threshold speeds(stability threshold speed and second threshold speed)for the long journal bearing,which is different for the short bearing.When the rotating speed is below the stability threshold speed,the stability boundary nearly coincides with the clearance circle,and the journal center gradually returns to the equilibrium point after being released at an initial point.If the rotating speed is between the stability threshold speed and the second threshold speed,after being released at an initial point,the journal center converges to a contour containing the equilibrium point.In this situation,for a higher rotating speed,the corresponding contour is also larger.When the rotating speed exceeds the second threshold speed,the journal gradually moves towards the bearing surface after being released at an initial point.展开更多
Drying is a technique that involves removal of moisture using heat energy. This heat affects the protein components in foods especially the thiosulphide groups, which causes hydrophobic bond break that has been attrib...Drying is a technique that involves removal of moisture using heat energy. This heat affects the protein components in foods especially the thiosulphide groups, which causes hydrophobic bond break that has been attributed greatly to denaturation during drying. Safe moisture content (SMC) is the extent to which moisture can be withdrawn from food crops during drying that such crops can be considered safe for storage with minimal loss of nutritional qualities. Several reported minimum moisture contents, and bulk nutrients’ levels of crops were collected for the purpose of this review, and scattered plot graph was employed to determine the levels of bond interaction between moisture content and each bulk nutrients in the various dried food categories. The moisture contents in grains, root and tuber crops, fruits and vegetables, and cash crops formed a SMC threshold boundary within the 6% - 14%;0% - 10%;0% - 22%;and 0% - 30% respectively. Crude fibre and most especially the ash content played the most crucial role by providing the strongest bond interaction with migrating moisture during drying of all the food crops’ categories, and are of utmost important in the determination of SMC.展开更多
The nonlinear flow of liquids through nanoscale channels play an important role in the separation and purification properties of porous membranes,the manufacture of biofilm ionic channels and microfluidic chips,the pr...The nonlinear flow of liquids through nanoscale channels play an important role in the separation and purification properties of porous membranes,the manufacture of biofilm ionic channels and microfluidic chips,the production of micro electro-mechanical systems.Silicon oil flow experiments were conducted through anodic alumina films with pore sizes of 26,67,89,and 124 nm,in which flow mechanism and characteristics of the oil through the nanoscale channels were analyzed.Four nanoflow features are revealed:(1)The experimental flow rate is less than the theoretical flow rate through nanochannels,as solid-liquid interaction increasing flow resistance.(2)At small shear rate,the boundary layer is one,indicating existence of a threshold pressure of oil flow through nanochannels.(3)The boundary layer decreases with the increasing of shear rate,and it rapidly decreases as shear rate increases when the value of shear rate is small.(4)The drag coefficient decreases nonlinearly with increasing shear rate,decreasing more slowly when value of shear rate is big,and trending towards 1 in the case of large shear rate.It is shown that the non-linearity of flow is induced by great solid-liquid interaction in nano and microscale,and increasing the driving force can raise the efficiency at the nanometer scale.展开更多
基金The authors gratefully acknowledge the financial supports from the National Science Foundation of China under Grant 52274027 as well as the High-end Foreign Experts Recruitment Plan of the Ministry of Science and Technology China under Grant G2022105027L.
文摘Field evidence indicates that proppant distribution and threshold pressure gradient have great impacts on well productivity.Aiming at the development of unconventional oil reservoirs in Triassic Chang-7 Unit,Ordos Basin of China,we presented an integrated workflow to investigate how(1)proppant placement in induced fracture and(2)non-linear flow in reservoir matrix would affect well productivity and fluid flow in the reservoir.Compared with our research before(Yue et al.,2020),here we extended this study into the development of multi-stage fractured horizontal wells(MFHWs)with large-scale complicated fracture geometry.The integrated workflow is based on the finite element method and consists of simulation models for proppant-laden fluid flow,fracture flow,and non-linear seepage flow,respectively.Simulation results indicate that the distribution of proppant inside the induced cracks significantly affects the productivity of the MFHW.When we assign an idealized proppant distribution instead of the real distribution,there will be an overestimation of 44.98%in daily oil rate and 30.63%in cumulative oil production after continuous development of 1000 days.Besides,threshold pressure gradient(TPG)also significantly affects the well performance in tight oil reservoirs.If we simply apply linear Darcy’s law to the reservoir matrix,the overall cumulative oil production can be overrated by 77%after 1000 days of development.In general,this research provides new insights into the development of tight oil reservoirs with TPG and meanwhile reveals the significance of proppant distribution and non-linear fluid flow in the production scenario design.
基金This work was supported by the National Outstanding Youth Science Fund Project(Grant No.12125206)the National Natural Science Foundation of China(Grant Nos.11972345,and 11790292)the NSFC Basic Science Center for“Multiscale Problems in Nonlinear Mechanics”(Grant No.11988102).
文摘The competition between physical aging and structural rejuvenation determines the physical and mechanical properties of glassy materials.Thus,the rejuvenation-aging boundary must be identified quantitatively.In this work,we unravel a stress boundary to distinguish rejuvenation from aging via the thermo-mechanical creep of a typical Zr-based metallic glass.The crept glasses were rejuvenated into high-enthalpy disordered states when the applied stress exceeded a threshold that was numerically close to the steady-state flow stress;otherwise,the glasses were aged.A theoretical model for glass creep was adopted to demystify the observed stress threshold of rejuvenation.The model revealed that the thermo-mechanical creep beyond the threshold stress could activate sufficient shear transformations to create a net free volume,thus leading to structural rejuvenation.Furthermore,we derived the analytical expressions for the threshold and flow stresses.Both stresses can act as the rejuvenation-aging boundary,which is well supported by experimental creep data.The present work procures a deeper understanding of the rejuvenation mechanism of glasses and provides useful implications for abstaining from glass aging.
基金This research is supported by doctoral research fund of Hubei University of Arts and Science(No.2059023)the Project of Hubei University of Arts and Science(No.XK2020005)+2 种基金National Science and Technology Major Project(No.2019ZX04001024)Central Government Guides Local Science and Technology Development Projects of Hubei Province(No.2018ZYYD016)start-up program for excellent young and middle-aged scientific and technological innovation team of Hubei Provincial Department of Education(No.T201919).
文摘In this study,we observe that there are two threshold speeds(stability threshold speed and second threshold speed)for the long journal bearing,which is different for the short bearing.When the rotating speed is below the stability threshold speed,the stability boundary nearly coincides with the clearance circle,and the journal center gradually returns to the equilibrium point after being released at an initial point.If the rotating speed is between the stability threshold speed and the second threshold speed,after being released at an initial point,the journal center converges to a contour containing the equilibrium point.In this situation,for a higher rotating speed,the corresponding contour is also larger.When the rotating speed exceeds the second threshold speed,the journal gradually moves towards the bearing surface after being released at an initial point.
文摘Drying is a technique that involves removal of moisture using heat energy. This heat affects the protein components in foods especially the thiosulphide groups, which causes hydrophobic bond break that has been attributed greatly to denaturation during drying. Safe moisture content (SMC) is the extent to which moisture can be withdrawn from food crops during drying that such crops can be considered safe for storage with minimal loss of nutritional qualities. Several reported minimum moisture contents, and bulk nutrients’ levels of crops were collected for the purpose of this review, and scattered plot graph was employed to determine the levels of bond interaction between moisture content and each bulk nutrients in the various dried food categories. The moisture contents in grains, root and tuber crops, fruits and vegetables, and cash crops formed a SMC threshold boundary within the 6% - 14%;0% - 10%;0% - 22%;and 0% - 30% respectively. Crude fibre and most especially the ash content played the most crucial role by providing the strongest bond interaction with migrating moisture during drying of all the food crops’ categories, and are of utmost important in the determination of SMC.
基金Projects supported by the National Major Project of China(Grant No.2017ZX05072005)the National Natural Science Foundation of China(Grant No.11472246).
文摘The nonlinear flow of liquids through nanoscale channels play an important role in the separation and purification properties of porous membranes,the manufacture of biofilm ionic channels and microfluidic chips,the production of micro electro-mechanical systems.Silicon oil flow experiments were conducted through anodic alumina films with pore sizes of 26,67,89,and 124 nm,in which flow mechanism and characteristics of the oil through the nanoscale channels were analyzed.Four nanoflow features are revealed:(1)The experimental flow rate is less than the theoretical flow rate through nanochannels,as solid-liquid interaction increasing flow resistance.(2)At small shear rate,the boundary layer is one,indicating existence of a threshold pressure of oil flow through nanochannels.(3)The boundary layer decreases with the increasing of shear rate,and it rapidly decreases as shear rate increases when the value of shear rate is small.(4)The drag coefficient decreases nonlinearly with increasing shear rate,decreasing more slowly when value of shear rate is big,and trending towards 1 in the case of large shear rate.It is shown that the non-linearity of flow is induced by great solid-liquid interaction in nano and microscale,and increasing the driving force can raise the efficiency at the nanometer scale.
