scholarly journals Peak Parking-Moment Analysis Method for the Measurement of Surface Diffusion Coefficients

2009 ◽  
Vol 25 (2) ◽  
pp. 211-218 ◽  
Author(s):  
Kanji MIYABE ◽  
Yuko MATSUMOTO ◽  
Nobuho ANDO
Media Wisata ◽  
2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Sri Larasati

Teacher Quality is one factor that determines student achievement, the research to find out the relationship and contribution to the quality of teachers to student achievement in subjects Housekeeping. This Reseach is expected to expective to be useful for teachers to improve performance. To measure student achievement are used Pearson Product Moment analysis method. Of test data analysis can be seen that there is asignificant relationship with the teacher quality anatara student achiement, which toount (7.09423) is greater than ttable (2.021). Whereas the contribution of teacher quality on student achiement is the amount of KP 46.64% while the remaining 53.36% is determinedby other variables is one of the largest employment practices in the industry.


SPE Journal ◽  
2021 ◽  
pp. 1-26
Author(s):  
Zizhong Liu ◽  
Hamid Emami-Meybodi

Summary The complex pore structure and storage mechanism of organic-rich ultratight reservoirs make the hydrocarbon transport within these reservoirs complicated and significantly different from conventional oil and gas reservoirs. A substantial fraction of pore volume in the ultratight matrix consists of nanopores in which the notion of viscous flow may become irrelevant. Instead, multiple transport and storage mechanisms should be considered to model fluid transport within the shale matrix, including molecular diffusion, Knudsen diffusion, surface diffusion, and sorption. This paper presents a diffusion-based semianalytical model for a single-component gas transport within an infinite-actingorganic-rich ultratight matrix. The model treats free and sorbed gas as two phases coexisting in nanopores. The overall mass conservation equation for both phases is transformed into one governing equation solely on the basis of the concentration (density) of the free phase. As a result, the partial differential equation (PDE) governing the overall mass transport carries two newly defined nonlinear terms; namely, effective diffusion coefficient, De, and capacity factor, Φ. The De term accounts for the molecular, Knudsen, and surface diffusion coefficients, and the Φ term considers the mass exchange between free and sorbed phases under sorption equilibrium condition. Furthermore, the ratio of De/Φ is recognized as an apparent diffusion coefficient Da, which is a function of free phase concentration. The nonlinear PDE is solved by applying a piecewise-constant-coefficient technique that divides the domain under consideration into an arbitrary number of subdomains. Each subdomain is assigned with a constant Da. The diffusion-based model is validated against numerical simulation. The model is then used to investigate the impact of surface and Knudsen diffusion coefficients, porosity, and adsorption capacity on gas transport within the ultratight formation. Further, the model is used to study gas transport and production from the Barnett, Marcellus, and New Albany shales. The results show that surface diffusion significantly contributes to gas production in shales with large values of surface diffusion coefficient and adsorption capacity and small values of Knudsen diffusion coefficient and total porosity. Thus, neglecting surface diffusion in organic-rich shales may result in the underestimation of gas production.


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